Generic Environmental Impact 

Statement for License 

Renewal of Nuclear Plants

Supplement 48

Regarding South Texas 

Project, Units 1 and 2

Draft Report for Comment

Office of Nuclear Reactor Regulation

NUREG-1437

Supplement 48
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Generic Environmental Impact 

Statement for License Renewal 

of Nuclear Plants

Supplement 48

Regarding South Texas 

Project, Units 1 and 2

Draft Report for Comment

Manuscript Completed: November 2012

Date Published: November 2012

Office of Nuclear Reactor Regulation

NUREG-1437

Supplement 48
COMMENTS ON DRAFT REPORT

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iii

ABSTRACT

This supplemental environmental impact statement has been prepared in response to an 

application submitted by STP Nuclear Operating Company (STPNOC) to renew the operating 

licenses for South Texas Project (STP), Units 1 and 2, for an additional 20 years.

This supplemental environmental impact statement (SEIS) includes the preliminary analysis that 

evaluates the environmental impacts of the proposed action and alternatives to the proposed 

action. Alternatives considered include: new nuclear generation, natural gas-fired 

combined-cycle generation, supercritical coal-fired generation, combination alternative, 

purchased power, and not renewing the license (the no-action alternative).

The U.S. Nuclear Regulatory Commission’s (NRC’s) preliminary recommendation is that the 

adverse environmental impacts of license renewal for STP are not great enough to deny the 

option of license renewal for energy planning decisionmakers. This recommendation is based 

on the following:

• the analysis and findings in NUREG-1437, Volumes 1 and 2, Generic 

Environmental Impact Statement for License Renewal of Nuclear Plants; 

• the Environmental Report submitted by STPNOC; 

• consultation with Federal, state, local, and tribal government agencies; 

• the NRC’s environmental review; and

• consideration of public comments received during the scoping process. 

v 

TABLE OF CONTENTS

ABSTRACT................................................................................................................................iii

TABLE OF CONTENTS.............................................................................................................. v 

FIGURES.................................................................................................................................... x 

TABLES.....................................................................................................................................xi

EXECUTIVE SUMMARY .......................................................................................................... xv 

ABBREVIATIONS AND ACRONYMS ...................................................................................... xxi

1.0 PURPOSE AND NEED FOR ACTION .............................................................................. 1-1 

1.1 Proposed Federal Action........................................................................................... 1-1 

1.2 Purpose and Need for the Proposed Federal Action ................................................. 1-1 

1.3 Major Environmental Review Milestones................................................................... 1-1 

1.4 Generic Environmental Impact Statement................................................................. 1-3 

1.5 Supplemental Environmental Impact Statement........................................................ 1-5 

1.6 Cooperating Agencies............................................................................................... 1-5 

1.7 Consultations ............................................................................................................ 1-5 

1.8 Correspondence ....................................................................................................... 1-6 

1.9 Status of Compliance................................................................................................ 1-6 

1.10 References ............................................................................................................... 1-6 

2.0 AFFECTED ENVIRONMENT............................................................................................ 2-1 

2.1 Facility Description.................................................................................................... 2-1 

2.1.1 Reactor and Containment Systems ...................................................................... 2-1 

2.1.2 Radioactive Waste Management.......................................................................... 2-1 

2.1.3 Nonradiological Waste Management.................................................................... 2-4 

2.1.4 Plant Operation and Maintenance ........................................................................ 2-6 

2.1.5 Power Transmission System ................................................................................ 2-6 

2.1.6 Cooling and Auxiliary Water Systems................................................................... 2-7 

2.1.7 Facility Water Use and Quality ............................................................................. 2-9 

2.2 Surrounding Environment ....................................................................................... 2-12

2.2.1 Land Use............................................................................................................ 2-13

2.2.2 Air Quality and Meteorology ............................................................................... 2-13

2.2.3 Geologic Environment ........................................................................................ 2-15

2.2.4 Surface Water Resources .................................................................................. 2-17

2.2.5 Groundwater Resources..................................................................................... 2-19

2.2.6 Aquatic Resources ............................................................................................. 2-23

2.2.7 Terrestrial Resources ......................................................................................... 2-38

2.2.8 Protected Species and Habitats ......................................................................... 2-47

2.2.9 Socioeconomics ................................................................................................. 2-58

2.2.10 Historic and Archaeological Resources .............................................................. 2-70
Table of Contents

vi

2.3 Related Federal and State Activities ....................................................................... 2-72

2.4 References ............................................................................................................. 2-73

3.0 ENVIRONMENTAL IMPACTS OF REFURBISHMENT ..................................................... 3-1 

3.1 References ................................................................................................................... 3-3 

4.0 ENVIRONMENTAL IMPACTS OF OPERATION............................................................... 4-1 

4.1 Land Use .................................................................................................................. 4-1 

4.2 Air Quality ................................................................................................................. 4-1 

4.3 Surface Water Resources ......................................................................................... 4-2 

4.3.1 Generic Surface Water Issues.............................................................................. 4-2 

4.3.2 Surface Water Use Conflicts—Plants Using Makeup Water from a Small 

River with Low Flow ............................................................................................. 4-2 

4.4 Groundwater Resources ........................................................................................... 4-5 

4.4.1 Generic Groundwater Issues................................................................................ 4-5 

4.4.2 Groundwater Use Conflicts................................................................................... 4-6 

4.4.3 Groundwater Quality ............................................................................................ 4-9 

4.5 Aquatic Resources.................................................................................................. 4-11

4.5.1 Generic Aquatic Ecology Issues......................................................................... 4-11

4.5.2 Entrainment and Impingement............................................................................ 4-12

4.5.3 Thermal Shock ................................................................................................... 4-22

4.5.4 Mitigation............................................................................................................ 4-25

4.6 Terrestrial Resources.............................................................................................. 4-25

4.7 Protected Species and Habitats.............................................................................. 4-26

4.8 Human Health......................................................................................................... 4-33

4.8.1 Generic Human Health Issues............................................................................ 4-33

4.8.2 Radiological Impacts of Normal Operations........................................................ 4-33

4.8.3 Microbiological Organisms ................................................................................. 4-37

4.8.4 Electromagnetic Fields—Acute Effects............................................................... 4-38

4.8.5 Electromagnetic Fields—Chronic Effects............................................................ 4-39

4.9 Socioeconomics...................................................................................................... 4-40

4.9.1 Generic Socioeconomic Issues .......................................................................... 4-40

4.9.2 Housing.............................................................................................................. 4-40

4.9.3 Public Services—Public Utilities ......................................................................... 4-41

4.9.4 Public Services—Transportation ........................................................................ 4-41

4.9.5 Offsite Land Use ................................................................................................ 4-42

4.9.6 Historic and Archaeological Resources .............................................................. 4-43

4.9.7 Environmental Justice ........................................................................................ 4-45

4.10 Evaluation of New and Potentially Significant Information....................................... 4-51

4.11 Cumulative Impacts ................................................................................................ 4-52

4.11.1 Land Use............................................................................................................ 4-53

4.11.2 Air Quality .......................................................................................................... 4-53

4.11.3 Water Resources................................................................................................ 4-55
Table of Contents 

vii

4.11.4 Aquatic Resources ............................................................................................. 4-59

4.11.5 Terrestrial Resources ......................................................................................... 4-62

4.11.6 Human Health .................................................................................................... 4-64

4.11.7 Socioeconomics ................................................................................................. 4-66

4.11.8 Historic and Archaeological Resources .............................................................. 4-67

4.11.9 Summary of Cumulative Impacts........................................................................ 4-68

4.12 References......................................................................................................... 4-69

5.0 ENVIRONMENTAL IMPACTS OF POSTULATED ACCIDENTS....................................... 5-1 

5.1 Design Basis Accidents............................................................................................. 5-1 

5.2 Severe Accidents...................................................................................................... 5-2 

5.3 Severe Accident Mitigation Alternatives .................................................................... 5-3 

5.3.1 Overview of Severe Accident Mitigation Alternative Process ................................ 5-3 

5.3.2 Estimate of Risk ................................................................................................... 5-3 

5.3.3 Potential Plant Improvements............................................................................... 5-8 

5.3.4 Evaluation of Risk Reduction and Costs of Improvements.................................... 5-9 

5.3.5 Cost Benefit Comparison...................................................................................... 5-9 

5.3.6 Conclusions........................................................................................................ 5-11

5.4 References ............................................................................................................. 5-12

6.0 ENVIRONMENTAL IMPACTS OF THE URANIUM FUEL CYCLE, WASTE 

MANAGEMENT, AND GREENHOUSE GAS EMISSIONS .......................................... 6-1 

6.1 The Uranium Fuel Cycle ........................................................................................... 6-1 

6.2 Greenhouse Gas Emissions ..................................................................................... 6-3 

6.2.1 Existing Studies.................................................................................................... 6-3 

6.3 References ............................................................................................................... 6-9 

7.0 ENVIRONMENTAL IMPACTS OF DECOMMISSIONING ................................................. 7-1 

7.1 Decommissioning...................................................................................................... 7-1 

7.2 References ............................................................................................................... 7-2 

8.0 ENVIRONMENTAL IMPACTS OF ALTERNATIVES ......................................................... 8-1 

8.1 New Nuclear Generation........................................................................................... 8-4 

8.1.1 Air Quality ............................................................................................................ 8-5 

8.1.2 Surface Water Resources .................................................................................... 8-6 

8.1.3 Groundwater Resources....................................................................................... 8-7 

8.1.4 Aquatic Ecology ................................................................................................... 8-8 

8.1.5 Terrestrial Ecology ............................................................................................... 8-9 

8.1.6 Human Health ...................................................................................................... 8-9 

8.1.7 Land Use............................................................................................................ 8-10

8.1.8 Socioeconomics ................................................................................................. 8-10

8.1.9 Transportation.................................................................................................... 8-11

8.1.10 Aesthetics .......................................................................................................... 8-11

8.1.11 Historic and Archaeological Resources .............................................................. 8-12
Table of Contents

viii

8.1.12 Environmental Justice ........................................................................................ 8-13

8.1.13 Waste Management ........................................................................................... 8-14

8.1.14 Summary of Impacts of New Nuclear Generation............................................... 8-14

8.2 Natural Gas Fired Combined Cycle Generation ...................................................... 8-14

8.2.1 Air Quality .......................................................................................................... 8-16

8.2.2 Surface Water Resources .................................................................................. 8-18

8.2.3 Groundwater Resources..................................................................................... 8-19

8.2.4 Aquatic Ecology ................................................................................................. 8-19

8.2.5 Terrestrial Ecology ............................................................................................. 8-20

8.2.6 Human Health .................................................................................................... 8-21

8.2.7 Land Use............................................................................................................ 8-21

8.2.8 Socioeconomics ................................................................................................. 8-22

8.2.9 Transportation.................................................................................................... 8-22

8.2.10 Aesthetics .......................................................................................................... 8-23

8.2.11 Historic and Archaeological Resources .............................................................. 8-23

8.2.12 Environmental Justice ........................................................................................ 8-24

8.2.13 Waste Management ........................................................................................... 8-25

8.2.14 Summary of Impacts for the NGCC Generation Alternative ................................ 8-25

8.3 Supercritical Coal Fired Generation ........................................................................ 8-26

8.3.1 Air Quality .......................................................................................................... 8-28

8.3.2 Surface Water Resources .................................................................................. 8-31

8.3.3 Groundwater Resources..................................................................................... 8-31

8.3.4 Aquatic Ecology ................................................................................................. 8-32

8.3.5 Terrestrial Ecology ............................................................................................. 8-33

8.3.6 Human Health .................................................................................................... 8-33

8.3.7 Land Use............................................................................................................ 8-34

8.3.8 Socioeconomics ................................................................................................. 8-35

8.3.9 Transportation.................................................................................................... 8-35

8.3.10 Aesthetics .......................................................................................................... 8-36

8.3.11 Historic and Archaeological Resources .............................................................. 8-36

8.3.12 Environmental Justice ........................................................................................ 8-37

8.3.13 Waste Management ........................................................................................... 8-38

8.3.14 Summary of Impacts for the Supercritical Coal-Fired Generation Alternative...... 8-38

8.4 Combination Alternative.......................................................................................... 8-39

8.4.1 Air Quality .......................................................................................................... 8-40

8.4.2 Surface Water Resources .................................................................................. 8-43

8.4.3 Groundwater Resources..................................................................................... 8-44

8.4.4 Aquatic Ecology ................................................................................................. 8-44

8.4.5 Terrestrial Ecology ............................................................................................. 8-45

8.4.6 Human Health .................................................................................................... 8-46

8.4.7 Land Use............................................................................................................ 8-46
Table of Contents 

ix

8.4.8 Socioeconomics ................................................................................................. 8-47

8.4.9 Transportation.................................................................................................... 8-48

8.4.10 Aesthetics .......................................................................................................... 8-49

8.4.11 Historic and Archaeological Resources .............................................................. 8-49

8.4.12 Environmental Justice ........................................................................................ 8-50

8.4.13 Waste Management ........................................................................................... 8-51

8.4.14 Summary of Impacts of the Combination Alternative .......................................... 8-51

8.5 Purchased Power.................................................................................................... 8-52

8.5.1 Air Quality .......................................................................................................... 8-53

8.5.2 Surface Water and Groundwater Resources ...................................................... 8-53

8.5.3 Terrestrial and Aquatic Ecology.......................................................................... 8-53

8.5.4 Human Health .................................................................................................... 8-54

8.5.5 Land Use............................................................................................................ 8-54

8.5.6 Socioeconomics (including transportation and aesthetics).................................. 8-54

8.5.7 Historic and Archaeological Resources .............................................................. 8-54

8.5.8 Environmental Justice ........................................................................................ 8-54

8.5.9 Waste Management ........................................................................................... 8-55

8.5.10 Summary of Impacts of the Purchased Power Alternative................................... 8-55

8.6 Alternatives Considered but Dismissed................................................................... 8-55

8.6.1 Offsite Nuclear , Gas , and Coal Fired Capacity ................................................. 8-56

8.6.2 Energy Conservation and Energy Efficiency....................................................... 8-56

8.6.3 Wind Power........................................................................................................ 8-57

8.6.4 Solar Power........................................................................................................ 8-58

8.6.5 Hydroelectric Power ........................................................................................... 8-59

8.6.6 Wave and Ocean Energy ................................................................................... 8-59

8.6.7 Geothermal Power ............................................................................................. 8-59

8.6.8 Municipal Solid Waste ........................................................................................ 8-60

8.6.9 Biomass ............................................................................................................. 8-61

8.6.10 Biofuels .............................................................................................................. 8-61

8.6.11 Oil Fired Power .................................................................................................. 8-62

8.6.12 Fuel Cells ........................................................................................................... 8-62

8.6.13 Delayed Retirement............................................................................................ 8-62

8.7 No Action Alternative .............................................................................................. 8-63

8.7.1 Air Quality .......................................................................................................... 8-63

8.7.2 Surface Water Resources .................................................................................. 8-63

8.7.3 Groundwater Resources..................................................................................... 8-63

8.7.4 Aquatic Ecology ................................................................................................. 8-64

8.7.5 Terrestrial Ecology ............................................................................................. 8-64

8.7.6 Human Health .................................................................................................... 8-64

8.7.7 Land Use............................................................................................................ 8-64

8.7.8 Socioeconomics ................................................................................................. 8-64
Table of Contents

x 

8.7.9 Transportation.................................................................................................... 8-64

8.7.10 Aesthetics and Noise.......................................................................................... 8-65

8.7.11 Historic and Archaeological Resources .............................................................. 8-65

8.7.12 Environmental Justice ........................................................................................ 8-65

8.7.13 Waste Management ........................................................................................... 8-65

8.7.14 Summary of Impacts of No Action Alternative..................................................... 8-65

8.8 Alternatives Summary............................................................................................. 8-66

8.9 References ............................................................................................................. 8-68

9.0 CONCLUSION.................................................................................................................. 9-1 

9.1 Environmental Impacts of License Renewal.............................................................. 9-1 

9.2 Comparison of Alternatives ....................................................................................... 9-1 

9.3 Resource Commitments............................................................................................ 9-2 

9.3.1 Unavoidable Adverse Environmental Impacts ...................................................... 9-2 

9.3.2 Short Term Versus Long Term Productivity.......................................................... 9-2 

9.3.3 Irreversible and Irretrievable Commitments of Resources .................................... 9-3 

9.4 Recommendations.................................................................................................... 9-3 

10.0 LIST OF PREPARERS.................................................................................................. 10-1 

11.0 LIST OF AGENCIES, ORGANIZATIONS, AND PERSONS TO WHOM COPIES

OF THIS SUPPLEMENTAL ENVIRONMENTAL IMPACT STATEMENT ARE 

SENT......................................................................................................................... 11-1 

12.0 INDEX........................................................................................................................... 12-1 

APPENDIX A. COMMENTS RECEIVED ON THE STP ENVIRONMENTAL REVIEW ............ A-1 

APPENDIX B. NATIONAL ENVIRONMENTAL POLICY ACT ISSUES FOR LICENSE 

RENEWAL OF NUCLEAR POWER PLANTS.............................................................. B-1 

APPENDIX C. APPLICABLE REGULATIONS, LAWS, AND AGREEMENTS ......................... C-1 

APPENDIX D. CONSULTATION CORRESPONDENCE ........................................................ D-1 

APPENDIX E. CHRONOLOGY OF ENVIRONMENTAL REVIEW CORRESPONDENCE....... E-1 

APPENDIX F. NRC STAFF EVALUATION OF SEVERE ACCIDENT MITIGATION 

ALTERNATIVES ......................................................................................................... F-1 

Figures

Figure 1–1. Environmental Review Process............................................................................ 1-2 

Figure 1–2. Environmental Issues Evaluated For License Renewal ........................................ 1-4 

Figure 2–1. Surface Water Bodies and Groundwater Wells in Vicinity of STP 

(STPNOC 2011b)............................................................................................. 2-11

Figure 2–2. The STP Site and 1975 to 1976 Aquatic Ecology Sampling Location (NRC 

2011b).............................................................................................................. 2-27

Figure 2–3. The STP Site and 2007 to 2008 Aquatic Ecology Sampling Locations from 

Segment C through the Upstream Portion of Segment B (NRC 2011b)............ 2-28

Figure 2–4. The STP Site and 2007 to 2008 Aquatic Ecology Sampling Locations from 

the Downstream Portion of Segment B through Segment A (NRC 2011b) ....... 2-29
Table of Contents 

xi

Figure 2–5. Most Commonly Recorded Christmas Bird Count Species, 2007 through 

2011 (Audubon 2011)....................................................................................... 2-41

Figure 2–6. STP 50-mi (80-km) Radius Map (STPNOC 2010b) ............................................ 2-45

Figure 2–7. STP 6-mi (10-km) Radius Map (STPNOC 2010b) .............................................. 2-46

Figure 4–1. Species Richness of Aquatic Species Captured in Trawl Surveys from 

1974, 1983, and 2007 through 2008................................................................. 4-21

Figure 4–2. 2010 Census Minority Block Groups Within a 50 mi Radius of STP ................... 4-47

Figure 4–3. Census 2010 Low Income Block Groups Within a 50 mi Radius of STP............. 4-49

Tables

Table 2–1. Macroinvertebrates Collected in the Colorado River by Gear Type, 2007 to 

2008................................................................................................................. 2-31

Table 2–2. Fish Collected in the Colorado River by Gear Type, 2007 to 2008 ...................... 2-32

Table 2–3. Species Richness (number of species) in Three River Segments by Gear 

Type................................................................................................................. 2-33

Table 2–4. Fish and Invertebrates Collected in the MCR by Gill Nets, Seines, and 

Trawls, 2007 to 2008........................................................................................ 2-35

Table 2–5. Fish and Invertebrates Collected in the MCR by Plankton Tows, 2007 to 

2008................................................................................................................. 2-36

Table 2–6. Birds Observed in High Numbers for One Christmas Count Year, 2007 

through 2011.................................................................................................... 2-40

Table 2–7. Birds Documented on the STP Site, 2007 through 2008...................................... 2-42

Table 2–8. Species Listed Under the ESA ............................................................................ 2-47

Table 2–9. NMFS Species of Concern .................................................................................. 2-51

Table 2–10. Ecoregion 5 Species with Designated EFH ....................................................... 2-54

Table 2–11. State listed Species........................................................................................... 2-57

Table 2–12. STP, Employee Residence by County............................................................... 2-59

Table 2–13. Housing in Brazoria and Matagorda Counties in 2010....................................... 2-59

Table 2–14. Brazoria and Matagorda County City Public Water Supply Systems (in 

mgd)................................................................................................................. 2-60

Table 2–15. Major Commuting Routes in the Vicinity of STP, 2010 AADT ............................ 2-61

Table 2–16. Population and Percent Growth in Brazoria and Matagorda Counties from 

1970 to 2010 and Projected for 2020 to 2050................................................... 2-63

Table 2–17. Demographic Profile of the Population in the STP Two County 

Socioeconomic ROI in 2010............................................................................. 2-63

Table 2–18. Seasonal Housing in Counties Located within 50 mi of STP.............................. 2-64

Table 2–19. Migrant Farm Workers and Temporary Farm Labor in Counties Located 

within 50 mi of STP .......................................................................................... 2-65

Table 2–20. Major Industries in Matagorda County ............................................................... 2-66

Table 2–21. Major Industries in ROI...................................................................................... 2-66

Table 2–22. Estimated Income Information for STP ROI....................................................... 2-67

Table 2–23. Comparison of STP Owner Payments with Taxing District Property Tax ........... 2-68
Table of Contents

xii

Table 2–24. STP, Units 1 and 2, Owner Payments to Other Taxing Districts in 

Matagorda........................................................................................................ 2-70

Table 3–1. Category 1 Issues Related to Refurbishment ........................................................ 3-1 

Table 3–2. Category 2 Issues Related to Refurbishment ........................................................ 3-2 

Table 4–1. Land Use Issues.................................................................................................... 4-1 

Table 4–2. Air Quality Issues .................................................................................................. 4-2 

Table 4–3. Surface Water Resources Issues .......................................................................... 4-2 

Table 4–4. Surface Water Withdrawals and Usage for Calendar Years 2003–2010 for 

STP, Units 1 and 2 ............................................................................................. 4-4 

Table 4–5. Groundwater Resources Issues ............................................................................ 4-5 

Table 4–6. Projected Drawdown and Change in Drawdown in Feet for the Deep 

Chicot Aquifer for Selected Distances ................................................................ 4-7 

Table 4–7. Aquatic Resource Issues..................................................................................... 4-11

Table 4–8. Number (per 100 m3) of Macrozooplankton and Ichthyoplankton Collected 

in Plankton Samples in Front of the RMPF from 1984 and 1985 ...................... 4-14

Table 4–9. Invertebrates and Fish Impinged at the RMPF during 1983–1984 Studies .......... 4-15

Table 4–10. Aquatic Species Collected during Entrainment Sampling in the MCR’s 

CWIS for Units 1 and 2, 2007–2008 ................................................................. 4-16

Table 4–11. Aquatic Species Collected during Impingement Sampling in the MCR’s 

CWIS for Units 1 and 2, 2007–2008 ................................................................. 4-17

Table 4–12. Terrestrial Resources Issues Identified in the GEIS........................................... 4-26

Table 4–13. Protected Species Issues Identified in the GEIS................................................ 4-26

Table 4–14. Effect Determinations for Federally Listed Species............................................ 4-27

Table 4–15. Human Health Issues. Table B 1 of Appendix B to Subpart A of 10 CFR 

Part 51 contains more information on these issues. ......................................... 4-33

Table 4–16. Socioeconomics during the Renewal Term........................................................ 4-40

Table 4–17. Summary of Cumulative Impacts on Resource Areas........................................ 4-68

Table 5–1. Issues Related to Postulated Accidents Two issues related to postulated 

accidents are evaluated under the National Environmental Protection Act 

(NEPA) in the license renewal review—DBAs and severe accidents.................. 5-1 

Table 5–2. STP Core Damage Frequency for Internal Events................................................. 5-5 

Table 5–3. STP Core Damage Frequency for Fire Events ...................................................... 5-6 

Table 5–4. STP Core Damage Frequency for Seismic Events ................................................ 5-6 

Table 5–5. STP Core Damage Frequency for Other External Events...................................... 5-7 

Table 5–6. Breakdown of Population Dose by Containment Release Mode ............................ 5-8 

Table 5–7. Phase II SAMA List (Cost-Benefit) for STP.......................................................... 5-10

Table 6–1. Issues Related to the Uranium Fuel Cycle and Waste Management ..................... 6-1 

Table 6–2. Nuclear Greenhouse Gas Emissions Compared to Coal ....................................... 6-5 

Table 6–3. Nuclear Greenhouse Gas Emissions Compared to Natural Gas............................ 6-6 

Table 6–4. Nuclear Greenhouse Gas Emissions Compared to Renewable Energy 

Sources.............................................................................................................. 6-7 

Table 7–1. Table 7–1. Issues Related to Decommissioning .................................................... 7-1 
Table of Contents 

xiii

Table 8–1. Expected Annual Emissions from the Largest Stationary Sources of 

Emissions........................................................................................................... 8-6 

Table 8–2. Summary of Environmental Impacts of the New Nuclear Alternative 

Compared to Continued Operation of STP, Units 1 and 2 ................................ 8-14

Table 8–3. Summary of Environmental Impacts of the NGCC Alternative Compared to 

Continued Operation of STP ............................................................................ 8-25

Table 8–4. Summary of Environmental Impacts of the Supercritical Coal Fired 

Alternative Compared to Continued Operation of STP, Units 1 and 2............... 8-38

Table 8–5. Summary of Environmental Impacts of the Combination Alternative 

Compared to Continued Operation of STP, Units 1 and 2 ................................ 8-52

Table 8–6. Summary of Environmental Impacts of the Purchased Power Alternative 

Compared to Continued Operation of STP, Units 1 and 2 ................................ 8-55

Table 8–7. Summary of Environmental Impacts of the No Action Alternative Compared 

to Continued Operation of STP, Units 1 and 2.................................................. 8-65

Table 8–8. Summary of Environmental Impacts of Proposed Action and Alternatives ........... 8-67

Table 10–1. List of Preparers................................................................................................ 10-1 

Table A–1. Individuals Providing Comments During the Scoping Comment Period................. A-1 

Table B–1. Summary of Issues and Findings .......................................................................... B-1 

Table C–1. Licenses and Permits............................................................................................ C-1 

Table C–2. Federal, State, and Local Laws and Other Requirements ..................................... C-2 

Table D–1. Consultation Correspondence............................................................................... D-1 

Table E–1. Environmental Review Correspondence ............................................................... E-1 

Table F–1. STP Core Damage Frequency for Internal Events................................................. F-4 

Table F–2. STP Core Damage Frequency for Fire Events ...................................................... F-5 

Table F–3. STP Core Damage Frequency for Seismic Events ................................................ F-5 

Table F–4. STP Core Damage Frequency for Other External Events...................................... F-6 

Table F–5. Breakdown of Population Dose by Containment Release Mode............................ F-7 

Table F–6. STP PRA Historical Summary............................................................................... F-9 

Table F–7. SAMA Cost-Benefit Screening Analysis for STP ................................................. F-26

Table F–8. SAMA Cost-Benefit Screening Analysis for STP Using Conservative 

Source Terms................................................................................................... F-31

Table F–9. SAMA Cost-Benefit Screening Analysis for STP Using Updated Fire and 

Seismic Risk Analysis and Conservative Source Terms................................... F-32

xv 

EXECUTIVE SUMMARY

BACKGROUND

By letter dated October 25, 2010, STP Nuclear Operating Company (STPNOC) submitted an 

application to the U.S. Nuclear Regulatory Commission (NRC) to issue renewed operating 

licenses for South Texas Project (STP), Units 1 and 2, for an additional 20-year period.

Pursuant to Title 10, Part 51.20(b)(2) of the Code of Federal Regulations (10 CFR 51.20(b)(2)), 

the renewal of a power reactor operating license requires preparation of an environmental 

impact statement (EIS) or a supplement to an existing EIS. In addition, 10 CFR 51.95(c) states 

that the NRC shall prepare an EIS, which is a supplement to the Commission’s NUREG-1437, 

Generic Environmental Impact Statement (GEIS) for License Renewal of Nuclear Plants (GEIS). 

Upon acceptance of STPNOC’s application, the NRC staff began the environmental review 

process described in 10 CFR Part 51 by publishing a notice of intent to prepare a supplemental 

EIS (SEIS) and conduct scoping. In preparation of this SEIS for STP, the NRC staff performed 

the following:

• conducted public scoping meetings on March 2, 2011, in Bay City, Texas;

• conducted a site audit at the plant in July 2011; 

• reviewed STPNOC’s Environmental Report (ER) and compared it to the 

GEIS; 

• consulted with other agencies; 

• conducted a review of the issues following the guidance set forth in 

NUREG-1555, Standard Review Plans for Environmental Reviews for 

Nuclear Power Plants, Supplement 1: Operating License Renewal; and 

• considered public comments received during the scoping process. 

PROPOSED ACTION

STPNOC initiated the proposed Federal action—issuing renewed power reactor operating 

licenses—by submitting an application for license renewal of STP, for which the existing 

licenses (NPF-76 and NPF-80) for STP, Units 1 and 2, will expire on August 20, 2027, and 

December 15, 2028, respectively. The NRC’s Federal action is the decision whether or not to 

renew the licenses for an additional 20 years.

PURPOSE AND NEED FOR ACTION

The purpose and need for the proposed action (issuance of a renewed license) is to provide an 

option that allows for power generation capability beyond the term of the current nuclear power 

plant operating license to meet future system generating needs. Such needs may be 

determined by other energy-planning decisionmakers, such as State, utility, and—where 

authorized—Federal (other than NRC). This definition of purpose and need reflects the NRC’s 

recognition that, unless there are findings in the safety review required by the Atomic Energy 

Act or findings in the National Environmental Policy Act (NEPA) environmental analysis that 

would lead the NRC to reject a license renewal application, the NRC does not have a role in the 
Executive Summary

xvi

energy-planning decisions of whether a particular nuclear power plant should continue to 

operate.

If the renewed license is issued, the appropriate energy-planning decisionmakers, along with 

STPNOC, will ultimately decide if the reactor units will continue to operate based on factors 

such as the need for power. If the operating licenses are not renewed, then the facility must be 

shut down on or before the expiration dates of the current operating licenses—August 20, 2027, 

and December 15, 2028.

ENVIRONMENTAL IMPACTS OF LICENSE RENEWAL

The SEIS evaluates the potential environmental impacts of the proposed action. The 

environmental impacts from the proposed action are designated as SMALL, MODERATE, or 

LARGE. As set forth in the GEIS, Category 1 issues are those that meet all of the following 

criteria:

• The environmental impacts associated with the issue 

is determined to apply either to all plants or, for some 

issues, to plants having a specific type of cooling 

system or other specified plant or site characteristics.

• A single significance level (i.e., SMALL, MODERATE, 

or LARGE) has been assigned to the impacts, except 

for collective offsite radiological impacts from the fuel 

cycle and from high-level waste and spent fuel 

disposal.

• Mitigation of adverse impacts associated with the 

issue is considered in the analysis, and it has been 

determined that additional plant-specific mitigation 

measures are likely not to be sufficiently beneficial to 

warrant implementation.

For Category 1 issues, no additional site-specific analysis is required in this SEIS unless new 

and significant information is identified. Chapter 4 of this report presents the process for 

identifying new and significant information. Site-specific issues (Category 2) are those that do 

not meet one or more of the criterion for Category 1 issues; therefore, an additional site-specific 

review for these non-generic issues is required, and the results are documented in the SEIS. 

The NRC staff has reviewed STPNOC’s established process for identifying and evaluating the 

significance of any new and significant information on the environmental impacts of license 

renewal of STP. Neither STPNOC nor NRC identified information that is both new and 

significant related to Category 1 issues that would call into question the conclusions in the 

GEIS. This conclusion is supported by NRC’s review of the applicant’s ER, other 

documentation relevant to the applicant’s activities, the public scoping process and substantive 

comments raised, and the findings from the environmental site audit conducted by the NRC 

staff. Further, the NRC staff did not identify any new issues applicable to STP that have a 

significant environmental impact. The NRC staff, therefore, relies upon the conclusions of the 

GEIS for all Category 1 issues applicable to STP.

Table ES–1 summarizes the Category 2 issues applicable to STP, if any, as well as the NRC 

staff’s findings related to those issues. If the NRC staff determined that there were no 

Category 2 issues applicable for a particular resource area, the findings of the GEIS, as 

documented in Appendix B to Subpart A of 10 CFR Part 51, stand.

SMALL: Environmental 

effects are not detectable or 

are so minor that they will 

neither destabilize nor 

noticeably alter any important 

attribute of the resource.

MODERATE: Environmental 

effects are sufficient to alter 

noticeably, but not to 

destabilize, important 

attributes of the resource.

LARGE: Environmental 

effects are clearly noticeable 

and are sufficient to 

destabilize important attributes 

of the resource.
Executive Summary 

xvii

Table ES–1. NRC Conclusions Relating to Site-Specific Impacts of License Renewal

Resource Area Relevant Category 2 Issues Adverse Impacts

Land Use None SMALL

Air Quality None SMALL

Surface Water Resources Surface water use conflicts SMALL

Groundwater Resources Groundwater use conflicts SMALL

Aquatic Resources Entrainment & impingement of fish & shellfish SMALL

Heat shock SMALL

Terrestrial Resources None SMALL

Protected Species Threatened or endangered species SMALL

Human Health Issues Electromagnetic fields—acute effects (electric 

shock vs. chronic effects) 

SMALL to 

MODERATE

Microbiological organisms SMALL

Socioeconomics Housing Impacts

Public services (public utilities)

Offsite land use

Public services (public transportation)

Historic & archaeological resources

SMALL

SMALL

SMALL

SMALL

SMALL

With respect to environmental justice, the NRC staff has determined that there would be no 

disproportionately high and adverse impacts to these populations from the continued operation 

of STP during the license renewal period. Additionally, the NRC staff has determined that no 

disproportionately high and adverse human health impacts would be expected in special 

pathway receptor populations in the region as a result of subsistence consumption of water, 

local food, fish, and wildlife. 

SEVERE ACCIDENT MITIGATION ALTERNATIVES

Since STPNOC had not previously considered alternatives to reduce the likelihood or potential 

consequences of a variety of highly uncommon, but potentially serious, accidents at STP, 

10 CFR 51.53(c)(3)(ii)(L) requires that STPNOC evaluate severe accident mitigation alternatives 

(SAMAs) in the course of the license renewal review. SAMAs are potential ways to reduce the 

risk or potential impacts of uncommon, but potentially severe accidents, and they may include 

changes to plant components, systems, procedures, and training.

The NRC staff reviewed the ER’s evaluation of potential SAMAs. Based on the staff’s review, 

the NRC staff concluded that none of the potentially cost beneficial SAMAs relate to adequately 

managing the effects of aging during the period of extended operation. Therefore, they need 

not be implemented as part of the license renewal, pursuant to 10 CFR Part 54.

ALTERNATIVES

The NRC staff considered the environmental impacts associated with alternatives to license 

renewal. These alternatives include other methods of power generation and not renewing the 
Executive Summary

xviii

STP operating licenses (the no-action alternative). Replacement power options considered 

were as follows:

• new nuclear generation,

• natural gas-fired combined-cycle generation,

• supercritical coal-fired generation,

• combination alternative, and

• purchased power.

The NRC staff initially considered many additional alternatives for analysis as alternatives to 

license renewal of STP; these were later dismissed due to technical, resource availability, or 

commercial limitations that currently exist and that the NRC staff believes are likely to continue 

to exist when the existing STP licenses expire. The no-action alternative by the NRC staff, and 

the effects it would have, were also considered. Where possible, the NRC staff evaluated 

potential environmental impacts for these alternatives located both at the STP site and at some 

other unspecified alternate location. Alternatives considered, but dismissed, were as follows:

• offsite nuclear-, gas-, and coal-fired capacity,

• energy conservation and energy efficiency,

• wind power,

• solar power,

• hydroelectric power,

• wave and ocean energy,

• geothermal power,

• municipal solid waste,

• biomass,

• biofuels,

• oil-fired power,

• fuel cells, and

• delayed retirement.

The NRC staff evaluated each alternative using the same impact areas that were used in 

evaluating impacts from license renewal.

RECOMMENDATION

The NRC’s preliminary recommendation is that the adverse environmental impacts of license 

renewal for STP are not great enough to deny the option of license renewal for energy-planning 

decisionmakers. This recommendation is based on the following:

• analysis and findings in the GEIS,

• ER submitted by STPNOC,

• consultation with Federal, state, local, and tribal government agencies,
Executive Summary 

xix

• the NRC staff’s own independent review, and

• consideration of public comments received during the scoping process.

xxi

ABBREVIATIONS AND ACRONYMS

AADT average annual daily traffic

ABWR advanced boiling-water reactor

ac acre

ac-ft acre-foot

ACHP Advisory Council on Historic Preservation

ADAMS Agencywide Documents Access and Management System

AEA Atomic Energy Act of 1954

AEO Annual Energy Outlook

AFW auxiliary feedwater

ALARA as low as is reasonably achievable

AMP aging management program

AOC averted offsite property damage costs

AOSC averted onsite costs

APE area of potential effect

AQCR air quality control region

ASME American Society of Mechanical Engineers

ATWS anticipated transient without scram

BACT best available control technology

BEG Bureau of Economic Geology

BGS below ground surface

BMP best management practice

Bq/l becquerels per liter

BTU British thermal unit

C Celsius

CAA Clean Air Act

CAES compressed air energy storage

CAPS Missouri Census Data Center Circular Area Profiling System

CCW component cooling water

CDF core damage frequency

CDM control drive mechanism
Abbreviations and Acronyms

xxii

Ceq carbon equivalent

CET containment event tree

CFR U.S. Code of Federal Regulations

cfs cubic feet per second

CLB current licensing basis

cm centimeter

CO2 carbon dioxide

COE cost of enhancement

COL combined license

Corps U.S. Army Corps of Engineers

CPGCD Coastal Plains Groundwater Conservation District

CWA Clean Water Act

CWIS cooling water intake structure

DBA design-basis accident

dBA decibel A-weighting

DG diesel generator

DMR discharge monitoring report

DOE U.S. Department of Energy

DSEIS draft supplemental environmental impact statement

DSHS Department of State Health Services

DWS drinking water standard

ECP essential cooling pond

ECW essential cooling water

ECWIS essential cooling water intake structure

EFH essential fish habitat

EIA Energy Information Administration

EIS environmental impact statement

ELF extremely low frequency

EMF electromagnetic field

EO Executive Order

EOE Encyclopedia of Earth

EPA U.S. Environmental Protection Agency

EPCRA Emergency Planning and Community Right-to-Know Act
Abbreviations and Acronyms 

xxiii

EPRI Electric Power Research Institute

EPZ emergency planning zone

ER Environmental Report

ERCOT Electric Reliability Council of Texas

ESA Endangered Species Act

ESRP environmental standard review plan

F Fahrenheit

F&O facts and observations

FES final environmental statement

FIP Federal Implementation Plan

FM Farm-to-Market

FR Federal Register

FRN Federal Register Notice

FSAR final safety analysis report

FSEIS final supplemental environmental impact statement

ft foot

ft3 cubic foot

ft/s feet per second

FWS U.S. Fish and Wildlife Service

g gram

gal gallon

GCBO Gulf Coast Bird Observatory

GCC global climate change

GE General Electric

GEA Geothermal Energy Association

GEIS generic environmental impact statement

GHG greenhouse gas

GIWW Gulf Intercoastal Waterway

GL generic letter

GMFMC Gulf of Mexico Fishery Management Council

gpd gallons per day

gpm gallons per minute

GWMS gaseous waste management system
Abbreviations and Acronyms

xxiv

ha hectare

HAP hazardous air pollutant

HARC Houston Advanced Research Center

hr hour

HVAC heating, ventilation, and air conditioning

Hz hertz

IAEA International Atomic Energy Agency

IEEE Institute of Electrical and Electronics Engineers, Inc.

IES Institute of Educational Sciences

IGCC integrated gasification combined cycle

in. inch

IPA integrated plant assessment

IPCC Intergovernmental Panel on Climate Change

IPE individual plant examination

IPEEE individual plant examination of external events

ISD independent school district

ISEPA Iowa Stored Energy Plant Agency

ISLOCA interfacing system loss-of-coolant accident

kg kilogram

km kilometer

km2 square kilometer

kV kilovolt

kWh kilowatt hour

L/min liters per minute

lb pound

LCRA Lower Colorado River Authority

LCRWPG Lower Colorado River Water Planning Group

LERF large early release frequency

LLNL Lawrence Livermore National Laboratory

LLW low-level waste

LOCA loss-of-coolant accident
Abbreviations and Acronyms 

xxv 

LOOP loss of offsite power

LRA license renewal application

LWPS liquid waste processing system

m meter

m3 cubic meter

m3/s cubic meters per second

mA milliampere

MAAP Modular Accident Analysis Program

MACCS2 MELCOR Accident Consequence Code System 2

MACR maximum averted cost-risk

MBTA Migratory Bird Treaty Act

MCR main cooling reservoir

MDC main drainage channel

mg/l milligrams per liter

mgd millions of gallons per day

mGy milligray

mi mile

min minute

MIT Massachusetts Institute of Technology

mm millimeter

MMI Modified Mercalli Intensity

MMS U.S. Minerals Management Service

mo month

mrad millirad

mrem millirem

MSA Magnuson-Stevens Fishery Conservation and Management Act

MSL mean sea level

mSv millisievert

MT metric ton

MW megawatt

MWd megawatt day

MWe megawatt electric

MWt megawatt thermal
Abbreviations and Acronyms

xxvi 

NAAQS National Ambient Air Quality Standards

NASS National Agriculture Statistics Service

NCES National Center for Education Statistics

NEA Nuclear Energy Agency

NEI Nuclear Energy Institute

NEPA National Environmental Policy Act

NESC National Electrical Safety Code

NETL National Energy Technology Laboratory

NGCC natural gas-fired combined-cycle

NHPA National Historic Preservation Act

NIEHS National Institute of Environmental Health Sciences

NMFS National Marine Fisheries Service

NPCC Northwest Power and Conservation Council

NPDES National Pollutant Discharge Elimination System

NRC U.S. Nuclear Regulatory Commission

NRCS Natural Resources Conservation Service

NREL National Renewable Energy Laboratory

NRHP National Register of Historic Places

NRR Office of Nuclear Reactor Regulation

NWS National Weather Service

OECD Organization for Economic Co-operation and Development

OMB Office of Management and Budget

OPSB Ohio Power and Siting Board

PACR potential averted cost-risk

pCi/L picocuries per liter

PDP positive displacement pump

PGA peak ground acceleration

PM10 particulate matter, ≤10 μm

PM2.5 particulate matter, ≤2.5 μm

PNNL Pacific Northwest National Laboratory

POST Parliamentary Office of Science and Technology

PRA probabilistic risk assessment

PSD prevention of significant deterioration
Abbreviations and Acronyms 

xxvii 

PWR pressurized-water reactor

RAI request for additional information

RCB reactor containment building

RCP reactor coolant pump

RCRA Resources Conservation and Recovery Act

RCS reactor coolant system

rem roentgen equivalent man

REMP Radiological Environmental Monitoring Program

RG regulatory guide

RMPF reservoir makeup pumping facility

RMTS risk managed technical specification

ROI region of influence

ROW right-of-way

RPC replacement power costs

RRW risk reduction worth

RTC Report to Congress

SAMA severe accident mitigation alternative

SAR safety analysis report

SAWS San Antonio Water System

SBDG standby diesel generator

SCR selective catalytic reduction

SEIS supplemental environmental impact statement

SER safety evaluation report

SG steam generator

SGTR steam generator tube rupture

SHPO State Historic Preservation Office

SIP State Implementation Plan

SNL Sandia National Laboratory

SOARCA State-of-the-Art Reactor Consequence Analysis

SPDES State Pollutant Discharge Elimination System

SSC system, structure, and component

SSE safe shutdown earthquake

STP South Texas Project
Abbreviations and Acronyms

xxviii 

STPNOC South Texas Project Nuclear Operating Company

Sv sievert

SWPS solid waste processing system

TAC Texas Administrative Code

TCEQ Texas Commission on Environmental Quality

TCPA Texas Comptroller of Public Accounts

TDS total dissolved solids

THC Texas Historical Commission

TMMSN Texas Marine Mammal Stranding Network

TPDES Texas Pollutant Discharge Elimination System

TPWD Texas Parks and Wildlife Department

tpy tons per year

TS technical specification

TSC Technical Support Center

TSECO Texas State Energy Conservation Office

TSHA Texas State Historical Association

TSP total suspended particles

TSWGW Texas Saltwater and Fishing Guides Web

TWDB Texas Water Development Board

USCB U.S. Census Bureau

USGS U.S. Geological Survey

VOC volatile organic compound

WEG Wild Earth Guardians

WMA Wildlife Management Area

WOE weight-of-evidence

WSEC White Stallion Energy Center

yr year
1-1 

1 1.0 PURPOSE AND NEED FOR ACTION

2 Under the U.S. Nuclear Regulatory Commission’s (NRC’s) environmental protection regulations 

3 in Title 10, Part 51, of the Code of Federal Regulations (10 CFR 51)—which implement the 

4 National Environmental Policy Act (NEPA)—issuance of a new nuclear power plant operating 

5 license requires the preparation of an environmental impact statement (EIS).

6 The Atomic Energy Act of 1954 (AEA) specifies that licenses for commercial power reactors can 

7 be granted for up to 40 years. NRC regulations (10 CFR 54.31) allow for an option to renew a 

8 license for up to an additional 20 years. The initial 40-year licensing period was based on 

9 economic and antitrust considerations rather than on technical limitations of the nuclear facility.

10 The decision to seek a license renewal rests entirely with nuclear power facility owners and, 

11 typically, is based on the facility’s economic viability and the investment necessary to continue 

12 to meet NRC safety and environmental requirements. The NRC makes the decision to grant or 

13 deny license renewal based on whether the applicant has demonstrated that the environmental 

14 and safety requirements in the agency’s regulations can be met during the period of extended 

15 operation.

1.1

17 STP Nuclear Operating Company (STPNOC) initiated the proposed Federal action by 

18 submitting an application for license renewal of South Texas Project (STP), Units 1 and 2, for 

19 which the existing licenses (NPF-76 and NPF-80) expire on August 20, 2027, and 

20 December 15, 2028, respectively. The NRC’s Federal proposed action is the decision whether 

21 to renew the licenses for an additional 20 years.

16 Proposed Federal Action

1.2

23 The purpose and need for the proposed action (issuance of a renewed license) is to provide an 

24 option that allows for power generation capability beyond the term of a current nuclear power 

25 plant operating license to meet future system generating needs, as such needs may be 

26 determined by other energy-planning decisionmakers. This definition of purpose and need 

27 reflects the NRC’s recognition that, unless there are findings in the safety review required by the 

28 AEA or findings in the NEPA environmental analysis that would lead the NRC to reject a license 

29 renewal application (LRA), the NRC does not have a role in the energy-planning decisions of 

30 State regulators and utility officials as to whether a particular nuclear power plant should 

31 continue to operate.

22 Purpose and Need for the Proposed Federal Action

32 If the renewed license is issued, State regulatory agencies and STPNOC will ultimately decide 

33 whether the plant will continue to operate based on factors such as the need for power or other 

34 matters within the State’s jurisdiction or the purview of the owners. If the operating license is 

35 not renewed, then the facility must be shut down on or before the expiration dates of the current 

36 operating licenses—August 20, 2027, and December 15, 2028, respectively. 

1.3

38 STPNOC submitted an Environmental Report (ER) (STPNOC 2010b) as part of its LRA

39 (STPNOC 2010a) in October 2010. After reviewing the LRA and ER for sufficiency, the NRC 

40 staff published a Federal Register Notice of Acceptability and Opportunity for Hearing 

41 (76 FRN 2426) on January 13, 2011. Then, on January 31, 2011, the NRC published another 

37 Major Environmental Review Milestones
Purpose and Need for Action

1-2 

1 notice in the Federal Register (76 FR 5410) on the intent to conduct scoping, thereby beginning 

2 the 60-day scoping period.

3 The NRC staff held two public scoping meetings on March 2, 2011, in Bay City, Texas. The 

4 comments received during the scoping process are presented in their entirety in “Environmental 

5 Impact Statement Scoping Process, Summary Report, South Texas Project, Units 1 and 2, Bay 

6 City,” published in 2012 (NRC 2012). The staff presents comments considered to be within the 

7 scope of the environmental license renewal review and the NRC responses in Appendix A of 

8 this supplemental environmental impact statement (SEIS). 

9 In order to independently verify information provided in the ER, the NRC staff conducted a site 

10 audit at STP, Units 1 and 2, in July 2011. During the site audit, the staff met with plant 

11 personnel, reviewed specific documentation, toured the facility, and met with interested Federal, 

12 State, and local agencies. A summary of that site audit and the attendees is contained in the 

13 Audit Summary Report, published in August 2011 (NRC 2011).

14 Upon completion of the scoping period and site audit, the NRC staff compiled its findings in this

15 draft SEIS (Figure 1–1). This document is made available for public comment for 45 days. 

16 During this time, the staff will host public meetings and collect public comments. Based on the 

17 information gathered, it will amend the draft SEIS findings, as necessary, and publish the final 

18 SEIS for license renewal. 

19 Figure 1–1. Environmental Review Process

20 The NRC has established a license renewal review process that can be completed in a 

21 reasonable period with clear requirements to assure safe plant operation for up to an additional 

22 20 years of plant life. The NRC staff conducts the safety review simultaneously with the 

23 environmental review. The staff documents the findings of the safety review in a safety 

24 evaluation report (SER). The findings in the SEIS and the SER are both factors in the NRC’s 

25 decision to either grant or deny the issuance of a renewed license. 
Purpose and Need for Action

1-3 

1.4

2 The NRC staff performed a generic assessment of the environmental impacts associated with 

3 license renewal to improve the efficiency of its license renewal review. The Generic 

4 Environmental Impact Statement for License Renewal of Nuclear Power Plants (GEIS), 

5 NUREG-1437 (NRC 1996, 1999), documented the results of the staff’s systematic approach to 

6 evaluate the environmental consequences of renewing the licenses of individual nuclear power 

7 plants and operating them for an additional 20 years. The staff analyzed in detail and resolved 

8 those environmental issues that could be resolved generically in the GEIS.

1 Generic Environmental Impact Statement

9 The GEIS establishes 92 separate issues for the NRC staff to independently verify. Of these 

10 issues, the NRC staff determined that 69 are generic to all plants (Category 1) while 21 issues 

11 do not lend themselves to generic consideration (Category 2). Two other issues remain 

12 uncategorized (environmental justice and chronic effects of electromagnetic fields). The staff 

13 evaluated these issues on a site-specific basis (along with the Category 2 issues). Appendix B 

14 provides the list of all 92 issues. 

15 For each potential environmental issue, in the GEIS, the NRC staff performs the following: 

16 • describes the activity that affects the environment, 

17 • identifies the population or resource that is affected, 

18 • assesses the nature and magnitude of the impact on the affected population 

19 or resource, 

20 • characterizes the significance of the effect for both beneficial and adverse 

21 effects, 

22 • determines whether the results of the analysis apply to all plants, and

23 • considers whether additional mitigation measures would be warranted for 

24 impacts that would have the same significance level for all plants. 

25 The NRC’s standard of significance for impacts was established using the Council on 

26 Environmental Quality (CEQ) terminology for “significant.” The NRC established three levels of 

27 significance for potential impacts—SMALL, MODERATE, and LARGE, as defined below.

28 SMALL: Environmental effects are not 

29 detectable or are so minor that they will neither 

30 destabilize nor noticeably alter any important 

31 attribute of the resource.

32 MODERATE: Environmental effects are 

33 sufficient to alter noticeably, but not to destabilize, 

34 important attributes of the resource.

35 LARGE: Environmental effects are clearly noticeable and are sufficient to destabilize important 

36 attributes of the resource.

37 The GEIS includes a determination of whether the analysis of the environmental issue could be 

38 applied to all plants and whether additional mitigation measures would be warranted 

39 (Figure 1–2). Issues are assigned a Category 1 or a Category 2 designation. As set forth in the 

40 GEIS, Category 1 issues are those that meet the following criteria:

Significance indicates the importance of likely 

environmental impacts and is determined by 

considering two variables: context and intensity. 

Context is the geographic, biophysical, and social 

context in which the effects will occur. 

Intensity refers to the severity of the impact, in 

whatever context it occurs.
Purpose and Need for Action

1-4 

1 • The environmental impacts associated with the issue have been determined 

2 to apply either to all plants or, for some issues, to plants having a specific 

3 type of cooling system or other specified plant or site characteristics.

4 • A single significance level (i.e., SMALL, MODERATE, or LARGE) has been 

5 assigned to the impacts (except for collective offsite radiological impacts from 

6 the fuel cycle and from high-level waste and spent fuel disposal).

7 • Mitigation of adverse impacts associated with the issue has been considered 

8 in the analysis, and it has been determined that additional plant-specific 

9 mitigation measures are likely not to be sufficiently beneficial to warrant 

10 implementation.

11 Figure 1–2. Environmental Issues Evaluated For License Renewal

12 In the GEIS, 92 issues were evaluated. 

13 A site-specific analysis is required for 23 of those 92 issues

14 For generic issues (Category 1), no additional site-specific analysis is required in this SEIS

15 unless new and significant information is identified. The process for identifying new and 

16 significant information is presented in Chapter 4. Site-specific issues (Category 2) are those 

17 that do not meet one or more of the criteria of Category 1 issues; therefore, additional 
Purpose and Need for Action

1-5 

1 site-specific review for these issues is required. The results of that site-specific review are 

2 documented in the SEIS. 

3 In summary, the NRC staff evaluated 92 issues in the GEIS. Based on the findings of the GEIS, 

4 a site-specific analysis is required for 23 of those 92 issues and is addressed in the SEIS.

1.5

6 The SEIS presents an analysis that considers the environmental effects of the continued 

7 operation of STP, Units 1 and 2, alternatives to license renewal, and mitigation measures for 

8 minimizing adverse environmental impacts. Chapter 8 contains analysis and comparison of the 

9 potential environmental impacts from alternatives while Chapter 9 presents the preliminary 

10 recommendation to the NRC (the Commission) on whether or not the environmental impacts of 

11 license renewal are so great that preserving the option of license renewal would be 

12 unreasonable. The final recommendation will be made after consideration of comments 

13 received on this draft SEIS during the public comment period. 

5 Supplemental Environmental Impact Statement

14 In the preparation of this SEIS for STP, Units 1 and 2, the NRC staff carried out the following 

15 activities: 

16 • reviewed the information provided in the STPNOC’s ER; 

17 • consulted with other Federal, State, local agencies, and Tribal nations; 

18 • conducted an independent review of the issues during site audit; and

19 • considered the public comments received for the review (during the scoping 

20 process and, subsequently, on this draft SEIS).

21 New information can be identified from many 

22 sources, including the applicant, the NRC, other 

23 agencies, or public comments. If a new issue is 

24 revealed, it is first analyzed to determine whether 

25 it is within the scope of the license renewal 

26 environmental evaluation. If the new issue is not 

27 addressed in the GEIS, the NRC staff would determine the significance of the issue and 

28 document the analysis in the SEIS.

1.6

30 During the scoping process, no Federal, State, or local agencies were identified as cooperating 

31 agencies in the preparation of this SEIS.

29 Cooperating Agencies

1.7

33 The Endangered Species Act of 1973, as amended; the Magnuson–Stevens Fisheries 

34 Management Act of 1996, as amended; and the National Historic Preservation Act of 1966 

35 require that Federal agencies consult with applicable State and Federal agencies and groups 

36 prior to taking action that may affect endangered species, fisheries, or historic and 

37 archaeological resources, respectively. The NRC consulted with the following agencies and 

38 groups (Appendix D to this SEIS includes copies of consultation documents):

32 Consultations

39 • Advisory Council on Historic Preservation (ACHP), 

40 • National Marine Fisheries Service (NMFS), 

New and significant information either identifies 

a significant environmental issue that was not 

covered in the GEIS or was not considered in the 

analysis in the GEIS and leads to an impact 

finding that is different from the finding presented 

in the GEIS.
Purpose and Need for Action 

1-6 

1 • State Historic Preservation Office (SHPO), 

2 • U.S. Fish and Wildlife Service (USFWS), 

3 • Ysleta del Sur Pueblo, 

4 • Alabama-Coushatta Tribe, 

5 • Kiowa Tribe of Oklahoma, 

6 • Comanche Nation, 

7 • Tonkawa Tribe of Oklahoma, 

8 • Apalachicola Creek, 

9 • Lipan Apache Tribe of Texas, 

10 • Lipan Apache Band of Texas, 

11 • Tap Pulam-Coahuiltecan Nation, 

12 • Kickapoo Traditional Council, 

13 • Pamaque Clan of Coahuila Y Tejas, and 

14 • Apalachicola Band of Creek Indians. 

1.8

16 During the course of the environmental review, the NRC staff contacted Federal, State, regional, 

17 local, and Tribal agencies listed in Section 1.7. Appendix E contains a chronological list of all 

18 documents sent and received during the environmental review.

15 Correspondence

19 In addition, Chapter 11 provides a list of persons who requested and received a copy of this 

20 SEIS. 

1.9

22 STPNOC is responsible for complying with all NRC regulations and other applicable Federal, 

23 State, and local requirements. Appendix H of the GEIS describes some of the major applicable 

24 Federal statutes. 

21 Status of Compliance

25 There are numerous permits and licenses issued by Federal, State, and local authorities for 

26 activities at STP, Units 1 and 2. Appendix C contains further discussion by the staff about 

27 status of compliance. Regarding Coastal Zone Management Act (CZMA) compliance status, 

28 pursuant to Section 506.11(13) of Texas Administrative Code, STPNOC has obtained and 

29 maintained satisfactorily a consistency certification in accordance with the CZMA (Section 2.3 

30 contains further discussion about CZMA compliance status for STP license renewal). 

1.10

32 10 CFR 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental protection

33 regulations for domestic licensing and related regulatory functions.”

31 References

34 10 CFR 54. Code of Federal Regulations, Title 10, Energy, Part 54, “Requirements for renewal 

35 of operating licenses for nuclear power plants.”
Purpose and Need for Action

1-7 

1 76 FR 2426. U.S. Nuclear Regulatory Commission. “Notice of Acceptance for Docketing of the 

2 Application and Notice of Opportunity for Hearing Regarding Renewal of Facility Operating 

3 License Numbers NPF–76 and NPF–80 for an Additional 20-Year Period, STP Nuclear

4 Operating Company, South Texas Project, Units 1 and 2.” Federal Register. Volume 76(9): 

5 2426–2428. January 13, 2011.

6 76 FRN 5410. U.S. Nuclear Regulatory Commission. “STP Nuclear Operating Company; 

7 Notice of Intent To Prepare an Environmental Impact Statement and Conduct the Scoping 

8 Process for South Texas Project, Units 1 and 2.” Federal Register. Volume 76(20): 

9 5410–5411. January 31, 2011.

10 [AEA] Atomic Energy Act of 1954, as amended. 42 U.S.C. §2011, et seq.

11 Endangered Species Act of 1973, as amended. 16 U.S.C. §1531, et seq.

12 Magnuson–Stevens Fishery Conservation and Management Act, as amended. 

13 16 U.S.C. §1801 et seq.

14 [NEPA] National Environmental Policy Act of 1969, as amended. 42 U.S.C. §4321, et seq.

15 National Historic Preservation Act of 1966. 16 U.S.C. §470, et seq.

16 [NRC] U.S. Nuclear Regulatory Commission. 1996. Generic Environmental Impact Statement 

17 for License Renewal of Nuclear Plants. Washington, DC: NRC. NUREG-1437. May 1996. 

18 ADAMS Nos. ML040690705 and ML040690738.

19 [NRC] U.S. Nuclear Regulatory Commission. 1999. Section 6.3, Transportation, Table 9.1, 

20 Summary of findings on NEPA issues for license renewal of nuclear power plants. In: Generic 

21 Environmental Impact Statement for License Renewal of Nuclear Plants. Washington, DC: 

22 NRC. NUREG-1437, Volume 1, Addendum 1. August 1999. ADAMS No. ML040690720.

23 [NRC] U.S. Nuclear Regulatory Commission. 2011. Summary of site audit related to the 

24 review of the license renewal application for South Texas Project, Units 1 and 2. 

25 August 4, 2011. ADAMS No. ML11196A005. 

26 [NRC] U.S. Nuclear Regulatory Commission. 2012. Environmental Impact Statement Scoping 

27 Process, Summary Report, South Texas Project, Units 1 and 2, Bay City, TX. Washington, DC: 

28 NRC. 2012. ADAMS No. ML11153A082. 

29 [STPNOC] South Texas Plant Nuclear Operating Company. 2010a. “South Texas Project, 

30 Units 1 and 2, Docket Nos. STN 50–498, STN 50–499, License Renewal Application.” 

31 October 25, 2010. ADAMS No. ML103010257.

32 [STPNOC] South Texas Plant Nuclear Operating Company. 2010b. “South Texas Project, 

33 Applicant’s Environmental Report—Operating License Renewal Stage, South Texas Project 

34 Units 1 & 2.” September 2010. ADAMS No. ML103010263.

2-1 

2-1 

1 2.0 AFFECTED ENVIRONMENT

2 South Texas Project (STP) is located in Matagorda County, Texas, approximately 70 mi

3 (110 km) south-southwest of Houston. The plant consists of two reactor units. Each nuclear 

4 reactor is a pressurized-water reactor (PWR) with steam generators producing steam that turns 

5 turbines to generate electricity. For purposes of the evaluation in this report, the “affected 

6 environment” is the environment that currently exists at and around STP. Because existing 

7 conditions are at least partially the result of past construction and operation at the plant, the 

8 impacts of these past and ongoing actions and how they have shaped the environment are 

9 presented here. The facility and its operation are described in Section 2.1, and the affected 

10 environment is presented in Section 2.2.

2.1

12 STP is a two-unit, nuclear-powered steam electric generating facility that began commercial 

13 operation in August 1988 (Unit 1) and June 1989 (Unit 2). The nuclear reactor for each unit is a 

14 Westinghouse PWR, producing a reactor core rated thermal power of 3,853 megawatts-thermal 

15 (MWt). The nominal net electrical capacity is 1,250 megawatts-electric (MWe). In this 

16 supplemental environmental impact statement (SEIS), the use of “STP” is referring to the site 

17 where the existing “STP, Units 1 and 2” are located. The use of “STPNOC” is referring to the 

18 applicant (STP Nuclear Operating Company) who submitted the license renewal application

19 (LRA). The use of “STP, Units 1 and 2” is referring to the distinction between the existing 

20 reactor units and the proposed new reactor units, “STP, Units 3 and 4.” 

11 Facility Description

21 2.1.1 Reactor and Containment Systems

22 The nuclear steam supply system at STP is a four-loop Westinghouse PWR. The reactor core 

23 heats water, which is pumped to four steam generators where the heat boils the water on the 

24 shell-side into steam that is routed to the turbines. The steam turns the turbines, which are 

25 connected to the electrical generator. The Units 1 and 2 steam generators were replaced in 

26 2008 and 2009, respectively, with new Westinghouse steam generators.

27 The nuclear fuel is low-enriched uranium dioxide with enrichments less than 5 percent by weight 

28 uranium-235 and fuel burnup levels with a batch average of approximately 

29 45,000 megawattdays (MWd) per metric ton uranium at discharge. Maximum burnup would not 

30 exceed 60,000 MWd per metric ton uranium. STP operates on an 18-month refueling cycle.

31 The reactor, steam generators, and related systems are enclosed in a containment building. 

32 The containment building is a post-tensioned, reinforced concrete cylinder with a slab base and 

33 a hemispherical dome. A welded steel liner is attached to the inside face of the concrete shell 

34 to ensure a high degree of leak tightness. In addition, the 4-ft (1.2-m)–thick concrete walls 

35 serve as a radiation shield.

36 2.1.2 Radioactive Waste Management

37 STP uses liquid, gaseous, and solid waste 

38 processing systems to collect and treat, as 

39 needed, radioactive materials that are produced 

40 as by-products of plant operations. These 

41 materials are produced in the form of 

By design, the operation of nuclear power plants 

is expected to result in small releases of 

radiological effluents (gaseous, liquid, and solid) 

through controlled processes. However, releases 

must meet stringent NRC and EPA regulatory 

limits.
Affected Environment 

2-2 

1 (a) activation products resulting from irradiation of reactor water and impurities, principally 

2 metallic corrosive products, therein and (b) fission products resulting from their migration 

3 through the fuel cladding. Radioactive materials in liquid and gaseous effluents (controlled 

4 releases from STP) are reduced to levels that ensure compliance with NRC radiation protection 

5 regulations in Title 10, Part 20, of the U.S. Code of Federal Regulations (10 CFR Part 20), and 

6 they are as low as is reasonably achievable (ALARA), in accordance with Appendix I to 

7 10 CFR Part 50.

8 Reactor fuel assemblies that have exhausted some of their fissile uranium content (related to 

9 the ability to sustain nuclear criticality chain reaction) are referred to as spent fuel (or used fuel). 

10 Spent fuel assemblies are removed from the reactor core and replaced by new fuel assemblies 

11 during routine refueling outages, typically every 18 months. The spent fuel assemblies are then 

12 stored in the spent fuel pool.

13 Systems used at STP to process radioactive liquid, gaseous, and solid wastes are described in 

14 the following sections.

15 2.1.2.1 Radioactive Gaseous Waste System

16 The objectives of the gaseous waste management system (GWMS) are to process and control 

17 the release of radioactive gaseous effluents into the environment to be within the requirements 

18 of 10 CFR Part 20 and to be consistent with the ALARA guidelines set forth in Appendix I to 

19 10 CFR Part 50. The GWMS also removes fission product gases from the reactor coolant 

20 system and from equipment and piping (i.e., reduces the amount of radioactivity from the gases

21 before they are released into the environment). The GWMS is designed so that radiation 

22 exposure to plant workers is within NRC dose limits in 10 CFR 20.1201 and ALARA.

23 The GWMS processes the waste gas to control and limit the amount of radioactive noble gas 

24 and iodine released into the environment. An inlet header water removal system removes water 

25 vapor and heat from the gas stream prior to processing the gas through charcoal beds. The 

26 charcoal beds are designed to delay the passage of the gases, which allows for radioactive 

27 decay of the noble gases and adsorption of radioiodine as the gas stream moves through the 

28 charcoal beds. At the end of the charcoal bed, the gas is filtered by high efficiency filters to 

29 remove charcoal dust. There is also a radiation monitor that measures the radioactivity in the 

30 waste gas and can automatically terminate the release in the event radioactivity exceeds 

31 predetermined levels.

32 The primary sources of radioactive gas in the plant are as follows: 

33 • the turbine generator building process vents, 

34 • the auxiliary feedwater pump turbine exhaust, which is vented directly to the 

35 atmosphere through the isolation valve cubicle process vent, 

36 • the reactor containment building ventilation system, 

37 • the mechanical auxiliary building, 

38 • the fuel handling building ventilation system, and

39 • the reactor coolant gases.

40 2.1.2.2 Radioactive Liquid Waste System

41 The function of STPNOC’s liquid waste processing system (LWPS) is to collect and process 

42 radioactive liquid wastes to reduce radioactivity and chemical concentrations to levels 

43 acceptable for discharge to the environment or to recycle the liquids for use in plant systems.
Affected Environment

2-3 

1 The principal objectives of the LWPS are to collect liquid wastes that may contain radioactive 

2 material and to maintain sufficient processing capability so that liquid waste may be discharged 

3 to the environment below the regulatory limits of 10 CFR Part 20 and consistent with the 

4 ALARA guidelines in Appendix I to 10 CFR Part 50.

5 Sources of liquid waste sent to the LWPS include floor drains, equipment drains, laundry and 

6 hot shower drains, and contaminated wastes from plant systems and components. Processing 

7 of the liquid waste is performed using several different methods including filtration, 

8 demineralization, evaporation, or a combination of the three methods.

9 Liquid releases from the plant are made in accordance with NRC radiation protection standards 

10 in 10 CFR Part 20 and the ALARA guidelines set forth in Appendix I to 10 CFR Part 50. The 

11 waste is routed through a monitor that measures the radioactivity and can automatically 

12 terminate the release in the event radioactivity exceeds predetermined levels. The liquid waste 

13 is discharged into the main cooling reservoir (MCR). The entire MCR is within the STP site 

14 boundary, and the public is prohibited from access to the MCR.

15 2.1.2.3 Radioactive Solid Waste Processing Systems

16 The solid waste processing system (SWPS) is designed to process, package, and store the 

17 solid radioactive wastes generated by plant operations until they are shipped off site to a vendor 

18 for further processing or for permanent disposal at a licensed burial facility or both. The SWPS 

19 is designed to meet the following objectives:

20 • to collect process, package, temporary store, and prepare the waste for 

21 shipment; 

22 • to maintain radiation exposes to plant personnel within the dose limits of 

23 10 CFR Part 20.1201 and ALARA; 

24 • to package and transport the waste in compliance with NRC regulations 

25 10 CFR Parts 61 and 71 and the U.S. Department of Transportation

26 regulations 49 CFR Parts 170 through 179; and

27 • to stabilize wet waste using either an onsite or offsite system from a qualified 

28 vendor.

29 The permanently installed portion of the SWPS is located within the mechanical-electrical 

30 auxiliary building. Identical systems containing the following major subsystems are used for 

31 STP, Units 1 and 2: 

32 • Concentrate storage tank and transfer subsystem—This subsystem includes 

33 a 5,000-gallon storage tank equipped with a mixer, heat tracing, and level 

34 controls to prevent overflows. The applicant states that this system is 

35 currently not in use.

36 • Spent resin transfer subsystem—This system is used to transfer spent resin 

37 filter media to a vendor-supplied processing system.

38 • Expended cartridge filter transfer subsystem—This system handles filter 

39 cartridges used to process radioactive liquid wastes. The system uses

40 shielding and long-handled tools to safely handle the filters for insertion into a 

41 shielded cask that will be transported to a disposal facility.

42 • Overhead crane subsystem—This is a remotely operated 7 1⁄2-ton overhead 

43 bridge crane with automatic grapples to move loaded containers from the 
Affected Environment 

2-4 

1 storage areas to the truck loading area and to stabilize wet waste using either 

2 an onsite or offsite system from a qualified vendor.

3 • Dry active waste area—This area is used to sort and package dry active 

4 waste. The waste is typically sent to an offsite vendor for volume reduction 

5 prior to disposal.

6 • Chemical addition subsystem—This subsystem provides chemical 

7 adjustment of liquids to maintain pH control for efficient processing.

8 • Vendor-supplied onsite subsystem—This subsystem consists of control 

9 panels used to control dewatering pumps, fill and dewatering heads, level 

10 controls, and monitoring instruments.

11 Radioactive waste is stored within plant buildings until it is shipped off site for further processing 

12 by a vendor or disposal or both. The storage areas have restricted access and shielding to 

13 reduce radiation rates to plant workers. The radioactive waste is divided into high activity and 

14 low activity storage areas. Separation of the high activity storage area from the building exterior 

15 by the low activity area provides for a reduction in radiation levels to plant workers in the truck 

16 loading area.

17 The Texas Low-Level Radioactive Waste Disposal Compact Facility, located in Andrews 

18 County, Texas, opened on November 10, 2011. The facility is licensed by the State of Texas to 

19 dispose of Class A, B, and C low-level waste (LLW). This LLW disposal facility is available to 

20 STP for the disposal of its LLW. With the availability of this disposal facility, the current LLW 

21 handling and storage facilities are expected to be adequate to handle LLW waste generated 

22 during the license renewal term.

23 In the event of an interruption in LLW disposal capability, STP has the ability to store its waste 

24 on site. STP has an onsite staging facility, located west of STP Unit 2. This facility can provide 

25 a staging area for the waste for up to 5 years of operation of both reactor units.

26 2.1.3 Nonradiological Waste Management

27 STP generates nonradioactive wastes as part of routine plant maintenance, cleaning activities, 

28 and plant operations. In general, Resources Conservation and Recovery Act (RCRA) waste 

29 regulations governing the disposal of solid and hazardous waste are contained in 

30 40 CFR Parts 239 through 299. Specifically, 40 CFR Parts 239 through 259 contain regulations 

31 for solid (nonhazardous) waste, and 40 CFR Parts 260 through 279 contain regulations for 

32 hazardous waste. RCRA, Subtitle C, establishes a system for controlling hazardous waste from 

33 “cradle to grave,” and RCRA, Subtitle D, encourages states to develop comprehensive plans to 

34 manage nonhazardous solid waste and mandates minimum technological standards for 

35 municipal solid waste landfills. Texas State RCRA regulations are administered by the Texas 

36 Commission on Environmental Quality (TCEQ) and address the identification, generation, 

37 minimization, transportation, and final treatment, storage, or disposal of hazardous and 

38 nonhazardous waste.

39 2.1.3.1 Nonradioactive Waste Streams

40 STP generates solid waste, defined by the RCRA, as part of routine plant maintenance, 

41 cleaning activities, and plant operations. Texas administers the RCRA Program in Texas 

42 Administrative Code (TAC) 335.

43 EPA classifies certain nonradioactive wastes as hazardous based on characteristics including 

44 ignitability, corrosivity, reactivity, or toxicity (hazardous wastes are listed in 40 CFR Part 261). 

45 State-level regulators may add wastes to EPA’s list of hazardous wastes. RCRA supplies 
Affected Environment

2-5 

1 standards for the treatment, storage, and disposal of hazardous waste for hazardous waste 

2 generators (regulations are available in 40 CFR Part 262).

3 EPA recognizes the following main types of the hazardous waste generators (40 CFR 260.10) 

4 based on the quantity of the hazardous waste produced:

5 • large quantity generators that generate 2,200 lb (1,000 kg) per month or more 

6 of hazardous waste, more than 2.2 lb (1 kg) per month of acutely hazardous 

7 waste, or more than 220 lb (100 kg) per month of acute spill residue or soil; 

8 • small quantity generators that generate more than 220 lb (100 kg) but less 

9 than 2,200 lb (1,000 kg) of hazardous waste per month; and

10 • conditionally exempt small quantity generators that generate 220 lb (100 kg) 

11 or less per month of hazardous waste, 2.2 lb (1 kg) or less per month of 

12 acutely hazardous waste, or less than 220 lb (100 kg) per month of acute spill 

13 residue or soil.

14 TCEQ recognizes STP as a small quantity generator of hazardous wastes under TAC 335. STP 

15 hazardous wastes include waste oil, grease, electrohydraulic fluid, adhesives, liquid paint, and 

16 solvent for fuel blending and thermal energy recovery. Used oil diesel fuels and used oil filters 

17 are sent to a recycling vendor for re-processing. Lead-acid batteries are returned, when 

18 possible, to the original manufacturer for recycling or are shipped to a registered battery 

19 recycler.

20 EPA classifies several hazardous wastes as universal wastes; these include batteries, 

21 pesticides, mercury-containing items, and fluorescent lamps. TCEQ has incorporated EPA’s 

22 regulations (40 CFR Part 273) regarding universal wastes in TAC 335.261. Universal wastes 

23 produced by STP are disposed of or recycled in accordance with TCEQ regulations.

24 Conditions and limitations for wastewater discharge by STP are specified in Texas Pollution 

25 Discharge Elimination System (TPDES) Permit No. WQ0001908000. In 2009, STP applied for 

26 a renewal of this wastewater discharge permit and, at the writing of this supplemental 

27 environmental impact statement (SEIS), continues to work with TCEQ on its renewal. 

28 Radioactive liquid waste is addressed in Section 2.1.2 of this SEIS. Section 2.2.4 gives more 

29 information about STP TPDES permit and permitted discharges, including a discussion of the 

30 staff’s request for information about the STP TPDES permit status.

31 The Emergency Planning and Community Right-to-Know Act (EPCRA) requires applicable 

32 facilities to supply information about hazardous and toxic chemicals to local emergency planning 

33 authorities and EPA (42 USC 11001). On October 17, 2008, EPA finalized several changes to 

34 the Emergency Planning (Section 302), Emergency Release Notification (Section 304), and 

35 Hazardous Chemical Reporting (Sections 311 and 312) regulations (63 FR 31268). STP is 

36 subject to Federal EPCRA reporting requirements; thus, STP submits an annual Section 312 

37 (Tier II) report on hazardous substances to local emergency response agencies.

38 2.1.3.2 Pollution Prevention and Waste Minimization

39 The EPA encourages the use of environmental management systems (EMSs) for organizations 

40 to assess and manage the environmental impacts associated with their activities, products, and 

41 services in an efficient and cost-effective manner. The EPA defines an EMS as “a set of 

42 processes and practices that enable an organization to reduce its environmental impacts and 

43 increase its operating efficiency.” EMSs help organizations fully integrate a wide-range of 

44 environmental initiatives, establish environmental goals, and create a continuous monitoring 

45 process to help meet those goals. The EPA Office of Solid Waste especially advocates the use 
Affected Environment 

2-6 

1 of EMSs at RCRA-regulated facilities to improve environmental performance, compliance, and 

2 pollution prevention (EPA 2010a).

3 Related to the use of EMSs, STP has waste minimization measures in place currently, as 

4 verified during the STP site visit conducted by NRC in July 2011. In support of nonradiological 

5 waste-minimization efforts, EPA’s Office of Prevention and Toxics has established a 

6 clearinghouse that supplies information about waste management and technical and operational 

7 approaches to pollution prevention (EPA 2010c). The EPA clearinghouse can be used as a 

8 source for additional opportunities for waste minimization and pollution prevention at STP, as 

9 appropriate.

10 2.1.4 Plant Operation and Maintenance

11 Maintenance activities conducted at STP include inspection, testing, and surveillance to 

12 maintain the current licensing basis (CLB) of the facility and to ensure compliance with 

13 environmental and safety requirements. Various programs and activities currently exist at STP 

14 to maintain, inspect, test, and monitor the performance of facility equipment. These 

15 maintenance activities include inspection requirements for reactor vessel materials, boiler and 

16 pressure vessel inservice inspection and testing, the Maintenance Structures Monitoring 

17 Program, and maintenance of water chemistry.

18 Additional programs include those carried out to meet technical specification (TS) surveillance 

19 requirements, those implemented in response to the NRC generic communications, and various 

20 periodic maintenance, testing, and inspection procedures. Certain program activities are carried 

21 out during the operation of the unit, while others are carried out during scheduled refueling 

22 outages. Nuclear power plants must periodically discontinue the production of electricity for 

23 refueling, periodic inservice inspection, and scheduled maintenance. STP operates on an 

24 18-month refueling cycle.

25 2.1.5 Power Transmission System

26 Nine 345-kV lines were constructed specifically to connect STP to the regional power grid. 

27 These lines share transmission line corridors and are owned by four service providers: 

28 American Electric Power Texas Central Company, CenterPoint Energy, City of Austin, and CPS 

29 Energy. This section summarizes each line and discusses vegetative maintenance procedures. 

30 Below, the common name for each line appears first, followed by its Electric Reliability Council 

31 of Texas (ERCOT) name in parentheses. The discussion of the power transmission system is 

32 adapted from the ER (STPNOC 2010b), the COL application (STPNOC 2010d), STPNOC’s 

33 October 2011 response to requests for additional information (STPNOC 2011f), or information 

34 gathered at NRC’s July 2011 environmental site audit.

35 2.1.5.1 Transmission Line Descriptions

36 Velasco Line (DOW 18 and DOW 27). The Velasco Line is a 45-mi (72-km)–long, double-circuit 

37 line that extends east from the STP site to the Velasco substation in Brazoria County. Its 

38 corridor is 100 ft (30 m) wide. CenterPoint Energy owns and operates this line.

39 Blessing Line (Blessing 44). The Blessing line extends west and then north from the STP site 

40 for 15 mi (24 km) to its termination point at the Blessing substation in Matagorda County. Its 

41 corridor is 100 ft (30 m) wide. American Electric Power Texas Central Company owns and 

42 operates this line.

43 Hillje Line (Hillje 64). The Hillje line extends 20 mi (32 km) northwest from the STP site to the 

44 Hillje substation in Wharton County. Its corridor is 400 ft (120 m) wide and is shared with the 
Affected Environment

2-7 

1 remaining lines discussed in this section. For simplification, this corridor will be referred to as 

2 the Hillje corridor in this section. CenterPoint Energy owns and operates the Hillje Line.

3 Hillje W.A. Parrish Loop (WAP 39). The Hillje W.A. Parrish Loop is one of two 20-mi (32-km) 

4 connector lines that join the STP site to a pre-existing (and out of scope) transmission line, the 

5 W.A. Parrish-to-Lon Hill Line. The Hillje W.A. Parrish Loop travels along the Hillje corridor. 

6 CenterPoint Energy owns and operates this line.

7 Hillje Lon Hill Loop (White Point 39). The Hillje Lon Hill Loop is the second of two 20-mi (32-km) 

8 connector lines that join the STP site to a pre-existing (and out of scope) transmission line, the 

9 W.A. Parrish-to-Lon Hill Line. The line travels along the Hillje corridor, and CenterPoint Energy 

10 owns and operates this line.

11 Holman Line (Hillje 44). The Holman Line travels through the Hillje corridor and then extends 

12 northwest for an additional 75 mi (121 km) to the Holman substation in Fayette County. The 

13 total length of the line is 95 mi (153 km). Beyond the Hillje corridor, the corridor is 100 ft (30 m)

14 wide. CenterPoint Energy owns and operates the portion of the line within the Hillje corridor, 

15 and the City of Austin owns and operates the remaining length of the line.

16 Skyline Line (Elm Creek 27). The Skyline Line travels through the Hillje corridor, extends west 

17 an additional 119 mi (192 km) to the Elm Creek substation in Guadalupe County, and then 

18 extends an additional 29 mi (47 km) to the Skyline substation in Bexar County. The total length 

19 of the line is 168 mi (271 km). Beyond the Hillje corridor, this line’s corridor is 100 ft (30 m)

20 wide. CPS Energy owns and operates the full length of this line.

21 Hill Country Line (Elm Creek 18). The Hill Country line follows the same corridor path as the 

22 Skyline Line. However, the Hill County line extends an additional 12 mi (19 km) from the 

23 Skyline substation (where the Skyline Line terminates) to the Hill Country Substation in Bexar 

24 County. The total length of this line is 180 mi (290 km).

25 White Point Loop (White Point 39). The White Point Loop is a connector line that joins the STP 

26 site to the Lon Hill Line. This line is 10 mi (16 km) long and travels along a 100-ft (30-m) wide 

27 corridor. American Electric Power Texas Central Company owns and operates this line.

28 2.1.5.2 Transmission Line Maintenance

29 American Electric Power Texas Central 

30 Company, CenterPoint Energy, City of Austin, 

31 and CPS Energy use an integrated vegetative 

32 management program that combines manual, 

33 mechanical, biological, and chemical control 

34 techniques to maintain proper clearance from 

35 transmission lines and structures. The degree 

36 and type of clearance varies by line voltage and the type, growth rate, and branching 

37 characteristics of trees and vegetation. The majority of the in-scope transmission lines traverse 

38 agricultural land and grasslands. Therefore, maintenance activities are minimal. Those areas 

39 that are not already cultivated or developed in some other way are maintained to promote 

40 herbaceous vegetation, which includes shrubs, bushes, and other low-growing groundcover.

41 2.1.6 Cooling and Auxiliary Water Systems

42 STP uses a cooling pond-based heat-dissipation system that withdraws and discharges cooling 

43 water to the MCR. STPNOC intermittently withdraws and discharges makeup water from the 

44 lower Colorado River to raise the water level and maintain water quality within the MCR. Unless 

A transmission line right-of-way (ROW) is a strip 

of land used to construct, operate, maintain, and 

repair transmission line facilities. The 

transmission line is usually centered in the ROW. 

The width of a ROW depends on the voltage of 

the line and the height of the structures. ROWs 

must typically be clear of tall-growing trees and 

structures that could interfere with a powerline.
Affected Environment 

2-8 

1 otherwise cited, the NRC staff drew information about STPNOC’s cooling and auxiliary water 

2 systems from the TPDES Permit (TCEQ 2005) and the applicant’s ER (STPNOC 2010b).

3 Circulating Water System. Water is intermittently drawn from the lower Colorado River through 

4 the Reservoir Makeup Pumping Facility (RMPF) to the MCR. The RMPF is located on the west 

5 bank of the lower Colorado River and consists of four makeup pumps with a total current 

6 capacity of approximately 269,000 gallons per minute (gpm) (600 cubic feet per second (cfs) or 

17 m3 7 /s). STPNOC intermittently draws water from the Colorado River to replace water lost in 

8 the MCR due to evaporation and seepage. This is depending on weather (patterns of rainfall in 

9 the river basin), water quality conditions in the MCR, Colorado River flows, operational 

10 considerations, and TPDES restrictions.

11 The RMPF withdraws water through a 406-ft (124-m) long intake structure located parallel to the 

12 shoreline. Water flows through a coarse trash rack with 4-in. (10-cm) openings and into 

13 traveling water screens (STPNOC 2010d). Each traveling screen is 10-ft (3-m) wide and has a 

14 mesh size of 3/8 in. (9.5 mm) (STPNOC 2010d, 2010e). A handling and bypass system on the 

15 traveling screens collects fish caught on the screens and returns them via a sluice downstream 

16 to the river (STPNOC 2010d). Water that passes through the traveling screens goes into a 

17 siltation basin, across a sharp-crested weir, and into the pumping station. The water is then 

18 pumped into the northeast corner of the MCR through two buried 108-in. (274-cm) diameter 

19 pipelines.

20 The MCR is a 7,000-ac (2,833-ha) engineered impoundment enclosed by a 12.4-mi (20-km) 

21 embankment that consists of a clay fill and is lined with a “soil-cement” to prevent erosion

22 (located adjacent to and south of STP, Units 1 and 2; see Figure 2–1). At the maximum normal 

23 operating pool of 49 ft (15 m) above mean sea level (MSL), the reservoir contains approximately 

202,700 ac-ft (250 million m3 24 ) of water. The normal operating level is 47 ft (14.3 m) above MSL 

25 due to a procedural limit for a two-unit operation.

26 Water flows from the MCR to the main condensers as water is suctioned by four circulating 

27 water pumps located within the cooling water intake structure (CWIS). Water then passes to a 

28 common distribution header for the condensers for both units. In the condenser, the circulating 

29 water absorbs waste heat. Heated water is discharged to the MCR through a discharge 

structure. Each unit circulates 906,957 gpm (3,433 cfs or 97.2 m3 30 /s) for circulating water flow 

31 (STPNOC 2009a).

32 Dikes within the MCR slow the flow of cooling water from the circulating water system discharge 

33 structure to the CWIS. As the heated water circulates in the MCR, the heat is gradually 

34 dissipated to the environment through evaporation, conduction, and long-wave radiative cooling.

35 To maintain water chemistry and quality within the MCR, STPNOC discharges water from the 

36 MCR to the Colorado River. Discharge from the MCR enters the Colorado River along the west 

37 bank through a series of seven 36-in. (91-cm) pipes directed downstream at an angle of 

38 45 degrees from the shore. The discharge structures are 2 mi (3 km) downstream of the RMPF.

39 The pipes entering the river are spaced 250 ft (76 m) apart. STPNOC’s TPDES permit limits the 

daily discharge to 144 mgd (5.45 million m3

/d)

 40 and shall not exceed 12.5 percent of the flow of 

41 the Colorado River at the discharge point (TCEQ 2005). The TPDES permit also prohibits 

42 STPNOC from discharging wastewater when the Colorado River adjacent to the plant is less 

than 800 cfs (22.7 m3 43 /s). The Texas Administrative Code limits the daily average temperature 

44 to 95 °F (35 °C) and daily maximum temperature to 97 °F (36 °C) (STPNOC 2010b). STPNOC 

45 has discharged to the Colorado River once during the operation of STP in 1997 as part of a 

46 system test (STPNOC 2010b).
Affected Environment

2-9 

1 Auxiliary Cooling Water and Essential Cooling Water Systems. The MCR supplies the auxiliary 

2 cooling water system with cooling water for nonsafety-related systems. Water travels from the 

3 MCR to the auxiliary cooling water system through a separate bay in the MCR intake structure 

4 and then heated water discharges to the MCR. The design flow rate is 23,600 gpm (52.6 cfs or 

1.5 m3 5 /s). 

6 The essential cooling pond (ECP) supplies the essential cooling water system with cooling 

7 water for safety-related systems. The ECP is approximately 46 ac (19 ha). Three groundwater 

8 wells are the primary makeup to the ECP. The design flowrate is 19,280 gpm (43 cfs or 

1.2 m3 9 /s). After going through the essential cooling water system, the water is discharged to the 

10 ECP, which is the ultimate heat sink. STPNOC discharges water from the ECP to the MCR to 

11 maintain water chemistry.

12 2.1.7 Facility Water Use and Quality

13 STP, Units 1 and 2, use water systems that include the circulating water systems (CWSs), the 

14 freshwater and service water systems, the potable and sanitary water systems, and the auxiliary 

15 cooling water and essential cooling water systems (ECWSs) (see Section 2.1.6). STP uses a 

16 cooling pond to reject waste heat from normal operations to the atmosphere. The 7,000-ac 

17 (2,830-ha) MCR is located adjacent to and south of STP, Units 1 and 2 (see Figure 2–1). The 

18 MCR has a spillway near its southeast corner for the discharge of excess water from the MCR 

19 to the Colorado River during heavy precipitation events. The MCR also has a buried discharge 

20 pipe that runs for 1.1 mi (1.8 km), adjacent to the spillway discharge channel, which ends at a 

21 seven-port outfall. This is STPNOC’s combined outfall (001) under STPNOC’s TPDES permit. 

22 This pipe allows for the discharge of blowdown (i.e., water high in dissolved solids) from the 

23 MCR to the Colorado River. The MCR spillway is seldom used, and the blowdown pipeline has 

24 only been used as part of a test in 1997. The MCR has a normal maximum operating level of 

25 49 ft (15 m) above MSL for a four-unit operation, but it currently operates under a procedural 

26 limit of 47 ft (14 m) above MSL for a two-unit operation (STPNOC 2010b).

27 The RMPF diverts water from the Colorado River to the MCR to replenish water lost due to 

28 evaporation and seepage. The RMPF is located on the Colorado River to the east of the 

29 operating units and delivers water to the MCR through two buried 108-in. (274-cm) diameter 

30 makeup water lines. As currently configured (e.g., screens and pumps), the intake structure has 

a pumping capacity of 269,000 gpm (600 cfs or 17 m3 31 /s).

32 In addition to the water supply from the Colorado River, STPNOC maintains five groundwater 

33 supply wells at STP as the source for the freshwater and service water systems (including the 

34 demineralizer system), potable and sanitary water systems, the firewater storage tanks, the 

35 Nuclear Support Center cooling tower, and fire protection for the Nuclear Training Facility. 

36 Three of the five onsite wells provide water to the service system and the fire water storage 

37 tanks, and one well each supports the Nuclear Support Center cooling tower and the Nuclear 

38 Training Facility (STPNOC 2010b).

39 The auxiliary cooling water system draws cooling water for nonsafety-related systems from the 

40 MCR. Heated water from this system returns to the MCR. The design flow rate of this system 

is 23,600 gpm (53 cfs or 1.5 m3 41 /s). The essential cooling water system (ECWS) draws cooling 

42 water for safety-related systems from the ECP. Heated water from this system returns to the 

ECP. The design flow rate for this system is 19,280 gpm (43 cfs or 1.2 m3 43 /s). Makeup to the 

44 ECP is from one of the three groundwater wells providing service water and fire water storage. 

45 The ECP also is equipped with the capability to discharge blowdown to the MCR to maintain 

46 water chemistry (STPNOC 2010b).
Affected Environment 

2-10

1 A description of surface water resources at STP and vicinity is provided in Section 2.2.4, and a 

2 description of the groundwater resources is presented in Section 2.2.5. The following sections 

3 further describe the water use from these resources.
Affected Environment

2-11

1 Figure 2–1. Surface Water Bodies and Groundwater Wells in 

2 Vicinity of STP (STPNOC 2011b) 
Affected Environment 

2-12

1 2.1.7.1 Surface Water Use 

2 Feedwater for the STP, Units 1 and 2, CWS is supplied by the MCR, with makeup water for the 

3 MCR diverted from the lower Colorado River using the RMPF, as previously described. The 

4 RMPF was designed to accommodate operations of four units at the STP site. Currently, the 

RMPF has 269,000 gpm (600 cfs or 17 m3 5 /s) of installed pumping capacity to support the 

6 operation of Units 1 and 2. The MCR also supplies water to the auxiliary cooling water systems, 

7 which provide cooling for nonsafety-related systems (STPNOC 2010b).

8 Through a Certificate of Adjudication issued by the Texas Water Commission, STPNOC has 

9 priority water rights through the lower Colorado River Authority to use 102,000 ac-ft/yr 

(126 million m3 10 /yr) of water from the lower Colorado River. STP can withdraw river water up to 

a maximum rate of 540,000 gpm (1,200 cfs or 34.4 m3 11 /s). However, STPNOC’s diversions are 

12 limited to 55 percent of the flow of the lower Colorado River that is in excess of a 300-cfs 

(8.5-m3 13 /s) base flow at the diversion point. This is intended to protect freshwater inflows to 

14 Matagorda Bay during low flow conditions. The Certificate of Adjudication also provides rights 

for an additional 20,000 ac-ft (24.7 million m3 15 ) of water for operation of STP, Units 1 and 2. 

16 Should sufficient water not be available from the lower Colorado River to maintain the MCR at 

17 or above an elevation of 27 ft (8.2 m) above MSL, stored water would be released by the lower 

18 Colorado River Authority from sources (i.e., Highland Lakes) upstream of Bay City Dam 

19 (STPNOC 2009b, 2010b).

To operate STP, Units 1 and 2, STPNOC diverted an average of 37,850 ac-ft (46.7 million m3 20 ) 

21 of water per year from the Colorado River between 2003 and 2010. STPNOC’s diversion during 

22 this period ranged from zero in 2003, due to low flow restrictions, to 72,464 ac-ft 

(89.4 million m3 23 ) during 2009 (STPNOC 2010b, 2011b).

24 2.1.7.2 Groundwater Use

25 Groundwater is withdrawn at STP via five onsite wells to supply the freshwater and service 

26 water systems, potable and sanitary water systems, and fire protection storage tanks and to 

27 provide makeup water for the ECWS (see Section 2.1.7).

28 The five water-supply wells (see Figure 2–1) were installed during construction of STP, Units 1 

29 and 2, and all are completed in the Deep Chicot Aquifer, as further described in Section 2.2.5. 

30 These wells range in depth below ground surface (BGS) from 600 to 700 ft (183 to 213 m) and 

31 have design capacities between 200 and 500 gpm (760 to 1,890 L/min) (NRC 2011b; 

32 STPNOC 2010b). STP holds a permit from the Coastal Plains Groundwater Conservation 

District to withdraw 9,000 ac-ft (11.1 million m3 33 ) of groundwater over an approximately 3-year 

34 permit period (CPGCD 2011). This is a pumping rate of approximately 1,860 gpm (7,040 L/min) 

or 3,000 ac-ft/yr (3.7 million m3 35 /yr). Based on data from 2001 through 2010, STPNOC’s total 

36 annual groundwater production ranged from 682 to 863 gpm (2,580 to 3,270 L/min) or 1,100 to 

1,392 ac-ft/yr (1.4 to 1.7 million m3 37 /yr) and averaged 768 gpm (2,910 L/min) or 1,239 ac-ft/yr 

(1.5 million m3 38 /yr) (STPNOC 2010b, 2010d, 2011b).

2.2

40 Sections 2.2.1 through 2.2.10 provide general descriptions of the environment near STP as 

41 background information. They also provide detailed descriptions, where needed, to support the 

42 analysis of potential environmental impacts of operation during the renewal term, as discussed 

43 in Sections 3 and 4.

39 Surrounding Environment
Affected Environment

2-13

1 2.2.1 Land Use

2 STP is located in Matagorda County, 8 mi (3.2 km) north-northwest of Matagorda and sits 

3 between Farm-to-Market Road (FM) 1095 to the west and the Colorado River to the east. The 

4 STP site is located on approximately 12,220 ac (4,945 ha). The operations area, consisting of 

5 the reactor buildings, support facilities, and transmission ROWs occupies approximately 65 ac

6 (26 ha); the ECP, approximately 46 ac (19 ha); and the MCR, an additional 7,000 ac (2,833 ha). 

7 Another 1,700 ac (688 ha) is natural low land habitat. The rest of the site is mostly undeveloped 

8 land; a portion of which, east of the MCR, is leased for cattle grazing (STPNOC 2010b).

9 Onsite facilities include the two reactor and steam generator containment buildings, various 

10 buildings auxiliary to the reactors such as warehouses, a chemical storage building, switchyard, 

11 fuel handling buildings, radioactive waste building, training center, outdoor firing range, 

12 administrative buildings, and miscellaneous supporting buildings (STPNOC 2010b).

13 Nearby communities include Matagorda, approximately 8 mi (13 km) north-northwest; Palacios, 

14 11 mi (18 km) north-northwest; and Bay City, 13 mi (21 km) southeast. The western bank of the 

15 Colorado River forms the eastern STP property boundary. A 13-acre (5-ha) park, developed by 

16 the lower Colorado River Authority (LCRA) and operated by Matagorda County, is located on 

17 FM 521 on the west side of the Colorado River. The Port of Bay City terminal is located 

18 approximately 5 mi (8 km) north-northeast of the STP site.

19 2.2.2 Air Quality and Meteorology

20 STP is located in Matagorda County, a coastal county located on the Gulf of Mexico in the 

21 southeastern portion of Texas. There are 10 climatic divisions of Texas, with Matagorda County 

22 falling into the Gulf Coastal Plain, primarily a combination of prairies and marshes. The climate 

23 for this region is classified as maritime subtropical, which is marked by relatively short, mild 

24 winters; long, hot summers; and mild springs and falls. The Azores high-pressure system is the 

25 source of maritime tropical air masses much of the year. During the winter months, occasional 

26 cold continental air masses displace the maritime air. The STP site is flat with no topographic 

27 features that would cause the local climate to deviate significantly from the regional climate. 

28 While tornadoes and floods are the primary weather hazards in the rest of the State, the Gulf 

29 Coastal Plain is most vulnerable to hurricanes.

30 The closest first-order National Weather Service (NWS) station representative of the STP site is 

31 Victoria, Texas, located about 53 mi (85.3 km) to the west of the site. The NWS station at 

32 Corpus Christi, Texas, about 100 mi (161.0 km) to the southwest, is also representative of the 

33 site due to its proximity to the coast. Summer climate extends from May through September, 

34 with the highest average temperatures occurring during July and August, which are 83.8 °F 

35 (28.8 °C) and 83.7 °F (28.7 °C), respectively. The winter climate extends from December 

36 through February, with the coldest weather occurring in January at 55.7 °F (13.2 °C) on 

37 average. The fall climate occurs in October and November, with average temperatures of 

38 72.6 °F (22.6 °C) and 64.6 °F (18.1 °C) respectively. The spring climate at STP extends from 

39 March to April, with average temperatures of 65.4 °F (18.6 °C) and 70.2 °F (21.2 °C), 

40 respectively. The Gulf of Mexico can modify outbreaks of polar air masses such that 

41 temperatures below 32 °F (0 °C) may occur, on average, less than four times per year.

42 2.2.2.1 Air Quality

43 Matagorda County is within the Metropolitan Houston–Galveston Intrastate Air Quality Control 

44 Region (AQCR). Other counties in the region include Austin, Brazoria, Chambers, Colorado, 

45 Fort Bend, Galveston, Harris, Liberty, Montgomery, Walker, Waller, and Wharton Counties

46 (40 CFR 81.38).
Affected Environment 

2-14

1 The EPA regulates six criteria pollutants under the National Ambient Air Quality Standards 

2 (NAAQS)—carbon monoxide, lead, nitrogen dioxide, ozone, sulfur dioxide, and particulate 

3 matter. Matagorda County is designated as unclassified or in attainment for all NAAQS criteria 

4 pollutants. However, the counties of Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, 

5 Montgomery, and Waller are classified as “[N]onattainment[/]Severe” (40 CFR 81.344) for the 

6 8-hour ozone standard. These counties are located northeast or north-northeast of Matagorda 

7 County, with the closest being Brazoria County, located approximately 21 mi northeast of the 

8 STP site. All other counties in this AQCR are designated as unclassified or in attainment with 

9 respect to the NAAQS criteria pollutants.

10 STP has many stationary emission sources, such as standby emergency diesel generators, an 

11 auxiliary boiler to furnish steam for start-up when the nuclear steam supply is unavailable, and 

12 several petroleum fuel storage tanks. STP submits a report of air emissions to TCEQ annually. 

13 Actual total emissions from all sources at STP from 2004 to 2010 were 62.86 tons per year 

14 (tpy), 58.15 tpy, 56.24 tpy, 47.07 tpy, 60.68 tpy, 59.97 tpy, and 65.37 tpy, respectively. With the 

15 exception of volatile organic compounds (VOC), the highest emissions were reported in 2004, 

16 with 1.11 tpy of particulate matter, 12.41 tpy of carbon monoxide, 46.62 tpy of oxides of 

17 nitrogen, and 0.78 tons per year of sulfur dioxide. The highest VOC emissions were reported in 

18 2009 and were 2.07 tpy. There are no plans for refurbishment of structures or components at 

19 the STP site for license renewal. Therefore, there are no changes to expected air emissions 

20 associated with license renewal (STPNOC 2010b, 2012a) 

21 Mandatory Class I Federal Areas, where visibility is an important value, are listed in 

22 40 CFR Part 81, Subpart D. There are no mandatory Class I Federal areas within 50 mi

23 (81 km) of the STP site. The closest Class I area to STP is the Big Bend National Park located 

24 in west Texas, which is over 500 mi (805 km) west of the STP site. Due to the significant 

25 distance from the site and prevailing wind direction, no adverse impacts on Class I areas are 

26 anticipated from STP operation. Furthermore, there are no expected additional air emissions 

27 associated with license renewal (no new emission sources). 

28 STP has had a Meteorological Monitoring Program on site since July 1973. The initial 

29 measurements were to provide the onsite meteorological information required for licensing of 

30 STP, Units 1 and 2. Measurements have continued in support of the existing STP, Units 1 

31 and 2, operations. The primary meteorological tower is approximately 1.5 mi (2.4 km) to the 

32 east of STP, Units 1 and 2. Its instruments include wind speed and direction and temperature 

33 sensors at 10 m (33 ft) and 60 m (197 ft) above ground, dew point temperature at 10 m (33 ft) 

34 above ground, and precipitation and solar radiation near ground level. A 10 m (33 ft) backup 

35 meteorological tower is located about 0.4 mi (0.6 km) south of the primary tower. 

36 Instrumentation on the backup tower consists of wind speed and direction and temperature at 

37 10 m (33 ft). 

38 2.2.2.2 Meteorology

39 Wind at the STP site is consistent with the dominant influence of the Azores high-pressure 

40 system and the coastal location of the site. Seasonal variation of the prevailing directions 

41 shows a predominance of southeasterly winds except in January, July, and August, when south 

42 winds prevail, and November and December, when northerly winds prevail. The coastal 

43 location of the site leads to typical onshore (southeast) winds during the day and offshore winds 

44 at night.

45 Precipitation at the STP site ranges from about 2 in. (5.1 cm) per month in February, peaking to 

46 about 4 to 5 in. (10.2 to 12.7 cm) per month in May and June and again in September and 

47 October. Snow occurs during more than 50 percent of the winters, but snowfall is generally 

48 limited to trace amounts. STP can experience severe weather in the form of thunderstorms, 
Affected Environment

2-15

1 tornadoes, and tropical storms. Thunderstorms are the most frequent severe weather events. 

2 They occur on an average of about 55 days per year at the Victoria NWS station and about 

3 31 days per year at Corpus Christi NWS station. The majority of the thunderstorms occur from 

4 the months of May through September. It is likely that the frequency of thunderstorms at the 

5 STP site is closer to that of the Corpus Christi NWS station than the Victoria NWS station due to 

6 Corpus Christi’s proximity to the coastline. Tropical cyclones, including hurricanes and tropical 

7 storms, pass near the STP site an average of about once every other year, and an average of 

8 about two to three hurricanes pass near the site every 10 years. Nine hurricanes have made 

9 landfall between Corpus Christi and Galveston since 1950, the most recent being hurricanes 

10 Humberto in 2007 and Ike in 2008. Tornadoes are the least frequent of these extreme weather 

11 events.

12 2.2.3 Geologic Environment 

13 This section describes the current geologic environment of the STP site and vicinity including 

14 landforms, geology, soils, and seismic setting.

15 Physiography. STP is located within the Coastal Prairies portion of the Texas Gulf Coastal 

16 Plains physiographic province. The Coastal Prairies subprovince is a broad band paralleling the 

17 Texas Gulf coasts (BEG 1996). The topography in the immediate vicinity of the site is 

18 characterized by a relatively flat coastal plain with elevations generally ranging from 20 to 30 ft

19 (6 to 9 m) above MSL, with an average elevation of 23 ft (7 m) above MSL across STP 

20 (NRC 2011b; STPNOC 2009a).

21 One unique topographic feature in the region is the presence of “pimple mounds,” which can be 

22 seen throughout the Texas coastal area. These round or elliptical features are typically about 

23 2 ft (0.6 m) high and 50 ft (15 m) or less in diameter. They are most frequently associated with 

24 low-lying, poorly drained areas or bodies of water. These mounds are not restricted to a 

25 specific soil series or type, but they occur on many different types of soils with various moisture 

26 contents and have no connection to deeper sediments. Although many theories have been 

27 proposed for their origin, their structure indicates that they result from normal sedimentary 

28 deposition in calm water environments (STPNOC 2009a).

29 Geology. STP sits on the Beaumont depositional plain, one of several such surfaces trending 

30 northeast-southwest along the Texas Gulf coasts that formed during the Pleistocene Age

31 (i.e., between approximately 12,000 and 2.6 million years ago), due to changes in sea level 

32 associated with coastal subsidence and inland geologic uplift. This plain reflects the uppermost 

33 surface of a sequence of Quaternary Age sediments approximately 3,000 ft (910 m) thick that 

34 were deposited by ancient river systems and in deltas. Test borings indicate such sediments 

35 are present to a depth of at least 2,619 ft (798 m) beneath the site with ages of no more than 

36 700,000 years. Nevertheless, there has been little modification of this depositional plain since 

37 the uppermost Beaumont Formation was deposited approximately 70,000 years ago. Today, 

38 this plain is crossed by the very shallow but relatively wide (4 mi or 6.6 km) Colorado River 

39 valley, which the river has meandered back and forth across over time (STPNOC 2009a).

40 The uppermost geologic unit across and underlying the STP site is the Beaumont Formation, 

41 which is estimated to extend to a depth of 1,400 ft (430 m). The top 125 ft (38 m) of this unit is 

42 comprised of silt, sandy silt, and fine- to medium-grained sand, interbedded with clay. Clay 

43 predominates below 125 ft (38 m). Lenses of moderately dense to very dense reddish-brown to 

44 gray silty sand are found in the clay layers. Along the eastern boundary of the site, Holocene 

45 (recent) Age alluvial age sediments, which range up to 50 ft (15 m) thick, overlie the Beaumont 

46 Formation. In addition, Holocene sand, silt, and clay deposits are found in the Colorado River 

47 meander belt and floodplain east of the plant site. While finer sediments (silt, clay) were 
Affected Environment 

2-16

1 generally deposited in low areas, sand was deposited as point bars or sheet deposits during 

2 flood stages (STPNOC 2009a).

3 No geologic (tectonic) faults capable of producing earthquakes have been identified in the STP 

4 region, and no unstable subsurface materials or conditions (e.g., salt domes) have been 

5 identified at the plant site. The closest tectonic faults are located approximately 85 mi (140 km) 

6 northwest of the STP site in association with the Ouachita geologic province. Many “growth” 

7 faults have been mapped at depth in the STP site area and extensively studied through 

8 geophysical data. Common across the Texas Gulf coasts, these features are thought to arise 

9 from gravity-related processes associated with the consolidation, slumping, and creeping of 

10 sediments during and after being deposited. At STP, nearly all of these features are confined to 

11 strata at depths of at least 5,000 ft (1,520 m) BGS in Oligocene age strata comprised of the 

12 massive marine shales of the Anahuac Formation. This indicates that the growth faults are at 

13 least as old as the strata in which they are found (i.e., as old as 26 million years) and further 

14 indicates that they are depositional and not tectonic in nature (STPNOC 2009a).

15 Soils. Soil unit mapping by the National Resources Conservation Service (NRCS) identifies the 

16 natural soils across the STP main plant complex as Laewest clay, 0 to 1 percent slopes, with 

17 areas of Dacosta sandy clay loam, 0 to 1 percent slopes, to the east and north of the main plant 

18 complex. These units are deep (greater than 80 in. (200 cm)), moderately well drained soils, 

19 which developed from clayed clayey fluviomarine deposits. Both soils are prime farmland where 

20 otherwise not committed to developed uses (7 CFR 675.5). The soils have some limitations for 

21 site development due to shrink-swell from high expansive clay content and a slight erosion 

22 hazard (NRCS 2011).

23 Overall, the plant area excavation consisted of a large open-cut excavation covering the 

24 footprint of both units to a depth of approximately 40 ft (12 m) BGS. Excavations for the two 

25 reactor containment buildings (RCBs) extended deeper to nearly 70 ft (21 ft) BGS. These 

26 excavations penetrated the shallow aquifer zone (see Section 2.2.5 for details), requiring 

27 groundwater dewatering during construction. The excavated area was backfilled to the 

28 foundation elevations and to within 18 in. (46 cm) of surface grade with clean, well-graded, 

29 medium-to-coarse sand. The total amount of Category I structural backfill used for Units 1 

30 and 2 was approximately 1.6 million tons (1.45 million MT) (STPNOC 2009a).

31 Seismic Setting. The central Texas Gulf coast is a region of very low historical seismicity and 

32 very low seismic risk (USGS 2011a). No earthquakes have been recorded within a radius of 

33 62 mi (100 km) of STP. Within a radius of 124 mi (200 km), only seven earthquakes have been 

34 recorded. The closest event was a magnitude 2.7 event with an epicenter 70 mi (113 km) 

35 northwest of STP (USGS 2011b).

36 Site and regional studies across the Gulf coasts have concluded that the geologic strata in 

37 which the previously described growth faults are known to occur are not capable of storing 

38 strain energy sufficient to produce earthquakes larger than about magnitude 4.0 or shaking 

39 greater than Modified Mercalli Intensity (MMI) IV or both. Historically, earthquake activity in the 

40 region attributed to growth faulting has been of magnitude 1.5 or less (microseismic). Further, 

41 as reported in the applicant’s updated final safety analysis report (FSAR), no earthquakes are 

42 known to have occurred or been felt at the STP site. Nevertheless, larger earthquakes have 

43 occurred along the Gulf coasts. The largest historical earthquake in the Gulf coasts region 

44 occurred in October 1930 near Donaldsonville, Louisiana, approximately 320 mi (515 km) 

45 east-northeast of the STP site. Although not recorded on instruments, its epicenter and effects 

46 were based on historical accounts. It is believed to have occurred in the upper basement rock 

47 rather than in the overlying strata and produced shaking of MMI of V to VI at its epicenter 

48 (STPNOC 2009a). USGS information provides an estimated magnitude of 4.2 with a 
Affected Environment

2-17

1 conservative MMI of VI for this event (USGS 2011c). Nevertheless, the 1930 Donaldsonville 

2 earthquake was used as one of the bases to establish the safe shutdown earthquake (SSE) for 

3 STP where an earthquake producing shaking of MMI VI at the surface was assumed to occur in 

4 basement rock directly beneath the site. The maximum vibratory (peak) ground acceleration 

5 (PGA) associated with an MMI VI earthquake is about 0.07 g (i.e., force of acceleration relative 

6 to that of Earth’s gravity, “g”). Nonetheless, because 0.07 g is below the minimum PGA value in

7 10 CFR Part 100, Appendix A, 0.10 g was adopted for the SSE (STPNOC 2009a).

8 For the purposes of comparing the SSE with a more contemporary measure of predicted 

9 earthquake ground motion for the site, the NRC staff also reviewed current PGA data from the 

10 U.S. Geological Survey (USGS) National Seismic Hazard Mapping Project. The PGA value 

11 cited is based on a 2 percent probability of exceedance in 50 years. This corresponds to an 

annual frequency (chance) of occurrence of about 1 in 2,500 or 4x10-4 12 per year. For STP, the 

13 calculated PGA is approximately 0.03 g (USGS 2008).

14 2.2.4 Surface Water Resources

15 The STP site is situated on the west bank of the lower Colorado River, approximately 13 mi

16 (21 km) southwest of Bay City, Texas, and 10 mi (16 km) north of Matagorda Bay. The STP site 

17 is approximately 12,200 ac (4.940 ha) in size, the majority of which is occupied by the 7,000-ac 

18 (2,830-ha) MCR. This reservoir is formed by approximately 12.4 mi (20 km) of embankment 

19 consisting of clay fill that is constructed above natural ground elevation. The MCR also has 7 mi

20 (11 km) of internal baffles (raised berms) to enhance the circulation of cooling water 

21 (STPNOC 2010b).

22 As described in Sections 2.1.6 and 2.1.7, the MCR is part of the closed-loop cooling system for 

23 the normal operations of STP, Units 1 and 2. The CWSs of STP, Units 1 and 2, discharge 

24 heated water to the MCR, where rejected heat is dissipated mostly via evaporation. To 

25 replenish the waters lost to evaporation, the RMPF supplies makeup water from the lower

26 Colorado River. The pumps in the RMPF are operated intermittently consistent with Colorado 

27 River flow conditions, operational considerations, and permit restrictions.

28 2.2.4.1 Surface Water Hydrology

The Colorado River Basin is approximately 42,318 mi2 (109,600 km2 29 ) in area (NRC 2011b). 

30 STP is located at lower Colorado River Mile 14.6 upstream from Matagorda Bay. The river is 

31 tidally influenced in the vicinity of the STP site, and this tidal influence extends as far as 32 mi

32 (51 km) upstream from Matagorda Bay under conditions of low flow. The extent of tidal 

33 influence depends on tidal fluxes at the mouth of the river, freshwater inflow down the river, and 

34 other conditions. In addition, saltwater may move as far as 24 mi (39 km) upstream of 

35 Matagorda Bay, along the bottom of the Colorado River (STPNOC 2010b). The mean annual 

36 discharge measured at the USGS gauge near Bay City for water years 1949 through 2010 is 

2,620 cfs or 1.17 million gpm (74.1 m3 37 /s) (USGS 2011d). August is the low-flow month, and 

38 June is the high-flow month (NRC 2011b).

39 Texas experiences frequent droughts, primarily caused by the formation of a stationary 

40 high-pressure system called the Bermuda High. Multi-year droughts have occurred in the past 

41 in the Colorado River Basin; for example, annual discharges during 1951 to 1956, 1962 to 1967, 

42 1983 to 1986, and 1988 to 1991 ranged from 23 to 48 percent, 21 to 79 percent, 25 to 

43 72 percent, and 21 to 78 percent of the mean annual discharge, respectively (NRC 2011b). Of 
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the 56 years of data reported by USGS from 1949 to 2010 water years,1

3 In the Colorado River Basin, the LCRA operates six dams that impound six Highland Lakes, 

having a combined water storage capacity of 2.18 million ac-ft (2,690 million m3 4 ). The LCRA

5 operates the Colorado River and Lakes Buchanan and Travis as a single system for water 

6 supply in the lower Colorado River Basin, including for STP (see Section 2.1.7.1). Water from 

7 the lakes is released when the flow in the river is insufficient to meet downstream water rights 

8 (NRC 2011b).

1 the annual discharge 

2 was less than the mean annual discharge during 26 years. 

9 Other noteworthy surface water features at STP include Little Robbins Slough, an intermittent 

10 stream, which originates approximately 2 mi (3.2 km) northwest of the STP site; it has a 

drainage area of approximately 4 mi2 (10.4 km2 11 ). During construction for Units 1 and 2, the 

12 original course of Little Robbins Slough was relocated along the west portion of the MCR 

13 embankment. Currently, the relocated Little Robbins Slough flows south along the west MCR 

14 embankment, turns east at the southwest corner of the MCR embankment, and rejoins its 

15 original course approximately 1 mi (1.6 km) east of the southwest corner of the MCR 

16 embankment (NRC 2011b) (see Figure 2–1).

17 Kelly Lake is a 34-ac (14-ha) natural water body located north of the northeast edge of the MCR 

18 embankment and is fed by a small catchment area to its north. The ECP, which serves as the 

19 ultimate heat sink for STP, Units 1 and 2, is located east of the power block and comprises 

20 another 46 ac (19 ha) of land (NRC 2011b; STPNOC 2010b).

21 2.2.4.2 Surface Water Quality and Effluents

22 In support of maintaining the quality of waters of the State and in establishing designated uses 

23 of surface waters, TCEQ has designated the segment of the lower Colorado River 

24 (Segment 1401, Colorado River Tidal), adjacent to STP, for use in primary contact recreation 

25 and for high aquatic life use, as well as for general and fish consumption uses applicable to all 

26 surface waters (30 TAC 1-307). The numeric water quality criteria specified for the river 

27 segment include a minimum 24-hour mean dissolved oxygen at any point of 4.0 mg/L, a pH 

28 range of 6.5 to 9.0 units, an indicator bacteria count of 35 colonies per 100 milliliters (mL), and a 

29 maximum temperature of 95 °F (35 °C) (NRC 2011b; TCEQ 2011).

30 The lower Colorado River Authority has a water quality monitoring station on the lower Colorado 

31 River at Selkirk Island, located approximately 0.7 mi (1.1 km) downstream from the STPNOC’s 

32 RMPF. For the period of October 1982 through November 2008, dissolved oxygen levels 

33 ranged from 0 to 13.5 mg/L with an average of 6.5 mg/L, pH ranged from 6.6 to 9.8 units with an 

34 average of 7.9, and water temperatures ranged from 43.5 to 92.1 °F (6.4 to 33.4 °C) with an 

35 average of 72.5 °F (22.5 °C). Between 1994 and 2001, fecal coliform ranged from 0 to 

36 13,000 colonies per 100 mL, with an average of 391 colonies per 100 mL (NRC 2011b).

37 Texas’ draft 2010 Clean Water Act, Section 303(d), list of impaired waters proposes to continue 

38 the listing of the tidal lower Colorado River as impaired by bacteria; it was first listed for bacteria 

39 exceedances in 2006 (based on best available information). The other surface water bodies 

40 near the STP site—including Little Robbins Slough, West Branch of the Colorado River, and 

41 Kelly Lake—are not on the Section 303(d) list (NRC 2011b; TCEQ 2011).

42 Wastewater discharges from STP are governed by a TCEQ-issued TPDES permit. This is the 

43 Texas equivalent of a National Pollutant Discharge Elimination System permit. STPNOC’s 

 

1 For statistical calculations, the USGS does not use years during which data are incomplete. For calculating the annual statistics 

for Colorado River stream flow at Bay City, the USGS did not use water years 1996 through 2000 and 2009.
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1 current TPDES permit (No. WQ0001908000) was issued by TCEQ with an effective date of 

2 July 27, 2005; the permit expired on December 1, 2009. However, STPNOC submitted a permit 

3 renewal application to the State on June 2, 2009, which the TCEQ accepted as administratively 

4 complete on July 13, 2009. Consequently, STPNOC’s TPDES permit remains valid and in 

5 effect (i.e., administratively continued) until a new permit is issued (STPNOC 2011d; 

6 TCEQ 2009). Regarding Water Quality Certification requirements under Section 401 of the 

7 Clean Water Act, TCEQ issued a waiver to STPNOC with respect to renewal of STPNOC’s 

8 NRC operating licenses as STP discharges are otherwise subject to TPDES permitting 

9 requirements (STPNOC 2012b). 

10 The site’s TPDES permit sets effluent limitations for site discharges to the Colorado River from 

11 the MCR via outfall 001 including comingled recirculated cooling water, MCR blowdown, 

12 stormwater, and makeup water from Colorado River. This also includes limits on several 

13 “previously monitored” effluent streams or internal outfalls that discharge to the MCR and 

14 identified as outfall numbers 101, 201, 401, 501, and 601. Additionally, the permit covers 

15 discharges from other miscellaneous sources such as MCR relief wells, MCR spillway gate 

16 leakage, and from groundwater monitoring wells that may flow to the Colorado River, to the 

17 West Branch of the Colorado River, to Little Robbins Slough, and to the East Fork of Little 

18 Robbins Slough, as appropriate (TCEQ 2005).

19 In addition to limitations on specific pollutants and on discharge temperature, the current 

20 TPDES permit requires that the discharge from outfall 001 not exceed 12.5 percent of the flow 

21 of the Colorado River at the discharge point and prohibits discharges from outfall 001 when river 

flow adjacent to the plant is less than 800 cfs (23 m3 22 /s). It also imposes an average daily 

discharge flow limit of 144 million gallons per day (mgd) (585,000 m3 23 /day) (TCEQ 2005). As 

24 noted above (and previously in Section 2.1.7), the MCR is equipped with a blowdown discharge 

25 pipeline to reduce the level of dissolved solids in the circulating water. While this blowdown 

26 pipeline has only been used once before, it may be necessary to discharge from the MCR via 

27 outfall 001 in the future to maintain proper circulating water chemistry (STPNOC 2010b).

28 The NRC staff’s review of the last 3 years of TPDES discharge monitoring reports submitted by 

29 STPNOC to the TCEQ revealed no exceedances of TPDES effluent limitations. Further, 

30 STPNOC has not received any Notices of Violation, nonconformance notifications, or related 

31 infractions associated with the site’s TDPES permit or related to other water quality matters 

32 within the past 5 years (STPNOC 2011e).

33 2.2.5 Groundwater Resources

34 2.2.5.1 Site Description and Hydrogeology

35 Underlying the STP site is a wedge of southeasterly dipping sedimentary deposits. Three 

36 depositional environments are evident—continental (alluvial plain), transitional (delta, lagoon, 

37 beach), and marine (continental shelf). As further discussed in Section 2.2.3, oscillations of the 

38 ancient shoreline and other processes have resulted in overlapping mixtures of sediments. 

39 Numerous local aquifers exist in the thick sequences of alternating and interfingering beds of 

40 clay, silt, sand, and gravel, which yield groundwater ranging in quality from fresh to saline

41 (Ryder 1996; STPNOC 2010d).

42 The USGS identified the aquifers underlying the STP site as the Texas coastal lowlands aquifer 

43 system, and it divides the aquifer system into hydrogeologic units or permeable zones A 

44 through E (Ryder and Ardis 2002). Within the State of Texas, both the Texas Water 

45 Development Board and the LCRA refer to the aquifer system as both the Gulf Coast Aquifer 

46 system and the coastal lowlands aquifer system, and they use hydrogeologic unit names rather 
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1 than letters to describe the aquifer system (TWDB 2006, 2007; Young et al. 2007). Common 

2 hydrogeologic unit names, from shallow to deep, are as follows (STPNOC 2010d):

3 • Chicot Aquifer, 

4 • Evangeline Aquifer, 

5 • Burkeville Confining Unit, 

6 • Jasper Aquifer, 

7 • Catahoula Confining Unit, and

8 • Vicksburg–Jackson Confining Unit.

9 This SEIS adopts the naming convention used by the State of Texas. The aquifers underlying 

10 the site are located in the Holocene-aged alluvium and the Pleistocene-aged Beaumont, 

11 Montgomery, Bentley Formations, and Willis Sands that make up the Chicot Aquifer 

12 (NRC 2011b). In descending order from the land surface, the aquifers of interest are the Upper 

13 Shallow Chicot Aquifer, the Lower Shallow Chicot Aquifer, and the Deep Chicot Aquifer. The 

14 Upper and Lower Shallow Chicot aquifers exhibit semi-confined behavior with some movement 

15 of groundwater between them. Local to STP, Units 1 and 2, this communication between the 

16 upper and lower zones is also a result of the excavation of the semi-confining material 

17 separating the two zones during construction of the units. The top of the Upper Shallow Chicot 

18 Aquifer is designated at approximately 15 to 30 ft (4.6 to 9.1 m) BGS, and its base is at about 

19 50 ft (15 m) BGS. The Lower Shallow Chicot Aquifer lies between 50 and 150 ft (15 to 46 m)

20 BGS (NRC 2011b). The depth to groundwater within this shallow aquifer system lies at 

21 approximately 15 to 20 ft (4.6 to 6.1 m) BGS (MACTEC 2009). The upper surface of the Deep 

22 Chicot Aquifer is between 250 and 300 ft (76 to 91 m) BGS. The approximate depth where 

23 groundwater has a total dissolved solids (TDS) concentration of more than 10,000 mg/L defines 

24 the base of the Deep Chicot Aquifer. Beneath the STP site, the Chicot Aquifer thickness is 

25 somewhat greater than 1,000 ft (305 m). The Upper Shallow Chicot Aquifer exhibits a 

26 somewhat higher potentiometric head than the Lower Shallow Chicot Aquifer, and groundwater 

27 moves from the Upper into the Lower Shallow Chicot Aquifer through the confining zone that 

28 separates them. The Deep Chicot Aquifer is separated from the Lower Chicot Aquifer by 100 to 

29 150 ft (30 to 46 m) of low-conductivity confining zone sediments (NRC 2011b).

30 Recharge to the Chicot Aquifers underlying the STP site occurs to the northwest of the site, and 

31 discharge occurs generally to the east, south, and southeast of the site. The Shallow Chicot 

32 Aquifer outcrops at the land surface, is recharged a few miles northwest of the STP site in 

33 Matagorda County, and discharges to the Colorado River alluvium near the site. The Deep 

34 Chicot Aquifer outcrops and is recharged farther north and northwest in Wharton County. It 

35 discharges into Matagorda Bay and the Colorado River estuary approximately 5 mi (8 km) 

36 southeast of the STP site. In the upland areas of the aquifer watersheds, where the aquifer 

37 sediments are exposed at the land surface, infiltration from irrigation also contributes to 

38 recharge of both the Shallow and Deep Chicot aquifers. The Colorado River is a gaining stream 

39 where the Shallow and Deep Chicot aquifers discharge to the river (NRC 2011b). The alluvial 

40 aquifer adjacent to the river also undergoes bank storage, whereby water is retained in and 

41 discharged from the permeable alluvium of the river bank, with the rise and fall of the Colorado 

42 River.

43 Additionally, the MCR, as described in Section 2.1.7, is unlined and acts as a local recharge 

44 source for the Upper Shallow Chicot Aquifer. A series of 770 relief wells surround the MCR 

45 embankment and collect and discharge some of the seepage from the MCR and otherwise 

46 relieve hydrostatic pressure on the outer slope and toe of the embankment. Analyses 
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1 presented in the updated FSAR for STP, Units 1 and 2 (STPNOC 2009a), estimate total 

2 seepage from the MCR into the Upper Shallow Chicot Aquifer at 3,530 gpm or 5,700 ac-ft/yr 

(7 million m3 3 /yr)). These analyses also estimate that 68 percent of the seepage (2,390 gpm or 

3,850 ac-ft/yr (4.7 million m3 4 /yr)) from the MCR would be captured by the relief well system for 

5 an MCR maximum pool elevation of 49 ft (14.9 m) above MSL. More recent simulations of the 

6 MCR indicate approximately 50 percent capture (NRC 2011b).

7 Groundwater quality and aquifer yields dictate that the Deep Chicot Aquifer is the primary 

8 source of groundwater in the region. STP wells completed in the Deep Chicot Aquifer and used 

9 for groundwater production at the site are described in Section 2.1.7.2 (see also Figure 2–1). 

10 The nearest offsite public water supply wells are located in the communities of Selkirk and 

11 Exotic Isle, which are located adjacent to the STP site eastern boundary. Wells for these 

12 communities are approximately 1 mi (1.6 km) from the nearest STP production well, Well 7, and 

13 3.75 mi (6 km) from STP, Units 1 and 2 (see Figure 2–1). Two non-public water supply wells 

14 used for livestock watering are located about 1,800 ft (549 m) north of STP Well 5 and 2,230 ft

15 (680 m) west of STP Well 6. They are completed to depths of 500 and 400 ft (152 and 122 m)

16 and have screened intervals of 200 to 300 ft (61 to 91 m), respectively, above the screened 

17 intervals of the STP production wells (STPNOC 2010b).

18 Groundwater use from the Gulf Coast Aquifer system increased between 1940 and the 

19 mid-1980s. One cause was rice irrigation, and Matagorda County was among the counties 

20 where this occurred. As a result of subsidence issues and substantial increases in pumping lift, 

21 groundwater use has declined in the region. The Texas Water Development Board forecasts a 

22 decline in groundwater use from the Gulf Coast Aquifer through 2030. Matagorda County is 

23 projected to see a net decrease of 48 percent, with pumping decreasing from 21,528 gpm

24 (81,490 L/min) or 31 mgd in 1985 to 11,111 gpm (42,060 L/min) or 16 mgd in 2030 (Ryder and 

25 Ardis 2002). Decreased usage, consistent with this estimate, occurred through the year 2000; 

26 however, drought periods since then have resulted in an increase in groundwater usage.

27 Established under Texas State law (Water Code, Title 2, Subtitle E, Chapter 36), the Coastal 

28 Plains Groundwater Conservation District (CPGCD), which has the same boundaries as 

29 Matagorda County, has the authority and responsibility to define the modeled available 

30 groundwater in the district, to define the amount of groundwater being used in the district, and to 

31 issue permits based on the available groundwater resource. The NRC staff interviewed the 

32 manager of the CPGCD in July 2011 and learned that the current modeled available 

groundwater in the district (i.e., Matagorda County) is 46,000 ac-ft (57 million m3 33 ) annually or 

28,522 gpm (107,970 L/min), and the current usage is 36,000 ac-ft (44 million m3 34 ) or 

35 22,322 gpm (84,500 L/min). Annual permitted groundwater withdrawals for the period 2008 

through 2010 (i.e., permits are issued for a 3-year period) were 51,285 ac-ft/yr (63.2 million m3 36 ) 

37 or 31,800 gpm (120,400 L/min) (NRC 2011b). Groundwater use in the largely agricultural 

38 region encompassing STP fluctuates with the availability of surface water (e.g., with the 

39 occurrence of drought). Thus, annual permits that total in excess of the modeled available 

40 groundwater, an annual average value, is not unexpected. As presented in Section 2.1.7.2, 

41 annual average groundwater use by STP, Units 1 and 2 (i.e., 768 gpm), represents 

42 approximately 2.7 percent of the modeled available groundwater quantity in Matagorda County 

43 and 3.4 percent of current usage.

44 2.2.5.2 Groundwater Quality 

45 The Shallow Chicot Aquifer exhibits poor water quality and low productivity, and it is used in the 

46 vicinity of the STP site primarily for livestock watering. However, occasional domestic use is not 

47 precluded. Of 12 wells completed in the Shallow Chicot Aquifer within 10 mi (16 km) of the STP 
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1 site, 9 wells have TDS concentrations above the EPA secondary drinking water standard (DWS) 

2 of 500 mg/L (STPNOC 2010b).

3 As noted above, the MCR is unlined and acts as a local recharge source for the Upper Shallow 

4 Chicot Aquifer. Therefore, locally to the STP site, the MCR also influences the groundwater 

5 quality of the Upper Shallow Chicot Aquifer. A maximum tritium concentration of 

6 17,410 picocuries per liter (pCi/L) was reported for MCR waters in 1996 (STPNOC 2010b). 

7 While 50 to 68 percent of the MCR seepage into the aquifer is estimated to be removed by the 

8 series of 770 relief wells surrounding the MCR embankment, the remainder of the MCR waters 

9 seep into the aquifer, migrate downgradient, and discharge to the Colorado River southeast of 

10 the STP site. Monitoring of relief wells and monitoring wells around the MCR has shown that 

11 tritium from the MCR arrived at relief wells approximately 2 years after plant startup in 1988. It 

12 arrived at monitoring wells south of the MCR (wells MW-235 and MW-251) in 1999 and 2000 

13 and at monitoring wells west of the MCR (wells MW-258 and MW-259) in 2006 

14 (STPNOC 2007, 2011a). Since its first detection, the concentration of tritium in relief wells 

15 increased to a peak of approximately 7,500 pCi/L in 1999 and now varies between 5,000 and 

16 6,000 pCi/L. Since its first detection in 2000, the concentration of tritium in MW-251, which is 

17 located south of the MCR, peaked in 2001 and then declined somewhat, remaining close to the 

18 concentrations in the relief wells since then (i.e., 5,000 to 6,000 pCi/L). Since its first detection 

19 in 2006, the concentration of tritium in monitoring wells west of the MCR has increased, peaked, 

20 and remained steady since 2009 at around 2,500 pCi/L. Monitoring wells to the west of the 

21 MCR include wells slightly beyond the site boundary, which were observed by the NRC staff 

22 during the site audit. These wells are showing tritium levels consistent with those inside the site 

23 boundary. Sampling stations south of the MCR and on private property (MW-245 and MW-269) 

24 showed no detectable tritium in 2009 (STPNOC 2010a). All observed values for tritium are 

25 below the EPA primary DWS of 20,000 pCi/L (40 CFR Part 141). 

26 The 2006 annual environmental operating report (STPNOC 2007) presents information 

27 generated from sampling 18 groundwater wells outside the STP, Units 1 and 2, protected area 

28 and from sampling 16 groundwater wells within the STP, Units 1 and 2, protected area. 

29 Sampling of wells within the protected area resulted from STPNOC’s participation in the Nuclear 

30 Energy Institute’s (NEI’s) Groundwater Protection Initiative. During site characterization for 

31 STPNOC’s application for proposed Units 3 and 4, 28 groundwater observation wells were 

32 installed in 2006, and an additional 26 observation wells were installed in 2008 

33 (STPNOC 2010d). Since 2006, additional wells have been installed and added to the 

34 Environmental Monitoring Program to further characterize plumes within the protected area and 

35 originating from the MCR. For example, during 2008, three additional wells were installed in the 

36 protected area, and two additional wells were installed outside the protected area.

37 In 2006, sampling of wells completed in the Shallow Chicot Aquifer within the protected area 

38 provided eight positive results for tritium, all below the EPA primary DWS of 20,000 pCi/L 

39 (40 CFR Part 141). Eight wells had no detectable tritium. The results were attributed to 

40 seepage of MCR water into the Shallow Chicot Aquifer and underground pipe failures within the 

41 protected area. Two of these wells showed relatively higher values of tritium at 15,000 pCi/L 

42 and 1,250 pCi/L (STPNOC 2007). Tritium concentrations in the location of the high value in 

43 2006 decreased to 1,500 pCi/L by 2010. Individual wells exhibiting lower concentrations have 

44 shown trends upward over individual years and over the period from 2005 through 2010. 

45 However, well sampling within the protected area through 2010 (STPNOC 2011a) continues to 

46 show concentrations well below the EPA DWS for tritium. 

47 In response to the NEI initiative, STPNOC commissioned a report on the groundwater within the 

48 protected area (MACTEC 2009). Three sources of tritium in groundwater beneath the protected 
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1 area were identified: (1) seepage from the MCR, (2) leaks from the TDS pipeline, and 

2 (3) discharge from the turbine steam trap drain or steam condensate lines of each reactor. The 

3 first potential source is limited in concentration to the tritium levels in the MCR and subsequent 

4 decay in the groundwater pathway from the reservoir. The second source is described as 

5 having a maximum tritium concentration of 80,000 pCi/L (MACTEC 2009). The third source is 

6 described as having a maximum tritium concentration of less than 90,000 pCi/L 

7 (STPNOC 2011d). Within the protected area, the highest tritium concentration in groundwater 

8 was approximately 15,000 pCi/L in 2006 (STPNOC 2010b). The highest tritium concentration in 

9 the tendon galleries that circle the RCBs was less than 20,000 pCi/L in 2010 (STPNOC 2011d). 

10 The latter measurement may be indicative of tritium concentrations in groundwater resulting 

11 from discharge from the steam condensate lines. STPNOC has evaluated releases inside the 

12 protected area and concluded that no release is occurring from an unidentified pathway, no 

13 radioactive material is being released off site, and there is no impact on drinking water or on 

14 public health and safety (STPNOC 2011a).

15 The monitoring program has observed tritium in the shallow aquifer for several years in wells to 

16 the south of the MCR. The tritium movement is consistent with simulations conducted during 

17 licensing of STP, Units 1 and 2, and shows concentrations below the EPA DWS. In 2010, the 

18 monitoring program (STPNOC 2011a) results indicated stable tritium concentrations in 

19 groundwater wells surrounding the MCR. Higher levels reported in recent years are consistent 

20 with drought conditions and low MCR water levels. From the latest STP groundwater 

21 monitoring data, the peak groundwater tritium concentration in 2010 was 6,600 pCi/L—well 

22 below the EPA DWS of 20,000 pCi/L (STPNOC 2011b).

23 Based on groundwater data from 2006 through 2008 presented in the FSAR for proposed STP, 

24 Units 3 and 4 (STPNOC 2010c), the piezometer head gradient from the existing STP, Units 1 

25 and 2, to the site boundary to the east is approximately 3 ft (0.9 m), and the distance is 

26 approximately 1 mi (1.6 km) (5,280 ft or 1,609 m). Representative values for saturated 

27 hydraulic conductivity and effective porosity of the lower shallow aquifer are 72 ft/day (22 m/day) 

28 and 0.31, respectively. The lower shallow aquifer is the more likely pathway for releases in the 

29 vicinity of the RCBs to offsite receptors (see Section 2.2.5.1) (NRC 2011b). Using these data, 

30 the travel time from STP, Units 1 and 2, to the site boundary is approximately 100 years. Such 

31 a travel time within the shallow aquifer presents adequate time for tritium source concentrations 

32 to decay (i.e., tritium has a 12.3 year half-life) to levels below the EPA DWS.

33 2.2.6 Aquatic Resources

34 2.2.6.1 Colorado River and Matagorda Bay

35 The Colorado River extends approximately 862 mi (1,387 km) from the high plains to the coastal 

36 marshes in Matagorda County. It is one of the largest river systems within the State of Texas. 

The drainage area for the lower Colorado River basin includes approximately 22,700 mi2 37

(58,792 km2 38 ), from Lake O.H. Ivie in Mills County, Texas, to Matagorda Bay (TWDB 2007).

39 STP is located in the Texas coastal plain physiographic province. The section of the Colorado 

40 River near STP is a diverse, fluvial system that meanders through the coastal plain providing 

41 sediments and nutrients to Matagorda Bay (ENSR 2008c). The river in this area is generally 

42 surrounded by steep banks. Little vegetation can grow on the steep banks, but some 

43 bottomland forests and wetlands occur on land adjacent to the river (ENSR 2008c).

44 The Colorado River is tidally influenced near STP, which means that saltwater from Matagorda 

45 Bay and the Gulf of Mexico regularly flows upstream and mixes with freshwater from the river. 

46 During periods of low flow, the salinity can reach as high as 20 parts per thousand (ppt) near 

47 STP (ENSR 2008c). Flow from the gulf and bay influences the aquatic community near STP by 
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1 transporting organisms and increasing the salinity in the river. The distribution and density of 

2 aquatic plants and animals living in tidally influenced rivers is often determined by salinity 

3 concentrations.

4 Environmental History. Freshwater flow between the Colorado River and Matagorda Bay has 

5 important ecological implications. Flow from the Colorado River can increase the biological 

6 productivity within Matagorda Bay by providing freshwater, soil, and debris, which can facilitate 

7 the growth of marsh habitats. Saltwater flow from the bay to the river can influence the species 

8 distribution and diversity within the river by transporting organisms up the river and providing 

9 habitat (e.g., higher salinity) for estuarine and marine organisms.

10 Various development projects have influenced the flow between the Colorado River and

11 Matagorda Bay in the past 100 years. Prior to the 1920s, the Colorado River flowed directly into 

12 Matagorda Bay. In an attempt to control flooding, the U.S. Army Corps of Engineers (USACE) 

13 dredged a channel down the middle of Matagorda Bay (Holtcamp 2006). The USACE lined the 

14 channel with the dredged mud, which divided the bay into an eastern and western portion. As a 

15 result of the lined channel, the water from the Colorado River then flowed directly into the Gulf 

16 of Mexico (ENSR 2008c).

17 Dredging projects in the 1950s and 1990s reestablished flow between the Colorado River and 

18 Matagorda Bay. In the 1950s, the USACE dredged the Tiger Island Channel through the west 

19 side of Matagorda Bay, re-establishing flow between the river and the bay. In part because of

20 ecological importance for freshwater to reach the bay, the USACE conducted a series of 

21 dredging projects to increase the flow from the river to the bay in the 1990s (Holtcamp 2006). In 

22 1990, the USACE constructed a deeper river diversion channel northwest of the Tiger Island 

23 Channel. In 1991, the USACE constructed two dams to divert the river flow, including one 

24 across the Tiger Island Channel (called the Tiger Island Cut Dam, recently renamed to Parker’s 

25 Cut) and a diversion dam across the river channel on Matagorda Peninsula. By July 1992, the 

26 Colorado River flowed directly into Matagorda Bay, through the Gulf Intracoastal Waterway 

27 (GIWW) and the newly constructed diversion channel. Wilber and Bass (1998) determined that 

28 the changes in freshwater inflow to Matagorda Bay over time, and the changes to flow from the 

29 Gulf of Mexico into the Colorado River, have likely influenced the aquatic communities 

30 historically in the river and bay.

31 Common Taxa. The most comprehensive studies of the aquatic community within the lower 

32 Colorado River near STP are studies conducted as part of the licensing processes for STP, 

33 Units 1, 2, 3, and 4. Below is a brief summary of the aquatic surveys conducted near STP. 

34 Although the owner of the STP site has changed over time, the owner is referred to as STPNOC 

35 for simplicity purposes below.

36 • 1973 to 1974: STPNOC sampled phytoplankton (microscopic floating 

37 photosynthetic organisms), zooplankton (small animals that float, drift, or 

38 weakly swim in the water column, including fish and invertebrate eggs and 

39 larvae), juvenile and adult macroinvertebrates (invertebrates visible without a 

40 microscope), and juvenile and adult fish (HPLC 1974). NRC (1975) 

41 summarized these results in the final environmental statement for the 

42 construction of STP, Units 1 and 2. 

43 • 1975 to 1976 and 1983 to 1984: Due to the usually wet conditions during the 

44 1973 to 1974 surveys, STPNOC conducted additional fish surveys in the 

45 Colorado River in 1975 to 1976 and 1983 to 1984 (McAden 1984, 1985). 

46 NRC (1986) summarized these results in the final environmental statement 

47 for the operation of STP, Units 1 and 2. 
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1 • 2007 to 2008: In support of STPNOC’s application to build and operate STP, 

2 Units 3 and 4, STPNOC sampled macroinvertebrates and fish within the 

3 Colorado River near STP (ENSR 2008c; STPNOC 2011d). NRC (2011b) 

4 summarized these results in its final EIS for the proposed construction and 

5 operation of STP, Units 3 and 4.

6 Since the Colorado River diversion project, which increased the flow between the Colorado 

7 River and Matagorda Bay, species diversity and the number of estuarine-marine species 

8 increased in the Colorado River near STP (NRC 2011b). Because of this change, the summary 

9 of aquatic organisms focuses on the most current studies. An analysis of the change in the 

10 aquatic community since the beginning of STP operations is provided in Section 4.5.2.

11 Phytoplankton: Phytoplankton are microscopic floating photosynthetic organisms that form the 

12 basis of the food chain. Phytoplankton play key ecosystem roles in the distribution, transfer, 

13 and recycling of nutrients and minerals. STPNOC most recently surveyed the phytoplankton 

14 community in the summer of 1973 in the lower Colorado River and an adjacent stretch of

15 GIWW. STPNOC collected 524 taxa, representing six major divisions (NRC 1975, 2011b). 

16 Diatoms and cynobacteria (blue-green algae) dominated the phytoplankton community. 

17 Diatoms were more numerous at the bottom-water samples, and cyanobacteria and 

18 dinoflagellates were predominant in the water column.

19 Zooplankton: Zooplankton are small animals that float, drift, or weakly swim in the water 

20 column. Zooplankton include, among other forms, fish eggs and larvae with limited swimming 

21 ability, larvae of benthic invertebrates, medusoid forms of hydrozoans, copepods, shrimp, and 

22 krill (order Euphausiids).

23 STPNOC surveyed the lower Colorado River and an adjacent stretch of GIWW in 1973 to 1974 

24 for macrozooplankton (HPLC 1974). STPNOC collected 319 zooplankton species, which 

25 included protozoans (101 species), rotifers (75 species), copepods (31 species), and 

26 cladocerans (27 species) (NRC 1975). The survey showed that the zooplankton community 

27 structure changed based on salinity, such that during periods of higher salinity (e.g., low river 

28 flow and strong incoming tides), species diversity increased at upstream stations.

29 STPNOC most recently surveyed macrozooplankton in 1975 to 1976 and 1983 to 1984 at five 

30 stations in the lower Colorado River (Figure 2–2). The abundance and occurrence of 

31 invertebrate eggs and larvae were greatest downstream (Station 5); these decreased in fresher 

32 water upstream (NRC 1986). In the 1975 to 1976 samples, both freshwater and 

33 estuarine-marine decapod larvae dominated the macrozooplankton community from May to 

34 September, and estuarine-marine decapod larvae dominated the community from October to 

35 December (NRC 1986). The abundance and diversity of decapod larvae were lowest from 

36 January through April, when the copepod Acartia tonsa was most prevalent (NRC 1986). In 

37 1983, the most abundant macrozooplankton were cladocerans, Malacostraca species, and 

38 copepods (NRC 1986). In 1984, the most abundant macrozooplankton were immature stages 

39 of the Harris mud crab (Rhithropanopeus harrissi), ghost shrimp (Callianassa spp.), and jellyfish 

40 (family Cnidaria) (NRC 1986).

41 STPNOC also collected commercially important species, including early life stages of blue crab 

42 (Callinectes sapidus), white shrimp (Litopenaeus setiferus), and brown shrimp 

43 (Farfantepenaeus aztecus, formerly known as Penaeus aztecus). In general, the density of 

44 these species was greatest in higher salinity water (e.g., in the salt wedge or further 

45 downstream), and lower densities occurred near the STP site (NRC 1975, 1986).

46 STPNOC most recently collected ichthyoplankton (fish eggs and larvae) in 1975 to 1976 and 

47 1983 to 1984 at five stations in the lower Colorado River (Figure 2–2). NRC (1986) reported the 
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1 highest densities of ichthyoplankton from May to October 1975 and March to April 1976. 

2 Densities of ichthyoplankton was highest in higher salinity waters (NRC 1986). The most 

3 common species were often estuarine or marine species, such as Gulf menhaden (Brevoortia 

4 patronus), bay anchovy (Anchoa mitchelli), Atlantic croaker (Micropogonia undulatus), and 

5 naked goby (Gobiosoma bosc) (NRC 1986). In early May and August, when the salinity 

6 dropped in the Colorado River, the abundance of ichthyoplankton shifted to freshwater drum 

7 (Aplodinotus grunniens) and cyprinid species (NRC 1986). At the sampling station next to the 

8 RMPF, STPNOC collected three species (bay anchovy, darter goby (Ctenogobius boleosoma), 

9 and naked goby), which were three of the most commonly collected species in the survey along 

10 the lower Colorado River.

11 Survey results suggest that the lower Colorado River near STP is an estuarine nursery ground 

12 for many commercially important species including Gulf menhaden, Atlantic croaker, sand 

13 seatrout (Cynoscion arenarius), spotted seatrout (C. nebulosus), spot croaker (Leiostomus 

14 xanthurus, also called spot), sheepshead (Archosargus probatocephalus), pigfish (Orthopristis 

15 chrysopterus), black drum (Pogonias cromis), red drum (Sciaenops ocellatus), and southern 

16 flounder (Paralichthys dentatus) (NRC 1986).

17 Adult and Juvenile Macroinvertebrates: STPNOC sampled adult and juvenile 

18 macroinvertebrates in 1975 to 1976 at eight sampling stations in the Colorado River 

19 (Figure 2–2). In 1983 to 1984, STPNOC sampled at Station 2, which is closest to the RMPF

20 (Figure 2–2). In 2007 to 2008, STPNOC sampled along a 9-mi (14-km) stretch of the lower 

21 Colorado River extending from the GIWW north to the FM 521 bridge (Figure 2–3 and 

22 Figure 2–4). Within this portion of the river, STPNOC divided the area into three 3-mi (5-km) 

23 segments and randomly sampled each segment monthly from June 2007 through May 2008. 

24 Within each month, STPNOC collected samples during a 2-day period randomly selected each 

25 month. STPNOC collected samples if the river flow was 5,000 cfs or less to reduce variability in 

26 sampling conditions.
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1 Figure 2–2. The STP Site and 1975 to 1976 Aquatic Ecology Sampling Location

2 (NRC 2011b) 

 3 
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1 Figure 2–3. The STP Site and 2007 to 2008 Aquatic Ecology Sampling 

2 Locations from Segment C through the Upstream Portion of Segment B 

3 (NRC 2011b) 

 4 
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1 Figure 2–4. The STP Site and 2007 to 2008 Aquatic Ecology Sampling 

2 Locations from the Downstream Portion of Segment B through Segment A 

3 (NRC 2011b) 
Affected Environment 

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1 All studies used seines and trawls to sample macroinvertebrates. In 2007 to 2008, STPNOC 

2 also used gill nets and hoop nets primarily to capture fish (ENSR 2008c). However, STPNOC 

3 collected a few macroinvertebrates in gill nets and hoop nets; therefore, the methodology and 

4 results of these sampling programs is presented below. ENSR (2008c) used the four different 

5 types of gear to capture a variety of taxa in terms of size (or life stage) and habitat location 

6 (e.g., open water vs. benthic). The information below describes the sampling gear used in the 

7 2007 to 2008 study within each of the three sampling segments (segments A, B, and C) 

8 (Figure 2–3 and Figure 2–4): 

• Trawls

•

9 : STPNOC conducted two tows, each for 10 minutes, with a 6.1-m 

10 (20-ft) otter trawl fitted with a 3.5-cm (1.4-in.) stretched mesh and doors 

11 (i.e., otter boards) measuring 46 cm by 91 cm (18 in. by 36 in.) attached to 

12 each wing of the net. The trawl was designed to capture benthic or demersal 

13 fishes and macroinvertebrates.

Gill nets

•

14 : STPNOC set one gill net perpendicular to the shoreline. It set the 

15 net within 1 hour of sunset and retrieved it at sunrise the following morning. 

16 The gill net was 33-m (108-ft) long, 1.2-m (3.9-ft) deep, and consisted of 

17 10.2-cm (4-in.) stretched monofilament mesh. It was designed to capture 

18 adult fish using shoreline habitats.

Hoop nets

•

19 : STPNOC placed one set of hoop nets within 1 hour of sunset and 

20 retrieved them at sunrise the following morning. Hoop nets consisted of a 

21 multi-chambered conical net that was 3.6-m (12-ft) long with one 1-m (3-ft) 

22 diameter hoop at the beginning, followed by smaller hoops, and covered with 

23 2.5-cm (1-in.) stretched mesh netting. Each hoop net had wings that were 

24 7.5-m (25-ft) long by 1.8-m (5.9-ft) deep and comprised of 5-cm (2-in.) 

25 stretched mesh. Hoop nets were designed to capture sub-adult fish using 

26 shoreline habitats.

Seines

34 The most abundant invertebrate species in the 1975 to 1976 and 1983 to 1984 studies were 

35 river and white shrimp (McAden et al. 1984, NRC 1986). At Station 1, the most upriver station 

36 near STP, brown shrimp was the most abundant species in trawl samples, and blue crabs were 

37 the most abundant species in seine samples (NRC 2011b). At Station 2, which is closest to the 

38 RMPF, STPNOC collected river shrimp, white shrimp, blue crabs, and crayfish (NRC 1986).

27 : STPNOC conducted two seine pulls per month for 15.2 m (50 ft) 

28 parallel to the shoreline. Seines were comprised of a 19-mm (0.75-in.) mesh 

29 net that measured 18.3-m (60-ft) long and 1.8-m (6-ft) deep. In the center 

30 was a 1.8 m (6 ft) by 1.8 m (6 ft) by 1.8 m (6 ft) bag that was covered in 

31 13-mm (0.5-in.) stretched mesh. Seines were designed to capture 

32 macroinvertebrates and juvenile and sub-adult fishes using shoreline 

33 habitats.

39 In the 2007 to 2008 study, ENSR (2008c) reported the most common species to be white 

40 shrimp (30 percent), grass shrimp (Palaemonetes pugio) (29 percent), brown shrimp 

41 (7 percent), and blue crab (4 percent) (Table 2–1). ENSR (2008c) collected macroinvertebrates 

42 most often in the river segment with the highest salinity (segment A) and least often in the river 

43 segment with the lowest salinity (segment C) (Figure 2–3 and Figure 2–4). ENSR (2008c) 

44 reported the greatest density of macroinvertebrates and fish during the following periods:

• Trawls

•

45 : October through January, 

46 Gill Nets: September through December and March through May, 
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• Hoop Nets

•

1 : October through February and April through June, and

Seines

3 Brown, pink (Farfantepenaeus brasiliensis), and white shrimp are of commercial importance in 

4 the vicinity of the STP site (TPWD 2002; USACE 2007). STPNOC observed various life stages 

5 of brown and white shrimp in all three studies (NRC 1986; STPNOC 2008c). STPNOC only 

6 observed pink shrimp during the 1984 to 1985 studies (NRC 1986).

2 : January through April. 

7 Table 2–1. Macroinvertebrates Collected in the Colorado River 

8 by Gear Type, 2007 to 2008

Common Name Scientific Name Seine Gill Net

Hoop 

Net Trawl Total % of Total 

Atlantic brief squid Lolliguncula brevis 1 0 0 30 31 <1

Atlantic seabob Xiphopenaeus kroyeri 0 0 0 127 127 2 

Blue crab Callinectes sapidus 190 2 3 77 272 4 

Brown shrimp 

Farfantepenaeus 

aztecus 264 0 0 192 456 7 

Grass shrimp Palaemonetes pugio 1,762 0 0 1,762 29

white shrimp Litopenaeus setiferus 584 0 0 2,870 3,454 30

Other 11 0 1 12 24 <1

Total invertebrates 2,812 2 4 3,308 6,126

Source: ENSR 2008c 

9 Adult and Juvenile Fish: STPNOC sampled adult and juvenile fish in 1975 to 1976 at eight 

10 sampling stations in the Colorado River (Figure 2–3). In 1983 to 1984, STPNOC sampled at 

11 Station 2, which is closest to the RMPF (Figure 2–3). In 2007 to 2008, STPNOC sampled along 

12 a 9-mi (14-km) stretch of the lower Colorado River extending from the GIWW north to the 

13 FM 521 bridge (Figure 2–3 and Figure 2–4). All studies used seines and trawls to sample fish. 

14 In 2007 to 2008, STPNOC also used gill nets, hoop nets, and trawls (ENSR 2008c). 

15 ENSR (2008c) followed the same methodology described above for the macroinvertebrate 

16 sampling.

17 The most abundant fish species in the 1974 to 1975 study were Gulf menhaden, bay anchovy, 

18 Atlantic croaker, and striped mullet (Mugil cephalus) (NRC 1986). All of these species, except 

19 for menhaden, were most abundant at sampling stations furthest down the river (NRC 1986). 

20 Similarly, STPNOC only collected many of the commercially important estuarine species 

21 (e.g., red drum and southern flounder) at the most downstream station, Station 5. The density 

22 of menhaden, on the other hand, was greatest at the most upstream station, Station 1.

23 In the 2007 to 2008 study, STPNOC (2008c) reported the most common species to be Gulf 

24 menhaden (35 percent), striped mullet (14 percent), black drum (Pogonia cromis) (12 percent), 

25 and Atlantic croaker (9 percent) (Table 2–2). All other species comprised 3 percent or less of 

26 the total fish collected. ENSR (2008c) collected fish most often in the river segments with the 

27 highest salinity (segments A and B) and least often in the river segment with the lowest salinity 

28 (segment C) (Figure 2–3 and Figure 2–4).
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1 Table 2–2. Fish Collected in the Colorado River by Gear Type, 2007 to 2008

Common Name Scientific Name Seine Gill Net

Hoop 

Net Trawl Total

% of 

Total 

Atlantic croaker Micropogonias undulatus 562 1 0 482 1,045 9 

Bay anchovy Anchoa mitchilli 24 0 0 264 288 2 

Black drum Pogonias cromis 1 1 1 1,360 1,363 12

Blue catfish Ictalurus furcatus 51 22 3 677 753 6

Channel catfish Ictalurus punctatus 22 0 2 6 30 <1

Gafftopsail catfish Bagre marinus 0 9 0 183 192 2

Gizzard shad Dorosoma cepedianum 8 0 2 52 62 <1

Gulf menhaden Brevoortia patronus 2,960 5 2 1,076 4,043 35

Hardhead catfish Ariopsis felis 0 1 1 252 254 2

Red drum Sciaenops ocellatus 8 8 38 25 79 <1

Sailfin molly Poecilia latipinna 150 0 0 0 150 1

Sand seatrout Cynoscion arenarius 22 5 0 294 321 3

Sharptail goby Oligolepis acutipennis 39 0 0 0 39 <1

Sheepshead Archosargus probatocephalus 14 1 6 48 69 <1

Sheepshead 

minnow Cyprinodon variegatus 79 0 0 7 86 <1

Silver perch Bairdiella chrysoura 0 0 0 350 350 3

Smallmouth 

buffalo Ictiobus bubalus 0 32 5 0 37 <1

Spot croaker Leiostomus xanthurus 88 0 1 156 245 2 

Spotted seatrout Cynoscion nebulosus 0 4 0 53 57 <1

Star drum Stellifer lanceolatus 0 0 0 86 86 <1

Striped mullet Mugil cephalus 1,676 0 1 1 1,678 14

White mullet Mugil curema 181 0 0 2 183 2 

Other 109 15 33 78 235 2

Total Fish 5,994 104 95 5,452 11,645

Source: ENSR 2008c

2 Species Richness: In the 2007 to 2008 studies, ENSR (2008c) calculated the species richness, 

3 or number of fish and macroinvertebrate species collected, within each river segment and for 

4 each type of sampling gear. ENSR (2008c) reported the highest species richness in the river 

5 segment with the highest salinity (segment A) for trawl, seine, and gill net samples (Table 2–3). 

6 The species richness was similar across all three-river segments for hoop net samples 

7 (Table 2–3).
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1 Table 2–3. Species Richness (number of species) in Three River Segments by Gear Type

River Segment

Gear Type A B C

Trawl 37 29 24

Seine 38 35 22

Gill nets 14 12 9

Hoop nets 11 12 12

Source: ENSR 2008c 

2 STPNOC’s studies in the 1970s and 1980s also found greater species diversity and density 

3 further downstream in higher salinity waters (NRC 1975, 1986). NRC (1975) attributed the 

4 lower density and diversity near the STP site to the relatively large and frequent fluctuations in 

5 salinity. Downstream areas, on the other hand, exhibit relatively stable salinity, which allows for 

6 the establishment of a variety of estuarine and marine species assemblages.

7 2.2.6.2 Onsite aquatic features

8 STP is located approximately 23 ft (7 m) above MSL on a site with relatively flat topography. 

9 Water covers approximately 58 percent of the 12,220 ac (4,945 ha) STP site (STPNOC 2010b). 

10 The onsite aquatic features include the MCR, the ECP, several sloughs, drainage areas, 

11 wetlands, and Kelly Lake.

12 Construction activities for STP, Units 1 and 2, extensively altered several aquatic features on 

13 the STP site. For example, during the building of the MCR, STPNOC removed up to 65 percent

14 of the drainage area for Little Robbins Slough in the southern part of the site (NRC 1975). 

15 STPNOC also created a new channel for the slough, which is the same as the current 

16 configuration (NRC 2011b). The reconfiguration of Little Robbins Slough reduced the annual 

17 freshwater runoff into onsite marshes and marshes south of the STP site. Reduced flow can 

18 displace freshwater species and reduce the quality of nursery grounds for estuarine-dependent 

19 organisms (NRC 1975). As a result of seepage flow from the MCR into the slough, NRC (1986) 

20 estimated the total long-term average annual reduction of freshwater input into the marshes to 

21 be 6 percent. NRC (1986) concluded that, at this rate, the reduction in flow of freshwater from 

22 the slough into the marshes, and any subsequent changes in salinity or nutrient input, were not 

23 expected to alter the structure and function of the upper marsh aquatic community (NRC 1986).

24 Below is a description of the main aquatic features currently located on the STP site.

25 Main Cooling Reservoir. The MCR is a 7,000-ac (2,833-ha), man-made impoundment that is 

26 the normal heat sink for waste heat generated during operations of STP, Units 1 and 2. 

27 STPNOC maintains the water level and quality (e.g., total dissolved solids) in the MCR by 

28 pumping water from the Colorado River through the RMPF, as described in Section 2.1.6. A 

29 variety of aquatic organisms currently inhabit the MCR (ENSR 2008a; STPNOC 2010b). 

30 Aquatic organisms were likely introduced into the MCR when small life stages (e.g., eggs or 

31 larvae) or species were entrained during the initial filling and subsequent refilling of the MCR.

32 ENSR (2008a) collected samples of the aquatic community within the MCR four times a year 

33 from May 2007 through April 2008. ENSR (2008a) sampled the aquatic community at fixed 

34 stations within five regions of the MCR. Each region was varying distance from the cooling 

35 water discharge and CWIS. ENSR (2008a) used four different types of gear to capture a variety 

36 of taxa in terms of size (or life stage) and habitat location (e.g., open water vs. benthic). 

37 ENSR (2008a) used the following gear types within each region that was sampled:
Affected Environment 

2-34

• Trawls

•

1 : STPNOC conducted five tows, each for 10 minutes, with a 6.1-m 

2 (20-ft) otter trawl fitted with a 3.5-cm (1.4-in.) stretched mesh and doors 

3 (i.e., otter boards) measuring 46 cm by 91 cm (18 in. by 36 in.) attached to 

4 each wing of the net. The trawl was designed to capture benthic or demersal 

5 fishes and macroinvertebrates.

Gill nets

•

6 : STPNOC set three gill nets within 1 hour of sunset and retrieved 

7 them at sunrise the following morning. Gill nets were 91.4-m (300-ft) long, 

8 3.0-m (10-ft) deep, and consisted of four separate panels measuring 

9 approximately 22.9-m (75-ft) in length and comprised of 2.5, 5.1, 7.6, and 

10 10.2-cm (1, 2, 3, and 4-in.) stretched mesh connected in ascending order. 

11 The grill nets were designed to capture adult fish using open water surface 

12 habitats.

Seines

•

13 : STPNOC conducted one seine pull per sampling event. Seines 

14 were comprised of 6.4-mm (0.25-in.) mesh net and measured 30.5-m (100-ft) 

15 long and 3.0-m (10-ft) deep. Seines were designed to capture small 

16 macroinvertebrates and fish using shoreline habitats.

Plankton nets

ENSR (2008a) collected 11,605 fish and invertebrates using gill nets, seines, and trawls (

17 : STPNOC conducted three oblique plankton tows through all 

18 depths of water per sampling event. It used a low speed Henson plankton 

19 net with a with a dimension of 30-cm (12-in.) mouth width by 120-cm (47-in.) 

20 length and covered with mesh size of 0.363 mm (0.014 in.). Plankton nets 

21 were designed to capture pelagic ichthyoplankton, invertebrate larvae, and 

22 small invertebrates.

23 Table 

24 2–4). ENSR (2008a) identified 25 species of fish and invertebrates. Threadfin shad (Dorosoma 

25 petenense) was the most commonly collected species, representing 62 percent of all fish and 

26 invertebrates collected using gill nets, seine pulls, or trawls. Other commonly collected species 

27 include inland silverside (Menidia beryllina) (18 percent), rough silverside (Membras martinica) 

28 (12 percent), and blue catfish (Ictalurus furcatus) (3 percent) (ENSR 2008a). Blue crab was the 

29 most commonly collected invertebrate, and it comprised less than 1 percent of the total 

30 organisms collected using gill nets, seines, and trawls.

31 ENSR (2008a) collected a total of 5,362 organisms using plankton nets (Table 2–5). Greater 

32 than 99 percent of the organisms collected were invertebrates (crustaceans), and less than 

33 1 percent was ichthoplankton (fish eggs and larvae). The most common species (84 percent of 

34 all plankton net samples) collected were Harris mud crab larvae (ENSR 2008a). ENSR (2008a) 

35 collected two fish taxa—clupeid shad (Clupeidae spp.) and gobi (Gobiidae spp.).

36 The fish and invertebrates collected in the MCR suggest that a robust aquatic community has 

37 developed in the MCR. This community is more representative of an estuarine river rather than 

38 a freshwater impoundment, likely because the source of fish and invertebrates is from the 

39 Colorado River during filling of the MCR.

40 While a diverse aquatic community exists in the MCR, its organisms no longer contribute to the 

41 riverine ecosystem because they are separate from the Colorado River. In addition, the 

42 organisms are not available for harvest, and there is no public access or use of the MCR. The 

43 USACE has determined that the MCR is not waters of the U.S. (USACE 2009), and TCEQ has

44 stated that the MCR is not waters of the State (TCEQ 2007).
Affected Environment

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1 Table 2–4. Fish and Invertebrates Collected in the MCR by Gill Nets, 

2 Seines, and Trawls, 2007 to 2008.

Common Name Fish Scientific Name Gill Net Seine Trawl Total % of Total

Atlantic croaker Micropogonias undulatus 17 86 103 <1

Black drum Pogonias cromis 26 26 <1

Blue catfish Ictalurus furcatus 308 35 50 393 3 

Bluegill Lepomis macrochirus 31 31 <1

Channel catfish Ictalurus punctatus 3 21 6 30 <1

Common carp Cyprinus carpio carpio 97 9 106 <1

Freshwater drum Aplodinotus grunniens 7 3 39 49 <1

Gizzard shad Dorosoma cepedianum 45 28 73 <1

Gulf menhaden Brevoortia patronus 4 1 5 <1

Inland silverside Menidia beryllina 2,068 2,068 18

Ladyfish Elops saurus 36 1 37 <1

Gray (mangrove) 

snapper Lutjanus griseus 2 2 <1

Naked goby Gobiosoma bosc 3 3 <1

Needlefish Strongylura exilis 1 1 <1

Pinfish Lagodon rhomboides 3 1 4 <1

Red drum Sciaenops ocellatus 1 1 <1

Rough silverside Membras martinica 1,362 1,362 12

Sheepshead minnow Cyprinodon variegatus 4 4 <1

Smallmouth buffalo Ictiobus bubalus 2 2 <1

Spotted gar Lepisosteus oculatus 1 2 3 <1

Striped mullet Mugil cephalus 1 41 42 <1

Threadfin shad Dorosoma petenense 6,463 768 7,231 62

White mullet Mugil curema 7 7 <1

Invertebrates <1

Blue crab Callinectes sapidus 11 2 6 19 <1

Rangia clam Rangia cuneata 3 3 <1

Total 515 10,091 999 11,605

Source: ENSR 2008a
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1 Table 2–5. Fish and Invertebrates Collected in the MCR by Plankton Tows, 

2 2007 to 2008

Common Name Fish Taxa Total % of Total

Clupeid shad Clupeidae spp. 15 <1

Gobi Gobiidae spp. 2 <1

Invertebrates

Water flea Cladocera spp. 8 <1

Amphipods Amphipoda spp. 1 <1

Copepods Copepoda spp. 22 <1

Fish lice Branchiura spp. 1 <1

Decapods Panopeidae spp. 539 10

Harris mud crab Rhithropanopeus harrissi 4,582 85

Decapod zoea Decapoda spp. 153 3

Brachyuran decapod Brachyura spp. 29 1

Mysid shrimp Mysida spp. 2 <1

Bivalvia Bivalvia spp. 3 <1

Unidentified 5 <1

Total 5,362

Source: ENSR 2008a 

3 Essential Cooling Pond. The ECP is a 46-ac (19-ha) cooling pond and serves as the ultimate 

4 heat sink for Units 1 and 2. ENSR (2002) conducted a survey of the ECP and indentified two 

5 fish species: sailfin molly (Poecilia latipinna) and sheepshead minnow (Cyprinodon variegates). 

6 ENSR (2002) captured fewer fish near the discharge structure compared to elsewhere in the 

7 ECP. ENSR (2007, 2008c) identified sailfin molly and sheepshead minnow in the main 

8 drainage channel (MDC) and the Colorado River, and ENSR (2008a) indentified sheepshead 

9 minnow in the MCR.

10 Other Aquatic Features. Other onsite aquatic features include the Little Robbins Slough, 

11 wetlands, Kelly Lake, and drainage areas.

12 Little Robbins Slough is a stream that flows across the site, from the northwest corner, along the

13 western edge of the MCR embankment, and then out the southwest corner. This water flow is

14 critical to the function and structure of the marshes both on site and south of the site (Mad 

15 Island Wildlife Management Area (WMA) and Clive Runnells Family Mad Island Marsh 

16 Preserve). These marshes provide nursery grounds for juvenile fish and shellfish. The water 

17 from Little Robbins Slough eventual flows into the GIWW.

18 Kelly Lake is located in the northeast edge of the MCR embankment (STPNOC 2010d). The 

19 lake covers approximately 34 ac (14 ha) and is primarily fed by drainage areas but may also 

20 receive groundwater discharge (STPNOC 2010d). The NRC staff is not aware of any aquatic 

21 ecology surveys of Kelly Lake (NRC 1975, 1986, 2011b; STPNOC 2010b).
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1 The STP site also includes numerous drainage areas, many of which are man-made ditches 

2 (NRC 2011b). NRC (1975, 1986) included a description of the prevalent aquatic communities 

3 on the STP site in drainage areas. The most common species from these studies include the 

4 following: grass shrimp (Palaemonetes kadiakensis; also known as Mississippi grass shrimp),

5 crayfish (possibly of several genera), blue crab, red shiner (Cyprinella lutrensis), mosquitofish 

6 (Gambusia affinis), silverband shiner (Notropis shumardi), sailfin molly, green sunfish (Lepomis 

7 cyanellus), warmouth (L. gulosus), bluegill (L. macrochirus), white crappie (Pomoxis annularis), 

8 tidewater silverside (Menidia peninsulae), striped mullet, and several species of killifish (Family 

9 Cyprinodontidae, likely Lucania spp. and Fundulus spp.). NRC (1975, 1986) reported aquatic 

10 invertebrates, such as the early life stages of midges, beetles, mayflies, biting midges, 

11 dragonflies, and damselflies. The fish and invertebrates found in drainage areas are common 

12 species along the Texas coastline, and most are generally tolerant of salinity and water 

13 temperature fluctuations (Hassan-Williams and Bonner 2009; NRC 1975, 1986, 2011b; 

14 STPNOC 2010d; Thomas et al. 2007).

15 More recently, ENSR (2007) conducted a rapid bio-assessment of the MDC. The MDC is a 

16 150-m (492-ft) unlined channel that runs north of the proposed STP, Units 3 and 4, power block, 

17 crosses the existing railroad track, and eventually joins the Little Robbins Slough west of the 

18 MCR (ENSR 2007; NRC 2011b). STPNOC relocated the MDC further north of the proposed 

19 STP, Units 3 and 4, power block as part of STPNOC’s proposal to build Units 3 and 4 

20 (STPNOC 2010e). There is no continual flow of water in the MDC. Saturated soils and possible 

21 groundwater support shallow pooled areas. Water depth increases during rain events, and 

22 water drains into Little Robbins Slough during high flows (ENSR 2007; NRC 2011b).

23 ENSR (2007) conducted the survey using seine nets and followed a modified version of EPA’s 

24 rapid bioassessment protocols (Barbour et al. 1999). ENSR (2007) identified 11 fish taxa, 

25 2 invertebrate taxa, and 1 turtle. The three most common species were largemouth bass 

26 (Micropterus salmoides), mosquitofish, and sailfin mollies. Other species included other sunfish 

27 species (redear sunfish (Lepomis microlophus), pumpkinseed (L. gibbosus), and bluegill), 

28 killifish (Bayou killifish (undulus pulverous), Gulf killifish (Fundulus grandis), sheepshead 

29 minnows), gobies (Gobiidae), inland silverside, crayfish (several genera occur in the area, 

30 e.g., Procambarus spp.), grass shrimp, and red eared slider (Chrysemys scripta). Similar to the 

31 fish and invertebrates that inhabited drainages areas in 1970s and 1980s, the taxa found in the 

32 MDC are common species along the Texas coastline, and most are generally tolerant of salinity 

33 and water temperature fluctuations (Barbour et al. 1999; Ross 2001; STPNOC 2010d).

34 2.2.6.3 Transmission Lines

35 Power generated from STP during the proposed license renewal term would be transmitted 

36 using existing transmission line corridors. The transmission corridors pass through forested,

37 agricultural, and grasslands typical of the Texas coastal prairie (STPNOC 2010b). The water 

38 bodies crossed by the transmission corridors include small rivers, small streams, agricultural 

39 ponds, drainage areas, and wetlands (NRC 1975). The NRC staff is not aware of any aquatic 

40 surveys conducted along these corridors. The staff’s review of the terrain along the Hillje 

41 transmission line during a pre-application site visit for the proposed STP, Units 3 and 4, did not 

42 indicate any notable aquatic features within that region of the corridor (NRC 2008a). Observed 

43 water bodies included wetlands and small ponds. Aquatic species in the water bodies along the 

44 transmission corridors are likely similar to those communities typically found along the coastal 

45 plain and are likely tolerant to temporary changes in water quality (NRC 2011b; 

46 STPNOC 2010d).
Affected Environment 

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1 2.2.7 Terrestrial Resources

2 STP Ecoregion. Beginning in the 1980s, the USGS, EPA, the Commission for Environmental 

3 Cooperation, and various other Federal agencies and interagency groups have begun 

4 delineating North American ecoregions to provide a common geographical framework by which 

5 to assess and manage the environment. Ecoregions are divided into Levels I through IV; Level I 

6 encompasses large areas of land and is the broadest category, while Level IV is the most 

7 specific. Ecoregions are delineated by many factors to include location, climate, vegetation, 

8 hydrology, terrain, wildlife, and land use. The STP site lies within the following Level I through 

9 IV ecoregions:

10 • Level I: Great Plains, 

11 • Level II: Texas–Louisiana Coastal Plains, 

12 • Level III: Western Gulf Coastal Plain, and

13 • Level IV: Floodplains and Low Terraces. 

14 The Great Plains cover the majority of the midwestern states and are broadly characterized by a 

15 subhumid to semiarid climate, shortgrass and tallgrass prairie, and little topographic relief 

16 (EOE 2008). Within the Great Plains, the Texas-Louisiana Coastal Plains contain flat coastal 

17 plains, barrier islands, dunes, beaches, bays estuaries, and tidal marshes (Wiken et al. 2011). 

18 Historically, tallgrass prairie dominated the region. Within these coastal plains, STP lies within 

19 the floodplains and low terraces of the Western Gulf Coastal Plain, a 50- to 90-mi (80- to 

20 140-km) wide strip of flat land adjacent to the Gulf of Mexico (Griffith et al. 2007). The Western 

21 Gulf Coastal Plain comprises 1,743 ac (705 ha), with an elevation range of 5 to 200 ft (2 to 

22 60 m) above MSL (Griffith et al. 2007). The terrain is relatively flat, and grasslands dominate 

23 undeveloped areas. Inland regions contain some forested land and savannah lies inland, but 

24 the majority of this ecoregion is used as cropland for rice, cotton, and soybeans (Griffith et 

25 al. 2007). Other natural features include sloughs, natural levees, and alluvial terraces, as well 

26 as low gradient streams.

27 Natural habitats include deciduous bottomland forest and swamps. Maintained lands include 

28 cropland and pastureland. Common bottomland tree species include pecan (Carya illinoensis), 

29 water oak (Quercus nigra), southern live oak (Q. virginiana), and elm (Ulmus spp.) (Griffith et 

30 al. 2007). Baldcypress (Taxodium distichum), black hickory (C. texana), post oak (Q. stellata) 

31 and winged elm (U. alata) also grow in this region but are not as common (Griffith et al. 2007). 

32 Coastal marshes contain cordgrass (Spartina spp.), saltgrass (Distichlis spicata), needlerush 

33 (Juncus spp.), and saltmarsh bulrush (Scirpus paludosus) (Wiken et al. 2011). Common wildlife 

34 species include white-tailed deer (Odocoileus virginianus), ocelots (Leopardus pardalis), 

35 jaguarondi (Puma yagouaround), coyote (Canis latrans), ringtail cat (Bassariscus astutus), 

36 armadillo (Asypus novemcinctus), peccary (Pecari tajacu), swamp rabbit (Sylvilagus aquaticus), 

37 American alligator (Alligator mississippiensis), ferruginous pygmy-owl (Glaucidium brasilianum), 

38 green jay (Cyanocorax yncas), Altamira oriole (Icterus gularis), Attwater’s prairie-chicken 

39 (Tympanuchus cupido attwater), whooping cranes (Grus americana), and various species of 

40 ducks and geese (Wiken et al. 2011).

41 STP Site. The STP site occupies about 12,220 ac (4,950 ha) immediately west of the Colorado 

42 River and approximately 10 mi (16 km) from the river’s confluence with Matagorda Bay 

43 (STPNOC 2010b). Of that 12,220 ac (4,950 ha), the MCR occupies 7,000 ac; the STP 

44 buildings, warehouses, and infrastructure occupy about 300 ac (120 ha); and the ECP occupies 

45 46 ac (19 ha). The remaining land is undeveloped and includes bottomland, agricultural and 

46 pastureland, wetlands, mixed grasslands, and shrub scrub. ENSR conducted an ecological 
Affected Environment

2-39

1 survey of the STP site between 2006 and 2008. The NRC staff derived the majority of the 

2 information presented in this section from this assessment.

3 Along the Colorado River, on the eastern boundary of the STP site, lies about 1,176 ac (476 ha)

4 of bottomland forested habitat that contains a mixture of trees, shrubs, and grasses. Dominant 

5 tree species include sugarberry (Celtis laevigata), pecan, cottonwood (Populus spp.), water oak, 

6 southern live oak, American elm (Ulmus americana), willow (Salix spp.), and Chinese tallow 

7 (Sapium sebifera). Common shrub species include yaupon (Ilex vomitoria), Chinese privet 

8 (Ligustrum sinense), McCartney rose (Rosa meizeli), and American beautyberry (Callicarpa 

9 americana). Grassy areas contain woodoats (Chasmanthium latifolium), carpet grass 

10 (Axonopus affinis), crab grass (Digitaria spp.), broomsedge, and Bermuda grass (Cynodon 

11 dactylon). Another 53-ac (21-ha) forested area lies on the STP site north of the heavy haul 

12 road. The dominant species are the same as in the larger bottomland area (ENSR 2008b). 

13 Within the west and north of the developed portion of the site lies 976 ac (395 ha) of scrub 

14 shrub. Sea-myrtle (Baccharis halimifolia), goldenrod (Solidago spp.), ragweed (Ambrosia spp.), 

15 aster (Aster spp.), southern dewberry (Rubus trivialis), peppervine (Ampelopsis arborea), and 

16 sumpweed (Iva annua) are the most common vegetation (ENSR 2008b). 

17 About 486 ac (197 ha) of the site is mixed grasslands, some of which STPNOC regularly mows 

18 or maintains. Common grass species in these areas include angleton bluestem (Dichanthium 

19 aristatum), King Ranch bluestem (Bothriochloa ischaemum var. songarica), and bristle grass 

20 (Setaria spp.) (ENSR 2008b). 

21 Many wetlands exist on the site, some of which the USACE has determined to be jurisdictional 

22 wetlands. The non-jurisdictional wetlands include Kelly Lake and a 110-ac (45-ha) managed 

23 wetland along the northern portion of the site.

24 Kelly Lake is a 34-ac (14-ha) natural water body within the northeast corner of the site along the 

25 MCR embankment. It is fed by a small catchment area north of the lake. At least two drainages 

26 flow into the lake, and one drainage flows south along the east site of the MCR embankment 

27 and exits the lake (NRC 2011b). Cattail (Typha spp.) and arrowhead (Sagittaria spp.) surround 

28 Kelly Lake (NRC 2011b).

29 The 110-ac (45-ha) managed wetland is part of the larger Texas Prairie Wetland Project, a 

30 series of at least 35,000 ac (14,100 ha) of wetlands along the Gulf coasts that have been set 

31 aside or restored through a partnership with Ducks Unlimited, the Texas Parks and Wildlife 

32 Department, the U.S. Fish and Wildlife Service, the U.S. Department of Agriculture, and private 

33 landowners (Ducks Unlimited 2006). This wetland provides forage and wintering habitat for 

34 waterfowl, wading birds, and shorebirds (STPNOC 2010b). Houston Lighting and Power 

35 Company (HPLC), on behalf of STP, signed an agreement in October 1996 with Ducks 

36 Unlimited to manage and restore or enhance this portion of the STP property as part of the 

37 Texas Prairie Wetlands Project (Ducks Unlimited and HPLC 1996). As part of the agreement, 

38 HPLC committed to developing and managing the 110 ac (45 ha) to provide seasonal or 

39 semi-permanent wetland habitat for wintering migratory birds and other wetland-dependent 

40 wildlife (Ducks Unlimited and HPLC 1996). HPLC also built multiple impoundments to create 

41 foraging habitat (Ducks Unlimited and HPLC 1996).

42 The jurisdictional wetlands include 29 small wetlands within the northern portion of the site, 

43 most of which are ditches or depression wetlands (USACE 2009). The largest delineated 

44 wetland is 3.78 ac (1.53 ha), and 16 of the delineated wetlands are less than 0.5 ac (0.2 ha)

45 (ENSR 2008b). In total, jurisdictional wetlands cover 17.6 ac (7.1 ha) (USACE 2009). 

46 Dominant wetland vegetation includes spikerush (Eleocharis spp.), cattail (Typha spp.), water 

47 hyssop (Bacopa monnieri), knotgrass (Polygonum spp.), bushy bluestem (Andropogon 
Affected Environment 

2-40

1 glomeratus), sea-myrtle, and rattlebox (Crotalaria spp.) (ENSR 2008b). Additionally, the 

2 USACE has designated 24,639 linear feet (7,510 linear meters) of non-wetland areas as 

3 jurisdictional waters.

4 The most common wildlife on the site include white-tailed deer, rabbit (Silvilgus spp.), squirrel 

5 (Sciurus spp.), and feral hogs (Sus scrofa) (STPNOC 2010b). Cardinals (Cardinalis cardinalis), 

6 mourning doves (Zenaida macroura), bobwhite quail (Colinus virginianus), red-winged 

7 blackbirds (Agelaius phoeniceus), grackles (Quiscalus spp.), black vultures (Coragyps atratus), 

8 and turkey vultures (Cathartes aura) are the most common birds. Wading birds, such as great 

9 blue heron (Ardea herodias), great egret (Ardea alba), roseate spoonbill (Ajaia ajaja), white ibis 

10 (Eudocimus albus), and little blue heron (Egretta caerulea), are common near Kelly Lake, the 

11 MCR, and other water features (STPNOC 2010b). American alligators, discussed in more detail 

12 in Section 2.2.7, regularly inhabit the site. Other common reptiles include the copperhead 

13 snake (Agkistrodon contortrix contortrix), cottonmouth snake (A. piscivorus), eastern hog-nosed 

14 snake (Heterodon platirhinos), eastern racer (Coluber constrictor), corn snake (Elaphe guttata), 

15 eastern rat snake (E. obsoleta), diamondback watersnake (Nerodia rhombifer rhombifer), 

16 eastern box turtle (Terrapene carolina), ornate box turtle (T. ornata), snapping turtle (Chelydra 

17 serpentina), red-eared pond slider (Trachemys scripta elegans), green anole (Anolis 

18 carolinensis), and five-lined skink (Eumeces fasciatus) (NRC 2011b).

19 Each year, Matagorda County hosts a Christmas Bird Count, a volunteer bird count organized 

20 by the Audubon Society that runs from December 14 through January 5 of each year. The 

21 count centers on Mad Island and encompasses about 113,000 ac (45,700 ha) within a 15-mi 

22 (24-km) radius. Because the STP site lies near the southern terminus of the Central Flyway, a 

23 great diversity of birds inhabit or pass through the site and surrounding region, and the region 

24 provides important stopover and wintering habitat for migrating birds. During the 2010 to 2011 

25 bird count, participants recorded 231 different bird species (Audubon 2011). Within the past 

26 5 years of bird count data, red-winged blackbirds (Agelaius phoeniceus) and brown-headed 

27 cowbirds (Molothrus ater) accounted for the overwhelming majority (70 and 19 percent, 

28 respectively) of recorded observations. Figure 2–5 identifies the most commonly observed 

29 species in the past 5 years of Christmas Bird Counts. The birds in this figure were of the top 

30 10 most commonly recorded species for at least 2 years out of the past five Christmas Bird 

31 Counts. In addition to the bird species in Figure 2–5, six additional species appeared in the top 

32 10 recorded species for only one data year. Table 2–6 lists these species and the year and 

33 number of each.

34 Table 2–6. Birds Observed in High Numbers for One Christmas Count Year, 

35 2007 through 2011

Species

Year Recorded Within Top 

10 Most Common Species

# of Individuals 

Recorded

American white pelican 2009–2010 1,700

blackbird spp. 2010–2011 5,115

lesser scaup 2010–2011 85,438

redhead 2008–2009 15,005

Ross’s goose 2009–2010 2,537

sandhill crane 2008–2009 10,000

Source: Audubon 2011
2-41

Figure 2–5. Most Commonly Recorded Christmas Bird Count Species, 2007 through 2011 (Aud1 

American 

coot

American 

greenwinged 

teal

American 

robin

boattailed 

grackle

Brewer's 

blackbird

Brownheaded 

Cowbird

common 

grackle

greattailed 

grackle

greater 

whitefronted 

goose

northern 

pintail

redwinged 

blackbird

2010-11 3994 3828 0 4340 0 20752 0 0 10419 0 317446 

2009-10 4315 0 0 11328 0 20626 0 0 2796 3965 62183 

2008-09 6400 0 0 23459 0 26100 5000 10700 0 6878 415000 

2007-08 0 10785 6006 0 5881 792077 93127 133443 0 5432 2561465 

2006-07 0 10785 6006 0 5881 792077 93127 133443 0 5432 2561465 

0 

80000

60000

40000

20000

140000

120000

100000

Number of Individuals Observed
Affected Environment 

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1 In addition to the data available from the Christmas Bird Counts, ENSR conducted a bird survey 

2 in 2006 and 2007 on the STP site as part of the STP, Units 3 and 4, COL application. 

3 Table 2–7 lists the bird species that ENSR observed on the STP site during this survey and the 

4 types of habitats or areas of the site in which each was associated.

5 Table 2–7. Birds Documented on the STP Site, 2007 through 2008

Species Common Name

Habitat Type or Area 

Observed

Trans-Gulf 

Migrant(a)

Agaelaius phoeniceus red-winged blackbird grassland/scrub-shrub

Anhinga anhinga anhinga MCR

Ardea herodias great blue heron wetland/MCR

Bubulcus ibis cattle egret grassland/wetlands

Buteo jamaicensis red-tailed hawk grassland/scrub-shrub

Buteo lineatus red-shouldered grassland/scrub-shrub

Caracara cheriway crested caracara grassland

Cathartes aura turkey vulture grassland/scrubshrub/developed

Charadrius vociferus killdeer grassland/developed

Circus cyaneus northern harrier grassland/scrub-shrub

Colinus virginianus northern bobwhite grassland/scrub-shrub

Coragyps atratus black vulture grassland/scrubshrub/developed

Corvus brachyrhynchos American crow grassland/scrub-shrub

Cyanocitta cristata bluejay scrub-shrub

Dendrocygna bicolor fulvous whistling-duck wetland

Egretta caerulea little blue heron wetlands

Egretta thula snowy egret wetland/MCR

Egretta tricolor tri-colored heron wetland/MCR

Eudocimus albus white ibis grassland/wetlands

Fulica americana American coot wetlands

Gelochelidon nilotica gull-billed tern MCR

Geothlypis trichas common yellowthroat scrub-shrub x

Haliaeetus leucocephalus bald eagle river shoreline

Hirundo rustica barn swallow grassland/developed x

Leucophaeus atricilla laughing gull MCR/developed

Megaceryle alcyon belted kingfisher wetlands x
Affected Environment

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Species Common Name

Habitat Type or Area 

Observed

Trans-Gulf 

Migrant(a)

Mimus polyglottos northern mockingbird MCR/developed

Molothrus ater brown-headed cowbird grassland/scrubshrub/developed

Nycticorax nycticorax black-crowned night-heron grassland/scrub-shrub

Pandion haliaetus osprey wetland

Pelecanus erythrorhynchos American white pelican MCR

Pelecanus occidentalis brown pelican MCR

Petrochelidon pyrrhonota cliff swallow MCR x 

Platalea ajaja roseate spoonbill MCR

Progne subis purple martin grassland/scrubshrub/developed x 

Quiscalus major boat-tailed grackle grassland/scrubshrub/developed

Sturnella magna eastern meadowlark grassland/scrub-shrub

Turdus migratorius American robin grassland

Tyrannus forficatus scissor-tailed flycatcher grassland/scrub-shrub x

Zenaida macroura mourning dove grassland/developed

(a) Birds that cross the Gulf of Mexico from the Yucatan Peninsula to the Gulf coasts 

Source: ENSR 2008b; NRC 2011b

1 Waterbirds nest on the ends “Y” dike that directs water flow in the MCR. STPNOC first 

2 observed nesting on the MCR dikes in 1986 (STPNOC 2010d). The dominate nesting species 

3 include laughing gulls (Leucophaeus atricilla) (53 percent) and gull-billed terns (Gelochelidon 

4 nilotica) (31 percent), which account for a collective 84 percent of the 1,200 to 1,600 nests per 

5 year (STPNOC 2010d). Seven additional bird species nest on the dikes with typically fewer 

6 than 100 nests each (STPNOC 2010d).

7 Transmission Line Corridors. The transmission lines traverse mostly agricultural lands, as well 

8 as forests and grasslands in 12 counties. The habitat is typical of that described previously 

9 under “STP ecoregion.” The corridors do not cross any designated critical habitat, Federal or 

10 State parks, wildlife preserves, refuges, or sanctuaries (STPNOC 2010b).

11 Parks and Wildlife Preserves. Many parks and wildlife preserves provide valuable terrestrial 

12 habitat to native migrating birds. Those in the vicinity of STP are discussed briefly below.

13 The Brazos Bend State Park is a 5,000-ac (2,000-ha) park located about 35 mi (56 km) 

14 northeast of the STP site. The Texas Parks and Wildlife Department established this park in 

15 1976. Natural habitats include the Brazos River floodplains, upland coastal prairie, bottomland 

16 hardwood forest, seasonal freshwater marshes, and oxbow lakes (TPWD 2011a). The park is 

17 home to over 300 species of birds, 21 species of reptiles and amphibians, 17 species of 

18 mammals, 39 species of dragonflies, and 500 species of plants (TPWD 2011a).
Affected Environment 

2-44

1 The Mad Island Marsh Preserve lies about 4 mi (6 km) southwest of STP. This preserve is 

2 situated on West Matagorda Bay around Mad Island Lake and encompasses a total of 7,063 ac 

3 (2,860 ha) (GCBO 2011). The preserve includes coastal prairie, freshwater wetlands, tidal 

4 saltwater wetlands, and shrubland. The Gulf Coast Bird Observatory has recorded over 

5 300 species of birds within the preserve, including sandhill cranes (Grus canadensis), cinnamon 

6 teal (Anas cyanoptera), blue-winged teal (A. discors), northern pintail (A. acuta), Canada goose 

7 (Branta canadensis), and snow goose (Chen caerulescens) (GCBO 2011). Many habitat 

8 restoration and enhancement projects within this preserve—including prescribed burns, erosion 

9 control, and rotational cattle grazing in limited areas—continue to enhance the value of the 

10 habitat.

11 The Texas Parks and Wildlife Department manages the 7,200-ac (2,900-ha) Mad Island Wildlife 

12 Management Area, which lies about 3 mi (5 km) south of STP (TPWD 2011d). The State of 

13 Texas purchased this parcel of land to preserve coastal wetland habitat for wintering waterfowl. 

14 The management area contains brackish marsh and coastal prairies and provides habitat for a 

15 wide variety of wildlife

16 The U.S. Fish and Wildlife Service (FWS) manages the Big Boggy National Wildlife Refuge, 

17 which lies about 10 mi (16 km) southwest of STP (FWS 2011c). Figure 2–6 and Figure 2–7

18 show the STP 50-mi (80-km) radius map (STPNOC 2010b) and STP 6-mi (10-km) radius map 

19 (STPNOC 2010b), respectively. The FWS established this 4,526-ac (1,832-ha) refuge in 1983 

20 to protect saltmarsh habitat for migratory birds. Within the refuge, Dressing Point Island in East 

21 Matagorda Bay is an important rookery for brown pelicans, roseate spoonbills, white ibis, snowy 

22 egrets, and other colonial nesting birds.
Affected Environment

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1 Figure 2–6. STP 50-mi (80-km) Radius Map (STPNOC 2010b) 
Affected Environment 

2-46

1 Figure 2–7. STP 6-mi (10-km) Radius Map (STPNOC 2010b) 

 2 
Affected Environment

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1 2.2.8 Protected Species and Habitats

2 This section discusses species and habitats that are:

3 • Federally protected under the Endangered Species Act (ESA) of 1973, as 

4 amended;

5 • designated as a species of concern under the National Marine Fisheries 

6 Service (NMFS)’s Species of Concern Program; 

7 • Federally protected under the Bald and Golden Eagles Protection Act of 

8 1940, as amended;

9 • Federally protected under the Migratory Bird Treaty Act of 1918 (MBTA), as 

10 amended;

11 • Federally protected under the Magnuson–Stevens Fishery Conservation and 

12 Management Act (MSA), as amended;

13 • Federally protected under the Marine Mammal Protection Act (MMPA) of 

14 1972, as amended; or

15 • State-protected under Title 5, Wildlife and Plant Conservation, Chapter 68, 

16 Endangered Species, and Chapter 88, Endangered Plants, of the State of 

17 Texas’s Statutes.

18 2.2.8.1 Species and Habitats Protected Under the Endangered Species Act

19 The FWS and the NMFS jointly administer the ESA. The FWS manages the protection of and 

20 recovery effort for listed terrestrial and freshwater species, while the NMFS manages the 

21 protection of and recovery effort for listed marine and anadromous species. Table 2–8 identifies 

22 species under the FWS and NMFS’s jurisdiction that occur in Matagorda County, in which STP 

23 is located, or within one of the 12 counties through which the transmission line corridors 

24 traverse.

25 Table 2–8. Species Listed Under the ESA

Status(a) Potential Occurrence(b)

Species Common Name Federal State Matagorda 

County

T-line 

Counties

Amphibians

Bufo houstonensis Houston toad E E x

Eurycea nana San Marcos salamander T T x 

Typhlomolge rathbuni Texas blind salamander E E x 

Arachnids

Cicurina baronia Robber Baron Cave meshweaver E - x 

Cicurina madla Madla Cave meshweaver E - x 

Cicurina venii braken bat cave meshweaver E - x

Cicurina vespera Government Canyon bat cave 

meshweaver

E - x
Affected Environment 

2-48

Status(a) Potential Occurrence(b)

Species Common Name Federal State Matagorda 

County

T-line 

Counties

Neoleptoneta microps Government Canyon bat cave 

spider

E - x

Texella cokendolpheri Cokendolpher cave harvestman E - x

Birds

Charadrius melodus piping plover T T x x

Dendroica chrysoparia golden-cheeked warbler E E x

Falco femoralis 

septentrionalis

northern aplomado falcon E E x x

Grus americana whooping crane E E x x 

Tympanuchus cupido 

attwateri

Attwater’s greater prairie-chicken E E x 

Vireo atricapilla black-capped vireo E E x

Crustaceans

stygobromus pecki Peck’s cave amphipod E - x

Fish

Etheostoma fonticola fountain darter E E x

Gambusia georgei San Marcos gambusia E E x

Pristis pectinata smalltooth sawfish E E x

Pristis pristis largetooth sawfish E - x

Insects

Batrisodes venyivi helotes mold beetle E - x

Heterelmis comalensis Comal Springs riffle beetle E - x

Rhadine exilis unnamed beetle E - x

Rhadine infernalis unnamed beetle E - x

Stygoparnus comalensis Comal Springs dryopid beetle E - x

Mammals

Balaenoptera borealis sei whale E - x 

Balaenoptera musculus blue whale E - x 

Balaenoptera physalus finback whale E E x 

Herpailurus yaguarondi 

cacomitli

Gulf coast jaguarundi E E x 

Leopardus pardalis ocelot E E x x

Megaptera novaeangliae humpback whale E E x
Affected Environment

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Status(a) Potential Occurrence(b)

Species Common Name Federal State Matagorda 

County

T-line 

Counties

Physeter macrocephalus sperm whale E - x

Trichechus manatus West Indian manatee E E x

Plants

Spiranthes parksii Navasota ladies’ tresses E E x

Spiranthes parksii Texas wild rice E E x

Reptiles

Alligator mississipiensis(c) American alligator T(SA) - x x

Caretta caretta loggerhead sea turtle T T x

Chelonia mydas green sea turtle T T x

Dermochelys coriacea leatherback sea turtle E E x

Eretmochelys imbricata hawksbill sea turtle E E x

Lepidochelys kempii Kemp’s ridley sea turtle E E x

(a) E=endangered; P=proposed; T=threatened; T(SA)=threatened due to similarity of appearance; - = not listed

(b) The STP site is located in Matagorda County. The transmission lines associated with the STP site traverse 

Matagorda County as well as Bexar, Brazoria, Colorado, DeWitt, Fayette, Gonzales, Guadalupe, Jackson, Lavaca, 

Wharton, and Wilson Counties.

(c) The American alligator is designated as threatened due to its similarity of appearance with the American crocodile 

(Crocodylus acutus). 

Sources: FWS 2011a, 2011b; NMFS 2011c; NRC 2011b; STPNOC 2010b; TPWD 2011c, 2011f

1 STPNOC has observed one Federally listed species on the STP site since the facility began 

2 operating—the American alligator (Alligator mississippiensis) (STPNOC 2010b). The FWS has 

3 designated the American alligator as “threatened due [to] similarity of appearance” with the 

4 threatened American crocodile (Crocodylus acutus). Additionally, two delisted species occur on 

5 the site—the bald eagle (Haliaeetus leucocephalus) and the brown pelican (Pelecanus 

6 occidentalis). This section also discusses in more detail the piping plover (Charadrius 

7 melodus), whooping crane (Grus americana), ocelot (Leopardus pardalis), and Gulf coast 

8 jagaurundi (Herpailurus yaguarondi cacomitli). None of these four species occur on the STP 

9 site (STPNOC 2010b), but the FWS has designated piping plover as critical habitat along 

10 Matagorda Bay about 7 mi (11 km) south of the STP site. Additionally, the FWS identified the 

11 whooping crane, ocelot, and Gulf coast jagaurundi as species of interest in its correspondence 

12 with the NRC (FWS 2011b). The NRC staff did not identify any proposed species or proposed 

13 critical habitat in the vicinity of the STP site or along the transmission line corridors during its 

14 environmental review.

15 American Alligator. The FWS listed the American alligator in 1967 under the Endangered 

16 Species Preservation Act of 1966, the predecessor regulation to the ESA. Following 

17 reclassification actions in several states, the FWS declared the species fully recovered in 1987 

18 and reclassified it as “threatened due to similarity of appearance” to the American crocodile 

19 (Crocodylus acutus) throughout the remainder of the species’ range (52 FR 21059). American 

20 alligators inhabit coastal swamps from North Carolina southward and around the Gulf of Mexico 
Affected Environment 

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1 as far west as Texas (Audubon 2004). They also inhabit coastal flatlands as far north as 

2 Arkansas (Audubon 2004).

3 Alligators inhabit the wetlands on the STP site as well as the MCR (STPNOC 2010b). During a 

4 1987 to 1988 ecological study, Baker and Greene (1989) observed small numbers of alligators 

5 near Kelly Lake, the south drainage canal, Little Robins Slough, and the various dikes 

6 associated with the MCR. In 2007 through 2008, ENSR (2008b) did not observe any Federally 

7 listed species during a threatened and endangered species survey. However, ENSR conducted 

8 this survey during the winter months, during which time alligators are less active and likely seek 

9 refuge in swamps and wetlands near the STP site that provide more shelter.

10 Piping Plover and Designated Critical Habitat. Piping plover is a Federally and State-listed 

11 threatened species that winters along the Gulf of Mexico coast. A recent study of the taxonomy 

12 of the species (Miller et al. 2009) confirmed genetic uniqueness of only two subspecies—

13 Atlantic (C.m. melodus) and Interior (C.m. circumcinctus). The FWS recognizes three distinct 

14 population segments in its ESA rulemakings—the Atlantic Coast, the Great Lakes, and the 

15 Northern Great Plains populations (FWS 2009). The Atlantic Coast population is C.m. melodus, 

16 while the Great Lakes and Northern Great Plains populations are C.m. circumcinctus. 

17 The Texas coast provides wintering habitat for all three distinct population segments between 

18 September and March. Piping plovers inhabit wide, flat, open, sandy beaches and nest in small 

19 creeks and wetlands (FWS 2011d) such as those found along the Texas coast. 

20 STPNOC (2010b) reported that it has not observed the species on the STP site; however, the 

21 species inhabits the nearby shoreline of Matagorda Bay and the Gulf of Mexico.

22 STP is in close proximity to four units of designated piping plover critical habitat. The closest 

23 critical habitat unit is TX-26, Colorado River Diversion Delta, which consists of 13 ac (5 ha) that 

24 follow the shore of the northeast corner of West Matagorda Bay from Culver Cut to Dog Island 

25 Reef (66 FR 36038). This unit is about 7 mi (11 km) south of the STP site boundary. It includes 

26 roosting areas and is infrequently inundated by seasonal winds. The other three units are 

27 (66 FR 36038):

28 (1) TX-23, West Matagorda Peninsular Beach—769 ac (311 ha) of Gulf of Mexico 

29 shoreline from the Matagorda Ship Channel jetties to the old Colorado River channel,

30 (2) TX-25, West Matagorda Bay and Eastern Peninsula Flats—575 ac (232 ha) following 

31 the bayside of Matagorda Peninsula from Maverick Slough southwest for 3 mi

32 (5 km), and

33 (3) TX-27, East Matagorda Bay and Matagorda Peninsular Beach West—728 ac 

34 (295 ha) of Gulf of Mexico shoreline from the mouth of the Colorado River northeast 

35 along the peninsula for 14 mi (23 km).

36 Within these units, only the areas that contain “primary constituent elements” (the physical and 

37 biological landscape features that a species requires to survive and reproduce) are considered 

38 critical habitat (FWS 2000). Therefore, buildings, marinas, parking lots, and other developed 

39 areas do not constitute critical habitat.

40 Other Federally Listed Species. In addition to the species discussed above, in its 

41 correspondence with the NRC, the FWS (2011b) provided information and recommendations 

42 concerning three additional Federally listed species—the whooping crane, the ocelot, and the 

43 Gulf coast jaguarundi.

44 The whooping crane migrates to the Texas coast between late October and mid-November and 

45 generally stays through late March to mid-April before returning to breeding grounds in Canada 

46 (FWS 2011b). Whooping cranes fly relatively high when migrating (1,000 to 6,000 ft (300 to 
Affected Environment

2-51

1 1,800 m) in altitude) but will fly lower when searching for stopover habitat (FWS 2011b). The 

2 species is present in Matagorda County as well as all counties through which the transmission 

3 lines traverse. However, the whooping crane has not been observed on the STP site and is 

4 unlikely to use the inland habitat on the site (NRC 2011b).

5 The ocelot and the Gulf coast jaguarundi inhabit dense, low brush. The ocelot requires 70 to 

6 90 percent canopy cover, while the Gulf coast jaguarundi tolerates more open habitat 

7 (FWS 2011b). The ocelot historically occurred throughout southern Texas but is now restricted 

8 to southern Edwards Plateau and along the Coastal Plain (TPWD 2011e). The Gulf coast 

9 jaguarundi’s available habitat has also diminished, and the cat now only occurs in the Rio 

10 Grande Valley within Cameron and Willacy Counties (TPWD 2011b). Neither of these species 

11 occurs on the STP site nor are they likely to occur along the transmission line corridors since 

12 the transmission lines pass through mostly agricultural lands. Additionally, since the 

13 transmission line corridors have been maintained for early successional habitat since their 

14 construction, they do not provide suitable habitat for either the ocelot or Gulf coast jaguarundi.

15 For the remaining Federally listed species that appear in Table 2–8, the FWS (2011b) did not 

16 note any of the remaining species under its jurisdiction either to occur on the STP site or to 

17 potentially be affected by the proposed license renewal. Though some of the marine species 

18 under NMFS’s jurisdiction listed in Table 2–8 may occur in Matagorda Bay, none of these 

19 species would occur in the Colorado River due to their habitat requirements. Additionally, 

20 STPNOC (2010b) did not report occurrences of any of these species on the STP site. 

21 Therefore, these species are not discussed in detail.

22 2.2.8.2 Species Designated as NMFS Species of Concern

23 The NMFS established a Species of Concern Program and species of concern list in 2004 to 

24 distinguish between candidate species under the ESA and other species that the NMFS 

25 identifies as potentially at risk but for which no ESA listing action has been initiated 

26 (69 FR 19975). The NMFS defines “species of concern” as “those species about which the 

27 NMFS has some concerns regarding threats to continued existence and population status, but 

28 for which insufficient information is available to initiate listing actions under the ESA 

29 (NMFS 2011d).” 

30 The term “species of concern” does not appear in either the ESA or its implementing 

31 regulations; therefore, it does not carry any procedural or substantive protections under the 

32 ESA. Only the NMFS, and not the FWS, maintains a Species of Concern Program and species 

33 of concern list. Species of concern in the vicinity of STP appear in Table 2–9. 

34 Table 2–9. NMFS Species of Concern

Species Common Name Area of Concern(a) Habitat

Anthrozoa

Oculina varicosa ivory tree coral Atlantic Ocean—West 

Indies, Bermuda, North 

Carolina, Florida, Gulf 

of Mexico, Caribbean

inhabit shallow subtidal waters, 

limestone rubble and ledges, and 

soft-bottom sloping habitats from 

2–152 m in depth

Fish

Carcharhinus obscurus dusky shark Atlantic Ocean; Gulf of 

Mexico; Pacific

surf zone to waters 400 m deep; 

not commonly found in estuaries 

due to salinity requirements
Affected Environment 

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Species Common Name Area of Concern(a) Habitat

Carcharias taurus sand tiger shark Atlantic Ocean; Gulf of 

Mexico

surf zone to depths of 25 m; 

shallow bays; around coral reefs

Epinephelus 

drummondhayi

speckled hind Atlantic Ocean—North 

Carolina to Gulf of 

Mexico

offshore rocky bottoms with 

depths of 25–183 m; most 

common between 60–120 m 

Epinephelus nigritus warsaw grouper Atlantic Ocean—Maine 

southward to Gulf of 

Mexico

continental shelf reefs in waters 

76–219 m deep

Fundulus jenkinsi saltmarsh topminnow Atlantic Ocean—TX, 

LA, MS, AL, FL

small, tidal marshes with salinity 

of 1–4 ppt

(a) Areas of concern are specified by the NMFS species of concern list (NMFS 2011e). 

Sources: 75 FR 25174; Aronson et al. 2008; Musick et al. 2007; NMFS 2011c; NRC 2011b; Pollard and Smith 2005; 

Wai and Huntsman 2006a, 2006b; WEG 2010

1 Ivory Tree Coral. The ivory tree coral (Oculina varicosa) inhabits marine waters from Cape 

2 Hatteras, North Carolina, through the Gulf of Mexico and the Caribbean. However, it is only an 

3 NMFS species of concern along the eastern U.S. coast from North Carolina through Florida. 

4 Most of the species’ population is concentrated off east-central Florida, where it occurs in its 

5 deep-water form and creates thicket-type structures. The species may occur in Matagorda Bay 

6 in its shallow form, in which the coral forms a symbiotic relationship with zooxanthellae. The 

7 shallow form reproduces in July and August via broadcast spawning. Ivory tree coral 

8 suspension feeds on planktonic organisms and provides refuge for over 300 species of 

9 invertebrates. (NMFS 2010d) 

10 Sand Tiger Shark. The sand tiger shark (Carcharias taurus) is a species of concern in the 

11 western Atlantic and northern Gulf of Mexico, though the species is globally distributed in all 

12 warm and temperate seas and oceans except the eastern Pacific. Tiger sharks mature at about 

13 6 ft (1.9 m) in length and reach up to 10.4 ft (3.18 m) in length. Individuals are generally solitary 

14 but occur in schools for feeding, courtship, mating, and birthing. Females give birth to one or 

15 two pups every other year. Sand tiger sharks migrate toward the equator in fall and winter and 

16 move poleward during the summer. They prey on bony fishes, small sharks, rays, squid, crabs, 

17 and lobster. (NMFS 2010e) 

18 Saltmarsh Topminnow. The saltmarsh topminnow (Fundulus jenkinsi) is a species of concern in 

19 the coastal waters of Texas, Louisiana, Mississippi, Alabama, and Florida. Saltmarsh 

20 topminnow occur in estuaries, coastal salt marshes, and back water sloughs and tolerate water 

21 with salinities of 1 to 20 ppt (NMFS 2009). Females grow up to 60 mm (2.4 in.) in length and 

22 males grow to 50 mm (1.9 in.) (NMFS 2009). The NMFS (2009) reports that no information on 

23 reproductive behavior or diet is available for this species.

24 Other Species of Concern. The dusky shark (Carcharhinus obscurus), speckled hind 

25 (Epinephelus drummondhayi), and warsaw grouper (Epinephelus nigritus) are unlikely to occur 

26 in Matagorda Bay due to their habitat requirements.

27 In addition to the species already discussed, the NMFS (2011c) listed the night shark as a 

28 species of concern occurring in the vicinity of STP. However, the NMFS (2010c) removed the 

29 night shark from its species of concern list in 2010. It most often occurs in waters 50 to 100 m 

30 (160 to 330 ft) deep, but it can inhabit waters as deep as 600 m (2,000 ft) (Santana et al. 2006). 

31 Because of its depth requirements, the night shark is unlikely to occur in Matagorda Bay.
Affected Environment

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1 2.2.8.3 Species Protected Under the Bald and Golden Eagles Protection Act

2 The Bald and Golden Eagle Protection Act prohibits anyone from taking bald eagles (Haliaeetus 

3 leucocephalus) or golden eagles (Aquila chrysaetos), including their nests or eggs, without an 

4 FWS-issued permit. The term “take” in the Act is defined as to “pursue, shoot, shoot at, poison, 

5 wound, kill, capture, trap, collect, molest, or disturb” (50 CFR 22.3). “Disturb” means to take 

6 action that causes injury to an eagle; decreases its productivity by interfering with breeding, 

7 feeding, or sheltering behavior; or results in nest abandonment (50 CFR 22.3).

8 Bald eagles are present year-round throughout Texas. Breeding populations primarily inhabit 

9 the eastern half of the State and the coastal counties from Rockport to Houston 

10 (Campbell 2003). During ecological surveys associated with the COL application for STP, 

11 Units 3 and 4, ENSR (2007) listed bald eagles as one of the bird species observed on the STP 

12 site. An active bald eagle nest lies near the site’s eastern boundary in remote woodlands along 

13 the Colorado River (NRC 2011b). STPNOC (2010c) first observed this nest site in 2004. A 

14 second bald eagle nest lies within 6 mi of the STP site (NRC 2011b).

15 2.2.8.4 Species Protected Under the Migratory Bird Treaty Act

16 The FWS administers the MBTA, which prohibits anyone from taking native migratory birds or 

17 their eggs, feathers, or nests. The MBTA definition of a “take” differs from that of the ESA and 

18 is defined as “to pursue, hunt, shoot, wound, kill, trap, capture, or collect, or any attempt to carry 

19 out these activities” (50 CFR 10.12). Unlike a take under the ESA, a take under the MBTA does 

20 not include habitat alteration or destruction. The MBTA protects 1,007 migratory bird species 

21 (75 FR 9282). Of these 1,007 species, the FWS allows for the legal hunting of 58 species as 

22 game birds (FWS undated). Within Texas, the Texas Parks and Wildlife Department manages 

23 migratory bird hunting seasons and associated licenses for ducks, geese, coot, rail, gallinules, 

24 snipe, woodcock, doves, and sandhill cranes. All Federally and State-listed bird species that 

25 appear in Table 2–8 and Table 2–11 are protected under the MBTA. MBTA-protected-bird 

26 species that commonly occur near the STP site are discussed in Section 2.2.6. Additionally, all 

27 U.S.-native bird species that belong to the families, groups, or species listed in 10 CFR 10.13 

28 are protected under the MBTA.

29 2.2.8.5 Species Protected Under the Marine Mammal Protection Act

30 The MMPA established a moratorium on the direct or indirect taking of all species of marine 

31 mammals in the U.S. The MMPA defines a “take” to mean “to hunt, harass, capture, or kill.” 

32 The NMFS (for whales, dolphins, porpoises, seals, and sea lions) and FWS (for walrus, 

33 manatees, otters, and polar bears) may issue take permits for takes that are incidental to 

34 commercial fishing, scientific research, and other nonfishing activities.

35 Under the MMPA, the NMFS and FWS manage marine mammals by identifying the “optimum 

36 sustainable population” level for each species. Those species whose populations have fallen 

37 below the optimum sustainable level are considered “depleted.” Within the Gulf of Mexico, 

38 29 marine mammals occur (NMFS 2011b; TMMSN 2011). Of these, only the bottlenose dolphin 

39 (Tursiops truncates) occurs within Matagorda Bay due to the bay’s shallow depth. Bottlenose 

40 dolphins inhabit pelagic waters along the continental shelf and may migrate into bays, estuaries, 

41 and river mouths (NMFS 2011a). Those bottlenose dolphins found in Matagorda Bay are part of 

42 the Northern Gulf of Mexico Bay, Sound, and Estuarine Stock. According to NMFS’s 2010 stock 

43 assessment (NMFS 2010a), the status of this stock is unknown because the most recent 

44 population estimates are eight or more years old, but this stock is not considered depleted. The 

45 NMFS estimates the larger Northern Gulf of Mexico Coastal stock to be 4,191 individuals as of 

46 2007 (NMFS 2011a).
Affected Environment 

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1 2.2.8.6 Species Protected Under the Magnuson–Stevens Act

2 The Gulf of Mexico Fishery Management Council (GMFMC) has designated the lower Colorado 

3 River, the GIWW, and Matagorda Bay as essential fish habitat (EFH) for many species in 

4 accordance with the MSA. These waters are collectively referred to as part of Ecoregion 5 in 

5 the GMFMC’s Final EIS for the Generic Essential Fish Habitat Amendment for Gulf of Mexico

6 fishery management plans (GMFMC 2004).

7 Table 2–10 lists those species with designated EFH within Ecoregion 5 and specifies which of 

8 those species’ life stages have the potential to occur in the vicinity of STP based on each 

9 stage’s life history requirements.

10 Table 2–10. Ecoregion 5 Species with Designated EFH

Species Common Name

Fishery 

Management Plan

EFH Life Stages 

in Ecoregion 5(a)

Life Stages in the 

Vicinity of STP(b)

Scomberomorus 

cavalla king mackerel coastal migratory 

pelagic all stages juveniles

Scomberomorus 

maculatus Spanish mackerel coastal migratory 

pelagic all stages all stages

Lutjanus griseus mangrove snapper reef fish all stages all stages

Sciaenops ocellatus red drum red drum all stages all stages

Farfantepenaeus 

aztecus brown shrimp shrimp all stages larvae, juveniles

Farfantepenaeus 

duorarum pink shrimp shrimp all stages larvae, juveniles

Litopenaeus setiferus white shrimp shrimp all stages larvae, juveniles

Menippe adina Gulf stone crab stone crab all stages all stages

(a) “All stages” indicates that egg, larvae, juvenile, and adult EFH are present.

(b) The species’ life stages that do not occur in the vicinity of STP were eliminated based on depth or salinity 

requirements or both, which are presented in GMFMC’s Final EIS for the Generic Essential Fish Habitat 

Amendment for Gulf of Mexico fishery management plans (GMFMC 2004). 

11 A brief discussion of each EFH species appears below. This section summarizes information 

12 on each species from the GMFMC’s Final EIS for the Generic Essential Fish Habitat 

13 Amendment for Gulf of Mexico fishery management plans (GMFMC 2004) unless otherwise 

14 noted.

15 King and Spanish Mackerel. King mackerel (Scomberomorus cavalla) and Spanish mackerel 

16 (Scomberomorus maculates) occur in the Gulf of Mexico. Concentrated populations of king 

17 mackerel occur in the coastal waters of South Florida and Louisiana, and the most concentrated 

18 population of Spanish mackerel is off the coast of Florida. Adults of both species generally 

19 inhabit reefs and coastal waters with salinity ranging from 32 to 36 ppt. Spanish mackerel 

20 prefer waters of up to 75 m (250 ft) and will occasionally inhabit estuaries. King mackerel 

21 inhabit waters up to 200 m (660 ft), though they most often occupy waters less than 80 m 

22 (260 ft). Adult king mackerel eat jacks, snappers, grunts, halfbeaks, penaeid shrimp, squid, 

23 and—less commonly—crustaceans and mollusks. Spanish mackerel eat clupeids, engraulids, 

24 carangids, and squid. Predators of both species include pelagic sharks, little tunny, and 

25 dolphin.
Affected Environment

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1 King mackerel spawn over the outer continental shelf from May to October, while Spanish 

2 mackerel spawn over the inner continental shelf. Both species’ eggs are pelagic and buoyant. 

3 King mackerel larvae inhabit the middle and outer continental shelf, while Spanish mackerel 

4 larvae move to the inner continental shelf. Larvae consume smaller larval fish such as 

5 carangids, clupeids, and engraulids. Young tuna and dolphins prey upon king mackerel larvae. 

6 Juveniles inhabit both offshore and estuarine waters and eat smaller fish and invertebrates. 

7 Little tunny, dolphin, and other pelagic fish prey on juveniles.

8 Mangrove Snapper. Larval, juvenile, and adult mangrove snapper (Lutjanus griseus) primarily 

9 occupy inshore habitats, such as estuaries and continental shelf waters up to 180 m (590 ft) in 

10 depth. They inhabit waters about 32 km (20 mi) offshore and inshore waters through freshwater 

11 creeks and rivers. Mangrove snappers use a wide variety of habitats, including mangrove, 

12 sandy grassbeds, and coral reefs. Mangrove snapper spawn pelagic eggs off shore near reefs 

13 from June to August. As larvae grow, they move inshore toward estuarine habitats, especially 

14 those with dense beds of Halodule and Syringodium sea grasses. As with adults, juveniles 

15 inhabit marine, estuarine, and riverine habitats. Juveniles and adults are most often found near 

16 mangroves, where they forage on small fish and crustaceans (Croker 1962; Patillo et al. 1997). 

17 Patillo et al. (1997) indicated that only adults and juvenile stages occur within Matagorda Bay 

18 and that even these stages are rare.

19 Red Drum. Red drum (Sciaenops ocellatus) occur throughout the Gulf of Mexico in shallow 

20 estuarine waters up to about 40 m (130 ft) off shore. They inhabit a variety of substrates, 

21 including seagrass, sand, mud, and oyster reefs, and can tolerate freshwater through high 

22 salinity waters. Red drum move to deep offshore waters in the fall where they spawn in inlet 

23 and bay mouths. Eggs hatch in the Gulf, and larvae make their way into estuaries where they 

24 remain until maturity. Larvae feed exclusively on mysids, amphipods, and shrimp. Juveniles 

25 most often inhabit shallow, protected waters with grassy or muddy bottoms and feed on crabs, 

26 shrimp, and small fish. As red drum grow, they shift more of their diet to crabs and eat less fish. 

27 Predators include many larger fish species, such as spot (Leiostomus xanthrus) and Atlantic 

28 croaker (Micropogon undulates), sharks, amberjacks (Seriola spp.), and other large piscivorous 

29 fish. Patillo et al. (1997) indicated that all life stages of red drum were common in Matagorda 

30 Bay.

31 Brown, White, and Pink Shrimp. Brown shrimp (Farfantepenaeus aztecus) inhabit rivers, 

32 estuaries, and offshore Gulf waters to depths of 100 m (330 ft). Adults spawn in spring and 

33 summer months in waters at least 18 m deep and of temperatures between 17 and 29 °C 

34 (63 to 84 °F). Eggs are demersal, and larvae are pelagic and feed on planktonic algae and 

35 zooplankton. On flood tides, larvae and juveniles move into estuaries with shallow waters and 

36 submerged aquatic vegetation. They are tolerant of a wide-range of salinities and have been 

37 recorded as occurring in waters from 0 to 70 ppt. Adults inhabit Gulf waters from mean low tide 

38 to the continental shelf in areas with silt, muddy sand, or sandy substrate.

39 White shrimp (Litopenaeus setiferus) inhabit shallower waters than brown shrimp—generally 

40 only out to a depth of 40 m (130 ft) but most often less than 27 m (89 ft). They spawn in waters 

41 of 9 to 34 m (30 to 110 ft) in spring, summer, and fall. On flood tides, larvae and juveniles move 

42 into estuaries with muddy or peat bottoms and significant amounts of detritus. Juvenile white 

43 shrimp are often more highly associated with marsh edges, and they feed on sand, detritus, 

44 organic matter, mollusk fragments, ostracods, copepods, and insect larvae. Similar to brown 

45 shrimp, white shrimp emigrate from rivers and estuaries to deeper Gulf waters as adults.

46 Pink shrimp (Farfantepenaeus duorarum) occupy deeper waters (up to 110 m (360 ft)) than 

47 either the brown or white shrimp. They spawn year-round at depths of 22 to 47 m (72 to 150 ft) 

48 and temperatures from 19.6 to 30.6 °C (67.3 to 87.1 °F). Post-larvae migrate to estuaries on 
Affected Environment 

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1 the flood tides at night in the spring and fall. They inhabit seagrass and mangrove habitats 

2 where they burrow into sand and shell mud substrate and return to the water column to feed at 

3 night. Juveniles eat a wide variety of organisms, including red and blue-green algae, diatoms, 

4 dinoflagellates, polychaetes, nematodes, shrimp, mysids, copepods, isopods, amphipods, 

5 mollusks, forams, and fish. Adults move from estuaries into Gulf waters with sand and shell 

6 substrate. They are most abundant in waters with depths of 9 to 48 m (30 to 160 ft).

7 Gulf Stone Crab. The Gulf stone crab (Menippe adina) occupies bottom habitats from less than 

8 1 m (3 ft) (shoreline) to depths of 61 m (200 ft). Adults seek out habitat in which they can 

9 burrow under the surface, including rock ledges, coral heads, seagrass patches, oyster bars, 

10 rock jetties, and artificial reefs. Adults feed mainly on oysters (Wilber 1989). Females maintain 

11 eggs on their abdomen until they hatch and become planktonic. As they metamorphose to 

12 larvae, they become epibenthic and settle to areas providing cover such as rubble and seagrass 

13 beds. Juveniles inhabit the bottom of the water column but do not burrow. Both adults and 

14 juveniles can tolerate salinities up to 33 ppt. Juveniles feed on small mollusks, worms, and 

15 crustaceans. Larvae require higher salinities of 30 to 35 ppt and warm water (greater than 

16 86 °F (30 °C)) for optimum growth and survival. All life stages of Gulf stone crab are considered 

17 common throughout the year in Matagorda Bay (Patillo et al. 1997).

18 EFH Species Identified During STP Aquatic Studies. This section briefly discusses EFH 

19 species in STP aquatic studies. Section 4.5 discusses these studies in detail. Of the nine 

20 species with designated EFH, two species (brown and white shrimp) have appeared in STP 

21 impingement or entrainment samples. ENSR (2008a) collected mangrove snapper via gill net, 

22 but this species has not appeared in impingement or entrainment samples. Additionally, 

23 ENSR (2008a) observed red drum, but ENSR did not collect this species in impingement and 

24 entrainment samples or with any of the sample gears.

25 McAden et al. (1984, 1985) conducted studies to estimate entrainment impacts by collecting 

26 surface plankton samples in front of the RMPF. McAden et al. (1984, 1985) also conducted 

27 impingement studies by washing all organisms off two intake screens and filtering them through 

28 a dip net. Section 4.5 discusses this study’s methods in more detail. McAden et al. undertook 

29 this study to confirm the accuracy of pre-operational entrainment and impingement loss 

30 predictions for 1975 through 1976. McAden (1984) collected the post-larval stage of brown and 

31 white shrimp sporadically in very low densities. Post-larval white and brown shrimp appeared in 

32 Colorado River plankton net, trawl, and seine samples sporadically and in very low densities 

33 (McAden et al. 1983). McAden et al. (1983, 1984) also collected white shrimp in plankton net 

34 samples in the siltation basin. White shrimp appeared in impingement samples in both 1983 

35 (16 individuals) and 1984 (4 individuals) in very low numbers (McAden et al. 1983, 1984). 

36 Brown shrimp did not appear in impingement samples in either year.

37 In 2007 and 2008, ENSR (2008a) conducted impingement and entrainment studies at the CWIS 

38 on the MCR from May 2007 through April 2008 as part of the STP, Units 3 and 4, COL 

39 application. Section 4.5 discusses this study’s methods. During the study, ENSR (2008a) 

40 collected two mangrove snappers via gill net in the MCR. In October 2007, mangrove snappers 

41 accounted for 2 percent of the fish in trawl samples. The species was not present, or accounted 

42 for less than 1 percent of trawl samples, for all other sample months. ENSR noted that several 

43 large schools of red drum were observed during the study, but none were collected in any of the 

44 sample gears during the study. Of the shrimp species, ENSR (2008a) collected white shrimp 

45 and brown shrimp in entrainment samples. These species made up 3 percent and less 

46 than 1 percent of total samples, respectively. ENSR did not collect any king mackerel, Spanish 

47 mackerel, pink shrimp, or Gulf stone crab in any of the study samples.
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1 2.2.8.7 Species Protected Under State of Texas Statutes

2 The Texas legislature authorized the TPWD to establish a list of State-endangered species 

3 in 1973, for animals, and in 1988, for plants. Title 5, Wildlife and Plant Conservation, 

4 Chapter 68, Endangered Species, of the State of Texas’s Statutes prohibits individuals from 

5 capturing, trapping, taking, or killing as well as possessing, selling, or distributing listed animal 

6 species. Chapter 88, Endangered Plants, prohibits individuals from collecting or selling listed 

7 plants obtained from public land without a TPWD-issued permit. Table 2–11 contains 

8 State-listed species that have the potential to occur on the STP site or along the transmission 

9 line corridors. Additionally, all Federally listed species that appear in Table 2–9 are 

10 State-protected as well.

11 Table 2–11. State-listed Species

Potential 

Occurrence(b)

Species Common Name State 

Status(a) Onsite Along Tline ROWs

Amphibians

Eurycea latitans Cascade Caverns salamander T x

Eurycea tridentifera comal blind salamander T x

Birds

Buteo albicaudatus white-tailed hawk T x x

Buteo albonotatus zone-tailed hawk T x

Egretta rufescens reddish egret T x x 

Falco peregrinus anatum American peregrin falcon T x x 

Falco peregrinus tundrius arctic peregrin falcon T x x 

Haliaeetus leucocephalus bald eagle T x x 

Mycteria americana wood stork T x x

Pelecanus occidentalis brown pelican E x x

Plegadis chihi white-faced ibis T x x

Sterna fuscata sooty tern T x x

Fish

Cycleptus elongatus blue sucker T x x

Satan eurystomus widemouth blindcat T x

Trogloglanis pattersoni toothless blindcat T x

Mollusks

Lampsilis bracteata Texas fatmucket T x

Quadrula aurea golden orb T x

Quadrula houstonensis smooth pimpleback T x x
Affected Environment 

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Potential 

Occurrence(b)

Species Common Name State 

Status(a) Onsite Along Tline ROWs

Quadrula petrina Texas pimpleback T x

Truncilla macrodon Texas fawnsfoot T x

Reptiles

Cemophora coccinea lineri Texas scarlet snake T x x

Crotalus horridus timber (canebrake) rattlesnake T x x

Drymarchon melanurus 

erebennus Texas indigo snake T x 

Gopherus berlandieri Texas tortoise T x x 

Liochlorophis vernalis smooth green snake T x 

Macrochelys temminckii alligator snapping turtle T x

Phrynosoma cornutum Texas horned lizard T x x

(a) E=endangered; T=threatened

(b) The STP site is located in Matagorda County. The transmission lines associated with the STP site traverse 

Matagorda County as well as Bexar, Brazoria, Colorado, DeWitt, Fayette, Gonzales, Guadalupe, Jackson, Lavaca, 

Wharton, and Wilson Counties.

Sources: NRC 2011b; STPNOC 2010b; TPWD 2011c, 2011f

1 2.2.9 Socioeconomics

2 This section describes current socioeconomic factors that have the potential to be directly or 

3 indirectly affected by changes in operations at STP, Units 1 and 2. STP, and the communities 

4 that support it, can be described as a dynamic socioeconomic system. The communities 

5 provide the people, goods, and services required to operate the nuclear power plant. Power 

6 plant operations, in turn, provide wages and benefits for people and dollar expenditures for 

7 goods and services. The measure of a communities’ ability to support STP, Units 1 and 2, 

8 operations depends on the ability of the community to respond to changing environmental, 

9 social, economic, and demographic conditions.

10 The socioeconomics region of influence (ROI) is defined by the area where STP, Units 1 and 2, 

11 employees and their families reside, spend their income, and use their benefits, thereby 

12 affecting the economic conditions of the region. The ROI consists of a two-county area 

13 (Brazoria and Matagorda Counties), where approximately 84 percent of STP employees reside.

14 STPNOC employs a permanent workforce of approximately 1,378 workers at STP, Units 1 

15 and 2, with approximately 84 percent living in Brazoria and Matagorda Counties (see

16 Table 2–12) (STPNOC 2010b). Of the remaining 16 percent of the workforce, most are divided 

17 among 18 counties across Texas and other states, with numbers ranging from 1 to 

18 62 employees per county. Given the residential locations of STP, Units 1 and 2, employees, the 

19 most significant impacts of plant operations are likely to occur in Brazoria and Matagorda 

20 Counties. The focus of the socioeconomic impact analysis in this SEIS is, therefore, on the 

21 impacts of continued STP, Units 1 and 2, operations on these two counties.
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1 Table 2–12. STP, Employee Residence by County

County # of Employees % of Total

Brazoria 298 22

Matagorda 851 62

Fort Bend 54 4

Wharton 62 4

Other 96 7

Other states 17 1

Total 1,378 100

Source: STPNOC 2010b 

2 Refueling outages at STP, Units 1 and 2, normally occur at 18-month intervals. During refueling 

3 outages, site employment increases by as many as 1,350 temporary workers for approximately 

4 1 to 2 months (STPNOC 2010b). Most of these workers are assumed to be located in the same 

5 geographic areas as STP, Units 1 and 2, employees. The following sections describe the 

6 housing, public services, offsite land use, visual aesthetics and noise, population demography, 

7 and the economy in the ROI surrounding STP, Units 1 and 2. 

8 2.2.9.1 Housing

9 Table 2–13 lists the total number of occupied and vacant housing units, vacancy rates, and 

10 median value in the two-county ROI. According to American Community Survey, there were 

11 approximately 138,000 housing units in the socioeconomic region, of which approximately 

12 117,000 were occupied. The median value of owner-occupied housing units in Brazoria and 

13 Matagorda Counties were $146,700 and $90,400 respectively. Brazoria County had a lower 

14 vacancy rate (12.6 percent) than Matagorda County, which had a 27.9 percent vacancy rate 

15 (USCB 2011).

16 Table 2–13. Housing in Brazoria and Matagorda Counties in 2010

Brazoria Matagorda ROI

Total units 118,813 18,827 137,640

Occupied housing units 103,828 13,568 117,396

Vacant units 14,985 5,259 20,244

Vacancy rate (%) 12.6 27.9 14.7

Median value ($)* 146,700 90,400 118,550

Key: * estimated

Source: USCB 2010

17 2.2.9.2 Public Services

18 Water Supply. Brazoria and Matagorda Counties are located in southeastern Texas. 

19 Information about municipal water suppliers in these counties, their permitted capacities or 

20 maximum design yields or both, reported annual peak usage, and population served are 

21 presented in Table 2–14. The Texas Water Development Board (TWDB) divided Texas into 
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1 16 water-planning regions (Region A through Region P). Brazoria County is located in 

2 Region H, while Matagorda County is located in Region K.

3 Brazoria County is 1 of 15 counties located in Region H, which includes the Houston 

4 metropolitan area. Over 20 percent of the State’s 2010 population resides in Region H. As 

5 seen in Table 2–14, the city of Pearland serves the largest population at 56,877 and has the 

6 highest average daily consumption (11.0 mgd), while the city of Clute serves the smallest at 

7 10,737 and has the lowest average daily consumption (0.361 mgd). Alvin serves 15 less people 

8 than Angleton but consumes slightly more water daily (EPA 2010).

9 Matagorda County is 1 of 14 counties located in Region K. Bay City, located approximately 

10 19.5 mi (31.4 km) north-northeast of STP, serves a population of 19,263 from a groundwater 

11 source with an average daily consumption of 2.41 mgd (EPA 2010).

12 STP withdraws potable water primarily from the deep-confined aquifer within the Beaumont 

13 Fountain. In 2009, STP withdrew 368,766,200 gal (1,395,931,917.5 liters) of water from five 

14 active onsite groundwater wells, of which 5 percent was used for sanitary and drinking 

15 purposes. STPNOC is permitted to withdraw an average of 2.7 mgd (STPNOC 2010b).

16 Table 2–14. Brazoria and Matagorda County City Public Water 

17 Supply Systems (in mgd)

Water Supplier

Primary Water 

Source

Average Daily

Demand (mgd)

System

Capacity (mgd)

Population

Served

Brazoria County

Alvin GW 2.18 8.74 19,152

Angleton SW 2.05 5.47 19,167

Clute SW 0.36 2.08 10,373

Freeport SW 1.40 0.00 (production vs. 

purchased) 12,708

Lake Jackson SW 3.10 6.69 25,890

Pearland SW 11.00 15,26 56,877

Matagorda County

Bay City GW 2.41 8.86 19,263

Surface Water = SW, Groundwater = GW

Source: EPA 2010

18 Education. Brazoria County has eight school districts consisting of 4 pre-kindergarten, 

19 43 elementary, 23 middle/junior high/intermediate, 15 high schools, 10 alternative, 1 charter, 

20 and 1 grade 9 school. During the 2009 to 2010 school year, enrollment was 60,251 

21 (NCES 2011).

22 Matagorda County has five districts consisting of 8 pre-kindergarten, 8 elementary, 

23 4 middle/junior high/intermediate, 4 high schools, and 1 alternative school. During the 2009 to 

24 2010 school year, enrollment was 7,185 (NCES 2011).

25 Transportation. STP is located in an area severed by U.S. highways, FMs, and county roads. 

26 Within 50 miles of STP, there are no interstate highways; however, there are two U.S. highways 

27 (U.S. 59 and U.S. 87). U.S. 59 runs northeast to southwest connecting Fort Bend, Wharton, 
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1 Jackson, and Victoria Counties. U.S. 87 runs northwest to southeast connecting Victoria and 

2 Calhoun County.

3 STP can be accessed by FM 521, which runs east and west. FM 521 is accessible by several 

4 FM and State highways, which would be most commonly commuted by STP workers. Workers 

5 traveling from the east side of Matagorda County and all of Brazoria County would likely take 

6 TX-60 south and exit at FM 521. Workers commuting from the north would likely travel on 

7 TX-35 west, exiting on to FM 1468 south or FM 1095 south. Workers arriving from the west are 

8 likely to travel on TX-35 east, exiting onto FM 521 east. 

9 Table 2–15 lists commuting routes to STP and average annual daily traffic (AADT) volume 

10 values. The AADT values represent traffic volumes for a 24-hour period factored by both day of 

11 week and month of year.

12 Table 2–15. Major Commuting Routes in the Vicinity of STP, 2010 AADT

Roadway & Location AADT (a)

TX-60 South from Bay City to FM 521 West 2,400–3,000

FM 2078 West to FM 2668 South 310

FM 2668 South from Bay City to FM 521 West 1,050–2,200

FM 1468 South from TX-35 to FM 521 East 700–940

FM 1095 South from TX-35 to FM 521 East 390–630

FM 2853 South to FM 521 East 510–580

FM 521 West from TX-60 1,600–2,500

FM 521 East from FM 1095 1,150

(a) All AADTs represent traffic volume during the average 24-hour day during 2010.

Key: FM = Farm-to-Market; TX = Texas 

Source: TXDOT 2011

13 2.2.9.3 Offsite Land Use

14 Offsite land use conditions in Brazoria and Matagorda Counties are described in this section. 

15 Approximately 84 percent of the STP permanent workforce lives in these two counties. Within 

16 the region of STP, approximately 61 percent of the land is agricultural, 18 percent forest, 

17 10 percent rangeland, 5 percent wetland, 2.5 percent urban or developed land, 2 percent

18 freshwater bodies, and less than 1 percent barren land (STPNOC 2010d).

Brazoria County occupies approximately 1,350 mi2 (3,496 km2 19 ) (USCB 2010). Agricultural land 

20 is principally used as pasture (52.8 percent) and cropland (35.2 percent). Livestock (mostly 

21 cattle and calves) comprise 45 percent of the total market value of agricultural products 

22 (livestock and crop product) sold in the county while crop sales comprise the remaining 

23 55 percent (mostly grains, dry beans and peas, nursery, and floriculture). The number of farms 

24 in Brazoria increased about 5 percent from 2002 to 2007. Farmland acreage in the county 

25 decreased 14 percent during the same period, and the average size of a farm decreased 

26 18 percent to 205 ac (82 ha) (NASS 2009).

Matagorda County occupies approximately 1,100 mi2 (2,849 km2 27 ) (USCB 2010). Agricultural 

28 land is principally used as pasture (51.08 percent) and cropland (40.63 percent). Crop sales 

29 (mostly nursery, greenhouse, floriculture, and sod) comprise 57 percent of the market value of 
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1 agricultural products sold from Matagorda County. Livestock sales (agricultural products of 

2 mostly cattle and calves) comprise the remaining 43 percent. The number of farms in 

3 Matagorda County decreased from 2002 to 2007 by 9 percent. The number of farmland acres 

4 decreased by 7 percent; however, the average size of farms increased by 2 percent from 625 ac 

5 to 640 ac (NASS 2009).

6 Even though population growth is projected to continue, there is ample urban and rural land to 

7 accommodate the anticipated growth over the next 20 years. However, agriculture will continue 

8 to be the major land use outside urban areas.

9 2.2.9.4 Visual Aesthetics and Noise

10 The STP site boundary encloses approximately 

11 12,220 ac, with site buildings, operations area, 

12 support facilities, and transmission ROWs

13 occupying approximately 65 ac. Approximately 

14 7,046 ac are occupied by other STP features, the 

15 ECP, and the MCR (STPNOC 2010b).

16 The site includes approximately 1,700 ac of 

17 undeveloped natural lowland habitat, with characteristics of the Texas Coastal Plain Province, 

18 and the land surrounding the site is used for ranchland and farmland (STPNOC 2010b). STP is 

19 situated on low elevation, generally less than 60 feet MSL, with open prairie habitat interspersed 

20 with creek and river drainages flowing toward the Gulf coasts marshes. Trees are rare but can 

21 be found along streams and in oak groves (STPNOC 2010d). Given the flat nature of the land, 

22 the STP reactors are a prominent feature of the area, and the MCR is visible from the southeast 

23 along the Colorado River as well as other points around the site.

24 Noise from nuclear plant operations can be detected off site. Sources of noise at STP include 

25 the turbines and large pump motors. Given the industrial nature of the station, noise emissions 

26 from the station are generally nothing more than an intermittent minor nuisance. However, 

27 noise levels may sometimes exceed the 55 dBA level that EPA uses as a threshold level to 

28 protect against excess noise during outdoor activities (EPA 1974). However, according to EPA, 

29 this threshold does “not constitute a standard, specification, or regulation,” but it was intended to 

30 provide a basis for State and local governments establishing noise standards. 

31 2.2.9.5 Demography

32 According to 2000 Census information, an estimated 35,291 people lived within 20 mi (32 km) of 

33 STP, which equates to a population density of 36 persons per square mile (STPNOC 2010b). 

34 This translates to a Category 1, “most sparse,” population density using the GEIS measure of 

35 sparseness (i.e., less than 40 persons per square mile and no community with 25,000 or more 

36 people within 20 mi). Based on the GEIS proximity matrix, the STP proximity population density 

37 is classified as Category 2 (no city with 100,000 or more people and less than 50 persons per 

38 square mile within 50 mi). Therefore, with STP regional population classifications of sparseness 

39 Category 1 and proximity Category 2, STP lies in a low-population area.

40 Table 2–16 shows population projections and growth rates from 1970 to 2050 in Brazoria and 

41 Matagorda Counties in Texas. The growth rate in Brazoria County showed an increase in 

42 population of nearly 30 percent between 2000 and 2010. Conversely, Matagorda County 

43 showed a 3.3 percent decrease in population between 2000 and 2010. Both county populations 

44 are projected to increase each decade through 2050. 

The EPA generally uses 55 decibels (dBA) as the 

noise threshold level to protect against excess 

noise during outdoor activities. However, 

according to EPA, this threshold does “not 

constitute a standard, specification, or regulation,” 

but it was intended to provide a basis for State 

and local governments establishing noise 

standards.
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1 Table 2–16. Population and Percent Growth in Brazoria and Matagorda Counties 

2 from 1970 to 2010 and Projected for 2020 to 2050

Year Brazoria % Change Matagorda % Change

1970 108,312 N/A 27,913 N/A

1980 169,587 56.6 37,828 35.5

1990 191,707 13.0 36,928 -2.4

2000 241,767 26.1 37,957 2.8

2010 313,166 29.5 36,702 -3.3

2020 349,474 11.6 40,789 11.1

2030 397,663 13.8 42,559 4.3

2040 445,852 12.1 44,330 4.2

2050 494,041 10.8 46,101 4.0

Source: USCB (2011) provided the population data for 1970 through 2010. The data forecast for 2020 through 2050

was calculated. 

3 Demographic Profile. The 2010 demographic profiles of the two-county ROI population are

4 presented in Table 2–17. In 2010, minorities (race and ethnicity combined) comprised 

5 47.4 percent of the total two-county population. The minority population is largely Hispanic or 

6 Latino (28.8 percent) with the next largest minority population being Black or African American 

7 (11.7 percent).

8 Table 2–17. Demographic Profile of the Population in the 

9 STP Two-County Socioeconomic ROI in 2010

Brazoria Matagorda ROI

Total population 313,166 36,702 349,868

Race (not Hispanic or Latino)—% of total population

White 53.2 47.4 52.6

Black or African American 11.8 11.1 11.7

American Indian & Alaska Native 0.3 0.3 0.3

Asian 5.4 1.9 5.1

Native Hawaiian & Other Pacific Islander 0.0 0.0 0.0

Some other race 0.2 0.1 0.1

Two or more races 1.4 0.9 1.4

Ethnicity

Hispanic or Latino 86,646 14,047 100,717

% of total population 27.7 38.3 28.8
Affected Environment 

2-64

Brazoria Matagorda ROI

Total minority 146,492 19,302 165,794

% minority 46.8 52.6 47.4

Source: USCB 2010

1 Transient Population. Within 50 mi (80 km) of STP, colleges and recreational opportunities 

2 attract daily and seasonal visitors who create demand for temporary housing and services. In 

3 2010, there were approximately 11,118 students attending colleges and universities within 50 mi 

4 (80 km) of STP (IES 2010).

5 In 2000, 1.7 percent of all housing units were considered temporary housing for seasonal, 

6 recreational, or occasional use in Brazoria County. By comparison, seasonal housing 

7 accounted for 12.9 percent of total housing units in Matagorda County (USCB 2010). Calhoun 

8 and Jackson Counties have the highest percent of temporary housing for seasonal, recreational, 

9 or occasional use, at 17.1 and 18.5 percent, respectively (USCB 2010). Table 2–18 provides 

10 information on seasonal housing for the nine counties located all or partly within 50 mi of STP.

11 Table 2–18. Seasonal Housing in Counties Located within 50 mi of STP

County (a) Housing Units

Vacant Housing Units: For Seasonal, 

Recreational, or Occasional Use % 

Texas

Brazoria 90,628 1,496 1.7

Calhoun 10,238 1,757 17.1

Colorado 9,431 634 6.7

Fort Bend 115,991 5,076 4.4

Jackson 6,545 1,209 18.5

Lavaca 9,657 377 3.9

Matagorda 18,611 2,407 12.9

Victoria 32,945 261 0.8

Wharton 16,606 291 1.8

Total 310,652 13,508 7.5

(a) Counties within 50 mi (80 km) of STP with at least one block group located within the 50-mi (80 km) radius 

Source: USCB 2010

12 Migrant Farm Workers. Migrant farm workers are individuals whose employment requires travel 

13 to harvest agricultural crops. These workers may or may not have a permanent residence. 

14 Some migrant workers follow the harvesting of crops, particularly fruit, throughout rural areas of 

15 the U.S. Others may be permanent residents near the STP site who travel from farm to farm 

16 harvesting crops.

17 Migrant workers may be members of minority or low-income populations. Because they travel 

18 and can spend a significant amount of time in an area without being actual residents, migrant 

19 workers may be unavailable for counting by census takers. If uncounted, these workers would 

20 be “underrepresented” in USCB minority and low-income population counts.
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1 Information on migrant farm and temporary labor was collected in the 2007 Census of 

2 Agriculture. Table 2–19 provides information on migrant farm workers and temporary farm labor 

3 (less than 150 days) within 50 mi of the STP. According to the 2007 Census of Agriculture, 

4 approximately 6,513 farm workers were hired to work for less than 150 days and were 

5 employed on 2,233 farms within 50 mi of the STP. The county with the largest number of 

6 temporary farm workers (1,176) on 396 farms was Wharton County, Texas (NASS 2011).

7 In the 2002 Census of Agriculture, farm operators were asked for the first time whether or not 

8 they hired any migrant workers, defined as a farm worker whose employment required travel 

9 that prevented the migrant worker from returning to his or her permanent place of residence the 

10 same day. In the 50-mi radius of STP, 185 farms reported hiring migrant workers in the 2007 

11 Census of Agriculture. Lavaca and Wharton Counties reported the most farms (35 and 31, 

12 respectively) with hired migrant workers, followed by Brazoria and Fort Bend County, with 

13 28 and 25 farms, respectively (NASS 2011).

14 According to the 2007 Census of Agriculture estimates, 1,001 temporary farm workers (those 

15 working fewer than 150 days per year) were employed on 414 farms in Brazoria County, and 

16 754 temporary farm workers were employed on 247 farms in Matagorda County, respectively 

17 (NASS 2011).

18 Table 2–19. Migrant Farm Workers and Temporary Farm Labor in Counties 

19 Located within 50 mi of STP

County (a)

Number of Farms 

with Hired Farm 

Labor (b)

Number of Farms 

Hiring Workers for 

Less Than 150 Days (b)

Number of Farm 

Workers Working for 

Less Than 150 days (b)

Number of Farms 

Reporting 

Migrant Farm 

Labor (b)

Texas

Brazoria 414 332 1,001 28

Calhoun 66 54 143 4 

Colorado 372 319 853 23

Fort Bend 299 230 621 25

Jackson 200 164 408 12

Lavaca 475 410 925 35

Matagorda 247 208 754 16

Victoria 252 216 632 11

Wharton 396 300 1,176 31

Total 2,721 2,233 6,513 185

(a) Counties within 50 mi of STP with at least one block group located within the 50-mi radius

(b) Table 7. Hired Farm Labor—Workers and Payroll: 2007 Census of Agriculture

Source: NASS 2009

20 2.2.9.6 Economy

21 Employment and Income. Between 2000 and 2010, the civilian labor force in Brazoria County 

22 increased 34.5 percent from 112,798 to 151,791. Matagorda County also increased during that 
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1 time, 5.6 percent from 16,434 to 17,365 (USCB 2010). Major industries in Matagorda County 

2 are presented in Table 2–20. 

3 According to 2008 through 2010 American Community Survey 3-Year Estimates, educational, 

4 health, and social services industry employs the most workers in the socioeconomic ROI 

5 (22.5 percent) followed by wholesale trade (16.7 percent). A list of employment by industry in 

6 the ROI is presented in Table 2–21. 

7 Table 2–20. Major Industries in Matagorda County

Company Name Type of Business

STPNOC Electricity generation

Lyondell Basell High density polyethylene resins

Valerus Compressors Compressor fabrication

McAda Drilling Fluids Oilfield support

OXEA Corporation Chemical products

Celanese Chemical products

Henderson Fabrication Steel fabrication

Source: Matagorda County EDC 2007

8 Table 2–21. Major Industries in ROI

Industry Brazoria Matagorda Total %

Total employed civilian workers 142,741 15,080 157,821

Agriculture, forestry, fishing & hunting, & mining 3,677 1,560 5,237 3.3

Construction 14,889 1,274 16,163 10.2

Manufacturing 17,962 1,422 19,384 12.3

Wholesale trade 4,638 310 26,299 16.7

Retail trade 13,694 2,273 15,967 10.1

Transportation, warehousing, & utilities 7,362 1,643 9,005 3.8

Information 2,382 219 2,601 1.6

Finance, insurance, real estate, rental, & leasing 7,061 458 7,519 4.8

Professional, scientific, management, 

administrative, & waste management services 15,182 812 15,994 10.1

Educational, health, & social services 32,613 2,887 35,500 22.5

Arts, entertainment, recreation, 

accommodation, & food services 9,196 960 10,156 6.4

Other services (except public administration) 7,758 802 8,560 5.4

Public administration 6,057 460 6,517 4.1

Source: USCB 2010 
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1 Estimated income information for the STP ROI is presented in Table 2–22. According to the 

2 USCB, people living in Brazoria County had a higher median household and per capita income 

3 than the State average, while Matagorda had a lower median household and per capita income 

4 (UCSB 2010). An estimated 10.6 and 19.2 percent of the population in Brazoria and Matagorda 

5 Counties were living below the official poverty level, respectively. The State of Texas as a 

6 whole had a higher percentage of persons living below the poverty level (17 percent) than 

7 Brazoria County, but lower than Matagorda County. The percentage of families living below the 

8 poverty level in Brazoria County (8.2 percent) was lower than the State of Texas average 

9 (13.2 percent), but Matagorda County (17.4 percent) was higher than the State average 

10 (UCSB 2010).

11 Table 2–22. Estimated Income Information for STP ROI

Brazoria Matagorda Texas

Median household income (dollars) (a) 66,221 41,586 49,585

Per capita income (dollars) (a) 27,381 23,138 24,671

Individuals living below the poverty level (percent) 10.6 19.2 17

Families living below the poverty level (percent) 8.2 17.4 13.2

(a) In 2008 inflation-adjusted dollars

Source: USCB 2011

12 Unemployment. According to the USCB’s 2006 through 2008 American Community Survey 

13 3-Year Estimates, the unemployment rates in Brazoria and Matagorda Counties were 4.0 and 

14 8.1 percent, respectively, in comparison to the unemployment rate of 4.8 percent for the State of 

15 Texas (USCB 2010).

16 Taxes. All privately owned property in Texas is subject to taxation by the county and school 

17 district in which it is located, unless specifically exempted by the Texas Constitution. Most 

18 private property owners in Texas also pay property taxes to local jurisdictions like cities and 

19 special districts within whose boundaries they reside. As such, property tax revenues are the 

20 major tax revenue source for counties and cities and the sole source of tax revenue for school 

21 districts. Exemptions from these standard practices are governed by the State, while county 

22 appraisal districts determine the value of properties with local jurisdictions setting the tax rates. 

23 After assessment, private property owners then make a consolidated payment to the County 

24 Tax Assessor, who retains the county’s portion and distributes the special district funds to the 

25 special districts, as appropriate (STPNOC 2010b).

26 STPNOC, owner of STP, Units 1 and 2, pays the majority of property taxes to the following 

27 taxing jurisdictions: Matagorda County, Matagorda County Hospital District, Navigation 

28 District #1, Drainage District #3, Palacios Seawall District, and the Coastal Plains Groundwater 

29 District (STPNOC 2010b). Table 2–23 presents each district’s total property tax levies, STP 

30 payments, and the proportion of the total constituted by STP. STP payments represent a major 

31 portion of property tax revenues for each of the districts, ranging from 22 percent to 75 percent

32 in the various districts from 2004 to 2008. From 2003 to 2007, in Matagorda County specifically 

33 (excluding special districts within the county), STP property tax payments to Matagorda County 

34 alone have represented approximately one-third of the county’s total revenues (total revenues 

35 include property tax payments and other sources). In 2001, STPNOC negotiated an agreement 

36 with Matagorda County (to begin in 2002) to remit a county service fee in lieu of property taxes 

37 to the county, with a revenue cap of $6.1 million. STPNOC has a similar agreement with the 
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1 local hospital district, capped at $2.6 million, to compensate the hospital for its extensive 

2 support of STPNOC’s emergency response requirements (STPNOC 2010b).

3 Table 2–23. Comparison of STP Owner Payments with Taxing District Property Tax

Year(a) Taxing District Property Tax Levy($) (b)

Total STP

Payments($) (c)

% of Property Tax 

Levy

2003 Matagorda County (d) 8,214,934 6,100,000 74.3

Matagorda County 

Hospital(d) 4,126,692 2,461,132 59.6

Navigation District #1 459,261 360,394 78.5

Drainage District #3 288,179 249,859 86.7

Palacios Seawall 499,121 411,000 82.3

Coastal Plains 

Groundwater 137,930 45,264 32.8

Total 13,726,117 9,627,649 70.1

2004 Matagorda County(d) 8,122,946 6,100,000 75.1

Matagorda County 

Hospital(d) 5,254,940 2,526,807 48.1

Navigation District #1 413,867 360,410 87.1

Drainage District #3 287,909 249,869 86.8

Palacios Seawall 433,674 411,018 94.8

Coastal Plains 

Groundwater 136,040 45,266 33.3

Total 14,649,376 9,693,370 66.2

2005 Matagorda County(d) 8,191,213 6,100,000 74.5

Matagorda County 

Hospital(d) 5,613,566 2,343,558 41.7

Navigation District #1 370,191 251,822 68.0

Drainage District #3 254,311 203,684 80.1

Palacios Seawall 329,155 223,926 68.0

Coastal Plains 

Groundwater 141,239 31,628 22.4

Total 14,899,675 9,154,618 61.4

2006 Matagorda County(d) 9,038,864 6,100,000 67.5

Matagorda County 

Hospital(d) 5,753,331 2,567,253 44.6

Navigation District #1 486,645 342,148 70.3
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Year(a) Taxing District Property Tax Levy($) (b)

Total STP

Payments($) (c)

% of Property Tax 

Levy

Drainage District #3 242,142 200,299 82.7

Palacios Seawall 327,813 230,162 70.2

Coastal Plains 

Groundwater 153,850 39,422 25.6

Total 16,002,645 9,479,284 59.2

2007 Matagorda County(d) 9,785,561 6,100,000 62.3

Matagorda County 

Hospital(d) 6,236,490 2,600,000 41.7

Navigation District #1 519,472 377,347 72.6

Drainage District #3 229,254 190,125 82.9

Palacios Seawall 276,122 200,131 72.5

Coastal Plains 

Groundwater 166,556 45,019 27.0

Total 17,213,455 9,512,622 55.3

2008 Matagorda County(d) 10,968,961 6,100,000 55.6

Matagorda County 

Hospital(d) 7,035,468 2,600,000 37.0

Navigation District #1 547,517 405,019 74.0

Drainage District #3 246,398 202,883 82.3

Palacios Seawall 276,565 203,844 73.7

Coastal Plains 

Groundwater 187,828 48,454 25.8

Total 19,262,737 9,560,200 49.6

6-Year Total 95,754,005 57,027,743 59.6

(a) Year levy and rate are for the following budget year. STP, Units 1 and 2, owners pay the standard millage rate for 

the special districts.

(b) Total levies for 2003–2007 are from the Texas Comptroller of Public Accounts, Annual Property Tax Reports for 

Tax Years 2003, 2004, 2005, and 2006, as well as 2007 Property Tax Rates and Taxes. Total levies for 2008 are 

from the Matagorda County Tax Office.

(c) For 2003–2006, tax payments are based on estimates from the Matagorda County Tax Office. For 2007 and 

2008, estimated payments are based on actual NRG property tax statements.

(d) Payments to Matagorda County and the Matagorda County Hospital District are based on an agreement between 

those entities and STPNOC, which sets a fixed amount to be paid each year.

Note: Totals may not add due to rounding.

Source: STPNOC 2010b 

1 In addition to tax payments to the districts discussed above, STP pays taxes to other districts 

2 within Matagorda County for undeveloped portions of the STP plant site that lie within other 
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1 taxing districts and for other STP-related property within the county. The receiving districts are

2 the Port of Bay City Conservation and Reclamation District, Drainage Districts 1 and 2, and the 

3 City of Bay City. Per State of Texas tax law, STP also pays taxes to three of the five 

4 independent school districts (ISDs) in Matagorda County—Matagorda, Bay City, and Tidehaven. 

5 Table 2–24 shows these payments. These payments represent a small proportion of those 

6 districts’ total levies in comparison to the percentages of the main district payments shown 

7 above.

8 Table 2–24. STP, Units 1 and 2, Owner Payments to Other Taxing Districts in Matagorda

2007 2008

Special District (a)

STP Owner 

Payments ($)

District’s Est. 

Total Levy, 

2007 ($)

STP as 

% of 

Total

STP Owner 

Payments

($)

District’s 

Est. Total 

Levy, 2008

($)

STP as 

% of 

Total

Port of Bay City 3,097 723,680 0.43 5,080 388,907 0.61

Conservation & 

Reclamation District 468 112,458 0.42 774 130,055 0.60

Matagorda ISD 74,943 2,525,549 2.97 75,038 2,677,920 2.80

Drainage District #1 6,419 1,607,005 0.40 6,179 1,681,062 0.37

Drainage District #2 2,000 342,514 0.58 6,278 419,134 1.50

Bay City ISD 0 12,840,989 - 1,942 14,265,846 0.01

Tidehaven ISD 22,837 5,029,792 0.45 79,465 6,541,043 1.21

City of Bay City 0 2,746,295 - 747 3,050,691 0.02

Total 111,771 25,925,282 0.43 175,502 29,599,657 0.59

(a) “Other” = Taxing districts (Special District) other than Matagorda County; Matagorda County Hospital; Navigation 

District #1; Palacios Seawall District; Coastal Plains Groundwater District; and Drainage District #3.

Source: STPNOC 2010b 

9 STP is located in the Electric Reliability Council of Texas region, a deregulated area that is not 

10 set to change in the foreseeable future. As such, STPNOC’s future taxation will continue to be 

11 based on the market value of the site and agreements with the county regarding service fees in 

12 lieu of property taxes (STPNOC 2010b).

13 2.2.10 Historic and Archaeological Resources

14 In accordance with 36 CFR 800.8(c), the NRC has elected to use the National Environmental 

15 Policy Act of 1969, as amended (NEPA), process to comply with the obligations under 

16 Section 106 of the National Historic Preservation Act (NHPA). In addition, NUREG-1555 

17 (NRC 2000) provides guidance to staff on how to conduct historic and cultural resource analysis 

18 in its environmental reviews.

19 In the context of NHPA, the NRC has determined that the area of potential effect (APE) for a 

20 license renewal action is the area at the power plant site and its immediate environment that 

21 may be affected by post–license renewal and land-disturbing activities associated with the 

22 proposed action (NRC 2011e). The APE may extend beyond the immediate environs in 

23 instances where post–license renewal and land-disturbing activities or refurbishment activities 
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1 specifically related to license renewal may potentially have an effect on historic properties 

2 (NRC 2011e).

3 Cultural Background. Substantial archaeological records indicate that there was prehistoric 

4 occupation of the STP area. During the Paleoindian era (pre-7800 B.C.), the earliest inhabitants 

5 of Texas were the Clovis and Folsom peoples, which are typically associated with the hunting of 

6 the extinct mammoth and bison, respectively. The Early Archaic era (7800 B.C. to 6000 B.C.) 

7 represents a time when inhabitants became more settled, and numerous distinctive triangular 

8 points and barbed specimens are noted from this era. The Middle Archaic period (6000 B.C. 

9 to 2500 B.C.) reflects a diversity of stone tools and shell middens, while the Late Archaic era 

10 (2500 B.C. to 700 B.C.) is marked by distinctive projectile points and stone tools. The 

11 Late Prehistoric era (700B.C. to 1500 A.D.) is noted for the introduction of the bow and arrow 

12 and pottery (NRC 2011b).

13 Hundreds of tribes inhabited Texas, and historians have a difficult time tracing their origin 

14 because there are few written records from this period (University of Texas at Austin 2011). 

15 The historic period can be traced to the 1500s, when the Spanish and French explored the 

16 Texas Coast. With the arrival of the Europeans, there were many changes for the native 

17 peoples. Diseases destroyed many populations, and several tribes fled to and from the area 

18 that makes up the State of Texas today. Matagorda County was created in 1837, soon after 

19 Texas gained its independence from Mexico (NRC 2011b). Today, there are three indigenous 

20 groups living within the Texas boarders that are listed among the Nation’s many Federally 

21 recognized tribes—the Alabama–Coushatta Tribe in East Texas; the Ysleta del Sur Pueblo, or 

22 Tigua, in far West Texas; and the Kickapoo Traditional Tribe in southwest Texas along the 

23 Texas–Mexico border (THC 2011). Other recognized tribes maintain ties to their ancestors’ 

24 homelands in the State of Texas and monitor sites throughout the State that are important to 

25 their tribe and their history (THC 2011). Further cultural background is documented in the NRC 

26 EIS (2011b) for the review of the STP, Units 3 and 4, combined license application. 

27 Historic and Archaeological Resources at the STP Site. This section discusses the known 

28 historic and archaeological resources at the STP site and in the surrounding area. The 

29 following information was used to identify the historic and archaeological resources at the STP 

30 site:

31 • original construction FES (NRC 1975); 

32 • original ER (HL&P 1975), which included the Texas Archaeological Survey 

33 Report (Hall and Ford 1973); 

34 • original operation EIS (NRC 1986); 

35 • STP, Units 3 and 4, ER, Revision 4 (STPNOC 2010d); 

36 • STP, applicant’s ER, operating license renewal stage, STP, Units 1 and 2 

37 (STPNOC 2010b); 

38 • EIS for COLs for STP, Units 3 and 4 (NRC 2011b); 

39 • audit report regarding STP LRA—cultural resources (NRC 2011g); 

40 • STP, RAI responses (STPNOC 2011g); 

41 • consultation with THC (Texas Historical Commission); and 

42 • consultation with tribes.
Affected Environment 

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1 In the early 1970s, the Texas Archaeological Survey conducted cultural resources investigations 

2 of the STP site and surrounding area. The investigations included a literature review, a 

3 pedestrian survey, and limited subsurface testing (NRC 2011b; STPNOC 2010b, 2010d). The 

4 construction of STP, Units 1 and 2, was completed in the 1980s, and much of the site had been 

5 heavily disturbed by construction activities and the creation of the reservoir.

6 STP identified three cultural resource sites within 10 mi of the STP site. Cultural resources 

7 site 41MG48 is approximately 5 mi from the northeast boundary of the STP site and is 

8 described as a late 19th century artifact scatter associated with homesteading Artifacts 

9 consisted of ceramic, glass, and metal with manufacturing dates between 1890 and 1910. STP 

10 reported that a homestead was established in the 1890s and dissolved in 1946. Cultural 

11 resource investigations concluded that the site was not significant and that no further work on 

12 the site was needed.

13 The closest recorded site is 41MG49, and it is approximately 4 mi from the northeastern 

14 boundary of the STP site. Site 41MG49 was originally reported in the license renewal ER as 

15 having no site form record (STPNOC 2010b). In July 2011, STP revisited the information and 

16 discovered the missing site form record for site 41MG49 that described it as a shell midden with 

17 no associated artifacts(STPNOC 2011g). Cultural resource investigations concluded that the 

18 site was significant and should be studied further if the site were to be affected.

19 Site 41MG112 is approximately 5 mi from the northeastern boundary of the STP site and is 

20 described as a dismantled historic farmstead dating to the mid-20th century. Cultural resource 

21 investigations concluded that the site was not significant and that no further work on the site 

22 was needed (STPNOC 2011g). These three sites (41MG48, 41MG49, and 41MG112) are 

23 located outside of the. There are no recorded historic or archaeological resources on the STP 

24 site.

25 STP identified a potential historic gravesite in its ER (STPNOC 2010b) located on the southeast 

26 corner of the STP site. The NRC staff reviewed information during the environmental audit for 

27 cultural resources at the STP site and discussed the status and protection of the historic 

28 gravesite with STP environmental staff (NRC 2011g). STP staff had interviewed descendants of 

29 the former property owner and confirmed the presence of a historic grave from the late 1800s; 

30 however, this gravesite is not recorded and little is known about it (STPNOC 2011g). 

2.3

32 The NRC reviewed the possibility that activities of other Federal agencies might impact the 

33 renewal of the operating license for STP. There are no Federal projects that would make it 

34 necessary for another Federal agency to become a cooperating agency in the preparation of 

35 this draft Supplemental EIS. There are no known American Indian lands within 50 mi of STP. 

36 Federally owned facilities within 50 mi of STP include (NRC 2011b): 

31 Related Federal and State Activities

37 • Big Boggy—administered by the FWS—is a 5,000-ac national wildlife refuge 

38 that borders Matagorda Bay and is approximately 9 mi southeast of the STP 

39 site. 

40 • San Bernard—administered by the FWS—is a 45,311-ac national wildlife 

41 refuge that contains coastal prairies and salt marshes in southern Matagorda 

42 and Brazoria Counties. 

43 The NRC is required under Section 102(2)(C) of NEPA to consult with and obtain the comments 

44 from any Federal agency that has jurisdiction by law or special expertise with respect to any 

45 environmental impact involved in the subject matter of the EIS. For example, during the course 
Affected Environment

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1 of preparing this DSEIS, the NRC consulted with the FWS and the NMFS. A complete list of 

2 key consultation correspondences is listed in Appendix D.

3 Regarding Coastal Zone Management Act (CZMA) compliance status, pursuant to 

4 Section 506.11(13) of Texas Administrative Code, STP license renewal falls within the definition 

5 of Federal agency action: 

6 A federal license or permit that a federal agency may issue that represents the 

7 proposed federal authorization, approval, or certification needed by the applicant 

8 to begin an activity. An action to renew, amend, or modify an existing license or 

9 permit shall not be considered an action subject to the CMP [Coastal 

10 Management Program] if the action only extends the time period of the existing 

11 authorization without authorizing new or additional work or activities, would not 

12 increase pollutant loads to coastal waters or result in relocation of a wastewater 

13 outfall to a critical area, or is not otherwise directly relevant to the policies in 

14 §501.14 of this title (relating to Policies for Specific Activities and Coastal Natural 

15 Resource Areas).

16 In addition, in a letter dated January 29, 2010, the Coastal Coordination Council that 

17 administers the CZMA compliance in Texas explained: 

18 The project [STP] was undertaken before Texas had a federally approved [CMP]

19 and based on information provided in the [STPNOC’s] letter dated

20 December 2, 2009, it has been determined that there are no significant 

21 unresolved consistency issues. Therefore, pursuant to Section 506.11(13), this 

22 project is consistent with the CMP goals and policies.

23 Hence, for license renewal purpose, STPNOC has obtained and maintained a consistency 

24 certification in accordance with the CZMA.

2.4

26 10 CFR Part 20. Code of Federal Regulations, Title 10, Energy, Part 20, “Standards for 

27 protection against radiation.”

25 References 

28 10 CFR Part 50. Code of Federal Regulations, Title 10, Energy, Part 50, “Domestic licensing of 

29 production and utilization facilities.”

30 10 CFR Part 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental 

31 protection regulations for domestic licensing and related regulatory functions.”

32 10 CFR Part 54. Code of Federal Regulations, Title 10, Energy, Part 54, “Requirements for 

33 renewal of operating licenses for nuclear power plants.”

34 10 CFR Part 61. Code of Federal Regulations, Title 10, Energy, Part 61, “Licensing 

35 requirements for land disposal of radioactive waste.”

36 10 CFR Part 71. Code of Federal Regulations, Title 10, Energy, Part 71, “Packaging and 

37 transportation of radioactive material.”

38 30 TAC 1-307. Texas Administrative Code, Title 30, Environmental Quality, Part 1, “Texas 

39 Commission on Environmental Quality,” Chapter 307, “Texas Surface Water Quality Standards.” 

40 31 TAC 10-356. Texas Administrative Code, Title 31, Natural Resources and Conservation, 

41 Part 10, “Texas Water Development Board,” Chapter 356, “Groundwater Management.” 

42 36 CFR Part 800. Code of Federal Regulations. Title 36, Parks, Forests, and Public Property, 

43 Part 800, “Protection of historic properties.” 
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29 for License Renewal of Nuclear Plants. Washington, DC: NRC. NUREG-1437. May 1996. 

30 ADAMS Nos. ML040690705 and ML040690738.

31 [NRC] U.S. Nuclear Regulatory Commission. 1999. Section 6.3—Transportation, Table 9.1, 

32 Summary of findings on NEPA issues for license renewal of nuclear power plants. In: Generic 

33 Environmental Impact Statement for License Renewal of Nuclear Plants. Washington, DC: 

34 NRC. NUREG-1437, Volume 1, Addendum 1. August 1999. ADAMS No. ML04069720.

35 [NRC] U.S. Nuclear Regulatory Commission. 2000. Environmental Standard Review Plan: 

36 Standard Review Plans for Environmental Reviews for Nuclear Power Plants. Washington, DC: 

37 NRC. NUREG-1555.

38 [NRC] U.S. Nuclear Regulatory Commission. 2008. South Texas Project Units 3 and 4 COL

39 Site Audit and Scoping Trip Report. February 3-8, 2008. ADAMS No. ML081010440.

40 [NRC] U.S. Nuclear Regulatory Commission. 2011a. E-mail from B Martin, THC, to TK O’Neil, 

41 PNNL. Subject: STP license renewal—SHPO meeting. May 2, 2011. ADAMS 

42 No. ML11259A029. 

43 [NRC] U.S. Nuclear Regulatory Commission. 2011b. Environmental Impact Statement for 

44 Combined Licenses (COLs) for South Texas Project Electric Generating Station, Units 3 and 4. 
Affected Environment

2-79

1 Washington, DC: NRC. NUREG-1937, Volumes 1 and 2. ADAMS Nos. ML11049A000 and 

2 ML11049A001.

3 [NRC] U.S. Nuclear Regulatory Commission. 2011c. Essential Fish Habitat Assessment for 

4 South Texas Project Electric Generating Station Units 3 and 4. Washington, DC: NRC. Final 

5 Report. ADAMS No. ML11049A001.

6 [NRC] U.S. Nuclear Regulatory Commission. 2011d. Letter from BM Pham, NRC, to DL Klima, 

7 Advisory Council on Historic Preservation. Subject: South Texas Project, Units 1 and 2, license 

8 renewal application review. January 27, 2011. ADAMS No. ML110200002.

9 [NRC] U.S. Nuclear Regulatory Commission. 2011e. Letter from BM Pham, NRC, to M Wolfe, 

10 Texas Historical Commission. Subject: South Texas Project, Units 1 and 2, license renewal 

11 application review (track no. 201002271). February 17, 2011. ADAMS No. ML110190549.

12 [NRC] U.S. Nuclear Regulatory Commission. 2011f. Letter from D Wrona, Branch Chief, to M 

13 Orms M, FWS. Subject: Request for concurrence on list of Federally protected species. 

14 February 16, 2011. ADAMS No. ML110190429.

15 [NRC] U.S. Nuclear Regulatory Commission. 2011g. Letter from T Tran, NRC, to GT Powell, 

16 STPNOC. Subject: Audit report regarding South Texas Project license renewal application—

17 cultural resources. July 18, 2011. ADAMS No. ML11173A304.

18 [NRCS] Natural Resources Conservation Service. 2011, “Web Soil Survey, Soil Map—

19 Matagorda County, Texas, Map Unit Description–Matagorda County, Texas.” April 12, 2011. 

20 Available at <http://websoilsurvey.nrcs.usda.gov/app> (accessed October 9, 2011).

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23 ELMR Reort No. 11. Silver Spring, MD: NOAA/NOS Strategic Environmental Assessments 

24 Division.

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30 Ryder, PD, Ardis, AF. 2002. Hydrology of the Texas Gulf Coast Aquifer Systems, Regional 

31 Aquifer-Systems Analysis-Gulf Coast Plain. Reston, VA: U.S. Geological Survey. U.S. 

32 Geological Survey Professional Paper 1416-E.

33 Santana FM, Lessa R, Carlson J. 2006. “Carcharhinus signatus.” Available at 

34 <http://www.iucnredlist.org/apps/redlist/details/60219/0> (accessed June 28, 2011).

35 [STPNOC] South Texas Project Nuclear Operating Company. 2007. 2006 Annual 

36 Environmental Operating Report, South Texas Project Electric Generating Station. Bay City, 

37 TX: STPNOC. April 2007. ADAMS No. ML071270211. 

38 [STPNOC] South Texas Project Nuclear Operating Company. 2008. Letter from Gregory

39 Gibson, STPNOC, to NRC Document Control Desk. Subject: Response to RAI. July 15, 2008,

40 No. ML082040684.

41 [STPNOC] South Texas Project Nuclear Operating Company. 2009a. Updated Final Safety 

42 Analysis Report Units 1 and 2. Bay City, TX: STPNOC. Revision 15. ADAMS No. 

43 ML103220222. 
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1 [STPNOC] South Texas Project Nuclear Operating Company. 2009b. Water Conservation 

2 Plan, STP Nuclear Operating Company, South Texas Project Electric Generating Station, 

3 Certificate of Adjudication 14-5437 A. May 1, 2009. Revision 2. ADAMS No. ML11256A058.

4 [STPNOC] South Texas Project Nuclear Operating Company. 2010a. 2009 Annual 

5 Environmental Operating Report, South Texas Project Electric Generating Station. Bay City, 

6 TX: STPNOC. April 2010. ADAMS No. ML101260530.

7 [STPNOC] South Texas Project Nuclear Operating Company. 2010b. South Texas Project, 

8 Units 1 and 2, License Renewal Application. Bay City, TX: STPNOC. Appendix E, 

9 “Environmental Report.” September 2010. ADAMS No. ML103010263.

10 [STPNOC] South Texas Project Nuclear Operating Company. 2010c. South Texas Project, 

11 Units 3 and 4, Combined License Application. Bay City, TX: STPNOC. Part 2, “Final Safety 

12 Analysis Report,” Revision 4. ADAMS No. ML102860517.

13 [STPNOC] STP Nuclear Operating Company. 2010d. South Texas Project, Units 3 and 4, 

14 Combined License Application. Bay City, TX: STPNOC. Part 3, “Environmental Report,” 

15 Revision 4. ADAMS No. ML102860592. 

16 [STPNOC] South Texas Project Nuclear Operating Company (STPNOC). 2010e. Letter from 

17 Mark McBurnett, STPNOC, to NRC Document Control Desk. Subject: Additional Information 

18 Regarding Draft Environmental Impact Statement. September 9, 2010. ADAMS 

19 No. ML102600127.

20 [STPNOC] South Texas Project Nuclear Operating Company. 2011a. 2010 Annual 

21 Environmental Operating Report, South Texas Project Electric Generating Station. Bay City,

22 TX: STPNOC. April 2011. ADAMS Nos. ML111250423 and ML111250429.

23 [STPNOC] South Texas Project Nuclear Operating Company. 2011b. Letter from AW Harrison, 

24 Manager Licensing, to NRC Document Control Desk. Subject: Transmittal of documents to 

25 support review of the STP LRA. TAC Nos. ME 4938 and ME 5122. STP Letter 

26 No. NOC-AE-11002720. August 31, 2011. ADAMS Nos. ML11256A056 and ML11256A059. 

27 [STPNOC] South Texas Project Nuclear Operating Company. 2011c. Letter from GT Powell, 

28 STPNOC, to NRC Document Control Desk. Subject: Response to RAI for the review of the 

29 STP LRA. July 5, 2011. ADAMS No. ML11193A016.

30 [STPNOC] South Texas Project Nuclear Operating Company. 2011d. Letter from GT Powell, 

31 Vice President, STPNOC, to NRC Document Control Desk. Subject: Response to RAI for the 

32 STP LRA. TAC Nos. ME4938 and ME5122. STP Letter No. NOC-AE-11002719. 

33 September 6, 2011. ADAMS No. ML11255A211.

34 [STPNOC] South Texas Project Nuclear Operating Company. 2011e. Letter from GT Powell, 

35 Vice President, STPNOC, NRC Document Control Desk. Subject: Response to RAI for the 

36 review of the STP LRA. TAC Nos. ME4938 and ME5122. STP Letter No. NOC-AE-11002723. 

37 September 12, 2011. ADAMS No. ML11259A014.

38 [STPNOC] South Texas Project Nuclear Operating Company. 2011f. Letter from GT Powell, 

39 STPNOC, to NRC Document Control Desk. Subject: Response to RAI for the review of the 

40 STP LRA. October 18, 2011. ADAMS No. ML11298A085. 

41 [STPNOC] South Texas Project Nuclear Operating Company. 2011g. Letter from GT Powell, 

42 Vice President, STPNOC, NRC Document Control Desk. Subject: response to RAI for the 

43 review of the LRA. July 5, 2011. ADAMS No. ML11193A074. 
Affected Environment

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1 [STPNOC] South Texas Project Nuclear Operating Company. 2012a. South Texas Project, 

2 Units 1 and 2, Clarification of Information. Bay City, TX: STPNOC. January 10, 2012. ADAMS 

3 No. ML12011A188.

4 [STPNOC] South Texas Project Nuclear Operating Company. 2012b. Letter from GT Powell, 

5 Vice President, STPNOC, NRC Document Control Desk. Subject: response to RAI for the 

6 review of the LRA. March 12, 2012. ADAMS No. ML12079A014. 

7 [TCEQ] Texas Commission on Environmental Quality. 2005. STPNOC TPDES Permit 

8 No. WQOOO 1908000, Permit to Discharge Wastes. July 21, 2005. ADAMS 

9 No. ML11256A057.

10 [TCEQ] Texas Commission on Environmental Quality. 2009. Letter from L Lancaster, Team 

11 Leader Application Review and Processing Team, TCEQ, to SL Dannhardt, STPNOC. Subject: 

12 Declaration of Administrative Completeness, STPNOC, Permit No. WQ0001908000 (EPA ID 

13 No. TX0064947) (RN102395654), Type of Authorization: Renewal. July 13, 2009. ADAMS 

14 No. ML11255A211.

15 [TCEQ] Texas Commission on Environmental Quality. 2011. “Draft 2010 Texas Integrated 

16 Report for Clean Water Act Sections 305(b) and 303(d).” March 8, 2011. Available at 

17 <http://www.tceq.texas.gov/waterquality/ assessment/10twqi/10twqi> (accessed 

18 October 20, 2011).

19 Texas Historical Commission. 2011. “Celebrate Native American Heritage in November.” 

20 Available at <http://www/thc/.state.tx.us/news/whatsnewstories/wnnamnth.shtml> (accessed 

21 October 28, 2011). 

22 Texas Water Code, Title 2, Water Administration, Chapter 36, Groundwater Conservation 

23 Districts. Available at <http://www.twdb.state.tx.us/gwrd/gcd/gcdhome.htm> (accessed 

24 July 2012).

25 [TMMSN] Texas Marine Mammal Stranding Network. 2011. “The Gulf of Mexico’s Marine 

26 Mammals.” January 2, 2011. Available at 

27 <http://www.sci.tamucc.edu/tmmsn/29Species/marine.html> (accessed May 19, 2011).

28 [TPWD] Texas Parks and Wildlife Department. 2011a. “Brazos Bend State Park.” Available at 

29 <http://www.tpwd.state.tx.us/spdest/findadest/parks/brazos_bend/> (accessed 

30 September 27, 2011).

31 [TPWD] Texas Parks and Wildlife Division. 2011b. “Jaguarundi.” Available at 

32 <http://www.tpwd.state.tx.us/publications/pwdpubs/media/pwd_bk_w7000_0013_jaguarundi.

33 pdf> (accessed September 7, 2011).

34 [TPWD] Texas Parks and Wildlife Division. 2011c. Letter from A Turner, Wildlife Habitat 

35 Assessment Program, to B Pham, Branch Chief, NRC. Subject: Reply to request for species 

36 list for South Texas license renewal. April 20, 2011. ADAMS No. ML11119A009.

37 [TPWD] Texas Parks and Wildlife Department. 2011d. “Mad Island.” Available at 

38 <http://www.tpwd.state.tx.us/huntwild/hunt/wma/find_a_wma/list/?id=39> (accessed 

39 September 27, 2011).

40 [TPWD] Texas Parks and Wildlife Division. 2011e. “Ocelot (Leopardus pardalis).” Available at 

41 <http://www.tpwd.state.tx.us/huntwild/wild/species/ocelot/> (accessed 7 September 2011).

42 [TPWD] Texas Parks and Wildlife Division. 2011f. “Rare, Threatened, and Endangered 

43 Species of Texas for Bexar, Brazoria, Colorado, DeWitt, Fayette, Gonzales, Guadalupe, 

44 Jackson, Lavaca, Matagorda, Wharton, and Wilson Counties.” Available at 
Affected Environment 

2-82

1 <http://gis.tpwd.state.tx.us/TpwEndangeredSpecies/DesktopDefault.aspx> (accessed 

2 May 19, 2011).

3 [TSHA] Texas State Historical Association. 2011. “Texas Almanac: Population History of 

4 Counties from 1850–2010.” Available at <http://www.texasalmanac.com/topics/population> 

5 (accessed January 2011).

6 [TSWGW] Texas Saltwater and Fishing Guides Web. 2005. “King Mackerel (Kingfish).” 

7 Available at <http://www.txsaltwaterfishingguides.com/FishFacts/kingfish.htm> (accessed 

8 September 9, 2011). ADAMS No. ML100600370.

9 [TWDB] Texas Water Development Board. 2006. Aquifers of the Gulf Coast of Texas. Austin, 

10 TX: TWDB. Report 365. February 2006. Available at 

11 <http://www.twdb.state.tx.us/publications/reports/GroundWaterReports/GWReports/R365/

12 AGCindex.htm> (accessed August 31, 2011).

13 [TWDB] Texas Water Development Board. 2007. State Water Plan—Water for Texas 2007. 

14 Austin, TX: TWDB Document No. GP-8-1. Volume 1. January 2007. Available at 

15 <http://www.twdb.state.tx.us/wrpi/swp/swp.asp> (accessed August 31, 2011).

16 [TXDOT] Texas Department of Transportation. 2011. “District Traffic Maps—2010.” Available 

17 at <http://ftp.dot.state.tx.us/pub/txdot-info/tpp/traffic_counts/2010/ykm_base.pdf> (accessed 

18 April 2011).

19 University of Texas at Austin. 2011. “Texas Beyond History.” Available at 

20 <http://www/texasbeyondhistory.net/faq/index.html#9> (accessed October 28, 2011). 

21 [USACE] U.S. Army Corps of Engineers. 2009. Letter from K Jaynes, Compliance 

22 Section Chief, Galveston District, to R Kiesling, STPNOC. Subject: Jurisdictional wetlands on 

23 the South Texas site. May 14, 2009. ADAMS No. ML11256A057.

24 [USCB] U.S. Census Bureau. 2010. “American FactFinder, Census 2000 and 2006–2008, 

25 3-Year Estimate, American Community Survey, State and County QuickFacts on Brazoria and 

26 Matagorada Counties. Housing Characteristics for 2000 and 2006-2008, 3-Year Estimate. 

27 Profile of Selected Economic Characteristics: 2000 and 2010.” Available at 

28 <http://factfinder.census.gov and http://quickfacts.census.gov> (accessed January 2011).

29 [USDA NASS] U.S. Department of Agriculture National Agricultural Statistics Service. 2009. 

30 “2007 Census of Agriculture, Volume 1, Chapter 2, Table 1 and Table 7.” December 2009. 

31 Available at 

32 <http://www.agcensus.usda.gov/Publications/2007/Full_Report/Volume_1,_Chapter_2_County_

33 Level/Texas/index.asp> (accessed June 2011).

34 [USGS] U.S. Geological Survey. 2008. “Geologic Hazards Team Interactive Map Server, 

35 National Seismic Hazard Maps—2008.” April 23, 2008. Available at <http://gldims.cr.usgs.gov> 

36 (accessed September 20, 2011).

37 [USGS] U.S. Geological Survey. 2011a. “Circular Area Earthquake Search, NEIC: Earthquake 

38 Search Results, U.S. Geological Survey Earthquake Database.” (search parameters: 

39 Significant U.S. Earthquakes (1569–1989) Database, Latitude 28.7951 N, Longitude -96.04900 

40 W, Radius 550 km). October 4, 2010. Available at 

41 <http://earthquake.usgs.gov/earthquakes/eqarchives/epic/epic_circ.php> (accessed 

42 September 20, 2011).

43 [USGS] U.S. Geological Survey. 2011b. “Circular Area Earthquake Search, NEIC: Earthquake 

44 Search Results, U.S. Geological Survey Earthquake Database.” (search parameters: 

45 USGS/NEIC (PDE) 1973 Database, Latitude 28.7951 N, Longitude -96.04900 W, Radius 
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1 200 km). October 4, 2010. Available at 

2 <http://earthquake.usgs.gov/earthquakes/eqarchives/epic/epic_circ.php> (accessed 

3 September 20, 2011).

4 [USGS] U.S. Geological Survey. 2011c. “Texas Earthquake Information, Seismicity Map of 

5 Texas, Seismic Hazard Map of Texas.” Available at 

6 <http://earthquake.usgs.gov/earthquakes/states/index.php?regionID=43> (accessed 

7 September 20, 2011).

8 [USGS] U.S. Geological Survey. 2011d. “USGS Surface-Water Annual Statistics for the 

9 Nation, USGS 08162500, Colorado River Near Bay City, TX.” Available at 

10 <http://waterdata.usgs.gov/nwis/annual/?referred_module=sw&site_no=08162500&por_

11 08162500_1=1460,00060,1,1948,2011&year_type=W&format=html_table&date_format=YYYY12 MM-DD&rdb_compression=file&submitted_form=parameter_selection_list> (accessed 

13 August 31, 2011).

14 Wai CN, Huntsman G. 2006a. “Epinephelus drummondhayi.” Available at 

15 <http://www.iucnredlist.org/apps/redlist/details/7854/0> (accessed June 28, 2011).

16 Wai CN, Huntsman G. 2006b. “Hyporthodus nigritus.” Available at 

17 <http://www.iucnredlist.org/apps/redlist/details/7860/0> (accessed June 28, 2011).

18 [WEG] Wild Earth Guardians. Petition to list the saltmarsh topminnow (Fundulus jenkinsi) under 

19 the U.S. Endangered Species Act. September 3, 2010. Available at 

20 <http://sero.nmfs.noaa.gov/pr/esa/Candiate%20Spp/Saltmarsh%20Topminnow%20Petition-1.

21 pdf> (accessed June 28, 2011).

22 Wiken E, Nava FJ, Griffith G. 2011. North American Terrestrial Ecoregions—Level III. 

23 Montreal, Canada: Commission for Environmental Cooperation. 149 p. Available at 

24 <ftp://ftp.epa.gov/wed/ecoregions/pubs/NA_TerrestrialEcoregionsLevel3_Final-2june11_CEC.

25 pdf> (accessed September 12, 2011).

26 Wilber, D. 1989. Reproductive biology and distribution of stone crabs (Xanthidae, menippe) in 

27 the hybrid zone on the northeastern Gulf of Mexico. Marine Ecology Progress 

28 Series 52(1989):235-244.

29 Young, SC, Kelly, V, Budge, T, Deeds, N. 2007. FINAL Development of the LSWP 

30 Groundwater Flow Model for the Chicot and Evangeline Aquifers in Colorado, Wharton, and 

31 Matagorda Counties. Austin, TX: URS Corporation, INTERA, and Baer Engineering and 

32 Consulting. Available at 

33 <http://www.lcra.org/library/media/public/docs/lswp/findings/URS_Mitigation_report_final.pdf>. 

34 ADAMS No. ML100471604.

3-1 

1 3.0 ENVIRONMENTAL IMPACTS OF REFURBISHMENT

2 Facility owners or operators may need to undertake or, for economic or safety reasons, may 

3 choose to perform refurbishment activities in anticipation of license renewal or during the license 

4 renewal term. The major refurbishment class of activities characterized in the Generic 

5 Environmental Impact Statement for License Renewal of Nuclear Plants (GEIS) (NRC 1996) is 

6 intended to encompass actions that typically take place only once in the life of a nuclear plant, if 

7 at all. Examples of these activities include, but are not limited to, replacement of boiling-water 

8 reactor recirculation piping and pressurized-water reactor steam generators. These actions 

9 may have an impact on the environment beyond those activities occurring during normal 

10 operations for which the activities require evaluation, depending on the type of action and the 

11 plant-specific design. Table 3–1 lists the environmental issues associated with refurbishment 

12 that the U.S. Nuclear Regulatory Commission (NRC) staff (the staff) determined to be 

13 Category 1 issues in the GEIS.

14 Table 3–1. Category 1 Issues Related to Refurbishment 

15

Issue GEIS Section(s)

Surface water quality, hydrology, and use (for all plants)

Impacts of refurbishment on surface water quality 3.4.1

Impacts of refurbishment on surface water use 3.4.1

Aquatic ecology (for all plants)

Refurbishment 3.5

Groundwater use and quality

Impacts of refurbishment on groundwater use and quality 3.4.2

Land use

Onsite land use 3.2

Human health

Radiation exposures to the public during refurbishment 3.8.1

Occupational radiation exposures during refurbishment 3.8.2

Socioeconomics

Public services: public safety, social services, and tourism and

recreation 3.7.4; 3.7.4.3; 3.7.4.4; 3.7.4.6

Aesthetic impacts (refurbishment) 3.7.8

Table source: Table B–1 in Appendix B, Subpart A, to 10 CFR Part 51

16

17 Table 3–2 lists environmental issues related to refurbishment that the NRC staff determined to 

18 be plant-specific or inconclusive in the GEIS. These issues are Category 2 issues. The 
Environmental Impacts of Refurbishment

3-2 

1 definitions of Category 1 and 2 issues can be found in Section 1.4 of this supplemental 

2 environmental impact statement (SEIS). 

3 Table 3–2. Category 2 Issues Related to Refurbishment

Issue GEIS Section(s) 10 CFR 51.53(c)(3)(ii) 

Subparagraph

Terrestrial resources

Refurbishment impacts 3.6 E

Threatened or endangered species (for all plants)

Threatened or endangered species 3.9 E

Air quality

Air quality during refurbishment

(non-attainment and maintenance areas) 3.3 F 

Socioeconomics

Housing impacts 3.7.2 I 

Public services: public utilities 3.7.4.5 I

Public services: education (refurbishment) 3.7.4.1 I

Offsite land use (refurbishment) 3.7.5 I

Public services, transportation 3.7.4.2 J

Historic and archaeological resources 3.7.7 K

Environmental justice

Environmental justice(a) Not addressed Not addressed

(a) Guidance related to environmental justice was not in place at the time the NRC prepared the GEIS and the 

associated revision to 10 CFR Part 51. If an applicant plans to undertake refurbishment activities for license 

renewal, the applicant’s Environmental Report (ER) and the staff’s SEIS must address environmental justice.

Table source: Table B–1 in Appendix B, Subpart A, to 10 CFR Part 51

 4 

5 Table B.2 of the GEIS identifies systems, structures, and components (SSCs) that are subject to 

6 aging and might require refurbishment to support continued operation during the license 

7 renewal period of a nuclear facility. In preparation for its license renewal application, South 

8 Texas Project Nuclear Operating Company (STPNOC) performed an evaluation of these SSCs 

9 pursuant to Section 54.21 of Title 10, Energy, of the Code of Federal Regulation (10 CFR 54.21) 

10 to identify the need to undertake any major refurbishment activities that would be necessary to 

11 support the continued operation of South Texas Project (STP) during the proposed 20-year 

12 period of extended operation.

13 In the ER, STPNOC indicated that, in accordance with 10 CFR Part 54, STPNOC has submitted 

14 an integrated plant assessment (IPA) addressing the aging management of SSC for license 

15 renewal. The IPA does not identify the need to undertake any major refurbishment activities 

16 that are necessary to support continued operation of STP during the period of extended 
Environmental Impacts of Refurbishment

3-3 

1 operation (STPNOC 2010). Furthermore, STPNOC indicated that it has replaced the steam 

2 generator and reactor heads to meet the operational needs under the current license. 

3 Therefore, the staff does not assess refurbishment activities in this SEIS.

5 10 CFR Part 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental 

6 protection regulations for domestic licensing and related regulatory functions.”

4 3.1 References

7 10 CFR Part 54. Code of Federal Regulations, Title 10, Energy, Part 54, “Requirements for 

8 renewal of operating licenses for nuclear power plants.”

9 [NRC] U.S. Nuclear Regulatory Commission. 1975. Final Environmental Statement Related to 

10 The Proposed South Texas Project, Units 1 and 2. Washington, DC: NRC. NUREG-75/019. 

11 March 1975. ADAMS No. ML11174A118

12 [NRC] U.S. Nuclear Regulatory Commission. 1996. Generic Environmental Impact Statement 

13 for License Renewal of Nuclear Plants. Washington, DC: NRC. NUREG-1437. May 1996. 

14 ADAMS Nos. ML040690705 and ML040690738.

15 [NRC] U.S. Nuclear Regulatory Commission. 1999. Section 6.3, Transportation, Table 9.1, 

16 Summary of findings on NEPA issues for license renewal of nuclear power plants. In: Generic 

17 Environmental Impact Statement for License Renewal of Nuclear Plants. Washington, DC: 

18 NRC. NUREG-1437, Volume 1, Addendum 1. August 1999. ADAMS No. ML04069720.

19 [STPNOC] South Texas Plant Nuclear Operating Company. 2010b. “South Texas Project, 

20 Applicant’s Environmental Report—Operating License Renewal Stage, South Texas Project

21 Units 1 & 2.” September 2010. ADAMS No. ML103010263. 

4-1 

1 4.0 ENVIRONMENTAL IMPACTS OF OPERATION

2 This chapter addresses potential environmental impacts related to the period of extended 

3 operation of South Texas Project (STP). These impacts are grouped and presented according 

4 to resource. Generic issues (Category 1) rely on the analysis presented in the Generic 

5 Environmental Impact Statement (GEIS) for License Renewal of Nuclear Plants

6 (NRC 1996, 1999). Site-specific issues (Category 2) have been analyzed for STP. However,

7 some issues are not applicable to STP because of site characteristics or plant features. 

8 Section 1.4 of this supplemental environmental impact statement (SEIS) provides an 

9 explanation of the criteria for Category 1 and Category 2 issues, as well as the definitions of 

10 SMALL, MODERATE, and LARGE.

4.1

12 Onsite land use issues that could be affected by license renewal are listed in Table 4–1. As 

13 discussed in the GEIS, onsite land use and powerline right-of-way conditions are expected to 

14 remain unchanged during the license renewal term at all nuclear plants; thus, impacts would be 

15 SMALL. These issues, therefore, were classified as Category 1 issues. Section 2.2.1 of this 

16 SEIS describes the land use conditions at STP.

11 Land Use

17 The NRC staff reviewed and evaluated South Texas Project Nuclear Operating Company’s 

18 (STPNOC’s) Environmental Report (ER) (STPNOC 2010b), scoping comments, and other 

19 available data on STP, Units 1 and 2, were reviewed and evaluated for new and significant 

20 information. The review included an audit conducted by the NRC staff at the STP site. No new 

21 and significant information was identified during this review that would change the conclusions 

22 presented in the GEIS. Therefore, for these Category 1 issues, impacts during the renewal term 

23 are not expected to exceed those discussed in the GEIS.

24 Table 4–1. Land Use Issues

4.2

26 Section 2.2.2 of this SEIS describes the meteorology and air quality in the vicinity of the STP 

27 site.

25 Air Quality

28 The air quality issue applicable to STP during the renewal term is discussed below and listed in 

29 Table 4–2. The GEIS did not identify any Category 2 issues related to air quality. The NRC 

30 staff did not identify any new and significant information during the review of the applicant’s ER 

31 (STPNOC 2010), the staff’s site audit, the scoping process, or the evaluation of other available 

32 information. Therefore, there are no impacts related to these issues beyond those discussed in 

33 the GEIS. For these issues, the GEIS concluded that the impacts are SMALL, and additional 

34 site-specific mitigation measures are unlikely to be sufficiently beneficial to warrant 

35 implementation.

Issue GEIS Section Category

Onsite land use 4.5.3 1

Powerline right-of-way 4.5.3 1

Source: Table B–1 in Appendix B, Subpart A, to 10 CFR Part 51
Environmental Impacts of Operation

4-2 

1 Table 4–2. Air Quality Issues

4.3

3 The surface water use, hydrology, and surface water quality issues potentially applicable to 

4 STP, Units 1 and 2, are discussed in the following sections and listed in Table 4–3. Surface 

5 water-related aspects and conditions relevant to STP, Units 1 and 2, are described in 

6 Sections 2.1.7.1 and 2.2.4 of this SEIS.

2 Surface Water Resources

7 Table 4–3. Surface Water Resources Issues

8 4.3.1 Generic Surface Water Issues

9 NRC did not identify any new and significant information with regard to Category 1 (generic) 

10 surface water issues based on review of the ER (STPNOC 2010b), the public scoping process, 

11 or as a result of the environmental site audit. The NRC staff also reviewed other sources of 

12 information such as various permits and data reports. As a result, no information or impacts 

13 related to these issues were identified that would change the conclusions presented in the 

14 GEIS. Therefore, it is expected that there would be no impacts related to these Category 1 

15 issues during the renewal term beyond those discussed in the GEIS. For these surface water 

16 issues, the GElS concludes that the impacts are SMALL.

17 4.3.2 Surface Water Use Conflicts—Plants Using Makeup Water from a Small River with 

18 Low Flow 

19 For nuclear power plants using cooling towers or cooling ponds that are supplied with makeup 

20 water from a small river, the potential impact on the flow of the river and related impacts on 

21 instream and riparian ecological communities is considered a Category 2 issue; thus, it requires 

22 a plant-specific assessment. The requirement for this assessment is specified by 

23 10 CFR 51.53(c)(3)(ii)(A), which also defines a small river as one whose annual flow rate is less 

than 3.15x1012 ft3

/yr (9x1010 m3/yr) or 100,000 cfs (2,820 m3 24 /s). STP, Units 1 and 2, has a 

Issue GEIS Section Category

Air quality effects of transmission lines 4.5.2 1

Source: Table B–1 in Appendix B, Subpart A, to 10 CFR Part 51

Issues GEIS Section Category

Altered current patterns at intake & discharge structures 4.2.1.2.1 1

Altered salinity gradients 4.2.1.2.2 1

Discharge of chlorine or other biocides 4.2.1.2.4 1

Discharge of sanitary wastes & minor chemical spills 4.2.1.2.4 1 

Discharge of other metals in wastewater 4.2.1.2.4 1 

Water use conflicts (plants with cooling towers & cooling ponds using 

makeup water from a small river with low flow) 4.3.2.1 2 

Source: STPNOC 2010b, 2011b and Table B–1 in Appendix B, Subpart A, to 10 CFR Part 51
Environmental Impacts of Operation

4-3 

1 closed-cycle heat-dissipation system that uses a cooling pond, the main cooling reservoir 

2 (MCR), with makeup water supplied from a small river, the lower Colorado River, with a mean 

annual discharge equivalent to 82.6x109 ft3

/yr (23.4x108 m3/yr) or 2,620 cfs (74.1 m3 3 /s). 

4 Therefore, an assessment of the impact of the proposed action on the flow of the river is 

5 required.

6 In the State of Texas, water use is regulated by the Texas Water Code. Surface water belongs 

7 to the State (Water Code, Title 2, Subtitle B, Chapter 11, Section 11.021). The right to use 

8 surface waters of the State can be acquired in accordance with the provisions of the Texas 

9 Water Code, Chapter 11. Because the Colorado River Basin is currently heavily appropriated

10 (used or obligated for use), future water users in this basin would likely obtain surface water by 

11 purchasing or leasing existing appropriations. The Texas Water Development Board (TWDB) 

12 uses 16 planning regions, the Regional Water Planning Areas (or regions), to plan and finance 

13 water supply projects. The regions prepare plans within their areas that are compiled into the 

14 State Water Plan. The most recent plan was adopted by the TWDB in November 2006 

15 (TWDB 2007). For this SEIS, the staff reviewed the best available information for its analysis. 

16 Currently, the State of Texas is in the 2011 to 2016 planning cycle. The regions have compiled 

17 the 2011 Regional Water Plans. The 2012 State Water Plan has been released for public 

18 comment (TWDB 2011). The STP site is located in the Lower Colorado Regional Water 

19 Planning Group (LCRWPG), or Region K. 

20 STPNOC owns water rights from the lower Colorado River to operate power reactors on the 

21 STP site. The waters of the Colorado River for STPNOC’s use are adjudicated (administered or 

22 allotted) via a water right secured in 1989 (STPNOC 2010b). An agreement between the Lower 

23 Colorado River Authority (LCRA) and STPNOC specifies the conditions related to STPNOC’s 

24 withdrawal (diversion) of water from the Colorado River. STPNOC is allowed to withdraw 

102,000 ac-ft/yr (126 million m3 25 /yr) from the Colorado River at a maximum withdrawal rate of 

1,200 cfs (34.4 m3 26 /s) or 540,000 gpm. However, STPNOC is limited to withdrawing 55 percent

of the river flow that exceeds 300 cfs (8.5 m3 27 /s) or 135,000 gpm (STPNOC 2009a; 

28 TCEQ 2009a). In other words, STPNOC is limited in its ability to withdraw water from the 

29 Colorado River during low flow conditions (i.e., 55 percent of the river flow at the volumetric flow 

30 rate that exceeds 300 cfs).

31 STPNOC’s historical withdrawals of surface water from the Colorado River for plant operations 

32 are summarized in Table 4–4. 

33
Environmental Impacts of Operation

4-4 

1 Table 4–4. Surface Water Withdrawals and Usage for Calendar Years 2003–2010 

2 for STP, Units 1 and 2

Calendar Year Water Withdrawal (ac-ft) (a) Water Use (ac-ft)

2003 0 27,800

2004 62,374 37,963

2005 5,694 35,383

2006 50,012 37,912

2007 58,740 39,403

2008 10,303 38,186

2009 72,464 38,008

2010 43,213 37,893

(a) To convert ac-ft to m3

, multiply by 1,233.5. To convert ac-ft to gal, multiply by 325,851. 

Source: STPNOC 2010b, 2011b 

Between 2003 and 2010, STPNOC withdrew an average of 37,850 ac-ft/yr (46.7 million m3 3 /yr) 

from the Colorado River and consumed an average of 36,569 ac-ft/yr (45.1 million m3 4 /yr) to 

5 support the operations of STP, Units 1 and 2. For a given year, withdrawals from the lower 

6 Colorado River can be significantly less or more than corresponding water use because of rules 

7 for water withdrawal specified in the LCRA–STPNOC contract (right to purchase or use), which

8 are based on river flow and meteorological conditions that affect evaporation from the MCR. In 

9 2003, STPNOC withdrew no water from the Colorado River but consumptively used 27,800 ac-ft 

(34.3 million m3

). The following year, STPNOC had to withdraw 62,374 ac-ft (76.9 million m3 10 ) of 

river water to cover the 37,963 ac-ft (46.8 million m3 11 ) of consumption and to replenish the MCR 

12 storage (the MCR functions and specifications are described in Section 2.1.6). The average, 

13 minimum, and maximum yearly withdrawals from the lower Colorado River over the 

14 2003 to 2010 period are 36, 0, and 71 percent of the STPNOC annual water rights of 

102,000 ac-ft (126 million m3 15 ).

16 The LCRWPG adopted its 2011 Region Plan in July 2010 (LCRWPG 2010). The LCRWPG 

17 estimated that the total water demand in Region K would increase from 1,086,692 ac-ft/yr 

(1.34 billion m3

/yr) in 2010 to 1,382,534 ac-ft/yr (1.71 billion m3 18 /yr) in 2060, mainly due to a 

19 projected doubling of the population of Region K over the timeframe. The LCRWPG estimated 

that the water available to Region K would decline from 1,331,715 ac-ft/yr (1.64 billion m3 20 /yr) in 

2010 to 1,289,453 ac-ft/yr (1.59 billion m3 21 /yr) in 2060. The LCRWPG estimated that region-wide 

water shortages would be 297,000 and 367,000 ac-ft/yr (366 and 453 million m3 22 /yr) in 2030 and 

23 2060, respectively (LCRWPG 2010). To estimate shortages, the LCRWPG used the following 

24 conservative assumptions: 

25 • Available water would be that during a historical drought of record. 

26 • All water rights would be used fully and simultaneously. 

27 • Interruptible water from LCRA and municipal return flows to the Colorado 

28 River would not be available. 

29 These assumptions are conservative because they minimize water availability and maximize 

30 water use, thereby maximizing potential shortages.
Environmental Impacts of Operation

4-5 

1 The region plans to address shortages by using a variety of strategies. These water 

2 management strategies include use of municipal return flows, conservation, reuse, new water 

3 storage facilities, aquifer storage of surface water, new groundwater supply development, 

4 saltwater desalination, and intra-region transfer of water from areas with surplus. The LCRWPG 

5 estimated that the implementation of all water management strategies could yield an additional 

349,862 to 610,750 ac-ft/yr (432 to 754 million m3 6 /yr) to meet the estimated shortages 

7 (LCRWPG 2010).

8 During the past 5 years, withdrawals from the lower Colorado River to support the operations of 

STP, Units 1 and 2, have averaged 46,946 ac-ft/yr (57.9 million m3 9 /yr), which is equivalent to 

2.5 percent of the mean annual discharge of 2,620 cfs (74.1 m3 10 /s) or approximately 

1.89 million ac-ft/yr (2.3 billion m3 11 /yr) for the river. The average withdrawal for STP, Units 1 

12 and 2, is 3.5 and 3.6 percent of the water available to Region K in 2010 and 2060, respectively. 

13 The 2060 projection is based on the assumption that no implementation of any strategies to 

14 augment (or to change) regional water supply would have taken place. STPNOC’s water right 

of 102,000 ac-ft/yr (126 million m3 15 /yr) is accounted for in the Region K plan. The LCRWPG has 

16 evaluated several strategies that can be used to meet shortages that may occur during 

17 conditions similar to the drought of record when all existing water rights are fully and 

18 simultaneously used. Therefore, NRC concludes that continued operation of STP, Units 1 

19 and 2, as supported by the currently held water rights, would have no substantial effect on water 

20 supplies in the region. NRC further concludes that the impact on surface water resources and 

21 downstream water availability in the lower Colorado River from continued withdrawals during the 

22 license renewal term would be SMALL.

4.4

24 The groundwater use and quality issues applicable to STP, Units 1 and 2, are discussed in the 

25 following sections and listed in Table 4–5 for Category 1 (generic) and Category 2 (site-specific) 

26 issues. Groundwater resources-related aspects and conditions relevant to STP, Units 1 and 2, 

27 are described in Sections 2.1.7.2 and 2.2.5 of this SEIS.

23 Groundwater Resources

28 Table 4–5. Groundwater Resources Issues

Issues GEIS Section Category

Groundwater use conflicts (potable and service water & dewatering; 

plants that use >100 gpm) 4.8.1.1, 4.8.1.2 2 

Groundwater use conflicts (plants using cooling towers withdrawing 

makeup water from a small river) 4.8.1.3 2 

Groundwater quality degradation (saltwater intrusion) 4.8.2.1 1

Groundwater quality degradation (cooling ponds in salt marshes) 4.8.3 1

29 4.4.1 Generic Groundwater Issues

30 Section 2.2.5 of this SEIS discusses groundwater use and quality at STP. NRC did not identify 

31 any new and significant information with regard to Category 1 (generic) groundwater issues 

32 based on review of the ER (STPNOC 2010b), the public scoping process, or as a result of the 

33 environmental site audit. The NRC staff also reviewed other sources of information, such as 

34 applicable permits and data reports, as listed in the reference section of this SEIS chapter. The 

35 staff provides a list of STP permits for operation (status of compliance) in Appendix C. As a 
Environmental Impacts of Operation

4-6 

1 result, no information or impacts related to these issues were identified that would change the 

2 conclusions presented in the GEIS. Therefore, it is expected that there would be no impacts 

3 related to these Category 1 issues during the renewal term beyond those discussed in the

4 GEIS. For these groundwater issues, the GElS concludes that the impacts are SMALL.

5 4.4.2 Groundwater Use Conflicts

6 This section presents the NRC staff’s review of plant-specific (Category 2) groundwater use 

7 conflict issues, as listed in Table 4–5. 

8 4.4.2.1 Plants Using Greater Than 100 gpm of Groundwater

9 For nuclear power plants that pump more than 100 gpm (380 L/min) of groundwater from onsite 

10 wells, the potential groundwater use conflict with nearby groundwater users is considered a 

11 Category 2 issue that requires a plant-specific assessment, as specified in 

12 10 CFR 51.53(c)(3)(ii)(C).

13 As described in Section 2.1.7.2, onsite groundwater production at STP has averaged 768 gpm

(2,910 L/min) or 1,239 ac-ft/yr (1.5 million m3 14 /yr) annually over the 10-year period from 2001 

15 through 2010. STP has a permit for five production wells completed in the Deep Chicot Aquifer 

16 to withdraw at a combined rate of approximately 1,860 gpm (7,040 L/min) or 3,000 ac-ft/yr 

(3.7 million m3 17 /yr). Of the five production wells, wells 5, 6, and 7 (as described in 

18 Section 2.1.7.2) feed a common header (a single collection point) that delivers water to be 

19 chlorinated, filtered, and stored for use by the service water system and the fire protection 

20 system. Each of these three wells has a design capacity of 500 gpm (1,890 L/min) at a depth of 

21 700 ft (210 m). The service water system includes the demineralizer system and the potable 

22 water supply for the plant. The common header supplied by the three production wells is also 

23 the primary source for makeup water to the essential cooling pond (ECP). Well 8, with a design 

24 capacity of 250 gpm (950 L/min) at a depth of 600 ft (180 m), supplies the Nuclear Support 

25 Center chill water for the building cooling tower. The Nuclear Training Facility (NTF) well, with a 

26 design capacity of 200 gpm (760 L/min) and a depth of 600 ft (180 m), provides fire protection 

27 water to the NTF (STPNOC 2010b).

28 Because the annual average withdrawal rate from these sources for service water and fire 

29 protection water is greater than 100 gpm (380 L/min), this is a Category 2 issue for the STP site. 

30 All five STP production wells (5, 6, 7, 8, and NTF) are located relatively near the STP site 

31 boundary, as shown in Figure 2–1. Coastal Plains Groundwater Conservation District (CPGCD) 

32 rules require that wells of 7-in. (18-cm) diameter or greater completed on adjacent lands with 

33 different owners must be spaced a minimum of 2,500 ft (760 m) from any other permitted or 

34 registered well (CPGCD 2010). Therefore, drawdown at 2,500 ft (760 m) well spacing is 

35 relevant to the evaluation of potential conflicts with neighboring wells.

36 The applicant performed an analysis of drawdown using the Theis non-equilibrium well 

37 equations (E.E. Johnson, Inc. 1966). Using representative hydraulic properties, the applicant 

38 calculated drawdowns of 20.0 and 20.7 ft (6.1 and 6.3 m) in the Deep Chicot Aquifer after 

39 40 and 60 years, respectively, for a neighboring well located 2,500 ft (760 m) from an STP 

40 production well pumped at 500 gpm (1,890 L/min) (STPNOC 2011c). The projected change in 

41 drawdown during the additional 20 years of operation is less than 1 ft (0.3 m). The NRC staff 

42 checked and confirmed the applicant’s drawdown estimates, as presented in Table 4–6. To 

43 more completely evaluate the potential change in drawdown, the NRC staff also calculated 

44 drawdown at distances of 1 and 5 mi (1.6 and 8 km).

45
Environmental Impacts of Operation

4-7 

1 Table 4–6. Projected Drawdown and Change in Drawdown in Feet 

2 for the Deep Chicot Aquifer for Selected Distances

Distance (a)

Aquifer Drawdown ft (m) Change in Drawdown 

ft (m) 40 years 60 years

2,500 ft (760 m) 20 ft (6.1 m) (b) 20.7 ft (6.3 m) (b) 0.7 ft (0.2 m)

1 mi (1.6 km) 17.4 ft (5.3 m) 18.1 ft (5.5 m) 0.7 ft (0.2 m)

5 mi (8 km) 11.8 ft (3.6 m) 12.5 ft (3.8 m) 0.7 ft (0.2 m)

(a) All projections assume a saturated hydraulic conductivity of 33,245 gallons per day per foot (gpd/ft), coefficient of 

storage of 0.00022 (dimensionless), and a pumping rate of 500 gpm (1,890 L/min).

(b) This is based on STPNOC 2011c. Remaining drawdown values are based on NRC staff analyses. 

3 The STP ER for proposed Units 3 and 4 reproduced a map showing the potentiometric surface 

4 (the water level that would rise in a well) in the Deep Aquifer in Matagorda County in 1967 

5 (STPNOC 2010c). It shows the potentiometric head (hydraulic pressure) to be between 0 and 

6 10 ft (3 m) below mean sea level (MSL) at the STP site. The Deep Aquifer potentiometric 

7 surface in 2005 reveals the potentiometric head on the site boundary near wells 5 and 6 to be 

8 as great as 55 ft (17 m) below MSL. Well 5 was completed in 1975, and well 6 was completed 

9 in 1977. By 2005, these wells had been in service for approximately 30 years, and drawdown 

10 was approximately 50 ft (15 m) below MSL. Piezometers completed in the Deep Chicot Aquifer 

11 at the site (STPNOC 2010c) indicate a steady response pumping activity since the late 1990s, 

12 with one piezometer relatively near production well 5 showing a near constant piezometric head 

13 of 50 ft (15 m) below MSL. The elevation of the upper surface of the Deep Chicot Aquifer is 

14 between 250 to 300 ft (76 to 91 m) below ground surface or approximately 220 to 270 ft

15 (67 to 83 m) below MSL. Thus, the steady drawdown observed at the site ensures ample 

16 confining pressure remains in the Deep Chicot Aquifer. The drawdown observed suggests that 

17 a well located near the STP site boundary and one of the STP production wells could require a 

18 pumping lift (differential pressure applied by a pump) of approximately 50 ft (15 m) over 

19 conditions in 1967. This is the additional vertical distance that water would have to be pumped 

20 to the surface. However, the majority of this drawdown and associated pumping lift has been 

21 identified as regional drawdown resulting from groundwater development to the north of the STP 

22 site, as reflected in historical well and piezometer water well mapping (STPNOC 2009c).

23 The NRC staff’s analysis of drawdown using representative hydraulic properties and review of 

24 field data reveals that drawdown near STP production wells could influence the pumping lift of 

25 groundwater wells on neighboring properties. However, the drawdown at STP production wells 

26 from 40 years of pumping is estimated to be approximately 20 ft (6.1 m), and continued 

27 operation for an additional 20 years beyond the current license period would increase drawdown 

28 by less than 1 ft (0.3 m). This finding is influenced by local and regional groundwater use 

29 regulation as discussed above and in Section 2.2.5. The projected increase in drawdown of

30 less than 1 ft (0.3 m) is a negligible impact on neighboring wells and landowners. Therefore, the 

31 NRC staff concludes that groundwater use conflicts from STP groundwater withdrawals during 

32 the license renewal term would be SMALL. 

33 4.4.2.2 Plants Using Cooling Towers or Cooling Ponds and Withdrawing Makeup Water 

34 from a Small River

35 Nuclear power plants using cooling towers or cooling ponds that are supplied with makeup 

36 water from a small river (as defined in Section 4.3.2) require a plant-specific assessment due to 

37 the potential impact on alluvial aquifers. The requirement for this assessment is specified by 
Environmental Impacts of Operation

4-8 

1 10 CFR 51.53(c)(3)(ii)(A). This potential impact to groundwater is considered a Category 2 

2 issue. The GEIS established this groundwater aspect as Category 2 because consumptive use 

3 of water withdrawn from a small river could adversely affect groundwater aquifer recharge. Low 

4 river flow conditions are of particular interest.

5 STP, Units 1 and 2, is dependent on the lower Colorado River as the primary water source for 

6 the 7,000-ac (2,830-ha) MCR. Systems that have a groundwater source (e.g., service water, 

7 fire protection) also discharge to the MCR. The lower Colorado River meets the NRC definition 

8 of a small river. As noted in Section 2.2.5.1, the Shallow Chicot Aquifer discharges to the 

9 Colorado River southeast of the STP site. There is a relatively narrow band of an alluvial 

10 aquifer separating the Shallow Chicot Aquifer from the Colorado River. With the rise and fall of 

11 the Colorado River, the alluvial aquifer experiences bank storage. This refers to a condition 

12 such that when groundwater in the alluvial aquifer is higher than the river stage, the alluvial 

13 aquifer discharges to the river. Similarly, when river stage is higher than groundwater in the 

14 alluvial aquifer, the alluvial aquifer is recharged by the river. In general, the lower Colorado 

15 River is a gaining stream (sustained by groundwater discharges) near the STP site. This is 

16 because the Shallow Chicot Aquifer discharges to the alluvial aquifer, and the alluvial aquifer 

17 discharges to the Colorado River. During high river stage and local to the river shore, the 

18 groundwater elevation would increase in the alluvial and Shallow Chicot Aquifer, resulting in 

19 recharge to the aquifers. During low river stage, the Shallow Chicot Aquifer and the alluvial 

20 aquifer would resume discharging to the river.

21 Near the STP site, the Shallow Chicot Aquifer is used primarily for livestock watering because of 

22 its low yields to wells and relatively poor quality. The Deep Chicot Aquifer is separated 

23 hydraulically from the Shallow Chicot Aquifer by a 100- to 150-ft (30- to 46-m) thick confining 

24 unit, and it is the primary source of groundwater for the region due to high aquifer yields and 

25 good quality.

26 STPNOC is limited in its ability to divert water from the lower Colorado River during periods of 

27 low flow and can do so only after confirming the Colorado River flow at the U.S. Geological 

28 Survey (USGS) Bay City gaging station supports the withdrawal of surface water in accordance 

29 with STPNOC’s Certificate of Adjudication for water use, as discussed in Section 2.1.7.1 and

30 Section 4.3.2 (STPNOC 2009d, 2010b).

31 In summary, the following staff findings are relevant to the issue of groundwater use conflicts on 

32 alluvial aquifers from STP continued operations: 

33 • The alluvial aquifer is limited to a relatively narrow band between the 

34 Colorado River and the Shallow Chicot Aquifer. 

35 • The Colorado River is normally a gaining stream with the alluvial aquifer and 

36 Shallow Chicot Aquifer discharging to the river. During periods of low river 

37 flow, the alluvial aquifer and Shallow Chicot Aquifer would discharge to the 

38 river (the normal situation for a gaining stream). 

39 • The Shallow Chicot Aquifer is used for watering livestock and other low-yield, 

40 poor-quality applications and would not be substantially influenced by the 

41 bank storage effects of alluvial aquifer recharge and discharge. 

42 • The Deep Chicot Aquifer is the primary groundwater supply in the region, and 

43 it discharges to the lower Colorado River estuary and Matagorda Bay 

44 approximately 5 mi (8 km) downstream of STP (discussed in Section 2.2.5). 
Environmental Impacts of Operation

4-9 

1 • STP is limited through its Certificate of Adjudication and management plan 

2 regarding diversion of lower Colorado River water during low flow (discussed 

3 in Section 2.1.7.1 and Section 4.3.2). 

4 Based on the information above, the NRC staff concludes that continued withdrawals of surface 

5 water (the Colorado River) for the operation of STP, Units 1 and 2, during low-flow periods 

6 would have a SMALL impact on recharge to the alluvial aquifer during the license renewal term.

7 4.4.3 Groundwater Quality

8 As described in Section 4.4.1, the NRC staff did not identify any new and significant information 

9 with regard to Category 1 (generic) groundwater issues. As part of its assessment, the staff

10 specifically reviewed information relating to the current state of knowledge regarding 

11 groundwater quality downgradient of the MCR and underlying the STP protected area, as 

12 summarized below.

13 Elevated concentrations of tritium have been observed in groundwater adjacent to the MCR and 

14 in groundwater underlying the protected area of STP, Units 1 and 2, as described in 

15 Section 2.2.5.2. The MCR is unlined and water from the reservoir seeps into the Upper Shallow 

16 Aquifer. Systems within the protected area have released liquids containing tritium to 

17 groundwater.

18 Regarding non-radioactive contaminants in the MCR, total dissolved solids (TDS) is an indicator 

19 contaminant. The NRC staff anticipates that seepage from the MCR to the Upper Shallow 

20 Aquifer would initially have the same TDS concentration as the MCR. STPNOC’s estimate of 

21 the median TDS concentration in the MCR from operation of STP, Units 1 and 2, is 

22 approximately 2,000 mg/L (NRC 2011b). Locally, groundwater from the Shallow Aquifer is 

23 described as being slightly saline because TDS concentrations are above 1,000 mg/L 

24 (i.e., slightly saline waters have TDS ranges of 1,000 to 3,000 mg/L). Onsite wells completed in 

25 the Shallow Chicot Aquifer have an average TDS concentration of 1,200 mg/L 

26 (STPNOC 2010c). Accordingly, the Shallow Aquifer is used locally to water livestock, and it is 

27 not a freshwater supply. The NRC staff concludes that given a long-term local increase of TDS 

28 concentration to 2,000 mg/L, the groundwater TDS concentration would remain in the range 

29 associated with slightly saline waters. Thus, the potential future TDS level is consistent with the 

30 existing groundwater quality and its current use as a source of water for livestock. Any impacts 

31 from this change in groundwater quality would be localized because the groundwater plumes 

32 originating from the MCR are local to the STP site and the region immediately downgradient of 

33 the site to the lower Colorado River.

34 Regarding radioactive contaminants in the MCR, tritium is an indicator contaminant. Tritium 

35 releases occur to the Upper Shallow Chicot Aquifer from the MCR via seepage through the 

36 reservoir floor. Historical monitoring data for the MCR water (inside the MCR) show a peak 

37 tritium concentration of 17,410 picocuries per liter (pCi/L) in 1996 and values less than 

38 14,000 pCi/L since then (STPNOC 2010b, 2010c). A relief well monitored since 1995 showed a 

39 peak tritium concentration of 7,672 pCi/L in 1998 and values less than 7,000 pCi/L since then. 

40 Tritium activity in an onsite monitoring well completed in the Shallow Chicot Aquifer shows a 

41 peak in year 2000 of approximately 8,000 pCi/L and lower values before and after (NRC 2011b). 

42 Monitoring shows that levels of tritium in the Shallow Chicot Aquifer around the MCR originate 

43 from the liquids discharged to the MCR and are below the EPA primary drinking water standard 

44 (DWS) of 20,000 pCi/L (40 CFR Part 141). The staff also concludes that tritium concentrations 

45 in the Shallow Chicot Aquifer, resulting from seepage from the MCR, are bounded by the tritium 

46 concentration in the MCR waters. Thus, the observed peak tritium concentration of 
Environmental Impacts of Operation

4-10

1 17,410 pCi/L, and more recent levels of 14,000 pCi/L, ensures that tritium concentrations in 

2 groundwater downgradient of the MCR will be below the EPA primary DWS. Further, as noted 

3 in Section 2.2.5.2, the Deep Chicot Aquifer is separated from the Shallow Chicot Aquifer by a 

4 zone of predominantly clay material 100 to 150 ft (30 to 46 m) thick. The Deep Chicot Aquifer is 

5 the primary source of groundwater for the region, and tritium has not been detected in the Deep 

6 Chicot Aquifer (MACTEC 2009).

7 As a result of STPNOC’s participation in the Nuclear Energy Institute’s (NEI) Groundwater 

8 Protection Initiative (NEI 2007), data exist on tritium levels in groundwater, and a report was 

9 issued that compiled all information about groundwater and releases to groundwater in the STP, 

10 Units 1 and 2, protected area (MACTEC 2009). A peak tritium concentration around 

11 15,000 pCi/L was observed in the Upper Shallow Chicot Aquifer beneath the protected area in 

12 2006. Sampling at the location of that peak concentration has shown a continuous decline in 

13 tritium concentration with a concentration of 1,500 pCi/L observed in 2010. All measured tritium 

14 levels in groundwater within the protected area are below the EPA primary DWS 

15 (i.e., 20,000 pCi/L) (see Section 2.2.5.2).

16 Three possible sources of tritium in groundwater within the protected area have been identified

17 as seepage from the MCR, leaks of the TDS pipeline system, and discharge to the ground from 

18 the turbine steam trap drains or steam condensate lines. Tritium levels in groundwater 

19 originating in the MCR are bounded, as described above, and will be less than the EPA primary 

20 DWS. STPNOC has noted that the TDS pipeline system and the steam condensate line 

21 releases could have a maximum tritium concentration of less than 90,000 pCi/L 

22 (STPNOC 2011c). Releases to groundwater in the vicinity of the Units 1 and 2 reactors move 

23 downward from the Upper into the Lower Shallow Chicot Aquifer and then laterally to the east 

24 and southeast in the Lower Shallow Chicot Aquifer to the STP site boundary (NRC 2011b). As 

25 described in Section 2.2.5.2, the groundwater travel time from the protected area to the STP site 

26 boundary east of the protected area is approximately 100 years. This represents over 

27 8 half-lives of tritium decay; therefore, releases at the maximum level would decay to 

28 concentrations below the EPA primary DWS before leaving the STP site. The NRC staff has 

29 evaluated the releases inside the protected area, as well as relevant groundwater monitoring 

30 data. The staff concludes that no release is occurring from an unidentified pathway (based on 

31 accounting of releases from available records), and there is no substantial adverse impact on 

32 drinking water (the staff evaluates human health issues in Section 4.8). 

33 In addition to the foregoing, the following staff findings are relevant to the issue of groundwater 

34 quality impacts:

35 • Groundwater in the Shallow Chicot Aquifer will remain slightly saline and 

36 suitable to its current use for watering livestock. 

37 • Tritium levels in the Shallow Chicot Aquifer resulting from seepage from the 

38 MCR will not exceed the EPA primary DWS. 

39 • Tritium has not been detected in the Deep Chicot Aquifer, which is the 

40 primary groundwater source in the region. 

41 • Tritium levels in the Shallow Chicot Aquifer resulting from leaks and 

42 discharges inside the STP protected area are currently below the EPA DWS, 

43 and long-term tritium levels leaving the STP site from such releases would be 

44 below the EPA DWS.

45 In conclusion, based on this information—including the staff’s review of seepage from the MCR 

46 and the review of releases of liquids containing tritium within the protected area of STP, Units 1 
Environmental Impacts of Operation

4-11

1 and 2—the NRC staff concludes that groundwater contaminant plumes have not altered current 

2 groundwater use in the region downgradient of the STP site. The staff further concludes that 

3 groundwater-quality impacts would remain SMALL during the license renewal term.

4.5

5 Sections 2.1.6 and 2.2.5 describe the STP cooling system and aquatic environment. 

6 Section 2.2.7.1 describes the protected aquatic resources that could occur in the vicinity of STP 

7 and associated transmission lines. Category 1 and Category 2 issues related to aquatic 

8 resources applicable to STP are discussed below and listed in Table 4–7. 

4 Aquatic Resources

9 Table 4–7. Aquatic Resource Issues

Issues GEIS Section Category

For all plants

Accumulation of contaminants in sediments or biota 4.2.1.2.4 1

Entrainment of phytoplankton & zooplankton 4.2.2.1.1 1

Cold shock 4.2.2.1.5 1

Thermal plume barrier to migrating fish 4.2.2.1.6 1

Distribution of aquatic organisms 4.2.2.1.6 1

Premature emergence of aquatic insects 4.2.2.1.7 1

Gas supersaturation (gas bubble disease) 4.2.2.1.8 1

Low dissolved oxygen in the discharge 4.2.2.1.9 1

Losses from predation, parasitism, & disease among organisms 

exposed to sublethal stresses 4.2.2.1.10 1 

Stimulation of nuisance organisms 4.2.2.1.11 1

For Plants with Cooling Pond Heat-Dissipation Systems

Entrainment of fish & shellfish in early life stages 4.1.2 2

Impingement of fish & shellfish 4.1.3 2

Heat shock 4.1.4 2

10 4.5.1 Generic Aquatic Ecology Issues

11 The NRC staff did not identify any new and significant information related to the Category 1 

12 issues listed above during the review of STPNOC’s ER, the site audit, or the scoping process

13 that would change the conclusions presented in the GEIS (the NRC staff also reviewed other 

14 sources of information, such as applicable permits and data reports, as listed in the reference 

15 section of this SEIS chapter). Therefore, there is no impact related to these issues beyond 

16 those discussed in the GEIS. For these issues, the GEIS concluded that the impacts are 

17 SMALL. Additional site-specific mitigation measures are unlikely to be sufficiently beneficial to 

18 warrant implementation.
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1 4.5.2 Entrainment and Impingement

2 Entrainment and impingement of aquatic organisms are site-specific (Category 2) issues for 

3 assessing the impacts of license renewal at plants with cooling pond heat-dissipation systems. 

4 Entrainment is the taking in of organisms with a plant’s cooling water intake. The organisms 

5 involved are generally of small size, dependent on the screen mesh size, and include phyto6 and zooplankton, fish eggs and larvae, shellfish larvae, and many other forms of aquatic life. 

7 Impingement is the entrapment of organisms against the cooling water intake screens.

8 A particular species can be subject to both impingement and entrainment if some individuals are 

9 impinged on screens while others pass through and are entrained (EPA 1977). Section 316(b) 

10 of the Clean Water Act (CWA) (33 United States Code (U.S.C.) §1326(b)) requires that “[a]ny 

11 standard established pursuant to Section 1311 of this title or Section 1316 of this title and 

12 applicable to a point source shall require that the location, design, construction, and capacity of 

13 cooling water intake structures reflect the best technology available for minimizing adverse 

14 environmental impact.” 

15 At STP, organisms maybe impinged or entrained at two locations. Organisms that inhabit the 

16 lower Colorado River may be impinged or entrained when water is drawn through the reservoir 

17 makeup pumping facility (RMPF) from the Colorado River into the MCR. Organisms that inhabit 

18 the MCR may be impinged or entrained when water is drawn through the cooling water intake 

19 structure (CWIS) from the MCR to the cooling water system.

20 The adverse environmental impacts of cooling water intakes occur through both impingement 

21 and entrainment. Heat, physical stress, or chemicals used to clean the cooling system may kill 

22 or injure the entrained organisms. Exhaustion, starvation, asphyxiation, descaling, and physical 

23 stresses may kill or injure impinged organisms. STPNOC survey data in the MCR indicate that 

24 entrained organisms from the lower Colorado River can survive the stresses of the intake 

25 system at the RMPF and colonize the MCR (ENSR 2008a, 2008b). However, entrainment and 

26 colonization of the MCR removes these organisms from the rest of the ecosystem in the region. 

27 Entrained organisms that pass through the CWIS into the plant’s cooling system are subject to 

28 mechanical, thermal, and toxic stresses. Therefore, survival is unlikely.

29 Because impingement and entrainment are fundamentally linked, the NRC staff determined that 

30 effects of each should be assessed using an integrated approach. The NRC staff employed a 

31 weights-of-evidence (WOE) approach to evaluate the effects of impingement and entrainment 

32 on the aquatic resources in the lower Colorado River and the MCR. NRC employed this 

33 approach because EPA recommends a WOE approach for ecological risk assessments 

34 (EPA 1998). WOE is a useful tool due to the complex nature of assessing risk (or impact), and 

35 NRC has employed this approach in other evaluations of the effects of nuclear power plant 

36 cooling systems on aquatic communities (NRC 2010, 2011i).

37 Menzie et al. (1996) defines WOE as “the process by which multiple measurement endpoints 

38 are related to an assessment endpoint to evaluate whether significant risk of harm is posed to 

39 the environment.” In this modified WOE approach, the NRC staff examined five lines of 

40 evidence to determine if operation of the STP cooling system has the potential to cause adverse 

41 impacts to fish and shellfish near STP. The first line of evidence is impingement and 

42 entrainment studies at the RMPF during the initial filling and subsequent intermittent withdraw of 

43 water from the Colorado River to the MCR (McAden 1984, 1985). The second line of evidence 

44 is impingement and entrainment studies at the CWIS from 2007 through 2008 during the 

45 withdraw of water from the MCR through the circulating water system for STP, Units 1 and 2 

46 (ENSR 2008a). The third line of evidence includes engineering designs and operational 
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1 procedures to limit impingement and entrainment. The fourth line of evidence includes reviews 

2 by other regulatory agencies, such as EPA and the Texas Commission on Environmental 

3 Quality (TCEQ). The fifth line of evidence includes survey data of fish and shellfish populations 

4 prior to and during operations within the Colorado River.

5 Line of Evidence Number 1: Impingement and Entrainment Studies on the Colorado River

6 The NRC staff evaluated the potential impacts from impingement and entrainment during water 

7 withdrawal from the Colorado River by examining impingement and entrainment studies 

8 from 1983 to 1984. McAden et al. (1984, 1985) conducted studies at the RMPF when STPNOC

9 initially filled the MCR with Colorado River water. NRC (1986) assessed the environmental 

10 impacts of impingement and entrainment for the initial operating license for STP, Units 1 and 2.

11 McAden et al. (1984, 1985) conducted studies to estimate entrainment impacts by collecting 

12 surface plankton samples in front of the RMPF. McAden used a hand-towed 0.5-m 

13 (20-in. mouth diameter) ichthyoplankton net with 0.5-mm (0.02-in.) square mesh and swept the 

14 hand tow parallel to the front wall of the pump structure. The most commonly collected species 

15 included the zoeae and juveniles of Harris mud crabs (Rhithropanopeus harrisii), river shrimp 

16 (Macrobrachium ohione), and white shrimp (Litopenaeus setiferus), as shown in Table 4–8. 

17 McAden collected the eggs and larvae of two fish species—bay anchovy (Anchoa mitchilli) and 

18 mosquito fish (Gambusia affinis). McAden also conducted plankton tows in the Colorado River 

19 near the RMPF. The most commonly collected species of fish eggs and larvae included bay 

20 anchovy, Gulf menhaden (Brevoortia patronus), and Atlantic croaker (Micropogonias undulatus). 

21 Section 2.2.5.1 provides addition details regarding fish egg and larvae sampling in the Colorado 

22 River.

23 Based on the entrainment study by McAden et al. (1984, 1985), NRC (1986) estimated that 

24 entrainment losses would be approximately 10 percent of the organisms passing the RMPF. 

25 This value represents the loss of organisms in the influence of the tidal flow in the river and 

26 does not represent the entire populations of those species in the lower Colorado River.

27 NRC (1986) determined that the systems along the Texas Gulf coasts and the area influenced 

28 by the RMPF are not unique. In addition, NRC (1986) determined that species commonly 

29 caught in near the RMPF by McAden are ubiquitous (widespread or common) and abundant 

30 along the Texas and Gulf coasts. The reproductive potential (fecundity) for these species is 

31 high; therefore, the larvae entrained are a small portion of the total larvae produced by adult 

32 females for most species (NRC 2011b). In addition, most makeup water withdrawal would 

33 occur during high river flow conditions, which is when the salinity and concentrations of 

34 estuarine and marine organisms would be lowest. Therefore, NRC (1986) concluded that 

35 entrainment losses for the species collected by McAden (1984, 1985) would not constitute a 

36 significant impact to their respective populations.

37 ENSR Corporation (2008a) indicates that many individuals of numerous species survived 

38 entrainment at the RMPF and inhabit the MCR. While these organisms survived entrainment, 

39 the entrainment, overall, has led to a loss of the organisms in the Colorado River, and these 

40 organisms no longer contribute to the riverine ecosystem.

41
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Table 4–8. Number (per 100 m3 1 ) of Macrozooplankton and Ichthyoplankton Collected in 

2 Plankton Samples in Front of the RMPF from 1984 and 1985

Common Name Scientific Name Aug-83(a) Sept-83(b) Sept-84(c) Total % of 

Total

bay anchovy Anchoa mitchilli 51.3 0 0 51.3 1

bivalves-juveniles Pelecypoda 10.3 28.3 0 38.6 1

blue crab-juvenile Callinectes sapidus 62.8 14.1 0 76.9 2

crabs-megalopa Callinectes spp. 115 0 0 115 3

glass shrimp Palaemonetes paludosus 0 14.9 0 14.9 <1

Harris mud crab Rhithropanopeus harrisii 184.9 1,461.4 695.9 2,342.2 60

mosquito fish Gambusia affinis 23.3 14.9 0 38.2 1

ghost shrimp Callianassa spp. 0 0 51.4 51.4 1 

river shrimp Macrobrachium ohione 609.3 29 0 638.3 16

white shrimp Litopenaeus setiferus 222.2 312.8 0 535 14

unidentified fish spp. 0 0 12.9 12.9 <1

Total 1,279.1 1,875.4 760.2 3,914.7

(a) Samples collected on August 9–10, 1983, at 1100, 1640, 2230, and 0450

(b) Samples collected on September 15–16, 1983, at 1100, 1705, 2250, and 0545

(c) Samples collected on September 6, 1984, at 0020, 0500, 1030, and 1615

Source: McAden 1984, 1985 

3 McAden et al. (1984, 1985) also conducted impingement studies by washing all organisms off 

4 two intake screen and filtering them through a dip net with a 0.25-in (6.4-mm) mesh. Each 

5 sample period was 30 minutes. McAden (1984, 1985) collected three samples within 24 hours 

6 during each week that pumping occurred. The most commonly impinged species included blue 

7 crab (61 percent), river shrimp (18 percent), and white shrimp (10 percent), as shown in Table 

8 4–9. Impinged fish included one crevalle jack (Caranx hippos), one green sunfish (Lepomis 

9 cyanellus), and one inland silverside (Menidia beryllina). Because the impingement study 

10 collected so few fish, NRC (1986) predicted the most likely fish to be impinged based on size 

11 (which is related to swim speed) and the density and abundance of the species near the RMPF. 

12 NRC (1986) predicted Gulf menhaden to be the most commonly impinged species (65 percent), 

13 followed by Atlantic croaker (16 percent), bay anchovy (10 percent), and striped mullet 

14 (8 percent). NRC (1986) concluded that impingement losses would have a minor effect on the 

15 biota of the Colorado River because the commonly impinged species are ubiquitous, abundant 

16 habitat for these species occurs along the Texas and Gulf coasts, and the design elements of 

17 the RMPF would reduce impingement losses.

18 STPNOC has not conducted impingement and entrainments studies on the Colorado River 

19 since its 1983 to 1984 study (STPNOC 2010b, 2010c). Since 1984, the U.S. Army Corps of 

20 Engineers (USACE) completed the mouth of the Colorado River project, increasing the flow 

21 between the Colorado River and Matagorda Bay (USACE 2005; Wilber and Bass 1998). As 

22 discussed below in the aquatic survey section (line of evidence number 5), the diversity of 

23 aquatic species and the presence of estuarine-marine species has increased since the 1970s. 
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1 However, ENSR (2008b) found that the majority of the species most likely to be impinged 

2 (e.g., Gulf menhaden, Atlantic croaker, and striped mullet) continue to be the most common 

3 species of fish collected around the RMPF and would likely continue to be the most common 

4 species impinged during the license renewal term.

5 Table 4–9. Invertebrates and Fish Impinged at the RMPF during 1983–1984 Studies

Common Name Scientific Name July-83(a) Aug-83(b) Sept-83(c) Sept-84(d) Total % of 

Total

blue crab Callinectes sapidus 69 44 4 6 123 61

crevalle jack Caranx hippos 1 0 0 0 1 <1

glass shrimp

Palaemonetes 

paludosus 14 1 0 0 15 7 

grass shrimp

Palaemonetes 

kadiakensis 1 1 0 0 2 1 

green sunfish Lepomis cyanellus 1 0 0 0 1 <1

inland silverside Menidia beryllina 1 0 0 0 1 <1

pink shrimp

Farfantepenaeus 

brasiliensis 0 0 0 1 1 <1

Palaemonidae 

shrimp Palaemonidae spp. 2 0 0 0 2 1 

river shrimp 

Macrobrachium 

ohione 28 4 1 4 37 18

white shrimp Litopenaeus setiferus 0 3 13 4 20 10

Total 117 53 18 15 203

(a) Samples collected on July 13–14, 1983, at 1329, 2100, and 0511; July 21–22, 1983, at 1315, 2110, 0505; and 

July 27–28, 1983, at 1400, 2230, and 0626.

(b) Samples collected on August 9–10, 1983, at 1300, 2100, and 0500.

(c) Samples collected on September 15–16, 1983, at 1414, 2205, and 0615.

(d) Samples collected on September 5–6, 1984, at 1910, 0300, and 1104.

Source: McAden 1984, 1985 

6 Line of Evidence Number 2: Impingement and Entrainment Studies on the Main Cooling 

7 Reservoir

8 STP conducted impingement and entrainment studies at the CWIS on the MCR in May 2007 

9 through April 2008 (ENSR 2008a). The objective of the study was “to characterize the aquatic 

10 species within the MCR, and to evaluate impingement and entrainment impacts to establish, to 

11 the extent possible, relationships between the presence of aquatic organisms and the current 

12 (STP, Units 1 and 2) intake design and operating parameters” (ENSR 2008a).

13 ENSR (2008a) collected entrainment samples over a 24-hour period, twice per month from May 

14 through September and once per month from October through April. ENSR collected 

15 entrainment samples by placing 0.363-mm (0.014-in.) plankton nets behind the trash bars at the 

16 CWIS. ENSR pumped water from a depth of approximately 12 ft (3.7 m) through a buffering 

17 chamber at flows up to 10,800 gallons per hour or 180 gpm. ENSR operated the pumps four 
Environmental Impacts of Operation

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times per day, for approximately 2 hours per event, for a volume of 100 m3 (3,500 ft3 1 ) of water 

2 per 24-hour period.

3 ENSR (2008a) collected 207,696 organisms representing nine different fish families and 

4 12 different classes of invertebrates (Table 4–10). The most commonly impinged taxa included 

5 Harris mud crab (68 percent) and unidentified decapod zoea (or free swimming larvae) 

6 (15 percent). Ichthyoplankton, or fish eggs and larvae, comprised less than 1 percent of all 

7 entrained organisms. ENSR reported the highest entrainment rates from April through June and 

8 the lowest from December through March. Entrainment of threadfin shad and mud crabs was 

9 highest in late spring and summer, and entrainment of silversides was highest in summer.

10 Table 4–10. Aquatic Species Collected during Entrainment 

11 Sampling in the MCR’s CWIS for Units 1 and 2, 2007–2008

Common Name Taxon Total Number % of Total

Finfish

anchovy Anchoa spp. 30 <1

clupeid Clupeidae 544 <1

fish egg 418 <1

goby Gobiidae 61 <1

perch-like fish Perciformes 6 <1

naked goby Gobiosoma bosc 5 <1

needlefish Belonidae 3 <1

silversides Atherinidae 201 <1

wrasse Labridae 3 <1

Invertebrates

amphipod Amphipoda 145 <1

bivalve Mollusca 1 <1

brachyuran decapod (zoea) Brachyura 353 <1

copepod Copepoda 6,588 3

decapod (mud crabs) Panopeidae 10,798 5

decapod (zoea) Decapoda 31,919 15

fish lice Copepoda 399 <1

harpacticoid copepod Copepoda 12,212 6

Harris mud crab Rhithropanopeus harrisii 140,192 68

insect Insecta 24 <1

midge Diptera 110 <1

mite or ticks Acari 12 <1

mysid shrimp Mysida 2,660 1

polychaete Annelida 4 <1

seed shrimp Ostracoda 78 <1
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Common Name Taxon Total Number % of Total

shrimp Caridea 1 <1

tongue biters Isopoda 16 <1

water flea Cladocera 800 <1

unidentified 113 <1

Total 207,696

Source: ENSR 2008a

1 ENSR (2008a) collected impingement samples over a 24-hour period, twice per month from 

2 May through September and once per month from October through April. ENSR collected 

3 samples by placing a metal-framed net fitted with a 0.25-in. (6.4-mm) nylon mesh net within the 

4 sluiceway that connects the CWIS screen wash system and the debris basket.

5 ENSR (2008a) collected a total of 3,982 organisms representing 25 finfish and 7 invertebrate 

6 species (Table 4–11). The most commonly impinged species includes threadfin shad 

7 (Dorosoma petenense) (42 percent), blue crab (24 percent), mud crab (24 percent), Atlantic 

8 croaker (5 percent), and white shrimp (3 percent). Blue crab impingement was highest during 

9 the months of May, June, and July, and threadfin shad impingement was highest during the 

10 months of January and March. ENSR did not report any other temporal trends for individual 

11 species or all species combined.

12 Table 4–11. Aquatic Species Collected during Impingement 

13 Sampling in the MCR’s CWIS for Units 1 and 2, 2007–2008

Common Name Scientific Name Total Number % of Total

Finfish

American eel Anguilla rostrata 1 <1

Atlantic croaker Micropogonias undulatus 182 5

bay anchovy Anchoa mitchilli 3 <1

bay whiff Citharichthys spilopterus 2 <1

black drum Pogonias cromis 2 <1

blue catfish Ictalurus furcatus 6 <1

bluegill Lepomis macrochirus 9 <1

channel catfish Ictalurus punctatus 4 <1

common carp Cyprinus carpio carpio 2 <1

freshwater drum Aplodinotus grunniens 5 <1

freshwater goby Ctenogobius shufeldti 2 <1

gizzard shad Dorosoma cepedianum 2 <1

goby Gobiidae spp. 8 <1

Gulf menhaden Brevoortia patronus 2 <1
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Common Name Scientific Name Total Number % of Total

inland silverside Menidia beryllina 5 <1

ladyfish Elops saurus 1 <1

naked goby Gobiosoma bosc 13 <1

needlefish Strongylura exilis 2 <1

rough silverside Membras martinica 2 <1

sand seatrout Cynoscion arenarius 3 <1

sharptail goby Oligolepis acutipennis 2 <1

sheepshead Archosargus probatocephalus 1 <1

speckled worm eel Myrophis punctatus 1 <1

spot croaker Leiostomus xanthurus 1 <1

threadfin shad Dorosoma petenense 1,668 42

Invertebrates

blue crab Callinectes sapidus 944 24

brown shrimp Farfantepenaeus aztecus 10 <1

grass shrimp Paleemonetes pugio 33 <1

lesser blue crab Callinectes similis 3 <1

Harris mud crab Rhithropanopeus harrisii 953 24

river shrimp Macrobrachium ohione 3 <1

white shrimp Litopenaeus setiferus 106 3

Other

flat-headed snake Tantilla gracilis 1 <1

Total 3,982

Source: ENSR 2008a

1 Line of Evidence Number 3: Engineered Design and Operational Conditions

2 EPA recently published a proposed rule that describes multiple approaches to reduce 

3 impingement and entrainment mortality at existing cooling water intake structures. These 

4 approaches include flow reduction, or reducing the total amount of water withdrawn; intake 

5 velocity; technologies to exclude organisms and to collect and return organisms to the water

6 body; and intake location and timing of withdrawals (76 FR 22174). The RMPF on the Colorado 

7 River and the CWIS on the MCR incorporate several of these approaches.

8 Flow Reduction. Reducing the intake flow reduces the amount of water withdrawn from water

9 bodies to be cycled through the cooling system, which likely reduces the amount of aquatic 

10 organisms that would be drawn through the intake structure and subject to impingement and 

11 entrainment. STP uses a cooling pond-based heat-dissipation system that withdraws and 

12 discharges cooling water to the MCR. The MCR is similar to a closed-cycle cooling system 
Environmental Impacts of Operation

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1 since the water in the reservoir continues to circulate from the MCR, into the plant, and back 

2 again. STP intermittently draws water from the Colorado River to compensate for water loss 

3 from evaporation and seepage from the MCR. Depending on the quality of the makeup water, 

4 closed-cycle recirculating cooling water systems can reduce consumptive water use by 

5 96 to 98 percent of the amount that the facility would use if it employed a once-through cooling 

6 system (69 FR 41576). 

7 Reduced Intake Velocity. Water velocity associated with the intake structure greatly influences 

8 the rate of impingement and entrainment. The higher the approach or through-screen velocity

9 or both, the greater the number of organisms impinged or entrained. At an approach velocity of 

10 0.5 ft/s (0.15 m/s) or less, most fish can swim away and escape from the intake current 

11 (66 FR 65274). The maximum design approach velocity in front of the traveling screens at the 

12 RMPF is approximately 0.5 ft/s, based on a maximum pumping rate of approximately 

538,000 gpm (2,040 m3 13 /min) (STPNOC 2008a, 2008c, 2010c).

Technologies to exclude organisms and to collect and return organisms to the water body

24 During high-flow conditions, the accumulation of debris on the traveling screens is too high to 

25 open the fish bypass system, and screenwash discharge is directed to the sluice trench catch 

26 baskets rather than back to the river. Generally, the fish bypass system is closed when river 

flows are greater than 4,000 cfs (100 m3 27 /s), and the system is occasionally closed when flows 

are greater than 2,000 cfs (60 m3 28 /s), which has occurred from 2001 to 2006, 7 percent of the 

29 time (STPNOC 2008a, 2008c, 2010c). Operators at the RMPF are required to monitor for 

30 increased impingement rates on the traveling screens, and operators evaluate relevant 

31 factors—such as river flow, salinity, and observations of impingement—to determine whether 

32 pumping should continue (STPNOC 2008a, 2008c, 2010c).

14 . The 

15 RMPF has several technologies that help exclude organisms from becoming impinged or 

16 entrained. The RMPF has coarse trash racks with 4-in. (10-cm) spacing between bars, which 

17 would impede larger organisms from entering the intake system (STPNOC 2010c). After 

18 passing through trash racks, water flows through traveling screens with a 3/8 in. (9.5 mm) mesh 

19 (STPNOC 2010c). The space between the trash racks and the traveling screens allow fish to 

20 swim downstream and exit the intake structure (STPNOC 2010c). Fish collected or washed 

21 from the traveling screens can also return to the river via a sluice and fish bypass pipe. The 

22 discharge point of the fish bypass system is at the downstream end of the intake structure, 

23 approximately 2 ft (0.6 m) below normal water elevation (STPNOC 2010c).

Intake Location and Time of Withdrawals

42 STPNOC designed the RMPF to position the traveling intake screens parallel to the flow in the 

43 river, or “flush” to the river bank with no projecting structures that create eddies and 

44 countercurrents that would cause entrapment (NRC 1986; STPNOC 2010c). Most organisms 

45 likely to be entrained or entrapped would occur in higher densities in the main river channel. 

46 They are less likely to be removed from the river by an intake facility sited on the shoreline 

47 (NRC 2011b). Entrapment of aquatic organisms in a restricted area (e.g., in the sedimentation 

33 . Location of the intake system is another design factor 

34 that can affect impingement and entrainment because water drawn from areas with lower 

35 biological productively is less likely to include organisms that could be impinged or entrained. 

36 The RMPF is located on the Colorado River, which is designated as a tidal stream and includes 

37 essential fish habitat (EFH) for Federally managed fish and shellfish species (GMFMC 2004). 

38 Locating intake systems in such areas with sensitive biological productivity can negatively affect 

39 aquatic life (69 FR 41576). However, the area of the river where the RMPF is situated has 

40 fewer organisms and less species richness than the downstream segment of the river, closer to 

41 the GIWW (ENSR 2008b).
Environmental Impacts of Operation

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1 basin between the RMPF intake screens and the pumps and in the MCR) can lead to 

2 congregation of the organisms, and, if environmental conditions change, the organisms may be 

3 harmed. Under such conditions, entrapment can increase impingement of aquatic organisms.

4 Operational procedures for the RMPF also minimize impingement and entrainment because 

5 STPNOC intermittently draws water from the Colorado River for Units 1 and 2, and pumping 

6 occurs during periods of lower biological productivity. For example, STPNOC (2010b) noted 

7 that most withdrawals would occur during periods of high river flow. Pumping at high-flow 

8 conditions minimizes impacts to aquatic organisms in the water column because the organisms 

9 are likely to remain in the river flow and unlikely to be caught in the influence of the water being 

10 pumped into the RMPF located on the shoreline (STPNOC 2008a, 2008c, 2010b, 2010c). In 

11 addition, periods of high river flow (fall through spring) generally correlate with lower biological 

12 productivity when less young and estuarine-marine organisms are present (NRC 1986; 

13 STPNOC 2010b). During the 2007 to 2008 aquatic ecology studies in the Colorado River, fish 

14 density (as expressed in the catch per unit effort) was lowest during high river flow conditions 

15 and when salinity was lowest (ENSR 2008b; STPNOC 2008a, 2008c). Salinity can be an 

16 indicator of an influx of estuarine species moving up the river from the GIWW.

17 Line of Evidence 4: Other Regulatory Reviews

18 Section 316(b) of the CWA requires that the location, design, construction, and capacity of 

19 cooling water intake structures reflect the best technology available for minimizing adverse 

20 environmental impacts. As part of STPNOC’s original National Pollutant Discharge Elimination 

21 System (NPDES) permit application, in a letter dated June 28, 1982, STPNOC provided EPA 

22 with detailed information on the design and operation of the RMPF (STPNOC 2010b). Based 

23 on this information, EPA concluded that “the intake structure is approved by Best Available 

24 Technology in accordance with Section 316(b) of the CWA” (EPA 1985).

25 TCEQ has administered STPNOC’s Texas Pollutant Discharge Elimination System (TPDES) 

26 permit since 1998, when EPA delegated authority to the State of Texas to administer the State’s 

27 permit program. STPNOC submitted a TPDES permit renewal application by letter dated 

28 May 24, 2007. Included in this application was a description of how the cooling water system is 

29 a closed-cycle recirculating system and, as such, meets the best available technology standard 

30 for minimizing adverse environmental impacts (STPNOC 2010b). For example, STPNOC noted 

31 that the MCR recycles water for heat-dissipation and is not a water of the U.S. or a water of the 

32 State. TCEQ Water Quality Division concurred that the STP cooling system operates as a 

33 closed-cycle recirculating system and that the MCR is not a water of the State (TCEQ 2007). 

34 Neither EPA nor the State of Texas has requested additional studies from STPNOC in regards 

35 to a 316(b) determination (STPNOC 2010b).

36 Line of Evidence Number 5: STP Survey Data on the Colorado River

37 Impingement and entrainment from current operations of the RMPF have removed individuals 

38 from the Colorado River ecosystem. One method to determine the impacts to aquatic resources 

39 from operation of the RMPF is to compare the species abundance and diversity prior to and 

40 during operations. ENSR (2008b) compared the aquatic community in the Colorado River using 

41 the results of field studies from 1974 (HPLC 1974), 1983 and 1984 (McAden 1984, 1985), and 

42 2007 through 2008 (ENSR 2008b). The 1970s studies were conducted in support of the 

43 construction permit for STP, Units 1 and 2. McAden (1984, 1985) conducted studies in support 

44 of the operating license for STP, Units 1 and 2. ENSR (2008b) sampled portions of the 

45 Colorado River in support of the combined license (COL) for proposed Units 3 and 4. 

46 Section 2.2.5.1 provides additional details of these studies. Because the sampling locations 

47 and gear types varied with each study, it can be difficult to determine whether changes over 
Environmental Impacts of Operation

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1 time are due to plant operations, other anthropogenic or environmental changes, or study 

2 methods.

3 ENSR (2008b) compared species richness from trawl surveys conducted in 1974, 1983, 

4 and 2007 through 2008. Species richness was generally higher in 2007 through 2008 

5 compared to earlier surveys (ENSR 2008b), as shown in Figure 4–1. For example, species 

6 richness in Segment C, which is closest to the RMPF, increased from 12 in the 1974 study to 

7 24 in 2007 through 2008 study. Because STPNOC gathered data for only 2 or 3 years in each 

8 segment of the river, it is unclear whether the change in diversity is part of a long-term temporal 

9 change or whether the physical conditions in the river (e.g., lower salinity in the 1970s), or 

10 another variable, contributed to the different levels of diversity in 1974 compared to 2007 and 

11 2008.

12 Figure 4–1. Species Richness of Aquatic Species Captured in Trawl Surveys

13 from 1974, 1983, and 2007 through 2008

14 ENSR (2008b) calculated the Jaccard coefficients of community similarity to determine 

15 similarities between the samples collected over time in similar reaches of the lower Colorado

16 River based on the presence or absence of taxa. For this measure, as the coefficient 

17 approaches 1.0, the more taxa in the two samples are the same. Conversely, as the coefficient 

18 approaches 0, the samples have fewer taxa in common. For samples collected in the area 

19 closest to the RMPF (Segment C), the Jaccard coefficient was 0.36, when comparing 

20 2007 to 2008 samples to 1974 samples, and 0.37, when comparing 2007 to 2008 samples to 

21 1983 to 1984 samples. Similar comparisons with seine data resulted in coefficient values 

22 of 0.31 (for 1974) and 0.33 (for 1983 to 1984). ENSR (2008b) also compared trawl data 

23 throughout all river segments for 1974 and 2007 to 2008 data, which resulted in a Jaccard 

24 coefficient of 0.44. These results suggest low to moderate similarity of the species collected 

25 in 1974 and 1983 through 1984 compared to 2007 through 2008.

0 

5 

10

15

20

25

30

35

40

Segment A Segment B Segment C

Species Richness

River Segment

1974

1983

2007-2008
Environmental Impacts of Operation

4-22

1 The results of ENSR (2008b) suggest that the current aquatic community is different and may 

2 be slightly more diverse than the aquatic community inhabiting the Colorado River during the 

3 start of operations for STP, Units 1 and 2. ENSR (2008b) observed changes in diversity near 

4 the RMPF as well as further downstream, which would be less likely to be impacted by STP 

5 operations. The increase in flow between the Colorado River and Matagorda Bay has likely 

6 contributed to the changes in community structure and the increase in species diversity of 

7 aquatic species by providing passage for saltwater and estuarine species from the lower 

8 Colorado River to Matagorda Bay (NRC 2011b). Based on the information from the latest 

9 survey data and what is known about the design of the RMPF, the operation of the RMPF does 

10 not appear to have noticeably altered populations of the species currently found in the river.

11 Conclusion

12 The NRC staff examined five lines of evidence to determine if impingement and entrainment 

13 have the potential to cause adverse impacts to fish and shellfish near STP. The first line of 

14 evidence includes impingement and entrainment studies at the RMPF during the initial filling 

15 and subsequent intermittent withdraw of water from the Colorado River to the MCR 

16 (McAden 1984, 1985). The second line of evidence includes impingement and entrainment 

17 studies at the CWIS from 2007 through 2008 during the withdraw of water from the MCR 

18 through the circulating water system (ENSR 2008a). The third line of evidence includes 

19 engineering designs and operational procedures to limit impingement and entrainment. The 

20 fourth line of evidence includes reviews by other regulatory agencies, such as EPA and the 

21 TCEQ. The fifth line of evidence includes survey data of fish and shellfish populations prior to 

22 and during operations within the Colorado River.

23 STPNOC conducted limited studies of impingement, entrainment, and aquatic monitoring at the 

24 RMPF in the lower Colorado River. However, in considering the best available information for 

25 the staff’s analysis, the results and conclusions of earlier impingement and entrainment studies 

26 and evaluations, such as McAden (1983, 1984) and NRC (1986), are likely still applicable 

27 because the most commonly impinged species are still common in the area near the RMPF 

28 (ENSR 2008b). Additionally, the design features of the RMPF that minimize losses of 

29 organisms would not change during the period of extended operations. In addition, EPA (1985) 

30 has concluded that the design of the RMPF reflects best available technology for minimizing 

31 adverse environmental impacts. Based on the information from current and historical surveys, 

32 impingement and entrainment studies, and the design of the RMPF and the cooling system, 

33 operation of the STP cooling system does not appear to have noticeably altered populations of 

34 the species currently found in the river. Therefore, the NRC staff concludes that the impact from 

35 entrainment and impingement by the STP cooling water system on aquatic resources is SMALL.

36 4.5.3 Thermal Shock

37 For plants with cooling pond heat-dissipation systems, NRC’s GElS (1996) lists the effects of 

38 heat shock as an issue requiring plant-specific, Category 2, evaluation before license renewal. 

39 The NRC (1996) made impacts on fish and shellfish resources resulting from heat shock a 

40 site-specific issue because of continuing concerns about thermal discharge effects and the 

41 possible need to modify thermal discharges in the future in response to changing environmental 

42 conditions.

43 Information considered in this analysis includes STPNOC’s TDPES permit, modeling of the 

44 thermal plume, the type of cooling system (cooling pond heat-dissipation system in this case), 

45 and other information. To perform this evaluation, the NRC staff (a) reviewed the STPNOC’s 
Environmental Impacts of Operation

4-23

1 ER (STPNOC 2010b), STPNOC’s TPDES permit (TCEQ 2005), and thermal plume modeling 

2 results (NRC 2011b) and (b) performed an audit at the STP site.

3 As described in Section 2.2.3, STP discharge to the Colorado River is permitted under its 

4 TPDES permit (TCEQ 2005). The permit allows the average daily discharge to be 144 million

5 gallons per day (gpd). The TPDES permit also limits the daily average temperature to 95 °F 

6 and the daily maximum temperature to 97 °F. TCEQ based these limits on site-specific (or 

7 segment-specific) TCEQ water quality rise standards for Segment 1401, Colorado River Tidal, 

8 at Title 30, Chapter 307.10, Appendix A, pursuant to the Texas Administrative Code. The 

9 TPDES permit also prohibits discharges that would exceed 12.5 percent of the flow of the 

10 Colorado River at the discharge point or when the flow in the Colorado River adjacent to STP is 

11 less than 800 cfs. An EPA online database indicated that STP has had no CWA formal 

12 enforcement actions or violations related to discharge temperature in the last 5 years 

13 (STPNOC 2011c). Neither EPA nor TCEQ has required STPNOC to seek a 316(a) variance or 

14 conduct studies in support of a 316(a) variance (STPNOC 2010b).

15 STPNOC operating procedures limit the blowdown flow rates and the number of discharge ports 

16 to be used during discharge events (STPNOC 2010b). For example, operators may open two to 

17 seven blowdown valves, depending on the blowdown rate (STPNOC 2010b). STPNOC 

18 procedures prescribe a range of allowable blowdown rates, from 80 to 308 cfs, depending on 

19 the Colorado River flow (STPNOC 2010b).

20 NRC (2011b) modeled the potential thermal plume from discharges to the Colorado River based 

21 on the continued operations of STP, Units 1 and 2, as well as the operation of proposed Units 3 

22 and 4. While this SEIS solely pertains to continued operation of STP, Units 1 and 2, the results 

23 of NRC’s (2011b) modeling study are presented for the following reasons:

24 • During operations of Units 3 and 4, discharge from all four units would mix in 

25 the MCR, and STPNOC would operate a single outfall to discharge water 

26 from the MCR (STPNOC 2010c). 

27 • The same TPDES permit would cover Units 1 through 4 (STPNOC 2010c). 

28 • Modeling the thermal plume based on four-unit operation bounds the 

29 potential impacts from continued operations of STP, Units 1 and 2.

30 NRC (2011b) determined that the maximum thermal plume dimensions would occur during the 

31 greatest difference in temperatures between the MCR water and the water in the river (20.4 °F), 

32 highest MCR discharge rate through seven ports (44 cfs per port, for a total of 308 cfs discharge 

33 rate), and the minimal flow in the Colorado River where the discharge would be equal to 

34 12.5 percent of the total flow in the river (2,464 cfs). NRC (2011b) modeled these conditions 

35 using a CORMIX (U.S. EPA computer code) mixing-zone model to determine the likely water 

36 temperature increases, the likely duration and frequency of discharge, and the dimensions of 

37 the thermal plume. The model indicated that a portion of the Colorado River would remain at 

38 ambient water temperature, allowing mobile aquatic organisms to avoid the thermal plume by 

39 passing the plume on the bottom of the river and throughout much of the water column. For 

40 example, during the maximum expected thermal plume dimensions, the thermal plume that is 

41 5 °F (2.8 °C) above ambient conditions reaches the bottom of the river from the last port of the 

42 discharge pipe to 120 ft (37 m) downstream, and the plume extends approximately 25 percent

43 across the width of the river. In that part of the river, the benthic invertebrate species 

44 (e.g., grass (Palaemonetes pugio), white, and brown shrimp) would be able to move along the 

45 bottom of the river on the far side of the discharge structure without passing through the 

46 elevated temperature plume. Approximately 120 ft (37 m) downstream of the last port of the 
Environmental Impacts of Operation

4-24

1 discharge pipe, the positive buoyancy of the warmer water causes the plume to rise to the 

2 surface of the river. NRC (2011b) predicted the surface of the river to have an elevated 

3 temperature across the entire width of the river from approximately 1,060 ft (323 m) from the 

4 last port of the discharge pipe to about 4,400 ft (1,341 m) downstream from the ports. As the 

5 plume rises to the surface and extends from bank to bank, however, a portion of the water 

6 column would remain at ambient river temperatures and would allow mobile organisms—such 

7 as foraging fish (e.g., Gulf menhaden, black drum (Pogonias cromis), spotted seatrout 

8 (Cynoscion nebulosus), striped mullet)—to move up and downstream.

9 Less mobile organisms would not be able to swim away to avoid the thermal plume, such as 

10 eggs, larvae, and mollusks. The most common juvenile and adult species collected in 

11 Segment B, where the plume could reach across the river at the surface, include Gulf 

12 menhaden, grass shrimp, black drum, white shrimp, and striped mullet (ENSR 2008b). The 

13 overall impact to these species from the effects of the thermal plume would be unlikely to

14 noticeably alter these populations because these organisms have a high fecundity, and the 

15 number of organisms lost would be insignificant compared to their population in the lower 

16 Colorado River.

17 NRC’s (2011b) simulation models the discharge plume based on four-unit operations, which 

18 would likely be larger and occur more often than the discharge from continued operations of 

19 STP, Units 1 and 2. For example, STPNOC has discharged to the Colorado River once during 

20 the operation of STP, Units 1 and 2, in 1997, as part of a system test (STPNOC 2010b). For 

21 four-unit operations, STPNOC estimated that water from the MCR would be discharged to the 

22 Colorado River as frequently as once every 11 days and could be continuous for as much as 

23 75 days (NRC 2011b). NRC (2011b) determined that STPNOC’s discharge operating policy 

24 would rarely result in discharges from the MCR that would create a thermal plume during times 

25 when river water quality is poor.

26 The STP cooling system also limits thermal impacts to the MCR and the Colorado River. STP 

27 uses a cooling pond-based heat-dissipation system that withdraws and discharges cooling 

28 water to the MCR. The MCR is similar to a closed-cycle cooling system since the water in the 

29 reservoir continues to circulate from the MCR, into the plant, and back again. STP discharges 

30 to the Colorado River to maintain water chemistry and quality within the MCR. Because the 

31 water within the MCR is reused, discharges are generally less frequent than other types of 

32 cooling systems, such as once-through cooling systems.

33 After reviewing the status of STPNOC’s TPDES permit, modeling of the thermal plume, and the 

34 type of cooling system at STP, the NRC staff concludes that the level of thermal impacts to the 

35 aquatic community due to renewing the STP operating license is SMALL. The thermal plume is 

36 unlikely to noticeably impact aquatic resources near STP for the following reasons:

37 • STPNOC’s TPDES permits limit the amount and timing of discharges. 

38 • Modeling studies indicate that mobile aquatic species could avoid the thermal 

39 plume by swimming at a lower depth or different side of the river. 

40 • Species or life-stages that are less mobile organisms would not be able to 

41 swim away to avoid the thermal plume, such as eggs, larvae, and mollusks. 

42 However, most species observed in this area generally have high fecundity, 

43 and the number of organisms lost would be insignificant compared to their 

44 population in the lower Colorado River. 
Environmental Impacts of Operation

4-25

1 • Cooling water is not regularly discharged into the Colorado River since STP 

2 uses a cooling pond-based heat-dissipation system that reuses water from 

3 the MCR.

4 4.5.4 Mitigation

5 The design of the RMPF and operating procedures mitigate potential impingement, entrainment, 

6 and thermal shock to aquatic organisms in the lower Colorado River as follows:

7 • Flow Reduction—STPNOC reduces the flow rate, or amount of water 

8 withdrawn from the Colorado River, by reusing water in the MCR.

9 • Reduced Intake Velocity—At an approach velocity of 0.5 ft/s or less, most fish 

10 can swim away and escape from the intake current (66 FR 65274). The 

11 maximum design approach velocity in front of the traveling screens at the 

12 RMPF is approximately 0.5 ft/s, based on a maximum pumping rate of 

13 approximately 538,000 gpm (STPNOC 2008, 2010c).

14 • Technologies to Exclude Organisms and to Collect and Return Organisms to 

15 the Water Body—The RMPF has coarse trash racks, traveling screens, and a 

16 fish bypass system (STPNOC 2010c).

17 • Intake Location—The RMPF is situated in a portion of the lower Colorado

18 River that has lower density of many fish and invertebrates and overall lower 

19 species richness than further downstream, closer to the GIWW 

20 (ENSR 2008b).

21 • Time of Withdraws—Operational procedures for the RMPF also minimize 

22 impingement and entrainment because STPNOC intermittently draws water 

23 from the Colorado River for Units 1 and 2, and pumping occurs during 

24 periods of lower biological productivity (e.g., periods of high river flow and 

25 lower salinity).

26 Additional details regarding these mitigation measures are described above, in Section 4.5.1.

4.6

28 The issues related to terrestrial resources applicable to STP are listed in Table 4–12. There is 

29 no Category 2 issue related to terrestrial resources. The NRC staff did not identify any new and 

30 significant information during the review of STPNOC’s ER, the staff’s site audit, the scoping 

31 process, or the evaluation of other available information (e.g., applicable permits and data 

32 reports as listed in the reference section of this SEIS chapter). Therefore, there is no impact 

33 related to these issues beyond those discussed in the GEIS. For these issues and consistent 

34 with the GEIS, the NRC staff concludes that the impacts to terrestrial resources are SMALL, and 

35 additional site-specific mitigation measures are unlikely to be sufficiently beneficial to warrant 

36 implementation. 

27 Terrestrial Resources

37
Environmental Impacts of Operation

4-26

1 Table 4–12. Terrestrial Resources Issues Identified in the GEIS

Issue GEIS Section Category

Cooling tower impacts on crops & ornamental vegetation 4.3.4 1

Cooling town impacts on native plants 4.3.5.1 1

Bird collisions with cooling towers 4.3.5.2 1

Powerline right-of-way management (cutting herbicide application) 4.5.6.1 1

Bird collisions with powerlines 4.5.6.1 1 

Impacts of electromagnetic fields on flora & fauna (plants, agricultural 

crops, honeybees, wildlife, livestock) 4.5.6.3 1 

Floodplains & wetland on powerline right-of-way 4.5.7 1

Source: Table B–1 in Appendix B, Subpart A, to 10 CFR Part 51

4.7

3 Section 2.2.7 of this SEIS describes protected species and habitats in the vicinity of the STP 

4 site. Table 4–13 lists the one Category 2 issue related to protected species and habitats that is 

5 applicable to STP.

2 Protected Species and Habitats

6 Table 4–13. Protected Species Issues Identified in the GEIS

Issue GEIS Section Category

Threatened or endangered species 4.1 2

Source: Table B–1 in Appendix B, Subpart A, to 10 CFR Part 51

7 This site-specific, or Category 2 issue, requires consultation with the appropriate agencies to 

8 determine whether threatened or endangered species are present and whether they would be 

9 adversely affected by continued operation of STP during the license renewal term. In the case 

10 of STP, the U.S. Fish and Wildlife Service (FWS) is responsible for terrestrial and freshwater 

11 species listed under the Endangered Species Act (ESA), the Bald and Golden Eagles Act, and 

12 the Migratory Bird Treaty Act (MBTA). The National Marine Fisheries Service (NMFS) is 

13 responsible for marine and anadromous species listed under the ESA and the 

14 Magnuson–Stevens Fishery Conservation and Management Act (MSA) and those species that 

15 have been designated as NMFS Species of Concern. The Texas Parks and Wildlife Division is 

16 responsible for species protected by the State of Texas Statutes. Descriptions of protected 

17 species and habitats appear in Section 2.2.8. 

18 Listed Species Protected Under the Endangered Species Act. The NRC staff corresponded 

19 with both the FWS and NMFS to determine impacts to Federally listed species and to decide 

20 whether to initiate Section 7 consultation as a result of the proposed STP license renewal. The 

21 NRC developed a list of Federally listed species within the vicinity of STP and requested 

22 concurrence on this list in a February 16, 2011, letter (NRC 2011f). The FWS responded to this 

23 request on June 2, 2011, with an updated list and recommendations concerning specific species

24 (FWS 2011). Specific species for which FWS had concerns are discussed in Section 2.2.8.1.
Environmental Impacts of Operation

4-27

1 The NRC sent a similar letter to the NMFS on February 16, 2011 (NRC 2011h). The NMFS 

2 responded to this letter in an e-mail dated March 3, 2011 (NMFS 2011) and provided the NRC 

3 with a list of Federally listed species under its jurisdiction in Texas.

4 Table 4–14 provides the NRC’s ESA effect determinations for each Federally listed species 

5 identified in Section 2.2.8.1.

6 Table 4–14. Effect Determinations for Federally Listed Species

Species ESA Effect 

Determination Justification for Determination

Amphibians

Houston toad 

(Bufo houstonensis)

unlikely to 

adversely affect

The species potentially occurs on the STP 

site or along the t-line corridors, but the 

proposed action would not result in 

measurable or detectable impacts or reach 

the scale at which a take occurs.

San Marcos salamander 

(Eurycea nana) 

unlikely to 

adversely affect

The species potentially occurs on the STP 

site or along the t-line corridors, but the 

proposed action would not result in 

measurable or detectable impacts or reach 

the scale at which a take occurs.

Texas blind salamander 

(Typhlomolge rathbuni) 

unlikely to 

adversely affect

The species potentially occurs on the STP 

site or along the t-line corridors, but the 

proposed action would not result in 

measurable or detectable impacts or reach 

the scale at which a take occurs.

Arachnids

Robber Baron Cave meshweaver 

(Cicurina baronia) no effect

This species occurs in underground caves in 

counties through which the t-lines cross. 

However, t-line maintenance activities would 

not affect this species.

Madla Cave meshweaver 

(Cicurina madla) no effect

This species occurs in underground caves in 

counties through which the t-lines cross. 

However, t-line maintenance activities would 

not affect this species.

braken bat cave meshweaver 

(Cicurina venii) no effect

This species occurs in underground caves in 

counties through which the t-lines cross. 

However, t-line maintenance activities would 

not affect this species.

Government Canyon bat cave 

meshweaver 

(Cicurina vespera) 

no effect

This species occurs in underground caves in 

counties through which the t-lines cross. 

However, t-line maintenance activities would 

not affect this species.

Government Canyon bat cave 

spider 

(Neoleptoneta microps) 

no effect

This species occurs in underground caves in 

counties through which the t-lines cross. 

However, t-line maintenance activities would 

not affect this species.
Environmental Impacts of Operation

4-28

Species ESA Effect 

Determination Justification for Determination

Cokendolpher cave harvestman 

(Texella cokendolpheri) no effect

This species occurs in underground caves in 

counties through which the t-lines cross. 

However, t-line maintenance activities would 

not affect this species.

Birds

piping plover 

(Charadrius melodus) 

unlikely to 

adversely affect

The species occurs in the action area, but 

the proposed action would not result in 

measurable or detectable impacts or reach 

the scale at which a take occurs.

golden-cheeked warbler 

(Dendroica chrysoparia) 

unlikely to 

adversely affect

This species occurs in counties through 

which the t-lines cross. However, t-line 

maintenance would not result in any 

measurable or detectable impacts or reach 

the scale at which a take occurs.

northern aplomado falcon 

(Falco femoralis septentrionalis) 

unlikely to 

adversely affect

This species occurs Matagorda County and 

in counties through which the t-lines cross. 

However, continued STP site operation and 

maintenance and t-line maintenance would 

not result in any measurable or detectable 

impacts or reach the scale at which a take 

occurs.

whooping crane 

(Grus americana) 

unlikely to 

adversely affect

This species occurs Matagorda County and 

in counties through which the t-lines cross. 

However, continued STP site operation and 

maintenance and t-line maintenance would 

not result in any measurable or detectable 

impacts or reach the scale at which a take 

occurs.

Attwater’s greater prairie-chicken 

(Tympanuchus cupido attwateri) 

unlikely to 

adversely affect

This species occurs in counties through 

which the t-lines cross. However, t-line 

maintenance would not result in any 

measurable or detectable impacts or reach 

the scale at which a take occurs.

black-capped vireo 

(Vireo atricapilla) 

unlikely to 

adversely affect

This species occurs in counties through 

which the t-lines cross. However, t-line 

maintenance would not result in any 

measurable or detectable impacts or reach 

the scale at which a take occurs.

Crustaceans

Peck’s cave amphipod 

(stygobromus pecki) no effect

This species occurs in two underground 

springs: Comal Springs and Hueco Springs.

The t-lines do not cross or run near these 

springs.
Environmental Impacts of Operation

4-29

Species ESA Effect 

Determination Justification for Determination

Fish

fountain darter 

(Etheostoma fonticola) no effect

This species only occurs in the San Marcos 

and Comal rivers. T-line maintenance would 

not affect this species because none of the tlines crosses these rivers. 

San Marcos gambusia 

(Gambusia georgei) no effect

This species only occurs in the San Marcos 

River. T-line maintenance would not affect 

this species because none of the t-lines 

cross this river.

smalltooth sawfish 

(Pristis pectinata) no effect

The species does not occur in the Colorado 

River or any of the water bodies crossed by 

the t-lines.

largetooth smallfish 

(Pristis pristis) no effect

The species does not occur in the Colorado 

River or any of the water bodies crossed by 

the t-lines.

Insects

helotes mold beetle 

(Batrisodes venyivi) no effect

This species occurs in underground caves in 

counties through which the t-lines cross. 

However, t-line maintenance activities would 

not affect this species.

Comal Springs riffle beetle 

(Heterelmis comalensis) no effect

This species occurs in two underground 

springs: Comal Springs and Fern Bank 

Springs. The t-lines do not cross or run near 

these springs.

unnamed beetle 

(Rhadine exilis) no effect

This species occurs in underground caves in 

counties through which the t-lines cross. 

However, t-line maintenance activities would 

not affect this species.

unnamed beetle 

(Rhadine infernalis) no effect

This species occurs in underground caves in 

counties through which the t-lines cross. 

However, t-line maintenance activities would 

not affect this species.

Comal Springs dryopid beetle 

(Stygoparnus comalensis) no effect

This species occurs in surface water in two 

springs: Comal Springs and Fern Bank 

Springs. The t-lines do not cross or run near 

these springs.

Mammals

sei whale 

(Balaenoptera borealis) no effect

The species does not occur in the Colorado 

River or any of the water bodies crossed by 

the t-lines.

blue whale 

(Balaenoptera musculus) no effect

The species does not occur in the Colorado 

River or any of the water bodies crossed by 

the t-lines.
Environmental Impacts of Operation

4-30

Species ESA Effect 

Determination Justification for Determination

finback whale 

(Balaenoptera physalus) no effect

The species does not occur in the Colorado 

River or any of the water bodies crossed by 

the t-lines.

Gulf coast jaguarundi 

(Herpailurus yaguarondi cacomitli) no effect

The species does not occur on the STP site 

and is unlikely to occur along the t-line 

corridors due to habitat preferences.

ocelot 

(Leopardus pardalis) no effect

The species does not occur on the STP site 

and is unlikely to occur along the t-line 

corridors due to habitat preferences.

humpback whale 

(Megaptera novaeangliae) no effect

The species does not occur in the Colorado 

River or any of the water bodies crossed by 

the t-lines.

sperm whale 

(Physeter macrocephalus) no effect

The species does not occur in the Colorado 

River or any of the water bodies crossed by 

the t-lines.

West Indian manatee 

(Trichechus manatus) no effect

The species does not occur in the Colorado 

River or any of the water bodies crossed by 

the t-lines.

Plants

Navasota ladies’ tresses 

(Spiranthes parksii) no effect

This species occurs in small-scale canopy 

openings of forests. Thus, this species is 

unlikely to be in t-line corridors, and t-line 

maintenance would not affect the species.

Texas wild rice 

(Spiranthes parksii) no effect

This species is an aquatic plant found in the 

San Marcos River. T-line maintenance 

would not affect this species because none 

of the t-lines cross this river.

Reptiles

American alligator 

(Alligator mississipiensis) 

unlikely to 

adversely affect

This species occurs on the STP site and 

may occur along t-line corridors. However, 

continued STP site operation and 

maintenance and t-line maintenance would 

not result in any measurable or detectable 

impacts or reach the scale at which a take 

occurs.

loggerhead sea turtle 

(Caretta caretta) no effect The species does not occur in the action 

area.

green sea turtle

(Chelonia mydas) no effect The species does not occur in the action 

area.

leatherback sea turtle

(Dermochelys coriacea) no effect The species does not occur in the action 

area.

hawksbill sea turtle

(Eretmochelys imbricata) no effect The species does not occur in the action 

area.
Environmental Impacts of Operation

4-31

Species ESA Effect 

Determination Justification for Determination

Kemp’s ridley sea turtle

(Lepidochelys kempii) no effect The species does not occur in the action 

area.

1 Based on a review of the ER, the information provided by the FWS, and the NRC staff’s 

2 independent review of available information, the NRC staff concludes that the proposed license 

3 renewal would have no effect on 31 of the 41 Federally listed species that occur in Matagorda 

4 County or in one of the counties through which the transmission line corridors traverse. The 

5 NRC staff concludes that the proposed license renewal may affect, but is unlikely to adversely 

6 affect, the remaining 10 species. Of these 10 species, only the American alligator 

7 (Alligator mississippiensis) has been observed on the site since STP began operating. There 

8 are three amphibian and six bird species that have not been observed on the site but have the 

9 potential to occur in areas of suitable habitat on the STP site or along the transmission line 

10 corridors. Continued operation and maintenance of the site will not involve any new changes to 

11 operation (e.g., construction, refurbishment, or ground-disturbing activities) or changes to 

12 existing land use conditions in either natural or developed areas. Thus, continued operation of 

13 STP would have no direct or indirect adverse effects to these species. Furthermore, the 

14 continued operation of STP during the license renewal term would preserve the existing habitats

15 on the STP site. Therefore, this could result in beneficial effects to the 10 species discussed 

16 above. 

17 The majority of the transmission line corridors traverse agricultural and range lands, which 

18 require minimal maintenance activities. Thus, continued operation and maintenance of the 

19 transmission lines would not result in habitat alteration. Herbicide application could create 

20 potential adverse effects by exposing these species to chemicals. However, these effects 

21 would be insignificant (i.e., those impacts that would never reach the scale where a take might 

22 occur) or discountable (i.e., those impacts that cannot be meaningfully measured, detected, or 

23 evaluated). The NRC staff did not identify any adverse effects associated with either STP site 

24 operation and maintenance or transmission line corridor maintenance that could reasonably be 

25 attributed to the proposed license renewal. However, because these species have the potential 

26 to occur in the area, the NRC staff conservatively has concluded that the proposed action may 

27 affect, but is unlikely to adversely affect, these species.

28 Designated Critical Habitat Protected Under the Endangered Species Act. The STP site is in 

29 close proximity to four units of designated piping plover (Charadrius melodus) critical habitat, 

30 the closest of which lies 7 mi (11 km) south of the STP site boundary along the shoreline of 

31 West Matagorda Bay. Because continued operation and maintenance of the STP site would 

32 involve no onsite or offsite disturbances, the proposed license renewal would result in no direct 

33 or indirect effects to piping plover critical habitat. The transmission line corridors do not occur 

34 near any of the four parcels of designated critical habitat. Thus, the NRC staff concludes that 

35 the proposed license renewal would have no effect on designated piping plover critical habitat.

36 Proposed Species and Proposed Critical Habitat Protected Under the Endangered Species Act. 

37 The NRC staff did not identify any Federally proposed species or proposed critical habitat within 

38 the action area during its review. Additionally, in its correspondence with NRC, the FWS (2011) 

39 and NMFS (2011) did not identify any proposed species or proposed critical habitat. Thus, the 

40 NRC staff concludes that the proposed license renewal would have no effect on Federally 

41 proposed species or proposed critical habitat.

42 Species Designated as NMFS Species of Concern. Though some of the species of concern 

43 listed in Section 2.2.8.2 occur in Matagorda Bay, none of the species of concern in the vicinity of 
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1 STP occur in the Colorado River and would, therefore, not be impinged or entrained by STP 

2 cooling water intake or otherwise affected by the proposed license renewal. The NRC staff 

3 concludes that there is no adverse impact to any NMFS species of concern.

4 Species Protected Under the Bald and Golden Eagles Protection Act. Though bald eagles 

5 occur throughout the STP region, no known nests are in close proximity to any of the STP 

6 buildings, parking lots, or other structures that could be disturbed by ongoing human activity. 

7 Because the proposed license renewal does not involve construction or land disturbances, no 

8 bald eagle habitat would be affected by the proposed license renewal. The NRC staff 

9 concludes that there is no adverse impact to the bald eagle.

10 Species Protected Under the Migratory Bird Treaty Act. As discussed in Section 2.2.8.4, a 

11 variety of migratory birds inhabit the STP site and surrounding region. Because the proposed 

12 license renewal does not involve construction or land disturbances, no migratory birds would be 

13 affected by the proposed license renewal. The NRC staff concludes that there is no adverse 

14 impact to migratory birds.

15 Species Protected Under the Marine Mammal Protection Act. Section 2.2.8.5 discusses marine 

16 mammals in the vicinity of STP. None of these species occur in the Colorado River and would, 

17 therefore, not be impinged or entrained by STP cooling water intake or otherwise affected by the 

18 proposed license renewal. The NRC staff concludes that there is no adverse impact to any 

19 marine mammals.

Species Protected Under the Magnuson–Stevens Act

25 The NRC prepared an EFH assessment (NRC 2011c) as part of the review of the Units 3 and 4 

26 COL application review. The NRC staff included the Colorado River, Matagorda Bay, and the 

27 Gulf of Mexico in the scope of its analysis because construction activities for the proposed 

28 Units 3 and 4 would include barge traffic. In that EFH assessment, the NRC concluded that the 

29 proposed Units 3 and 4 would have minimal adverse effects on EFH. The NMFS concurred 

30 with this determination in April 2010 (NMFS 2010). Because the area that would be affected by 

31 the proposed license renewal is smaller than the affected area for the proposed STP, Units 3 

32 and 4, and would not require any construction or changes to current operation, the NRC staff 

33 concludes that the NRC’s EFH assessment for the proposed STP, Units 3 and 4 (NRC 2011c), 

34 bounds the analysis for the proposed license renewal of STP, and that there are no adverse 

35 impacts to any EFH species.

20 . Section 2.2.8.6 identifies species with 

21 essential fish habitat (EFH) with the potential to occur in the vicinity of STP. Of these species, 

22 ENSR (2008) collected the mangrove snapper and brown shrimp, white shrimp have been 

23 collected during ecological studies associated with STP, and white and brown shrimp have been 

24 collected during impingement or entrainment samples.

36 Species Protected Under State of Texas Statutes. Section 2.2.8.7 discusses species protected 

37 under Texas’s State Statutes. Some State-listed species may occur along the transmission line 

38 corridors. However, the minimal transmission line maintenance associated with the STP 

39 transmission lines is unlikely to affect any State-listed species. Because the transmission line 

40 corridors are well-established, continued maintenance will also not reduce or affect the amount 

41 or quality of available habitat. The NRC staff concludes that there are no adverse impacts to 

42 any State-listed species.

43 Conclusion. The NRC staff concludes that the impacts of the proposed STP license renewal on 

44 protected species and habitats would be SMALL, as defined by the NRC for the purposes of 

45 National Environmental Policy Act (NEPA) compliance.
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4.8

2 The human health issues applicable to South Texas Project are discussed below and listed in 

3 Table 4–15 for Category 1, Category 2, and uncategorized issues.

1 Human Health

4 Table 4–15. Human Health Issues. 

5 Table B-1 of Appendix B to Subpart A of 10 CFR Part 51 contains more information on these 

6 issues.

Issue GEIS Section Category

Radiation exposures to the public during refurbishment 3.8.1(a) 1

Occupational radiation exposures during refurbishment 3.8.2(a) 1

Microbiological organisms (occupational health) 4.3.6 1

Microbiological organisms (public health, for plants using lakes or 

canals or cooling towers or cooling ponds that discharge to a small 

river)

4.3.6 2 

Noise 4.3.7 1

Radiation exposures to public (license renewal term) 4.6.2 1

Occupation radiation exposures (license renewal term) 4.6.3 1

Electromagnetic fields—acute effects (electric shock) 4.5.4.1 2

Electromagnetic fields—chronic effects 4.5.4.2 Uncategorized

(a) Issues apply to refurbishment, an activity that STP does not plan to undertake.

Source: Table B–1 in Appendix B, Subpart A, to 10 CFR Part 51

7 4.8.1 Generic Human Health Issues

8 Category 1 issues applicable to STP in regard to human health impacts are listed in Table 4–15. 

9 STPNOC stated in its ER that it was not aware of any new and significant human health issues 

10 associated with the renewal of the STP operating license. The staff has not identified any new 

11 and significant information related to human health issues associated with the operation of STP, 

12 Units 1 and 2, during the period of license renewal as a result of its independent review of 

13 STPNOC’s ER, the site audit, and the scoping process. The NRC staff also reviewed other 

14 sources of information, such as applicable permits and data reports, as listed in the reference 

15 section of this SEIS chapter. Therefore, the NRC staff concludes that, for Category 1 human 

16 health issues, there would be no impact from nonradiological issues to the public or to workers 

17 during the renewal term beyond those discussed in the GEIS.

18 4.8.2 Radiological Impacts of Normal Operations

19 Category 1 issues applicable to STP in regard to radiological impacts are listed in Table 4–15. 

20 Regarding the potential for new and significant radiological information, STPNOC evaluated the 

21 issue of tritium contained in groundwater on the plant site and concluded that the tritium in 

22 groundwater would not preclude the water’s current or future use; therefore, the issue is not new 

23 and significant. The staff discusses groundwater monitoring for radioactivity later in this section. 

24 In its radiological evaluation, the NRC staff determined that the issue is not new and significant.
Environmental Impacts of Operation

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1 The staff has not identified any new and significant information related to human health issues 

2 associated with radiation exposures during its independent review of STPNOC’s ER, the site 

3 audit, and the scoping process. Therefore, the NRC staff concludes that there would be no 

4 impact from radiation exposures to the public or to workers during the renewal term beyond 

5 those discussed in the GEIS.

6 The findings in the GEIS are as follows:

7 • Radiation exposures to public (license renewal term)—Based on information 

8 in the GEIS, the NRC found that radiation doses to the public will continue at 

9 current levels associated with normal operations.

10 • Occupational exposures (license renewal term)—Based on information in the 

11 GEIS, the NRC found that projected maximum occupational doses during the 

12 license renewal term are within the range of doses experienced during 

13 normal operations and normal maintenance outages and would be well below 

14 regulatory limits.

15 According to the GEIS, the impacts to human health are SMALL, and additional plant-specific 

16 mitigation measures are unlikely to be sufficiently beneficial to warrant implementation. There 

17 are no Category 2 issues related to radiological impacts of routine operations.

18 The information presented below is a discussion of selected radiological programs conducted at 

19 STP.

South Texas Project Radiological Environmental Monitoring Program

30 An annual radiological environmental operating report is issued, which contains a discussion of 

31 the results of the monitoring program. The report contains data on the monitoring performed for 

32 the most recent year. The REMP collects samples of environmental media to measure the 

33 radioactivity levels that may be present. The media samples are representative of the radiation 

34 exposure pathways that may impact the public.

20 . STP conducts a 

21 Radiological Environmental Monitoring Program (REMP) to assess the radiological impact, if 

22 any, to its employees, the public, and the environment from the operations at STP, Units 1 

23 and 2. The REMP measures the aquatic, terrestrial, and atmospheric environment for 

24 radioactivity, as well as the ambient radiation. In addition, the REMP measures background 

25 radiation (i.e., cosmic sources, global fallout, and naturally occurring radioactive material, 

26 including radon). The REMP supplements the radioactive effluent monitoring program by 

27 verifying that any measurable concentrations of radioactive materials and levels of radiation in 

28 the environment are not higher than those calculated using the radioactive effluent release 

29 measurements and transport models.

35 The STP REMP is made up of four categories based on the exposure pathways to the public—

36 airborne, waterborne, ingestion, and direct radiation. The air is sampled in areas around STP 

37 by measuring the levels of radioactive iodine and particulate matter on filters. For the 

38 waterborne pathway, the water samples are taken from surface water, groundwater, and 

39 drinking water. Also included in this pathway are sediment samples taken from the MCR and 

40 the Colorado River. The ingestion pathway samples local broadleaf vegetation, agricultural 

41 products, and food products. The direct exposure pathway measures environmental radiation 

42 doses using thermoluminescent dosimeters.

43 In addition to the REMP, STP has an onsite Groundwater Protection Program designed to 

44 monitor the onsite plant environment for detection of leaks from plant systems and pipes 

45 containing radioactive liquid (STPNOC 2010). Additional information on the Groundwater 
Environmental Impacts of Operation 

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1 Protection Program is contained later in this section and in the Groundwater Quality section in 

2 Chapter 2 of this document.

3 The staff reviewed the STP annual radiological environmental operating reports for 2006 

4 through 2010 to look for any significant impacts to the environment or any unusual trends in the 

5 data (STP 2007a, 2008d, 2009a, 2010a, 2011a). A 5-year period provides a data set that 

6 covers a broad range of activities that occur at a nuclear power plant such as refueling outages, 

7 non-refueling outage years, routine operation, and years where there may be significant 

8 maintenance activities. Based on the staff’s review, no adverse trends (i.e., steadily increasing 

9 buildup of radioactivity levels) were observed, and the data showed that there was no 

10 measurable impact to the environment from operations at STP.

Tritium Groundwater Monitoring

13 In 2007, the NEI established a standard for monitoring and reporting radioactive isotopes in 

14 groundwater. This standard is contained in NEI 07-07, Industry Ground Water Protection 

15 Initiative—Final Guidance Document (NEI 2007). STPNOC implemented the recommendations 

16 of this industry standard and has broadened the Groundwater Monitoring Program to include 

17 samples collected near the nuclear plants. Results of STPNOC’s Groundwater Monitoring 

18 Program are contained in the annual REMP report submitted to the NRC in May of each year. 

19 These reports are available for review by the public through the ADAMS electronic reading room 

20 available through the NRC Web site. 

11 . Nuclear industry events involving tritium prompted STP to 

12 sample groundwater in the shallow aquifer near the nuclear plants in 2005.

21 In the 2010 REMP report, STPNOC reported that tritium was detected on site. The applicant’s 

22 evaluation shows that the positive results are likely due to the well’s location in an area that is 

23 influenced by the MCR. Other positive samples appear to be the result of discharges to the 

24 ground involving water previously considered non-radioactive since only trace quantities of 

25 tritium were measured. All groundwater sample containing tritium were below the EPA’s 

26 drinking water standard of 20,000 pCi/l (740 Becquerels per liter). Also, the data showed no 

27 impact to sources of drinking water. The water samples from the onsite drinking water source 

28 (a deep aquifer) and offsite sampling of the Colorado River showed only natural background 

29 radiation levels (STPNOC 2011a).

30 Based on its review of the applicant’s monitoring reports, the staff concludes that there are no 

31 significant impacts to human health associated with tritium in the groundwater at the STP site. 

32 The applicant’s Groundwater Protection Program will monitor the groundwater and report the 

33 results in its annual radiological environmental monitoring report. Also, NRC inspectors will 

34 periodically review STPNOC’s Groundwater Protection Program to ensure the program 

35 continues to be effective. Additional information on the applicant’s Groundwater Protection 

36 Program and tritium in groundwater are in Sections 2.2.5 and 4.4.3 of this SEIS.

Texas Department of State Health Services Environmental Monitoring Program

44 The staff reviewed the State’s environmental summary reports for 2005 through 2009 (the most 

45 recent report available at the time of the staff’s review) (TDSHS 2012). In each of the reports, 

46 the State concluded that the sample data indicated no release of radioactive material to the 

37 . The Texas 

38 Department of State Health Services (DSHS) performs its own independent environmental 

39 monitoring around the STP site and other nuclear facilities (i.e., research reactors, commercial 

40 users of radioactive material, and the U.S. Department of Energy’s (DOE’s) Pantex facility)

41 located in Texas. All analyses of environmental media (i.e., soil, air, water, and vegetation) are 

42 performed by its Laboratory Services Section. The State’s radiation branch performs the 

43 monitoring of direct radiation from a facility using TLDs.
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1 environment that exceeded the regulatory or license limits of the DSHS or any other agency 

2 such as the NRC or the DOE. 

South Texas Project Radioactive Effluent Release Program

14 The NRC staff reviewed the annual radioactive effluent release reports for 2006 through 2010 

15 (STPNOC 2007b, 2008e, 2009b, 2010d, 2011d). The review focused on the calculated doses 

16 to a member of the public from radioactive effluents released from STP. The doses were 

17 compared to the radiation protection standards in 10 CFR 20.1301 and the ALARA dose design 

18 objectives in Appendix I to 10 CFR Part 50.

3 . All nuclear plants were licensed 

4 with the expectation that they would release radioactive material to both the air and water during 

5 normal operation. However, NRC regulations require that radioactive gaseous and liquid 

6 releases from nuclear power plants must meet radiation dose-based limits specified in 

7 10 CFR Part 20 and the as low as is reasonably achievable (ALARA) criteria in Appendix I to 

8 10 CFR Part 50. Regulatory limits are placed on the radiation dose that members of the public 

9 can receive from radioactive effluents released by a nuclear power plant. In addition, nuclear 

10 power plants are required by 10 CFR 50.36(a) to submit an annual report to the NRC, which 

11 lists the types and quantities of radioactive effluents released into the environment. The 

12 radioactive effluent release reports are available for review by the public through the ADAMS 

13 electronic reading room available through the NRC Web site.

19 Dose estimates for members of the public are calculated based on radioactive gaseous and 

20 liquid effluent release data and atmospheric and aquatic transport models. The 2010 annual 

21 radioactive material release report (STPNOC 2011d) contains a detailed presentation of the 

22 radioactive discharges and the resultant calculated doses. The following summarizes the 

23 calculated dose to a member of the public located outside the STP site boundary from 

24 radioactive gaseous and liquid effluents released during 2010:

25 • The total-body dose to an offsite member of the public from STP Unit 1 

radioactive liquid effluents was 4.75x10-3 mrem (4.75x10-5 26 mSv) and 

7.75x10-3 mrem (7.75x10-5 27 mSv) for Unit 2, which is well below the 3 mrem 

28 (0.03 mSv) dose criterion in Appendix I to 10 CFR Part 50.

29 • The organ (GI-tract) dose to an offsite member of the public from STP Unit 1 

radioactive liquid effluents was 4.79x10-3 mrem (4.79x10-5 30 mSv) and 

7.78x10-3 mrem (7.78x10-5 31 mSv), which is well below the 10 mrem 

32 (0.10 mSv) dose criterion in Appendix I to 10 CFR Part 50.

33 • The air dose at the site boundary from gamma radiation in gaseous effluents 

from STP Unit 1 was 4.43x10-4 mrad (4.43x10-6 mGy) and 1.62x10-3 34 mrad 

(1.62x10-5 35 mGy) for Unit 2, which is well below the 10 mrad (0.1 mGy) dose 

36 criterion in Appendix I to 10 CFR Part 50.

37 • The air dose at the site boundary from beta radiation in gaseous effluents 

from Unit 1 was 2.02x10-4 mrad (2.02x10-6 mGy) and 2.01x10-3 38 mrad 

(2.01x10-5 39 mGy) for Unit 2, which is well below the 20 mrad (0.2 mGy) dose 

40 criterion in Appendix I to 10 CFR Part 50.

41 • The dose to an organ (bone) from radioactive iodine, radioactive particulates, 

and carbon-14 from Unit 1 was 2.62x10-1 mrem (2.62x10-3 42 mSv) and 

2.66x10-1 mrem (2.66x10-1 43 mSv) for Unit 2, which is well below the 15 mrem 

44 (0.15 mSv) dose criterion in Appendix I to 10 CFR Part 50.
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1 • The highest dose from direct radiation, as measured by TLDs, to an offsite 

2 member of the public was 0.65 mrem (0.0065 mSv). This dose is based on a 

3 conservative assumption that an individual is located at the STP site fence 

4 east of the two reactor units for the entire year.

5 • The staff summed the applicant’s data on the individual total body doses from 

6 radioactive gaseous and liquid effluents from both units and added it to the 

7 dose from direct radiation to obtain the maximum all pathways dose to an 

8 offsite member of the public from the operation of STP, Units 1 and 2. The all 

9 pathways annual dose is 0.67 mrem (0.0067 mSv), which is well below the 

10 25 mrem (0.25 mSv) dose standard in EPA’s 40 CFR Part 190.

11 The staff’s review of the STP Radioactive Effluent Control Program showed that radiation doses 

12 to members of the public were controlled within Federal radiation protection standards 

13 contained in Appendix I to 10 CFR Part 50, 10 CFR Part 20, and 40 CFR Part 190.

14 The applicant has no plans to conduct refurbishment activities during the license renewal term; 

15 however, routine plant refueling and maintenance activities currently performed will continue 

16 during the license renewal term. Based on the past performance of the radioactive waste 

17 system to maintain the dose from radioactive effluents to be ALARA, similar performance is 

18 expected during the license renewal term. Continued compliance with regulatory requirements 

19 is expected during the license renewal term; therefore, the impacts from radioactive effluents 

20 would be SMALL.

21 4.8.3 Microbiological Organisms

22 For power plants that use a cooling pond, lake, or canal or that discharge to a small river, the 

23 effects of microbiological organisms on human health are listed as a Category 2 issue and 

24 require plant-specific evaluation for license renewal review. This issue is applicable to STP 

25 because the facility uses a cooling pond, as defined in the GElS (NRC 1996). The cooling pond 

26 (MCR) discharges to Colorado River that has the mean annual average flow of approximately 

27 2,629 cfs (NRC 2011b). This meets the definition of a small river. The MCR is within the 

28 confine of the STP security perimeter and is not available for public use.

29 The Category 2 designation is based on the potential for public health impacts associated with 

30 thermal enhancement of Naegleria fowleri, a pathogenic amoeba, and other enteric pathogens 

31 that could not be assessed generically. The NRC noted that impacts of nuclear plant thermal 

32 discharges are considered to be of small significance if they do not enhance the presence of 

33 microorganisms that are detrimental to water quality and public health (NRC 1996).

34 Microbiological organisms that grow at temperatures above 45 °C to 50 °C (113 °F to 122 °F) 

35 are termed thermophilic, or heat-loving, organisms (Brock 1974). STP has TPDES permit 

36 (No. WQ0001908000) to discharge to the Colorado at the daily average temperature limit of 

37 95 °F and daily maximum temperature limit of 97 °F (STPNOC 2010). These limits are below 

38 the temperature at which thermophilic microorganisms grow and thrive (113 °F to 122 °F). 

39 Hence, the potential of waterborne disease outbreak due to discharge from the MCR to the 

40 Colorado River is remote.

41 Furthermore, the TPDES permit limits the discharge to less than 12.5 percent of the river flow 

42 and may not exceed 200 million gpd. It is likely that the discharge would occur during high river 

43 flow periods, which are reported by the STPNOC to be during the winter and spring when the 

44 river temperature is at low level.
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1 The staff asked the Texas Department of Health about any concerns the department might have 

2 relative to the microorganisms in the MCR that could cause waterborne disease outbreak in the 

3 area (NRC 2012). The department responded that it did not have any records of such outbreak, 

4 and it is not aware of any potential concerns about outbreaks associated with the operation of 

5 STP during the extended period of operation.

6 The staff concludes that the potential impacts to public health from microbiological organisms, 

7 resulting from operation of the STP cooling water discharge system to the aquatic environment 

8 on or near the site, are SMALL, and no further mitigations are warranted.

9 4.8.4 Electromagnetic Fields—Acute Effects

10 Based on the GEIS, the NRC found that electric shock resulting from direct access to energized 

11 conductors or from induced charges in metallic structures has not been found to be a problem at 

12 most operating plants and, generally, is not expected to be a problem during the license renewal 

13 term. However, site-specific review is required to determine the significance of the electric 

14 shock potential along the portions of the transmission lines that are within the scope of this 

15 SEIS.

16 In the GEIS (NRC 1996), the NRC found that without a review of the conformance of each 

17 nuclear plant transmission line with National Electrical Safety Code (NESC) criteria, it was not 

18 possible to determine the significance of the electric shock potential (IEEE 2002). Evaluation of 

19 individual plant transmission lines is necessary because the issue of electric shock safety was 

20 not addressed in the licensing process for some plants. For other plants, land use in the vicinity 

21 of transmission lines may have changed, or power distribution companies may have chosen to 

22 upgrade line voltage. To comply with 10 CFR 51.53(c)(3)(ii)(H), the applicant must provide an 

23 assessment of the impact of the proposed action on the potential shock hazard from the 

24 transmission lines if the transmission lines that were constructed for the specific purpose of 

25 connecting the plant to the transmission system do not meet the recommendations of the NESC 

26 for preventing electric shock from induced currents.

27 STPNOC analyzed its transmission lines to identify the limiting case for each line where the 

28 potential exists for the highest current-induced shock. STPNOC calculated the electric field 

29 strength and induced current for each of the lines using a computer code called ACDCLINE, 

30 produced by the Electric Power Research Institute. The input parameters included the design 

31 features of each of the limiting-case transmission lines, and a tractor-trailer was assumed to be 

32 the maximum vehicle size under the lines. STPNOC reported in its ER and in two supplemental 

33 letters (STPNOC 2011c, 2011f) that there are three transmission lines (i.e., two Hill County lines 

34 and one Skyline line) that exceed the NESC 5 milliampere (mA) criterion for preventing electric 

35 shock from induced currents. However, STPNOC states that the configuration of these lines 

36 has changed since the original plant construction. These lines are no longer directly connected 

37 with STP. A substation was constructed at Elm Creek. The original Hill County and Skyline 

38 transmission lines are now looped into the Elm Creek substation before proceeding to the Hill 

39 County and Skyline substations. The lines pass through land that is primarily agricultural and 

40 rangeland, with some forest land and lesser land-use categories. The areas are mostly remote, 

41 with low population densities. The lines cross numerous county, State, and U.S. highways.

42 As reported by STPNOC in its ER, the service providers for the STP transmission lines have 

43 surveillance and maintenance procedures that periodically examine the lines to ensure they 

44 remain within their design criteria. These procedures include routine aerial inspections that 

45 include checks for encroachments, broken conductors, broken or leaning structures, and signs 

46 of trees burning, any of which would be evidence of clearance problems. Ground inspections 
Environmental Impacts of Operation

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1 include examination for clearance, integrity of structures, and surveillance for dead or diseased 

2 trees that might fall on the transmission lines. Problems noted during any inspection are 

3 reported for follow-up corrective action. STPNOC has considered potential mitigation measures 

4 to reduce or avoid adverse impacts from electric shock from its transmission lines, with a 

5 combination of options, as follows:

6 • re-examining the induced current calculations for selected transmission lines

7 (for accuracy and possible safety margin identification), 

8 • raising the transmission towers at the potentially affected road-transmission 

9 line intersections,

10 • modifying the double-circuit lines to reduce the current-induced shock 

11 potential, or

12 • placing caution signs under the transmission lines.

13 Based on information provided by STPNOC and potential mitigation measures (to reduce or 

14 avoid adverse impacts) considered by the applicant, the staff concludes that potential impact 

15 from acute electric shock during the renewal period would be SMALL to MODERATE. This 

16 conclusion is based on the fact that the three transmission lines exceed the NESC 5 mA 

17 criterion by a small percentage, the locations where the lines exceed the standard are in remote 

18 locations or are on private property, and the applicant, in accordance with 

19 10 CFR 51.53(c)(3)(iii), has considered potential mitigation measures to reduce or avoid 

20 adverse impacts from electric shock.

21 4.8.5 Electromagnetic Fields—Chronic Effects

22 In the GEIS, the effects of chronic exposure to 60 Hz electromagnetic fields from powerlines 

23 were not designated as Category 1 or 2 and will remain uncategorized until a scientific 

24 consensus is reached on the health implications of these fields.

25 The potential effects of chronic exposure from these fields continue to be studied and are not 

26 known at this time. The National Institute of Environmental Health Sciences (NIEHS) directs 

27 related research through the DOE.

28 The NIEHS report (NIEHS 1999) contains the following conclusion:

29 The NIEHS concludes that ELF EMF (extremely low frequency electromagnetic 

30 field) exposure cannot be recognized as entirely safe because of weak scientific 

31 evidence that exposure may pose a leukemia hazard. In our opinion, this finding 

32 is insufficient to warrant aggressive regulatory concern. However, because 

33 virtually everyone in the United States uses electricity and therefore is routinely 

34 exposed to ELF EMF, passive regulatory action is warranted such as continued 

35 emphasis on educating both the public and the regulated community on means 

36 aimed at reducing exposures. The NIEHS does not believe that other cancers or 

37 non cancer health outcomes provide sufficient evidence of a risk to currently 

38 warrant concern.

39 This statement is not sufficient to cause the staff to change its position with respect to the 

40 chronic effects of electromagnetic fields. The staff considers the GEIS finding of “UNCERTAIN” 

41 still appropriate and will continue to follow developments on this issue. 
Environmental Impacts of Operation

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4.9

2 The socioeconomic issues applicable to STP, Units 1 and 2, are shown in Table 4–16 for 

3 Category 1, Category 2, and one uncategorized issue (environmental justice). Section 2.2.8 of 

4 this SEIS describes the socioeconomic conditions near STP, Units 1 and 2.

1 Socioeconomics

5 Table 4–16. Socioeconomics during the Renewal Term

Issues GEIS Section Category

Housing impacts 4.7.1 2

Public services: public safety, social services, & tourism & 

recreation

4.7.3, 4.7.3.3, 4.7.3.4, 

4.7.3.6 1 

Public services: public utilities 4.7.3.5 2

Public services: education (license renewal) 4.7.3.1 1

Offsite land use (license renewal term) 4.7.4 2

Public Services: transportation 4.7.3.2 2 

Historic & archaeological resources 4.7.7 2 

Aesthetic impacts (license renewal term) 4.7.6 1 

Aesthetic impacts of transmission lines (license renewal term) 4.5.8 1

Environmental justice Not addressed(a) Uncategorized

(a) Guidance for implementing Executive Order 12898 and conducting an environmental justice impact analysis was 

not available prior to the completion of the GEIS. This issue must be addressed in plant-specific reviews.

6 4.9.1 Generic Socioeconomic Issues

7 The STPNOC ER, scoping comments, other available data records on STP, Units 1 and 2, were 

8 reviewed and evaluated for new and significant information. The review included a data 

9 gathering site visit to STP, Units 1 and 2 (the NRC staff also reviewed other sources of 

10 information such as applicable permits and data reports as listed in the reference section of this 

11 SEIS chapter). No new and significant information was identified during this review that would 

12 change the conclusions presented in the GEIS. Therefore, for these Category 1 issues, impacts 

13 during the renewal term are not expected to exceed those discussed in the GEIS. For STP, 

14 Units 1 and 2, the NRC staff incorporates the GEIS conclusions by reference. Impacts for 

15 Category 2 issues and the uncategorized issue (environmental justice) are discussed in 

16 Sections 4.9.2 through 4.9.7.

17 4.9.2 Housing

18 Appendix C of the GEIS (NRC 1996) presents a population characterization method based on 

19 two factors—sparseness and proximity. Sparseness measures population density within 20 mi

20 (32 km) of the site, and proximity measures population density and city size within 50 mi

21 (80 km). Each factor has categories of density and size. A matrix is used to rank the population 

22 category as low, medium, or high as shown in Figure C.1 of the GEIS. 

23 According to the 2000 Census, an estimated 35,291 people lived within 20 mi (32 km) of STP, 

24 Units 1 and 2, which equates to a population density of 36 persons per square mile 
Environmental Impacts of Operation

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1 (STPNOC 2010). This translates to a Category 1, “most sparse,” population density using the 

2 GEIS measure of sparseness (less than 40 persons per square mile and no community with 

3 25,000 or more people within 20 mi). An estimated 255,118 people live within 50 mi (80 km) of 

4 STP, Units 1 and 2, with a population density of 32 persons per square mile (STPNOC 2010). 

5 Applying the GEIS proximity measures, STP is classified as proximity Category 1 (no city with 

6 100,000 or more persons and less than 50 persons per square mile within 50 mi). Therefore, 

7 according to the sparseness and proximity matrix presented in the GEIS, rankings of 

8 sparseness Category 1 and proximity Category 1 result in the conclusion that the STP is located 

9 in a low population area.

10 Table B-1 of 10 CFR Part 51, Subpart A, Appendix B, states that impacts on housing availability 

11 are expected to be of SMALL, MODERATE, or LARGE. MODERATE or LARGE housing 

12 impacts of the workforce associated with refurbishment may be associated with plants located in 

13 sparsely populated areas or in areas with growth control measures that limit housing 

14 development. Because (a) STPNOC has no planned refurbishment activities and (b) Brazoria 

15 County and Matagorda County are not subject to growth-control measures that would limit 

16 housing development, any changes in employment at STP would have little noticeable effect on 

17 housing availability in these counties. Since STPNOC has no plan to add non-outage 

18 employees during the license renewal period, employment levels at STP would remain relatively 

19 constant with no additional demand for permanent housing during the license renewal term. 

20 Based on this information, there would be no additional impact on housing during the license 

21 renewal term beyond what has already been experienced. Because there is no additional 

22 impact, the impact is considered to be SMALL (not MODERATE or LARGE).

23 4.9.3 Public Services—Public Utilities

24 Impacts on public utility services (e.g., water, sewer) are considered SMALL if the public utility 

25 has the ability to respond to changes in demand and would have no need to add or modify 

26 facilities. Impacts are considered MODERATE if service capabilities are overtaxed during 

27 periods of peak demand. Impacts are considered LARGE if additional system capacity is 

28 needed to meet ongoing demand.

29 Analysis of impacts on the public water systems considered both plant demand and 

30 plant-related population growth. Section 2.1.7 of this SEIS describes the permitted withdrawal 

31 rate and actual use of water for reactor cooling at STP, Units 1 and 2.

32 Since STPNOC has no plans to add non-outage employees during the license renewal period, 

33 employment levels at STP would remain relatively unchanged with no additional demand for 

34 public water services. Public water systems in the region are adequate to meet the demands of 

35 residential and industrial customers in the area. Therefore, there would be no additional impact 

36 to public water services during the license renewal term beyond what is currently being

37 experienced. Because there is no additional impact, the impact is considered to be SMALL (not 

38 MODERATE or LARGE).

39 4.9.4 Public Services—Transportation

40 Table B-1 of Appendix B to Subpart A of 10 CFR Part 51 states that: 

41 Transportation impacts (level of service) of highway traffic generated...during the 

42 term of the renewed license are generally expected to be of SMALL significance. 

43 However, the increase in traffic associated with additional workers and the local 

44 road and traffic control conditions may lead to impacts of MODERATE or LARGE 

45 significance at some sites.
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1 The regulation in 10 CFR 51.53(c)(3)(ii)(J) requires all applicants to assess the impacts of 

2 highway traffic generated by the proposed project on the level of service of local highways 

3 during the term of the renewed license. Since STPNOC has no plans to add non-outage 

4 employees during the license renewal period, traffic volume and levels of service on roadways 

5 in the vicinity of STP, Units 1 and 2, would not change. Therefore, there would be no 

6 transportation impacts during the license renewal term beyond those already being 

7 experienced. Because there is no additional impact, the impact is considered to be SMALL (not 

8 MODERATE or LARGE).

9 4.9.5 Offsite Land Use

10 Table B-1 of Appendix B to Subpart A of 10 CFR Part 51 notes that “significant changes in land 

11 use may be associated with population and tax revenue changes resulting from license 

12 renewal.” Section 4.7.4 of the GEIS defines the magnitude of land-use changes as a result of 

13 plant operation during the license renewal term as SMALL when there will be little new 

14 development and minimal changes to an area’s land-use pattern, as MODERATE when there 

15 will be considerable new development and some changes to the land-use pattern, and LARGE 

16 when there will be large-scale new development and major changes in the land-use pattern.

17 Tax revenue can affect land use because it enables local jurisdictions to provide the public 

18 services (e.g., transportation and utilities) necessary to support development. Section 4.7.4.1 of 

19 the GEIS states that the assessment of tax-driven land-use impacts during the license renewal 

20 term should consider the size of the plant’s tax payments relative to the community’s total 

21 revenues, the nature of the community’s existing land-use pattern, and the extent to which the 

22 community already has public services in place to support and guide development. If the plant’s 

23 tax payments are projected to be small relative to the community’s total revenue, tax driven 

24 land-use changes during the plant’s license renewal term would be SMALL, especially where 

25 the community has pre-established patterns of development and has provided public services to 

26 support and guide development. Section 4.7.2.1 of the GEIS states that if tax payments by the 

27 plant owner are less than 10 percent of the taxing jurisdiction’s revenue, the significance level 

28 would be SMALL. If tax payments are 10 to 20 percent of the community’s total revenue, new 

29 tax-driven land-use changes would be MODERATE. If tax payments are greater than 

30 20 percent of the community’s total revenue, new tax-driven land-use changes would be 

31 LARGE. This would be especially true where the community has no pre-established pattern of 

32 development or has not provided adequate public services to support and guide development.

33 4.9.5.1 Population-Related Impacts

34 Since STPNOC has no plans to add non-outage employees during the license renewal period, 

35 there would be no plant operations-driven population increase in the vicinity of STP, Units 1 

36 and 2. Therefore, there would be no additional population-related offsite land use impacts 

37 during the license renewal term beyond those already being experienced.

38 4.9.5.2 Tax Revenue-Related Impacts

39 As discussed in Chapter 2, STPNOC pays property taxes for STP, Units 1 and 2, to Matagorda 

40 County, Matagorda County Hospital District, Navigation District #1, Drainage District #3, 

41 Palacios Seawall District, and the Coastal Plains Groundwater District. Since STPNOC started 

42 making property tax payments to local jurisdictions, population levels and land use conditions in 

43 Matagorda County has remained relatively unchanged (STPNOC 2010); therefore, tax revenue 

44 from STP, Units 1 and 2, has had little or no effect on land use conditions within the county.
Environmental Impacts of Operation

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1 Since employment levels at STP, Units 1 and 2, would remain relatively unchanged with no 

2 increase in the assessed value of STP, Units 1 and 2, annual property tax payments would also 

3 be expected to remain relatively unchanged throughout the license renewal period. Based on 

4 this information, there would be no additional tax-revenue-related offsite land use impacts 

5 during the license renewal term beyond those already being experienced. Because there is no 

6 additional impact, the impact is considered to be SMALL (not MODERATE or LARGE).

7 4.9.6 Historic and Archaeological Resources

8 The National Historic Preservation Act (NHPA) requires Federal agencies to consider the effects 

9 of their undertakings on historic properties. Historic properties are defined as resources that are 

10 eligible for listing on the National Register of Historic Places (NRHP). The criteria for eligibility 

11 are listed in 36 CFR 60.4 and include association with significant events in history; association 

12 with the lives of persons significant in the past; embodiment of distinctive characteristics of type, 

13 period, or construction; and sites or places that have yielded or are likely to yield important 

14 information. The historic preservation review process (Section 106 of NHPA) is outlined in 

15 regulations issued by the Advisory Council on Historic Preservation (ACHP) in 36 CFR Part 800. 

16 In accordance with 36 CFR 800.8(c), the NRC has elected to use the NEPA process to comply 

17 with the obligations found under Section 106 of the NHPA.

18 The issuance of a renewed operating license for a nuclear power plant is a Federal action that 

19 could affect historic properties on or near the nuclear plant site and transmission lines. In 

20 accordance with the provisions of the NHPA, the NRC is required to make a reasonable effort to 

21 identify historic properties included in or eligible for inclusion in the NRHP in the area of 

22 potential effect (APE). The APE for license renewal is the nuclear power plant site, 

23 transmission lines, and immediate environs. If historic properties are present, the NRC is 

24 required to contact the State Historic Preservation Office (SHPO), assess the potential impact, 

25 and resolve any possible adverse effects of the undertaking (license renewal) on historic 

26 properties. NRC is also required to notify the SHPO if historic properties would not be affected 

27 by license renewal or if no historic properties are present. The SHPO is part of the Texas 

28 Historical Commission (THC) in the State of Texas. This section provides the NRC’s 

29 assessment of effects from the proposed license renewal action for STP, Units 1 and 2. 

30 Section 2.2.10 of this SEIS provides specific historic and cultural information near the STP site.

31 On March 17, 2009, STP initiated informal consultation with the THC regarding the renewal of 

32 operating licenses for STP, Units 1 and 2. STP concluded in its letter to THC that there would 

33 be no effect on historic properties from license renewal and associated operation and 

34 maintenance activities (STPNOC 2010b). The THC responded to STP on October 26, 2009, 

35 with a determination of “No Historic Properties Affected, Project May Proceed” 

36 (STPNOC 2010b). The THC response is in the form of a stamp on the last page of the STP 

37 letter that was sent to the THC, which STP included in its ER for license renewal 

38 (STPNOC 2010b).

39 Prior to the site audit in May 2011, NRC contacted the THC concerning license renewal for STP. 

40 The staff and THC concluded there was no need to meet during the environmental audit to 

41 discuss cultural resources (NRC 2011a). The THC determined that there were no known issues 

42 with license renewal for STP and referred the NRC to the THC response to STP on 

43 October 26, 2009, with the determination of “No Historic Properties Affected, Project May 

44 Proceed” (STPNOC 2010b).

45 In accordance with 36 CFR 800.8(c), on January 27, 2011, and February 17, 2011, respectively, 

46 the NRC initiated consultations on the proposed action by writing to the ACHP and SHPO 
Environmental Impacts of Operation

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1 (NRC 2011d, 2011e). In February 2011, the NRC initiated consultation with six Federally 

2 recognized tribes: the Yselta del Sur Pueblo Tribe, Alabama-Cousahatta Tribe, Kiowa Tribe of 

3 Oklahoma, the Comanche Nation, Tonkawa Tribe of Oklahoma, and Kickapoo Traditional 

4 Council (Appendix D contains a copy of these letters for reading convenience). Also in 

5 February 2011, the NRC initiated consultation with four additional tribes: the Apalachicola Band 

6 of Creek Indians, Lipan Apache Band of Texas, Pamaque Clan of Coahuila Y Tejas, and the 

7 Tap Pilam-Coahuiltecan Nation (Appendix D contains a copy of these letters). In its letters, the 

8 NRC provided information about the proposed action and the definition of APE. In addition, the 

9 NRC indicated that the NHPA review would be integrated with the NEPA process, in 

10 accordance with 36 CFR 800.8. NRC invited participation in the identification and possible 

11 decisions concerning historic properties and invited participation in the scoping process. Four 

12 tribes—the Apalachicola Band of Creek Indians, the Kickapoo Traditional Council, the Tonkawa 

13 Tribe of Oklahoma, and the Tap Pilam-Coahuiltecan Nation—responded to the NRC with 

14 scoping comments. These comments included concerns with potential accidents, requests to 

15 re-survey the STP site, requests for notification if historic and cultural resources of cultural 

16 significance were discovered on the STP site, and statements of no concern with the 

17 undertaking. NRC responded to the tribes in October 2011 and has taken the comments into 

18 consideration while preparing this SEIS (Appendix D lists copies of these letters). 

19 As described in Section 2.2.10, there are no recorded archaeological sites or historic structures 

20 on the STP site. STPNOC has identified a potential historic gravesite located on the southeast

21 boundary of the STP site within the APE. STP staff interviewed descendants of the former 

22 property owner and confirmed the presence of a grave from the late 1800s; however, little is 

23 known about the gravesite, and it is not a recorded historic and archaeological resource. The 

24 NRC staff has confirmed that there are no planned ground-disturbing activities near the 

25 gravesite and it would be protected from any operation and maintenance activities associated 

26 with the license renewal term as the activities “would occur several miles from the [grave]site 

27 and would be conducted in accordance with STP environmental compliance procedures” 

28 (STPNOC 2011g). 

29 STPNOC has no planned refurbishment activities associated with license renewal at the STP 

30 site (STPNOC 2011g). A review of operation and maintenance activities that occur in and 

31 around the STP site indicates that these activities are limited to the use of existing roads and 

32 previously disturbed areas and are subject to STP environmental compliance procedures

33 (applicable to any future potential land disturbing constructions at STP). 

34 For the purposes of NHPA Section 106 consultation, the NRC staff concludes a finding of no 

35 effect to historic properties (36 CFR Section 800.4(d)(1)) based on the following:

36 • historic and cultural resources located within the APE, 

37 • tribal input, 

38 • STP environmental compliance procedures, 

39 • there will be no refurbishment or ground-disturbing activities associated with 

40 the relicensing of STP, Units 1 and 2,

41 • SHPO finding of “No Historic Properties—Affected, Project May Proceed,” 

42 and 

43 • the NRC staff’s cultural resource analysis and consultation. 
Environmental Impacts of Operation

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1 For the purposes of the NRC staff’s NEPA analysis, in consideration of the conclusion reached 

2 in the NHPA Section 106 consultation, the NRC staff concludes that potential impacts on 

3 historic and cultural resources related to STP license renewal would be SMALL.

4 4.9.7 Environmental Justice

5 Under Executive Order (EO) 12898 (59 FR 7629), Federal agencies are responsible for 

6 identifying and addressing, as appropriate, disproportionately high and adverse human health 

7 and environmental impacts on minority and low-income populations. In 2004, the NRC issued a 

8 Policy Statement on the Treatment of Environmental Justice Matters in NRC Regulatory and 

9 Licensing Actions (69 FR 52040), which states, “The Commission is committed to the general 

10 goals set forth in EO 12898, and strives to meet those goals as part of its NEPA review 

11 process.” 

12 The Council on Environmental Quality (CEQ) provides the following information in 

13 Environmental Justice: Guidance Under the National Environmental Policy Act (CEQ 1997):

14 Disproportionately High and Adverse Human Health Effects.

15 Adverse health effects are measured in risks and rates that could result in latent 

16 cancer fatalities, as well as other fatal or nonfatal adverse impacts on human 

17 health. Adverse health effects may include bodily impairment, infirmity, illness, or 

18 death. Disproportionately high and adverse human health effects occur when the 

19 risk or rate of exposure to an environmental hazard for a minority or low-income 

20 population is significant (as employed by NEPA) and appreciably exceeds the 

21 risk or exposure rate for the general population or for another appropriate 

22 comparison group.

23 Disproportionately High and Adverse Environmental Effects.

24 A disproportionately high environmental impact that is significant (as employed 

25 by NEPA) refers to an impact or risk of an impact on the natural or physical 

26 environment in a low-income or minority community that appreciably exceeds the 

27 environmental impact on the larger community. Such effects may include 

28 ecological, cultural, human health, economic, or social impacts. An adverse 

29 environmental impact is an impact that is determined to be both harmful and 

30 significant (as employed by NEPA). In assessing cultural and aesthetic 

31 environmental impacts, impacts that uniquely affect geographically dislocated or 

32 dispersed minority or low-income populations or American Indian tribes are 

33 considered.

34 The environmental justice analysis assesses the potential for disproportionately high and 

35 adverse human health or environmental effects on minority and low-income populations that 

36 could result from the operation of STP during the license renewal term. In assessing the 

37 impacts, the following definitions of minority individuals and populations and low-income 

38 population were used (CEQ 1997):

39 Minority individuals.

40 Individuals who identify themselves as members of the following population 

41 groups: Hispanic or Latino, American Indian or Alaska Native, Asian, Black or 

42 African American, Native Hawaiian or Other Pacific Islander, or two or more 

43 races, meaning individuals who identified themselves on a Census form as being 

44 a member of two or more races, for example, Hispanic and Asian.

45

46
Environmental Impacts of Operation

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1 Minority populations.

2 Minority populations are identified when (1) the minority population of an affected 

3 area exceeds 50 percent or (2) the minority population percentage of the affected 

4 area is meaningfully greater than the minority population percentage in the 

5 general population or other appropriate unit of geographic analysis.

6 Low-income population.

7 Low-income populations in an affected area are identified with the annual 

8 statistical poverty thresholds from the Census Bureau’s Current Population 

9 Reports, Series P60, on Income and Poverty.

Minority Population

15 According to 2010 Census data, minority populations in the socioeconomic ROI (Matagorda and 

16 Brazoria Counties) comprised 47.4 percent of the total two-county population as shown in 

17 Table 2–17 (USCB 2011). Figure 4–2 shows minority population block groups using 

18 2010 Census data for race and ethnicity within a 50-mi (80-km) radius of STP.

10 . According to 2010 Census data, 45.9 percent of the total population 

11 (approximately 110,201 persons) residing within a 50-mi (80-km) radius of STP identified 

12 themselves as minority individuals. The largest minority group was Hispanic or Latino (of any 

13 race) (approximately 82,000 persons or 33.9 percent), followed by Black or African American 

14 (approximately 23,000 persons or 9.6 percent) (CAPS 2011).
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1 Figure 4–2. 2010 Census Minority Block Groups Within a 50-mi Radius of STP

Source: USCB 2012.
Environmental Impacts of Operation

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1 Census block groups were considered minority population block groups if the percentage of the 

2 minority population within any block group exceeded 45.9 percent (the percent of the minority 

3 population within the 50-mi radius of STP). A minority population exists if the percentage of the 

4 minority population within the block group is meaningfully greater than the minority population 

5 percentage in the 50-mi radius. Minority population block groups are concentrated in the Bay 

6 City area, El Campo, Freeport, Palacios, and Port Lavaca. Smaller concentrations of minority 

7 population block groups are found in Angelton and Wharton. The nearest minority population 

8 (i.e., percentage is meaningfully greater than the percentage in the 50-mi radius) to STP is 

9 located in Matagorda, Texas. In Matagorda, according to the 2010 Census, approximately 

10 15 percent of the Matagorda population identified themselves as minority.

Low-Income Population

17 According to 2006 through 2010 American Community Survey 5-year estimates, the median 

18 household income for Texas was $49,646, with 16.8 percent of the State population and 

19 13 percent of families living below the Federal poverty threshold in 2010 (USCB 2011). 

20 Brazoria County had a lower median household income average ($43,258) and 

21 lower percentages of individuals (10.6 percent) and families (8.2 percent) living below the 

22 poverty level when compared to the State average. Matagorda County had a lower household 

23 income average ($48,508) compared to the State average and higher than Brazoria County, but 

24 a higher percentage of individuals (18.6 percent) and families (21.6 percent) living below the 

25 poverty level when compared to Brazoria County and the State (USCB 2011).

11 . According to 2006 through 2010 American Community Survey 5-year 

12 estimates, an average of 11.4 percent of families and 14.2 percent of individuals residing in nine 

13 counties—all or parts of which are located within a 50-mi radius of STP (Brazoria, Calhoun, 

14 Colorado, Fort Bend, Jackson, Lavaca, Matagorda, Victoria, and Wharton)—were identified as 

15 living below the Federal poverty threshold in 2010 (USCB 2010). The 2010 Federal poverty 

16 threshold was $22,314 for a family of four. 

26 Figure 4–3 shows low-income census block groups within a 50-mi (80-km) radius of STP. 

27 Census block groups were considered low-income population block groups if the percentage of 

28 individuals living below the Federal poverty threshold within any block group exceeded the 

29 percent of the individuals living below the Federal poverty threshold within the 50-mi radius of 

30 STP. Similar to the locations of minority population block groups, the majority of low-income 

31 population block groups are located in the Bay City area, Freeport, Palacios, Port Lavaca, and 

32 Wharton. Smaller concentrations of minority population block groups are located near Angelton. 

33 The nearest low-income population to STP is located in Matagorda, Texas.
Environmental Impacts of Operation

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1 Figure 4–3. Census 2010 Low-Income Block Groups Within a 50-mi Radius of STP

Source: USCB 2012
Environmental Impacts of Operation

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Analysis of Impacts

3 • identifying the location of minority and low-income populations that may be 

4 affected by the continued operation of the nuclear power plant during the 

5 license renewal term, 

1 . The NRC addresses environmental justice matters for license renewal in 

2 the following ways:

6 • determining whether there would be any potential human health or 

7 environmental effects to these populations and special pathway receptors, 

8 and

9 • determining if any of the effects may be disproportionately high and adverse.

10 Figure 4–2 and Figure 4–3, above, identify the location of minority and low-income populations 

11 residing within a 50-mi (80-km) radius of STP. This area of impact is consistent with the impact 

12 analysis for public and occupational health and safety, which also focuses on populations within 

13 a 50-mi (80-km) radius of the nuclear plant. Chapter 4 presents the assessment of 

14 environmental and health impacts for each resource area. The analyses of impacts for all 

15 environmental resource areas indicated that the impact from license renewal would be SMALL.

16 Potential impacts to minority and low-income populations (including migrant workers or Native 

17 Americans) would mostly consist of socioeconomic and radiological effects; however, radiation

18 doses from continued operations during the license renewal term are expected to continue at 

19 current levels and would remain below regulatory limits. Chapter 5 of this SEIS discusses the 

20 environmental impacts from postulated accidents that might occur during the license renewal 

21 term, which include both design-basis and severe accidents. In both cases, the NRC has 

22 generically determined that impacts associated with design-basis accidents are SMALL

23 because nuclear plants are designed and operated to successfully withstand such accidents, 

24 and the probability-weighted risks associated with severe accidents were also SMALL. 

25 Therefore, based on this information and the analysis of human health and environmental 

26 impacts presented in Chapters 4 and 5 of this SEIS, there would be no disproportionately high 

27 and adverse impacts to minority and low-income populations from the continued operation of 

28 STP during the license renewal term.

29 As part of addressing environmental justice concerns associated with license renewal, the NRC 

30 also assessed the potential radiological risk to special population groups (such as migrant 

31 workers or Native Americans) from exposure to radioactive material received through their 

32 unique consumption and interaction with the environment patterns. These include subsistence 

33 consumption of fish, native vegetation, surface waters, sediments, and local produce; 

34 absorption of contaminants in sediments through the skin; and inhalation of airborne radioactive 

35 material released from the plant during routine operation. This analysis is presented below.

Subsistence Consumption of Fish and Wildlife

40 Section 4-4 of EO 12898 (1994) directs Federal agencies, whenever practical and appropriate, 

41 to collect and analyze information on the consumption patterns of populations that rely 

42 principally on fish or wildlife or both for subsistence and to communicate the risks of these 

43 consumption patterns to the public. In this SEIS, the NRC considered whether there were any 

44 means for minority or low-income populations to be disproportionately affected by examining 

45 impacts to American Indians, Hispanics, migrant workers, and other traditional lifestyle special 

36 . The special pathway receptors analysis is an 

37 important part of the environmental justice analysis because consumption patterns may reflect 

38 the traditional or cultural practices of minority and low-income populations in the area, such as 

39 migrant workers or Native Americans.
Environmental Impacts of Operation

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1 pathway receptors. Special pathways take into account the levels of radiological and 

2 nonradiological contaminants in native vegetation, crops, soils and sediments, groundwater, 

3 surface water, fish, and game animals on or near STP.

4 The following is a summary discussion of the NRC’s evaluation from Section 4.8.2 of the REMP

5 that assesses the potential impacts for subsistence consumption of fish and wildlife near the 

6 STP site.

7 STPNOC has an ongoing, comprehensive REMP to assess the impact of STP operations on the 

8 environment. To assess the impact of nuclear power plant operations, samples are collected 

9 annually from the environment and analyzed for radioactivity. A nuclear power plant effect 

10 would be indicated if the radioactive material detected in a sample was significantly larger than 

11 background levels. Two types of samples are collected. The first type, control samples, is

12 collected from areas that are beyond the measurable influence of the nuclear power plant or any 

13 other nuclear facility. These samples are used as reference data to determine normal 

14 background levels of radiation in the environment. These samples are then compared with the 

15 second type of samples, indicator samples, collected near the nuclear power plant. Indicator 

16 samples are collected from areas where any contribution from the nuclear power plant will be at 

17 its highest concentration. These samples are then used to evaluate the contribution of normal

18 nuclear power plant operations to radiation or radioactivity levels in the environment. An effect 

19 would be indicated if the radioactivity levels detected in an indicator sample was significantly 

20 larger than the control sample or background levels.

21 Samples of environmental media are collected from the aquatic and terrestrial pathways in the 

22 vicinity of STP. The aquatic pathways include surface water, groundwater, drinking water, fish, 

23 crab, shrimp, oyster, and shoreline sediment. The terrestrial pathways include airborne 

24 particulates, food products (i.e., leafy vegetables such as cabbage and various edible greens, 

25 are collected from gardens and farms in the vicinity of STP), beef, poultry, wild animal meat 

26 (i.e., waterfowl, deer, rabbits, and alligator), and broadleaf vegetation. In 2010, analyses 

27 performed on samples of environmental media showed no significant or measurable radiological 

28 impact above background levels from normal STP operations (STPNOC 2011).

Conclusion

4.10

29 . Based on the radiological environmental monitoring data from STP, the NRC finds 

30 that no disproportionately high and adverse human health impacts would be expected in special 

31 pathway receptor populations in the region as a result of subsistence consumption of water, 

32 local food, fish, and wildlife.

34 The staff has not identified new and significant information on environmental issues related to 

35 operation during the renewal term. The staff also determined that information provided during 

36 the public comment period did not identify any new issue that requires site-specific assessment. 

37 The staff reviewed the discussion of environmental impacts associated with operation during the 

38 renewal term in the GElS and has conducted its own independent review, including public 

39 involvement process (e.g., public meetings) to identify issues with new and significant 

40 information.

33 Evaluation of New and Potentially Significant Information

41 New and significant information is information that identifies a significant environmental issue 

42 not covered in the GEIS and codified in Table B-1 of 10 CFR Part 51, Subpart A, Appendix B, or 

43 information that was not considered in the analyses summarized in the GEIS and that leads to 

44 an impact finding that is different from the finding presented in the GEIS and codified in 

45 10 CFR Part 51.
Environmental Impacts of Operation

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1 In accordance with 10 CFR 51.53(c), the ER submitted by the applicant must provide an 

2 analysis of the Category 2 issues in Table B-1 of 10 CFR Part 51, Subpart A, Appendix B. 

3 Additionally, it must discuss actions to mitigate any adverse impacts associated with the 

4 proposed action and environmental impacts of alternatives to the proposed action. In 

5 accordance with 10 CFR 51.53(c)(3), the ER does not need to contain an analysis of any 

6 Category 1 issue unless there is significant new information on a specific issue. 

7 The NRC also has a process for identifying new and significant information. That process is 

8 described in NUREG-1555, Supplement 1, Standard Review Plans for Environmental Reviews 

9 for Nuclear Power Plants, Supplement 1: Operating License Renewal (NRC 1999b). The 

10 search for new information includes: 

11 • review of an applicant’s ER and the process for discovering and evaluating 

12 the significance of new information, 

13 • review of public comments, 

14 • review of environmental quality standards and regulations, 

15 • coordination with Federal, State, and local environmental protection and 

16 resource agencies, and 

17 • review of the technical literature. 

18 New information discovered by the staff is evaluated for significance using the criteria set forth 

19 in the GEIS. For Category 1 issues where new and significant information is identified, 

20 reconsideration of the conclusions for those issues is limited in scope to the assessment of the 

21 relevant new and significant information; the scope of the assessment does not include other 

22 facets of an issue that are not affected by the new information.

4.11

24 The staff considered potential cumulative impacts in the environmental analysis of continued 

25 operation of STP nuclear plant during the 20-year license renewal period. Cumulative impacts 

26 may result when the environmental effects associated with the proposed action are overlaid or 

27 added to temporary or permanent effects associated with other past, present, and reasonably 

28 foreseeable actions. Cumulative impacts can result from individually minor, but collectively 

29 significant, actions taking place over a period of time. It is possible that an impact that may be 

30 SMALL by itself could result in a MODERATE or LARGE cumulative impact when considered in 

31 combination with the impacts of other actions on the affected resource. Likewise, if a resource 

32 is regionally declining or imperiled, even a SMALL individual impact could be important if it 

33 contributes to or accelerates the overall resource decline.

23 Cumulative Impacts

34 For the purposes of this cumulative analysis, past actions are those before the receipt of the 

35 license renewal application. Present actions are those related to the resources at the time of 

36 current operation of the power plant, and future actions are those that are reasonably 

37 foreseeable through the end of plant operation including the period of extended operation. 

38 Therefore, the analysis considers potential impacts through the end of the current license terms 

39 as well as the 20-year renewal license term. The geographic area over which past, present, 

40 and reasonably foreseeable actions would occur is dependent on the type of action considered 

41 and is described below for each resource area.

42 The staff describes the incremental impacts of the proposed action (i.e., STP license renewal) in 

43 Sections 4.1-4.9 of this SEIS. To evaluate cumulative impacts, the incremental impacts of the 
Environmental Impacts of Operation

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1 proposed action are combined with other past, present, and reasonably foreseeable future 

2 actions regardless of what agency (Federal or non-Federal) or person who undertakes such 

3 actions. The staff used the information provided in the ER; responses to requests for additional 

4 information; information from other Federal, State, and local agencies; scoping comments; and 

5 information gathered during the audit at the STP site to identify other past, present, and 

6 reasonably foreseeable actions. To be considered in the cumulative analysis, the staff 

7 determined if the project would occur within the noted geographic areas of interest and within 

8 the period of extended operation, if it was reasonably foreseeable, and if there would be 

9 potential overlapping effect with the proposed project. For past actions, consideration within the 

10 cumulative impacts assessment is resource and project specific. In general, the effects of past 

11 actions are included in the description of the affected environment in Chapter 2, which serves as 

12 the baseline for the cumulative impacts analysis. However, past actions that continue to have 

13 an overlapping effect on a resource potentially affected by the proposed action are considered 

14 in the cumulative analysis.

15 Other actions and projects were identified during this review and considered in the staff’s 

16 independent analysis of the potential cumulative effects. Examples of other actions and 

17 projects that were considered in this analysis include the following:

18 • proposed STP, Units 3 and 4, 

19 • White Stallion Energy Center (WSEC), 

20 • LCRA–San Antonio Water System (SAWS) Project,

21 • Mary Rhodes Pipeline Phase II, and 

22 • Brazos Bend State Park, Mad Island Marsh Preserve, Mad Island Wildlife 

23 Management Area, Big Boggy National Wildlife Refuge, and the Texas Prairie 

24 Wetland Project. 

25 The complete description of each of the projects and actions that were considered are listed in 

26 the discussions of the following sections. 

27 4.11.1 Land Use

28 As discussed in Section 4.1 of this SEIS, onsite land use and powerline right-of-way conditions 

29 are expected to remain unchanged during the license renewal term for STP. Therefore, 

30 cumulative impacts of land use are SMALL. 

31 4.11.2 Air Quality

32 This section addresses the direct and indirect effects of license renewal on air quality resources 

33 when added to the aggregate effects of other past, present, and reasonably foreseeable future 

34 actions. The geographic area considered in the cumulative air quality analysis is the county of 

35 the proposed action because air quality designations for criteria air pollutants are generally 

36 made at the county level. Counties are further grouped together based on a common air 

37 shed—known as an air quality control region (AQCR)—to provide for the attainment and 

38 maintenance of the National Ambient Air Quality Standards (NAAQS). The STP site is located 

39 in Matagorda County, Texas, which is part of the Metropolitan Houston-Galveston Intrastate 

40 AQCR (40 CFR 81.38). Additional counties in this AQCR include Austin, Brazoria, Chambers, 

41 Colorado, Fort Bend, Galveston, Harris, Liberty, Montgomery, Walker, Waller, and Wharton 

42 Counties.
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1 Section 2.2.2 summarizes the air quality designation status for Matagorda County as well as 

2 other counties in the Metropolitan Houston-Galveston Intrastate AQCR. As noted in 

3 Section 2.2.2, EPA regulates six criteria pollutants under the NAAQS. These pollutants are

4 carbon monoxide, lead, nitrogen dioxide, ozone, sulfur dioxide, and particulate matter. 

5 Matagorda County is designated as unclassified or in attainment for all NAAQS criteria 

6 pollutants. All other counties in this AQCR are designated as unclassified or in attainment with 

7 respect to the NAAQS criteria pollutants, except Brazoria County, which is classified 

8 nonattainment/severe relative to the 8-hour ozone standard.

9 Criteria pollutant air emissions from the STP site are presented in Section 2.2.2.1. These 

10 emissions are principally from standby diesel generators and conform to Texas State air 

11 emission requirements in 30 TAC 101.10 (Texas Administrative Code). Continued operations of 

12 the STP site would result in annual air emissions comparable to those noted in Section 2.2.2.1. 

13 Assuming an average annual emission rate of 58.62 tons per year of total emissions from all 

14 sources, an additional 20 years of operation would result in approximately 1,172.4 tons 

15 (1,066.9 metric tons) of total emissions from all sources. There is no planned site refurbishment 

16 associated with license renewal; therefore, there are no additional air emissions beyond those 

17 noted in Section 2.2.2.1 for normal operations.

18 Foreseeable projects that could contribute meaningfully to cumulative impacts to air quality 

19 include the construction and operation of STP, Units 3 and 4, and the construction and 

20 operation of the WSEC, a 1,320 mW coal and petroleum coke plant located about 5 mi (8 km) 

21 northeast of the STP site (MCEDC 2011).

22 In September 2007, STPNOC submitted COL applications to the NRC for two new nuclear units 

23 on the STP site. If approved, STPNOC would construct the new units adjacent to the currently 

24 operating Units 1 and 2. Construction activities would cause some localized temporary 

25 air-quality effects because of emissions and fugitive dust from operation of the earth-moving 

26 and material-handling equipment. Emissions from workers’ vehicles and motorized construction 

27 equipment exhaust would be temporary. NRC assumed that construction crews would use 

28 dust-control practices to control and reduce fugitive dust. STPNOC proposed such activities 

29 during construction of proposed Units 3 and 4 (STPNOC 2010b). Section 111.145 of TCEQ’s 

30 regulations requires dust suppression control during the construction of facilities and parking 

31 lots. Construction activities and their effect on air quality will be similar for the WSEC coal plant. 

32 It is unlikely that construction of the two projects would overlap because WSEC is scheduled to 

33 begin construction in 2012, 2 years earlier than the proposed construction of proposed Units 3 

34 and 4.

35 During operations, two new nuclear plants would have similar air emissions, primarily from 

36 backup diesel generators, to those of existing STP, Units 1 and 2. Because air emissions would 

37 be similar for the new nuclear plants, the NRC expects similar air permitting conditions and 

38 regulatory requirements as that for Units 1 and 2. In STPNOC’s ER for Units 3 and 4, STPNOC 

39 stated that “[a]ir emissions sources would be managed in accordance with Federal, Texas, and 

40 local air quality control laws and regulations.” Likewise, NRC assumes that the WSEC facility 

41 would be operated in accordance with Federal, Texas, and local air quality control laws and 

42 regulations. Effluents from power plants such as the WSEC are typically released through 

43 stacks and with significant vertical velocity. Section 8.3.1 of this SEIS characterizes the impacts 

44 for the emissions from similar plants as being clearly noticeable, but given existing regulatory 

45 regimens, permit requirements, and emissions controls, the coal-fired plant would not 

46 destabilize air quality.
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1 Potential cumulative effects of global climate change (GCC) and increases in average annual 

2 temperatures, higher probabilities of extreme heat events, higher occurrences of extreme 

3 rainfall (intense rainfall or drought), and changes in the wind patterns could affect 

4 concentrations of the air pollutants and their long-range transport because their formation 

5 partially depends on the temperature and humidity and is a result of the interactions between 

6 hourly changes in the physical and dynamic properties of the atmosphere, atmospheric 

7 circulation features, wind, topography, and energy use (IPCC 2010).

8 The NRC staff examined the cumulative effects of the continued operation of STP, Units 1 

9 and 2, the construction and operation of STP, Units 3 and 4, and the construction and operation 

10 of the WSEC coal plant. The cumulative impacts on criteria pollutants from emissions of 

11 effluents from the STP site and the WSEC would be noticeable, principally as a result of the 

12 contribution of WSEC, but not destabilizing. The NRC staff concludes that cumulative impacts 

13 from other past, present, and reasonably foreseeable future actions on air quality resources in 

14 the geographic areas of interest would be MODERATE. The incremental contribution of 

15 impacts on air quality resources associated with STP license renewal would be SMALL, as 

16 described in Section 4.2.

17 4.11.3 Water Resources

18 This section addresses the direct and indirect effects of license renewal on water resources 

19 when added to the aggregate effects of other past, present, and reasonably foreseeable future 

20 actions. As described in Sections 4.3 and 4.4, the incremental impacts on water resources from 

21 continued operations during the proposed license renewal term would be SMALL. This analysis 

22 considers three geographic areas of interest. For the lower Colorado River, the geographic 

23 area of interest is the drainage basin of the Colorado River and Matagorda Bay in Region K. 

24 For the Shallow Chicot Aquifer, which could be affected by seepage and spills, the geographic 

25 area of interest extends from recharge areas in Matagorda County to downgradient discharge 

26 areas along the Colorado River. For the Deep Chicot Aquifer, the geographic area of interest 

27 extends from recharge areas in Wharton County to Matagorda Bay. 

28 The Colorado River and Chicot aquifers are hydraulically connected. As such, this review 

29 focused on the projects and activities that would use groundwater or could affect the Chicot 

30 aquifers beneath the STP site or would withdraw or discharge water to the Colorado River within 

31 their respective geographic areas.

32 4.11.3.1 Cumulative Impacts on Surface Water Resources

33 In addition to continued operation of STP, Units 1 and 2, the NRC staff identified several other 

34 past, present, and foreseeable projects (NRC 2011b). These projects include the proposed 

35 STP, Units 3 and 4, the WSEC, the LCRA–SAWS Project, and the Mary Rhodes Pipeline 

36 Phase II Project, in addition to the existing water use for municipal, irrigation, industrial, and 

37 instream uses. NRC and USACE (2011b) also considered potential effects of GCC on water 

38 supply in Region K, in which STP, Units 1 and 2, is located.

39 The projected average long-term consumptive surface-water use of proposed STP, Units 3 

and 4, would be 37,430 ac-ft/yr (46.2 million m3 40 /yr) at 100 percent load factor (NRC 2011b). 

41 The projected consumptive use for STP, Units 3 and 4, is 2.8 and 2.9 percent of the water 

42 available to Region K in 2010 and 2060, respectively. Because the incremental water use of 

43 proposed STP, Units 3 and 4, is a small percentage of the water available to the region and 

44 would not require additional allocation over the current water right held by STPNOC, the NRC 

45 staff concludes that the incremental impact of water use for STP, Units 3 and 4, on the Colorado 

46 River would be minimal.
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1 Although its future is uncertain because of continuing legal action, a water-sharing project 

2 between the LCRA and the SAWS, involving Regions K and L, could affect water resources in 

3 the region. An off-channel storage reservoir in Wharton County is proposed. The planned 

project would provide 377,000 ac-ft/yr (465 million m3 4 /yr) of water to Regions K and L, and 

Region L would receive 150,000 ac-ft/yr (185 million m3 5 /yr) from Region K starting in the 

6 2020 decade (NRC 2011b). The LCRWPG has considered the effects of the LCRA–SAWS 

7 Project while estimating the water availability in its 2011 Region Water Plan (LCRWPG 2010).

8 The WSEC is a 1,320-MW power plant, proposed to be located in Matagorda County near 

9 Farm-to-Market (FM) Road 2668, 1 mi (1.6 km) south of the Port of Bay City, approximately 5 mi 

10 (8 km) northeast of the STP site. On October 13, 2008, proponents for WSEC applied to LCRA 

for a new firm water supply of 22,000 ac-ft/yr (27 million m3 11 /yr), with the total diversion from the 

Colorado River estimated at 29,750 ac-ft/yr (37 million m3 12 /yr), accounting for delivery losses 

13 (NRC 2011b). The total WSEC withdrawal would be 2.2 and 2.3 percent of the water available 

14 to the region in 2010 and 2060, respectively. Because the incremental water withdrawal for 

15 WSEC is a small percentage of the water available to the region, the NRC staff concludes that 

16 the impact of WSEC withdrawal on the region’s water supply would be minimal.

The City of Corpus Christi has a water right amounting to 35,000 ac-ft/yr (43 million m3 17 /yr) from 

18 the Colorado River (NRC 2011b). Water planning of the City of Corpus Christi indicates that the 

19 city may start to use its currently unused water rights from the Colorado River by 2020 or 

20 sooner, depending on demand (City of Corpus Christi 2011). Although the City of Corpus 

21 Christi does not currently use its water rights from the Colorado River, these rights are 

22 accounted for in Region K water availability planning. To use its water rights from the Colorado 

23 River, the City of Corpus Christi would build Phase II of Mary Rhodes Pipeline from Bay City to 

24 Lake Texana to tie into the existing Phase I of the pipeline that delivers water from Lake Texana 

25 to the city (NRC 2011b). The City of Corpus Christi water right would represent 2.6 and 

26 2.7 percent of the water available to the region in 2010 and 2060, respectively. Because the 

27 incremental water withdrawal by the City of Corpus Christi is a small percentage of the water 

28 available to Region K, the NRC staff concludes that the impact of the City of Corpus Christi 

29 withdrawal on the region’s water supply would be minimal.

30 Freshwater inflow needs for Matagorda Bay represent the only use of lower Colorado River 

31 waters downstream of the STP site (NRC 2011b). The LCRA, TCEQ, Texas Parks and Wildlife 

32 Department, and the TWDB estimated Matagorda Bay freshwater inflow needs (LCRA et 

33 al. 2006). LCRA et al. (2006) estimated a target for freshwater inflow that would optimize 

34 productivity of selected estuarine species and the critical freshwater inflow that would promote 

35 repopulation of finfish and shellfish following a dry period. The average target freshwater inflow 

was established at 118,975 ac-ft/mo (146.7 million m3

/mo) or 1,972 cfs (55 m3 36 /s). The critical 

freshwater inflow was established at 36,000 ac-ft/mo (44 million m3

/mo) or 597 cfs (17 m3 37 /s). 

38 Recommendations made in LRCA et al. (2006) with regard to inflow needs continue to be 

39 reviewed by the TCEQ, and, if formally established, they could make the cited volume of surface 

40 water discharge unavailable for other uses (NRC 2011b).

41 NRC and USACE (NRC 2011b) considered the U.S. Global Change Research Program’s 

42 (USGCRP’s) most recent compilation of the state of knowledge relative to GCC effects 

43 (USGCRP 2009). NRC and USACE reviewed forecasted increases in temperature and 

44 decreases in precipitation for the Colorado River watershed reported by USGCRP (2009) and 

45 determined that GCC could affect water supply in the Colorado River Basin by reducing surface 

46 runoff and increasing evapotranspiration during the period of STP, Units 1 and 2, extended 

47 operations. The USGCRP has identified that the region is likely to experience water conflicts by 

48 2025 because of increasing population and potential endangered species’ needs 
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1 (USGCRP 2009). The NRC and USACE (NRC 2011b) concluded that while the GCC-related 

2 changes may not be insignificant nationally or globally, their impact on STP regional water 

3 resources would not be destabilizing. Thus, the NRC staff concludes that GCC effects would 

4 not substantially add to regional surface water cumulative impacts during the license renewal 

5 term for STP, Units 1 and 2.

6 Historically, the waters of the Colorado River Basin have been extensively used, and the region 

7 has surface water planning, allocation, and development systems in place to manage the use of 

8 its limited surface water resources. The cumulative impact on surface water use in Region K 

9 relative to the unaltered conditions prior to these uses, from past and present diversions and 

10 reasonably foreseeable future projects, would noticeably alter but not destabilize the surface 

11 water resource. Nevertheless, due to the potential impacts associated with water use conflicts 

12 and maintenance of Colorado River flows to Matagorda Bay, the NRC staff concludes that 

13 cumulative impacts on surface water resources during the license renewal term would be 

14 MODERATE. 

15 4.11.3.2 Cumulative Impacts on Groundwater Resources 

16 Water drawn from the Shallow Chicot Aquifer in the vicinity of the STP site is slightly saline, and, 

17 consequently, it is used primarily for livestock watering. Offsite livestock wells are located close 

18 to the STP site boundary, and four are located on leased grazing land within the STP site 

19 (i.e., between the MCR and the Colorado River) (see Section 2.2.5.1). No groundwater is 

20 withdrawn from the Shallow Chicot Aquifer for use by STP, Units 1 and 2. STP operation does 

21 result in seepage from the MCR entering the Upper Shallow Aquifer, and the MCR water carries 

22 with it the constituents contained in plant cooling water (e.g., tritium, TDS) (NRC 2011b; 

23 STPNOC 2010b). Operation of the plant has also resulted in leaks and releases to the Shallow 

24 Aquifer within the protected area (e.g., the TDS line leaks and steam condensate discharge) 

25 (MACTEC 2009). These releases have not substantially affected the groundwater quality within 

26 the STP site, and impacts on groundwater quality off site would be less. Specifically, for the 

27 Shallow Chicot Aquifer, tritium levels remain below the EPA primary DWS, and TDS 

28 concentrations remain within the range defining a slightly saline groundwater. Because of the 

29 reasons presented above, the NRC staff concludes that cumulative impacts on groundwater use 

30 and quality during the license renewal term, related to the Shallow Chicot Aquifer, would be 

31 SMALL. 

32 In contrast, water drawn from the Deep Chicot Aquifer is of higher quality. Aside from the 

33 existing STP-owned groundwater wells completed in the Deep Chicot Aquifer that supply STP, 

34 Units 1 and 2, the closest wells to the STP site completed in the Deep Chicot Aquifer are the 

35 public water supply wells in the communities of Selkirk and Exotic Isle, which are located 

36 adjacent to the STP site eastern boundary (see Section 2.2.5). Wells for these communities are 

37 approximately 1 mi (1.6 km) from the nearest STP production well and 3.75 mi (6 km) from STP, 

38 Units 1 and 2. Review of other existing or planned projects in the surrounding area indicates 

39 groundwater use by Equistar Chemicals LP’s Matagorda facility, the OXEA Corporation Bay City 

40 Plant, and the municipal water supply for Bay City. The shortest distance from this group of 

41 facilities to STP is approximately 5 mi (8 km) (NRC 2011b).

42 Groundwater used at STP, Units 1 and 2, is from the Deep Chicot Aquifer. Public water 

43 supplies and other large-scale industrial users also draw from this aquifer. As noted in 

44 Section 4.4.2.1, there has been a regional drawdown in the Deep Aquifer in the vicinity of the 

45 STP site. By 1980, a regional drawdown of approximately 35 ft (11 m) was attributed to 

46 groundwater development to the north of the STP site (STPNOC 2009a). Proposed STP, 

47 Units 3 and 4, would also use the groundwater from the production wells at the STP site. 
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1 Groundwater use by STP, Units 1 and 2, is 768 gpm (2,910 L/min) for normal operations (see 

2 Section 2.1.7.2). Groundwater use by the proposed STP, Units 3 and 4, is 975 gpm

3 (3,690 L/min) for normal operations. These rates represent 2.4 and 3.1 percent, respectively, of 

4 the annual rate of groundwater use permitted by the CPGCD in Matagorda County during the 

5 2008 to 2010 permit period (NRC 2011b). Based on the best available information, other than 

6 the proposed STP, Units 3 and 4, there are no other foreseeable nearby new projects with a 

7 substantial demand for groundwater. The aquifer drawdown projections from STP well pumping 

8 for selected distances are shown in Table 4–6 and discussed in Section 4.4.2.1. Potential 

9 impacts of drawdown from STP operations on other groundwater users, and from other users’ 

10 pumping on STP, would be minimal because the Deep Chicot Aquifer remains confined, and 

11 changes in pumping lift over the 20-year renewal period would not be substantial.

12 Because of higher groundwater use in the past, subsidence has been an issue in the STP 

13 region. The USGS (Ryder and Ardis 2002) has described subsidence in Matagorda County as 

14 less than 1 ft (0.3 m) since 1900 over most of the region, with somewhat higher subsidence of 

15 1.5 ft (0.46 m) noted in western Matagorda County. STPNOC has observed a subsidence rate 

16 of less than 0.1 in. (0.25 cm) to about 0.2 in. (0.50 cm) per year during construction and through 

17 STP, Units 1 and 2, operations in 1993 (STPNOC 2008b). The updated final safety analysis 

18 report (UFSAR) for STP, Units 1 and 2, projected regional subsidence from 1973 through 2020 

19 to be between 2.5 and 3 ft (0.76 and 0.9 m) based on a projected regional groundwater decline

20 of 87 ft (26.5 m) and subsidence coefficients derived from regional observations

21 (STPNOC 2009c). To minimize the potential for subsidence, STPNOC spaced its main 

22 production wells (i.e., wells 5, 6, and 7) over 5,000 ft (1,520 m) apart and distributes the

23 pumping rates among them. All groundwater users in Matagorda County operate their wells 

24 under the rules of the CPGCD (2009). The purpose of the CPGCD is to provide for conserving, 

25 preserving, protecting, and recharging the groundwater to control subsidence and prevent the 

26 waste and pollution of the groundwater resource. Groundwater use under the rules of the 

27 CPGCD minimizes the potential for excessive drawdown, saltwater intrusion, or land 

28 subsidence impacts to arise and affect neighboring groundwater users (CPGCD 2009). Current 

29 observations of drawdown are consistent with the drawdown projected in the UFSAR for STP, 

30 Units 1 and 2, and subsidence projections are consistent with observations. These potential 

31 impacts are greatest on site where they are monitored. As noted in Section 4.3.2.1, drawdown 

32 at STP production wells is currently in equilibrium with the surrounding groundwater aquifer, and 

33 continued operation of STP wells for an additional 20 years beyond the current license would 

34 increase drawdown by less than 1 ft (0.3 m). Additional subsidence resulting from this change 

35 in drawdown during the license renewal term would be minimal.

36 Operation of STP, Units 1 and 2, does not adversely affect groundwater quality in the Deep 

37 Chicot Aquifer because of the low-conductivity layer between 100 and 150 ft (30 and 46 m) thick 

38 that separates and isolates the Shallow Chicot Aquifer from the Deep Chicot Aquifer. Similarly, 

39 because of the hydraulic isolation of the Deep Chicot Aquifer from the Shallow Chicot Aquifer 

40 and any releases at the land surface, other nearby groundwater users are also not adversely 

41 affecting groundwater quality in the Deep Chicot Aquifer. Groundwater drawdown at the STP 

42 production wells is great enough to reverse the regional gradient and draw groundwater in the 

43 Deep Chicot Aquifer from beneath the STP site into the production wells. Thus, if any releases 

44 from the plant were to move from the Shallow to the Deep Chicot Aquifer, the contamination 

45 would likely be drawn to and intercepted by STP groundwater production wells (NRC 2011b).

46 With regard to the Deep Chicot Aquifer, because of the reasons presented above, the NRC staff 

47 concludes that cumulative impacts on groundwater use and quality during the license renewal 

48 term would be SMALL.
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1 4.11.4 Aquatic Resources

2 This section addresses the direct and indirect effects of license renewal on aquatic resources 

3 when added to the aggregate effects of other past, present, and reasonably foreseeable future 

4 actions. The geographic area considered in this analysis includes the STP site and the portion 

5 of the lower Colorado River basin within influence of STP operations, including Matagorda Bay.

6 The benchmark for assessing cumulative impacts on aquatic resources takes into account the 

7 preoperational environment, as recommended by EPA (1999) for its review of NEPA 

8 documents:

9 Designating existing environmental conditions as a benchmark may focus the 

10 environmental impact assessment too narrowly, overlooking cumulative impacts 

11 of past and present actions or limiting assessment to the proposed action and 

12 future actions. For example, if the current environmental condition were to serve 

13 as the condition for assessing the impacts of relicensing a dam, the analysis 

14 would only identify the marginal environmental changes between the continued 

15 operation of the dam and the existing degraded state of the environment. In this 

16 hypothetical case, the affected environment has been seriously degraded for 

17 more than 50 years with accompanying declines in flows, reductions in fish 

18 stocks, habitat loss, and disruption of hydrologic functions. If the assessment 

19 took into account the full extent of continued impacts, the significance of the 

20 continued operation would more accurately express the state of the environment 

21 and thereby better predict the consequences of relicensing the dam.

22 Sections 2.2.5 and 2.2.7 of this SEIS present an overview of the history and factors that led to 

23 the current condition of the aquatic features on the STP site, the Colorado River, and Matagorda 

24 Bay. Since the 1920s, development and redirection of the lower Colorado River has affected 

25 the water quality, water chemistry, and aquatic resources. These alterations have increased the 

26 freshwater input to Matagorda Bay and marine and estuarine inputs to the lower Colorado River, 

27 resulting in a change in salinity. Anthropogenic activities has decreased available habitat for 

28 some species and increased available habitat for others. For example, construction and 

29 development projects have reduced the area available for aquatic organisms to navigate 

30 through the Colorado River and Matagorda Bay due to erosion, habitat modification, and habitat 

31 fragmentation. Overall, species richness and diversity have increased in the lower Colorado

32 River near STP (from the GIWW to navigation mile marker 8) based on surveys in 2007 to 2008 

33 compared to similar surveys in 1983 to 1984 (ENSR 2008b; NRC 1986, 2011b; 

34 STPNOC 2010b). The change in the aquatic community could be due to differences in study 

35 methods (e.g., differences in sampling protocol over time), environmental conditions 

36 (e.g., variance in weather conditions during the two sampling efforts), or from human activities 

37 (e.g., the river diversion projects that has increased the marine and estuarine flow into the lower 

38 Colorado River).

39 Many natural and anthropogenic activities can influence the current and future aquatic biota in 

40 the area surrounding STP. Potential biological stressors include continued entrainment, 

41 impingement, and potential heat shock from STP, Units 1 and 2 (if the license renewal is 

42 granted), as described in Section 4.5, construction and operation of STP, Units 3 and 4, other 

43 water use projects, urbanization, fishing, and GCC, as described below.

44 Construction and Operations of STP, Units 3 and 4. In 2007, STPNOC submitted an application 

45 to the NRC to construct and operate two additional nuclear reactors on the STP site, referred to 

46 in this SEIS as STP, Units 3 and 4. In 2011, NRC published its final EIS evaluating the 

47 environmental impacts of the proposed construction and operations of Units 3 and 4 

48 (NRC 2011b). This project would have overlapping impacts with the continued operations of 
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1 Units 1 and 2. For example, all four units would draw water from the MCR, which need to be 

2 filled higher than current levels (STPNOC 2010c). STPNOC would draw the additional makeup 

3 water from the Colorado River through the RMPF. Species impinged and entrained would be 

4 similar to those impinged and entrained during operations of Units 1 and 2. Past impingement 

5 and entrainment studies and NRC evaluations of such studies concluded that impacts to the 

6 important species would be insignificant and minor, primarily because the density of organisms 

7 in the vicinity is rather low and the species are ubiquitous in the region (McAden 1984, 1985; 

8 NRC 1986, 2011b). Additionally, the design and operation of the RMPF minimize impacts on 

9 aquatic biota, as described in Section 4.5.2. Therefore, impacts from operation of the RMPF 

10 (impingement, entrainment, and entrapment) for four units are unlikely to destabilize aquatic 

11 resources in the lower Colorado River.

12 Operation of the four units would also affect aquatic resources in the MCR. Higher intake levels 

13 to provide cooling water for four units would increase impingement and entrainment at the 

14 CWISs in the MCR. The two discharges from the four units would increase the water 

15 temperature in the MCR. Aquatic organisms in the MCR would either avoid or acclimate to the 

16 new conditions. Because the aquatic community in the MCR is isolated from the onsite water

17 bodies and the Colorado River, these impacts would not noticeably alter the aquatic resources 

18 within the geographic area of interest.

19 Operation of two additional units would increase the frequency and duration of discharges from 

20 the MCR into the Colorado River. STPNOC would manage discharges, as needed, based on 

21 water quality in the MCR and TPDES permit conditions (STPNOC 2010b). Chemical releases 

22 from discharging into the Colorado River are expected to be below the criteria for protection of 

23 aquatic life (TCEQ 2005). NRC (2011b) determined that under certain conditions, such as poor 

24 river water quality, the size and configuration of the thermal plume could impede passage of the 

25 aquatic organisms in the Colorado River, including species that are of commercial and 

26 recreational importance and species that are Federally managed and have designated essential 

27 fish habitat. NRC (2011b) concluded that the foraging behavior and high fecundity of such 

28 aquatic organisms suggest that the effects from the thermal plume would not noticeably alter or 

29 destabilize the populations or aquatic community in the lower Colorado River. 

30 NRC (2011b) concluded that the impacts to aquatic resources from other construction and 

31 operational activities of all four units would not noticeably alter or destabilize aquatic resources. 

32 These impacts include additional seepage from the MCR that could influence flow to Little 

33 Robbins Slough and wetlands, increased non-permeable surfaces (e.g., parking lots and 

34 buildings) that would change the flow of stormwater into the drainages on site, maintenance 

35 dredging in the Colorado River, shoreline restoration activities along the Colorado River, and 

36 disturbances from vessel traffic to marine mammals (NRC 2011b).

Other Water Use Projects

40 The LCRA–SAWS Project is projected to generate 150,000 ac-ft of new water supplies by 2060 

41 through conjunctive use of groundwater from the Gulf Coast Aquifer and surface water supplies 

42 from the Colorado River (TWDB 2006). LCRA–SAWS (2009) will evaluate impacts to aquatic 

43 habitat in the Colorado River with and without the proposed project. WSEC, a proposed 

44 coal-fired generating plant, would withdraw approximately 22,000 ac-ft per year of water from 

45 the lower Colorado River (WSEC 2011). LCRA included water use from WSEC growth in its 

46 water supply resource plan for Region K, Matagorda County. Other sources of water use 

47 included in water supply estimates include increases in municipal use due to population, 

37 . Future projects near STP that would withdraw or redirect significant 

38 quantities of the Colorado River include the proposed LCRA–SAWS Project, WSEC, and 

39 municipal use (TWDB 2006; WSEC 2011).
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1 manufacturing, mining, irrigation, transfer of water via the proposed Mary Rhodes Pipeline II, 

2 and other categories (TWBD 2006). From 2010 to 2040, the plan estimates an annual increase 

3 of 12 percent without the WSEC Project and 80 percent with the WSEC Project (LCRA 2008).

4 These projects have the potential to change the freshwater contribution in the river within the 

5 vicinity of STP by redirecting the flow or by withdrawing a significant amount of freshwater. 

6 Changes in flow of saltwater into the river could change the habitat (or salinity) for many 

7 species. In response, estuarine-marine species would likely become more abundant if the 

8 salinity increases whereas freshwater species would likely become more abundant if the salinity 

9 decreases. The Colorado River diversion project, which increased the flow between the 

10 Colorado River and Matagorda Bay, resulting in an increase in salinity near the STP site, likely 

11 influenced the shift in aquatic communities near STP towards estuarine-marine species 

12 (ENSR 2008b; NRC 1975, 1986, 2011b).

Urbanization and Development

20 Proposed future power generation facilities to support increased energy usage, including WSEC 

21 and the Victoria County Station, may require the development of new transmission systems in 

22 the geographic area of interest. The WSEC may be required to add additional transmission 

23 capabilities within the vicinity for its power transmission, but that information is currently not 

24 available to evaluate (WSEC 2011). If WSEC or Victoria County Station build new transmission 

25 corridors, they would likely have a minor effect on aquatic species assuming the owners 

26 consider aquatic resource when routing transmission lines and employ best management 

27 practices (BMPs) during construction and maintenance activities.

13 . Residential or industrial development in the vicinity of STP site 

14 can affect aquatic resources. Increased urbanization and population growth, while projected to 

15 be low in comparison to other locations in Texas (NRC 2011b), would still lead to increased 

16 development along the shores of the Colorado River that can contribute to cumulative impacts 

17 in the lower Colorado River basin through habitat loss and nonpoint source pollution. Future 

18 activities could lead to increased water needs, nonpoint and point source water pollution, vessel 

19 traffic on the waterways, and maintenance dredging.

28 STPNOC would use existing transmission corridors to support power transmission from 

29 proposed Units 3 and 4 and during the period of extended operations for Units 1 and 2. 

30 STPNOC (2010b, 2010c) would employ vegetation maintenance and control along existing and 

31 future corridors, which would not be expected to increase and contribute to cumulative effects 

32 (NRC 2011b).

33 Fishing. Commercial and recreational fishing in the Colorado River and Matagorda Bay would 

34 likely continue to increase in the future. The region is recognized for recreational fishing of 

35 many species, and fishing would likely increase with increased urbanization in the vicinity. 

36 Matagorda Bay is one of the recognized regions in Texas for commercial fishing, primarily 

37 associated with the shrimp industry (TPWD 2002), although these fisheries are not significant 

38 contributors to employment in the region (NRC 2011b). In efforts to improve the fisheries in the 

39 area, TPWD has designated the “most eastern half of the eastern arm of Matagorda Bay” as a 

40 finfish and shellfish nursery, closing the area to commercial fishing and commercial harvesting 

41 of oysters (LCRA et al. 2006). A freshwater inflow needs study for Matagorda Bay has identified 

42 several alternatives associated with water management strategies designed to improve 

43 commercial fishing opportunities (LCRA et al. 2006). If management strategies do not improve 

44 sustainability of fisheries, increased fishing pressures could result in overall decreased 

45 biological productivity for the Colorado River and Matagorda Bay.

46 Climate Change. In addition to direct anthropogenic activities, GCC could impose additional 

47 stressors on aquatic communities. The presence of natural environmental stressors (e.g., short- 
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1 or long-term changes in precipitation or temperature) would contribute to the cumulative 

2 environmental impacts to the Colorado River and Matagorda Bay. GCC could lead to 

3 decreased precipitation, increased sea levels, varying freshwater inflow, increased 

4 temperatures, increased storm surges, greater intensity of coastal storms, and increased 

5 nonpoint source pollution from runoff during these storms (GCRP 2009; Montagna et al. 1995; 

6 Nielsen-Gammon 1995). Such changes could directly affect habitat for aquatic communities by 

7 altering the flow of freshwater, water quality, salinity, and dissolved oxygen levels. Habitat 

8 alterations could result in changes to community structure, species abundance, and species 

9 diversity. These kinds of changes occurred in the vicinity of STP with the diversion of the 

10 Colorado River into the Gulf and Matagorda Bay since the 1920s (NRC 2011b).

11 GCC could also slow efforts to restore nursery habitats in Matagorda Bay. The Colorado River 

12 diversion project increased the flow of freshwater into the bay in an effort to improve habitat for 

13 wetlands, oyster reefs, and other nursery grounds (USACE 2009). However, LCRA et al. (2006) 

14 indicated slower than expected results and showed that more freshwater inflow into the bay is 

15 needed to increase biological productivity in the bay. The effects of rising sea level, which 

16 would increase salinity in the bay, would likely be counterproductive to the current efforts to 

17 increase freshwater flows into the Bay. Changes in water quality in Matagorda Bay and the 

18 lower Colorado River could create areas that are hypoxic (low in dissolved oxygen) and lead to 

19 further stress on aquatic communities (Montagna et al. 1995). These stressors would result in 

20 shifts in species ranges, habitats, and migratory behaviors and also alter ecosystem processes 

21 (GCRP 2009).

Conclusion

35 4.11.5 Terrestrial Resources

22 . Past, present and reasonably foreseeable future activities exist in the geographic 

23 area of interest that could contribute to cumulative effects to aquatic ecological resources. 

24 Future development of industries that compete for water in the Colorado River, such as WSEC, 

25 as well as management of water budgets across the State of Texas through diversion projects 

26 like the LCRA–SAWS Project and the Mary Rhodes Pipeline Phase II Project, would likely affect 

27 aquatic resources in the lower Colorado River. Such actions in combination with other direct 

28 and indirect anthropogenic and natural environmental stressors, including GCC, would 

29 cumulatively lead to effects on the aquatic communities that would noticeably alter important 

30 attributes such as species range, habitat availability, ecosystem processes, migratory corridors 

31 and behavior, species diversity, and species abundance. The NRC staff concludes that 

32 cumulative impacts from past, present, and reasonably foreseeable actions to aquatic resources 

33 in the geographic area of interest would be MODERATE. The incremental impact from 

34 continued operations of Units 1 and 2 during the period of extended operation would be SMALL.

Historic Conditions

45 The Texas Gulf coasts historically contained abundant and diverse wetlands. Approximately 

46 30 percent of the coastal prairies along the Texas Gulf coasts were once wetlands 

47 (TPWD 2010). Human activities, including landscape alteration for agricultural, industrial, or 

36 . Section 2.6 discusses the ecoregion in which the STP site lies—the 

37 Western Gulf Coastal Plain—which is dominated by tallgrass and shortgrass prairie. 

38 Historically, these prairies covered about 6.5 million ac (2.6 million ha) within Texas. During the 

39 past century, urban and industrial development and agricultural expansions have fragmented 

40 the natural habitat. In the late 1800s, ranchers introduced large numbers of cattle to the region. 

41 Livestock grazing continues to be a major land use, but the majority of land has been altered for 

42 cultivation of rice, sugarcane, forage, and grain. By the 1980s, Diamond and Smeins (1984) 

43 estimated that less than one percent of Texas’s native coastal prairie grasslands remained in a 

44 relatively pristine state.
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1 urban uses, continue to significantly threaten remaining wetland habitats (TPWD 2005). In 

2 addition, decreased precipitation, sea-level rise, more frequent high-intensity storm surges, and 

3 increased temperatures resulting from GCC have contributed to wetland losses (GCRP 2009). 

4 Nonetheless, rice fields, prairie wetlands, and coastal marshes continue to provide important 

5 habitat for waterfowl and many other wildlife species. TPWD (2005) identified the Gulf coasts

6 and associated grassland prairies, wetlands, marshes, and agriculture as one of the most 

7 important wintering areas for North America’s waterfowl populations.

8 On the immediate site, STPNOC cleared land for, built, and filled the 7,000-ac (2,800-ha) MCR 

9 and cleared an additional 300 ac (120 ha) for the facility’s buildings, parking lots, roads, and 

10 other infrastructure. 

11 In the region surrounding the STP site, construction of many industrial facilities and wastewater 

12 treatment plants have resulted in the loss of terrestrial habitat. These facilities include:

13 • the Formosa Plastics Corporation plant,

14 • the Texas Liquid Fertilizer Company,

15 • the Alcoa aluminum plant,

16 • the Equistar Chemical LP’s Matagorda facility, and

17 • the OXEA Corporation’s chemical plant.

Other Projects

20 Chemicals Inc. has a specialty chemical plant near STP. The plant’s 107.5-ac (44-ha) site is 

21 located about 5 mi (8 km) south of Bay City (Chemicals Inc. 2011). 

18 . Many projects near the STP site could affect the terrestrial environment in the 

19 future. These projects are discussed in this section.

22 About 5 mi (8 km) northeast of the STP site, a 1,200-ac (490-ha) tract of land is the site for the 

23 WSEC, a 1,320-net-mW coal and petroleum coke plant (MCEDC 2011). The TCEQ granted the 

24 project its air quality permit in September 2010. The status of the facility’s wastewater permit is 

25 uncertain. Coal-fired plants are a major source of air pollution in the U.S. because they release 

26 sulfur dioxide, nitrogen oxides, mercury, carbon dioxide, and particulates. Nitrous oxides and 

27 sulfur dioxides combine with water to form acid rain, which can lead to erosion and changes in 

28 soil pH levels. Mercury deposits onto soil and surface water, which may then be taken up by 

29 terrestrial and aquatic plant or animal species and poses the risk of bioaccumulation.

30 In September 2007, STPNOC submitted COL applications to the NRC for two new nuclear units 

31 on the STP site. If approved, STPNOC would construct the new units adjacent to the currently 

32 operating Units 1 and 2. As a result, about 540 ac (220 ha) would be disturbed. Of this, the 

33 new reactors, the associated buildings and infrastructure, and a new heavy haul road would 

34 occupy 300 ac (120 ha), and the remaining 240 ac (100 ha) would only be temporarily disturbed 

35 for temporary buildings, construction equipment storage, and material laydown (NRC 2011b). 

36 The majority of land that would be disturbed is currently maintained or mowed grasslands, 

37 shrub-scrub habitat, or used for existing industrial activities. The new units would require 

38 additional transmission lines to transfer power to the regional electric grid. However, STPNOC 

39 would not create any new or expand any existing transmission line corridors (NRC 2011b). In 

40 the NRC’s EIS regarding the proposed new STP units, the NRC (2011b) concluded that impacts 

41 to the terrestrial environment would be SMALL for this proposed action.

42 Development of the proposed Mary Rhodes Pipeline Phase II Project would likely also 

43 contribute to regional habitat loss and fragmentation. Potential cumulative impacts resulting 

44 from construction and operation of the proposed water transport line would be similar to those 
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1 impacts from constructing and maintaining new transmission line corridors and include habitat 

2 fragmentation, creation of early successional habitat, and displacement of certain wildlife 

3 species.

4 For projects listed above, construction and operation would impact wildlife by increasing noise 

5 and traffic, which could alter behavior or cause a shift in habitat use in undisturbed land 

6 bordering construction areas. Birds in the immediate area would be more likely collide with tall 

7 structures and construction equipment. However, construction impacts would be short-term and 

8 relatively minor. Hence, the impacts would not destabilize the environment.

9 Urbanization and Habitat Fragmentation. As the region surrounding the STP site becomes 

10 more developed, habitat fragmentation will increase. Species that require larger ranges, 

11 especially predators, will likely suffer reductions in their populations. In contrast, herbivores will 

12 experience less predation pressure, and their populations are likely to increase. Edge species 

13 will likely benefit from the fragmentation, while species that require interior forest or swamp 

14 habitat will likely suffer. The transmission line corridors established for STP transmission lines 

15 represent habitat fragmentation, though many of these corridors pass through cultivated land 

16 that has already been converted from its native habitat or shrub-scrub habitat, which was 

17 minimally altered during transmission line construction. Habitat fragmentation of surrounding 

18 areas may increase the value of the network of wetlands within the Texas Prairie Wetlands 

19 Project—110 ac of which is set aside on the STP site—because this land will not experience 

20 fragmentation or other human-induced impacts.

Parks and Wildlife Preserves

23 • Brazos Bend State Park, 

21 . The FWS and State have set many lands in the STP region aside 

22 as parks, preserves, or management areas. These include:

24 • Mad Island Marsh Preserve, 

25 • Mad Island Wildlife Management Area,

26 • Big Boggy National Wildlife Refuge, and 

27 • the Texas Prairie Wetland Project, for which 110 ac (45 ha) on the STP site is 

28 set aside.

29 Section 2.2.6 of this SEIS describes these parks and preserves in more detail. These areas will 

30 continue to provide valuable habitat to native wildlife, migratory birds, and native prairie and 

31 marsh vegetation. Both the National Wildlife Refuge Network and the Texas Prairie Wetland 

32 Project are ongoing efforts. In the future, FWS and Ducks Unlimited will continue to acquire 

33 lands for these projects.

Conclusion

41 4.11.6 Human Health

34 . The NRC staff examined the cumulative effects of the construction of STP, 

35 neighboring energy projects, continued urbanization and habitat fragmentation, and nearby 

36 parks and wildlife preserves. The NRC staff concludes that the minimal terrestrial impacts on 

37 the continued STP operations would not contribute to the overall decline in the condition of 

38 terrestrial resources. The NRC staff believes that the cumulative impacts of other and future 

39 actions during the term of license renewal on terrestrial habitat and associated species, when 

40 added to past, present, and reasonably foreseeable future actions, would be MODERATE.

42 Radiological Impacts. The radiological dose limits for protection of the public and workers have 

43 been developed by the NRC and EPA to address the cumulative impact of acute and long-term 
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1 exposure to radiation and radioactive material. These dose limits are codified in 

2 10 CFR Part 20 and 40 CFR Part 190. For the purpose of this analysis, the area within a 50-mi 

3 (80.4-km) radius of STP was included. The REMP conducted by STPNOC in the vicinity of the 

4 STP site measures radiation and radioactive materials from all sources (i.e., hospitals and other 

5 licensed users of radioactive material); therefore, the monitoring program measures cumulative 

6 radiological impacts. Within the 50-mi (80-km) radius of the STP site, there are currently no 

7 other nuclear power reactors or uranium fuel cycle facilities.

8 Radioactive effluent and environmental monitoring data for the 5-year period from 2006 to 2010 

9 were reviewed as part of the cumulative impacts assessment. In Section 4.8.1 of this SEIS, the 

10 NRC staff concluded that impacts of radiation exposure to the public and workers (occupational) 

11 from operation of STP during the renewal term are SMALL. The NRC and the State of Texas 

12 would regulate any future actions in the vicinity of the STP site that could contribute to 

13 cumulative radiological impacts.

14 As stated in its ER, the applicant stores its spent nuclear fuel in its spent fuel pool. The 

15 applicant estimates that there is adequate capacity in its spent fuel pool to store spent fuel until 

16 2025. For reactor operations past that date, STPNOC plans to install a dry fuel storage system 

17 at the STP site for the storage of its spent fuel. The installation and monitoring of this facility will 

18 be governed by NRC requirements in 10 CFR Part 72, “Licensing Requirements for the 

19 Independent Storage of Spent Nuclear Fuel, High-Level Radioactive Waste, and 

20 Reactor-Related Greater Than Class C Waste.” Radiation from this projected storage facility as 

21 well as from the operation of STP, Units 1 and 2, are required to be within the radiation dose 

22 limits in 10 CFR Part 20, 40 CFR Part 190, and 10 CFR Part 72. The NRC performs periodic 

23 inspections of every licensed dry fuel storage facility to verify its compliance with all licensing 

24 and regulatory requirements. Currently, the applicant has not submitted an application to the 

25 NRC for the dry fuel storage system, so no further information is available.

26 In September 2007, STPNOC applied to the NRC for a COL pursuant to the requirements of 

27 10 CFR Part 52 for the construction and operation of two additional reactors at the STP site. 

28 STPNOC submitted information on the site and surrounding area to NRC in its application for 

29 the COL. The NRC reviewed the COL application and issued the final EIS (NRC 2011b), which 

30 analyzed the impacts on the surrounding communities and natural resources to determine if the 

31 STP site is suitable to support two additional reactor units (proposed Units 3 and 4). The NRC 

32 also evaluated the cumulative impacts of the operation of four reactor units and considered the 

33 possible life extension of STP, Units 1 and 2, for 20 years. In the final EIS, the NRC staff 

34 concludes that cumulative radiological impacts would be SMALL. 

35 In addition, pursuant to 10 CFR Part 20 and 40 CFR Part 190, the cumulative radiological 

36 impacts from STP, Units 1 and 2, the possible projected dry fuel storage system, and two 

37 additional reactor units are required to meet the acceptable radiation dose limits (protecting 

38 human health) specified in these regulations. EPA regulation (40 CFR 190) limits the total dose 

39 to an offsite individual near STP from “all uranium fuel cycle facilities and all pathways,” located 

40 at STP. Furthermore, the STP REMP would monitor the buildup of radioactivity in the 

41 environment to effectively ensure that the levels remain acceptable. Based on this information, 

42 the staff concludes that cumulative radiological impacts would be SMALL.

43 Electromagnetic Fields Impacts. For electromagnetic fields impacts on human health, the staff 

44 determined that not all of the STP transmission lines are operating within design specifications 

45 and meet current NESC criteria. In Section 4.8.4, the NRC staff determined that the potential 

46 impacts from STP transmission lines were SMALL to MODERATE. However, STP addressed 

47 the issue of acute shock by providing the staff with potential actions it is considering to mitigate 
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1 the impacts. Therefore, the staff concludes that the transmission lines are not expected to 

2 significantly affect the overall potential for electric shock from induced currents within the 

3 analyzed area of interest. 

4 With respect to the effects of chronic exposure to ELF-EMF, as discussed in Section 4.8.5, the 

5 GEIS finding of “uncertain” is appropriate to STP. 

6 For the reasons listed above, the staff concludes that the cumulative impacts of continued 

7 operation of the STP transmission lines and other transmission lines in the affected area would 

8 be SMALL to MODERATE.

Microorganisms Impacts

21 4.11.7 Socioeconomics

9 . In the environmental review for the proposed Units 3 and 4, the NRC 

10 staff determined that other projects (e.g., the Mary Rhodes Pipeline Phase II Project) would use 

11 or divert river water upstream of STP. These projects, depending on the magnitude and without 

12 mitigation measures, could reduce freshwater river flow and increase the ambient river water 

13 temperature (Neuces River Authority 2001; TWDB 2006b; WSEC 2009). Therefore, this 

14 cumulative effect on Colorado River conditions could be favorable for an increased presence of 

15 thermophilic microorganisms and, subsequently, increase the risk of public exposure to potential 

16 harmful microorganisms (thermophilic). However, based on past data on waterborne diseases 

17 from recreational water activities in Texas and the discharging limits on STP, cumulative 

18 impacts to human health due to exposure to microorganisms in the Colorado River would likely 

19 be minimal (CDC 2009; TDSHS 2010). Hence, the staff concludes that cumulative impacts to 

20 human health due to exposure to microorganisms in the Colorado River would be SMALL. 

22 This section addresses socioeconomic factors that have the potential to be directly or indirectly 

23 affected by changes in operations at STP in addition to the aggregate effects of other past, 

24 present, and reasonably foreseeable future actions. The primary geographic area of interest 

25 considered in this cumulative analysis is Brazoria and Matagorda Counties, where 

26 approximately 84 percent of STP employees reside (see Table 2–12). This is where the 

27 economy, tax base, and infrastructure would most likely be affected since STP workers and 

28 their families reside, spend their income, and use their benefits within these counties.

29 As discussed in Section 4.9 of this SEIS, continued operation of STP during the license renewal

30 term would have no impact on socioeconomic conditions in the region beyond those already 

31 experienced. Since STPNOC has no plans to hire additional workers during the license renewal 

32 term, overall expenditures and employment levels at STP would remain relatively constant with 

33 no additional demand for permanent housing and public services. In addition, since 

34 employment levels and tax payments would not change, there would be no population or tax 

35 revenue-related land use impacts. Based on this information and other information presented in 

36 Chapter 4 of this SEIS, there would be no additional contributory effect on socioeconomic 

37 conditions in the future from the continued operation of STP during the license renewal term 

38 beyond what is currently being experienced. 

39 Environmental Justice. The environmental justice cumulative impact analysis assesses the 

40 potential for disproportionately high and adverse human health and environmental effects on 

41 minority and low-income populations that could result from past, present, and reasonably 

42 foreseeable future actions including STP operations during the renewal term. Adverse health 

43 effects are measured in terms of the risk and rate of fatal or nonfatal adverse impacts on human 

44 health. Disproportionately high and adverse human health effects occur when the risk or rate of 

45 exposure to an environmental hazard for a minority or low-income population is significant and 

46 exceeds the risk or exposure rate for the general population or for another appropriate 
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1 comparison group. Disproportionately high environmental effects refer to impacts or risk of 

2 impact on the natural or physical environment in a minority or low-income community that are 

3 significant and appreciably exceed the environmental impact on the larger community. Such 

4 effects may include biological, cultural, economic, or social impacts. Some of these potential 

5 effects have been identified in resource areas presented in Chapter 4 of this SEIS. Minority and 

6 low-income populations are subsets of the general public residing in the area, and all would be 

7 exposed to the same hazards generated from STP operations. 

8 Based on the information discussed in this section, and the analysis of human health and 

9 environmental impacts presented in Chapters 4 and 5, it is unlikely there would be any 

10 disproportionately high and adverse contributory effect on minority and low-income populations 

11 from the continued operation of STP and other reasonably foreseeable future actions during the 

12 license renewal term.

13 4.11.8 Historic and Archaeological Resources

14 This section addresses the direct and indirect effects of license renewal on historic and cultural 

15 resources when added to the aggregate effects of other past, present, and reasonably 

16 foreseeable future actions. The geographic area considered in this analysis is the APE 

17 associated with the proposed undertaking, as described in Section 2.2.9. 

18 Before construction of STP, the area was largely undisturbed and contained archaeological 

19 sites. In the early 1970s, the Texas Archaeological Survey conducted cultural resources 

20 investigations of the STP site and surrounding area. The investigations included a literature 

21 review, a pedestrian survey, and limited subsurface testing (NRC 2011b; 

22 STPNOC 2010b, 2010c). The construction of STP was completed in the 1980s, and much of 

23 the site had been heavily disturbed by construction activities including the construction of the 

24 MCR. Section 2.2.10 presents an overview of the existing historic and archaeological resources 

25 located on the STP site. As described in Section 4.9.6, no cultural resources would be affected 

26 by relicensing activities associated with the STP site. 

27 Past land development has resulted in impacts on, and the loss of cultural resources near and 

28 at, the STP site. The impacts from other past, present, and reasonably foreseeable projects 

29 were reviewed to analyze overlapping impacts that might affect cultural resources. Direct 

30 impacts would occur if archaeological sites in the APE are physically removed or disturbed. The 

31 following projects are located within the geographic area considered for cumulative impacts:

32 • construction and operation of STP, Units 3 and 4, 

33 • transmission lines, and

34 • future urbanization.

35 Construction and operation of STP, Units 3 and 4, transmission lines, and future urbanization 

36 have the potential to result in impacts on cultural resources through inadvertent discovery during 

37 ground-disturbing activities. However, based on the best available information, there are no 

38 known historic or archaeological resources on the STP site. In addition, STPNOC has 

39 environmental compliance procedures in place for cultural resource protection and inadvertent 

40 discovery and has stated the construction and operation activities would not affect the 

41 unrecorded gravesite on the STP site (STPNOC 2011g). Future urbanization near STP would 

42 be required to comply with applicable State and Federal laws regarding protection of cultural 

43 and archaeological resources, and any impacts would be mitigated accordingly.
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1 Based on this information, the NRC staff finds that the continued operation of STP during the 

2 license renewal term would not incrementally contribute to cumulative impacts on historic and 

3 archaeological resources within STP and in the surrounding area. Therefore, the cumulative 

4 impacts on historic and archaeological resources during the license renewal term would be 

5 SMALL.

6 4.11.9 Summary of Cumulative Impacts

7 The staff considered the potential impacts resulting from the operation of STP during the period 

8 of extended operation and other past, present, and reasonably foreseeable future actions near 

9 STP. The preliminary determination is that the potential cumulative impacts would range from 

10 SMALL to MODERATE, depending on the resource. Table 4–17 summarizes the cumulative 

11 impacts on resources areas.

12 Table 4–17. Summary of Cumulative Impacts on Resource Areas

Resource Area Cumulative Impact

Air quality

The NRC staff examined the cumulative effects of the continued operation of 

STP, Units 1 and 2, the construction and operation of STP, Units 3 and 4, and the 

construction and operation of the nearby WSEC coal plant. The cumulative 

impacts on criteria pollutants from emissions of effluents from the STP site and 

the WSEC would be noticeable (but not destabilizing), principally as a result of 

the contribution of WSEC. In addition, cumulative effects of GCC would 

contribute to the degradation of air quality resources in the geographic areas of 

interest (i.e., AQCR). For these reasons, the cumulative impacts on air quality 

during the license renewal term would be MODERATE.

Water resources

Waters of the Colorado River Basin have been extensively used, and the region 

has surface water planning, allocation, and development systems in place to 

manage the use of its limited surface water resources. Nevertheless, because of 

the potential impacts associated with water use conflicts and maintenance of 

Colorado River flows to Matagorda Bay, the cumulative impacts on surface water 

resources during the license renewal term would be MODERATE.

Because of the effective controls by the CPGCD on water use and because the 

STP operational leaks have not substantially affected the groundwater quality 

within the STP site, the cumulative impacts on groundwater resources during the 

license renewal term would be SMALL. 

Aquatic ecology

Future development of industries that compete for water in the Colorado River, 

such as WSEC, as well as management of water budgets across the State of 

Texas through diversion projects like the LCRA–SAWS Project and the Mary 

Rhodes Pipeline Phase II Project would likely affect aquatic resources in the 

lower Colorado River. Such actions, in combination with other direct and indirect 

anthropogenic and natural environmental stressors—including GCC—would 

cumulatively lead to effects on the aquatic communities that would noticeably 

alter important attributes, such as species range, habitat availability, ecosystem 

processes, migratory corridors and behavior, species diversity, and species 

abundance. For these reasons, the cumulative impacts on aquatic ecology 

during the license renewal term would be MODERATE.
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Resource Area Cumulative Impact

Terrestrial ecology

The staff examined the cumulative effects of the construction at STP 

(e.g., proposed STP, Units 3 and 4), neighboring projects, continued urbanization 

and habitat fragmentation, and nearby parks and wildlife preserves. The staff 

concludes that the minimal terrestrial impacts on the continued STP operations 

would not contribute to the overall decline in the condition of terrestrial resources. 

For these reasons, the cumulative impacts on terrestrial ecology during the 

license renewal term would be MODERATE.

Human health

The radiological dose limits for protection of the public and workers have been 

developed by the NRC and EPA to address the cumulative impact of acute and 

long-term exposure to radiation and radioactive material. The NRC and the State 

of Texas would regulate any future actions in the vicinity of the STP site that 

could contribute to cumulative radiological impacts. In addition, the cumulative 

radiological impacts from operation of STP, Units 1 and 2, the projected dry fuel 

storage system, and two additional reactor units would be required to meet the 

radiation dose limits in 10 CFR Part 20 and 40 CFR Part 190. For these reasons, 

cumulative radiological impacts during the license renewal term would be SMALL.

Socioeconomics

Since STPNOC has no plans to hire additional workers during the license renewal 

term, employment levels at STP would remain relatively constant, with no 

additional demand for housing, public utilities, public services, or increased traffic. 

Based on this information and other information presented in Chapter 4 of this 

SEIS, there would be no additional contributory effect on socioeconomic 

conditions in the future from the continued operation of STP during the license 

renewal term beyond what is currently being experienced (i.e., no cumulative 

impact). 

As discussed in Section 4.11.7, there would also be no disproportionately high 

and adverse impacts to minority and low-income populations from the continued 

operation of STP during the license renewal term. 

Historic & 

archaeological 

resources

As described in Sections 4.9.6 and 4.11.8, the continued operation of STP during 

the license renewal term would not incrementally contribute to the cumulative 

impacts on historic and archaeological resources within STP and in the 

surrounding area. Therefore, the cumulative impacts on historic and 

archaeological resources during the license renewal term would be SMALL.

4.12

2 10 CFR Part 20. Code of Federal Regulations, Title 10, Energy, Part 20, “Standards for 

3 protection against radiation.”

1 References

4 10 CFR Part 50. Code of Federal Regulations, Title 10, Energy, Part 50, “Domestic licensing of 

5 production and utilization facilities.”

6 10 CFR Part 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental 

7 protection regulations for domestic licensing and related regulatory functions.”

8 10 CFR Part 54. Code of Federal Regulations, Title 10, Energy, Part 54, “Requirements for 

9 renewal of operating licenses for nuclear power plants.”

10 36 CFR Part 60. Code of Federal Regulations, Title 36, Parks, Forests, and Public Property, 

11 Part 60, “National register of historic places.”
Environmental Impacts of Operation

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1 36 CFR Part 800. Code of Federal Regulations, Title 36, Parks, Forests, and Public Property, 

2 Part 800, “Protection of historic properties.” 

3 40 CFR Part 141. Code of Federal Regulations, Title 40, Protection of Environment, Part 141, 

4 “National primary drinking water regulations.” 

5 40 CFR Part 190. Code of Federal Regulations, Title 40, Protection of Environment, Part 190, 

6 “Environmental radiation protection standards for nuclear power operations.”

7 59 FR 7629. Executive Order 12898. Federal actions to address environmental justice in 

8 minority populations and low-income populations. Federal Register 59(32):7629–7634. 

9 February 16, 1994.

10 66 FR 65274. U.S. Environmental Protection Agency. National pollutant discharge elimination 

11 system: regulations addressing cooling water intake structures for new facilities; final rule. 

12 Federal Register. December 18, 2001.

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14 system—final regulations to establish requirements for cooling water intake structures at phase 

15 ii existing facilities; final rule. Federal Register. July 9, 2004.

16 69 FR 52040. U.S. Nuclear Regulatory Commission. Policy statement on the treatment of 

17 environmental justice matters in NRC regulatory and licensing actions. Federal Register. 

18 69(163):52040–52048. August 24, 2004.

19 76 FR 22174. U.S. Environmental Protection Agency. National pollutant discharge elimination 

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21 Federal Register. April 20, 2011. 

22 [AEC] U.S. Atomic Energy Commission. 1975. Final Environmental Statement Related to 

23 Operation of South Texas Project, Units 1 and 2. Houston Lighting & Power Company, City 

24 Public Service Board of San Antonio, Central Power and Light Company, City of Austin, Docket 

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27 [CAPS] Missouri Census Data Center Circular Area Profiling System. Version 10C. Using Data 

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32 <http://www.epa.gov/compliance/ej/resources/policy/ej_guidance_nepa_ceq1297.pdf> 

33 (accessed on April 6, 2012). ADAMS No. ML082520150.

34 Chemicals Inc. 2011. “Growing in Matagorda County.” Available at 

35 <http://www.chemicalsinc.com/Bay%20City%20Fact%20Sheet%20Rev.pdf> (accessed 

36 27 September 2011).

37 City of Corpus Christi. 2009. Garwood Pipeline Project, Project Update 2009. Corpus Christi, 

38 TX: Water Department. October 2, 2009. Available at 

39 <http://www.cctexas.com/files/g17/GarwoodCouncilPresentation100209.pdf> (accessed 

40 31 August 2011).

41 City of Corpus Christi. 2011. Lake Texana & Mary Rhodes Pipeline II. Corpus Christi, TX: 

42 Water Department. Available at 

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18 T. Tran, Project Manager, NRC. Subject: South Texas Project Federally listed species. March 

19 3, 2011. ADAMS No. ML110690848.

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38 Combined Licenses (COLs) for South Texas Project Electric Generating Station, Units 3 and 4. 

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43 Report. ADAMS No. ML11049A001.
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2 Advisory Council on Historic Preservation. Subject: South Texas Project, Units 1 and 2, license 

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5 Texas Historical Commission. Subject: South Texas Project, Units 1 and 2, license renewal 

6 application review. February 17, 2011. ADAMS No. ML110190549.

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8 Orms, FWS. Subject: Request for concurrence on list of Federally protected species. 

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11 STPNOC. Subject: Audit report regarding South Texas Project license renewal application—

12 cultural resources. July 18, 2011. ADAMS No. ML11173A304.

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14 to D. Bernhart, Assistant Southeast Regional Administrator for Protected Resources, NMFS. 

15 Subject: Request for list of Federally protected species and important habitats within the area 

16 under evaluation for the South Texas Project, Units 1 and 2, license renewal application review. 

17 February 16, 2011. ADAMS No. ML110190434. 

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19 Impact Statement Regarding Seabrook Station. NUREG-1437, Supplement 46. Office of 

20 Nuclear Reactor Regulation. Washington, DC. July 31, 2011. ADAMS No. ML11213A024.

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22 NRC, to L. Gaul, PhD, MPH, Epidemiologist, Emerging and Acute Infectious Diseases Branch,

23 TDSHS. Subject: NEPA consultation, waterborne outbreak. May 4, 2012. ADAMS No. 

24 ML12128A061. 

25 Ryder PD, Ardis AF. 2002. Hydrology of the Texas Gulf Coast Aquifer Systems, Regional 

26 Aquifer-Systems Analysis-Gulf Coast Plain. Reston, VA: U.S. Geological Survey. U.S. 

27 Geological Survey Professional Paper 1416-E.

28 [STPNOC] South Texas Project Nuclear Operating Company. 2007a. South Texas Project, 

29 Units 1 and 2. 2006 Annual Environmental and Annual Radiological Environmental Operating

30 Reports. Wadsworth, TX. ADAMS No. ML071270211.

31 [STPNOC] South Texas Project Nuclear Operating Company. 2007b. South Texas Project, 

32 Units 1 and 2. Radioactive Effluent Release Report for 2006. Wadsworth, Texas. ADAMS 

33 No. ML071280681.

34 [STPNOC] South Texas Project Nuclear Operating Company. 2008a. Letter from G Gibson, 

35 STPNOC, to NRC Document Control Desk. Subject: Response to RAIs. July 15, 2008. 

36 ADAMS No. ML082040684.

37 [STPNOC] South Texas Project Nuclear Operating Company. 2008b. Letter from G Gibson, 

38 STPNOC, to NRC Document Control Desk. Subject: South Texas Project, Units 3 and 4, 

39 Docket Nos. 52-012 and 52-013, Response to RAIs. July 2, 2008. ADAMS No. ML081970465.

40 [STPNOC] South Texas Project Nuclear Operating Company. 2008c. Letter from S Head, 

41 STPNOC, to NRC Document Control Desk. Subject: Response to RAIs. December 18, 2008. 

42 ADAMS No. ML090860873.
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1 [STPNOC] South Texas Project Nuclear Operating Company. 2008d. South Texas Project, 

2 Units 1 and 2. 2007 Annual Environmental and Annual Radiological Environmental Operating 

3 Reports. Wadsworth, TX. ADAMS No. ML081280093.

4 [STPNOC] South Texas Project Nuclear Operating Company (STPNOC). 2008e. South Texas 

5 Project, Units 1 and 2. Radioactive Effluent Release Report for 2007. Wadsworth, TX. ADAMS 

6 No. ML081300023.

7 [STPNOC] South Texas Project Nuclear Operating Company. 2009a. South Texas Project, 

8 Units 1 and 2. 2008 Annual Environmental and Annual Radiological Environmental Operating 

9 Reports. Wadsworth, TX. ADAMS No. ML091310066.

10 [STPNOC] South Texas Project Nuclear Operating Company. 2009b. South Texas Project, 

11 Units 1 and 2. Radioactive Effluent Release Report for 2008. Wadsworth, TX. ADAMS 

12 No. ML091200487.

13 [STPNOC] South Texas Project Nuclear Operating Company. 2009c. Updated Final Safety 

14 Analysis Report Units 1 and 2. Bay City, TX: STPEGS. Revision 15. April 29, 2010. ADAMS 

15 No. ML103220222.

16 [STPNOC] South Texas Project Nuclear Operating Company. 2009d. Water Conservation 

17 Plan, STP Nuclear Operating Company, South Texas Project Electric Generating Station, 

18 Certificate of Adjudication 14-5437 A. Revision 2. May 1, 2009. ADAMS No. ML11256A058.

19 [STPNOC] South Texas Project Nuclear Operating Company. 2010a. South Texas Project, 

20 Units 1 and 2. 2009 Annual Environmental and Annual Radiological Environmental Operating 

21 Reports. Wadsworth, TX. ADAMS No. ML101260530.

22 [STPNOC] South Texas Project Nuclear Operating Company. 2010b. South Texas Project, 

23 Units 1 and 2, License Renewal Application. Bay City, TX: STPNOC. “Environmental Report.” 

24 September 2010. ADAMS No. ML103010263.

25 [STPNOC] South Texas Project Nuclear Operating Company. 2010c. South Texas Project, 

26 Units 3 and 4, License Renewal Application. Bay City, TX: STPNOC. Part 3, “Environmental 

27 Report.” Revision 4. ADAMS No. ML102860592.

28 [STPNOC] South Texas Project Nuclear Operating Company. 2010d. South Texas Project, 

29 Units 1 and 2. Radioactive Effluent Release Report for 2009. Wadsworth, TX. ADAMS 

30 No. ML101090091.

31 [STPNOC] South Texas Project Nuclear Operating Company. 2011a. South Texas Project, 

32 Units 1 and 2. 2010 Annual Environmental and Annual Radiological Environmental Operating 

33 Reports. Wadsworth, TX. ADAMS No. ML111250429.

34 [STPNOC] South Texas Project Nuclear Operating Company. 2011b. Letter from AW Harrison, 

35 Manager Licensing, to NRC Document Control Desk. Subject: Transmittal of documents to 

36 support review of the STP LRA. TAC Nos. ME 4938 and ME 5122. STP Letter No.

37 NOC-AE-11002720. August 31, 2011. ADAMS Nos. ML11256A056 and ML11256A059. 

38 [STPNOC] South Texas Project Nuclear Operating Company. 2011c. Letter from G.T. Powell, 

39 Vice President, STPNOC, to NRC Document Control Desk. Subject: Response to RAI for the

40 STP LRA. TAC Nos. ME4938 and ME5122. STP Letter No. NOC-AE-11002719. 

41 September 6, 2011. ADAMS No. ML11255A211.

42 [STPNOC] South Texas Project Nuclear Operating Company. 2011d. South Texas Project, 

43 Units 1 and 2. Radioactive Effluent Release Report for 2010. Wadsworth, TX. ADAMS 

44 No. ML11124A121.
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1 [STPNOC] South Texas Project Nuclear Operating Company. 2011e. Letter from GT Powell, 

2 Vice President, STPNOC, to U.S. Nuclear Regulatory Commission, Document Control Desk. 

3 Subject: Response to RAI for the STP LRA. TAC Nos. ME4938 and ME5122. STP Letter No.

4 NOC-AE-11002723. September 12, 2011. ADAMS No. ML11259A014.

5 [STPNOC] South Texas Project Nuclear Operating Company. 2011f. Letter from D.W. 

6 Rencurrel, Senior Vice President, STPNOC, to U.S. Nuclear Regulatory Commission, 

7 Document Control Desk. Subject: Response to Requests for Additional Information for the 

8 South Texas Project License Renewal Application (TAC Nos. ME4938 and ME5122) (STP 

9 Letter Number NOC-AE-1002761). November 17, 2011. ADAMS No. ML11333A094.

10 [STPNOC] South Texas Project Nuclear Operating Company. 2011g. Letter from G.T. Powell, 

11 Vice President, STPNOC, to U.S. Nuclear Regulatory Commission, Document Control Desk. 

12 Subject: Response to Requests for Additional Information for the South Texas Project License 

13 Renewal Application (TAC Nos. ME4938 and ME5122) (STP Letter Number NOC-AE-1 

14 1002691). July 5, 2011. ADAMS No. ML11193A074. 

15 [TCEQ] Texas Commission on Environmental Quality. 2005. TPDES Permit 

16 No. WQ0001908000. Austin, TX.

17 [TCEQ] Texas Commission on Environmental Quality. 2007. Letter from K Holligan, TCEQ, to 

18 RA Gangluff, STPNOC. Subject: Cooling water intake structures Phase II rules; South Texas 

19 Project Electric Generating Station, TPDES Permit No. WQOOO 1908000. June 27, 2007. 

20 ADAMS No. ML 11256A057.

21 [TCEQ] Texas Commission on Environmental Quality. 2009. Amendment to Certificate of 

22 Adjudication, Certificate of Adjudication 14-5437 A. March 17, 2009. ADAMS 

23 No. ML11256A058. 

24 [TDSHS] Texas Department of State Health Services. “Radiation Branch Environmental 

25 Monitoring Summary Reports.” Available at 

26 <http://www.dshs.state.tx.us/radiation/publications.shtm>.

27 Texas Water Code, Title 2, Water Administration, Subtitle B, “Water Rights,” Chapter 11, “Water 

28 Rights.” Available at <http://www.statutes.legis.state.tx.us/Docs/WA/htm/WA.11.htm>. 

29 [TPWD] Texas Parks and Wildlife Department. 2002. Executive Summary: The Texas Shrimp 

30 Fishery. A report to the Governor and the 77th Legislature of Texas. Texas Parks and Wildlife 

31 Department. September 2002.

32 [TPWD] Texas Parks and Wildlife Department. 2005. Land and Water Resources Conservation 

33 and Recreation Plan. Austin, TX: TPWD. 137 p. Available at 

34 <http://www.tpwd.state.tx.us/publications/pwdpubs/pwd_pl_e0100_0867/> (accessed 

35 26 September 2011).

36 [TPWD] Texas Parks and Wildlife Department. 2010. “Prairie Pothole and Marsh Wetlands.” 

37 Available at <http://www.texaswetlands.org/prairie.htm> (accessed 26 September 2011).

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39 Volume II. Available at

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41 CHAPTER%202_REGIONAL%20K%20FINAL%20112706.pdf> (accessed 13 June 2011).

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43 Austin, TX: TWDB. Document No. GP-8-1. Volume 1. January 2007. Available at 

44 <http://www.twdb.state.tx.us/wrpi/swp/swp.asp> (accessed 31 August 2011).
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2 Information, 2012 Draft State Water Plan & Public Comments.” Available at 

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5 3-Year Estimate, American Community Survey. State and County QuickFacts on Lucas, 

6 Ottawa, Sandusky and Wood Counties, Ohio. Housing Characteristics for 2000 and 2006–

7 2008, 3-Year Estimate.” Available at <http://factfinder.census.gov> and 

8 <http://quickfacts.census.gov> (accessed April 2011). 

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10 Survey 5-year estimates and Data Profile Highlights information on Brazoria, Calhoun, Fort 

11 Bend, Jackson, Matagorda, Victoria, and Wharton Counties and State of Texas.” Available at 

12 <http://factfinder.census.gov and http://quickfacts.census.gov> (accessed March 2012). 

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14 United States. New York, NY: Cambridge University Press. Available at 

15 <http://downloads.globalchange.gov/usimpacts/pdfs/climate-impacts-report.pdf> (accessed 

16 31 August 2011). 

17 Wilber D.H. and R. Bass. 1998. “Effect of the Colorado River Diversion on Matagorda Bay 

18 Epifauna.” Estuarine, Coastal and Shelf Science (1998) 47:309–318.

5-1 

1 5.0 ENVIRONMENTAL IMPACTS OF POSTULATED ACCIDENTS

2 This chapter describes the environmental impacts from postulated accidents that might occur 

3 during the period of extended operation. The term “accident” refers to any unintentional event 

4 outside normal plant operations that results in a release, or the potential for a release, of 

5 radioactive materials into the environment. Two classes of postulated accidents are evaluated 

6 in the generic environmental impact statement (GEIS)—design-basis accidents (DBAs) and 

7 severe accidents (Table 5–1). 

8 Table 5–1. Issues Related to Postulated Accidents

9 Two issues related to postulated accidents are evaluated under the National Environmental 

10 Protection Act (NEPA) in the license renewal review—DBAs and severe accidents.

Issues Category

DBAs 1

Severe accidents 2

5.1

12 In order to receive U.S. Nuclear Regulatory Commission (NRC) approval to operate a nuclear 

13 power facility, an applicant for an initial operating license must submit a safety analysis report 

14 (SAR) as part of its application. The SAR presents the design criteria and design information for 

15 the proposed reactor and comprehensive data on the proposed site. The SAR also discusses 

16 various hypothetical accident situations and the safety features that are provided to prevent and 

17 mitigate accidents. The NRC staff (staff) reviews the application to determine if the plant design 

18 meets the NRC’s regulations and requirements and includes, in part, the nuclear plant design 

19 and its anticipated response to an accident.

11 Design Basis Accidents

20 DBAs are those accidents that both the applicant and the staff evaluate to ensure that the plant 

21 can withstand normal and abnormal transients and a broad spectrum of postulated accidents, 

22 without undue hazard to the health and safety of the public. Many of these postulated accidents 

23 are not expected to occur during the life of the plant but are evaluated to establish the design 

24 basis for the preventive and mitigative safety systems of the nuclear power plant. The 

25 acceptance criteria for DBAs are described in Title 10 of the Code of Federal Regulations

26 (CFR) Part 50 (10 CFR Part 50) and 10 CFR Part 100.

27 The environmental impacts of DBAs are evaluated during the initial licensing process, and the 

28 ability of the plant to withstand these accidents is demonstrated to be acceptable before 

29 issuance of the operating license. The results of these evaluations are found in applicant

30 documentation such as the applicant’s final safety analysis report (FSAR), the staff’s safety 

31 evaluation report (SER), the final environmental statement (FES), and Section 5.1 of this 

32 supplemental environmental impact statement (SEIS). An applicant is required to maintain the 

33 acceptable design and performance criteria throughout the life of the nuclear power plant, 

34 including the period of extended operation. The consequences for these events are evaluated 

35 for the hypothetical maximum exposed individual; as such, changes in the plant environment will 

36 not affect these evaluations. Because of the requirements that continuous acceptability of the 

37 consequences and aging management programs (AMPs) be in effect for the period of extended 

38 operation, the environmental impacts, as calculated for DBAs, should not differ significantly from 

39 initial licensing assessments over the life of the plant, including the period of extended 

40 operation. Accordingly, the design of the plant, relative to DBAs during the period of extended 
Environmental Impacts of Postulated Accidents

5-2 

1 operation, is considered to remain acceptable; therefore, the environmental impacts of those 

2 accidents were not examined further in the GEIS.

3 The Commission has determined that the environmental impacts of DBAs are of SMALL 

4 significance for all nuclear power plants because the plants were designed to successfully 

5 withstand these accidents. Therefore, for the purposes of license renewal, DBAs are 

6 designated as a Category 1 issue. The early resolution of the DBAs (i.e., successfully withstand 

7 these accidents) makes them a part of the current licensing basis (CLB) of the plant. The CLB 

8 of the plant is to be maintained by the applicant under its current license; therefore, in 

9 accordance with 10 CFR 54.30, it is not subject to review under license renewal.

10 No new and significant information related to the South Texas Project (STP) was identified 

11 during the review of the South Texas Project Nuclear Operating Company, LLC (STPNOC) 

12 Environmental Report (ER) (STPNOC 2010), site audit (NRC 2011), the scoping process

13 (NRC 2012), or evaluation of other available information. Therefore, there are no impacts 

14 related to these issues beyond those discussed in the GEIS. 

5.2

16 Severe nuclear accidents are those that are more severe than DBAs because they could result 

17 in substantial damage to the reactor core, whether or not there are serious offsite 

18 consequences. In the GEIS, the staff assessed the impacts of severe accidents during the 

19 period of extended operation, using the results of existing analyses and site-specific information 

20 to conservatively predict the environmental impacts of severe accidents for each plant during 

21 the period of extended operation.

15 Severe Accidents

22 Severe accidents initiated by external phenomena (e.g., tornadoes, floods, earthquakes, fires, 

23 and sabotage) have not traditionally been discussed in quantitative terms in FESs and were not 

24 specifically considered for the STP site in the GEIS (NRC 1996). However, the GEIS did 

25 evaluate existing impact assessments, including beyond design basis earthquakes, at existing 

26 plants—performed by NRC and by the industry at 44 nuclear plants in the U.S. In addition, the 

27 GEIS for license renewal performed a discretionary analysis of sabotages of plant systems in 

28 connection with license renewal. In the GEIS, the Commission concludes that the risk from 

29 sabotage and beyond design-basis earthquakes at existing plants is small and that the risks 

30 from other external events are adequately addressed by a generic consideration of internally 

31 initiated severe accidents (NRC 1996).

32 Based on information in the GEIS, the Commission found that:

33 The probability weighted consequences of atmospheric releases, fallout onto 

34 open bodies of water, releases to groundwater, and societal and economic 

35 impacts from severe accidents are small for all plants. However, alternatives to 

36 mitigate severe accidents must be considered for all plants that have not 

37 considered such alternatives.

38 The staff identified no new and significant information related to postulated accidents (DBAs and 

39 severe accidents) during the review of the STP ER (STPNOC 2010), site audit (NRC 2011), the 

40 scoping process (NRC 2012), or evaluation of other available information. Therefore, there are 

41 no impacts related to these issues beyond those discussed in the GEIS. However, in 

42 accordance with 10 CFR 51.53(c)(3)(ii)(L), the staff has reviewed severe accident mitigation 

43 alternatives (SAMAs) for STP. The results of the review are discussed in Section 5.3. 
Environmental Impacts of Postulated Accidents

5-3 

5.3

2 Section 10 CFR 51.53(c)(3)(ii)(L) requires that license renewal applicants consider alternatives 

3 to mitigate severe accidents if the staff has not previously evaluated SAMAs for the applicant’s 

4 plant in an environmental impact statement (EIS) or related supplement or in an environmental 

5 assessment. The purpose of this consideration is to ensure that plant changes (e.g., hardware, 

6 procedures, and training) with the potential for improving severe accident safety performance 

7 are identified and evaluated. SAMAs have not been previously considered for STP; therefore, 

8 the remainder of Chapter 5 addresses those alternatives.

1 Severe Accident Mitigation Alternatives

9 5.3.1 Overview of Severe Accident Mitigation Alternative Process

10 This section presents a summary of the SAMA evaluation for STP conducted by STPNOC, and 

11 the staff’s review of that evaluation. The staff performed its review with contract assistance from 

12 Pacific Northwest National Laboratory. The staff’s review is available in full in Appendix F of this 

13 SEIS, and the STPNOC’s SAMA evaluation is available in full in Attachment F of STPNOC’s ER

14 (LRA Appendix E).

15 STPNOC conducted the SAMA evaluation for STP with a four-step approach. In the first step, 

16 STPNOC quantified the level of risk associated with potential reactor accidents using the plant17 specific probabilistic risk assessment (PRA) and other risk models.

18 In the second step, STPNOC examined the major risk contributors and identified possible ways 

19 (SAMAs) of reducing that risk. Common ways of reducing risk are changes to components, 

20 systems, procedures, and training.

21 In the third step, STPNOC estimated the benefits and the costs associated with each of the 

22 candidate SAMAs. Estimates were made of how much each SAMA could reduce risk. Those 

23 estimates were developed in terms of dollars, in accordance with NRC guidance for performing 

24 regulatory analyses. STPNOC also estimated the costs of implementing the candidate SAMAs.

25 Finally, in the fourth step, STPNOC compared the cost and benefit of each of the remaining 

26 SAMAs to determine whether the SAMA was cost beneficial, meaning the benefits of the SAMA 

27 were greater than the cost (a positive cost benefit).

28 5.3.2 Estimate of Risk

29 STPNOC submitted an assessment of SAMAs for STP as part of the ER (STPNOC 2010). This 

30 assessment was based on the most recent STP PRA available at that time, a plant-specific 

31 offsite consequence analysis performed using the MELCOR Accident Consequence Code 

32 System 2 (MACCS2) computer code, and insights from the STP individual plant examination 

33 (IPE) and individual plant examination of external events (IPEEE) (HL&P 1992).

34 Two distinct analyses are combined to form the basis for the risk estimates used in the SAMA 

35 analysis. The first is the STP Level 1 and Level 2 PRA model, which is an updated version of 

36 the IPE (HL&P 1992) which, in turn, was an update of the earlier model completed for the 

37 purpose of supporting changes in certain STP technical specifications (NRC 1994). The second 

38 is a supplemental analysis of offsite consequences and economic impacts (essentially a Level 3 

39 PRA model) developed specifically for the SAMA analysis. The SAMA analysis is based on the 

40 most recent STP Level 1 and Level 2 PRA model available at the time of the ER, referred to as 

41 the STP_REV6 model. The scope of the Level 1 model includes internal and external initiating 

42 events. 
Environmental Impacts of Postulated Accidents

5-4 

1 The following results are based upon the STP model of record (STP_REV6), as presented in 

2 the ER (STPNOC 2010). The impact of the sensitivity analysis to updated fire and seismic data 

3 on the total core damage frequency (CDF) is provided in Appendix F, Sections F.2.2 (risk 

4 estimates) and F.6.2 (cost-benefit evaluation) of this SEIS.

The STP CDF is approximately 6.4×10-6 5 per year for both internal and external events as 

6 determined from quantification of the Level 1 PRA model. The CDF is based on the risk 

7 assessment for internally initiated events, which includes internal flooding, and external events, 

8 which includes fire, seismic events, external flooding, and tornado events. The internal events 

CDF is approximately 3.9×10-6 per year, and the external events CDF is approximately 2.5×10-6 9 

per year. The external events CDF includes contributions of approximately 1.0×10-6 10 per year 

due to fire events, 7.3×10-8 per year due to seismic events, and 1.4×10-6 11 per year due to other 

12 external events (STPNOC 2010). 

13 When determined from the sum of the containment event tree (CET) sequences, or Level 2 

PRA model, the CDF is approximately 6.2×10-6 14 per year (within acceptable approximation) for 

both internal and external events. The 6.2×10-6 15 value derived from the CET was used as the 

16 baseline CDF in the SAMA evaluations (STPNOC 2010).

17 The breakdown of CDF by initiating event is provided in Table 5–2, Table 5–3, Table 5–4, and 

18 Table 5–5 for internal, fire, seismic, and other external events, respectively (STPNOC 2011).

19
Environmental Impacts of Postulated Accidents

5-5 

1 Table 5–2. STP Core Damage Frequency for Internal Events

Initiating event (a) CDF

(per year)

% Contribution 

to internal events 

CDF(b, c)

% Contribution 

to total CDF

Loss of all offsite power 9.6×10-7 25 15

Loss of 345 kV offsite power 6.3×10-7 16 10

Steam generator tube rupture (SGTR) 4.4×10-7

 11 7

Excessive loss-of-coolant accident (LOCA) 3.2×10-7 8 5

Steam line break outside containment 2.8×10-7 7 4

Loss of electrical auxiliary building heating, 

ventilation, and air conditioning (HVAC) 

2.6×10-7 7 4

Turbine trip 1.8×10-7 5 3

Partial loss of main feedwater 1.5×10-7 4 2

Reactor coolant pump (RCP) seal LOCA 1.5×10-7 4 2 

Interfacing system LOCA 1.3×10-7 3 2

Loss of DC busses 9.7×10-8 2 2

Small LOCAs 7.5×10-8 2 1

Reactor trip 6.5×10-8 2 1

Other internal events 3.6×10-7 9 6

Total CDF (internal events) 3.9×10-6 100 64

(a) The impact of the sensitivity analysis to updated fire and seismic data on the total CDF is not included in these 

results. Section F.2.2 provides a discussion of these impacts.

(b) Obtained from CDF given in ER Table F.2-1 (STPNOC 2010) divided by the total internal events CDF of 

3.89×10-6. (c) May not total to 100 percent due to round off.

2 
Environmental Impacts of Postulated Accidents

5-6 

1 Table 5–3. STP Core Damage Frequency for Fire Events

Fire initiator description (a) CDF 

(per year)

% Contribution to 

fire CDF(b, c)

% Contribution to 

total CDF

Fire zone 047 scenario X 4.0×10-7 39 6

Fire zone 071 scenario X 2.1×10-7 21 3

Fire zone 047 scenario B 1.8×10-7 18 3 

Control room fire scenario 18 1.2×10-7 12 2

Fire zone 047 scenario BC 6.4×10-8 6 1

Control room fire scenario 23 2.6×10-8

 3 0.4

Fire zone 147 scenario O 1.1×10-8

 1 0.2

Control room fire scenario 10 1.0x10-9 <1 <0.1

Total CDF (fire events) 1.0×10-6 100 16

(a) The impact of the sensitivity analysis to updated fire and seismic data on the total CDF is not included in these 

results. Section F.2.2 provides a discussion of these impacts.

(b) Obtained from CDF given in ER Table F.2-1 (STPNOC 2010) divided by fire events CDF of 1.02×10-6. (c) May not total to 100 percent due to round off.

2 Table 5–4. STP Core Damage Frequency for Seismic Events

Initiating event(a) CDF

(per year)

% Contribution to 

seismic CDF (b, c)

% Contribution to 

total CDF

Seismic event, 0.4g acceleration 4.1×10-8 55 0.6

Seismic event, 0.6g acceleration 2.1×10-8 28 0.3

Seismic event, 0.2g acceleration 9.8×10-9 13 0.2

Seismic event, 0.1g acceleration 2.1×10-9 3 <0.1

Total CDF (seismic events) 7.3×10-8 100 1.1

(a) The impact of the sensitivity analysis to updated fire and seismic data on the total CDF is not included in these 

results. Section F.2.2 provides a discussion of these impacts.

(b) Obtained from CDF given in ER Table F.2-1 (STPNOC 2010) divided by seismic events CDF of 7.31×10-8. (c) May not total to 100 percent due to round off.

3 
Environmental Impacts of Postulated Accidents

5-7 

1 Table 5–5. STP Core Damage Frequency for Other External Events

Initiating event (a) CDF

(per year)

% Contribution 

to other external 

events CDF (b, c)

% Contribution 

to total CDF

Tornado induced failure of switchyard and 

essential cooling pond (ECP)

1.1×10-6 79 17

Essential cooling water (ECW) failure due to 

breach of main cooling reservoir (MCR)

2.9×10-7 21 5

External flooding scenarios 2–6 9.5×10-9 <1 0.2

Flood induced loss of offsite power (LOOP) 2.1×10-9 <1 <0.1

Total CDF (other external events) 1.4×10-6 100 22

(a) The impact of the sensitivity analysis to updated fire and seismic data on the total CDF is not included in these 

results. See Section F.2.2 for a discussion of these impacts.

(b) Obtained from CDF given in ER Table F.2-1 (STPNOC 2010) divided by other external events CDF of 1.41 × 10-6. (c) May not total to 100 percent due to round off.

2 As shown in Table 5–2, internal events contribute about 61 percent of the total CDF. The two 

3 LOOP events—“Loss of All Offsite Power” and “Loss of 345 kV Offsite Power”—are the largest 

4 contributors to the internal event CDF.

5 As shown in Table 5–5, the CDF for other external events make up the next largest contributor

6 (about 22 percent) of the total CDF. The “Tornado Induced Failure of Switchyard and Essential 

7 Cooling Pond (ECP)” and “Essential Cooling Water (ECW) Failure due to Breach of Main 

8 Cooling Reservoir (MCR)” are the largest contributors in this group. 

9 As shown in Table 5–3, fire events make up the next largest contributor (about 16 percent) of

10 the total CDF. The “Fire Zone 047 Scenario X” and “Fire Zone 071 Scenario X” are the largest 

11 contributors. Seismic events make up a small contribution of about 1 percent to the total STP 

CDF. Station blackout contributes about 35 percent (2.2×10-6 12 per year) of the total CDF while 

anticipated transients without scram (ATWS) contribute about 4 percent (2.8×10-7 13 per year) to 

14 the total CDF (STPNOC 2011).

15 In the ER, STPNOC estimated the dose to the population within 80 km (50 mi) of the STP site to 

16 be approximately 0.0174 person-Sievert (Sv) (1.74 person-roentgen equivalent man (rem)) per 

17 year. The breakdown of the total population dose by containment release mode is summarized 

18 in Table 5–6. Large early releases, with induced SGTR and interfacing systems loss of coolant 

19 accident (ISLOCA), are the dominant contributors to the population dose risk at STP. Small 

20 early releases with pre-existing small containment failure and late releases with no sprays are 

21 also significant contributors to the population dose risk. 

22
Environmental Impacts of Postulated Accidents

5-8 

1 Table 5–6. Breakdown of Population Dose by Containment Release Mode

Containment release mode (a)

Population dose 

(person-rem (b) 

per year) % Contribution

Large early releases (<3 hrs) 0.68 39

Small early releases (<3 hrs) 0.59 34

Late releases (>3 hrs) 0.42 24

Intact containment 0.05 3

Total 1.74 100

(a) The impact of the sensitivity analysis to updated fire and seismic data on the release category frequency is not 

included in these results. Section F.2.2 provides a discussion of these impacts.

(b) One person-rem=0.01 person-Sv 

2 The staff has reviewed STPNOC’s data and evaluation methods and concludes that the quality 

3 of the risk analyses is adequate to support an assessment of the risk reduction potential for 

4 candidate SAMAs. Accordingly, the staff based its assessment of offsite risk on the CDFs and 

5 offsite doses reported by STPNOC.

6 5.3.3 Potential Plant Improvements

7 STPNOC’s process for identifying potential plant improvements (SAMAs) consisted of the 

8 following elements:

9 • review of the dominant cutsets and most significant basic events from the 

10 current, plant-specific PRA,

11 • review of potential plant improvements identified in the STP IPE and IPEEE,

12 • review of SAMA candidates identified for license renewal applications for 

13 representative PWR plants, and

14 • review of other industry documentation discussing potential plant 

15 improvements.

16 Based on this process, an initial set of 21 candidate SAMAs, referred to as Phase I SAMAs, 

17 were identified. In Phase I of the evaluation, STPNOC performed a qualitative screening of the 

18 initial list of SAMAs and eliminated SAMAs from further consideration using the following 

19 criteria: 

20 • The SAMA is not applicable to STP due to design differences. 

21 • The SAMA has already been implemented at STP or would achieve results 

22 that have already been achieved at STP by other means. 

23 • The SAMA has estimated implementation costs that would exceed the dollar 

24 value associated with eliminating all severe accident risk at STP.

25 Based on this screening, 16 SAMAs were eliminated, leaving 5 SAMAs for further evaluation. A 

26 detailed cost-benefit analysis was performed for each of the 5 SAMAs in the Phase II analysis. 

27 STPNOC calculated the risk reduction that would be attributable to each candidate SAMA 

28 (assuming SAMA implementation) and re-quantified the risk value. The difference between the 

29 base risk value and the SAMA-reduced risk value is the averted risk, or the value of 

30 implementing the SAMA. STPNOC used this information in conjunction with the cost estimates 
Environmental Impacts of Postulated Accidents

5-9 

1 for implementing each SAMA to perform a detailed cost-benefit comparison. STPNOC 

2 performed additional analyses to evaluate how the SAMA results would change if certain key 

3 parameters were changed, including re-assessing the cost-benefit calculations using the 

4 95th percentile level of the failure probability distributions. The results of the uncertainty 

5 analysis are discussed in the ER, Attachment F, Section F.7. Based on the results of this 

6 SAMA analysis, none of the SAMAs have a positive net value, even when the 95th percentile 

7 PRA results were considered. Therefore, no SAMAs are being considered for implementation 

8 as part of license renewal (STPNOC 2010). The staff’s concerns regarding SAMAs were 

9 provided to STPNOC in RAIs (NRC 2011). The staff’s RAIs did not result in the identification of 

10 any potentially cost-beneficial SAMAs (STPNOC 2011). STPNOC’s SAMA analyses and the 

11 NRC’s review are discussed in more detail in the following sections. 

12 The NRC staff concludes that STPNOC used a systematic and comprehensive process for 

13 identifying potential plant improvements for STP and that the set of SAMAs evaluated in the ER, 

14 together with those evaluated in response to the NRC staff’s inquiries, is reasonably 

15 comprehensive and, therefore, is acceptable. 

16 5.3.4 Evaluation of Risk Reduction and Costs of Improvements

17 STPNOC estimated the costs of implementing the 21 SAMAs through the development of 

18 site-specific cost estimates and use of other applicants’ estimates for similar improvements. 

19 The costs were developed on a site basis (i.e., two units). If the cost estimate was for a single

20 unit, based on other applicants’ estimates for similar improvements, then the cost estimate was 

21 multiplied by two to derive the costs on a site basis. The site-specific cost estimates 

22 conservatively did not include contingency costs associated with unforeseen implementation 

23 obstacles or the cost of replacement power during extended outages required to implement the 

24 modifications (STPNOC 2010). The cost estimates that were based on other applicants’ 

25 estimates did not account for inflation, which is considered another conservatism.

26 STPNOC performed additional analyses to evaluate the impact of parameter choices and 

27 uncertainties on the results of the SAMA assessment. In this process, one additional SAMA 

28 was identified for detailed cost-benefit analysis.

29 The staff reviewed STPNOC’s basis for calculating the risk reduction for the various plant 

30 improvements and concludes that the rationale and assumptions for estimating risk reduction 

31 are reasonable and generally conservative (i.e., the estimated risk reduction is higher than what 

32 would actually be realized). Accordingly, the staff based its estimates of averted risk for the 

33 various SAMAs on STPNOC’s risk reduction estimates.

34 5.3.5 Cost-Benefit Comparison

35 The methodology used by STPNOC to perform the Cost-Benefit Comparison in the Phase II

36 analysis was based on NRC’s guidance for performing a cost-benefit analysis (i.e., 

37 NUREG/BR-0184, Regulatory Analysis Technical Evaluation Handbook (NRC 1997)). The 

38 guidance involves determining the net value for each SAMA. If the net value of a SAMA is 

39 negative, the cost of implementing the SAMA is larger than the benefit associated with the 

40 SAMA, and it is not considered cost-beneficial. Revision 4 of NUREG/BR-0058 states that two 

41 sets of estimates should be developed, one at a 3 percent discount rate and one at a 7 percent

42 discount rate (NRC 2004). STPNOC provided a base set of results using the 7 percent discount 

43 rate and a sensitivity study using the 3 percent discount rate. These results are presented in 

44 Table 5–7 as the total benefit baseline and total benefit baseline with uncertainty. Table 5–7

45 lists (a) the assumptions considered to estimate the risk reduction for each of the evaluated 

46 SAMAs, (b) the estimated risk reduction in terms of percent reduction in CDF and population 
Environmental Impacts of Postulated Accidents

5-10

1 dose, and (c) the estimated total benefit (present value) of the averted risk. The estimated 

2 benefits reported in Table 5–7 reflect the combined benefit in both internal and external events. 

3 There are six SAMAs listed in Table 5–7. The associated initiated events for these six SAMAs 

are: 4 

5 • cable spreading room fire, 

6 • ISLOCA, 

7 • SGTR, 

8 • loss of reactor coolant system (RCS) water seal, 

9 • loss of standby diesel generator (SBDG) HVAC, and

10 • loss of essential cooling water intake structure (ECWIS) HVAC, respectively. 

11 The staff reviewed the bases for the applicant’s cost estimates. For certain improvements, the 

12 staff also compared the cost estimates to estimates developed elsewhere for similar 

13 improvements, including estimates developed as part of other applicants’ analyses of SAMAs 

14 for operating reactors. The staff reviewed the costs and has found them to be reasonable and 

15 generally consistent with estimates provided in support of other plants’ analyses. The staff 

16 agrees that the costs of the SAMAs evaluated would be higher than the associated benefits 

17 when they are considered independently.

18 Table 5–7. Phase II SAMA List (Cost-Benefit) for STP

SAMA(a) Assumptions

% Risk reduction Total benefit ($)

Cost ($)

CDF(b)

Population 

dose (% dose 

reduction)

Baseline 

(internal 

+ external)

Baseline with 

uncertainty(b)

3b(c)—Install fire 

wrap on positive 

displacement 

pump (PDP) 

cables in cable 

spreading room.

Eliminate failure of the 

PDP due to a fire in 

the cable spreading 

room.

<1 <1 3K 4K 800K

4—Develop 

procedures to 

isolate component 

cooling water 

(CCW) inside 

containment.

Eliminate failure of the 

operator action to 

isolate CCW.

2 10 27K 43K 100K
Environmental Impacts of Postulated Accidents

5-11

SAMA(a) Assumptions

% Risk reduction Total benefit ($)

Cost ($)

CDF(b)

Population 

dose (% dose 

reduction)

Baseline 

(internal 

+ external)

Baseline with 

uncertainty(b)

10—Enhance 

procedures to 

ensure the steam 

generators (SGs) 

are filled or 

maintain filled in 

SGTR events to 

scrub fission 

products.

Reassign a portion of 

the SGTR CDF 

contribution for the 

large early release 

category (7.48E-06 

per year) and late 

release category 

(1.35E-07 per year) to 

the small early release 

category and intact 

containment release 

category, respectively. 

0 2 3K 5K 100K

12—Enhance 

procedures to 

prevent clearing of 

RCS cold leg 

water seals.

Reassign the induced 

SGTR CDF 

contribution (2.4E-09 

per year) for 

sequences in which 

offsite power is 

available from the 

large early release 

category to the intact 

containment release 

category.

0 0 <1K <1K 100K

13—Develop 

procedures to 

open doors or use 

portable fans for 

alternate SBDG

room cooling.

Eliminate failure of the 

operator action to 

provide SBDG room 

cooling.

<1 0 1K 2K 100K

15—Develop 

emergency 

procedures for 

alternate ECWIS 

room cooling.

Eliminate failure of the 

operator action to 

provide ECWIS room 

cooling.

1 2 8K 12K 100K

(a) SAMAs in bold are potentially cost-beneficial.

(b) Baseline benefits increased by a factor of 1.6 to account for uncertainties, which is discussed further in Section F.6.2.

(c) SAMA 3b retained for Phase II analysis based on results of uncertainty analysis, which is discussed further in 

Section F.6.2. 

1 5.3.6 Conclusions

2 The NRC staff reviewed the STPNOC’s analysis. The staff concludes that the methods used 

3 and the implementations of those methods were sound. The treatment of SAMA benefits and 

4 costs supports the general conclusion that the SAMA evaluations performed by STPNOC are 

5 reasonable and sufficient for the license renewal submittal. 
Environmental Impacts of Postulated Accidents

5-12

1 The staff agrees with STPNOC’s conclusion that none of the candidate SAMAs are potentially 

2 cost beneficial. This conclusion is based on the generally conservative treatment of costs and 

3 benefits. This conclusion is consistent with the low residual level of risk indicated in the STP 

4 PRA and the fact that STPNOC has already implemented the plant improvements identified 

5 from the IPE and IPEEE.

5.4

7 10 CFR Part 50. Code of Federal Regulations, Title 10, Energy, Part 50, “Domestic Licensing of 

8 Production and Utilization Facilities.” 

6 References

9 10 CFR Part 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental 

10 protection regulations for domestic licensing and related regulatory functions.” 

11 10 CFR Part 54. Code of Federal Regulations, Title 10, Energy, Part 54, “Requirements for 

12 Renewal of Operating Licenses for Nuclear Power Plants.” 

13 10 CFR Part 100. Code of Federal Regulations, Title 10, Energy, Part 100, “Reactor Site 

14 Criteria.” 

15 [HL&P] Houston Lighting and Power Company. 1992. “South Texas Project Electric 

16 Generating Station Level 2 Probabilistic Safety Assessment and Individual Plant Examination.” 

17 August 1992. (ADAMS Nos. ML0617001702, ML0617001790, ML0617001850).

18 [NRC] U.S. Nuclear Regulatory Commission. 1994. Letter from Suzanne C. Black, Director, to 

19 William T. Cottle, Houston Lighting & Power Company. Subject: Issuance of Amendment 

20 Nos. 59 and 47 to Facility Operating License Nos. NPF-76 and NPF-80 and Related Relief 

21 Request—South Texas Project, Units 1 and 2 (TAC Nos. M76048 and M76049). 

22 February 17, 1994. ADAMS No. ML021300134.

23 [NRC] U.S. Nuclear Regulatory Commission. 1996. Generic Environmental Impact Statement 

24 for License Renewal of Nuclear Plants. Washington, DC. NRC NUREG-1437. May 1996. 

25 ADAMS Nos. ML040690705 and ML040690738.

26 [NRC] U.S. Nuclear Regulatory Commission. 1997. Regulatory Analysis Technical Evaluation 

27 Handbook. Washington, DC. NRC. NUREG/BR-0184. January 1997. ADAMS 

28 No. ML050190193.

29 [NRC] U.S. Nuclear Regulatory Commission. 2004. Regulatory Analysis Guidelines of the U.S. 

30 Nuclear Regulatory Commission. Washington, DC. NRC NUREG/BR-0058, Rev. 4. July 2000. 

31 ADAMS No. ML003738939.

32 [NRC] U.S. Nuclear Regulatory Commission. 2011. Summary of site audit related to the review 

33 of the license renewal application for South Texas Project, Units 1 and 2. August 4, 2011. 

34 ADAMS No. ML11196A005.

35 [NRC] U.S. Nuclear Regulatory Commission. 2012. Environmental Impact Statement Scoping 

36 Process, Summary Report, South Texas Project, Units 1 and 2, Bay City, TX. Washington, DC. 

37 NRC. 2012. ADAMS No. ML11153A082.

38 [STPNOC] South Texas Project Nuclear Operating Company. 2010. “South Texas Project, 

39 Applicant’s Environmental Report—Operating License Renewal Stage, South Texas Project 

40 Units 1 & 2.” September 2010. ADAMS No. ML103010263.

41 [STPNOC] South Texas Project Nuclear Operating Company. 2011. Letter from G.T. Powell, 

42 STPNOC, to U.S. Nuclear Regulatory Commission Document Control Desk, Subject: South 

43 Texas Project Units 1 and 2, Docket Nos. STN 50-498, STN 50-499, Response to Request for 
Environmental Impacts of Postulated Accidents

5-13

1 Additional Information on South Texas Project License Renewal Application (TAC No. ME4938). 

2 July 5, 2011. ADAMS No. ML11193A016.

3 [STPNOC] South Texas Project Nuclear Operating Company. 2011b. Letter from G.T. Powell, 

4 STPNOC, to U.S. Nuclear Regulatory Commission Document Control Desk, Subject: South 

5 Texas Project Units 1 and 2, Docket Nos. STN 50-498, STN 50-499, Response to Request for 

6 Additional Information on South Texas Project License Renewal Application (TAC No. ME4938). 

7 August 23, 2011. ADAMS No. ML11250A067.

8 [STPNOC] South Texas Project Nuclear Operating Company. 2012b. Letter from D.W. 

9 Rencurrel, STPNOC, to U.S. Nuclear Regulatory Commission Document Control Desk, Subject: 

10 South Texas Project Units 1 and 2, Docket Nos. STN 50-498, STN 50-499, Clarification to 

11 Supplemental Response to Request for Additional Information on South Texas Project License 

12 Renewal Application—SAMA (TAC Nos. ME4938 and ME5122). February 16, 2012. ADAMS 

13 No. ML12053A259.

6-1 

1 6.0 ENVIRONMENTAL IMPACTS OF THE URANIUM FUEL CYCLE, 

2 WASTE MANAGEMENT, AND GREENHOUSE GAS EMISSIONS 

3 This chapter addresses issues related to the uranium fuel cycle, solid waste management, and 

4 greenhouse gas (GHG) emissions during the proposed 20-year period of extended operation.

6.1

6 The uranium fuel cycle includes uranium mining and milling, the production of uranium 

7 hexafluoride, isotopic enrichment, fuel fabrication, reprocessing of irradiated fuel, transportation 

8 of radioactive materials, and management of low-level wastes and high-level wastes related to 

9 uranium fuel cycle activities. The generic potential impacts of the radiological and 

10 non-radiological environmental impacts of the uranium fuel cycle and transportation of nuclear 

11 fuel and wastes are described in detail in NUREG-1437, Generic Environmental Impact 

12 Statement (GEIS) for License Renewal of Nuclear Plants (NRC 1996, 1999) based, in part, on 

13 the generic impacts given in Table S–3, “Table of Uranium Fuel Cycle Environmental Data,” 

14 located at Title 10, Part 51.51, of the Code of Federal Regulations (10 CFR 51.51), and in 

15 10 CFR 51.52(c), Table S–4, “Environmental Impact of Transportation of Fuel and Waste to and 

16 from One Light-Water-Cooled Nuclear Power Reactor.”

5 The Uranium Fuel Cycle

17 In the GEIS, the U.S. Nuclear Regulatory Commission (NRC) staff identified nine Category 1 

18 issues related to the fuel cycle and waste management, which appear in Table 6–1. There are 

19 no Category 2 issues related to the fuel cycle and waste management.

20 Table 6–1. Issues Related to the Uranium Fuel Cycle and Waste Management

Issues GEIS Sections Category

Offsite radiological impacts (individual effects 

from other than the disposal of spent fuel & 

high-level waste)

6.1; 6.2.1; 6.2.2.1; 6.2.2.3; 6.2.3; 6.2.4; 6.6 1 

Offsite radiological impacts (collective effects) 6.1; 6.2.2.1; 6.2.3; 6.2.4; 6.6 1 

Offsite radiological impacts (spent fuel and 

high-level waste disposal)

6.2.2.1; 6.2.2.2; 6.2.3; 6.2.4 1 

Nonradiological impacts of the uranium fuel 

cycle

6.1; 6.2.2.6; 6.2.2.7; 6.2.2.8; 6.2.2.9; 6.2.3; 6.2.4; 

6.6 1 

Low-level waste storage & disposal

6.1; 6.2.2.2;6.4.2; 6.4.3; 6.4.3.1; 6.4.3.2; 6.4.3.3; 

6.4.4; 6.4.4.1; 6.4.4.2; 6.4.4.3; 6.4.4.4; 6.4.4.5; 

6.4.4.5.1; 6.4.4.5.2; 6.4.4.5.3; 6.4.4.5.4; 

6.4.4.6;6.6

1 

Mixed waste storage & disposal 6.4.5.1; 6.4.5.2; 6.4.5.3; 6.4.5.4; 6.4.5.5; 6.4.5.6; 

6.4.5.6.1; 6.4.5.6.2; 6.4.5.6.3; 6.4.5.6.4; 6.6 1 

Onsite spent fuel 6.1; 6.4.6; 6.4.6.1; 6.4.6.2; 6.4.6.3; 6.4.6.4; 

6.4.6.5; 6.4.6.6; 6.4.6.7; 6.6 1 

Nonradiological waste 6.1; 6.5; 6.5.1; 6.5.2; 6.5.3; 6.6 1

Transportation 6.1; 6.3.1; 6.3.2.3; 6.3.3; 6.3.4; 6.6, Addendum 1 1
Environmental Impacts of the Uranium Fuel Cycle, 

Waste Management, and Greenhouse Gas Emissions

6-2 

1 The issue, “offsite radiological impacts (spent fuel and high-level waste disposal),” from 

2 Table 6-1, is not evaluated in this environmental impact statement (EIS), as explained later in 

3 this section. For the term of license renewal, the NRC staff did not identify any new and 

4 significant information related to the remaining uranium fuel cycle and waste management 

5 issues listed in Table 6-1 during its review of the STP Nuclear Operating Company (STPNOC) 

6 Environmental Report (STPNOC 2010), the site visit, and the scoping process. Therefore, there 

7 are no impacts related to these issues beyond those discussed in the GEIS. For these 

8 Category 1 issues, the GEIS concludes that the impacts are SMALL, except for the offsite 

9 radiological impacts (collective effects) from the uranium fuel cycle and waste management, 

10 which the NRC concluded are acceptable. 

11 However, the offsite radiological impacts resulting from spent fuel and high-level waste disposal, 

12 that will occur after the reactors have been permanently shut down, are addressed in the 

13 Commission’s Waste Confidence Decision Rule (WCD), 10 CFR 51.23. In 2010, the 

14 Commission revised the WCD (i.e., WCD Update) to reflect information gained based on 

15 experience in the storage of spent nuclear fuel and the increased uncertainty in the siting and 

16 construction of a permanent geologic repository for the disposal of spent nuclear fuel. 

17 On June 8, 2012, the United States Court of Appeals for the District of Columbia Circuit 

18 (New York v. NRC, 681 F.3d 471 (D.C. Cir. 2012)), in response to a legal challenge to the 

19 WCD, vacated the NRC’s WCD Update (75 Federal Register (FR) 81,032 and 75 FR 81,037). 

20 The court decision was based on grounds relating to aspects of the National Environmental 

21 Policy Act (NEPA). The court decision held that the WCD Update is a major Federal action 

22 necessitating either an EIS or a finding of no significant environmental impact (FONSI), and the 

23 Commission’s evaluation of the risks associated with the storage of spent nuclear fuel for at 

24 least 60 years beyond the licensed life for reactor operation is deficient. 

25 In response to the court’s ruling, the Commission, in CLI-12-16 (NRC 2012), determined that it

26 would not issue licenses dependent upon the WCD until the issues identified in the court’s 

27 decision are appropriately addressed. In CLI-12-16, the Commission also noted that this 

28 determination extends only to final license issuance; all current licensing reviews and 

29 proceedings should continue to move forward.

30 In addition, the Commission directed (SRM-COMSECY-12-0016) the NRC staff to proceed with 

31 a rulemaking that includes the development of an EIS to support an updated WCD within 

32 24 months (by September 2014). The Commission indicated that the EIS used to support the 

33 revised rule should build on the information already documented in various NRC studies and 

34 reports on the impacts associated with the storage of spent nuclear fuel that were developed as 

35 part of the 2010 WCD Update. It should primarily focus additional analyses on the deficiencies 

36 identified in the D.C. Circuit’s decision. The NRC considers the WCD to be a generic issue that 

37 is best addressed through rulemaking and that the NRC rulemaking process provides an 

38 appropriate forum for public review and comment on both the draft EIS and the proposed WCD. 

39 The updated rule and supporting EIS will provide the necessary NEPA analyses of waste 

40 confidence-related human health and environmental issues. As directed by the Commission, 

41 the NRC will not issue a renewed license prior to the resolution of waste confidence-related

42 issues. This will ensure that there would be no irretrievable or irreversible resource 

43 commitments or potential harm to the environment before waste confidence impacts have been 

44 addressed.

45 If the results of the WCD EIS identify information that requires a supplement to this EIS, the 

46 NRC staff will perform any appropriate additional NEPA review for those issues before the NRC 

47 makes a final licensing decision.
Environmental Impacts of the Uranium Fuel Cycle, 

Waste Management, and Greenhouse Gas Emissions

6-3 

6.2

2 This section discusses the potential impacts from GHGs emitted from the nuclear fuel cycle. 

3 The GEIS does not directly address these emissions, and its discussion is limited to an 

4 inference that substantial carbon dioxide emissions may occur if coal- or oil-fired alternatives to 

5 license renewal are carried out.

1 Greenhouse Gas Emissions

6 6.2.1 Existing Studies 

7 Since the development of the GEIS, the relative volumes of GHGs emitted by nuclear and other 

8 electricity generating methods have been widely studied. However, estimates and projections 

9 of the carbon footprint of the nuclear power lifecycle vary depending on the type of study done. 

10 Additionally, considerable debate also exists among researchers on the relative effects of 

11 nuclear and other forms of electricity generation on GHG emissions. Existing studies on GHG 

12 emissions from nuclear power plants generally take two different forms:

13 (1) qualitative discussions of the potential to use nuclear power to reduce GHG 

14 emissions and mitigate global warming, and

15 (2) technical analyses and quantitative estimates of the actual amount of GHGs 

16 generated by the nuclear fuel cycle or entire nuclear power plant life cycle and 

17 comparisons to the operational or life cycle emissions from other energy generation 

18 alternatives. 

19 Qualitative Studies. The qualitative studies consist primarily of broad evaluations, large-scale 

20 public policy evaluations, or investment evaluations of whether an expansion of nuclear power is 

21 likely to be a technically, economically, or politically workable means of achieving global GHG 

22 reductions. Studies found by the staff during the subsequent literature search include the 

23 following:

24 • Evaluations to determine if investments in nuclear power in developing 

25 countries should be accepted as a flexibility mechanism to assist 

26 industrialized nations in achieving their GHG reduction goals under the Kyoto 

27 Protocols (IAEA 2000; NEA 2002; Schneider 2000). Ultimately, the parties to 

28 the Kyoto Protocol did not approve nuclear power as a component under the 

29 clean development mechanism (CDM) due to safety and waste disposal 

30 concerns (NEA 2002).

31 • Analyses developed to assist governments, including the U.S. Government, 

32 in making long-term investment and public policy decisions in nuclear power 

33 (Hagen et al. 2001; Keepin 1988; MIT 2003).

34 Although the qualitative studies sometimes reference and critique the existing quantitative 

35 estimates of GHGs produced by the nuclear fuel cycle or life cycle, their conclusions generally 

36 rely heavily on discussions of other aspects of nuclear policy decisions and investment such as 

37 safety, cost, waste generation, and political acceptability. Therefore, these studies are typically 

38 not directly applicable to an evaluation of GHG emissions associated with the proposed license 

39 renewal for a given nuclear power plant.

40 Quantitative Studies. A large number of technical studies, including calculations and estimates 

41 of the amount of GHGs emitted by nuclear and other power generation options, are available in 

42 the literature and were useful to the staff’s efforts in addressing relative GHG emission levels. 

43 Examples of these studies include—but are not limited to—Mortimer (1990), 
Environmental Impacts of the Uranium Fuel Cycle, 

Waste Management, and Greenhouse Gas Emissions

6-4 

1 Andseta et al. (1998), Spadaro (2000), Storm van Leeuwen and Smith (2008), Fritsche (2006), 

2 Parliamentary Office of Science and Technology (POST) (2006), Atomic Energy Authority 

3 (AEA) (2006), Weisser (2006), Fthenakis and Kim (2007), and Dones (2007).

4 Comparing these studies and others like them is difficult because the assumptions and 

5 components of the lifecycles the authors evaluate vary widely. Examples of areas in which 

6 differing assumptions make comparing the studies difficult include the following:

7 • energy sources that may be used to mine uranium deposits in the future,

8 • reprocessing or disposal of spent nuclear fuel,

9 • current and potential future processes to enrich uranium and the energy 

10 sources that will power them,

11 • estimated grades and quantities of recoverable uranium resources,

12 • estimated grades and quantities of recoverable fossil-fuel resources,

13 • estimated GHG emissions other than carbon dioxide, including the 

14 conversion to carbon dioxide equivalents per unit of electric energy produced,

15 • performance of future fossil-fuel power systems,

16 • projected capacity factors for alternatives means of generation, and

17 • current and potential future reactor technologies.

18 In addition, studies may vary with respect to whether all or parts of a power plant’s lifecycle are 

19 analyzed (i.e., a full lifecycle analysis will typically address plant construction, operations, 

20 resource extraction (for fuel and construction materials), and decommissioning, whereas a 

21 partial lifecycle analysis primarily focuses on operational differences). 

22 In the case of license renewal, a GHG analysis for that portion of the plant’s lifecycle (operation 

23 for an additional 20 years) would not involve GHG emissions associated with construction 

24 because construction activities have already been completed at the time of relicensing. In

25 addition, the proposed action of license renewal would also not involve additional GHG 

26 emissions associated with facility decommissioning because that decommissioning must occur 

27 whether the facility is relicensed or not. However, in some of the above-mentioned studies, the 

28 specific contribution of GHG emissions from construction, decommissioning, or other portions of 

29 a plant’s lifecycle cannot be clearly separated from one another. In such cases, an analysis of 

30 GHG emissions would overestimate the GHG emissions attributed to a specific portion of a 

31 plant’s lifecycle. Nonetheless, these studies supply some meaningful information with respect 

32 to the relative magnitude of the emissions among nuclear power plants and other forms of 

33 electric generation, as discussed in the following sections.

34 In Table 6–2, Table 6–3, and Table 6–4, the staff presents the results of the above-mentioned 

35 quantitative studies to supply a weight-of-evidence evaluation of the relative GHG emissions 

36 that may result from the proposed license renewal as compared to the potential alternative use 

37 of coal-fired, natural gas-fired, and renewable generation. Most studies from Mortimer (1990) 

38 onward suggest that uranium ore grades and uranium enrichment processes are leading 

39 determinants in the ultimate GHG emissions attributable to nuclear power generation. These 

40 studies show that the relatively lower order of magnitude of GHG emissions from nuclear power, 

41 when compared to fossil-fueled alternatives (especially natural gas), could potentially disappear 

42 if available uranium ore grades drop sufficiently while enrichment processes continued to rely on 

43 the same technologies.
Environmental Impacts of the Uranium Fuel Cycle, 

Waste Management, and Greenhouse Gas Emissions

6-5 

1 Summary of Nuclear Greenhouse Gas Emissions Compared to Coal. Considering that coal 

2 fuels the largest share of electricity generation in the U.S. and that its burning results in the 

3 largest emissions of GHGs for any of the likely alternatives to nuclear power generation, 

4 including South Texas Project (STP), most of the available quantitative studies focused on 

5 comparisons of the relative GHG emissions of nuclear to coal-fired generation. The quantitative 

6 estimates of the GHG emissions associated with the nuclear fuel cycle (and, in some cases, the 

7 nuclear lifecycle), as compared to an equivalent coal-fired plant, are presented in Table 6–2. 

8 The staff considered the best available information for its independent analysis. Although the 

9 following chart does not include all existing studies, it gives an illustrative range of estimates 

10 developed by various sources.

11 Table 6–2. Nuclear Greenhouse Gas Emissions Compared to Coal

Source GHG Emission Results

Mortimer (1990) Nuclear—230,000 tons CO2

(a)

Coal—5,912,000 tons CO2

Note: Future GHG emissions from nuclear to increase because of 

declining ore grade.

Andseta et al. (1998) Nuclear energy produces 1.4% of the GHG emissions compared to coal.

Note: Future reprocessing and use of nuclear-generated electrical 

power in the mining and enrichment steps are likely to change the 

projections of earlier authors, such as Mortimer (1990).

Spadaro (2000) Nuclear—2.5–5.7 g Ceq/kWh

Coal—264–357 g Ceq/kWh

Fritsche (2006) (Values 

estimated from graph in 

Figure 4)

Nuclear—33 g Ceq/kWh

Coal—950 g Ceq/kWh

POST (2006) (Nuclear 

calculations from AEA 2006)

Nuclear—5 g Ceq/kWh

Coal—>1,000 g Ceq/kWh

Note: Decrease of uranium ore grade to 0.03% would raise nuclear to 

6.8 g Ceq/kWh. Future improved technology and carbon capture and 

storage could reduce coal-fired GHG emissions by 90%.

Weisser (2006) (Compilation of 

results from other studies)

Nuclear—2.8–24 g Ceq/kWh

Coal—950–1,250 g Ceq/kWh

(a) CO2 is carbon dioxide.

12 6.2.1.2 Summary of Nuclear Greenhouse Gas Emissions Compared to Natural Gas

13 The quantitative estimates of the GHG emissions associated with the nuclear fuel cycle (and, in 

14 some cases, the nuclear lifecycle), as compared to an equivalent natural gas-fired plant, are 

15 presented in Table 6–3. In considering the best available information for its independent 

16 analysis, the staff noted that the following chart does not include all existing studies; however, it 

17 gives an illustrative range of estimates developed by various sources.
Environmental Impacts of the Uranium Fuel Cycle, 

Waste Management, and Greenhouse Gas Emissions

6-6 

1 Table 6–3. Nuclear Greenhouse Gas Emissions Compared to Natural Gas

Source GHG Emission Results

Spadaro (2000) Nuclear—2.5–5.7 g Ceq/kWh

Natural Gas—120–188 g Ceq/kWh

Storm van Leeuwen & Smith 

(2008)

Nuclear fuel cycle produces 20–33% of the GHG emissions compared 

to natural gas (at high ore grades).

Note: Future nuclear GHG emissions to increase because of declining 

ore grade.

Fritsche (2006) (Values 

estimated from graph in 

Figure 4)

Nuclear—33 g Ceq/kWh

Cogeneration Combined Cycle Natural Gas—150 g Ceq/kWh

POST (2006) (Nuclear 

calculations from AEA 2006)

Nuclear—5 g Ceq/kWh

Natural Gas—500 g Ceq/kWh

Note: Decrease of uranium ore grade to 0.03% would raise nuclear to 

6.8 g Ceq/kWh. Future improved technology and carbon capture and 

storage could reduce natural gas GHG emissions by 90%.

Weisser (2006) (Compilation of 

results from other studies)

Nuclear—2.8–24 g Ceq/kWh

Natural Gas—440–780 g Ceq/kWh

Dones (2007) Author critiqued methods and assumptions of Storm van Leeuwen and 

Smith (2005) and concluded that the nuclear fuel cycle produces 

15–27% of the GHG emissions of natural gas.

2 Summary of Nuclear Greenhouse Gas Emissions Compared to Renewable Energy Sources. 

3 The quantitative estimates of the GHG emissions associated with the nuclear fuel cycle, as 

4 compared to equivalent renewable energy sources, are presented in Table 6–4. Calculation of 

5 GHG emissions associated with these sources is more difficult than the calculations for nuclear 

6 energy and fossil fuels because of the large variation in efficiencies due to their different 

7 sources and locations. For example, the efficiency of solar and wind energy is highly dependent 

8 on the location in which the power generation facility is installed. Similarly, the range of GHG 

9 emissions estimates for hydropower varies greatly, depending on the type of dam or reservoir 

10 involved (if used at all). Therefore, the GHG emissions estimates for these energy sources 

11 have a greater range of variability than the estimates for nuclear and fossil-fuel sources. As 

12 noted in Section 6.2.1.2, the following chart gives an illustrative range of estimates developed 

13 by various sources.
Environmental Impacts of the Uranium Fuel Cycle, 

Waste Management, and Greenhouse Gas Emissions

6-7 

1 Table 6–4. Nuclear Greenhouse Gas Emissions Compared to 

2 Renewable Energy Sources

Source GHG Emission Results

Mortimer (1990) Nuclear—230,000 tons CO2

Hydropower—78,000 tons CO2

Wind power—54,000 tons CO2

Tidal power—52,500 tons CO2

Note: Future GHG emissions from nuclear are expected to increase 

because of declining ore grade.

Spadaro (2000) Nuclear—2.5–5.7 g Ceq/kWh

Solar PV—27.3–76.4 g Ceq/kWh

Hydroelectric—1.1–64.6 g Ceq/kWh

Biomass—8.4–16.6 g Ceq/kWh

Wind—2.5–13.1 g Ceq/kWh

Fritsche (2006) (Values 

estimated from graph in 

Figure 4)

Nuclear—33 g Ceq/kWh

Solar PV—125 g Ceq/kWh

Hydroelectric—50 g Ceq/kWh

Wind—20 g Ceq/kWh

POST (2006) (Nuclear 

calculations from AEA 2006)

Nuclear—5 g Ceq/kWh

Biomass—25–93 g Ceq/kWh

Solar PV—35–58 g Ceq/kWh

Wave/Tidal—25–50 g Ceq/kWh

Hydroelectric—5–30 g Ceq/kWh

Wind—4.64–5.25 g Ceq/kWh

Note: Decrease of uranium ore grade to 0.03% would raise nuclear to 

6.8 g Ceq/kWh. 

Weisser (2006) (Compilation of 

results from other studies)

Nuclear—2.8–24 g Ceq/kWh

Solar PV—43–73 g Ceq/kWh

Hydroelectric—1–34 g Ceq/kWh

Biomass—35–99 g Ceq/kWh

Wind—8–30 g Ceq/kWh

Fthenakis & Kim (2007) Nuclear—16–55 g Ceq/kWh

Solar PV—17–49 g Ceq/kWh

(a) CO2 is carbon dioxide.

3 Conclusion. The sampling of data presented in Table 6–2, Table 6–3, and Table 6–4

4 demonstrates the challenges of any attempt to determine the specific amount of GHG emission 

5 attributable to nuclear energy production sources, as different assumptions and calculation 

6 methods will yield differing results. The differences and complexities in these assumptions and 

7 analyses will further increase when they are used to project future GHG emissions. 

8 Nevertheless, several conclusions can be drawn from the information presented.

9 First, the various studies show a general consensus that nuclear power currently produces 

10 fewer GHG emissions than electrical generation based on fossil fuel. For example, the GHG 

11 emissions from a complete nuclear fuel cycle currently range from 2.5 to 55 grams of carbon 

12 equivalent per Kilowatt hour (g Ceq/kWh), as compared to the use of coal plants 

13 (264 to 1,250 g Ceq/kWh) and natural gas plants (120 to 780 g Ceq/kWh). The studies also give 

14 estimates of GHG emissions from five renewable energy sources based on current technology. 

15 These estimates included solar-photovoltaic (17 to 125 g Ceq/kWh), hydroelectric 
Environmental Impacts of the Uranium Fuel Cycle, 

Waste Management, and Greenhouse Gas Emissions

6-8 

1 (1 to 64.6 g Ceq/kWh), biomass (8.4 to 99 g Ceq/kWh), wind (2.5 to 30 g Ceq/kWh), and tidal 

2 (25 to 50 g Ceq/kWh). The range of these estimates is wide, but the general conclusion is that 

3 current GHG emissions from the nuclear fuel cycle are of the same order of magnitude as from 

4 these renewable energy sources.

5 Second, the studies show no consensus on future relative GHG emissions from nuclear power 

6 and other sources of electricity. There is substantial disagreement among the various authors 

7 about the GHG emissions associated with declining uranium ore concentrations, future uranium 

8 enrichment methods, and other factors, including changes in technology. Similar disagreement 

9 exists about future GHG emissions associated with coal and natural gas for electricity 

10 generation. Even the most conservative studies conclude that the nuclear fuel cycle currently 

11 produces fewer GHG emissions than sources based on fossil fuel and is expected to continue to 

12 do so in the near future. The primary difference between the authors is the projected cross-over 

13 date (the time at which GHG emissions from the nuclear fuel cycle exceed those sources based 

14 on fossil fuel) or whether cross-over will actually occur. 

15 Considering the current estimates and future uncertainties, it appears that GHG emissions 

16 associated with the proposed STP relicensing action are likely to be lower than those 

17 associated with energy sources based on fossil fuel. The staff bases this conclusion on the 

18 following rationale:

19 • As shown in Table 6–2 and Table 6–3, the current estimates of GHG 

20 emissions from the nuclear fuel cycle are far below those for energy sources

21 based on fossil fuel. 

22 • License renewal of a nuclear power plant like STP may involve continued 

23 GHG emissions due to uranium mining, processing, and enrichment, but will 

24 not result in increased GHG emissions associated with plant construction or 

25 decommissioning (as the plant will have to be decommissioned at some point 

26 whether the license is renewed or not).

27 • Few studies predict that nuclear fuel cycle emissions will exceed those of 

28 fossil fuels within a timeframe that includes the STP periods of extended 

29 operation. Several studies suggest that future extraction and enrichment 

30 methods, the potential for higher-grade resource discovery, and technology 

31 improvements could extend this timeframe.

32 With respect to comparison of GHG emissions among the proposed STP license renewal action 

33 and renewable energy sources, it appears likely that there will be future technology 

34 improvements and changes in the type of energy used for mining, processing, and constructing 

35 facilities of all types. Currently, the GHG emissions associated with the nuclear fuel cycle and 

36 renewable energy sources are within the same order of magnitude. Because nuclear fuel 

37 production is the most significant contributor to possible future increases in GHG emissions 

38 from nuclear power—and because most renewable energy sources lack a fuel component—it is 

39 likely that GHG emissions from renewable energy sources would be lower than those 

40 associated with STP at some point during the period of extended operation.

41 The staff also supplies an additional discussion about the contribution of GHG to cumulative air 

42 quality impacts in Section 4.11.2 of this supplemental environmental impact statement (SEIS).
Environmental Impacts of the Uranium Fuel Cycle, 

Waste Management, and Greenhouse Gas Emissions

6-9 

6.3

2 10 CFR 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental Protection 

3 Regulations for Domestic Licensing and Related Regulatory Functions.”

1 References

4 10 CFR 54. Code of Federal Regulations, Title 10, Energy, Part 54, “Requirements for Renewal 

5 of Operating Licenses for Nuclear Power Plants.”

6 [AEA] AEA Technology. 2006. “Carbon Footprint of the Nuclear Fuel Cycle, Briefing Note.” 

7 East Kilbride, UK: British Energy Group. March 2006. Available at 

8 <http://www.british-energy.com/documents/carbon_footprint.pdf> (accessed on April 5, 2012).

9 Andseta S, Thompson MJ, Jarrell JP, Pendergast DR. 1998. CANDU Reactors and 

10 Greenhouse Gas Emissions. Proceedings of the 19th Annual Conference, Canadian Nuclear 

11 Society; 1998 October 18-21; Toronto, Ontario. Available at 

12 <http://www.computare.org/Support%20documents/Publications/Life%20Cycle.htm> (accessed 

13 on April 5, 2012).

14 Dones R. 2007. Critical Note on the Estimation by Storm Van Leeuwen JW and Smith P of the 

15 Energy Uses and Corresponding CO2 Emissions for the Complete Nuclear Energy Chain. 

16 Villigen, Switzerland: Paul Sherer Institute. April 2007. Available at 

17 <http://gabe.web.psi.ch/pdfs/Critical%20note%20GHG%20PSI.pdf> (accessed on 

18 April 5, 2012).

19 Fritsche UR. 2006. Comparison of Greenhouse-Gas Emissions and Abatement Cost of 

20 Nuclear and Alternative Energy Options from a Life-Cycle Perspective. Freiburg, Germany: 

21 Oko-Institut. January 2006. Available at <http://www.oeko.de/oekodoc/315/2006-017-en.pdf> 

22 (accessed on April 5, 2012)

23 Fthenakis VM, Kim HC. 2007. Greenhouse-gas emissions from solar-electric and nuclear 

24 power: A life cycle study. Energy Policy 35(4):2549–2557.

25 [IAEA] International Atomic Energy Agency. 2000. Nuclear Power for Greenhouse Gas 

26 Mitigation under the Kyoto Protocol: The Clean Development Mechanism (CDM). Vienna, 

27 Austria: IAEA. November 2000. Available at 

28 <http://www.iaea.org/Publications/Booklets/GreenhouseGas/greenhousegas.pdf> (accessed on 

29 April 5, 2012).

30 Mortimer N. 1990. World warms to nuclear power. SCRAM Safe Energy Journal

31 Dec 89/Jan 90. Available at <http://www.no2nuclearpower.org.uk/articles/mortimer_se74.php> 

32 (accessed on April 5, 2012).

33 [NEA and OECD] Nuclear Energy Agency and the Organization for Economic Co-operation and 

34 Development. 2002. Nuclear Energy and the Kyoto Protocol. Paris, France: OECD. Available 

35 at <http://www.nea.fr/ndd/reports/2002/nea3808-kyoto.pdf> (accessed on April 5, 2012).

36 [NRC] U.S. Nuclear Regulatory Commission. 1996. Generic Environmental Impact Statement 

37 for License Renewal of Nuclear Plants. NUREG-1437, Volumes 1 and 2, Washington, DC.

38 [NRC] U.S. Nuclear Regulatory Commission. Code Manual for MACCS2: Volume 1, User’s 

39 Guide. Washington, DC. NRC. NUREG/CR–6613. May 1998. ADAMS No. ML063550020.

40 [NRC] U.S. Nuclear Regulatory Commission. 1999. Generic Environmental Impact Statement 

41 for License Renewal of Nuclear Plants, Main Report, “Section 6.3, Transportation, Table 9.1, 

42 Summary of Findings on NEPA Issues for License Renewal of Nuclear Power Plants, Final 

43 Report.” NUREG-1437, Volume 1, Addendum 1, Washington, DC.
Environmental Impacts of the Uranium Fuel Cycle, 

Waste Management, and Greenhouse Gas Emissions

6-10

1 [NRC] U.S. Nuclear Regulatory Commission. 2012. Commission, Memorandum and Order 

2 CLI-12-16, ADAMS No. ML12220A094.

3 [POST] Parliamentary Office of Science and Technology. 2006. Carbon footprint of electricity 

4 generation. Postnote 268. October 2006. Available at 

5 <http://www.parliament.uk/documents/post/postpn268.pdf> (accessed on April 5, 2012).

6 Schneider M. 2000. Climate Change and Nuclear Power. Gland, Switzerland: WWF-World 

7 Wildlife Fund for Nature. April 2000. Available at 

8 <http://assets.panda.org/downloads/fullnuclearreprotwwf.pdf> (accessed on April 5, 2012).

9 Spadaro JV, Langlois L, Hamilton B. 2000. “Greenhouse Gas Emissions of Electricity 

10 Generation Chains: Assessing the Difference.” Vienna, Austria: International Atomic Energy 

11 Agency. Available at 

12 <http://www.iaea.org/Publications/Magazines/Bulletin/Bull422/article4.pdf>.

13 [STPNOC] STP Nuclear Operating (STPNOC). 2010. License Renewal Application, South 

14 Texas Project, Units 1 and 2, Appendix E, Applicant’s Environmental Report, Operating License 

15 Renewal Stage. ADAMS No. ML103010257.

16 Storm van Leeuwen JW, Smith P. 2008. Nuclear Power—The Energy Balance. Chaam, 

17 Netherlands: Ceedata Consultancy. February 2008. Available at <http://www.stormsmith.nl/> 

18 (accessed on April 5, 2012).

19 Weisser D. 2006. A guide to life-cycle greenhouse gas (GHG) emissions from electric supply 

20 technologies. Energy 32(9): 1543–1559. Available at 

21 <http://www.iaea.org/OurWork/ST/NE/Pess/assets/GHG_manuscript_pre-print_

22 versionDanielWeisser.pdf> (accessed on April 5, 2012).
7-1 

1 7.0 ENVIRONMENTAL IMPACTS OF DECOMMISSIONING

2 Environmental impacts from the activities associated with the decommissioning of any reactor 

3 before or at the end of an initial or renewed license are evaluated in Supplement 1 of 

4 NUREG-0586, Final Generic Environmental Impact Statement on Decommissioning of Nuclear 

5 Facilities Regarding the Decommissioning of Nuclear Power Reactors (NRC 2002). The U.S. 

6 Nuclear Regulatory Commission (NRC) staff’s (the staff’s) evaluation of the environmental 

7 impacts of decommissioning—presented in NUREG-0586, Supplement 1—notes a range of 

8 impacts for each environmental issue.

9 Additionally, the incremental environmental impacts associated with decommissioning activities 

10 resulting from continued plant operation during the renewal term are discussed in 

11 NUREG-1437, Generic Environmental Impact Statement for License Renewal of Nuclear Plants 

12 (GEIS) (NRC 1996, 1999). The GEIS includes a determination of whether the analysis of the 

13 environmental issue could be applied to all plants and whether additional mitigation measures 

14 would be warranted. Issues were then assigned a Category 1 or a Category 2 designation. 

15 Section 1.4 of this supplemental environmental impact statement (SEIS) explains the criteria for 

16 Category 1 and Category 2 issues and defines the impact designations of SMALL, MODERATE, 

17 and LARGE. The staff analyzed site-specific issues (Category 2) for South Texas Project (STP) 

18 and assigned them a significance level of SMALL, MODERATE, or LARGE, or not applicable to 

19 STP because of site characteristics or plant features. There are no Category 2 issues related to 

20 decommissioning.

7.1

Table 7–1

21 Decommissioning

22 lists the Category 1 issues in Table B–1 of Title 10 of the Code of Federal 

23 Regulations (CFR) Part 51, Subpart A, Appendix B, that are applicable to STP decommissioning 

24 following the renewal term.

25 Table 7–1. Issues Related to Decommissioning

Issues GEIS Sections Category

Radiation doses 7.3.1; 7.4 1

Waste management 7.3.2; 7.4 1

Air quality 7.3.3; 7.4 1

Water quality 7.3.4; 7.4 1

Ecological resources 7.3.5; 7.4 1

Socioeconomic impacts 7.3.7; 7.4 1

26 Decommissioning would occur whether STP were shut down at the end of its current operating 

27 license or at the end of the period of extended operation. There are no site-specific issues 

28 related to decommissioning.

29 A brief description of the staff’s review and the GEIS conclusions, as codified in Table B-1, 

30 10 CFR Part 51, for each of the issues follows:
Environmental Impacts of Decommissioning

7-2 

1 Radiation Doses. Based on information in the GEIS, the NRC noted that “[d]oses to the public 

2 will be well below applicable regulatory standards regardless of which decommissioning method 

3 is used. Occupational doses would increase no more than 1 person-rem (1 person-mSv) 

4 caused by buildup of long-lived radionuclides during the license renewal term.”

5 Waste Management. Based on information in the GEIS, the NRC noted that 

6 “[d]ecommissioning at the end of a 20-year license renewal period would generate no more 

7 solid wastes than at the end of the current license term. No increase in the quantities of 

8 Class C or greater than Class C wastes would be expected.”

9 Air Quality. Based on information in the GEIS, the NRC noted that “[a]ir quality impacts of 

10 decommissioning are expected to be negligible either at the end of the current operating term or 

11 at the end of the license renewal term.”

12 Water Quality. Based on information in the GEIS, the NRC noted that “[t]he potential for 

13 significant water quality impacts from erosion or spills is no greater whether decommissioning 

14 occurs after a 20-year license renewal period or after the original 40-year operation period, and 

15 measures are readily available to avoid such impacts.” 

16 Ecological Resources. Based on information in the GEIS, the NRC noted that 

17 “[d]ecommissioning after either the initial operating period or after a 20-year license renewal 

18 period is not expected to have any direct ecological impacts.”

Socioeconomic Impacts

23 The staff has not found any new and significant information during its independent review of 

24 South Texas Project Nuclear Operating Company’s (STPNOC’s) Environmental Report (ER) 

25 (STPNOC 2010), the site audit, the scoping process, or its evaluation of other available 

26 information. Therefore, the NRC staff concludes that there are no impacts related to these 

27 issues, beyond those discussed in the GEIS (NRC 1996, 1999). For all of these issues, the 

28 NRC staff concluded in the GEIS that the impacts are SMALL, and additional plant-specific 

29 mitigation measures are not likely to be sufficiently beneficial to be warranted.

19 . Based on information in the GEIS, the NRC noted that 

20 “[d]ecommissioning would have some short-term socioeconomic impacts. The impacts would 

21 not be increased by delaying decommissioning until the end of a 20-year relicense period, but 

22 they might be decreased by population and economic growth.”

7.2

31 10 CFR 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental protection 

32 regulations for domestic licensing and related regulatory functions.”

30 References

33 [NRC] U.S. Nuclear Regulatory Commission. 1996. Generic Environmental Impact Statement 

34 for License Renewal of Nuclear Plants. Washington, DC: NRC. NUREG-1437. May 1996. 

35 ADAMS Nos. ML040690705 and ML040690738.

36 [NRC] U.S. Nuclear Regulatory Commission. 1999. Section 6.3, Transportation, Table 9.1, 

37 Summary of findings on NEPA issues for license renewal of nuclear power plants. In: Generic 

38 Environmental Impact Statement for License Renewal of Nuclear Plants. Washington, DC: 

39 NRC. NUREG-1437, Volume 1, Addendum 1. August 1999. ADAMS No. ML04069720.

40 [NRC] U.S. Nuclear Regulatory Commission. 2002. Final Generic Environmental Impact

41 Statement on Decomissioning of Nuclear Facilities Regarding the Decommissioning of Nuclear 
Environmental Impacts of Decommissioning

7-3 

1 Power Reactors. Washington, DC. NRC. NUREG-0586, Supplement 1. November 2002. 

2 ADAMS No. ML023470304 and ML023500295.

3 [STPNOC] South Texas Plant Nuclear Operating Company. 2010. “South Texas Project, 

4 Applicant’s Environmental Report—Operating License Renewal Stage, South Texas Project

5 Units 1 & 2.” September 2010. ADAMS No. ML103010263. 

8-1 

8-1 

1 8.0 ENVIRONMENTAL IMPACTS OF ALTERNATIVES

2 The National Environmental Policy Act (NEPA) requires the consideration of a range of 

3 reasonable alternatives to the proposed action in an environmental impact statement (EIS). In 

4 this case, the proposed action is whether to issue renewed licenses for South Texas Project 

5 (STP), Units 1 and 2, which will allow the plant to operate for 20 years beyond the current 

6 license expiration dates. A license is just one of many authorizations that an applicant must 

7 obtain in order to operate its nuclear plant. Energy-planning decisionmakers and the owners of 

8 the nuclear power plant ultimately decide if the plant will operate. Economic and environmental 

9 considerations play a primary role in this decision. The U.S. Nuclear Regulatory Commission’s 

10 (NRC’s) responsibility is to ensure the safe operation of nuclear power facilities, not to formulate 

11 energy policy or encourage or discourage the development of alternative power generation (or 

12 replacement power alternatives). 

13 The license renewal process is designed to assure safe operation of the nuclear power plant 

14 during the license renewal term. Under the NRC’s environmental protection regulations in 

15 Title 10, Part 51, of the Code of Federal Regulations (10 CFR Part 51), which implement 

16 Section 102(2) of NEPA, renewal of a nuclear power plant operating license requires the 

17 preparation of an EIS.

18 To support the preparation of these EISs, the NRC prepared the Generic Environmental Impact 

19 Statement for License Renewal of Nuclear Plants (GEIS), NUREG-1437, in 1996. The license 

20 renewal GEIS was prepared to assess the environmental impacts of continued nuclear power 

21 plant operations during the license renewal term. The intent was to determine which 

22 environmental impacts would result in essentially the same impact at all nuclear power plants 

23 and which ones could result in different levels of impacts at different plants and would require a 

24 plant-specific analysis to determine the impacts. For those issues that could not be generically 

25 addressed, the NRC develops a plant-specific supplemental environmental impact statement 

26 (SEIS) to the GEIS.

27 NRC regulations in 10 CFR 51.71(d) for license renewal require that a SEIS do the following: 

28 Consider and weigh the environmental effects of the proposed action [license 

29 renewal]; the environmental impacts of alternatives to the proposed action; and 

30 alternatives available for reducing or avoiding adverse environmental effects.

31 While the GEIS reached generic conclusions regarding many environmental issues associated 

32 with license renewal, it did not determine which alternatives are reasonable or reach 

33 conclusions about site-specific environmental impact levels. As such, the NRC must evaluate 

34 environmental impacts of alternatives on a site-specific basis.

35 As stated in Chapter 1 of this SEIS, alternatives to renewing STPNOC’s operating licenses must 

36 meet the purpose and need for the proposed action. They must “provide an option that allows 

37 for power generation capability beyond the term of a current nuclear power plant operating 

38 license to meet future system generating needs, as such needs may be determined by State, 

39 utility, and, where authorized, Federal (other than NRC) [decisionmakers].”

40 The NRC ultimately makes no decision about which alternative (or the proposed action) to carry 

41 out because that decision falls to the appropriate energy-planning decisionmakers. 
Environmental Impacts of Alternatives

8-2 

1 Comparing the environmental effects of these 

2 alternatives will help the NRC decide if the adverse 

3 environmental impacts of license renewal are great 

4 enough to deny the option of license renewal for 

5 energy-planning decisionmakers 

6 (10 CFR 51.95(c)(4)). If the NRC acts to issue a 

7 renewed license, all of the alternatives, including the 

8 proposed action, will be available to energy-planning 

9 decisionmakers. If NRC decides not to renew the 

10 license (or takes no action at all), then 

11 energy-planning decisionmakers may no longer elect 

12 to continue operating STP and will have to resort to 

13 another alternative—which may or may not be one of 

14 the alternatives considered in this section—to meet 

15 their energy needs now being satisfied by STP.

16 In evaluating alternatives to license renewal, the NRC 

17 considered energy technologies or options currently 

18 in commercial operation, as well as some 

19 technologies not currently in commercial operation 

20 but likely to be commercially available by the time the 

21 current STP operating licenses expire. The current operating licenses for STP, Units 1 and 2, 

22 will expire on August 20, 2027, and December 15, 2028, respectively. The NRC’s analysis 

23 assumed that an alternative must be available (able to be constructed, permitted, and 

24 connected to the grid) by the time the current STP licenses expire.

25 NRC eliminated alternatives that cannot meet future system needs by providing the amounts of 

26 baseload power equivalent to the STP current generating capacity (2,500 megawatts electric 

27 (MWe)) and whose costs or benefits do not justify inclusion in the range of reasonable 

28 alternatives from detailed studies. NRC evaluated the remaining alternatives, which are 

29 discussed in-depth in this section. Each alternative eliminated from detailed study is briefly 

30 discussed, and a basis for its removal is provided at the end of this section. In total, 18 energy 

31 technology options and alternatives to the proposed action were considered (see text box) and 

32 then narrowed to the 5 alternatives considered in Sections 8.1 through 8.5. The no-action 

33 alternative is considered in Section 8.7.

34 The GEIS presents an overview of some energy technologies but does not reach any 

35 conclusions about which alternatives are most appropriate. Since 1996, many energy 

36 technologies have evolved significantly in capability and cost, while regulatory structures have 

37 changed to either promote or impede development of particular alternatives.

38 As a result, the analyses include updated information from the following sources:

39 • Energy Information Administration (EIA), 

40 • other offices within the Department of Energy (DOE), 

41 • U.S. Environmental Protection Agency (EPA), 

42 • Electric Reliability Council of Texas (ERCOT), 

43 • industry sources and publications, and 

44 • information submitted by the applicant in the STP Nuclear Operating 

45 Company’s (STPNOC) Environmental Report (ER). 

Alternatives Evaluated In-Depth:

• new nuclear, 

• natural gas-fired combined-cycle (NGCC), 

• supercritical coal, 

• combination alternative (NGCC, wind, and 

energy efficiency and conservation), and

• purchased power. 

Other Alternatives Considered: 

• offsite nuclear-, gas-, or coal- generation, 

• energy efficiency and conservation, 

• wind power, 

• solar power, 

• hydroelectric power, 

• wave and ocean energy, 

• geothermal power, 

• municipal solid waste, 

• biomass, 

• biofuels, 

• oil-fired power, 

• fuel cells, and 

• delayed retirement.
Environmental Impacts of Alternatives

8-3 

1 The evaluation of each alternative considers the 

2 environmental impacts across several impact 

3 categories: air quality, groundwater use and 

4 quality, surface water use and quality, aquatic 

5 resources, terrestrial resources, human health, 

6 land use, socioeconomics, transportation, 

7 aesthetics, archaeological and historic resources, 

8 environmental justices, and waste management. A 

9 three-level standard of significance—SMALL, 

10 MODERATE, or LARGE—is used to indicate the 

11 intensity of environmental effects for each 

12 alternative undergoing in-depth evaluation. The 

13 order of presentation is not meant to imply 

14 increasing or decreasing level of impact. Nor does 

15 it imply that an energy-planning decisionmaker 

16 would select one or another alternative.

17 For each alternative where it is feasible to do so, 

18 the NRC considers the environmental effects of 

19 locating the alternative at the existing STP site, as 

20 well as at an alternate site. Selecting the existing 

21 plant site allows for the maximum use of existing 

22 transmission and cooling system infrastructures 

23 and minimizes the overall environmental impact.

24 In addition, to ensure that the alternatives analysis was consistent with State or regional energy 

25 policies, the NRC reviewed energy relevant statutes, regulations, and policies. The NRC also 

26 considered the current generation capacity mix and electricity production data within the 

27 ERCOT service area, in which STP, Units 1 and 2, are located. ERCOT is one of eight regional 

28 reliability councils in North America and operates under the reliability and safety standards set 

29 by the North American Electric Reliability Council (STPNOC 2010a). ERCOT is the 

30 independent system operator for the electric grid for most of Texas and manages the flow of 

31 electric power to approximately 23 million Texas customers, representing 85 percent of the 

32 State’s electric load and 75 percent of the State’s land area. ERCOT is unique because it is 

33 located entirely within the boundaries of the State of Texas. As such, the NRC considered the 

34 current generation capacity mix and electricity production data within the ERCOT service area in 

35 the evaluation of reasonable alternatives. In 2010, electric generators in ERCOT had an 

36 installed generating capacity of approximately 84,400 MWe. This capacity included units fueled 

37 by natural gas (57 percent), coal (23 percent), wind (12 percent), nuclear (6 percent), and other 

38 sources (2 percent). In 2010, the electric generators in ERCOT provided approximately 

39 319 million megawatt-hours of electricity. Electricity produced was dominated by coal 

40 (40 percent) followed by natural gas (38 percent), nuclear (13 percent), wind (8 percent), and 

41 other sources (1 percent) (ERCOT 2011a).

42 Sections 8.1 through 8.5 describe the environmental impacts of alternatives to license renewal. 

43 These alternatives include a new nuclear generation option in Section 8.1; a new NGCC in 

44 Section 8.2; a new coal-fired plant in Section 8.3; a combination alternative of NGCC, wind, and 

45 energy conservation and efficiency in Section 8.4; and purchased power in Section 8.5. In 

46 Section 8.6, alternatives considered but eliminated from detailed study are briefly discussed. 

47 Finally, the environmental effects that may occur if the NRC takes no action and does not issue 

48 renewed licenses for STP are described in Section 8.7. Section 8.8 summarizes, in detail, the 

49 impacts of each of the alternatives considered.

Energy Outlook

Each year, the EIA—part of the DOE—issues its 

updated Annual Energy Outlook (AEO). 

AEO 2011, affirms that natural gas, renewable, 

and coal are likely to fuel most new electrical 

capacity through 2035, with some growth in 

nuclear capacity (EIA 2011a), although all 

projections are subject to future developments in 

fuel price, electrical demand, and regulatory 

changes.

“Natural gas-fired plants account for 60 percent

of capacity additions between 2010 and 2035 in 

the AEO2011 Reference case, compared with 

25 percent for renewables, 11 percent for coalfired plants, and 3 percent for nuclear. 

Escalating construction costs have the largest 

impact on capital-intensive technologies, 

including nuclear, coal, and renewables. 

However, Federal tax incentives, State energy 

programs, and rising prices for fossil fuels 

increase the competitiveness of renewable and 

nuclear capacity. In contrast, uncertainty about 

future limits on GHG [greenhouse-gas] 

emissions and other possible environmental 

regulations reduces the competitiveness of coalfired plants....” (EIA 2011a).
Environmental Impacts of Alternatives

8-4 

8.1

2 In this section, the NRC staff evaluates the environmental impacts of a new nuclear generation 

3 option at the STP site.

1 New Nuclear Generation

4 The NRC considers the construction of two new nuclear plants to be a reasonable alternative to 

5 STP license renewal for Units 1 and 2 because nuclear generation currently provides baseload 

6 power in the ERCOT region, ERCOT expects additional nuclear generation in the future, and 

7 the technology to provide nuclear generation is readily available (ERCOT 2011a). In addition, 

8 on September 30, 2007, STPNOC submitted combined license (COL) applications to construct 

9 and operate two new advanced boiling water reactor (ABWR) nuclear plants (Units 3 and 4) on 

10 the STP site (NRC 2011). In its ER for Units 3 and 4, STPNOC’s schedule included 5 years 

11 from when NRC issues its licenses to when commercial operations could begin 

12 (STPNOC 2010b). Therefore, there is sufficient time for STPNOC to prepare and submit an 

13 application and build and operate two new nuclear units before the licenses for Units 1 and 2 

14 expire in 2027 and 2028, respectively. This section presents the environmental impacts of the 

15 new nuclear generation alternative, which includes constructing and operating two new nuclear 

16 plants at the STP site.

17 In evaluating the new nuclear alternative, based on best available information, the NRC 

18 presumed that new reactors would be installed on the STP site, allowing for the maximum use 

19 of existing ancillary facilities such as the transmission and cooling systems. The NRC further 

20 presumed that the new reactors would be two ABWR reactors similar to what the NRC analyzed 

21 in its environmental analysis for Units 3 and 4 in its final EIS (NRC 2011). As of 

22 September 2012, NRC is continuing to review the STP application for Units 3 and 4. While the 

23 licenses have not been granted as of September 2012, the NRC staff is using the results from 

24 its final EIS for Units 3 and 4 because it provides a site-specific analysis of two new nuclear 

25 plants at the STP site.

26 For the purpose of this analysis, each of the two ABWR reactors would have a net electrical 

27 output of approximately 1,300 MWe, which is slightly more than the generating capacity 

28 (2,500-MWe capacity) of STP, Units 1 and 2 (STPNOC 2010a). STPNOC (2010a) estimated 

29 that the power block and ancillary facilities (excluding the cooling-water system) for the new 

30 reactors would require approximately 540 ac (219 ha) and that sufficient contiguous acreage 

31 was available on the STP site. Because the heat-rejection demands are similar for Units 1 

32 and 2 and proposed Units 3 and 4, the NRC estimated that the existing cooling system—

33 including the existing intake and discharge structures on the main cooling reservoir (MCR) and 

34 the Colorado River—would meet the heat-rejection demands of the two new reactors without 

35 any modifications. In STPNOC’s ER for Units 3 and 4, STPNOC assumed minor modifications 

36 would be required to increase operations from two units to four units at the STP site. For the 

37 purposes of this analysis, the two new reactors would replace Units 1 and 2 rather than add two 

38 new units to the site; therefore, it is unlikely that modification would be required. Construction 

39 materials would be delivered via rail, truck, or barge. To accommodate such shipments, 

40 STPNOC would need to dredge near the current barge slip, and the rail spur would require 

41 upgrades (STPNOC 2010b).

42 NRC assumed that construction of two new nuclear units at the STP site would generally follow 

43 the same timeframe as that described in STPNOC’s ER for the construction of Units 3 and 4. 

44 This schedule included 12 months for site preparation, 45 months after NRC issues the licenses 

45 to complete construction and fuel loading, 6 months from fuel loading to initial power generation 

46 for Unit 3, and an additional 12 months for Unit 4 (STPNOC 2010b).
Environmental Impacts of Alternatives

8-5 

1 The NRC also considered the installation of multiple small and modular reactors at the STP site 

2 as an alternative to renewing the licenses for STP, Units 1 and 2. NRC established the 

3 Advanced Reactor Program in the Office of New Reactors due to considerable interest in small 

4 and modular reactors along with anticipated license applications by vendors. As of 

5 September 2012 (based on best available information), NRC has not received any applications. 

6 Because there are no applications to construct and operate small modular reactors on a 

7 commercial scale, this analysis focused on nuclear generation by larger nuclear units.

8 8.1.1 Air Quality

9 As discussed in Section 2.2.2.1, the STP site is located in central Matagorda County, Texas, at 

10 the southern edge of the Metropolitan Houston-Galveston Intrastate Air Quality Control Region 

11 (40 CFR 81.38). The Corpus Christi-Victoria Intrastate Air Quality Control Region 

12 (40 CFR 81.136) lies immediately south and west of Matagorda County. EPA has designated 

13 all of the counties in these Air Quality Control Regions adjacent to the STP site as in compliance 

14 with the National Ambient Air Quality Standards (40 CFR 81.344) except Brazoria County to the 

15 north; Brazoria County is classified Nonattainment/Severe relative to the 8-hour ozone standard 

16 (EPA 2011b).

17 Construction activities would cause some localized temporary air effects as a result of 

18 equipment emissions and fugitive dust from the operation of the earth-moving and 

19 material-handling equipment. Emissions from workers’ vehicles and motorized construction 

20 equipment exhaust would be temporary. Construction crews would use dust-control practices to 

21 control and reduce fugitive dust, as proposed for Units 3 and 4 (STPNOC 2010b), and because 

22 §111.145 of the Texas Commission for Environmental Quality’s (TCEQ) regulations require dust 

23 suppression control during the construction of facilities and parking lots.

24 During operations, two new nuclear plants would have similar air emissions to those of existing 

25 STP, Units 1 and 2, and those expected from proposed Units 3 and 4; air emissions would be 

26 primarily from backup diesel generators. Because air emissions would be similar for the new 

27 nuclear plants, the NRC expects similar air permitting conditions and regulatory requirements as 

28 that for Units 3 and 4. In STPNOC’s ER for Units 3 and 4, STPNOC stated that “[a]ir emissions 

29 sources would be managed in accordance with Federal, Texas, and local air quality control laws 

30 and regulations.” Permitting would likely include a prevention of significant deterioration (PSD) 

31 review and an operating permit from TCEQ.

32 STPNOC estimated air emissions during the operation of Units 3 and 4 as part of its COL 

33 application (NRC 2011; STPNOC 2010b). The largest stationary sources of emissions would be 

34 from three standby diesel generators and a single combustion turbine generator, each of which 

35 would be operated about 4 hours per month. Table 8–1 lists the expected annual emissions 

36 from these sources. NRC assumed that there would be similar air emissions from two new 

37 nuclear units.

38
Environmental Impacts of Alternatives

8-6 

1 Table 8–1. Expected Annual Emissions from the Largest 

2 Stationary Sources of Emissions

Diesel Generators (lb/yr) Combustion Turbine (lb/yr)

Particulates 2,500 44

Sulfur Oxides 9,200 3,800

Carbon Monoxide 9,200 1,800

Hydrocarbons 6,100 120

Nitrogen Oxides 57,900 4,000

Source: STPNOC 2010b

3 The operation of nuclear power plants involves the emission of some greenhouse gases, 

4 primarily carbon dioxide. NRC (2011) estimated that the total carbon footprint for actual plant 

5 operations of Units 3 and 4 for 40 years is on the order of 650,000 metric tons (MT)

6 (720,000 tons) of carbon dioxide equivalent (an emissions rate of about 16,000 MT

7 (18,000 tons) annually, averaged over the period of operation). Periodic testing of diesel 

8 generators and other activities during plant operations accounts for about 60 percent of the 

9 total, or about 190,000 MT (210,000 tons) for each unit. Workforce transportation accounts for 

10 the most of the remaining 40 percent, or about 130,000 MT (140,000 tons) for each unit. 

11 NRC (2011) based these carbon footprint estimates on information included in Appendix I of the 

12 final EIS and emissions data contained in the ER for Units 3 and 4 (STPNOC 2010b). 

13 Equipment maintenance and measures taken to mitigate transportation impacts, such as 

14 properly maintained asphalt or concrete roads and appropriate speed limits (STPNOC 2010b), 

15 would also reduce carbon dioxide emissions, while reducing other emissions. For example, 

16 STPNOC (2010b) states that fugitive dust generated by the commuting workforce would be 

17 minimized by properly maintaining hard-surfaced access roads and setting appropriate speed 

18 limits.

19 Subpart P of 40 CFR Part 51 contains the visibility protection regulatory requirements, including 

20 the review of new sources to be constructed in attainment or unclassified areas and that may 

21 affect visibility in any Federal Class I area. If a new nuclear plant were located close to a 

22 mandatory Class I area, additional air pollution control requirements may be required. As noted 

23 in Section 2.2.2.1, there are no Mandatory Class I Federal areas within 100 mi (161 km) of the 

24 STP site where visibility is an important value.

25 Because construction and operations of two new nuclear units at the STP site would not 

26 noticeably alter air quality, air quality impacts would be SMALL.

27 8.1.2 Surface Water Resources

28 The NRC presumes that two new nuclear units would be designed to maximize use of existing 

29 facilities, including the existing intake and discharge structures on the MCR and the Colorado 

30 River. STPNOC did not propose using any surface water during the construction of Units 3 

31 and 4 (NRC 2011); therefore, NRC expects that none would be used during construction for the 

32 new nuclear alternative.

33 Impacts to surface water quality could result from dredging activities in the Colorado River near 

34 the reservoir makeup pumping facility (RMPF) and the barge slip. Dredging can disturb 

35 sediments and potentially increase turbidity near and downstream of the dredged site. The 

36 NRC staff (NRC 2011) determined that the hydrological alterations resulting from site 

37 development would be localized and temporary. Permits and certifications from the U.S. Army 
Environmental Impacts of Alternatives

8-7 

1 Corps of Engineers (USACE) and other agencies would require the implementation of best 

2 management practices (BMPs) to minimize impacts.

3 Runoff from construction areas would be controlled under a State-issued Texas Pollutant 

4 Discharge Elimination System (TPDES) general permit that would require implementation of a 

5 stormwater pollution prevention plan and associated BMPs to prevent or significantly mitigate 

6 soil erosion and contamination of stormwater runoff from construction activities. Runoff from 

7 construction areas would be limited to the duration of the construction.

8 During normal operations, STPNOC would intermittently withdraw and discharge water from and 

9 to the Colorado River to maintain the water quality and quantity in the MCR (NRC 2011). This 

10 would continue to occur in accordance with STPNOC’s existing water rights and a new or 

11 revised State-issued TPDES permit, respectively, under this alternative. Water use would be 

12 similar to that of Units 1 and 2. The NRC staff (NRC 2011) estimated current water use for 

13 Units 1 and 2 during normal operations to be 3 percent of Texas Water Development Board 

14 (TWDB)-estimated Region K water supplies in 2010 (TWDB 2007). Therefore, the impact on 

15 surface water use in the Colorado River basin would be minimal.

16 In consideration of the information above, the impacts on surface water use and quality from 

17 construction and operations under the new nuclear generation alternative would be SMALL.

18 8.1.3 Groundwater Resources

19 The NRC presumes that the two new nuclear units would use existing ancillary facilities at the 

20 STP site, including use of the onsite groundwater production wells. To build Units 3 and 4, 

21 STPNOC (2010b) proposed withdrawing groundwater from the Deep Aquifer during 

22 construction. The NRC staff (NRC 2011) determined that STPNOC’s projected drawdown 

23 during building activities and the current presence of a sufficient confining head would maintain 

24 the Deep Aquifer as a confined aquifer. For construction of the new nuclear units under this 

25 alternative, it is assumed that STPNOC’s existing wells would be used to supply the relatively 

26 small amounts of water (i.e., up to 491 gpm (1,860 L/min)) required for potable and sanitary 

27 uses, concrete production, dust suppression and soil compaction, and other uses during 

28 construction of the new units (NRC 2011).

29 Excavation for the new reactor foundations could extend to depths of approximately 70 ft (21 m) 

30 below ground surface (BGS), and dewatering of the Upper and Lower Shallow Chicot aquifers 

31 would be required. However, slurry walls and wells were proposed for use to minimize potential 

32 adverse effects from dewatering both on site and off site (NRC 2011). Further, application of 

33 BMPs in accordance with a State-issued National Pollutant Discharge Elimination System

34 (NPDES) general permit, including appropriate waste management and spill prevention 

35 practices, would prevent or minimize any groundwater quality impacts during construction.

36 During operations of Units 3 and 4, STPNOC proposed to use groundwater for power block 

37 operational uses, fire protection systems, and potable and sanitary systems, and to use the 

38 existing onsite groundwater production wells at STP. However, one or more additional wells 

39 could also be installed to decrease pumping rates at existing wells and to better distribute 

40 drawdown impacts in the Deep Aquifer and ensure sufficient withdrawal capacity under 

41 STPNOC’s existing groundwater permit (NRC 2011). Groundwater use for operation of the two 

42 replacement units was presumed to be somewhat higher than for existing STP, Units 1 and 2, 

43 but well within the groundwater operating permit held by STPNOC. The groundwater operating 

44 permit issued by the Coast Plains Groundwater Conservation District (see Section 2.1.7.2) is for 

45 approximately 1,860 gpm (7,040 L/min); STP, Units 1 and 2, use approximately 768 gpm 

46 (2,910 L/min) of groundwater; and the new units would require approximately 975 gpm 

47 (3,690 L/min) under normal operating conditions (NRC 2011). The NRC concludes that 
Environmental Impacts of Alternatives

8-8 

1 groundwater use and quality impacts are likely to be similar to those observed for STP, Units 1 

2 and 2.

3 Based on this information, the overall impact on groundwater use and quality from construction 

4 and operations under the new nuclear generation alternative would be SMALL.

5 8.1.4 Aquatic Ecology 

6 The NRC presumed that two new nuclear units would be designed to maximize use of existing 

7 facilities, including the existing intake and discharge structures on the MCR and the Colorado 

8 River.

9 Construction activities for two new reactors (such as construction of heavy haul roads and the 

10 power blocks) could affect drainage areas or other onsite aquatic features due to site runoff. 

11 NRC assumed that STPNOC would install temporary and permanent erosion and sediment 

12 control measures to minimize the flow of disturbed soils into ditches and wetlands. Such BMPs 

13 would likely be described in a Texas Pollutant Discharge Elimination System (TPDES) general 

14 permit relating to stormwater discharges for construction activities.

15 To bring new materials to the site, NRC assumed construction crews would dredge near the 

16 barge slip on the Colorado River to transport some materials using barges, which are activities 

17 that STPNOC (2010b) proposed for the construction of Units 3 and 4. Permits and certifications 

18 from the USACE and other agencies would require the implementation of BMPs to minimize 

19 impacts. NRC (2011) determined that such activities would be temporary and unlikely to cause 

20 noticeable impacts to aquatic resources.

21 Plant operators would withdraw water from the Colorado River to maintain the proper water 

22 quality and quantity in the MCR during operations of two new ABWR units. Aquatic organisms 

23 would be impinged and entrained as water is drawn through the RMPF. Biota most vulnerable 

24 to entrainment and impingement would be the same as those described in Section 4.5 during 

25 the period of continued operations for Units 1 and 2. The low approach velocity at the RMPF 

26 (less than or equal to approximately 0.5 ft/s), the use of a pond-based heat-dissipation cooling 

27 system, the population status of biota most likely to be impinged and entrained, and the 

28 reproductive potential of fish and shellfish most vulnerable to impingement and entrainment 

29 would result in minimal adverse impacts to the aquatic ecosystem in the Colorado River near 

30 STP.

31 Plant operators would discharge water from the MCR to the Colorado River to maintain water 

32 quality within the MCR. Discharge impacts would be similar to those described in Section 4.5 

33 for continued operations of STP, Units 1 and 2. Discharges are unlikely to noticeably impact 

34 aquatic resources near STP for the following reasons:

35 • STPNOC’s TPDES permit would limit the amount and timing of discharges. 

36 • Modeling studies indicate that mobile aquatic species could avoid the thermal 

37 plume by swimming at a lower depth or different side of the river (NRC 2011). 

38 • Species or life-stages that are less mobile organisms would not be able to 

39 swim away to avoid the thermal plume, such as eggs, larvae, and mollusks. 

40 However, most species observed in this area generally have high fecundity, 

41 and the number of organisms lost would be insignificant compared to their 

42 population in the lower Colorado River. 
Environmental Impacts of Alternatives

8-9 

1 • Cooling water would not be regularly discharged into the Colorado River 

2 because STP uses a cooling pond-based heat-dissipation system that reuses 

3 water from the MCR.

4 The NRC staff determined that the impacts to aquatic resources on the STP site and in the 

5 Colorado River would be SMALL because modifications on site and to the river, such as 

6 dredging, would be temporary, and impingement, entrainment, and heat shock would not 

7 noticeably impact aquatic resources.

8 8.1.5 Terrestrial Ecology

9 STPNOC (2010a) estimated that the power block and ancillary facilities (excluding the 

10 cooling-water system) for the new reactors would require approximately 540 ac (219 ha). 

11 Construction activities, such as building the heavy haul road and new facilities, would 

12 permanently convert approximately 300 ac (121 ha) (STPNOC 2010b). Construction would 

13 likely affect a variety of habitats and land uses, including industrial land (buildings, parking 

14 areas, and mowed-maintained fields), drainage ditches, scattered small palustrine wetlands, 

15 scrub-shrub habitat, and mixed grassland habitat where abandoned farm lands previously 

16 existed prior to construction of Units 1 and 2 (NRC 2011; STPNOC 2010b). Most of these areas 

17 have been mildly to extensively disturbed during the construction and operations of Units 1 

18 and 2 and other human activities. After the completion of the new units, plant operators would 

19 likely grade, landscape, and replant the areas used for temporary building support 

20 (STPNOC 2010b). The majority of permanently affected areas would be maintained land (e.g., 

21 mowed) or other industrial areas. NRC (2011) determined that the change in habitat availability 

22 would unlikely increase fragmentation of onsite habitats available for wildlife. STPNOC would 

23 likely implement BMPs to minimize impacts to wetlands. STPNOC would be required to comply 

24 with the USACE 404 permits (NRC 2011).

25 Construction activities could also adversely affect onsite wildlife through noise, increased light 

26 pollution, and increased traffic. However, NRC (2011) determined that these impacts would be 

27 temporary and minor.

28 STPNOC (2010b) did not observe Federally or State-listed threatened or endangered species, 

29 critical habitat, or suitable habitats in the proposed disturbance area for Units 3 and 4. 

30 NRC (2011) determined that the impacts to special status species from the construction and 

31 operation of Units 3 and 4 would be negligible.

32 Because many construction-related impacts would be temporary, and because the majority of 

33 long-term construction impacts would occur within previously disturbed areas, impacts on 

34 terrestrial resources would be SMALL.

35 8.1.6 Human Health

36 The human health effects from two new nuclear power plants would be similar to those of the 

37 existing STP, Units 1 and 2, and the proposed Units 3 and 4 (NRC 2011). Human health issues 

38 related to construction would be equivalent to those associated with the construction of any 

39 major complex industrial facility and would be controlled to acceptable levels through the 

40 application of BMPs and STPNOC’s compliance with Federal and State worker protection 

41 regulations. Human health impacts from operation of the new nuclear reactors would be 

42 equivalent to those associated with continued operation of the existing reactors and the 

43 proposed Units 3 and 4 (NRC 2011).

44 Both continuous and intermittent noise impacts can be expected at offsite locations, including at 

45 the closest residences. However, confining noise-producing activities to core hours of the day 
Environmental Impacts of Alternatives

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1 (7:00 a.m. to 6:00 p.m.) and notifying potentially affected parties beforehand of such events 

2 would control noise impacts to acceptable levels. Noise impacts would be of short duration and 

3 would be SMALL.

4 Based on the above information, human health impacts for the construction and operation of 

5 two new nuclear units would be SMALL.

6 8.1.7 Land Use

7 The GEIS generically evaluates the impacts of constructing and operating various replacement 

8 power plant alternatives on land use, both on and off each plant site. The analysis of land use 

9 impacts focuses on the amount of land area that would be affected by the construction and 

10 operation of a new nuclear power plant at the STP site.

11 STPNOC (2010a) estimated that the power block and ancillary facilities (excluding the 

12 cooling-water system) for the two new reactors would require approximately 540 ac (219 ha) 

13 and that sufficient contiguous acreage was available on the STP site. A sufficient amount of 

14 land is available on site, and most of the area is already in industrial use. Therefore, onsite land 

15 use impacts from the construction and operation of two new reactors at the STP site would be 

16 SMALL.

17 The amount of land required to mine uranium and fabricate nuclear fuel to support the new 

18 nuclear alternative would be similar to the amount of land required to support STP, Units 1 

19 and 2, although an additional amount of land would be required to support uranium fuel 

20 requirements during the license renewal term. According to GEIS estimates, approximately 

21 2,560 ac (1,036 ha) would be needed for the mining and processing of uranium fuel during the 

22 operating life of the new nuclear plant. Overall, offsite land use impacts from two new nuclear 

23 reactors would be SMALL.

24 8.1.8 Socioeconomics

25 Socioeconomic impacts are defined in terms of changes to the demographic and economic 

26 characteristics and social conditions of a region. For example, the number of jobs created by 

27 the construction and operation of a power plant could affect regional employment, income, and 

28 expenditures.

29 Two types of jobs would be created by this alternative: (1) construction jobs, which are 

30 transient, short in duration, and less likely to have a long-term socioeconomic impact; and 

31 (2) power plant operation jobs, which have the greater potential for permanent, long-term 

32 socioeconomic impacts. Workforce requirements for the construction and operation of the new 

33 nuclear generation alternative were evaluated to measure their possible effects on current 

34 socioeconomic conditions. 

35 STPNOC estimated a construction workforce of up to 5,950 (maximum) workers would be 

36 required to build Units 3 and 4 at the STP site (STPNOC 2010b). The relative economic 

37 impacts of this many workers on the local economy and tax base would vary, with the greatest 

38 impacts occurring in the communities where the majority of construction workers would reside 

39 and spend their income. As a result, local communities could experience a short-term economic 

40 “boom” from increased tax revenue and income generated by construction expenditures and the 

41 increased demand for temporary (rental) housing and business services. Some construction 

42 workers could relocate to Matagorda and surrounding counties in order to be closer to the 

43 construction work site. However, given the proximity of STP to the Houston metropolitan area, 

44 many construction workers could commute to the STP site, thereby lessening the need for 
Environmental Impacts of Alternatives

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1 additional rental housing near STP. After completing the installation of the two new reactor 

2 units, local communities could experience a return to pre-construction economic conditions. 

3 Based on this information, and given the magnitude of the estimated number of workers, 

4 socioeconomic impacts during construction in communities near the STP site could range from 

5 SMALL to LARGE.

6 STPNOC also estimated that STP, Units 3 and 4, would require 733 operations workers and an 

7 additional 1,100 workers during refueling outages (STPNOC 2010b). The number of operation 

8 workers would include some of the 1,378 workers from STP, Units 1 and 2. Socioeconomic 

9 impacts during operations could range from SMALL to MODERATE as the STP site transitions 

10 to the new reactor units. The potential reduction in overall employment at STP could affect 

11 property tax revenue and income in local communities and businesses. In addition, the 

12 permanent housing market could also experience increased vacancies and decreased prices if 

13 operations workers and their families move out of the region. 

14 8.1.9 Transportation

15 Transportation impacts associated with the construction and operation of a new two-unit nuclear 

16 power plant would consist of commuting workers and truck deliveries of construction materials

17 and equipment to the power plant site. During periods of peak construction activity, up to 

18 5,950 workers could be commuting daily to the STP site (STPNOC 2010b). Workers 

19 commuting to the STP site would primarily use two-lane roads. The volume of traffic on these 

20 roads, and especially Farm-to-Market (FM) 521, would increase substantially. In addition to 

21 commuting workers, trucks would be transporting construction materials and equipment to the 

22 worksite, further increasing the amount of traffic on local roads. The increase in vehicular traffic 

23 would peak during shift changes, resulting in temporary levels of service impacts and delays at 

24 intersections. Some power plant components and materials could also be delivered by train or 

25 barge (STPNOC 2010a). Train deliveries could cause additional traffic delays at railroad 

26 crossings. Based on this information, traffic-related transportation impacts during construction

27 could range from MODERATE to LARGE. 

28 Traffic-related transportation impacts would be greatly reduced after completing the installation 

29 of the two new reactor units. Transportation impacts would include daily commuting by the 

30 operating workforce, equipment and materials deliveries, and the removal of commercial waste 

31 material to offsite disposal or recycling facilities by truck. During reactor operations, the 

32 estimated number of operations workers commuting to and from STP would be 733 workers 

33 (STPNOC 2010b). Traffic-related transportation impacts would be less than current operations 

34 because the new units would employ approximately half as many workers as STP, Units 1 

35 and 2. However, overall transportation impacts (related to plant operating workers and potential 

36 Units 1 and 2 decommissioning workers) would range from SMALL to MODERATE during 

37 power plant operations.

38 8.1.10 Aesthetics

39 The analysis of aesthetic impacts focuses on the degree of contrast between the new nuclear 

40 alternative and the surrounding landscape and the visibility of the new power plant. The new 

41 power block would look very similar to the STP, Units 1 and 2, power block.

42 During construction, all of the clearing and excavation would occur on the STP site. These 

43 activities may be visible from offsite roads, particularly FM 521. Since the STP site already 

44 appears industrial, construction of the new units would appear similar to onsite activities during 

45 refueling outages.
Environmental Impacts of Alternatives

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1 During reactor operations, the visual appearance of the STP site would not change since the 

2 power block for the new nuclear reactors would look virtually identical to the existing STP, 

3 Units 1 and 2, power block. Adding two new reactor units would increase the overall size of the 

4 existing STP facility if STP, Units 1 and 2, remained. Given the industrial appearance of the 

5 STP site and the similarity of the new units to the existing units, the new reactor units would 

6 blend in with the surroundings. In addition, the amount of noise generated during reactor 

7 operations would be the same as those generated during STP, Units 1 and 2, operations, which 

8 consists predominantly of the noise from routine industrial processes and communications. In 

9 general, aesthetic changes would be limited to the immediate vicinity of the STP site, and any 

10 impacts would be SMALL.

11 8.1.11 Historic and Archaeological Resources

12 Cultural resources are the indications of human occupation and use of the landscape, as 

13 defined and protected by a series of Federal laws, regulations, and guidelines. Prehistoric 

14 resources are physical remains of human activities that predate written records; they generally 

15 consist of artifacts that may alone or collectively yield information about the past. Historic 

16 resources consist of physical remains that postdate the emergence of written records; in the 

17 U.S., they are architectural structures or districts, archaeological objects, and archaeological 

18 features dating from 1492 and later. Ordinarily, sites less than 50 years old are not considered 

19 historic, but exceptions can be made for such properties if they are of particular importance, 

20 such as structures associated with the development of nuclear power (e.g., Shippingport Atomic 

21 Power Station) or Cold War themes. American Indian resources are sites, areas, and materials 

22 important to American Indians for religious or heritage reasons. Such resources may include 

23 geographic features, plants, animals, cemeteries, battlefields, trails, and environmental features. 

24 The cultural resource analysis encompassed the power plant site and adjacent areas that could 

25 potentially be disturbed by the construction and operation of replacement plant alternatives. 

26 The potential for historic and archaeological resources can vary greatly depending on the 

27 location of the proposed site. To consider a project’s effects on historic and archaeological 

28 resources, any affected areas would need to be surveyed to identify and record historic and 

29 archaeological resources, identify cultural resources (e.g., traditional cultural properties), and 

30 develop possible mitigation measures to address any adverse effects from ground-disturbing 

31 activities.

32 As described in Section 2.2.10, much of the STP site has been previously disturbed by the 

33 construction of STP, Units 1 and 2. In addition, in preparation for the COL application for 

34 Units 3 and 4, STPNOC conducted a cultural resources assessment of the STP site. STPNOC 

35 reviewed existing information for the STP site and the area within a 10-mi (16-km) radius. 

36 STPNOC concluded that any cultural resource sites that may have existed on site would no 

37 longer retain their integrity because the area was heavily disturbed during the construction of 

38 Units 1 and 2 (STPNOC 2010b). In December 2006, STPNOC reported these findings to the 

39 SHPO at the Texas Historical Commission. The SHPO concurred that there would be no 

40 impacts to historic properties in January 2007 (STPNOC 2006; THC 2007).

41 There is a low potential for cultural resources to be located in previously undisturbed portions of 

42 the STP site. However, if the new nuclear units were to be sited within undisturbed areas or 

43 within areas of known cultural sensitivity (historic grave site located on the property and 

44 described in Section 2.2.10), these areas would need to be surveyed by a professional 

45 archaeologist to identify and develop possible mitigation measures to address any adverse 

46 effects from project activities. NRC assumes STPNOC would follow similar procedures to those 

47 described in the final EIS for STP, Units 3 and 4, if any historic or cultural resources were 

48 discovered during ground-disturbing activities associated with building the new units 
Environmental Impacts of Alternatives

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1 (NRC 2011). In the final EIS for STP, Units 3 and 4, the staff concludes that the cumulative 

2 impacts to historic and archaeological resource would be SMALL.

3 The NRC staff determined that the impact of new nuclear plants at the STP site on historic and 

4 archaeological resources would be SMALL for the following reasons:

5 • NRC (2011) and STPNOC (2010a, 2010b) did not identify any cultural 

6 resources that could be affected by Units 3 and 4. 

7 • The SHPO determined that construction for Units 3 and 4 would not affect 

8 cultural and historic resources. 

9 • STPNOC has established environmental compliance procedures for new 

10 ground-disturbing activities.

11 8.1.12 Environmental Justice

12 The environmental justice impact analysis evaluates the potential for disproportionately high and 

13 adverse human health and environmental effects on minority and low-income populations that 

14 could result from the construction and operation of a new power plant. Adverse health effects 

15 are measured in terms of the risk and rate of fatal or nonfatal adverse impacts on human health. 

16 Disproportionately high and adverse human health effects occur when the risk or rate of 

17 exposure to an environmental hazard for a minority or low-income population is significant and 

18 exceeds the risk or exposure rate for the general population or for another appropriate 

19 comparison group. Disproportionately high environmental effects refer to impacts or risk of 

20 impact on the natural or physical environment in a minority or low-income community that are 

21 significant and appreciably exceed the environmental impact on the larger community. Such 

22 effects may include biological, cultural, economic, or social impacts. Some of these potential 

23 effects have been identified in resource areas discussed in this SEIS. For example, increased 

24 demand for rental housing during power plant construction could disproportionately affect 

25 low-income populations. Minority and low-income populations are subsets of the general public 

26 living near the STP site, and all are exposed to the same hazards generated from constructing 

27 and operating two new nuclear plants. Section 4.9.7, “Environmental Justice,” presents 

28 demographic information about minority and low-income populations residing in the vicinity of 

29 the STP site. 

30 Potential impacts to minority and low-income populations from the construction and operation of 

31 a new nuclear power plant at the STP site would mostly consist of environmental and 

32 socioeconomic effects (e.g., noise, dust, traffic, employment, and housing impacts). Noise and 

33 dust impacts during construction would be short-term and primarily limited to onsite activities. 

34 Minority and low-income populations residing along site access roads would be directly affected 

35 by increased commuter vehicle and truck traffic. However, because of the temporary nature of 

36 construction, these effects would only occur at certain hours of the day and are unlikely to be 

37 high and adverse. Increased demand for rental housing during construction could also affect 

38 low-income populations living near STP. However, given the proximity of STP to the Houston 

39 metropolitan area, many construction workers could commute to the STP site, thereby lessening 

40 the need for additional rental housing.

41 Based on this information, and the analysis of human health and environmental impacts 

42 presented in this SEIS, the construction and operation of a new nuclear power plant would not 

43 have disproportionately high and adverse human health and environmental effects on minority 

44 and low-income populations residing in the vicinity of the STP site. 
Environmental Impacts of Alternatives

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1 8.1.13 Waste Management

2 During the construction stage of the new nuclear plants, land clearing and other construction 

3 activities would generate waste that could be recycled, disposed of on site, or shipped to an 

4 offsite waste disposal facility. Because the new nuclear plants would be constructed on the 

5 previously disturbed STP site, the amounts of waste produced during land clearing would be 

6 reduced. 

7 During the operational stage, normal plant operations, routine plant maintenance, and cleaning 

8 activities would generate nonradioactive waste as well as mixed waste, low-level waste, and 

9 high-level waste. Quantities of nonradioactive waste (discussed in Section 2.3.1 of this SEIS) 

10 and radioactive waste (discussed in Section 6.1 of this SEIS) generated by Units 1 and 2 would 

11 be comparable to that generated by the new nuclear plants.

12 According to the GEIS (NRC 1996), the generation and management of solid nonradioactive 

13 and radioactive waste during the period of renewed licenses are not expected to result in 

14 significant environmental impacts. Two new nuclear plants would generate waste streams 

15 similar to the two existing nuclear plants. Based on this information, waste impacts would be

16 SMALL for two new nuclear plants located at the STP site.

17 8.1.14 Summary of Impacts of New Nuclear Generation

18 Table 8–2 summarizes the environmental impacts of the new nuclear alternative compared to 

19 continued operation of STP.

20 Table 8–2. Summary of Environmental Impacts of the New Nuclear Alternative

21 Compared to Continued Operation of STP, Units 1 and 2

Category New Nuclear Generation

(proposed infrastructure)

Continued STP Operation

Air quality SMALL SMALL

Surface water SMALL SMALL

Groundwater SMALL SMALL

Aquatic resources SMALL SMALL

Terrestrial resources SMALL SMALL

Human health SMALL SMALL to MODERATE

Land use SMALL SMALL

Socioeconomics SMALL to LARGE SMALL

Transportation MODERATE to LARGE SMALL

Aesthetics SMALL SMALL

Historic & archaeological SMALL SMALL

Waste management SMALL SMALL

8.2

23 In this section, the NRC staff evaluates the environmental impacts of natural gas-fired 

24 combined-cycle (NGCC) generation at the STP site.

22 Natural Gas-Fired Combined-Cycle Generation
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1 Natural gas accounted for 38 percent of all electricity generated in the ERCOT service area in 

2 2010, accounting for the second greatest share of electrical power (ERCOT 2011a). 

3 Development of new natural gas-fired plants may be affected by perceived or actual action to 

4 limit greenhouse gas emissions, although they produce markedly fewer greenhouse gases per 

5 unit of electrical output than coal-fired plants. Natural gas-fired plants are a feasible,

6 commercially available option for providing electrical generating capacity beyond STPNOC’s 

7 current license expiration. NRC examined NGCC because NGCC can operate with high 

8 thermal efficiency (approximately 60 percent for some units) and is capable of economically 

9 providing baseload power. Therefore, NRC considered NGCC generation a reasonable 

10 alternative to STP license renewal.

11 NGCC plants differ significantly from coal-fired boilers and existing nuclear plants. NGCC 

12 plants derive the majority of their electrical output from a gas-turbine cycle and then generate 

13 additional power—without burning any additional fuel—through a second, steam-turbine cycle. 

14 The first gas turbine stage (similar to a large jet engine) burns natural gas, which turns a 

15 driveshaft that powers an electric generator. The exhaust gas from the gas turbine is still hot 

16 enough to boil water to steam. Ducts carry the hot exhaust to a heat-recovery steam generator, 

17 which produces steam to drive a steam turbine and produce additional electrical power. The 

18 combined-cycle approach is significantly more efficient than any one cycle on its own; thermal 

19 efficiency can exceed 60 percent. Because the NGCC alternative derives much of its power 

20 from a gas turbine cycle, and because it wastes less heat than the existing STP units, it requires 

21 significantly less cooling water than the coal-fired alternative or the existing STP.

22 To replace the 2,500 MWe power that STP generates, NRC considered four hypothetical 

23 gas-fired units, each with a net capacity of 640 MWe. For purposes of this analysis, the 

24 hypothetical units would be similar to General Electric’s (GE’s) H-class gas fired combined-cycle 

25 units. While any number of commercially available combined-cycle units could be installed in a 

26 variety of combinations to replace the power currently produced by STP, GE’s H-class units are 

27 highly efficient models that would be used to minimize environmental impacts. Other 

28 manufacturers, like Siemens, offer similarly high efficiency models.

29 GE’s H-class combined-cycle generating units operate at a heat rate of 5,690 British thermal 

30 units per kilowatt hours (BTU/kWh), or nearly 60 percent thermal efficiency (GE 2011). As 

31 noted above, this NGCC alternative would require much less cooling water than STP because 

32 the NGCC units operate at a higher thermal efficiency and because they require much less 

33 water for steam cycle condenser cooling. Therefore, the NRC staff assumed that the existing 

34 cooling water system, including the intakes and discharges on the MCR and the Colorado River, 

35 would be sufficient for this alternative.

36 Construction of onsite visible structures would include the natural gas turbine buildings and 

37 heat-recovery steam generators (which may be enclosed in a single building), exhaust stacks, 

38 and, if necessary, equipment associated with a natural gas pipeline, such as a compressor 

39 station. The NGCC alternative at the STP site would use the existing STP transmission system. 

40 Based on GEIS estimates, the plant would require approximately 312 ac (126 ha), which 

41 includes a new pipeline that would run approximately 2 mi (3 km) from the STP site to an 

42 existing pipeline.

This 2,560 MWe NGCC plant would consume 110 billion cubic feet (ft3 43 ) (3,111 million cubic 

meters (m3

)) of natural gas annually, assuming an average heat content of 1,029 BTU/ft3 44

45 (EIA 2009). Natural gas would be extracted from the ground through wells, then treated to 

46 remove impurities (like hydrogen sulfide), and blended to meet pipeline gas standards before 

47 being piped through the state pipeline system to the plant site. This NGCC alternative would 
Environmental Impacts of Alternatives

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1 produce relatively little waste, primarily in the form of spent catalysts used for emissions 

2 controls.

3 To build the NGCC plant, site crews would clear vegetation from the site, prepare the site 

4 surface, and begin excavation before other crews begin actual construction on the plant or any 

5 associated infrastructure, including the 2 mi (3 km) pipeline. The NGCC alternative at the STP 

6 site would use the existing STP transmission system. Construction materials would be 

7 delivered via rail spur, truck, or barge. For the proposed construction of Units 3 and 4, 

8 STPNOC proposed dredging near the current barge slip and upgrading the existing rail spur to 

9 accommodate shipments of construction materials (STPNOC 2010b). The NRC staff finds this 

10 to be reasonable and assumed that dredging and rail spur upgrades would be required for the 

11 NGCC alternative.

12 8.2.1 Air Quality

13 As discussed in Section 2.2.2.1, the STP site is located in central Matagorda County, Texas, at 

14 the southern edge of the Metropolitan Houston-Galveston Intrastate Air Quality Control Region 

15 (40 CFR 81.38). The Corpus Christi-Victoria Intrastate Air Quality Control Region 

16 (40 CFR 81.136) lies immediately south and west of Matagorda County. EPA has designated 

17 all of the counties in these Air Quality Control Regions adjacent to the STP site as in compliance 

18 with the National Ambient Air Quality Standards (40 CFR 81.344) except Brazoria County to the 

19 north; Brazoria County is classified Nonattainment/Severe relative to the 8-hour ozone standard 

20 (EPA 2011b).

21 Construction activities would cause some localized temporary air quality effects because of 

22 emissions and fugitive dust from operation of earth-moving and material-handling equipment. 

23 Emissions from workers’ vehicles and motorized construction equipment would be temporary. 

24 NRC assumed that construction crews would use dust-control practices to control and reduce 

25 fugitive dust. STPNOC proposed such activities during construction of proposed Units 3 and 4 

26 (STPNOC 2010b), and §111.145 of TCEQ’s regulations require dust suppression control during 

27 the construction of facilities and parking lots.

28 A new NGCC plant would qualify as a new major-emitting industrial facility and would be subject 

29 to PSD requirements under the Clean Air Act (CAA) (EPA 2011c). The NGCC plant would need 

30 to comply with the standards of performance for electric utility steam generating units set forth in 

31 40 CFR Part 60 Subpart KKKK. The plant would also require an operating permit from TCEQ. 

32 In STPNOC’s ER for Units 3 and 4, STPNOC stated that “[a]ir emissions sources would be 

33 managed in accordance with Federal, Texas, and local air quality control laws and regulations.” 

34 Likewise, NRC assumed that the NGCC plant would also operate in accordance with Federal, 

35 Texas, and local air quality control laws and regulations.

36 Subpart P of 40 CFR Part 51 contains the visibility protection regulatory requirements, including 

37 the review of new sources that would be constructed in the attainment or unclassified areas and 

38 may affect visibility in any Federal Class I area. If an NGCC alternative was located close to a 

39 mandatory Class I area, additional air pollution control requirements would be required. As 

40 noted in Section 2.2.2.1, there are no mandatory Class I Federal areas within 50 mi of the STP 

41 site.

42 The NRC projects the following emissions based on data published by the EIA, EPA, and on 

43 performance characteristics and emissions controls:

44 • sulfur oxides—192 tons (174 MT) per year, 

45 • nitrogen oxides—839 tons (761 MT) per year, 
Environmental Impacts of Alternatives

8-17

1 • carbon dioxide—6,068,000 tons (5,995,000 MT) per year, 

2 • carbon monoxide—847 tons (768 MT) per year, 

3 • total suspended particles (TSP)—373 tons (338 MT) per year, and

4 • particulate matter ≤10 μm or PM10—373 tons (338 MT) per year. 

5 8.2.1.1 Sulfur Oxide and Nitrogen Oxide

6 A new NGCC plant would have to comply with Title IV of the CAA (42 USC 7651) reduction 

7 requirements for sulfur oxides and nitrogen oxides, which are the main precursors of acid rain 

8 and the major cause of reduced visibility. Title IV establishes maximum sulfur oxide and 

9 nitrogen oxide emission rates from existing plants and a system of sulfur oxide emission 

10 allowances that can be used, sold, or saved for future use by new plants. In addition, in 

11 August 2011, EPA published the Cross-State Air Pollution Rule, which included reductions of 

12 sulfur oxides and nitrogen oxides in Texas. According to the rule, NGCC plants would need to 

13 comply with the new reductions by 2012.

14 As stated above, the new NGCC alternative would produce 192 tons (174 MT) per year of sulfur 

15 oxides and 839 tons (761 MT) per year of nitrogen oxides based on the use of the dry low16 nitrogen oxide combustion technology and use of the selective catalytic reduction (SCR) to 

17 significantly reduce nitrogen oxide emissions. The new plant would be subjected to the 

18 continuous monitoring requirements for sulfur oxides and nitrogen oxides, as specified in 

19 40 CFR Part 75. The current State Implementation Plan (SIP) for Texas includes a cap and 

20 trade program for sulfur and nitrogen oxides. To operate the NGCC plant, sulfur dioxide 

21 allowance would need to be purchased from the open market or an existing fossil-fired plant 

22 would need to be shut down and those credits would need to be applied to the new plants 

23 (STPNOC 2010a). Thus, provided the plant operator is able to purchase sufficient allowances 

24 to operate, the NGCC alternative would not add to the net regional sulfur or nitrogen oxide

25 emissions, although it might do so locally.

26 8.2.1.2 Greenhouse Gases

27 The new plant would release greenhouse gases, such as carbon dioxide and methane. The 

28 plant would be subjected to the continuous monitoring requirements for carbon dioxide, as 

29 specified in 40 CFR Part 75. The NGCC plant would emit approximately 6.1 million tons 

30 (approximately 6.0 million MT) per year of carbon dioxide emissions.

31 On July 12, 2012, EPA issued a final rule tailoring the applicability criteria that determine which 

32 stationary sources and modification to existing projects become subject to permitting 

33 requirements for greenhouse emissions under the PSD and Title V Programs of the CAA 

34 (77 FR 41051). According to the Tailoring Rule, greenhouse gases are a regulated new source 

35 review pollutant under the PSD major source permitting program if the source is otherwise 

36 subject to PSD (for another regulated new source review pollutant) and has a greenhouse gas 

37 potential to emit equal to or greater than 75,000 tons (68,000 MT) per year of carbon dioxide 

38 equivalent (“carbon dioxide equivalent” adjusting for different global warming potentials for 

39 different greenhouse gases). Such sources would be subject to best available control 

40 technology (BACT), although EPA has yet to determine BACT for greenhouse gases.

41 EPA issued a Federal Implementation Plan (FIP) on May 3, 2011, to permit greenhouse 

42 gas-emitting sources in states that do not have measures to lower greenhouse gases in their 

43 SIP. Because Texas has not updated its SIP to include greenhouse gases, EPA will be the 

44 official permitting authority for greenhouse gas-emitting sources in Texas if the SIP is not 

45 updated before the NGCC plant begins operations.
Environmental Impacts of Alternatives

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1 8.2.1.3 Particulates

2 The new NGCC alternative would produce 373 tons (338 MT) per year of TSP, all of which 

3 would be emitted as PM10. STPNOC (2010a) indicated that all PM10 emissions would be 

4 particulate matter, ≤2.5 μm or PM2.5. DOE (2007) evaluated the emissions from a hypothetical 

5 560 MWe NGCC unit using BACT to meet the emission requirements of the 2006 New Source 

6 Performance Standards. DOE concluded that emissions from particulates would be negligible 

7 because NGCC uses natural gas as fuel; therefore, NGCC plants would not require emissions 

8 controls equipment or features to reduce these emissions.

9 During the construction of an NGCC plant, onsite activities would also generate fugitive dust. 

10 Vehicles and motorized equipment would create exhaust emissions during the construction 

11 process. These impacts would be intermittent and short-lived; however, to minimize dust 

12 generation, construction crews would use applicable dust-control measures, as described 

13 above.

14 8.2.1.4 Hazardous Air Pollutants

15 In December 2000, EPA issued regulatory findings (65 FR 79825) on emissions of hazardous 

16 air pollutants (HAPs) from electric utility steam-generating units, which said that natural 

17 gas-fired plants emit HAPs such as arsenic, formaldehyde, and nickel and stated the following: 

18 Also in the utility RTC (Report to Congress), the EPA indicated that the impacts 

19 due to HAP emissions from natural gas-fired electric utility steam generating 

20 units were negligible based on the results of the study. The Administrator finds 

21 that regulation of HAP emissions from natural gas-fired electric utility steam 

22 generating units is not appropriate or necessary.

23 As a result of EPA’s conclusion, the NRC staff finds no significant air quality effects from HAPs. 

24 8.2.1.5 Conclusion

25 Based on this information, the overall air quality impacts of a new NGCC plant located at the 

26 STP site would be SMALL to MODERATE. Impacts would not be noticeable for sulfur and 

27 nitrogen oxides because the Texas SIP requires a Cap and Trade Program, and there would be 

28 no net increase in sulfur and nitrogen oxide emissions. Based on analyses from DOE (2007) 

29 and EPA (2000, 65 FR 79825), TSPs and HAPs would have negligible impacts. Greenhouse 

30 gas emissions would be noticeable; carbon dioxide emissions would be two orders of magnitude 

31 larger than the threshold in EPA’s tailoring rule for greenhouse gas (75,000 tons or 68,000 MT) 

32 per year of carbon dioxide equivalent), which would trigger a regulated new source review.

33 8.2.2 Surface Water Resources

34 STPNOC did not propose using any surface water during the construction of Units 3 and 4 

35 (NRC 2011). As a new NGCC plant would occupy a much smaller footprint relative to new 

36 nuclear units, and its construction would entail less extensive excavation and earthwork, NRC 

37 expects that surface water would not be used during construction for the NGCC alternative.

38 Some temporary impacts to surface water quality may result from dredging activities in the 

39 Colorado River near the barge slip and from increased sediment loading in stormwater runoff 

40 from active construction areas. Due to the short-term nature of the dredging activities, the 

41 hydrologic alterations and sedimentation would be localized and temporary. Dredging would 

42 also be conducted under a permit from the USACE requiring the implementation of BMPs to 

43 minimize impacts. Runoff from construction areas would be controlled under a State-issued 

44 TPDES general permit that would require implementation of a stormwater pollution prevention 
Environmental Impacts of Alternatives

8-19

1 plan and associated BMPs to prevent or significantly mitigate soil erosion and contamination of 

2 stormwater runoff from construction activities.

3 For facility operations, the NGCC alternative would require much less cooling water than STP, 

4 Units 1 and 2, and consumptive water use would be much less. It is expected that use of the 

5 existing intake and discharge infrastructure on the MCR and the Colorado River would be 

6 sufficient to support this alternative. Surface water withdrawals would be subject to, and would 

7 remain well within, STPNOC’s existing water rights, and effluent discharges and stormwater 

8 discharges associated with industrial activity would subject to a revised State-issued TPDES 

9 permit under this alternative. 

10 In consideration of the above, the impacts on surface water use and quality from construction 

11 and operations under the NGCC alternative would be SMALL.

12 8.2.3 Groundwater Resources

13 Construction-related ground disturbance and excavation work would be substantially less than 

14 that described for the new nuclear alternative. Although groundwater dewatering of foundation 

15 excavations for a new NGCC plant would likely be required, slurry walls and wells were 

16 proposed for use to minimize potential adverse effects from dewatering both on site and off site 

17 (NRC 2011). Application of BMPs in accordance with a state-issued NPDES general permit, 

18 including appropriate waste management and spill prevention practices, would prevent or 

19 minimize any groundwater quality impacts during construction.

20 STPNOC assumed that a fossil-fuel-fired generation facility would be located adjacent to the 

21 STP, Units 1 and 2, site to use the existing infrastructure, including continued use of existing 

22 onsite groundwater production wells at STP. Groundwater use for construction of a new NGCC 

23 plant would be substantially less than the volume required for new nuclear units under this 

24 alternative by virtue of the smaller footprint involved for excavation, earthwork, and structural 

25 work. This would encompass such uses as potable and sanitary uses, concrete production, 

26 dust suppression and soil compaction, and other uses.

27 For NGCC plant operations, NRC assumed that the NGCC alternative would entail the same 

28 relative ratio of groundwater use to surface water use as that used at STP, Units 1 and 2. This 

29 includes the use of groundwater for freshwater and service water makeup, potable and sanitary 

30 uses, and fire protection. Consequently, it is expected that total groundwater usage and 

31 associated aquifer effects would likely be much less under this alternative than those under 

32 current STP operations. This is because of the fewer number of auxiliary systems requiring 

33 groundwater and the much smaller workforce under the NGCC alternative.

34 Based on this information, the overall impact on groundwater use and quality from construction 

35 and operations under the NGCC alternative would be SMALL.

36 8.2.4 Aquatic Ecology

37 Construction activities for the NGCC alternative (such as construction of heavy haul roads and 

38 the power blocks) could affect drainage areas or other onsite aquatic features. NRC assumed 

39 that the plant operator would install temporary and permanent erosion and sediment control 

40 measures to minimize the flow of disturbed soils into ditches and wetlands. Such BMPs would 

41 likely be described in a TPDES general permit relating to stormwater discharges for construction 

42 activities. To bring new materials to the site, NRC assumed the plant operator would dredge 

43 near the barge slip to transport some materials using barges. Permits and certifications from 

44 the USACE and other agencies would require the implementation of BMPs to minimize impacts. 
Environmental Impacts of Alternatives

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1 Due to the short-term nature of the dredging activities, the hydrological alterations to aquatic 

2 habitats would be localized and temporary.

3 During operations, the NGCC alternative would require less cooling water to be withdrawn from 

4 the Colorado River than STP, Units 1 and 2, requires. Therefore, the number of fish and other 

5 aquatic organisms affected by impingement and entrainment would be less for an NGCC 

6 alternative than for those associated with license renewal. The NGCC alternative would also 

7 discharge less thermal effluent because less cooling water would be required. STPNOC’s 

8 TPDES permit limits the daily discharge to 144 million gpd and shall not exceed 12.5 percent of 

9 the flow of the Colorado River at the discharge point (TCEQ 2005). STPNOC has discharged to 

10 the Colorado River once during the operation of STP in 1997 as part of a system test 

11 (STPNOC 2010a). Because the thermal discharge would be smaller than STP, Units 1 and 2, 

12 the number of fish and other aquatic organisms affected by heat shock would be less for an 

13 NGCC alternative than for those associated with license renewal. 

14 The NGCC plant emission has specific impacts to the aquatic ecology. The cooling system for 

15 a new NGCC plant would have similar chemical discharges as STP, but the air emissions from 

16 the NGCC plant would emit particulates that would settle onto the river surface and introduce a 

17 new source of pollutants that would not exist if STP continued operating. However, the flow of 

18 the Colorado River would dissipate pollutants, which would decrease the concentration of 

19 pollutants and minimize the exposure of fish and other aquatic organisms to pollutants.

20 Construction activities would require BMPs; dredging would be short-term; the surface water 

21 withdrawal and discharge for this alternative would be less than for STP, Units 1 and 2; and 

22 pollutants would dissipate within the Colorado River (minimizing exposure concentrations to 

23 aquatic resources). Therefore, impacts on aquatic ecology would be SMALL.

24 8.2.5 Terrestrial Ecology

25 Constructing the NGCC alternative would require approximately 312 ac (126 ha), which includes 

26 a new pipeline that would run approximately 2 mi (3 km) from the STP site to an existing 

27 pipeline. These land disturbances form the basis for impacts on terrestrial ecology.

28 If the NGCC alternative was constructed at the STP site, construction would likely affect a 

29 variety of habitats and land uses, including industrial land (buildings, parking areas, and 

30 mowed-maintained fields), drainage ditches, scattered small palustrine wetlands, scrub-shrub 

31 habitat, and mixed grassland habitat where abandoned farm lands previously existed prior to 

32 construction of Units 1 and 2. Most of these areas have been mildly to extensively disturbed 

33 during the construction and operation of Units 1 and 2 and other human activities. After the 

34 completion of the new units, the plant operator would likely grade, landscape, and replant the 

35 areas used for temporary building support, which is similar to what STPNOC proposed to do 

36 after completion of proposed new nuclear Units 3 and 4 (STPNOC 2010b). The majority of 

37 permanently affected areas would be maintained (e.g., mowed) and industrial areas. The plant 

38 operator would likely implement BMPs to minimize impacts to wetlands, and the plant operator 

39 would be required to comply with the USACE 404 permits. Construction activities could also 

40 adversely affect onsite wildlife through noise, increased light pollution, and increased traffic. 

41 However, these impacts would be temporary and minor.

42 Gas extraction and collection would also affect terrestrial ecology in offsite gas fields, although 

43 much of this land is likely already disturbed by gas extraction, and the incremental effects of this 

44 alternative on gas field terrestrial ecology are difficult to gauge.

45 Construction of the 2-mi (3-km) natural gas pipeline could also increase habitat fragmentation. 

46 To the extent possible, STPNOC would route the pipeline through previously disturbed areas 
Environmental Impacts of Alternatives

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1 (STPNOC 2010a). Threatened and endangered species may also be affected by construction 

2 of the natural gas pipeline. Long-linear projects, such as pipelines, can often be sited to avoid 

3 sensitive areas. Once construction is completed, impacts would be minimal, especially in 

4 previously disturbed areas.

5 Because many construction-related impacts would be temporary, and because the majority of 

6 long-term construction impacts would occur within previously disturbed areas, impacts on 

7 terrestrial resources would be SMALL.

8 8.2.6 Human Health

9 An NGCC plant would emit criteria air pollutants, but generally in smaller quantities than a 

10 coal-fired plant (except nitrogen oxide, which requires additional controls to reduce emissions). 

11 The human health effects of NGCC generation are generally low, although in Table 8–2 of the 

12 GEIS (NRC 1996), the NRC identified cancer and emphysema as potential health risks from 

13 natural gas-fired plants. Nitrogen oxide emissions contribute to ozone formation, which in turn 

14 contributes to human health risks. Emission controls on this NGCC alternative maintain 

15 nitrogen oxide emissions well below air quality standards established for the purposes of 

16 protecting human health, and emissions trading or offset requirements mean that overall 

17 nitrogen oxide in the region would not increase. Health risks to workers may also result from 

18 handling spent catalysts that may contain heavy metals.

19 Overall, human health risks to occupational workers and to members of the public from NGCC 

20 plant emissions sited at the STP site would likely be SMALL.

21 Noise during plant operations would be limited to industrial processes and communications. 

22 Pipelines delivering natural gas fuel could be audible off site near compressor stations. Pipeline 

23 companies would need to adhere to local ordinances regarding maximum noise levels during 

24 construction and at compressor stations. Therefore, impacts from noise would likely be SMALL.

25 8.2.7 Land Use 

26 The GEIS generically evaluates the impact of constructing and operating various replacement 

27 power plant alternatives on land use, both on and off each plant site. The analysis of land use 

28 impacts focuses on the amount of land area that would be affected by the construction and 

29 operation of a four-unit NGCC plant at the STP site.

30 Based on scaled GEIS estimates and information provided by STPNOC in its ER, approximately 

31 312 ac (126 ha) of land would be needed to support an NGCC alternative to replace STP. This 

32 amount of land use would include other plant structures and associated infrastructure, such as 

33 the new 2-mi (3-km) pipeline, and is unlikely to exceed 312 ac (126 ha), excluding land for 

34 natural gas wells and collection stations.

35 In addition to onsite land requirements, land would be required off site for natural gas wells and 

36 collection stations. Scaling from GEIS estimates, approximately 9,600 ac (3,885 ha) would be 

37 required for wells and collection stations to bring the gas to the plant. Gas well and collection 

38 stations could noticeably alter land use in those areas, although most of this land requirement 

39 would occur in areas where gas extraction already occurs.

40 The elimination of uranium fuel for STP could partially offset offsite land requirements. Scaling 

41 from GEIS estimates approximately 2,560 ac (1,036 ha) would not be needed for mining and 

42 processing uranium during the operating life of the plant. Overall land-use impacts from the 

43 natural gas alternative (considering the amount of additional offsite land needed for NGCC gas 
Environmental Impacts of Alternatives

8-22

1 pipeline infrastructure and gas well and collection station development) could range from

2 SMALL to MODERATE.

3 8.2.8 Socioeconomics

4 Socioeconomic impacts are defined in terms of changes to the demographic and economic 

5 characteristics and social conditions of a region. For example, the number of jobs created by 

6 the construction and operation of a power plant could affect regional employment, income, and 

7 expenditures. Two types of jobs would be created by this alternative: (1) construction-related 

8 jobs, which are transient, short in duration, and less likely to have a long-term socioeconomic 

9 impact; and (2) power plant operation jobs, which have the greater potential for permanent, 

10 long-term socioeconomic impacts. Workforce requirements for the construction and operation 

11 of the NGCC alternative were evaluated to measure their possible effects on current 

12 socioeconomic conditions.

13 Scaling from GEIS estimates, the construction workforce would peak at 3,200 workers. 

14 STPNOC projected a maximum construction workforce of 2,028 workers (STPNOC 2010a). 

15 STPNOC’s estimate appears reasonable; therefore, it is used in this analysis. The relative 

16 economic impact of this many workers on the local economy and tax base would vary, with the 

17 greatest impacts occurring in the communities where the majority of construction workers would 

18 reside and spend their income. As a result, local communities could experience a short-term 

19 economic “boom” from increased tax revenue and income generated by construction 

20 expenditures and the increased demand for temporary (rental) housing and business services. 

21 Some construction workers could relocate to Matagorda and surrounding counties in order to be 

22 closer to the construction work site. However, given the proximity of STP to the Houston 

23 metropolitan area, many construction workers could commute to the STP site, thereby lessening 

24 the need for additional rental housing near STP. 

25 After completing the installation of the four-unit NGCC plant, local communities could 

26 experience a return to pre-construction economic conditions. Based on this information, and 

27 given the number of workers, socioeconomic impacts during construction in communities near 

28 the STP site could range from SMALL to MODERATE.

29 Scaling from GEIS estimates, the plant operation workforce would be 400 workers. STPNOC 

30 estimated a plant operations workforce of approximately 97 workers. The STPNOC estimate 

31 appears to be reasonable and is consistent with trends toward lowering labor costs by reducing 

32 the size of plant operations workforces. The amount of property taxes paid under the NGCC 

33 alternative may increase if additional land is required off site to support this alternative. 

34 Socioeconomic impacts during operations could range from SMALL to MODERATE as the STP 

35 site transitions to the new NGCC power plant. The potential reduction in overall employment at 

36 STP could affect property tax revenue and income in local communities and businesses. In 

37 addition, the permanent housing market could also experience increased vacancies and 

38 decreased prices if operations workers and their families move out of the region.

39 8.2.9 Transportation

40 Transportation impacts associated with construction and operation of a four-unit, NGCC plant 

41 would consist of commuting workers and truck deliveries of construction materials to the STP 

42 site. During periods of peak construction activity, up to 2,028 workers could be commuting daily 

43 to the site (STPNOC 2010a). Workers commuting to the STP site would primarily use two-lane 

44 roads. The volume of traffic on these roads, and especially FM 521, would increase 

45 substantially. In addition to commuting workers, trucks would be transporting construction 

46 materials and equipment to the worksite, thus increasing the amount of traffic on local roads. 
Environmental Impacts of Alternatives

8-23

1 The increase in vehicular traffic would peak during shift changes, resulting in temporary levels of 

2 service impacts and delays at intersections. Pipeline construction and modification to existing 

3 natural gas pipeline systems could also have a temporary impact. Some power plant 

4 components and materials could also be delivered by train or barge. Train deliveries could 

5 cause additional traffic delays at railroad crossings. Based on this information, traffic-related 

6 transportation impacts during construction could range from SMALL to MODERATE.

7 Traffic-related transportation impacts would be greatly reduced after completing the installation 

8 of the new NGCC units. Transportation impacts would include daily commuting by the operating 

9 workforce, equipment and materials deliveries, and the removal of commercial waste material to 

10 offsite disposal or recycling facilities by truck. During operations, the estimated number of 

11 operations workers commuting to and from STP would be 97 workers (STPNOC 2010a). Since 

12 fuel is transported by pipeline, the transportation infrastructure would experience little to no 

13 increased traffic from plant operations. Traffic-related transportation impacts would be 

14 considerably less than current operations because the new NGCC power plant would employ 

15 far fewer workers than STP, Units 1 and 2. Overall, transportation impacts would be SMALL 

16 during plant operations.

17 8.2.10 Aesthetics

18 The analysis of aesthetic impacts focuses on the degree of contrast between the NGCC 

19 alternative and the surrounding landscape and the visibility of the NGCC plant. During 

20 construction, all of the clearing and excavation would occur on the STP site. These activities 

21 may be visible from offsite roads, particularly FM 521. Since the STP site already appears 

22 industrial, construction of the NGCC power plant would appear similar to onsite activities during 

23 refueling outages.

24 The four NGCC units could be approximately 100 ft (30 m) tall, with two exhaust stacks up to 

25 175 ft (53 m) tall. The facility would be visible off site during daylight hours, and some 

26 structures may require aircraft warning lights. The power plant would be smaller and less 

27 noticeable than STP, Units 1 and 2, which has a reactor building height of approximately 250 ft 

28 (76 m) (STPNOC 2010b). Noise generated during NGCC power plant operations would be 

29 limited to routine industrial processes and communications. Pipelines delivering natural gas fuel 

30 could be audible off site near gas compressor stations.

31 In general, given the industrial appearance of the STP site, the new NGCC power plant would 

32 blend in with the surroundings if the existing STP, Units 1 and 2, remains. Aesthetic changes 

33 would be limited to the immediate vicinity of the existing STP site, and any impacts would be 

34 SMALL.

35 8.2.11 Historic and Archaeological Resources

36 The same considerations, discussed in Section 8.1.11, for the impact of the construction of a 

37 new nuclear plant on historic and archaeological resources apply to the construction activities 

38 that would occur on the STP site for an NGCC plant. As described in Section 2.2.10, much of 

39 the STP site has been previously disturbed by the construction of STP, Units 1 and 2. In 

40 addition, in preparation for the COL application for Units 3 and 4, STPNOC conducted a cultural 

41 resources assessment of the STP site. STPNOC reviewed existing information for the STP site 

42 and the area within a 10-mi (16-km) radius. STPNOC concluded that any cultural resource sites 

43 that may have existed on site would no longer retain their integrity because the area was heavily 

44 disturbed during the construction of Units 1 and 2 (STPNOC 2010b). In December 2006, 

45 STPNOC reported these findings to the SHPO at the Texas Historical Commission. The SHPO 
Environmental Impacts of Alternatives

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1 concurred, in January 2007, that there would be no impacts to historic properties

2 (STPNOC 2006; THC 2007).

3 There is a low potential for cultural resources to be located in previously undisturbed portions of 

4 the STP site. However, if the NGCC units were to be sited within undisturbed areas or within 

5 areas of known cultural sensitivity (historic grave site located on the property and described in 

6 Section 2.2.10), these areas would need to be surveyed by a professional archaeologist to 

7 identify and develop possible mitigation measures to address any adverse effects from project 

8 activities. NRC assumes the plant operator would follow similar procedures to those described 

9 in the final EIS for STP, Units 3 and 4 (NRC 2011), if the plant operator discovered any historic 

10 or cultural resources during ground-disturbing activities associated with building the new units.

11 Studies would be needed for all areas of potential disturbance at the proposed plant site and 

12 along associated corridors where new construction would occur (e.g., the new 2-mi pipeline, 

13 roads, transmission corridors, rail lines, or other rights-of-way (ROWs)). In most cases, 

14 long-linear projects can be sited to avoid areas of greatest sensitivity.

15 The NRC staff determined that the impact of the NGCC alternative at the STP site on historic 

16 and archaeological resources would be SMALL for the following reasons:

17 • NRC (2011) and STPNOC (2010a, 2010b) did not identify any cultural 

18 resources that could be affected by Units 3 and 4. 

19 • The SHPO determined that construction for Units 3 and 4 would not affect 

20 cultural and historic resources. 

21 • Long-linear projects (e.g., pipelines) can usually be sited to avoid sensitive 

22 areas. 

23 • NRC assumes that the plant operator would follow environmental compliance 

24 procedures for new ground-disturbing activities.

25 8.2.12 Environmental Justice

26 The environmental justice impact analysis evaluates the potential for disproportionately high and 

27 adverse human health, environmental, and socioeconomic effects on minority and low-income 

28 populations that could result from the construction and operation of a new power plant. As 

29 previously discussed in Section 8.1.12, such effects may include human health, biological, 

30 cultural, economic, or social impacts. Some of these potential effects have been identified in 

31 resource areas discussed in this SEIS. For example, increased demand for rental housing 

32 during plant construction could disproportionately affect low-income populations. Minority and 

33 low-income populations are subsets of the general public living near the STP site, and all are 

34 exposed to the same hazards generated from constructing and operating a new NGCC plant. 

35 Section 4.9.7, “Environmental Justice,” presents demographic information about minority and 

36 low-income populations residing in the vicinity of the STP site. 

37 Potential impacts to minority and low-income populations from the construction and operation of 

38 a new NGCC plant at the STP site would mostly consist of environmental and socioeconomic 

39 effects (e.g., noise, dust, traffic, employment, and housing impacts). Noise and dust impacts 

40 during construction would be short-term and primarily limited to onsite activities. Minority and 

41 low-income populations residing along site access roads would be directly affected by increased 

42 commuter vehicle and truck traffic. However, because of the temporary nature of construction, 

43 these effects would only occur during certain hours of the day and are unlikely to be high and 

44 adverse. Increased demand for rental housing during construction could also affect low-income 

45 populations living near STP. However, given the proximity of STP to the Houston metropolitan 
Environmental Impacts of Alternatives

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1 area, many construction workers could commute to the STP site, thereby lessening the 

2 additional need for rental housing.

3 Based on this information, and the analysis of human health and environmental impacts 

4 presented in this SEIS, the construction and operation of a new NGCC power plant would not

5 have disproportionately high and adverse human health and environmental effects on minority 

6 and low-income populations residing in the vicinity of the STP site. 

7 8.2.13 Waste Management

8 During the construction stage of the NGCC generation alternative, land clearing and other 

9 construction activities would generate waste that could be recycled, disposed of on site, or 

10 shipped to an offsite waste disposal facility. Because the alternative would be constructed on or 

11 near the previously disturbed STP site, the amounts of waste produced during land clearing 

12 would be reduced.

13 During the operational stage, spent SCR catalysts, which are used to control nitrogen oxide 

14 emissions from the NGCC plants, would make up the majority of the waste generated by this 

15 alternative.

16 According to the GEIS (NRC 1996), an NGCC plant would generate minimal waste. Waste 

17 impacts would therefore be SMALL for an NGCC alternative located at the STP site.

18 8.2.14 Summary of Impacts for the NGCC Generation Alternative

19 Table 8–3 summarizes the environmental impacts of the NGCC alternative compared to 

20 continued operation of STP.

21 Table 8–3. Summary of Environmental Impacts of the NGCC Alternative

22 Compared to Continued Operation of STP

Category

Natural Gas Combined-Cycle 

Generation Continued STP Operation

Air quality SMALL to MODERATE SMALL

Surface water SMALL SMALL

Groundwater SMALL SMALL

Aquatic resources SMALL SMALL

Terrestrial resources SMALL SMALL

Human health SMALL SMALL to MODERATE

Land use SMALL to MODERATE SMALL

Socioeconomics SMALL to MODERATE SMALL

Transportation SMALL to MODERATE SMALL

Aesthetics SMALL SMALL

Historic & archaeological SMALL SMALL

Waste management SMALL SMALL
Environmental Impacts of Alternatives

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8.3

2 In this section, the NRC staff evaluates the environmental impacts of supercritical coal-fired 

3 generation at the STP site.

1 Supercritical Coal-Fired Generation

4 Coal-fired generation accounted for 40 percent of all electricity generated in the ERCOT service 

5 area in 2010, accounting for the greatest share of electrical power (ERCOT 2011a). 

6 Furthermore, the EIA projects that coal-fired power plants will account for the greatest share of 

7 capacity additions through 2035—more than natural gas, nuclear, or renewable generation 

8 options (EIA 2011a). Development of new coal-fired plants may be affected by perceived or 

9 actual action to limit greenhouse gas emissions. TCEQ has recently granted permits to several 

10 recently proposed coal-fired plants (TCEQ 2011). Supercritical coal-fired plants are feasible, 

11 commercially available options for providing electrical generating capacity beyond STPNOC’s 

12 current license expiration. Therefore, NRC considered supercritical coal fired-generation a 

13 reasonable alternative to STP license renewal.

14 Supercritical technologies are increasingly common in new coal-fired plants. Supercritical 

15 facilities operate at higher temperatures and pressures than most existing coal-fired plants. At 

16 the critical point, there is no change of state when pressure is increased or if heat is added. For 

17 states above the critical point, the steam is supercritical. Operating at higher temperatures and 

18 pressures allows the supercritical coal-fired alternative to operate at a higher thermal efficiency 

19 than subcritical coal-fired power plants. While supercritical facilities are more expensive to 

20 construct, they consume less fuel for a given output, reducing environmental impacts. Based on 

21 technology forecasts from EIA, the NRC staff expects that a new, supercritical coal-fired plant 

22 would operate at a heat rate of 8,740 Btu/kWh (EIA 2011b).

23 In a supercritical coal-fired power plant, burning coal heats pressurized water. As the 

24 supercritical steam and water mixture moves through plant pipes to a turbine generator, the 

25 pressure drops. The mixture flashes to steam. The heated steam expands across the turbine 

26 stages, which then spin and turn the generator to produce electricity. After passing through the 

27 turbine, any remaining steam is condensed back to water in the plant’s condenser.

28 To replace the 2,500 MWe of power that STP generates, the NRC staff considered four 

29 hypothetical coal-fired units, each with a net capacity of 640 MWe. The hypothetical coal-fired 

30 plant would require a similar amount of water as STP, Units 1 and 2. Therefore, the NRC staff 

31 assumed that the existing cooling water system, including the intakes and discharges on the 

32 MCR and the Colorado River, would be sufficient for this alternative. The coal-fired alternative 

33 at the STP site would also use the existing STP transmission system.

34 The hypothetical 2,560 MWe power plant would consume 11.4 million tons (10.4 MT) of coal 

35 annually, based an average heat content of 8,200 British thermal units per pound (Btu/lb)

36 (STPNOC 2010a). EPA (2011a) reported that the majority of coal plants within the ERCOT 

37 region use subbituminous coal. The other coal plants used lignite or combined subbituminous 

38 coal with lignite. While lignite is the most common type of coal found in Texas, NRC assumed 

39 that the hypothetical coal plant for this alternative would use subbituminous coal because when 

40 combusted, it releases lower levels of Federal CAA criteria pollutants, such as carbon dioxide, 

41 nitrous oxides, sulfuric oxides, and particulate matter (TCPA 2008).

42 Texas coal plants commonly use Power River Basin coal (STPNOC 2010a; TCPA 2008). Given 

43 current coal mining operations in Wyoming, the coal used in this alternative would likely be 

44 mined in surface mines, then mechanically processed and washed, before being transported—

45 likely by rail—to the power plant site. Limestone for scrubbers would also likely arrive by rail 

46 (STPNOC 2010a). This coal-fired alternative would produce roughly 446,000 tons 

47 (405,000 MT) of ash, and 43 percent (193,000 tons (175,000 MT)) of the ash would be recycled 
Environmental Impacts of Alternatives

8-27

1 for beneficial use (STPNOC 2010a). STPNOC (2010a) estimated that approximately 

2 88,000 tons (80,000 MT) of scrubber sludge would be disposed of on site each year, which was 

3 based on an assumed annual lime usage of approximately 107,000 tons (97 MT). 

4 Approximately 200 ac (81 ha) would be required to dispose of the ash and scrubber waste on

5 site over a 40-year plant life (STPNOC 2010a).

6 Construction of onsite visible structures would include the boilers and heat-recovery steam 

7 generators (which may be enclosed in a single building), exhaust stacks, and an electrical 

8 switchyard. Based on GEIS estimates, the plant would require approximately 4,629 ac 

9 (1,873 ha) of land. STPNOC (2010a) estimates that 353 ac (143 ha) of land would be required. 

10 This estimate appears reasonable; therefore, it is used for this analysis.

11 To build the coal-fired alternative, site crews would clear the plant site of vegetation, prepare the 

12 site surface, and begin excavation before other crews begin actual construction on the plant and 

13 any associated infrastructure. Construction materials would be delivered via rail spur, truck, or 

14 barge. For the proposed construction of Units 3 and 4, STPNOC proposed dredging near the 

15 current barge slip and upgrading the existing rail spur to accommodate shipments of 

16 construction materials (STPNOC 2010b). The NRC staff finds this to be reasonable and 

17 assumed that dredging and rail spur upgrades would be required for the coal-fired alternative.

18 The NRC also considered an integrated gasification combined cycle (IGCC) coal-fired plant. 

19 IGCC is an emerging technology for generating electricity with coal that combines modern coal 

20 gasification technology with both gas turbine and steam turbine power generation. The 

21 technology is cleaner than conventional pulverized coal plants because major pollutants can be 

22 removed from the gas stream before combustion. The IGCC alternative also generates less 

23 solid waste than the pulverized coal-fired alternative. The largest solid waste stream produced 

24 by IGCC installations is slag, a black, glassy, sand-like material that is potentially a marketable 

25 byproduct. The other large-volume byproduct produced by IGCC plants is sulfur, which is 

26 extracted during the gasification process and can be marketed rather than placed in a landfill. 

27 IGCC units do not produce ash or scrubber wastes. In spite of the preceding advantages, the 

28 NRC concluded in the final EIS for the proposed Units 3 and 4 (NRC 2011) that a new IGCC 

29 plant is not a reasonable alternative for the following reasons: 

30 • IGCC plants are more expensive than comparable pulverized coal plants 

31 (NETL 2007). 

32 • The few existing IGCC plants in the U.S. have considerably smaller capacity

33 (approximately 250 MWe each) than STP, Units 1 and 2. 

34 • System reliability of existing IGCC plants has been lower than pulverized coal 

35 plants. 

36 • The existing IGCC plants have had an extended (though ultimately 

37 successful) operational testing period (NPCC 2005). 

38 • A lack of overall plant performance warranties for IGCC plants has hindered 

39 commercial financing (NPCC 2005). 

40 At present, the NRC continues to finds this determination reasonable. While the capacity of 

41 some of the proposed IGCC plants has grown slightly, most proposed IGCC plants are still 

42 considerable smaller than STP, Units 1 and 2. For example, on September 27, 2011, DOE 

43 approved a loan to Summit Texas Clean Energy, LLC, for a 400 MWe IGCC plant to be built 

44 west of Midland-Odessa, Texas (DOE 2011a). Although NRC considered an IGCC plant as an 

45 alternative for the Shearon Harris license renewal SEIS, whose license would also have expired 

46 in 2027, the Shearon Harris nuclear plant is much smaller than STP, Units 1 and 2 (955 MWe
Environmental Impacts of Alternatives

8-28

1 as compared to 2,500 MWe) (NRC 2008). Because of the small capacity of proposed IGCC 

2 plants, the NRC did not find IGCC to be a reasonable alternative for STP, Units 1 and 2. For 

3 these reasons, IGCC plants are not considered further in this SEIS.

4 8.3.1 Air Quality

5 Air quality impacts from coal-fired generation can be substantial because it emits a significant 

6 quantity of sulfur oxides, nitrogen oxides, particulates, carbon monoxide, and HAPs such as 

7 mercury; however, many of these pollutants can be effectively controlled by various 

8 technologies.

9 As discussed in Section 2.2.2.1, STP is located in central Matagorda County, Texas, at the 

10 southern edge of the Metropolitan Houston–Galveston Intrastate Air Quality Control Region 

11 (40 CFR 81.38). The Corpus Christi–Victoria Intrastate Air Quality Control Region 

12 (40 CFR 81.136) lies immediately south and west of Matagorda County. EPA has designated 

13 all of the counties in these Air Quality Control Regions adjacent to the STP site as in compliance 

14 with the National Ambient Air Quality Standards (40 CFR 81.344) except Brazoria County to the 

15 north; Brazoria County is classified Nonattainment/Severe relative to the 8-hour ozone standard 

16 (EPA 2011b).

17 Construction activities would cause some localized temporary air-quality effects because of 

18 emissions and fugitive dust from operation of the earth-moving and material-handling 

19 equipment. Emissions from workers’ vehicles and motorized construction equipment exhaust 

20 would be temporary. NRC assumed that construction crews would use dust-control practices to 

21 control and reduce fugitive dust. STPNOC proposed such activities during construction of 

22 proposed Units 3 and 4 (STPNOC 2010b), and §111.145 of TCEQ’s regulations require dust 

23 suppression control during the construction of facilities and parking lots.

24 A new coal-fired plant would qualify as a new major-emitting industrial facility and would be 

25 subject to PSD requirements of the CAA (EPA 2011c). The coal-fired plant would need to 

26 comply with the standards of performance for electric utility steam generating units set forth in 

27 40 CFR Part 60 Subpart Da and GG. The plant would also require an operating permit from 

28 TCEQ. In STPNOC’s ER for Units 3 and 4, STPNOC stated that “[a]ir emissions sources would 

29 be managed in accordance with Federal, Texas, and local air quality control laws and 

30 regulations.” Likewise, NRC assumed that the coal-fired plant would be operated in accordance 

31 with Federal, Texas, and local air quality control laws and regulations.

32 Subpart P of 40 CFR Part 51 contains the visibility protection regulatory requirements, including 

33 the review of new sources that would be constructed in the attainment or unclassified areas and 

34 may affect visibility in any Federal Class I area. If a coal-fired alternative was located close to a 

35 mandatory Class I area, additional air pollution control requirements would be required. As 

36 noted in Section 2.2.2.1, there are no mandatory Class I Federal areas within 50 mi (80 km) of 

37 the STP site.

38 The emissions from the coal-fired alternative at the STP site, projected by the NRC staff based 

39 on published EIA data, EPA emission factors, and based on performance characteristics for this 

40 alternative and likely emission controls, would be:

41 • sulfur oxides—3,260 tons (2,958 MT) per year, 

42 • nitrogen oxides—2,869 tons (2,595 MT) per year, 

43 • carbon monoxide—784 tons (711 MT) per year, 
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1 • particulate matter PM10—446 tons (405 MT) per year, and

2 • particulate matter PM2.5—223 tons (202 MT) per year. 

3 8.3.1.1 Sulfur Oxides

4 The coal-fired alternative at the STP site would likely use wet, limestone-based scrubbers to 

5 remove sulfur oxides. EPA indicates that this technology can remove more than 95 percent of 

6 sulfur oxides from flue gases. The staff projects total sulfur oxide emissions would be 

7 3,260 tons (2,958 MT) per year. Sulfur oxide emissions from a new coal-fired power plant 

8 would be subject to the requirements of the CAA (42 U.S.C. § 7651 et seq.). These regulations 

9 were enacted to reduce emissions of sulfur dioxide and nitrogen oxide, the two principal 

10 precursors of acid rain, by restricting emissions of these pollutants from power plants. The 

11 current SIP for Texas includes a Cap and Trade Program for sulfur dioxide. To operate the 

12 coal-fired plant, the plant operator would have to purchase sulfur dioxide allowances from the 

13 open market or shut down existing fossil-fired plant(s) and apply the credits to the new plant 

14 (STPNOC 2010a). Thus, provided the plant operator is able to purchase sufficient allowances 

15 to operate, the coal-fired alternative would not add to net regional sulfur dioxide emissions, 

16 although it might do so locally.

17 In addition, in August 2011, EPA published the Cross-State Air Pollution Rule, which included 

18 reductions of sulfur dioxide in Texas. According to the rule, coal-fired plants would need to 

19 comply with the new reductions by 2012.

20 8.3.1.2 Nitrogen Oxides 

21 A coal-fired alternative at the STP site would most likely employ various available nitrogen 

22 oxide-control technologies, which can be grouped into two main categories—combustion 

23 modifications and post-combustion processes. Combustion modifications include low-nitrogen 

24 oxide burners, overfire air, reburning, flue gas recirculation, and operational modifications. 

25 Post-combustion processes include SCR, selective noncatalytic reduction, and hybrid 

26 processes. Effective combination of the combustion modifications and post-combustion 

27 processes reduces nitrogen oxide emissions by up to 95 percent (EPA 1998). STPNOC 

28 indicated in its ER that it would use low-nitrogen oxide burners, overfire air, selective catalytic 

29 reduction, and scrubbers to reduce nitrogen oxide emissions from this alternative 

30 (STPNOC 2010a). Assuming the use of such technologies at the STP site, nitrogen oxide 

31 emissions after scrubbing would be approximately 2,869 tons (2,595 MT) annually.

32 Section 407 of the CAA establishes technology-based emission limitations for nitrogen oxide 

33 emissions. A new coal-fired power plant would be subject to the new source performance 

34 standards for such plants as indicated in 40 CFR 60.44 Subpart Da(a)(1). This regulation limits 

35 the discharge of any gases that contain nitrogen oxides to 200 nanograms (ng) of nitrogen 

36 oxides per joule (J) of gross energy output (equivalent to 1.6 pounds per megawatt-hours 

37 (lb/MWh), based on a 30-day rolling average.

38 The current SIP for Texas includes a Cap and Trade Program for nitrogen oxides. To operate 

39 the coal-fired plant, the plant operator would have to purchase nitrogen oxide allowances from 

40 the open market or shut down existing fossil-fired plant(s) and apply the credits to the new plant 

41 (STPNOC 2010a). Thus, provided the plant operator is able to purchase sufficient allowances 

42 to operate, the coal-fired alternative would not add to net regional nitrogen oxide emissions, 

43 although it might do so locally.

44 8.3.1.3 Greenhouse Gases

45 A coal-fired plant would also have carbon dioxide emissions during operations, as well as during 

46 coal mining, processing, and transportation. The coal-fired plant would emit between 
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1 19.3 million tons (17.5 million MT) and 19.9 million tons (18.1 million MT) of carbon dioxide per 

2 year from coal combustion, depending on the type and quality of the coal burned.

3 On July 12, 2012, EPA issued a final rule tailoring the applicability criteria that determine which

4 stationary sources and modification to existing projects become subject to permitting 

5 requirements for greenhouse emissions under the PSD and Title V Programs of the CAA

6 (77 FR 41051). According to the Tailoring Rule, greenhouse gases are a regulated new source 

7 review pollutant under the PSD major source permitting program if the source is otherwise 

8 subject to PSD (for another regulated new source review pollutant) and has a greenhouse gas 

9 potential to emit equal to or greater than 75,000 tons (68,000 MT) per year of carbon dioxide 

10 equivalent (“carbon dioxide equivalent” adjusting for different global warming potentials for 

11 different greenhouse gases). Such sources would be subject to BACT, although EPA has yet to 

12 determine BACT for greenhouse gases.

13 EPA issued a Federal Implementation Plan (FIP) on May 3, 2011, to permit greenhouse 

14 gas-emitting sources in states that do not have measures to lower greenhouse gases in their 

15 SIP. Because Texas has not updated its SIP to include greenhouse gases, EPA will be the 

16 official permitting authority for greenhouse gas-emitting sources in Texas if the SIP is not 

17 updated before the coal-fired plant begins operations.

18 8.3.1.4 Particulates

19 The new coal-fired power plant would use fabric filters to remove particulates from flue gases 

20 (STPNOC 2010a). The fabric filters would remove 99.9 percent of PM (STPNOC 2010a). EPA 

21 notes that filters are capable of removing in excess of 99 percent of PM and that sulfur dioxide 

22 scrubbers further reduce PM emissions (EPA 2008); therefore, the NRC staff believes the 

23 STPNOC removal factor is appropriate. Based on this information, the new supercritical 

24 coal-fired plant would emit approximately 446 tons (405 MT) per year of particulate matter 

25 having an aerodynamic diameter less than, or equal to, 10 microns (PM10) annually. In addition, 

26 coal burning would also result in approximately 223 tons (202 MT) of particulate matter with an 

27 aerodynamic diameter of 2.5 microns or less (PM2.5). Coal-handling equipment would introduce 

28 fugitive dust emissions when fuel is being transferred to onsite storage and then reclaimed from 

29 storage for use in the plant.

30 During the construction of a coal-fired plant, onsite activities would also generate fugitive dust. 

31 Vehicles and motorized equipment would create exhaust emissions during the construction 

32 process. These impacts would be intermittent and short-lived; however, to minimize dust 

33 generation, construction crews would use applicable dust-control measures, as described 

34 above.

35 8.3.1.5 Carbon Monoxide

36 Based upon EPA emission factors (EPA 1998), the NRC staff estimates that total carbon 

37 monoxide emissions would be approximately 784 tons (711 MT) per year.

38 8.3.1.6 Conclusion

39 While the GElS analysis mentions global warming from carbon dioxide emissions and acid rain 

40 from sulfur and nitrogen oxide emissions as potential impacts, it does not quantify emissions 

41 from coal-fired power plants; however, the GElS analysis does imply that air impacts would be 

42 substantial (NRC 1996). The above analysis shows that emissions of air pollutants—including 

43 sulfur oxides, nitrogen oxides, carbon monoxide, particulates, and carbon dioxide—exceed 

44 those produced by the existing nuclear power plant, as well as those of the other alternatives 

45 considered in this section. The NRC analysis for a coal-fired alternative suggests that impacts 

46 from the coal-fired alternative would have clearly noticeable effects, but given existing regulatory 
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1 regimens, permit requirements, and emissions controls, the coal-fired alternative would not 

2 destabilize air quality. Based on this information, the overall air quality impacts of a new 

3 coal-fired plant located at the STP site would be MODERATE.

4 8.3.2 Surface Water Resources

5 STPNOC did not propose using any surface water during the construction of Units 3 and 4 

6 (NRC 2011). As a new coal-fired plant would occupy a smaller footprint relative to new nuclear 

7 units, its construction would enable less extensive excavation and earthwork than new nuclear 

8 units. 

9 However, onsite construction of an engineered solid waste disposal facility (landfill), totaling 

10 200 ac (80 ha), would also be required for disposal of coal ash and air pollution control scrubber 

11 sludge from 20 years of operations. The combined acreage of the coal-fired plant and ash 

12 disposal facility would slightly exceed that required for the new nuclear generation alternative. 

13 Nevertheless, NRC would still expect that surface water would not be used to support 

14 construction activities under this alternative.

15 As for the aforementioned replacement-power alternatives, some temporary impacts to surface 

16 water quality may result from dredging activities in the Colorado River near the barge slip and 

17 from increased sediment loading in stormwater runoff from active construction areas. Due to 

18 the short-term nature of the dredging activities, the hydrologic alterations and sedimentation 

19 would be localized and temporary. Dredging would also be conducted under a permit from the 

20 USACE requiring the implementation of BMPs to minimize impacts. Runoff from construction 

21 areas, including construction of the disposal facility, would be controlled under a State-issued 

22 TPDES general permit that would require implementation of a stormwater pollution prevention 

23 plan and associated BMPs to prevent or significantly mitigate soil erosion and contamination of 

24 stormwater runoff from construction activities.

25 During operations, the coal-fired alternative would require a similar amount of cooling water as 

26 STP, Units 1 and 2. Because a similar amount of cooling water would be required, NRC 

27 expects that the existing intake and discharges on the MCR and the Colorado River would be 

28 sufficient to support this alternative. Surface water withdrawals would be subject to, and would 

29 remain well within, STPNOC’s existing water rights, and effluent discharges and stormwater 

30 discharges associated with industrial activity would be subject to a revised State-issued TPDES 

31 permit under this alternative. In accordance with the applicable TPDES permit, implementation 

32 of a stormwater pollution prevention plan for industrial activities would address stormwater 

33 run-on and runoff issues associated with coal storage and handling, as well as other stockpiles 

34 (e.g., lime) at the plant. These requirements would also encompass the handling, storage, and 

35 disposal of coal ash and scrubber wastes so as to mitigate the potential water quality impacts of 

36 contaminated runoff and infiltration.

37 In consideration of the information above, the impacts on surface water use and quality from 

38 construction and operations under the coal-fired generation alternative would be SMALL.

39 8.3.3 Groundwater Resources

40 Construction-related ground disturbance and excavation work would be somewhat less than 

41 that described for the new nuclear alternative, mainly due to a reduction in deep excavation 

42 work and less intensive structural work. However, construction and excavation for a coal ash 

43 and scrubber residue disposal facility would have additional potential impacts on groundwater. 

44 Although groundwater dewatering of foundation excavations for a new coal-fired plant would 

45 likely be required, slurry walls and wells were proposed for use to minimize potential adverse 
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1 effects from dewatering both on site and off site (NRC 2011). Construction of the coal ash and 

2 scrubber residue disposal facility would have to be carefully managed and sited to minimize the 

3 need for construction dewatering due to the shallow depth of groundwater across many areas of 

4 the STP site. Application of BMPs in accordance with a state-issued NPDES general permit, 

5 including appropriate waste management and spill prevention practices, would prevent or 

6 minimize groundwater quality impacts during construction.

7 STPNOC assumed that a fossil-fuel-fired generation facility would be located adjacent to the 

8 STP, Units 1 and 2, site to use the existing infrastructure, including continued use of the existing 

9 onsite groundwater production wells at STP. Groundwater use for construction of a new 

10 coal-fired plant is expected to be similar to the volume required for new nuclear units under this 

11 alternative. This would encompass such uses as potable and sanitary uses, concrete 

12 production, dust suppression and soil compaction, and other uses.

13 For coal-fired plant operations, NRC assumed that the coal-fired generation alternative would 

14 entail the same relative ratio of groundwater use to surface water use as that used at STP, 

15 Units 1 and 2. This includes the use of groundwater for freshwater and service water makeup, 

16 potable and sanitary uses, and fire protection. It is expected that total groundwater usage and 

17 associated aquifer effects would likely be less than those under current STP operations. This is 

18 because of the fewer number of auxiliary systems requiring groundwater and the smaller 

19 workforce under the coal-fired generation alternative.

20 Disposal of coal ash and air pollution control scrubber wastes in an onsite landfill would have 

21 the potential to impact groundwater quality due to the generation and infiltration of leachate to 

22 the environment. NRC assumes that any disposal facility would incorporate a liner to prevent 

23 infiltration and would be operated with a leachate monitoring and collection system and ambient 

24 groundwater monitoring system. These systems and measures would ensure that facility 

25 operations would not impact groundwater quality. Operation of the facility would also be subject 

26 to a state-issued landfill permit.

27 Based on this information, the overall impact on groundwater use and quality from construction 

28 and operations under the coal-fired generation alternative would be SMALL.

29 8.3.4 Aquatic Ecology

30 Construction activities for the coal-fired alternative (such as construction of heavy haul roads 

31 and the power blocks) could affect drainage areas or other onsite aquatic features due to site 

32 runoff. NRC assumed that the plant operator would install temporary and permanent erosion 

33 and sediment control measures to minimize the flow of disturbed soils into ditches and 

34 wetlands. Such BMPs would likely be described in a TPDES general permit relating to 

35 stormwater discharges for construction activities. To bring new materials to the site, NRC 

36 assumed the plant operator would dredge near the barge slip to transport some materials using 

37 barges. Permits and certifications from the USACE and other agencies would require the 

38 implementation of BMPs to minimize impacts. Due to the short-term nature of the dredging 

39 activities, the hydrological alterations to aquatic habitats would be localized and temporary.

40 During operations, the coal-fired alternative would require a similar amount of cooling water to 

41 be withdrawn from the Colorado River at STP, Units 1 and 2, and the thermal discharge would 

42 also be similar to STP, Units 1 and 2. Therefore, the number of fish and other aquatic 

43 organisms affected by impingement, entrainment, and heat shock would be similar for a 

44 coal-fired alternative as for license renewal. The cooling system for a new coal-fired plant would 

45 have similar chemical discharges as STP, but the air emissions from the coal-fired plant would 

46 emit particulates that would settle onto the river surface and introduce a new source of 

47 pollutants that would not exist if STP continued operating. However, the flow of the Colorado 
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1 River would dissipate pollutants, which would decrease the concentration of pollutants and 

2 minimize the exposure of fish and other aquatic organisms to pollutants.

3 Construction activities would require BMPs; dredging would be short-term; the surface water 

4 withdrawal and discharge for this alternative would be less than for STP, Units 1 and 2; and 

5 pollutants would dissipate with the Colorado River (minimizing exposure concentrations to 

6 aquatic resources). Therefore, impacts on aquatic ecology would be SMALL.

7 8.3.5 Terrestrial Ecology

8 Coal-fired operations would affect terrestrial ecology both on the STP site and in offsite coal 

9 mining areas.

10 If the coal-fired alternative is constructed at the STP site, construction would likely affect a 

11 variety of habitats and land uses, including industrial land (buildings, parking areas, and 

12 mowed-maintained fields), drainage ditches, scattered small palustrine wetlands, scrub-shrub 

13 habitat, and mixed grassland habitat where abandoned farm lands previously existed prior to 

14 construction of Units 1 and 2. Most of these areas have been mildly to extensively disturbed 

15 during the construction and operations of Units 1 and 2 and other human activities. After the 

16 completion of the new units, construction crews would likely grade, landscape, and replant the 

17 areas used for temporary building support, which is similar to what STPNOC proposed to do 

18 after completion of proposed new nuclear Units 3 and 4 (STPNOC 2010b). The majority of 

19 permanently affected areas would be maintained (e.g., mowed) and industrial areas. The plant 

20 operator would likely implement BMPs to minimize impacts to wetlands. The plant operator 

21 would be required to comply with the USACE’s 404 permits. Construction activities could also 

22 adversely affect onsite wildlife through noise, increased light pollution, and increased traffic. 

23 However, these impacts would be temporary and minor.

24 Coal mining would affect terrestrial resources at offsite coals mines, although much of this land 

25 is likely already disturbed by mining, and the incremental effects of this alternative on coal mine 

26 terrestrial ecology are difficult to gauge.

27 STPNOC estimates that 253,000 tons of coal ash and 88,000 tons of scrubber sludge would be 

28 disposed of on site annually (STPNOC 2010a). Over a 40-year period, this would require 

29 approximately 200 ac for land disposal (STPNOC 2010a). As described above, these areas 

30 could affect terrestrial ecology, especially if they are located in habitats that are currently used 

31 by wildlife on the STP site. Once the disposal area is reclaimed, the habitats may be useable 

32 by wildlife that inhabits open areas.

33 Deposition of acid rain resulting from nitrogen or sulfur oxide emissions, and the deposition of 

34 other pollutants, can also affect terrestrial ecology both on and off site. Given the emission 

35 regulations discussed in Section 8.3.1, air deposition impacts may be noticeable but are unlikely

36 to be destabilizing.

37 Because of the potential habitat disturbances and potential pollutant deposition, impacts to 

38 terrestrial resources from a coal-fired alternative would be MODERATE.

39 8.3.6 Human Health

40 Coal-fired power plants introduce worker risks from coal and limestone mining, coal and 

41 limestone transportation, plant operations, and disposal of coal combustion and scrubber 

42 wastes. In addition, there are public risks from the inhalation of stack emissions (as addressed 

43 in Section 8.3.1) and the secondary effects of eating foods grown in areas subject to deposition 

44 from plant stacks.
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1 Human health risks of coal-fired power plants are described, in general, in Table 8–2 of the 

2 GEIS (NRC 1996). Cancer and emphysema, as a result of the inhalation of toxins and 

3 particulates, are identified as potential health risks to occupational workers and members of the 

4 public (NRC 1996). The human health risks of coal-fired power plants, both to occupational 

5 workers and to members of the public, are greater than those of the current STP due to 

6 exposures to chemicals such as mercury; sulfur oxides; nitrogen oxides; radioactive elements, 

7 such as uranium and thorium contained in coal and coal ash; and polycyclic aromatic 

8 hydrocarbon (PAH) compounds, including benzo(a)pyrene.

9 Regulations restricting emissions—enforced by EPA or state agencies—have acted to 

10 significantly reduce potential health effects but do not entirely eliminate them. These agencies 

11 also impose site-specific emission limits as needed to protect human health. Even if the 

12 coal-fired alternative were located in a non-attainment area, emission controls and trading or 

13 offset mechanisms could prevent further regional degradation; however, local effects could be 

14 visible. Many of the byproducts of coal combustion responsible for health effects are largely 

15 controlled, captured, or converted in modern power plants (as described in Section 8.3.1), 

16 although some level of health effects may remain.

17 Aside from emission impacts, the coal-fired alternative introduces the risk of coal pile fires, and 

18 for those plants that use coal combustion liquid and sludge waste impoundments, the release of 

19 the waste due to a failure of the impoundment. Although there have been several instances of 

20 this occurring in recent years, these types of events are still relatively rare.

21 Despite the range of potential threats to human health, extensive health-based regulations exist 

22 to mitigate the risks to workers and the public. As a result, the NRC staff expects human health 

23 impacts to be characterized as SMALL.

24 Noise during construction activities and from plant operations may be detectable off site. The 

25 plant operator would need to adhere to local ordinances regarding maximum noise levels during 

26 construction and operations. Therefore, impacts from noise would likely be SMALL.

27 8.3.7 Land Use

28 The GEIS generically evaluates the impact of constructing and operating various replacement 

29 power plant alternatives on land use, both on and off each plant site. The analysis of land use 

30 impacts focuses on the amount of land area that would be affected by the construction and 

31 operation of a supercritical coal-fired generation at the STP site.

32 Based on scaled GEIS estimates, the plant would require approximately 4,629 ac (1,873 ha) of 

33 land. STPNOC estimates that 353 ac (143 ha) of land would be required (STPNOC 2010a). 

34 This estimate appears reasonable; therefore, it is used for this analysis. STPNOC estimates 

35 that an additional 200 ac (80 ha) of land area would be required on site for waste disposal 

36 (STPNOC 2010a). Land would also be required on site for frequent coal and limestone 

37 deliveries by rail or barge.

38 Offsite land use impacts would occur from coal mining, in addition to land use impacts from the 

39 construction and operation of the new power plant. Scaling from GEIS estimates, approximately 

40 59,906 ac (24,244 ha) of land could be affected by mining coal and waste disposal to support 

41 the coal-fired alternative during its operational life (NRC 1996); however, most of the land in 

42 existing coal mining areas has already experienced some level of disturbance. The elimination 

43 of the need for uranium mining to supply fuel for the STP would partially offset this offsite land 

44 use impact. Scaling from GEIS estimates, approximately 2,560 ac (1,036 ha) would not be 

45 needed for mining and processing uranium during the operating life of the plant.
Environmental Impacts of Alternatives

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1 Since a substantial amount of onsite land at the STP site would be converted for coal and 

2 limestone delivery and waste disposal, land use impacts would be MODERATE. 

3 8.3.8 Socioeconomics

4 As previously discussed, socioeconomic impacts are defined in terms of changes to the 

5 demographic and economic characteristics and social condition of a region. For example, the 

6 number of jobs created by the construction and operation of a power plant could affect regional 

7 employment, income, and expenditures. Two types of jobs would be created by this alternative: 

8 (1) construction jobs, which are transient, short in duration, and less likely to have a long-term 

9 socioeconomic impact; and (2) power plant operation jobs, which have the greater potential for 

10 permanent, long-term socioeconomic impacts. Workforce requirements of power plant 

11 construction and operation for the coal-fired alternative were determined to measure their 

12 possible effects on current socioeconomic conditions.

13 Scaling from GEIS estimates, the construction workforce would peak at 6,808 workers. 

14 STPNOC projected a peak construction workforce of 3,955 employees (STPNOC 2010a). 

15 STPNOC’s estimate appears reasonable; therefore, it is used in this analysis. The relative 

16 economic impact of this many workers on the local economy and tax base would vary, with the 

17 greatest impacts occurring in the communities where the majority of construction workers would 

18 reside and spend their income. As a result, local communities could experience a short-term 

19 “boom” from increased tax revenue and income generated by construction expenditures and the 

20 increased demand for temporary (rental) housing and business services. Some construction 

21 workers could relocate to Matagorda and surrounding counties in order to be closer to the 

22 construction work site. However, given the proximity of STP to the Houston metropolitan area, 

23 many construction workers could commute to the STP site, thereby lessening the need for 

24 additional rental housing near STP. 

25 After completing the installation of the supercritical coal-fired power plant, local communities 

26 could experience a return to pre-construction economic conditions. Based on this information, 

27 and given the number of workers, socioeconomic impacts during construction in communities 

28 near the STP site could range from SMALL to MODERATE.

29 Scaling from GEIS estimates, the plant operation workforce would be 681 workers. STPNOC 

30 estimated a plant operation workforce of approximately 348 workers. The STPNOC estimate 

31 appears to be reasonable and is consistent with trends toward lowering labor costs by reducing 

32 the size of plant operations workforces. The amount of property taxes paid under the coal-fired 

33 alternative may increase if additional land is required off site to support this alternative. 

34 Socioeconomic impacts during operations could range from SMALL to MODERATE as the STP 

35 site transitions to the new supercritical coal-fired power plant. The potential reduction in overall 

36 employment at STP could affect property tax revenue and income in local communities and 

37 businesses. In addition, the permanent housing market could also experience increased 

38 vacancies and decreased prices if operations workers and their families move out of the region.

39 8.3.9 Transportation

40 Transportation impacts associated with construction and operation of a four-unit, coal-fired plant 

41 would consist of commuting workers and truck deliveries of construction materials to the STP 

42 site. During periods of peak construction activity, up to 3,955 workers could be commuting daily 

43 to the site (STPNOC 2010a). Workers commuting to the STP site would primarily use two-lane 

44 roads. The volume of traffic on these roads, especially FM 521, would increase substantially. 

45 In addition to commuting workers, trucks would be transporting construction materials and 

46 equipment to the worksite, thus increasing the amount of traffic on local roads. The increase in 
Environmental Impacts of Alternatives

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1 vehicular traffic would peak during shift changes, resulting in temporary levels of service 

2 impacts and delays at intersections. Some power plant components and materials could also 

3 be delivered by train or barge. Train deliveries could cause additional traffic delays at railroad 

4 crossings. Based on this information, traffic-related transportation impacts during construction 

5 could range from MODERATE to LARGE. 

6 Traffic-related transportation impacts would be greatly reduced after completing the installation 

7 of the coal-fired units. Transportation impacts would include daily commuting by the operating 

8 workforce, equipment and materials deliveries, and the removal of commercial waste material to 

9 offsite disposal or recycling facilities by truck. During operations, the estimated number of 

10 operations workers commuting to and from the STP site would be 348 workers. Frequent 

11 deliveries of coal and limestone by rail would add to the overall transportation impact by causing 

12 traffic delays at railroad crossings. Onsite coal storage would make it possible to receive 

13 several trains per day. Limestone delivered by rail could also add additional traffic (though 

14 considerably less traffic than that generated by coal deliveries). Traffic-related transportation 

15 impacts would be considerably less than current operations because the new supercritical

16 coal-fired power plant would employ far fewer workers than STP, Units 1 and 2. Overall, 

17 transportation impacts would be SMALL during power plant operations.

18 8.3.10 Aesthetics

19 The analysis of aesthetic impacts focuses on the degree of contrast between the coal-fired 

20 alternative and the surrounding landscape and the visibility of the coal-fired power plant. During 

21 construction, all of the clearing and excavation would occur on the STP site. These activities 

22 may be visible from offsite roads, particularly FM 521. Since the STP site already appears 

23 industrial, construction of the coal-fired power plant would appear similar to onsite activities 

24 during refueling outages.

25 The coal-fired alternative would be up to 200 ft (61 m) tall with an exhaust stack up to 500 ft 

26 (152 m), which may be visible off site in daylight hours. The coal-fired plant, however, would be 

27 shorter and less noticeable than the current STP reactor building, which has a height of 

28 approximately 250 ft (76 m) (STPNOC 2010b). Lighting on plant structures may be detectable 

29 off site. Noise generated during power plant operations would be limited to routine industrial 

30 processes and communications.

31 In general, given the industrial appearance of the STP site, the new coal-fired power plant would 

32 blend in with the surroundings if the existing STP, Units 1 and 2, remains. Aesthetic changes 

33 would be limited to the immediate vicinity of the existing STP site, and any impacts would be 

34 SMALL.

35 8.3.11 Historic and Archaeological Resources

36 The same considerations, discussed in Section 8.1.11, for the impact of the construction of a 

37 new nuclear plant on historic and archaeological resources apply to the construction activities 

38 that would occur on the STP site for a coal-fired plant. As described in Section 2.2.10, much of 

39 the STP site has been previously disturbed by the construction of STP, Units 1 and 2. In 

40 addition, in preparation for the COL application for Units 3 and 4, STPNOC conducted a cultural 

41 resources assessment of the STP site. STPNOC reviewed existing information for the STP site 

42 and the area within a 10-mi (16-km) radius. STPNOC concluded that any cultural resource sites 

43 that may have existed on site would no longer retain their integrity because the area was heavily 

44 disturbed during the construction of Units 1 and 2 (STPNOC 2010b). In December 2006, 

45 STPNOC reported these findings to the SHPO at the Texas Historical Commission. The SHPO 
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1 concurred, in January 2007, that there would be no impacts to historic properties 

2 (STPNOC 2006; THC 2007).

3 There is a low potential for cultural resources to be located in previously undisturbed portions of 

4 the STP site. However, if the coal-fired units were to be sited within undisturbed areas or within 

5 areas of known cultural sensitivity (historic grave site located on the property and described in 

6 Section 2.2.10), these areas would need to be surveyed by a professional archaeologist to 

7 identify and develop possible mitigation measures to address any adverse effects from project 

8 activities. NRC assumes the plant operator would follow similar procedures to those described 

9 in the final EIS for STP, Units 3 and 4 (NRC 2011), if the plant operator discovered any historic 

10 or cultural resources during ground-disturbing activities associated with building the new units.

11 The NRC staff determined that the impact of the coal-fired alternative at the STP site on historic 

12 and archaeological resources would be SMALL for the following reasons:

13 • NRC (2011) and STPNOC (2010a, 2010b) did not identify any cultural 

14 resources that could be affected by Units 3 and 4. 

15 • The SHPO determined that construction for Units 3 and 4 would not affect 

16 cultural and historic resources. 

17 • NRC assumes that the plant operator would follow environmental compliance 

18 procedures for new ground-disturbing activities.

19 8.3.12 Environmental Justice

20 The environmental justice impact analysis evaluates the potential for disproportionately high and 

21 adverse human health, environmental, and socioeconomic effects on minority and low-income 

22 populations that could result from the construction and operation of a new power plant. As 

23 previously discussed in Section 8.1.12, such effects may include human health, biological, 

24 cultural, economic, or social impacts. Some of these potential effects have been identified in 

25 resource areas discussed in this SEIS. For example, increased demand for rental housing 

26 during plant construction could disproportionately affect low-income populations. Minority and 

27 low-income populations are subsets of the general public residing in the vicinity of the STP site, 

28 and all are exposed to the same hazards generated from constructing and operating a new 

29 coal-fired plant. Section 4.9.7, “Environmental Justice,” presents demographic information 

30 about minority and low-income populations residing in the vicinity of the STP site. 

31 Potential impacts to minority and low-income populations from the construction and operation of 

32 a new coal-fired plant at the STP site would mostly consist of environmental and socioeconomic 

33 effects (e.g., noise, dust, traffic, employment, and housing impacts). Noise and dust impacts 

34 during construction would be short-term and primarily limited to onsite activities. Minority and 

35 low-income populations residing along site access roads would be directly affected by increased 

36 commuter vehicle and truck traffic. However, because of the temporary nature of construction, 

37 these effects would only occur during certain hours of the day and are unlikely to be high and 

38 adverse. Increased demand for rental housing during construction could affect low-income 

39 populations living near STP. However, given the proximity of the STP site to the Houston 

40 metropolitan areas, many construction workers could commute to the STP site, thereby 

41 lessening the additional need for rental housing.

42 Based on this information, and the analysis of human health and environmental impacts 

43 presented in this SEIS, the construction and operation of a new coal-fired power plant would not 

44 have disproportionately high and adverse human health and environmental effects on minority 

45 and low-income populations residing in the vicinity of the STP site. 
Environmental Impacts of Alternatives

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1 8.3.13 Waste Management

2 During the construction stage of the coal-fired alternative, land clearing and other construction 

3 activities would generate waste that could be recycled, disposed of on site, or shipped to an 

4 offsite waste disposal facility. Because the alternative would be constructed on or near the 

5 previously disturbed STP site, the amounts of waste produced during land clearing would be 

6 reduced.

7 Coal combustion generates several waste streams including ash (a dry solid) and sludge (a 

8 semi-solid by-product of emission control system operation). This coal-fired alternative would 

9 produce roughly 446,000 tons (405,000 MT) of ash, and 43 percent (193,000 tons 

10 (175,000 MT)) of the ash would be recycled for beneficial use (STPNOC 2010a). 

11 STPNOC (2010a) estimated that approximately 88,000 tons (80,000 MT) of scrubber sludge 

12 would be disposed of on site each year, which was based on an assumed annual lime usage of 

13 approximately 107,000 tons (97 MT). Approximately 200 ac (81 ha) would be required to 

14 dispose of the ash and scrubber waste on site over a 40-year plant life (STPNOC 2010a). All 

15 waste disposal would occur on site.

16 The impacts from waste generated during operation of this coal-fired alternative would be 

17 MODERATE because the impacts would be clearly visible but would not destabilize important 

18 resources.

19 8.3.14 Summary of Impacts for the Supercritical Coal-Fired Generation Alternative

20 Table 8–4 provides a summary of the environmental impacts of the supercritical coal-fired 

21 alternative compared to continued operation of STP.

22 Table 8–4. Summary of Environmental Impacts of the Supercritical Coal-Fired 

23 Alternative Compared to Continued Operation of STP, Units 1 and 2 

Supercritical Coal-Fired 

Generation Continued STP Operation

Air quality MODERATE SMALL

Surface water SMALL SMALL

Groundwater SMALL SMALL

Aquatic resources SMALL SMALL

Terrestrial resources MODERATE SMALL

Human health SMALL SMALL to MODERATE

Land use MODERATE SMALL

Socioeconomics SMALL to MODERATE SMALL

Transportation SMALL to LARGE SMALL

Aesthetics SMALL SMALL

Historic & archaeological SMALL SMALL

Waste management MODERATE SMALL
Environmental Impacts of Alternatives

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8.4

2 In this section, the NRC staff evaluates the environmental impacts of a combination of 

3 alternatives. This combination includes 640 MWe supplied by one NGCC unit similar to the 

4 units identified in Section 8.2, 1,620 MWe supplied by wind energy projects, and 300 MWe of 

5 energy conservation and efficiency (also known as demand-side management). Because wind 

6 is an intermittent resource, wind energy projects would be interconnected to one another on the 

7 transmission grid, and the NGCC unit could be used, if needed, to be a baseload resource. 

8 Interconnecting wind farms through the transmission grid increase the probability that at least 

9 one site experiences sufficient wind to produce electricity. Thus, as more sites are added to the 

10 transmission grid, the interconnected wind farms provide electricity that is comparable to a 

11 single wind farm providing near constant deliverable wind power. Archer and Jacobson (2007) 

12 looked at 19 wind energy sites in the southeast, including 2 sites in Texas, and determined that 

13 the 19 interconnected wind farms could guarantee 312 kWe of power for 79 percent of time. 

14 Based on this data, NRC assumed that to provide 1,620 MWe of wind energy, the installed 

15 capacity would need to be at least 7,714 MWe. NRC included this contribution from wind power 

16 because Texas has significant wind energy resources and leads the Nation in wind-powered 

17 generation capacity. As of June 30, 2011, the installed wind capacity in Texas was 

18 10,135 MWe (DOE 2011b). In addition, wind energy projects totaling 36,124 MWe are currently 

19 under ERCOT’s review (ERCOT 2011a), and the installed wind capacity in Texas has been 

20 increasing annually by 500 MWe to 3,000 MWe in each of the past 7 years (DOE 2011b). 

21 Therefore, NRC considers 1,620 MWe of wind energy (with an installed capacity of 7,714 MWe) 

22 to be a reasonable amount by the time the STP licenses expire in 2027 and 2028. Section 8.6.3 

23 discusses the status of wind energy technology and implementation in greater detail.

1 Combination Alternative

24 NRC assumed that one new NGCC unit of the type described in Section 8.2 would be 

25 constructed and installed at the STP site with a total capacity of 640 MWe. The appearance of 

26 an NGCC unit would be similar to that of the full NGCC alternative considered in Section 8.2, 

27 although only one unit would be constructed. The NRC estimates that it would require about 

28 one-fourth of the space necessary for the alternative considered in Section 8.2 and that 

29 construction and operational effects would scale accordingly.

30 NRC assumed that the wind turbines could be constructed at multiple sites scattered over large 

31 distances to minimize the likelihood that all sites would be exposed to the same weather events 

32 at the same time. Some of these sites could potentially be offshore, although no turbines 

33 currently operate offshore anywhere in the U.S. NRC assumed that the contribution from 

34 offshore wind energy would be relatively small because offshore wind capacity of the magnitude 

35 analyzed in this alternative exceeds by a factor of 10 or more the amount of offshore wind 

36 projected by the EIA for the entire U.S. by the year 2035 (EIA 2011a). Assuming each turbine 

37 has a capacity of 2 MWe, construction and operation of approximately 3,877 turbines would be 

38 required. In addition, new transmission lines would likely be needed to connect the wind energy 

39 projects to one another and the distribution system.

40 STPNOC estimated that a utility-scale wind plant requires 60 ac of land per MWe of installed 

41 capacity in open, flat terrain (STPNOC 2010a). Approximately 462,900 ac (187,300 ha) of land 

42 would be required for the installed capacity of 7,714 MWe. A small percentage of this area 

43 would be occupied by turbines, access roads, and other infrastructure, with the rest of the area 

44 potentially available for compatible other uses, such as agriculture. For example, NREL (2009) 

45 estimates that 0.7 ha (1.7 ac) of land would be temporarily disturbed per MWe of installed 

46 capacity and that 0.3 ha (0.7 ac) of land would be permanently disturbed per MWe of installed 

47 capacity. For this alternative, approximately 2,185 ac (884 ha) would be temporarily disturbed, 

48 and 937 ac (379 ha) would be permanently disturbed.
Environmental Impacts of Alternatives

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1 For the combination alternative, the NRC assumed that an Energy Efficiency and Conservation 

2 Program would replace 300 MWe of current STP output. As discussed in Section 8.6.2, 

3 beginning in 2009, all electric transmission and distribution utilities within the ERCOT market—

4 including CPS Energy and Austin Energy (two of the owners of STP, Units 1 and 2)—were 

5 required to implement energy efficiency and conservation programs to reduce their customers’ 

6 energy consumption by a minimum of 20 percent of the utility’s annual growth in 2009, 

7 25 percent in 2012, and 30 percent in 2013 and beyond. CPS Energy and Austin Energy 

8 currently implement programs to promote energy efficiency and conservation. The 300 MWe

9 reduction in energy use for this alternative would be beyond the required energy efficiency and 

10 conservation programs currently implemented by CPS Energy and Austin Energy. No major 

11 construction would be necessary for the energy efficiency and conservation component of the 

12 combination alternative.

13 8.4.1 Air Quality

14 As discussed in Section 2.2.2.1, the STP site is located in central Matagorda County, Texas, at 

15 the southern edge of the Metropolitan Houston–Galveston Intrastate Air Quality Control Region 

16 (40 CFR 81.38). The Corpus Christi–Victoria Intrastate Air Quality Control Region 

17 (40 CFR 81.136) lies immediately south and west of Matagorda County. EPA has designated 

18 all of the counties in these Air Quality Control Regions adjacent to the STP site as in compliance 

19 with the National Ambient Air Quality Standards (40 CFR 81.344) except Brazoria County to the 

20 north; Brazoria County is classified Nonattainment/Severe relative to the 8-hour ozone standard 

21 (EPA 2011b).

22 Construction activities for both the NGCC plant and wind energy components would cause 

23 some localized temporary air quality effects because of equipment emissions and fugitive dust 

24 from operation of earth-moving and material-handling equipment. Emissions from workers’ 

25 vehicles and motorized construction equipment exhaust would be temporary. NRC assumed 

26 that construction crews would use dust-control practices to control and reduce fugitive dust 

27 because § 111.145 of TCEQ’s regulations require dust suppression control during the 

28 construction of facilities and parking lots. Impacts from wind turbine installation would be 

29 spread across multiple locations, but these impacts would be short in duration. In its 

30 programmatic final EIS, which analyzed the impacts of offshore wind projects generically within 

31 U.S. waters, U.S. Minerals Management Service (MMS, which is currently Bureau of Ocean 

32 Energy Management) determined that construction of offshore wind projects could result in air 

33 quality impacts, mainly from fugitive dust emissions, and emissions of sulfur dioxide and ozone 

34 precursors (MMS 2007).

35 New air emission sources in Texas must comply with Federal, Texas, and local air quality 

36 control laws. The NGCC component of this combination alternative would qualify as a new 

37 major-emitting industrial facility and would be subject to PSD requirements under CAA 

38 (EPA 2011c). The NGCC unit would need to comply with the standards of performance for 

39 electric utility steam generating units set forth in 40 CFR Part 60 Subpart KKKK. The plant 

40 would also require an operating permit from TCEQ.

41 Subpart P of 40 CFR Part 51 contains the visibility protection regulatory requirements, including 

42 the review of new sources that would be constructed in the attainment or unclassified areas and 

43 may affect visibility in any Federal Class I area. If an NGCC plant was located close to a 

44 mandatory Class I area, additional air pollution control requirements would be required. As 

45 noted in Section 2.2.2.1, there are no mandatory Class I Federal areas within 50 mi of the STP 

46 site.
Environmental Impacts of Alternatives

8-41

1 The NRC projects the following emissions, assuming a maximum of 640 MWe power from the 

2 NGCC component of this combination alternative based on data published by the EIA, EPA, and 

3 on performance characteristics and emissions controls:

4 • sulfur oxides—50 tons (46 MT) per year, 

5 • nitrogen oxides—219 tons (199 MT) per year, 

6 • carbon dioxide—1,727,000 tons (1,567,000 MT) per year, 

7 • carbon monoxide—222 tons (201 MT) per year, 

8 • TSP—97 tons (88 MT) per year, and

9 • particulate matter PM10—97 tons (88 MT) per year. 

10 During operations, the wind energy projects would not produce emissions. However, workforce 

11 transportation and eventual decommissioning could result in carbon dioxide emissions.

12 For the Energy Efficiency and Conservation Program, the GEIS notes that the environmental 

13 impacts are likely to be centered on indoor air quality (NRC 1996). This is due to increased 

14 weatherization of the home in the form of extra insulation and reduced air turnover rates from 

15 the reduction in air leaks. However, the actual impact is highly site-specific and not yet 

16 well-established.

17 8.4.1.1 Sulfur Oxide and Nitrogen Oxide

18 The new NGCC plant would have to comply with Title IV of the CAA (42 USC 7651) reduction 

19 requirements for sulfur and nitrogen oxides, which are the main precursors of acid rain and the 

20 major cause of reduced visibility. Title IV establishes maximum sulfur and nitrogen oxide

21 emission rates from existing plants and a system of sulfur oxide emission allowances that can 

22 be used, sold, or saved for future use by new plants. In addition, in August 2011, EPA 

23 published the Cross-State Air Pollution Rule, which included reductions of sulfur and nitrogen 

24 oxides in Texas. According to the rule, NGCC plants would need to comply with the new 

25 reductions by 2012.

26 As stated above, the new NGCC plant would produce 50 tons (46 MT) per year of sulfur oxides 

27 and 219 tons (199 MT) per year of nitrogen oxides based on the use of the dry low-nitrogen 

28 oxide combustion technology and use of SCR to significantly reduce nitrogen oxide emissions. 

29 The new plant would be subjected to the continuous monitoring requirements for sulfur and 

30 nitrogen oxides. The current SIP for Texas includes a Cap and Trade Program for sulfur and 

31 nitrogen oxide emissions. To operate the NGCC plant, the plant operator would have to 

32 purchase sulfur dioxide allowances from the open market or shut down existing fossil-fired 

33 plant(s) and apply the credits to the new plant (STPNOC 2010a). Thus, provided the plant 

34 operator is able to purchase sufficient allowances to operate, the NGCC portion of this 

35 alternative would not add to net regional sulfur dioxide or nitrogen oxide emissions, although it 

36 might do so locally.

37 8.4.1.2 Greenhouse Gases

38 The new plant would release greenhouse gases, such as carbon dioxide and methane. The 

39 plant would be subjected to the continuous monitoring requirements for carbon dioxide, as 

40 specified in 40 CFR Part 75. The NGCC plant would emit approximately 1.7 million tons

41 (approximately 1.6 million MT) per year of carbon dioxide emissions.

42 On July 12, 2012, EPA issued a final rule tailoring the applicability criteria that determine which

43 stationary sources and modification to existing projects become subject to permitting 

44 requirements for greenhouse emissions under the PSD and Title V Programs of the CAA
Environmental Impacts of Alternatives

8-42

1 (77 FR 41051). According to the Tailoring Rule, greenhouse gases are a regulated new source 

2 review pollutant under the PSD major source permitting program if the source is otherwise 

3 subject to PSD (for another regulated new source review pollutant) and has a greenhouse gas 

4 potential to emit equal to or greater than 75,000 tons (68,000 MT) per year of carbon dioxide 

5 equivalent (“carbon dioxide equivalent” adjusting for different global warming potentials for 

6 different greenhouse gases). Such sources would be subject to BACT, although EPA has yet to 

7 determine BACT for greenhouse gases.

8 EPA issued a FIP on May 3, 2011, to permit greenhouse gas-emitting sources in states that do 

9 not have measures to lower greenhouse gases in their SIP. Because Texas has not updated its 

10 SIP to include greenhouse gases, EPA will be the official permitting authority for greenhouse 

11 gas-emitting sources in Texas if the SIP is not updated before the NGCC plant begins 

12 operations.

13 8.4.1.3 Particulates

14 The new NGCC plant would produce 97 tons (88 MT) per year of TSP, all of which would be 

15 emitted as PM10. STPNOC (2010a) indicated that all PM10 emissions would be PM2.5. 

16 DOE (2007) evaluated the emissions from a hypothetical 560 MWe NGCC unit using BACT to 

17 meet the emission requirements of the 2006 New Source Performance Standards. DOE 

18 concluded that emissions from particulates would be negligible because NGCC use natural gas 

19 as fuel; therefore, NGCC plants would not require emissions controls equipment or features to 

20 reduce these emissions.

21 8.4.1.4 Hazardous Air Pollutants

22 In December 2000, EPA issued regulatory findings (65 FR 79825) on emissions of HAPs from 

23 electric utility steam-generating units, which said that natural gas-fired plants emit HAPs such as 

24 arsenic, formaldehyde, and nickel, and stated the following: 

25 Also in the utility RTC (Report to Congress), the EPA indicated that the impacts 

26 due to HAP emissions from natural gas-fired electric utility steam generating 

27 units were negligible based on the results of the study. The Administrator finds 

28 that regulation of HAP emissions from natural gas-fired electric utility steam 

29 generating units is not appropriate or necessary.

30 As a result of EPA’s conclusion, the NRC staff finds no significant air quality effects from HAPs 

31 from the NGCC component of this alternative. The wind and energy efficiency and conservation 

32 components of this alternative release no HAPs.

33 8.4.1.5 Conclusion

34 Based on the NRC staff’s analysis, the overall air quality impacts of a combination alternative 

35 that includes a new NGCC plant located at the STP site, wind energy projects, and the Energy 

36 Efficiency and Conservation Program would be SMALL to MODERATE. Emissions from the 

37 wind energy projects and the Energy Efficiency and Conservation Program would not be 

38 noticeable. Emissions from the NGCC portion of this alternative would be noticeable for 

39 greenhouse gases; carbon dioxide emissions would be two orders of magnitude larger than the 

40 threshold in EPA’s tailoring rule for greenhouse gas (75,000 tons (68,000 MT) per year of 

41 carbon dioxide equivalent) that would trigger a regulated new source review. Impacts would not 

42 be noticeable for sulfur and nitrogen oxides because the Texas SIP requires a Cap and Trade 

43 Program, and there would be no net increase in sulfur and nitrogen oxide emissions. Based on 

44 analyses from DOE (2007) and EPA (2000, 65 FR 79825), TSPs and HAPs from the NGCC unit 

45 would have negligible impacts.
Environmental Impacts of Alternatives

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1 8.4.2 Surface Water Resources

2 STPNOC did not propose using any surface water during the construction of Units 3 and 4 

3 (NRC 2011). Because a single NGCC unit occupies a smaller footprint, and its construction 

4 would entail substantially less excavation and earthwork at the STP site as compared to Units 3 

5 and 4, NRC expects that surface water would not be used during construction for the NGCC 

6 component of this alternative.

7 As further described in Section 8.5.2 for the NGCC alternative, some temporary impacts to 

8 surface water quality may result from dredging activities in the Colorado River near the barge 

9 slip and from increased sediment loading in stormwater runoff from active construction areas. 

10 These activities would be conducted under a permit from the USACE requiring the 

11 implementation of BMPs to minimize impacts. Runoff from construction areas would be 

12 controlled under a State-issued TPDES general permit that would require implementation of a 

13 stormwater pollution prevention plan and associated BMPs.

14 Small amounts of water would be required during the construction phase for each of the 

15 3,877 wind turbines for dust suppression and compaction during site clearing and for concrete 

16 production for pad and piling construction, as appropriate. Although surface water from nearby 

17 water bodies may be used for pad site construction at some locations, it is likely that water 

18 would be procured from offsite sources and trucked to the point of use on an as needed basis. 

19 Use of ready-mix concrete would also reduce the need for onsite use of nearby water sources.

20 Further, the installation of land-based wind turbines would require installation of access roads 

21 and possibly transmission lines (especially for turbine sites not already proximal to transmission 

22 line corridors). Access road construction would also require some water for dust suppression 

23 and roadbed compaction and would have the potential to result in soil erosion and stormwater 

24 runoff from cleared areas. Water would likely be trucked to the point of use from offsite 

25 locations along with road construction materials. Construction activities would be conducted in 

26 accordance with State-issued TPDES or equivalent permits for stormwater discharges 

27 associated with construction activity, which would require the implementation of appropriate 

28 BMPs to prevent or mitigate water quality impacts.

29 Construction of offshore wind turbines, including the offshore foundation and pilings, associated 

30 anchoring devices, undersea cables, and onshore support installation (e.g., transformers) would 

31 also have the potential to cause water quality impacts due to soil and sediment erosion and 

32 runoff. Most notably, potential impacts would include disturbance of marine sediments from pile 

33 driving and erection of cofferdams for the wind turbine superstructures. Nevertheless, such 

34 water quality impacts would be temporary, and activities would be conducted in accordance with 

35 USACE and other applicable permits and requiring the use of BMPs to minimize impacts.

36 For facility operations, the NGCC component of this alternative would require about one-fourth 

37 of the water required by the NGCC alternative. It is expected that use of the existing intake and 

38 discharge infrastructure on the MCR and the Colorado River would be sufficient to support the 

39 NGCC plant. Surface water withdrawals would be subject to, and would remain well within, 

40 STPNOC’s existing water rights, and effluent discharges and stormwater discharges associated 

41 with industrial activity would be subject to a revised State-issued TPDES permit under this 

42 alternative. To support operations of individual wind turbine installations, only very small 

43 amounts of water would be used to periodically clean turbine blades and motors as part of 

44 routine servicing. It would be expected that water would be trucked to the point of use and 

45 procured from nearby sources.

46 Implementation of the Energy Efficiency and Conservation Program component of this 

47 alternative would likely entail little or no impact on surface water resources.
Environmental Impacts of Alternatives

8-44

1 In consideration of the information above, the impacts on surface water use and quality from 

2 construction and operations under the combination alternative would be SMALL.

3 8.4.3 Groundwater Resources

4 For the single NGCC plant at the STP site, construction-related ground disturbance and 

5 excavation work would be substantially less than that described for the NGCC alternative. 

6 Although groundwater dewatering of foundation excavations for a new NGCC plant would likely 

7 be required, slurry walls and wells were proposed for use to minimize potential adverse effects 

8 from dewatering both on site and off site (NRC 2011). Groundwater dewatering, where 

9 required, for installation of wind turbines on land, would be minimal due to the small footprint of 

10 foundation structures. For all construction activities, appropriate BMPs, including spill 

11 prevention practices, would be employed during wind turbine construction to prevent or 

12 minimize impacts on groundwater quality.

13 For NGCC plant operations, NRC assumed that the NGCC alternative would entail the same 

14 relative ratio of groundwater use to surface water use as that used at STP, Units 1 and 2. As 

15 such, for a single NGCC unit, groundwater use would be about one-fourth of the water required 

16 by the NGCC alternative and easily supported by existing onsite groundwater production wells

17 at STP. Little or no groundwater use would be expected for operation of wind turbines.

18 Implementation of the Energy Efficiency and Conservation Program component of this 

19 alternative would likely entail little or no impact on groundwater resources.

20 Based on this information, the overall impact on groundwater use and quality from construction 

21 and operations under the combination alternative would be SMALL.

22 8.4.4 Aquatic Ecology

23 Construction activities for the NGCC plant and land-based wind power projects (such as 

24 construction of heavy haul roads and support facilities) could affect drainage areas or other 

25 onsite aquatic features due to site runoff. NRC assumed that the plant operator would install 

26 temporary and permanent erosion and sediment control measures to minimize the flow of 

27 disturbed soils into ditches and wetlands. Such BMPs would likely be described in a TPDES 

28 general permit relating to stormwater discharges for construction activities.

29 To bring new materials to the STP site for the NGCC plant, NRC assumed the plant operator 

30 would dredge near the barge slip to transport some materials using barges. Permits and 

31 certifications from the USACE and other agencies would require the implementation of BMPs to 

32 minimize impacts. Due to the short-term nature of the dredging activities, the hydrological 

33 alterations to aquatic habitats would be localized and temporary.

34 During operations, the NGCC plant would require approximately one-fourth of the cooling water 

35 to be withdrawn from the Colorado River than the NGCC alternative analyzed in Section 8.2, 

36 and the thermal discharge would similarly be smaller. Therefore, the number of fish and other 

37 aquatic organisms affected by impingement, entrainment, and thermal impacts would be less for 

38 the combination alternative than for license renewal and the NGCC alternative. The cooling 

39 system for a new NGCC plant would have similar chemical discharges as STP, but the air 

40 emissions from the NGCC plant would emit particulates that would settle onto the river surface 

41 and introduce a new source of pollutants that would not exist if STP continued operating. 

42 However, the flow of the Colorado River would dissipate pollutants, which would minimize the 

43 exposure of fish and other aquatic organisms to pollutants.
Environmental Impacts of Alternatives

8-45

1 Construction and operation of offshore wind projects could affect aquatic communities. In its 

2 programmatic final EIS, MMS determined that construction and operations could have moderate 

3 impacts to aquatic organisms due to pile driving for installation of the structures, removal of 

4 structures by cutting or the use of explosives, and vessel traffic to and from the site 

5 (MMS 2007). Organisms most likely to be affected would be marine mammals, sea turtles, and 

6 fish due to noise from pile driving and vessel traffic as well as benthic organisms and habitats 

7 that are directly affected during site preparation. Siting offshore wind projects away from 

8 biologically productive areas could minimize such impacts. During operations, impacts from a 

9 spill as a consequence of a vessel collision could be moderate to major (MMS 2007).

10 Because little water use would be required as part of the Energy Efficiency and Conservation 

11 Program component of this alternative, impacts from the Energy Efficiency and Conservation 

12 Program on aquatic resources would likely be minimal.

13 Because of the potential habitat disturbances and noticeable impacts on aquatic organisms 

14 during construction and operation of offshore wind projects, impacts on aquatic resources from 

15 the combination alternative would be SMALL to MODERATE. Impacts from the NGCC portion 

16 of the alternative and Energy Efficiency and Conservation Program would not be noticeable 

17 because less water withdrawal and discharge would be required than for STP, Units 1 and 2. In 

18 addition, for the NGCC portion of the alternative, the construction activities would require BMPs, 

19 dredging would be short-term, and pollutants would dissipate without the Colorado River 

20 (minimizing exposure concentrations to aquatic resources).

21 8.4.5 Terrestrial Ecology

22 Constructing the NGCC plant would require approximately 92 ac (37 ha), which includes a new 

23 pipeline that would run approximately 2 mi (3 km) from the STP site to an existing pipeline. 

24 These estimates are based on GEIS scaling factors and details provided by STPNOC in its ER 

25 (STPNOC 2010a). Impacts on terrestrial ecology from onsite construction of the one NGCC unit 

26 would be less than the impacts described for the four-unit NGCC alternative, which are 

27 described in Section 8.2.

28 STPNOC estimated that a utility-scale wind plant requires 60 ac of land per MWe of installed 

29 capacity in open, flat terrain (STPNOC 2010a). Approximately 462,900 ac (187,300 ha) of land 

30 would be required for the installed capacity of 7,714 MWe. Of this area, approximately 2,186 ac 

31 (884 ha) would be temporarily disturbed during construction activities, and 937 ac (379 ha) 

32 would be permanently disturbed during operations. The permanently disturbed area would be 

33 filled with turbines, access roads, and other infrastructure, and the rest of the area would 

34 potentially be available for compatible other uses, such as agriculture (ranch, pasture, or 

35 cropland).

36 Impacts on terrestrial ecology from construction of the wind projects, including new transmission 

37 lines, could include loss of terrestrial habitat, an increase in habitat fragmentation, and 

38 corresponding increase in edge habitat, which may affect threatened and endangered species. 

39 Construction and operations of wind power projects could result in increased mortality of birds 

40 flying along the Trans-Gulf migratory route and might also cause increased mortality of 

41 migratory and resident bats. Offshore wind power development would also affect avian and 

42 aquatic resources. MMS (2007) determined that populations of marine and coastal birds as well 

43 as migrating inland birds may experience minor to potentially major impacts due to turbine 

44 collisions offshore and that endangered species would be the most impacted.

45 For this combination alternative, construction of the (a) 2-mi (3-km) natural gas pipeline and 

46 (b) transmission lines to connect the wind projects to distribution systems could result in habitat 

47 fragmentation and avian collisions with transmission lines. Depending on the length of new 
Environmental Impacts of Alternatives

8-46

1 transmission lines, impacts could potentially destabilize attributes of the terrestrial ecosystem 

2 because the transmission lines could permanently convert forested or cover habitats into open, 

3 maintained areas. To the extent possible, STPNOC would route the pipeline through previously 

4 disturbed areas (STPNOC 2010a). Threatened and endangered species may also be affected 

5 by construction of the natural gas pipeline and new transmission lines. Long-linear projects, 

6 such as pipelines and transmission lines, can often be sited to avoid sensitive areas.

7 Because no construction would occur for the Energy Efficiency and Conservation Program, 

8 impacts from the Energy Efficiency and Conservation Program on terrestrial resources would 

9 likely be minimal. Wind energy projects could have a noticeable impact on avian and bat 

10 communities because wind energy projects in the Trans-Gulf migratory route could result in 

11 increased mortality of migratory and resident birds and bats. Building new transmission lines 

12 would also increase habitat fragmentation. Offshore wind power could also result in increased 

13 mortality of coastal birds. Based on this information, impacts on terrestrial resources would be 

14 MODERATE.

15 8.4.6 Human Health

16 The human health risks from a combination of alternatives include the effects already discussed 

17 in Section 8.2.6 for the NGCC plant. However, the effects would be slightly less since one, 

18 rather than four, NGCC unit would be constructed and operated. For wind power, the GEIS 

19 notes that, except for a potential small number of occupational injuries, routine operations would 

20 not affect human health. For the Energy Efficiency and Conservation Program, the GEIS notes 

21 that the environmental impacts are likely to be centered on indoor air quality (NRC 1996). This 

22 is due to increased weatherization of the home in the form of extra insulation and reduced air 

23 turnover rates from the reduction in air leaks. However, the actual impact is highly site-specific 

24 and not yet well-established. Overall, human health risks to occupational workers and to 

25 members of the public from the combination alternative would likely be SMALL.

26 Noise during operations of NGCC plant would be limited to industrial processes and 

27 communications. Pipelines delivering natural gas fuel could be audible off site near compressor 

28 stations. Pipeline companies would need to adhere to local ordinances regarding maximum 

29 noise levels during construction and at compressor stations. Noise from the wind energy project 

30 would be audible in the immediate area but would likely be unobtrusive. Some noise impacts 

31 could occur in instances of energy conservation and efficiency upgrades to major building 

32 systems, but this impact would be intermittent and short-lived. Therefore, impacts from noise 

33 would likely be SMALL.

34 8.4.7 Land Use

35 The GEIS generically evaluates the impact of constructing and operating various replacement 

36 power plant alternatives on land use, both on and off each plant site. The analysis of land-use 

37 impacts focuses on the amount of land area that would be affected by the construction and 

38 operation of a single-unit NGCC plant at the STP site, wind energy projects, and energy 

39 conservation and efficiency.

40 Based on scaled GEIS estimates, constructing the single-unit NGCC unit would require 

41 approximately 92 ac (37 ha) at the STP site. This amount of land use would include other plant 

42 structures and associated infrastructure, such as the new 2-mi (3-km) pipeline, and is unlikely to 

43 exceed 92 ac (37 ha), excluding land for natural gas wells and collection stations.

44 In addition to onsite land requirements, land would be required off site for natural gas wells and 

45 collection stations. Scaling from GEIS estimates, approximately 2,400 ac (970 ha) would be 
Environmental Impacts of Alternatives

8-47

1 required for wells and collection stations to bring the natural gas to the power plant. Most of this 

2 land requirement would occur on land where natural gas extraction already occurs.

3 STPNOC estimated that utility-scale, land-based wind energy projects would require 60 ac of 

4 land per MWe of installed capacity in open, flat terrain (STPNOC 2010a). Approximately 

5 462,900 ac (187,300 ha) of land would be required for the installed capacity of 7,714 MWe. Of 

6 this area of land, approximately 2,186 ac (884 ha) would be temporarily disturbed during 

7 construction activities, and 937 ac (379 ha) would be permanently used for each wind turbine

8 during operations. Land used for the wind energy projects would be filled with turbines, access 

9 roads, and other infrastructure, and the rest of the land area between the turbines would be 

10 available for other uses, such as agriculture (ranch, pasture, or cropland).

11 Offshore wind energy projects would need to avoid impeding navigation. For both land-based 

12 and offshore wind projects, new electrical transmission systems would need to be built to 

13 connect the wind energy projects to the electric distribution system. 

14 The elimination of uranium fuel for STP could partially offset offsite land requirements for other 

15 energy projects. Scaling from GEIS estimates, approximately 2,560 ac (1,036 ha) would no 

16 longer be needed for the mining and processing of uranium. 

17 The land use impacts of the Energy Efficiency and Conservation Program would be minimal. 

18 The rapid replacement and disposal of older inefficient appliances and other equipment would 

19 generate waste material and could increase the size of landfills; however, given the time for 

20 program development and implementation, the cost of replacements, and the average life of 

21 equipment, the replacement process would probably be gradual. More efficient appliances and 

22 equipment would replace older equipment (especially in the case of frequently replaced items, 

23 such as light bulbs). In addition, many items (such as home appliances and industrial 

24 equipment) have recycling value and would not be disposed of in landfills.

25 The wind energy portion of this combination alternative would require a substantial amount of 

26 open land, although only a small portion would be used for wind turbines, access roads, and 

27 infrastructure. Therefore, land use impacts from the combination alternative could range from 

28 SMALL to MODERATE.

29 8.4.8 Socioeconomics

30 As previously discussed, socioeconomic impacts are defined in terms of changes to the 

31 demographic and economic characteristics and social conditions of a region. For example, the 

32 number of jobs created by the construction and operation of a new NGCC plant and wind power 

33 projects could affect regional employment, income, and expenditures. Two types of jobs would 

34 be created by this alternative: (1) construction jobs, which are transient, short in duration, and 

35 less likely to have a long-term socioeconomic impact; and (2) power plant and wind energy 

36 operation jobs, which have the greater potential for permanent, long-term socioeconomic 

37 impacts. Workforce requirements for the construction and operation of the combination 

38 alternative were evaluated to measure their possible effects on current socioeconomic 

39 conditions.

40 Based on GEIS estimates, the construction workforce would be up to 800 (maximum) workers 

41 for the NGCC plant. Scaling from STPNOC’s estimates, the estimated construction workforce 

42 would be up to 507 (maximum) workers (STPNOC 2010a). STPNOC’s estimate appears 

43 reasonable; therefore, it is used in this analysis. STPNOC did not provide a construction 

44 workforce estimate for wind energy projects. In Exelon Generation Company’s, LLC (Exelon)

45 ER for Limerick Generating Station, Exelon estimated a construction workforce of 200 for 

46 approximately half the amount of wind capacity needed for this combination alternative 
Environmental Impacts of Alternatives

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1 (Exelon 2011). This estimate includes both land-based and offshore wind energy projects. 

2 Scaling from this estimate, wind energy projects could require a construction workforce of up to 

3 400 workers. The relative economic impacts of this many workers on the local economy and tax 

4 base would vary, with the greatest impacts occurring in the communities where the majority of 

5 construction workers would reside and spend their income. As a result, local communities could 

6 experience a short-term economic “boom” from increased tax revenue and income generated by 

7 construction expenditures and the increased demand for temporary (rental) housing and 

8 business services. Some construction workers could relocate to Matagorda and surrounding 

9 counties in order to be closer to the construction work sites. However, given the proximity of 

10 STP to the Houston and other metropolitan areas, workers could commute to the various 

11 construction sites, thereby lessening the need for additional rental housing near STP. 

12 After completing the installation of the single NGCC unit and wind turbines, local communities 

13 could experience a return to pre-construction economic conditions. Based on this information, 

14 and the given number of workers, socioeconomic impacts during construction in communities 

15 near the STP site and wind farms could be SMALL, due to the small number of workers needed 

16 to construct the NGCC plant and because the wind energy project workers would be spread 

17 throughout the service region.

18 Scaled from GEIS estimates, the single-unit NGCC power plant operation workforce would be 

19 100 workers. Based on STPNOC’s estimates, the maximum NGCC operation workforce would 

20 be 23 workers (STPNOC 2010a). STPNOC’s estimate appears reasonable; therefore, it is used 

21 in this analysis. STPNOC did not provide an operations workforce estimate for wind energy 

22 projects. In Exelon’s ER for the Limerick Generating Station, Exelon estimated a wind energy

23 workforce of 50 workers for approximately half the amount of wind capacity needed for this 

24 combination alternative (Exelon 2011). This estimate includes both land-based and offshore 

25 wind energy projects. Scaling from this estimate, wind energy projects could require an 

26 operations workforce of up to 100 workers. The amount of property taxes paid under the 

27 combination alternative may increase if additional land is required off site to support this 

28 alternative. As noted in the GEIS, an Energy Conservation and Efficiency Program would also 

29 create jobs for additional workers (NRC 1996). Socioeconomic impacts during operations could 

30 range from SMALL to MODERATE as the STP site transitions to the new, single-unit NGCC 

31 power plant. The reduction in overall employment at STP could affect property tax revenue and 

32 income in local communities and businesses. In addition, the permanent housing market could 

33 also experience increased vacancies and decreased prices if operations workers and their 

34 families move out of the region.

35 8.4.9 Transportation

36 Construction and operation of an NGCC plant at the STP site and wind energy projects 

37 throughout the region would increase the number of vehicles on the roads near these facilities. 

38 During construction, cars and trucks would deliver workers, materials, and equipment to the 

39 worksites. Traffic volumes on local roads near these worksites would noticeably increase and 

40 peak during shift changes resulting in temporary levels of service impacts and delays at 

41 intersections. Transporting components of wind turbines via roadways could also have a 

42 noticeable impact on traffic conditions, and this effect is likely to be spread over a large area. 

43 Pipeline construction and modification to existing natural gas pipeline systems could also have a 

44 temporary impact. Based on this information, traffic-related transportation impacts during 

45 construction could range from SMALL to MODERATE depending on the location of the wind 

46 energy sites, road capacities, and traffic volumes.

47 Traffic volumes on local roads near construction sites after the installation of the NGCC and 

48 wind turbines would be noticeably reduced. Given the small number of workers needed to 
Environmental Impacts of Alternatives

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1 operate the energy projects in this combination alternative, the levels of service impacts on local 

2 roads during shift changes would be SMALL. In addition, wind energy project operation workers 

3 would be spread across the service region, and any traffic-related transportation effects from the 

4 energy efficiency alternative would also be widely distributed. Therefore, overall transportation 

5 impacts for this combination alternative during operations would be SMALL.

6 8.4.10 Aesthetics

7 The analysis of aesthetic impacts focuses on the degree of contrast between the surrounding 

8 landscape and the visibility of the NGCC plant and wind energy projects. In general, aesthetic 

9 changes would be limited to the immediate vicinity of the STP site and wind energy projects. 

10 Aesthetic impacts from the NGCC plant component of the combination alternative would be 

11 essentially the same as those described for the NGCC alternative in Section 8.2.10, except 

12 there would be one unit rather than four units. During construction, all of the clearing and 

13 excavation would occur on the STP site. These activities may be visible from offsite roads, 

14 particularly FM 521. Since the STP site already appears industrial, construction of the NGCC 

15 power plant would appear similar to onsite activities during refueling outages. Power plant 

16 infrastructure would be smaller and less noticeable than STP containment and turbine buildings. 

17 Noise during plant operations would be limited to industrial processes and communications. 

18 Pipelines delivering natural gas fuel could be audible off site near gas compressor stations. In 

19 general, aesthetic changes due to the construction and operation of the single-unit NGCC would 

20 be limited to the immediate vicinity of the STP site and would be SMALL.

21 The wind energy projects would have the greatest visual impact. Approximately 3,877 wind 

22 turbines at over 300 ft (100 m) tall would be spread across multiple land-based sites covering 

23 462,900 ac (187,300 ha). The turbines would dominate the view and would likely become the 

24 major focus of attention. Offshore wind projects would also be visible because of the height and 

25 size of the wind turbine generators (MMS 2007). Depending on their location, the aesthetic 

26 impacts from the construction and operation of the wind energy projects would be MODERATE 

27 to LARGE.

28 Impacts from the Energy Conservation and Efficiency Program would be SMALL because it 

29 would not require any visible changes to existing infrastructure. 

30 8.4.11 Historic and Archaeological Resources

31 The same considerations, discussed in Section 8.2.11, for the impact of the construction of a 

32 four-unit NGCC plant on historic and archaeological resources apply to the construction 

33 activities that would occur on the STP site for a new one-unit NGCC plant. As described in 

34 Section 2.2.10, much of the STP site has been previously disturbed by the construction of STP, 

35 Units 1 and 2. In addition, in preparation for the COL application for Units 3 and 4, STPNOC 

36 conducted a cultural resources assessment of the STP site. STPNOC reviewed existing 

37 information for the STP site and the area within a 10-mi (16-km) radius. STPNOC concluded 

38 that any cultural resource sites that may have existed on site would no longer retain their 

39 integrity because the area was heavily disturbed during the construction of Units 1 and 2 

40 (STPNOC 2010b). In December 2006, STPNOC reported these findings to the SHPO at the 

41 Texas Historical Commission. The SHPO concurred, in January 2007, that there would be no 

42 impacts to historic properties (STPNOC 2006; THC 2007).

43 There is a low potential for cultural resources to be located in previously undisturbed portions of 

44 the STP site. However, if the NGCC unit was to be sited within undisturbed areas or within 

45 areas of known cultural sensitivity (historic grave site located on the property and described in 
Environmental Impacts of Alternatives

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1 Section 2.2.10), these areas would need to be surveyed by a professional archaeologist to 

2 identify and develop possible mitigation measures to address any adverse effects from project 

3 activities. NRC assumes the plant operator would follow similar procedures to those described 

4 in the final EIS for STP, Units 3 and 4 (NRC 2011), should the plant operator discover any 

5 historic or cultural resources during ground-disturbing activities associated with building the new 

units. 6 

7 Studies would be needed for all areas of potential disturbance at the proposed plant site, wind 

8 project locations, and along associated corridors where new construction would occur (e.g., the 

9 new 2-mi pipeline, roads, transmission corridors, rail lines, or other ROWs). Any affected areas 

10 would need to be surveyed to identify and record historic and archaeological resources, identify 

11 cultural resources (e.g., traditional cultural properties), and develop possible mitigation 

12 measures to address any adverse effects from ground-disturbing activities. In most cases, 

13 long-linear projects (e.g., pipelines) can be sited to avoid areas of greatest sensitivity.

14 Construction of wind energy projects could affect cultural resource because areas 

15 approximately 15 to 25 ft (4.6 to 6 m) in diameter would be excavated. Wind turbines can likely 

16 be sited to avoid sensitive areas because the disturbed area is a small portion of the total 

17 amount of area required. In addition, wind turbines within the viewshed of traditional cultural 

18 properties and historic properties could have noticeable impacts to cultural and historic 

19 resources. Proper siting may be able to mitigate these potential impacts.

20 The NRC staff determined that the impact on historic and archaeological resources from the 

21 NGCC portion of the combination alternative would be SMALL for the following reasons:

22 • NRC (2011) and STPNOC (2010a, 2010b) did not identify any cultural 

23 resources that could be affected by Units 3 and 4. 

24 • The SHPO determined that construction for Units 3 and 4 would not affect 

25 cultural and historic resources. 

26 • Long-linear projects (e.g., pipelines) can usually be sited to avoid sensitive 

27 areas. 

28 • NRC assumes that the plant operator would follow environmental compliance 

29 procedures for new ground-disturbing activities.

30 Depending on the resource richness of the site chosen for the wind energy projects, the impacts 

31 could range between SMALL to MODERATE. Impacts to historic and archaeological resources 

32 from implementing the Energy Efficiency and Conservation Program would be SMALL and 

33 would unlikely affect land use or historical or cultural resources elsewhere in Texas. Therefore, 

34 the overall impacts on historic and archaeological resources from the combination alternative 

35 could range from SMALL to MODERATE.

36 8.4.12 Environmental Justice 

37 The environmental justice impact analysis evaluates the potential for disproportionately high and 

38 adverse human health and environmental effects on minority and low-income populations that 

39 could result from the construction and operation of a new NGCC power plant at the STP site, 

40 wind energy projects, and the Energy Efficiency and Conservation Program. As previously 

41 discussed in Section 8.1.12, such effects may include human health, biological, cultural, 

42 economic, or social impacts. Some of these potential effects have been identified in resource 

43 areas discussed in this SEIS. For example, increased demand for rental housing during plant 

44 construction could disproportionately affect low-income populations. Minority and low-income 

45 populations are subsets of the general public living near the STP site and wind energy project 
Environmental Impacts of Alternatives

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1 sites, and all are exposed to the same hazards generated from constructing and operating an 

2 NGCC plant and wind energy projects. Section 4.9.7, “Environmental Justice,” presents 

3 demographic information about minority and low-income populations residing in the vicinity of 

4 the STP site. 

5 Potential impacts to minority and low-income populations from the construction and operation of 

6 a new NGCC plant at the STP site and wind energy projects would mostly consist of 

7 environmental and socioeconomic effects (e.g., noise, dust, traffic, employment, and housing 

8 impacts). Noise and dust impacts during construction would be short-term and primarily limited 

9 to onsite activities. Minority and low-income populations residing along site access roads would 

10 be directly affected by increased commuter vehicle and truck traffic. However, because of the 

11 temporary nature of construction, these effects would only occur during certain hours of the day 

12 and are unlikely to be high and adverse. Increased demand for rental housing during 

13 construction of the NGCC and wind energy projects could also affect low-income populations 

14 living near STP and wind energy project sites. Given the proximity of STP to the Houston 

15 metropolitan area, many construction workers could commute to the STP and wind energy 

16 project sites, thereby lessening the additional need for rental housing near STP. 

17 Low-income populations could benefit from weatherization and insulation in an Energy 

18 Conservation and Efficiency Program. This could have a greater beneficial effect on 

19 low-income populations than the general population because low-income households generally 

20 experience greater home energy burdens than the average household. 

21 Based on this information, and the analysis of human health and environmental impacts 

22 presented in this SEIS, the combination alternative would not create disproportionately high and 

23 adverse human health and environmental effects on minority and low-income populations.

24 8.4.13 Waste Management

25 During the construction stage for the NGCC plant and wind projects, land clearing and other 

26 construction activities would generate wastes that could be recycled, disposed of on site, or 

27 shipped to the offsite waste disposal facility. During the operational stage, spent SCR catalysts, 

28 which control nitrogen oxide emissions from the NGCC plant, would make up the majority of the 

29 waste generated by this alternative.

30 There would be an increase in wastes generated during installation or implementation of energy 

31 conservation measures, such as appropriate disposal of old appliances, installation of control 

32 devices, and modifications of buildings. New and existing recycling programs would help to 

33 minimize the amount of generated waste.

34 The NRC concludes that overall waste impacts from the combination alternative would be 

35 SMALL.

36 8.4.14 Summary of Impacts of the Combination Alternative

37 Table 8–5 summarizes the environmental impacts of the combination alternative compared to 

38 continued operation of the STP.

39
Environmental Impacts of Alternatives

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1 Table 8–5. Summary of Environmental Impacts of the Combination Alternative

2 Compared to Continued Operation of STP, Units 1 and 2

Category Combination Alternative Continued STP Operation

Air quality SMALL to MODERATE SMALL

Surface water SMALL SMALL

Groundwater SMALL SMALL

Aquatic resources SMALL to MODERATE SMALL

Terrestrial resources MODERATE SMALL

Human health SMALL SMALL to MODERATE

Land use SMALL to MODERATE SMALL

Socioeconomics SMALL to MODERATE SMALL

Transportation SMALL to MODERATE SMALL

Aesthetics SMALL to LARGE SMALL

Historic & archaeological SMALL to MODERATE SMALL

Waste management SMALL SMALL

8.5

4 Under the purchased power alternative, STPNOC would purchase 2,500 MWe of electricity from 

5 other power generators. No new generating capacity would be built and operated by STPNOC. 

6 In its ER, STPNOC assumed that purchased power is a reasonable alternative for the following 

7 reasons:

3 Purchased Power

8 • A wholesale electricity market currently exists in the ERCOT region. 

9 • ERCOT implements rules to anticipate and meet electricity demands and 

10 promote competition among electricity suppliers. 

11 • Most of ERCOT’s retail customers can choose a supplier to purchase 

12 electricity.

13 If STPNOC purchased electricity, the source of all generated electricity would be within the 

14 ERCOT region because ERCOT operates wholly within the State of Texas and does not 

15 interconnect with neighboring reliability regions for the purpose of importing or exporting power 

16 (STPNOC 2010a). In 2010, electricity produced within the ERCOT region was dominated by 

17 coal (40 percent), followed by natural gas (38 percent), nuclear (13 percent), wind (8 percent), 

18 and other sources (1 percent) (ERCOT 2011a). As of April 2011, new energy projects under 

19 ERCOT’s review included 36,124 MWe of wind power (58 percent); 12,954 MWe of natural 

20 gas-fired generation (21 percent); 5,900 MWe of nuclear power (9 percent); 4,075 MWe of 

21 coal-fired generation (7 percent); 1,454 MWe solar power (2 percent); 150 MWe of 

22 biomass-fired generation (less than 1 percent); and 1,980 MWe of other resources (3 percent) 

23 (ERCOT 2011a). Based on current and likely future electric generation, NRC assumed that the 

24 purchased power would likely come from a mixture of coal, natural gas, wind, and nuclear 

25 energy.

26 Because the purchased power would be limited to resources available within the ERCOT 

27 region, new energy generation facilities may need to be built to supply the electricity. 
Environmental Impacts of Alternatives

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1 Construction impacts would be similar to those described under the new nuclear, coal, natural 

2 gas, and wind alternatives described in the previous sections. In addition to the construction 

3 impacts described in Sections 8.1 through 8.3, there could be additional impacts if new plants 

4 are built on greenfield sites. For example, impacts to aquatic and terrestrial resources and 

5 historical and cultural resources are likely to be greater due to land clearing of previously 

6 undisturbed areas. Additional impacts would also occur from construction of support 

7 infrastructure, like transmission lines and roads. Furthermore, the community would not be 

8 familiar with the appearance of a power facility, which would change the region’s aesthetic 

9 character. Workers skilled in power plant or wind farm operations may not be available near a 

10 greenfield site.

11 During operations, impacts from new nuclear, coal-fired, and natural gas-fired plants and wind 

12 energy projects would be similar to that described under the new nuclear, coal, natural gas, and 

13 wind alternatives described in the previous sections. Impacts from the operations of existing 

14 coal- and natural gas-fired plants would likely be greater than the operations of new plants 

15 because older plants are more likely to be less efficient and without modern emissions controls. 

16 Air quality impacts from the combination of all sources would likely be greater than license 

17 renewal because a large portion of the purchased power would likely be from coal- and natural

18 gas-fired plants.

19 While purchased power is a reasonable alternative, the potential impacts of constructing and 

20 operating new power generating facilities is addressed elsewhere in this chapter. In general, 

21 the impacts would likely be greater than license renewal due to potential new construction and 

22 because continued operation of older plants could result in higher emissions. Ultimately, the 

23 impacts would depend on the mix of sources used to supply the 2,500 MWe of electricity. 

24 Below is a brief summary of the impacts for each resource area. 

25 8.5.1 Air Quality

26 New and existing nuclear plants and wind farms would not have noticeable impacts on air 

27 quality. New and existing natural gas- and coal-fired plants would have noticeable impacts on 

28 air quality; both natural gas- and coal-fired plants emit higher amounts of nitrogen oxides, sulfur 

29 oxides, PM, HAPs, carbon monoxide, carbon dioxide, and mercury as compared to STP, Units 1 

30 and 2. The impacts on air quality would be SMALL to MODERATE.

31 8.5.2 Surface Water and Groundwater Resources

32 New and existing nuclear, coal-fired, and natural gas-fired plants and wind energy projects 

33 would not have noticeable impacts on water resources assuming all energy generating facilities 

34 operate within their associated water quality and water use permits. The impacts on surface 

35 water and groundwater resources would be SMALL.

36 8.5.3 Terrestrial and Aquatic Ecology

37 New and existing natural gas-fired and nuclear plants would not have noticeable impacts on 

38 aquatic and terrestrial resources assuming plants are built in areas that avoid sensitive species 

39 and habitats. New, land-based wind energy projects would not have noticeable impacts on 

40 aquatic resources assuming projects are built in areas that avoid sensitive species and habitats. 

41 New wind energy projects would have noticeable impacts on avian and bat communities and 

42 new offshore wind energy projects could have noticeable impacts on fish, whales, turtles, 

43 benthic organisms, and other marine life. New and existing coal-fired plants would have 

44 noticeable impacts on terrestrial communities primarily due to the deposition of ash and other 
Environmental Impacts of Alternatives

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1 pollutants and because of the extent of terrestrial habitat disturbance associated with coal 

2 mining. The impacts on terrestrial and aquatic ecology would be SMALL to MODERATE. 

3 8.5.4 Human Health

4 New and existing nuclear, coal-fired, and natural gas-fired plants and wind energy projects 

5 would have SMALL impacts on human health due to the extent of regulations to protect public 

6 health. 

7 8.5.5 Land Use

8 Purchased power from existing power plants would not cause any land use changes. New 

9 power plants would likely be constructed at existing power plant sites. Purchased power from 

10 coal- and natural gas-fired plants could have a noticeable impact on land use due to the amount 

11 of land required for coal mining and gas drilling. New wind energy projects would have a 

12 noticeable land use impact because of the large amount of land required for wind farms. Land 

13 use impacts would be SMALL to MODERATE.

14 8.5.6 Socioeconomics (including transportation and aesthetics)

15 Purchased power from existing power plants would not have any socioeconomic impact 

16 because there would be no change in power plant operations or workforce. Construction of new 

17 electrical power generating facilities could cause noticeable short-term socioeconomic and 

18 transportation impacts due to the number of construction workers required to build the new 

19 power plant. Traffic volumes would increase on local roads during shift changes. 

20 Wind energy projects would have the greatest visual impact; wind turbines would dominate the 

21 view and would likely become the major focus of attention.

22 The impacts would be SMALL to LARGE.

23 8.5.7 Historic and Archaeological Resources

24 Purchased power from existing power plants would not have any impact on historic and 

25 archaeological resources. In addition, ground-disturbing maintenance activities during 

26 operations also have the potential to affect historic and archaeological resources.

27 Construction of new nuclear, coal-fired, and natural gas-fired plants and wind energy projects 

28 could affect archaeological and historic resources. Archaeological surveys would need to be 

29 conducted prior to any excavations at proposed power plant sites. After surveys are completed, 

30 sensitive resource areas could be avoided or mitigated prior to construction. The overall 

31 impacts on historic and archaeological resources would be SMALL to MODERATE. 

32 8.5.8 Environmental Justice

33 Low-income populations could be disproportionately affected by increased utility bills due to the 

34 cost of purchased power. However, programs are available to assist low-income families in 

35 paying for increased electrical costs.

36 Potential impacts to minority and low-income populations from the construction and operation of 

37 new power plants would mostly consist of environmental and socioeconomic effects (e.g., noise, 

38 dust, traffic, employment, and housing impacts). Noise and dust impacts during construction 

39 would be short-term and primarily limited to onsite activities. Minority and low-income 

40 populations residing along site access roads would be directly affected by increased commuter 
Environmental Impacts of Alternatives

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1 vehicle and truck traffic. However, because of the temporary nature of construction, these 

2 effects would only occur during certain hours of the day and are unlikely to be high and adverse. 

3 Increased demand for rental housing during construction could also affect low-income 

4 populations living near the construction site. However, workers could commute to the 

5 construction site, thereby lessening the need for additional rental housing near the construction 

6 sites. Based on this information, and the analysis of human health and environmental impacts 

7 presented in this section, the purchased power alternative could disproportionately affect 

8 low-income populations, but these effects would not be high and adverse.

9 8.5.9 Waste Management

10 New and existing nuclear and natural gas-fired plants and wind energy projects would not have 

11 noticeable impacts. However, new and continued generation of coal-fired plants would have 

12 noticeable impacts due to the accumulation of ash and scrubber sludge. The overall impacts on 

13 waste management would range from SMALL to MODERATE.

14 8.5.10 Summary of Impacts of the Purchased Power Alternative

15 Table 8–6 summarizes the environmental impacts of the purchased power alternative compared 

16 to continued operation of the STP.

17 Table 8–6. Summary of Environmental Impacts of the Purchased Power Alternative

18 Compared to Continued Operation of STP, Units 1 and 2

Category Purchased Power Continued STP Operation

Air quality SMALL to MODERATE SMALL

Surface water & groundwater SMALL SMALL

Aquatic & terrestrial resources SMALL to MODERATE SMALL

Human health SMALL SMALL to MODERATE

Land use SMALL to MODERATE SMALL

Socioeconomics (including 

transportation & aesthetics)

SMALL to LARGE SMALL

Historic & archaeological SMALL to MODERATE SMALL

Waste management SMALL to MODERATE SMALL

8.6

20 Alternatives to license renewal that were considered and eliminated from detailed study are 

21 presented in this section. These alternatives were eliminated due to technical, resource 

22 availability, or current commercial limitations. Many of these limitations would continue to exist 

23 when the current STP licenses expire. NRC evaluated an alternative of wind energy in 

24 combination with an NGCC plant and energy efficiency and conservation programs in 

25 Section 8.4. The evaluations of wind technology and energy conservation and efficiency 

26 appearing in this section are as discrete alternatives.

19 Alternatives Considered but Dismissed
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1 8.6.1 Offsite Nuclear-, Gas-, and Coal-Fired Capacity

2 While nuclear-, gas-, and coal-fired power generating alternatives like those considered in 

3 Sections 8.1 through 8.3, respectively, could be constructed offsite, the impacts would be 

4 greater than constructing these facilities and making use of existing infrastructure at the STP 

5 site. Additional impacts would occur from the construction of new water intake and discharge

6 structures, as well as other support infrastructure, including transmission lines and roads that 

7 are already present on the STP site. Furthermore, the community around STP is already 

8 familiar with the appearance of a power generating facility, and it is an established part of the 

9 region’s character. Workers skilled in power plant operations may not be available in other 

10 locations. However, support infrastructure and skilled power-plant workers may be available 

11 near existing industrial sites, but remediation may also be necessary in order to make the site 

12 ready for redevelopment. In short, an existing power plant site would present the best location 

13 for a new replacement power facility.

14 8.6.2 Energy Conservation and Energy Efficiency

15 Though often used interchangeably, energy conservation and energy efficiency are different 

16 concepts. Energy efficiency means deriving a similar level of services by using less energy 

17 while energy conservation indicates a reduction in energy consumption. Both fall into a larger 

18 category known as demand-side management. Demand-side management measures address 

19 energy end uses—unlike energy supply alternatives discussed in previous sections. 

20 Demand-side management can include measures that do the following: 

21 • shift energy consumption to different times of the day to reduce peak loads, 

22 • interrupt certain large customers during periods of high demand, 

23 • interrupt certain appliances during high demand periods, 

24 • replace older, less efficient appliances, lighting, or control systems, and 

25 • encourage customers to switch from gas to electricity for water heating and 

26 other similar measures that utilities use to boost sales.

27 Unlike other alternatives to license renewal, the GEIS notes that conservation is not a discrete 

28 power-generating source; nonetheless, it represents an option that states and utilities may use 

29 to reduce their need for power generation capability, so the NRC addressed it in the GEIS 

30 (NRC 1996).

31 In 2010, the Public Utility Commission of Texas approved Substantive Rule § 25.181, which 

32 requires all electric transmission and distribution utilities within the ERCOT market, including 

33 CPS Energy and Austin Energy (two of the owners of STP, Units 1 and 2), to use demand-side 

34 management to reduce their customers’ energy consumption by a minimum of 20 percent of the 

35 utility’s annual growth. The rule further requires a minimum of 25 percent reduction in 2012 and 

36 30 percent in 2013 and beyond.

37 CPS Energy and Austin Energy implement programs to promote demand-side management. 

38 These programs include load curtailment incentives during periods of peak demand; rebates 

39 and financial incentives for commercial, industrial, and residential customers for installation of 

40 energy-efficient appliances and equipment; and the adoption of updated energy codes for new 

41 building construction (STPNOC 2010a). Demand-side management programs from other Texas 

42 utilities would also help offset the 2,500 MWe produced by STP because STPNOC sells power 

43 produced at STPNOC into the ERCOT interconnection (STPNOC 2010a).
Environmental Impacts of Alternatives

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1 Because Substantive Rule § 25.181 already requires annual 30 percent reductions in energy 

2 consumption from demand-side management, it is unlikely that additional increases in energy 

3 efficiency in the State of Texas will have grown enough to offset the loss of 2,500 MWe

4 produced by STP by the time the licenses expire in 2027 and 2028. Because of this, the NRC 

5 staff has not evaluated energy conservation and efficiency as a discrete alternative to license 

6 renewal. NRC evaluated an alternative with energy efficiency and conservation programs in 

7 combination with an NGCC plant and wind energy in Section 8.4.

8 8.6.3 Wind Power

9 Texas has significant wind energy resources and leads the Nation in wind-powered generation

10 capacity (DOE 2011b). As discussed in Section 8.4, as of June 30, 2011, the installed wind 

11 capacity in Texas was 10,135 MWe (DOE 2011b). Wind resource areas in the Texas 

12 Panhandle, along the Gulf coasts south of Galveston and in the mountain passes and ridgetops 

13 of the Trans-Pecos region, offer some of the greatest wind power potential in the U.S. The 

14 Roscoe Wind Farm in Texas is the largest wind farm in the world with a total capacity of 

15 781.5 MWe spread across approximately 100,000 ac (40,470 ha) in four counties near Roscoe 

16 in central Texas.

17 Newer wind turbines typically operate at approximately a 36 percent annual capacity factor

18 (DOE 2008). Wind turbines generally can serve as an intermittent power supply (NPCC 2005). 

19 Wind power might serve as a means of providing baseload power (a) if it is combined with 

20 energy storage mechanisms, such as pumped hydroelectric or compressed air energy storage 

21 (CAES), (b) if many wind farms are interconnected to one another on the transmission grid, as 

22 described in Section 8.4, or (c) if another readily dispatchable power source is used when wind 

23 power is unavailable (e.g., hydropower). 

24 EIA is not projecting any growth in pumped storage capacity through 2035 (EIA 2011a). As 

25 described below, the potential for new hydroelectric development in Texas is limited. Therefore, 

26 NRC concludes that the use of pumped storage in combination with wind turbines to generate 

27 2,500 MWe is unlikely in the ERCOT region or Texas.

28 A CAES plant is another potential storage mechanism that could potentially serve as means for 

29 wind to provide baseload power. A CAES plant consists of motor-driven air compressors that 

30 use low cost off peak electricity to compress air into an underground storage medium. During 

31 high electricity demand periods, the stored energy is recovered by releasing the compressed air 

32 through a combustion turbine to generate electricity (NPCC 2009). Only two CAES plants are 

33 currently in operation. A 290-MWe plant near Bremen, Germany, began operating in 1978, and 

34 a 110-MWe plant located in McIntosh, Alabama, has been operating since 1991. Both facilities 

35 use salt caverns (Succar and Williams 2008). A CAES plant requires suitable geology, such as 

36 an underground cavern for energy storage, which would likely be available in Texas due to the 

37 presence of salt domes. A 268-MWe CAES plant coupled to a wind farm, the Iowa Stored 

38 Energy Park, had been proposed for construction near Des Moines, Iowa. The facility would 

39 have used a porous rock storage reservoir for the compressed air (Succar and Williams 2008). 

40 However, the project has been cancelled due to geologic concerns (ISEPA 2011). Other pilot, 

41 demonstration, prototype, and research projects involving CAES have been announced, 

42 including projects in Texas and throughout the U.S. Norton Energy Storage is proposing to 

43 construct a CAES plant that would provide up to 2,700 MWe of storage capacity in Norton, Ohio 

44 (OPSB 2011). Projects such as the Conoco-Phillips and General Compression venture may 

45 use compressed air storage directly without the combustion of fuel such as natural gas. 

46 However, NRC is not aware of a CAES project coupled with wind generation that is providing 

47 baseload power. Therefore, NRC concludes that the use of CAES in combination with wind 

48 turbines to generate 2,500 MWe in the ERCOT region is unlikely.
Environmental Impacts of Alternatives

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1 A significant challenge for new wind power facilities is that wind farms can be built more quickly 

2 than transmission lines. It can take a year to build a wind farm, but 5 years to build the 

3 transmission lines needed to send power to cities. Moreover, wind power developers are 

4 reluctant to build where transmission lines do not yet exist, and utilities are equally reluctant to 

5 install transmission in areas that do not yet have power generators (TSECO 2008). Archer and 

6 Jacobson (2007) examined whether wind projects interconnected to one another on the 

7 transmission grid could provide a source of baseload power, as described in Section 8.4. This 

8 study determined that interconnecting wind farms through the transmission grid increases the 

9 probability that at least one site experiences sufficient wind to produce electricity. Thus, as 

10 more sites are added to the transmission grid, the interconnected wind farms provide electricity 

11 that is comparable to a single wind farm providing near constant deliverable wind power. 

12 However, due to the amount of new transmission lines required and the cost limitations of 

13 building new transmission lines, it is unlikely that sufficient transmission lines could be built to 

14 interconnect sufficient wind projects to provide 2,500 MWe of baseload power (with an installed 

15 capacity of at least 12,000 MWe).

Offshore Wind

27 The National Renewable Energy Laboratory (NREL) issued a report that identified offshore wind 

28 projects in the southeast (NREL 2010). The report identified the proposed Coastal Point Energy 

29 Project (also called the Galveston Wind Project) off the Texas coast near Galveston 

30 (approximately 9 mi from shore), which is anticipated to have a capacity of 300 MWe

31 (NREL 2010). No other wind energy projects were identified by NREL off the coast of Texas or 

32 its adjoining State (Louisiana).

16 . Wind data suggest there is potential for offshore wind farms along the coast of 

17 Texas, although project costs likely limit the future potential of large-scale projects (NRC 2011; 

18 Southern and GIT 2007). Southern Company and the Georgia Institute of Technology (GIT) 

19 studied the viability of offshore wind turbines in the southeast and determined that offshore 

20 project costs would run approximately 50 to 100 percent higher than land-based systems. Also, 

21 based on current prices for wind turbines, the 20-year levelized cost of electricity produced from 

22 an offshore wind farm would be above the current production costs from existing power 

23 generation facilities. In addition, the current commercially available offshore wind turbines are 

24 not built to withstand major hurricanes above a Category 3 or a 1-minute sustained wind speed 

25 of 124 mph. Additional details on the limitations of offshore wind power as a source of baseload 

26 power is described in the final EIS for STP, Units 3 and 4 (NRC 2011).

Conclusion

38 8.6.4 Solar Power

33 . Although wind power is an important energy resource in the ERCOT region and 

34 Texas, NRC concludes that a wind energy facility at or in the vicinity of the STP site or 

35 elsewhere in the ERCOT region would not currently be a reasonable alternative to license 

36 renewal. NRC evaluated an alternative of wind energy in combination with an NGCC plant and 

37 energy efficiency and conservation programs in Section 8.4.

39 Solar technologies use the sun’s energy to produce electricity at a utility scale. Solar energy 

40 can be converted to electricity using solar thermal technologies or photovoltaics. Solar thermal 

41 technologies employ concentrating devices to create temperatures suitable for power 

42 production. Concentrating thermal technologies are currently less costly than photovoltaics for 

43 bulk power production.

The ERCOT region receives 3.5 to 7.0 kWh/m2 44 /day of direct solar radiation (STPNOC 2010a). 

45 Solar power constituted less than 1 percent of electricity produced in the ERCOT region during 

46 2010 (ERCOT 2011a). As of April 2011, applications for energy projects under review at 

47 ERCOT included 1,454 MWe of proposed solar projects (ERCOT 2011a).
Environmental Impacts of Alternatives

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1 As described in the GEIS, solar power is intermittent (i.e., it does not work at night and cannot 

2 serve baseload when the sun is not shining), and the efficiency of collectors varies greatly with 

3 weather conditions. Therefore, solar power by itself would not be able to provide baseload 

4 power as an alternative to Units 1 and 2. Rather, a solar-powered alternative would require 

5 energy storage or backup power supply from other sources to potentially supply baseload power 

6 during periods when the sun is not shining. Potential storage mechanisms include pumped 

7 storage, CAES, molten salt storage, or thermal storage. As described above in Section 8.6.3 

8 and in STP, Units 3 and 4, EIS (NRC 2011), storage possibilities in this region of Texas are 

9 limited. NRC is not aware of any storage facility coupled with solar generation that is providing 

10 baseload power.

11 For the term of license renewal, because solar energy is an intermittent resource, and the 

12 amount of solar capacity required to replace Units 1 and 2 far exceeds existing and planned 

13 amounts of future solar power generation within ERCOT and exceeds storage potential (if 

14 CAES or pumped storage were used), NRC does not consider solar energy to be a reasonable 

15 alternative to license renewal.

16 8.6.5 Hydroelectric Power

17 Hydropower constituted less than 1 percent of electricity produced in the ERCOT region during 

18 2010 (ERCOT 2011a). EIA’s reference case in its Update Annual Energy Outlook 2011 projects 

19 that U.S. electricity production from hydropower plants will remain essentially stable through 

20 2035 (EIA 2011a). Idaho National Energy and Environmental Laboratory (1998) estimated that 

21 1,234 MWe of undeveloped potential hydroelectric resources at 89 sites occur throughout the 

22 State of Texas. Given that the available hydroelectric potential in the State of Texas constitutes 

23 less than one-tenth of the generating capacity of STP, the NRC staff did not evaluate 

24 hydropower as a reasonable alternative to license renewal.

25 8.6.6 Wave and Ocean Energy

26 Wave and ocean energy has created considerable interest in recent years. Ocean waves, 

27 currents, and tides are often predictable and reliable. Ocean currents flow consistently, while 

28 tides can be predicted months and years in advance with well-known behavior in most coastal 

29 areas. Most of these technologies are in relatively early stages of development. The potential 

30 for wave and ocean energy in Texas is limited because the Gulf of Mexico is shallow and 

31 semi-enclosed (TCPA 2008). Because most technologies are relatively undeveloped (and none 

32 are developed on the scale of STP), and because the Gulf of Mexico has limited potential for 

33 wave and ocean energy, the NRC did not consider wave and ocean energy as a reasonable 

34 alternative to STP license renewal.

35 8.6.7 Geothermal Power

36 Hydrothermal resources, reservoirs of steam or hot water that can be used for electrical 

37 generation, are available primarily in the western states, including Hawaii, Alaska, California, 

38 Utah, and Nevada (TCPA 2008). This type of geothermal energy has an average capacity 

39 factor of 90 percent and can be used for baseload power where available. Geothermal systems 

40 have a relatively small footprint and minimal emissions (MIT 2006). However, Texas does not 

41 have the sort of readily accessible, high-temperature hydrothermal resource (Virtus 2008).

42 Lower-temperature geothermal resources (90 °F to 160 °F) occur in the central part of Texas 

43 and along the Rio Grande. In the technical report (TCPA 2008), Texas Comptroller of Public 

44 Accounts (TCPA) suggests that such areas could provide low-temperature applications, such as 

45 space heating. Other uses could also include greenhouse cultivation, aquaculture, crop drying, 
Environmental Impacts of Alternatives

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1 and milk pasteurization. The potential for hot dry rock geothermal power in Texas is presently 

2 unknown (Virtus 2008).

3 Geopressured-geothermal power plants use existing, deep oil and gas wells to access hot fluids 

4 that have been co-produced from oil and gas exploration, such as geopressured reservoirs of 

5 hot water and natural gas or hot wastewater from deep oil and gas wells. This technology has 

6 future potential in Texas because hydrocarbon exploration and production industries have data 

7 on the thermal characteristics in existing wells and because areas with sufficient geothermal 

8 energy may exist where deep oil and gas wells exists (TCPA 2008). Current data suggest that 

9 wells 16,000 ft (4,877 m) or deeper in the ERCOT region contain high-temperature fluid (250 °F 

10 (121 °C) or greater), and some wells are above 400 °F (204 °C) (STPNOC 2010a). In addition, 

11 transmission lines are located near many of the existing wells (TCPA 2008).

12 In 1989, DOE operated a test geopressured-geothermal power plant at Pleasant Bayou, 

13 approximately 60 mi (97 km) northwest of STP. The 1 MW binary power plant operated for 

14 6 months and produced approximately 3,500 MWh of electricity (TCPA 2008). GEA (2007) 

15 estimates that electric power production potential from oil and gas wells in Texas could produce 

16 400 MWe in the near-term to over 2,000 MWe once the technology is refined and more 

17 widespread. Even if the oil and gas wells produced 2,000 MWe, this output would not be 

18 sufficient to make up for the 2,500 MWe produced by STP, Units 1 and 2. Additional capital and 

19 significant investment is required to develop and operate geopressured-geothermal power 

20 plants to produce a sufficient amount of baseload power.

21 As of 2008, no geothermal projects produced electricity on a commercial scale in Texas 

22 (TCPA 2008), but some potential exists for geopressured-geothermal power plants and 

23 low-temperature projects at smaller scales. Energy companies, Texas State Energy 

24 Conservation Office, and Southern Methodist University are currently assessing Texas’s 

25 potential for various forms of geothermal technology. A significant amount of investment would 

26 be required for geothermal energy to be used in Texas (TCPA 2008). Given the immature 

27 status of geothermal technology and the limited resource availability in Texas, the NRC 

28 concludes that geothermal energy is not a reasonable alternative to STP license renewal.

29 8.6.8 Municipal Solid Waste

30 Municipal-solid-waste combustors use three types of technologies—mass burn, modular, and 

31 refuse-derived fuel. Mass burning is used most frequently in the U.S. and involves little sorting, 

32 shredding, or separation. Consequently, toxic or hazardous components present in the waste 

33 stream are combusted, and toxic constituents are exhausted to the air or become part of the 

34 resulting solid wastes. Currently, approximately 86 waste-to-energy plants operate in the U.S. 

35 These plants have a generating capacity of 2,572 MWe, or an average of 30 MWe per plant 

36 (Michaels 2010). More than 85 average-sized plants would be necessary to provide the same 

37 level of output as STP.

38 Estimates in the GEIS suggest that the overall level of construction impact from a waste-fired 

39 plant would be approximately the same as that for a coal-fired power plant. Additionally, 

40 waste-fired plants have the same or greater operational impacts than coal-fired technologies 

41 (including impacts on the aquatic environment, air, and waste disposal). The initial capital costs 

42 for municipal solid-waste plants are greater than for comparable steam-turbine technology at 

43 coal-fired facilities or at wood-waste facilities because of the need for specialized waste 

44 separation and handling equipment (NRC 1996).

45 The decision to burn municipal waste to generate energy is driven by the need for an alternative 

46 to landfills rather than energy considerations. The use of landfills as a waste disposal option is 

47 likely to increase as energy prices increase; however, it is possible that municipal waste 
Environmental Impacts of Alternatives

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1 combustion facilities may become attractive again if there is a need for an alternative to landfills 

2 or an introduction of other regulatory incentives. 

3 Given the small average installed size of municipal solid-waste plants and the unfavorable 

4 regulatory environment, the NRC staff does not consider municipal solid-waste combustion to 

5 be a reasonable alternative to STP license renewal.

6 8.6.9 Biomass

7 Using biomass for energy consists of the direct burning of plant or animal matter, including 

8 wood waste, mill waste, agricultural residues, and energy crops. Biomass fuel provided less 

9 than 1 percent of electricity produced in the ERCOT region during 2010 (ERCOT 2011a). As of 

10 April 2011, applications for energy projects under review at ERCOT included 150 MW of 

11 proposed biomass-fuel projects (ERCOT 2011a). In Texas, the Red River Army Depot cofires 

12 biomass with fossil fuels (DOE 2004).

13 Biomass resources in Texas include crops (e.g., cotton, corn, and some soybeans), forests 

14 (especially in east Texas), and agricultural wastes (e.g., cattle manure, poultry litter, rice straw, 

15 peanut shells, cotton gin trash, and corn stover) (TCPA 2008). Houston Advanced Research 

16 Center estimated that Texas agricultural wastes could potentially produce 418.9 MWe

17 (HARC 2008).

18 In NUREG-1437, the NRC staff determined that a wood-burning facility can provide baseload 

19 power and operate with an average annual capacity factor of around 70 to 80 percent and with 

20 20 to 25 percent efficiency (NRC 1996). The fuels required are variable and site-specific. A 

21 significant impediment to the use of wood waste to generate electricity is the high cost of fuel 

22 delivery and high construction cost per megawatt of generating capacity. The larger woodwaste

23 power plants typically produce 40 to 50 MWe. Estimates in NUREG-1437 suggest that the 

24 overall level of construction impacts per megawatt of installed capacity would be approximately 

25 the same as that for a coal-fired plant, although facilities using wood waste for fuel would be 

26 built at smaller scales (NRC 1996). Similar to coal-fired plants, wood waste plants require large 

27 areas for fuel storage and processing and involve the same type of combustion equipment.

28 One of the largest wood-fired biomass power plants began operations in June 2012 in Sacul, 

29 Texas (Southern 2012). The 100 MWe wood-fired biomass power plant uses logging residue as 

30 its main fuel source. It also uses urban wood waste (TCPA 2008). The plant owner, Southern 

31 Power, estimated that the plant will require approximately 1 million tons of biomass per year, 

32 which it plans to procure within a 75-mi (121-km) radius of the project site (Southern 2009). 

33 Nearly 26 similarly sized facilities would be necessary to replace STP, Units 1 and 2.

34 Because of uncertainties associated with obtaining sufficient wood, wood waste, agricultural 

35 waste, or other biomass to fuel a baseload power plant, the ecological impacts of large-scale 

36 timber cutting (e.g., soil erosion and loss of wildlife habitat), and the relatively small size of wood 

37 generation plants, the NRC staff does not consider biomass fuel to be a reasonable alternative 

38 to STP license renewal.

39 8.6.10 Biofuels

40 Biofuels include biomass that has been refined into a liquid fuel, such as ethanol, or gasified 

41 (including crops and wood waste). The use of biofuels has increased during the past decade 

42 (TCPA 2008). However, the biofuels are primarily used in the transportation sector, and limited 

43 projects have been completed to use biofuels for energy generation.
Environmental Impacts of Alternatives

8-62

1 In the GEIS, the NRC staff indicated that none of the biofuel technologies progressed to the 

2 point of being competitive on a large scale or of being reliable enough to replace a baseload 

3 plant such as STP. After reevaluating current technologies, the NRC staff finds biofuel-fired 

4 alternatives as still unable to reliably replace the STP capacity. For this reason, the NRC staff 

5 does not consider biofuels to be a reasonable alternative to STP license renewal.

6 8.6.11 Oil-Fired Power

7 The EIA (2009) projects that oil-fired plants will account for very few of new generation capacity 

8 constructed in the U.S. during the 2011 to 2028 time period. Furthermore, EIA does not project 

9 that oil-fired power will account for any significant additions to capacity (EIA 2009).

10 The variable costs of oil-fired generation are greater than those of nuclear or coal-fired 

11 operations, and oil-fired generation has greater environmental impacts than natural gas-fired 

12 generation. In addition, EIA expects future increases in oil prices will make oil-fired generation 

13 increasingly more expensive (EIA 2009). The high cost of oil has prompted a steady decline in 

14 its use for electricity generation. Thus, the NRC staff does not consider oil-fired generation as a

15 reasonable alternative to STP license renewal.

16 8.6.12 Fuel Cells

17 Fuel cells oxidize fuels without combustion and its environmental side effects. Power is 

18 produced electrochemically by passing a hydrogen-rich fuel over an anode and passing air (or 

19 oxygen) over a cathode and then separating the two by an electrolyte. The only byproducts 

20 (depending on fuel characteristics) are heat, water, and carbon dioxide. Hydrogen fuel can 

21 come from a variety of hydrocarbon resources by subjecting them to steam under pressure. 

22 Natural gas is typically used as the source of hydrogen. 

23 At the present time, fuel cells are not technologically competitive with other alternatives for 

24 large-scale electricity generation. In addition, fuel cell units are likely to be small (the EIA (2009) 

25 reference plant is 10 MWe). While it may be possible to use a distributed array of fuel cells to 

26 provide an alternative to STP, it would be extremely costly to do so. Accordingly, the NRC staff 

27 does not consider fuel cells to be a reasonable alternative to STP license renewal.

28 8.6.13 Delayed Retirement

29 STPNOC is not aware of any of ERCOT’s electric generating plants currently proposed or 

30 planning for retirement, and additional capacity within the ERCOT region is not expected 

31 (STPNOC 2010a). Electric generating plants that may be retired by 2028 are likely to be older, 

32 less efficient, and without modern emissions controls. As a result, delayed retirement is not a 

33 reasonable alternative to license renewal.

34 In response to the requirements to reduce levels of sulfur dioxide in Texas as a part of the 

35 Cross-State Air Pollution Rule, ERCOT analyzed the impact of the reliability of the ERCOT grid 

36 (ERCOT 2011b). In this analysis, ERCOT noted that several facilities may need to idle during 

37 portions of the year. ERCOT did not state that any facilities would permanently close. 

38 Statements from power generation companies, such as Luminant, also suggest that facilities 

39 may need to remain idle in order to comply with the Cross-State Air Pollution Rule 

40 (Luminant 2011). The NRC is not aware of any facilities that are currently being proposed for 

41 permanent closure as a result of the Cross-State Air Pollution Rule.
Environmental Impacts of Alternatives

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8.7

2 This section examines the environmental effects that would occur if NRC takes no action. No 

3 action in this case means that NRC denies renewed operating licenses for STP, and the 

4 licenses expire at the end of the current terms, in 2027 and 2028. If NRC denies the renewed 

5 operating licenses, the plants will shut down at or before the end of the current licenses. After 

6 shutdown, plant operators will initiate decommissioning in accordance with 10 CFR 50.82.

1 No-Action Alternative

7 The NRC staff notes that the no-action alternative is the only alternative that is considered 

8 in-depth that does not satisfy the purpose and need for this SEIS because it neither provides 

9 power generation capacity nor does it meet the needs currently met by STP or the alternatives 

10 evaluated in Sections 8.1 through 8.5. Assuming that a need currently exists for the power 

11 generated by STP, the no-action alternative would require the appropriate energy-planning 

12 decisionmakers to rely on an alternative (or combination of them) to replace the capacity of STP 

13 or reduce the need for power.

14 This section addresses only those impacts that arise directly as a result of plant shutdown. The 

15 environmental impacts from decommissioning and related activities have been addressed in 

16 several other documents, including the Final Generic Environmental Impact Statement on 

17 Decommissioning of Nuclear Facilities, NUREG-0586, Supplement 1 (NRC 2002); Chapter 7 of 

18 the license renewal GEIS (NRC 1996); and Chapter 7 of this SEIS. These analyses either 

19 directly address or bound the environmental impacts of decommissioning whenever STPNOC 

20 ceases operating STP. In addition, the environmental impacts from potential replacement 

21 power alternatives are addressed in Sections 8.1 to 8.5.

22 The NRC staff notes that, even with renewed operating licenses, STP will eventually shut down, 

23 and the environmental effects addressed in this section will occur at that time. Since these 

24 effects have not otherwise been addressed in this SEIS, the impacts will be addressed in this 

25 section. As with decommissioning effects, the NRC staff expects the shutdown effects to be 

26 similar whether they occur at the end of the current licenses or at the end of renewed licenses.

27 8.7.1 Air Quality

28 When the STP stops operating, there will be a reduction in emissions from activities related to 

29 plant operation, such as use of diesel generators and employee vehicles. In Chapter 4, the 

30 NRC staff determined that these emissions would have a SMALL impact on air quality during 

31 the renewal term; therefore, if emissions decrease, the impact to air quality would also decrease 

32 and would be SMALL.

33 8.7.2 Surface Water Resources

34 The rate of consumptive use of surface water would decrease as STP is shut down and the 

35 reactor cooling system continues to remove the heat of decay. Wastewater discharges would 

36 also be reduced considerably. Shutdown would reduce the impacts on surface water use and 

37 quality and would remain SMALL.

38 8.7.3 Groundwater Resources

39 The use of groundwater would diminish as the plant workforce is drawn down and operations 

40 requiring groundwater cease. Some consumption of groundwater would continue to support the 

41 operation of service water and fire protection systems and to meet the potable and sanitary 

42 needs of the reduced workforce prior to decommissioning. Overall impacts would be less than 

43 during operations and would remain SMALL. 
Environmental Impacts of Alternatives

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1 8.7.4 Aquatic Ecology

2 If STP were to cease operating, impacts to aquatic ecology would decrease, as the plant would 

3 withdraw and discharge less water than it does during operations. Therefore, fewer organisms 

4 would be subject to the impingement, entrainment, and heat shock. Shutdown would reduce 

5 the impacts to aquatic ecology and would remain SMALL.

6 8.7.5 Terrestrial Ecology

7 Terrestrial ecology impacts would remain SMALL. No additional land disturbances on or off site 

8 would occur.

9 8.7.6 Human Health

10 Human health risks would be smaller following plant shutdown. The plant, which is currently 

11 operating within regulatory limits, would emit less gaseous and liquid radioactive material to the 

12 environment. In addition, following shutdown, the variety of potential accidents at the plant 

13 (radiological or industrial) would be reduced to a limited set associated with shutdown events 

14 and fuel handling and storage. In Chapter 4 of this SEIS, the NRC staff concluded that the 

15 impacts of continued plant operation on human health would be SMALL. In Chapter 5, the NRC 

16 staff concluded that the impacts of accidents during operation were SMALL. Therefore, as 

17 radioactive emissions to the environment decrease, and as likelihood and variety of accidents 

18 decrease following shutdown, the NRC staff concludes that the risk to human health following 

19 plant shutdown would be SMALL.

20 Noise caused by plant operations would cease; therefore, impacts from noise would be SMALL.

21 8.7.7 Land Use

22 STP shutdown would not affect onsite land use. Plant structures and other facilities would 

23 remain in place until decommissioning. Most transmission lines connected to STP would 

24 remain in service after the plant stops operating. Maintenance of most existing transmission 

25 lines would continue as before. Impacts on land use from plant shutdown would be SMALL.

26 8.7.8 Socioeconomics

27 STP shutdown would have an impact on socioeconomic conditions in the region around STP. 

28 Should the plant shut down, there would be immediate socioeconomic impact from loss of jobs 

29 (some, though not all, of the 1,378 employees would begin to leave), and tax payments may be 

30 reduced. As the majority of STP employees reside in Brazoria and Matagorda, socioeconomic 

31 impacts from plant shutdown would be concentrated in these counties, with a corresponding 

32 reduction in purchasing activity and tax contributions to the regional economy. Revenue losses 

33 from STP operations would directly affect Matagorda County and other local taxing districts and 

34 communities closest to, and most reliant on, the nuclear plant’s tax revenue. The impact of the 

35 job loss, however, may not be as noticeable given the amount of time required to decontaminate 

36 and decommission existing facilities and the proximity of STP to the Houston metropolitan area. 

37 The socioeconomic impacts of plan shutdown (which may not entirely cease until after 

38 decommissioning) would, depending on the jurisdiction, range from SMALL to MODERATE. 

39 8.7.9 Transportation

40 Traffic volumes on the roads in the vicinity of STP would be reduced after plant shutdown. Most 

41 of the reduction in traffic volume would be associated with the loss of jobs at the plant. 
Environmental Impacts of Alternatives

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1 Deliveries to the plant would be reduced until decommissioning. Transportation impacts would 

2 be SMALL as a result of plant shutdown. 

3 8.7.10 Aesthetics and Noise

4 Plant structures and other facilities would remain in place until decommissioning. Therefore, 

5 aesthetic and noise impacts of plant closure and the termination of operations would be SMALL.

6 8.7.11 Historic and Archaeological Resources

7 Impacts from the no-action alternative on historic and archaeological resources would be 

8 SMALL because no additional land disturbances would occur on or off the STP site. 

9 8.7.12 Environmental Justice

10 Impacts to minority and low-income populations would depend on the number of jobs and the 

11 amount of tax revenues lost by communities in the immediate vicinity of the plant after STP 

12 ceases operations. Closure of STP would reduce the overall number of jobs (there are currently 

13 1,378 people employed at the facility) and tax revenue for social services attributed to nuclear 

14 plant operations. Minority and low-income populations in the vicinity of STP could experience 

15 some socioeconomic effects from plant shutdown, but these effects would unlikely be high and 

16 adverse. See Appendix J of NUREG-0586, Supplement 1, Final Generic Environmental Impact 

17 Statement on Decommissioning of Nuclear Facilities Regarding the Decommissioning of 

18 Nuclear Power Reactors (NRC 2002), for additional discussion of these impacts.

19 8.7.13 Waste Management

20 If the no-action alternative were implemented, the generation of high-level waste would stop, 

21 and generation of low-level and mixed waste would decrease. Impacts from implementation of 

22 the no-action alternative are expected to be SMALL.

23 8.7.14 Summary of Impacts of No-Action Alternative

24 Table 8–7 provides a summary of the environmental impacts of the no-action alternative 

25 compared to continued operation of STP.

26 Table 8–7. Summary of Environmental Impacts of the No-Action 

27 Alternative Compared to Continued Operation of STP, Units 1 and 2

Category No-action Alternative Continued STP Operation

Air quality SMALL SMALL

Surface water SMALL SMALL

Groundwater SMALL SMALL

Aquatic resources SMALL SMALL

Terrestrial resources SMALL SMALL

Human health SMALL SMALL to MODERATE

Land use SMALL SMALL

Socioeconomics SMALL to MODERATE SMALL
Environmental Impacts of Alternatives

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Category No-action Alternative Continued STP Operation

Transportation SMALL SMALL

Aesthetics SMALL SMALL

Historic & archaeological SMALL SMALL

Waste management SMALL SMALL

8.8

2 In this chapter, the NRC staff considered the following alternatives to STP license renewal: new 

3 nuclear generation; NGCC generation; supercritical coal-fired generation; a combination 

4 alternative of natural gas, wind, and energy efficiency and conservation; and a purchased-power 

5 alternative. No action by NRC and its effects were also considered. The impacts for STP 

license renewal and for all alternatives to STP license renewal are summarized in

1 Alternatives Summary

6 Table 8–8. 

7 In conclusion, the environmentally preferred alternative is the license renewal of STP. All other 

8 alternatives capable of meeting the needs currently served by STP entail potentially greater 

9 impacts than the proposed action of license renewal of STP. In order to make up the lost 

10 generation if license renewal is denied, the no-action alternative necessitates the 

11 implementation of one or a combination of alternatives, all of which have greater impacts than 

12 the proposed action. Hence, the NRC staff concludes that the no-action alternative will have 

13 environmental impacts greater than or equal to the proposed license renewal action.

14
8-67

Table 8–8. Summary of Environmental Impacts of Proposed Action and Alternatives 1 

Alternative

Impact Area

Air QualityGroundwater and Surface waterAquatic and Terrestrial ResourcesHuman HealthLand Use

omics Socioecon

(including 

 & Transportation

Aesthetics)

& Archaeological 

Historic Resources

License renewal SMALL SMALL SMALL SMALL to 

MODERATE SMALL SMALL SMALL 

New nuclear at STP 

site SMALL SMALL SMALL SMALL SMALL SMALL to LARGE SMALL 

NGCC at the STP 

site

SMALL to 

MODERATE SMALL SMALL SMALL SMALL to 

MODERATE

SMALL to 

MODERATE SMALL 

Supercritical coal at 

STP site MODERATE SMALL SMALL to MODERATE SMALL MODERATE SMALL to LARGE SMALL 

Combination of 

alternatives

SMALL to 

MODERATE SMALL SMALL to MODERATE SMALL SMALL to MODERATE

SMALL to 

LARGE

SMALL 

MODER

Purchased power SMALL to

MODERATE SMALL SMALL to MODERATE SMALL SMALL to MODERATE

SMALL to

LARGE

SMALL 

MODER

No-action alternative SMALL SMALL SMALL SMALL SMALL SMALL to 

MODERATE SMALL 

 2 
Environmental Impacts of Alternatives

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8.9

2 10 CFR Part 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental 

3 protection regulations for domestic licensing and related regulatory functions.”

1 References

4 65 FR 79825. U.S. Environmental Protection Agency. Regulatory finding on the emissions of 

5 hazardous air pollutants from electric utility steam generating units. Federal Register

6 65(245): 79825–79831. December 20, 2000.

7 Archer CL, Jacobson MZ. 2007. Supplying baseload power and reducing transmission 

8 requirements by interconnecting wind farms. Journal of Applied Meteorology and 

9 Climatology 46: 1701–1717.

10 [DOE] U.S. Department of Energy. 2004. Biomass Cofiring in Coal-Fired Boilers. 

11 Washington, DC: Federal Energy Management Program/DOE. DOE/EE-0288. Available at 

12 <http://www1.eere.energy.gov/femp/pdfs/fta_biomass_cofiring.pdf> (accessed 

13 21 November 2011).

14 [DOE] U.S. Department of Energy. 2007. Cost and Performance Baseline for Fossil Energy 

15 Plants. DOE/NETL-2007/1281. Volume 1. May 2007.

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42 17 October 2011).
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2 Nonattainment Areas for All Criteria Pollutants.” August 30, 2011. Available at 

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7 <http://www.ercot.com/about/profile/> (accessed 18 August 2011).

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9 Rule on the ERCOT System.” September 1, 2011. Available at: 

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11 (accessed 17 November 2011).

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13 Limerick Generating Station, Units 1 and 2. 

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15 <http://www.ge-energy.com/products_and_services/index.jsp> (accessed 17 October 2011).

16 [GEA]. Geothermal Energy Association 2007. An Assessment of Geothermal Resource 

17 Development Needs in the Western United States. Washington, DC: GEA. January 2007. 

18 Available at <http://www.geo-energy.org/reports/States%20Guide.pdf> (accessed 

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45 Washington, DC: DOE/NETL. DOE/NETL-2007/1281. ADAMS No. ML100640755.
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10 Nuclear Power Reactors. Washington, DC: NRC. NUREG-0586, Supplement 1. 

11 November 2002. ADAMS Nos. ML023470304 and ML023500295.

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14 Unit 1. Washington, DC: NRC. NUREG-1437, Supplement 33.

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16 Combined Licenses (COLs) for South Texas Project Electric Generating Station, Units 3 and 4. 

17 Washington, DC: NRC. NUREG-1937. February 2011. ADAMS No. ML11049A000.

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28 the United States; Assessment of Opportunities and Barriers. Golden, CO: NREL. Technical 

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31 Home Energy Assistance Program Assessment. ADAMS No. ML082880730.

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33 Energy Storage, Summit County.” Available at 

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36 [Southern] Southern Company. 2009. Southern Company Breaks Ground on Biomass Plant. 

37 Atlanta, GA: Southern Company. November 10, 2009. ADAMS No. ML100700543.

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43 Georgia Coast. Atlanta, GA: GIT. Available at 

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45 28 November 2011).
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2 STPNOC, to B Martin, THC. Subject: South Texas Project, Units 3 and 4. December 12, 2006. 

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5 Renewal Stage South Texas Project, Units 1 and 2. September 2010. ADAMS 

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8 Units 3 and 4, Combined License Application. Bay City, TX: STPNOC. Part 3, “Environmental 

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10 Succar S, Williams RH. 2008. Compressed Air Energy Storage: Theory, Resources, and 

11 Applications for Wind Power. Princeton, NJ: Princeton University Energy Systems Analysis 

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13 17 October 2011).

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15 No. WQ0001908000. Austin, TX.

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17 Applications.” Available at 

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21 Available at <http://www.window.state.tx.us/specialrpt/energy/> (accessed 17 October 2011).

22 [THC]. Texas Historical Commission. 2007. Response from WA Martin for FL Oaks, THC, to 

23 SL Dannhardt, STPNOC. Stamped Reply: “No Historic Properties Affected Project May 

24 Proceed.” January 19, 2007. ADAMS No. ML092100145.

25 [TSECO]. Texas State Energy Conservation Office. 2008. Wind Energy Transmission. 

26 Austin, TX. ADAMS No. ML100700550.

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28 Austin, TX: TWDB. Document No. GP-8-1.

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30 Available at <http://www.vera.com/re_b_psdoc_07.htm.> (accessed 17 October 2011).

9-1 

1 9.0 CONCLUSION

2 This supplemental environmental impact statement (SEIS) contains the environmental review of 

3 STP Nuclear Operating Company’s (STPNOC’s) application for renewed operating licenses for 

4 South Texas Project, Units 1 and 2 (STP) as required by Title 10 of the U.S. Code of Federal 

5 Regulations (CFR) Part 51 (10 CFR Part 51), the U.S. Nuclear Regulatory Commission’s 

6 (NRC’s) regulations that implement the National Environmental Policy Act (NEPA). This chapter 

7 presents conclusions and recommendations from the site-specific environmental review of STP 

8 and summarizes site-specific environmental issues of license renewal that the NRC staff (staff) 

9 identified during the review. Section 9.1 summarizes the environmental impacts of license 

10 renewal; Section 9.2 presents a comparison of the environmental impacts of license renewal 

11 and energy alternatives; Section 9.3 discusses unavoidable impacts of license renewal, energy 

12 alternatives, and resource commitments; and Section 9.4 presents conclusions and NRC staff 

13 (staff) recommendations.

9.1

15 Based on the staff’s review of site-specific environmental impacts of license renewal presented 

16 in this SEIS, the staff concludes that issuing renewed licenses would have mostly SMALL 

17 impacts. The site-specific review included 12 Category 2 issues and 2 uncategorized issues. 

18 The staff considered mitigation measures for each Category 2 issue, as applicable. The staff 

19 concluded that no additional mitigation measure is warranted. 

14 Environmental Impacts of License Renewal

20 Additionally, the staff independently reviewed STPNOC’s SAMA. The staff agrees with 

21 STPNOC’s conclusion that none of the candidate SAMAs are potentially cost-beneficial. 

22 The staff also considered cumulative impacts of past, present, and reasonably foreseeable 

23 future actions, regardless of what agency (Federal or non-Federal) or person undertakes them. 

24 The staff concluded in Section 4.11 that cumulative impacts would be SMALL to MODERATE 

25 depending on the resource area. However, except for the electromagnetic fields-acute effects, 

26 the incremental contribution from STP during the period of extended operation would be 

27 SMALL.

9.2

29 In the conclusion to Chapter 8, the staff considered the following alternatives to STP license 

30 renewal: 

28 Comparison of Alternatives

31 • new nuclear generation, 

32 • natural gas-fired combined-cycle generation (NGCC), 

33 • supercritical coal-fired generation, 

34 • combination alternative (the combination includes 640 MWe supplied by one 

35 NGCC unit; 1,620 MWe supplied by wind energy projects; and 300 MWe of 

36 energy conservation and efficiency, also known as demand-side 

37 management), and 

38 • purchased power. 

39 In addition, the staff also considered many other alternatives that were subsequently dismissed 

40 for reasons of technical, resource availability, or commercial limitations.
Conclusion

9-2 

1 As summarized in Table 8–7, the staff concluded that the alternatives of supercritical coal at 

2 STP, purchased power, or combination alternative would have environmental impacts ranging 

3 from SMALL to LARGE. The alternatives of new nuclear at STP, NGCC at STP, and the 

4 no-action alternative would have impacts ranging from SMALL to MODERATE. In comparison 

5 to other alternatives, the STP license renewal alternative would have mostly SMALL impacts in 

6 all areas of the environmental analysis. Based on the staff’s independent review, the staff 

7 concluded that the STP license renewal is the environmentally preferred alternative. 

9.3

9 9.3.1 Unavoidable Adverse Environmental Impacts 

8 Resource Commitments

10 Unavoidable adverse environmental impacts are impacts that would occur after implementation 

11 of all workable mitigation measures. Carrying out any of the energy alternatives considered in 

12 this SEIS, including the proposed action, would result in some unavoidable adverse 

13 environmental impacts.

14 Minor unavoidable adverse impacts on air quality would occur due to emission and release of 

15 various chemical and radiological constituents from power plant operations. Nonradiological 

16 emissions resulting from power plant operations are expected to comply with U.S. 

17 Environmental Protection Agency (EPA) emissions standards, though the alternative of 

18 operating a fossil-fueled power plant in some areas may worsen existing attainment issues. 

19 Chemical and radiological emissions would not exceed the national emission standards for 

20 hazardous air pollutants.

21 During nuclear power plant operations, workers and members of the public would face 

22 unavoidable exposure to radiation and hazardous and toxic chemicals. Workers would be

23 exposed to radiation and chemicals associated with routine plant operations and the handling of 

24 nuclear fuel and waste material. Workers would have higher levels of exposure than members 

25 of the public, but doses would be administratively controlled and would not exceed standards or 

26 administrative control limits. In comparison, the alternatives involving the construction and 

27 operation of a non-nuclear power generating facility would also result in unavoidable exposure 

28 to hazardous and toxic chemicals to workers and the public.

29 The generation of spent nuclear fuel and waste material, including low-level radioactive waste, 

30 hazardous waste, and nonhazardous waste would be unavoidable. Hazardous and 

31 nonhazardous wastes would be generated at non-nuclear power generating facilities. Wastes 

32 generated during plant operations would be collected, stored, and shipped for suitable 

33 treatment, recycling, or disposal in accordance with applicable Federal and state regulations. 

34 Due to the costs of handling these materials, power plant operators would be expected to carry 

35 out all activities and optimize all operations in a way that generates the smallest amount of 

36 waste possible.

37 9.3.2 Short-Term Versus Long-Term Productivity

38 The operation of power generating facilities would result in short-term uses of the environment, 

39 as described in Chapters 4, 5, 6, 7, and 8. “Short-term” is the period of time that continued 

40 power generating activities take place.

41 Power plant operations require short-term use of the environment and commitment of resources 

42 and commit certain resources (e.g., land and energy), indefinitely or permanently. Certain 

43 short-term resource commitments are substantially greater under most energy alternatives, 

44 including license renewal, than under the no-action alternative because of the continued 
Conclusion

9-3 

1 generation of electrical power and the continued use of generating sites and associated 

2 infrastructure. During operations, all energy alternatives entail similar relationships between 

3 local short-term uses of the environment and the maintenance and enhancement of long-term 

4 productivity.

5 Air emissions from power plant operations introduce small amounts of radiological and 

6 nonradiological constituents to the region around the plant site. Over time, these emissions 

7 would result in increased concentrations and exposure, but they are not expected to impact air 

8 quality or radiation exposure to the extent that public health and long-term productivity of the 

9 environment would be impaired.

10 Continued employment, expenditures, and tax revenues generated during power plant 

11 operations directly benefit local, regional, and state economies over the short term. Local 

12 governments investing project-generated tax revenues into infrastructure and other required 

13 services could enhance economic productivity over the long term.

14 The management and disposal of spent nuclear fuel, low-level radioactive waste, hazardous 

15 waste, and nonhazardous waste requires an increase in energy and consumes space at 

16 treatment, storage, or disposal facilities. Regardless of the location, the use of land to meet 

17 waste disposal needs would reduce the long-term productivity of the land.

18 Power plant facilities are committed to electricity production over the short term. After 

19 decommissioning these facilities and restoring the area, the land could be available for other 

20 future productive uses.

21 9.3.3 Irreversible and Irretrievable Commitments of Resources

22 This section describes the irreversible and irretrievable commitment of resources that have 

23 been noted in this SEIS. Resources are irreversible when primary or secondary impacts limit 

24 the future options for a resource. An irretrievable commitment refers to the use or consumption 

25 of resources that are neither renewable nor recoverable for future use. Irreversible and 

26 irretrievable commitment of resources for electrical power generation include the commitment of 

27 land, water, energy, raw materials, and other natural and man-made resources required for 

28 power plant operations. In general, the commitment of capital, energy, labor, and material 

29 resources are also irreversible.

30 The implementation of any of the energy alternatives considered in this SEIS would entail the 

31 irreversible and irretrievable commitment of energy, water, chemicals, and—in some cases— 

32 fossil fuels. These resources would be committed during the license renewal term and over the 

33 entire life cycle of the power plant, and they would be unrecoverable.

34 Energy expended would be in the form of fuel for equipment, vehicles, and power plant 

35 operations and electricity for equipment and facility operations. Electricity and fuel would be 

36 purchased from offsite commercial sources. Water would be obtained from existing water 

37 supply systems. These resources are readily available, and the amounts required are not 

38 expected to deplete available supplies or exceed available system capacities.

9.4

40 The NRC’s preliminary recommendation is that the adverse environmental impacts of license 

41 renewal for STP are not great enough to deny the option of license renewal for energy-planning 

42 decisionmakers. The NRC staff based this recommendation on the following: 

39 Recommendations
Conclusion

9-4 

1 • the analysis and findings in NUREG-1437, Volumes 1 and 2, Generic 

2 Environmental Impact Statement for License Renewal of Nuclear Plants, 

3 • the Environmental Report (ER) submitted by STPNOC,

4 • consultation with Federal, state, and local agencies,

5 • the NRC’s environmental review, and

6 • consideration of public comments received during the scoping process. 
10-1 

1 10.0 LIST OF PREPARERS

2 This supplemental environmental impact statement (SEIS) was prepared by members of the 

3 Office of Nuclear Reactor Regulation (NRR) with assistance from other U.S. Nuclear Regulatory 

4 Commission (NRC) organizations and contract support from Pacific Northwest National 

5 Laboratory (PNNL). Table 10–1 lists the NRC staff who contributed to the development of the 

6 SEIS. PNNL provides contract support for cultural resource, hydrology, and severe accident 

7 mitigation alternative (SAMA) reviews.

8 Table 10–1. List of Preparers

Name Affiliation Function or Expertise

NRC

D. Wrona NRR Management oversight

B. Pham NRR Management oversight

A. Imboden NRR Management oversight

T. Tran NRR Project management

A. BeBault NRR Socioeconomic, environmental justice, 

land use, and terrestrial

S. Klementowicz NRR Human health

K. Folk NRR Hydrology and alternatives

M. Moser NRR Aquatic and marine ecology and 

alternatives

B. Balsam NRR Aquatic and marine ecology and terrestrial

A. Travers NRR Cultural resource

J. Rikhoff NRR Socioeconomic, environmental justice, and 

land use

W. Rautzen NRR Air quality and meteorology (climatology)

J. Dozier NRR SAMA

National Laboratory Personnel (a)

S. Short PNNL SAMA

R. Schmitt PNNL SAMA

C. Kincaid PNNL Hydrology

R. Prasad PNNL Hydrology

T. O’Neil PNNL Cultural resource

(a) PNNL is operated by Battelle for the U.S. Department of Energy.

11-1 

1 11.0 LIST OF AGENCIES, ORGANIZATIONS, AND PERSONS TO 

2 WHOM COPIES OF THIS SUPPLEMENTAL ENVIRONMENTAL IMPACT 

3 STATEMENT ARE SENT

Name Affiliation 

D. Klima Advisory Council on Historic Preservation 

O. Sylestine Tribal Nation—Alabama–Coushatta Tribe 

B. Horse Tribal Nation—Kiowa Tribe of Oklahoma 

R. Toahty Tribal Nation—Comanche Nation 

M. Orms U.S. Fish & Wildlife Service 

D. Bernhart National Marine Fisheries Service 

K. Boydston Texas Parks & Wildlife Department 

M. Wolfe State Historic Preservation Officer 

A. Street Tribal Nation—Tonkawa Tribe of Oklahoma 

M. Blount Tribal Nation—Apalachicola Band of Creek Indians 

B. Barcena Jr. Tribal Nation—Lipan Apache Tribe of Texas 

D. Romero Jr. Tribal Nation—Lipan Apache Band of Texas 

J. Mendoza Tribal Nation—Pamaque Clan of Coahuila Y Tejas 

R. Hernandez Tribal Nation—Tap PilamCoahuiltecan Nation 

J. Garza Jr. Tribal Nation—Kickapoo Traditional Council 

J. Loera Tribal Nation—Ysleta del Sur Pueblo 

N. Hudgins Coastal Plains Groundwater Conservation District

L. Gaul Texas Department of State Health Services 

EIS Scoping Participant* Affiliation & Address

N. McDonald Matagorda County Judge

1700 7th Street, Room 301, Bay City, TX 77414

J. Gibean Matagorda County Resident

25000 Hwy 35 South, Palacios, TX 77465

S. Dancer S.T.A.R.E

PO Box 209, Blessing, TX 77419

R. Malachowski McDonalds

PO Box 1110, Bay City, TX 77404

M. Butter Matagorda County Economic Development Corporation

2200 7th Street, Suite 302, Bay City, TX 77414
List of Agencies, Organizations, and Persons to Whom Copies of This Supplemental 

Environmental Impact Statement Are Sent

11-2 

L. Bracken Realtor

2055 Ave F, Bay City, TX 77414

B. Watts Matagorda County EMC

2200 7th St, Bay City, TX 77414

M. B. Johnston Palacios City

PO Box 782, Palacios, TX 77465

A. Acosta Matagorda Advocate

Victoria Matagorda Advocate Newspaper

C. Dunohue WCJC Nuke Program

2919 Ave J, Bay City, TX 77414

M. Crews Matagorda County Resident

2200 Golden Ave, Bay City, TX 77414

C. Corporon South Texas Project Nuclear Operating Company

2608 Wofford Rd, Bay City, TX 77414

K. Hadden SEED Coalition

1303 San Antonio Suite 100, Austin, TX 78701

D. Kile U.S. Congressman Ron Paul

122 W Way Suite 301, Lake Jackson, TX 77566

A. Moore Bay City Public Library

1100 7th Street, Bay City, TX 77414

EIS Filing Section U.S. Environmental Protection Agency

1200 Pennsylvania Ave NW, Washington, D.C. 20004

* requested to be on the mailing list

 1 
12-1 

12.0 INDEX

accidents, xiii, xviii, 4-44, 4-50, 5-1, 5-2, 

5-3, 8-64, A-4, A-16, B-8, F-16, F-28

Advisory Council on Historic 

Preservation (ACHP), xxii, 1-5, 4-43, E-1, 

aesthetic, 4-45, 8-11, 8-12, 8-23, 8-36, 

8-49, 8-53, 8-65

alternatives, v, xviii, xix, 1-5, 4-52, 4-61, 

5-2, 5-3, 6-3, 6-4, 6-5, 8-1, 8-2, 8-3, 8-10, 

8-12, 8-21, 8-30, 8-31, 8-34, 8-39, 8-46, 

8-53, 8-55, 8-56, 8-62, 8-63, 8-66, 8-67, 9-1, 

9-2, 9-3, 10-1, A-1, A-4, A- 5, A-7, A-8, 

A-11, B-8, F-1, F-2, F-22, F-23, F-32

archaeological resources, xviii, 1-5, 2-71, 

2-72, 3-2, 4-40, 4-67, 4-68, 4-69, 8-12, 8-13, 

8-23, 8-24, 8-36, 8-37, 8-49, 8-50, 8-54, 

8-65, B-8, D-1 

biota, 4-11, 4-14, 4-59, 4-60, 8-8, A-14, B-2 

boiling water reactor (BWR), A-16, F-21

burnup, 2-1, B-10

chronic effects, xviii, 1-3, 4-33, 4-39, B- 7 

Clean Air Act (CAA), xxii, 8-16, 8-17, 8-26, 

8-28, 8-29, 8-30, 8-40, 8-41

closed-cycle cooling, 4-18, 4-24, B-4, B-5 

Coastal Zone Management Act (CZMA), 

1-6, 2-73

cooling system, xvii, 1-4, 2-17, 4-11, 4-12, 

4-18, 4-20, 4-22, 4-24, 8-3, 8-4, 8-8, 8-20, 

8-32, 8-44, 8-63, B-3, B-4, F-7 

core damage frequency, xxii, 5-4–5-7, 

5-9–5-11, F-1–F-9, F-11, F-13–F-16, F-20–

F-23, F-26–F-30, F-33

Council on Environmental Quality (CEQ), 

1-3, 4-45, 4-70

critical habitat, 2-43, 2-49, 2-50, 2-74, 

4-31, 8-9, C-5 

cultural resources, 2-71, 2-72, 2-79, 4-43, 

4-44, 4-45, 4-67, 4-74, 8-12, 8-13, 8-23, 

8-24, 8-36, 8-37, 8-49, 8-50, 8-53, C-1 

Decommissioning, viii, xiii, 7-1, 7-2, 8-63, 

8-65, 8-70, B-10

design-basis accident, xxiii, 4-50, 5-1, B-8 

discharges, 2-5, 2-7–2-9, 2-17–2-19, 2-20, 

4-8, 4-10, 4-18, 4-22–4-24, 4-35–4-37, 4-60, 

8-8, 8-15, 8-19, 8-20, 8-26, 8-31, 8-32, 8-43, 

8-44, 8-63, B-2, B-3, C-3 

dose, 2-2, 2-3, 4-36, 4-37, 4-64, 4-65, 4-69, 

5-7, 5-8, 5-10, A-14, B-6, B-8, F-1, F-6, F-7, 

F-16– F-19, F-21, F-23, F-26–F-28

education, 3-2, 4-40, A-9, A-10, A-11, B-7 

electromagnetic fields, 1-3, 4-26, 4-39, 

4-65, 9-1, B-5, B-7 

Endangered Species Act (ESA), xii, xxiv, 

2-47, 2-49, 2-50, 2-51, 2-53, 4-26, 4-27

entrainment, 2-56, 4-12, 4-13, 4-15, 4-16, 

4-18–4-20, 4-22, 4-25, 4-32, 4-59, 4-60, 8-8, 

8-9, 8-20, 8-32, 8-44, 8-64, B-2, B-3 

essential fish habitat, xii, xxiii, 2-54, 2-56, 

2-77, 4-19, 4-32, 4-73, 

Generic Environmental Impact Statement 

(GEIS), xiii, xvi, xvii, xix, xxiv, 1-3, 1-4, 1-5, 

1-6, 2-62, 3-1, 3-2, 4-1, 4-2, 4-5, 4-6, 4-8, 

4-11, 4-25, 4-26, 4-33, 4-34, 4-38–4-42, 

4-51, 4-52, 4-66, 5-1, 5-2, 6-1, 6-2, 6-3, 7-1, 

7-2, 8-1, 8-2, 8-10, 8-14, 8-15, 8-21, 8-22, 

8-25, 8-27, 8-34, 8-35, 8-41, 8-45–8-48, 

8-56, 8-59, 8-60, 8-62, 8-63, A-1, B-8 

greenhouse gases, 8-6, 8-15, 8-17, 8-30, 

8-41, 8-42, 

groundwater, 2-9, 2-10, 2-12, 2-16, 2-19–

2-23, 2-36, 2-37, 2-60, 3-1, 4-5–4-11, 4-33, 

4-34, 4-35, 4-51, 4-55, 4-57, 4-58, 4-60, 

4-68, 5-2, 8-3, 8-7, 8-8, 8-19, 8-31, 8-32, 

8-44, 8-53, 8-55, 8-63, B-4, B-5, B-8, C-1 

hazardous waste, 2-4, 2-5, 9-2, 9-3, C-4, 

C-3, C-4 

heat shock, 4-22, 4-59, 8-9, 8-20, 8-32, 

8-64, B-3 

high-level waste, xvii, 1-4, 6-1, 6-2, 8-14, 

8-65, A-18, B-8, B-9, B-10
0BIndex

12-2 

impingement, xviii, 2-56, 4-12–4-15, 4-17–

4-20, 4-22, 4-25, 4-32, 4-59, 4-60, 8-8, 8-9, 

8-20, 8-32, 8-44, 8-64, B-2, B-3 

low-level waste, xxv, 2-4, 6-1, 8-14, B-9 

maximum occupational doses, 4-34, B-7 

mitigation, xvii, xviii, xxviii, 1-3, 1-4, 1-5,

4-1, 4-11, 4-25, 4-34, 4-39, 4-66, 5-2, 7-1, 

7-2, 8-12, 8-24, 8-37, 8-50, 9-1, 9-2, 10-1, 

E-5, F-1, F-14

mixed waste, 8-14, 8-65, B-9 

National Environmental Policy Act 

(NEPA), xiii, xvi, xxvii, 1-1, 1-7, 2-70, 2-72, 

2-78, 3-3, 4-32, 4-43, 4-44, 4-45, 4-59, 4-71, 

4-73, 4-74, 5-1, 6-2, 6-9, 7-2, 8-1, 8-70, 9-1, 

B-1, B-9, E-7 

National Marine Fisheries Service 

(NMFS), xxvii, 1-5, 2-47, 2-74, 2-77, 2-78, 

4-26, 4-73, 11-1, D-1, D-2 

National Pollutant Discharge Elimination 

System (NPDES), xxvii, 4-20, 8-7, 8-19, 

8-32, B-2, C-1, C-3 

no-action alternative, v, xix, 8-2, 8-63, 

8-65, 8-66, 9-2 

nonattainment, 4-54

once-through cooling, 4-19, 4-24 , B-2, 

B-3 

radon, 4-34, B-8 

reactor, xvi, xvii, xxii, xxvii, xxviii, 2-1, 2-2, 

2-4, 2-6, 2-13, 2-16, 2-23, 3-1, 3-3, 4-37, 

4-41, 4-65, 4-69, 5-1, 5-2, 5-3, 5-10, 6-2, 

6-4, 7-1, 8-4, 8-7, 8-11, 8-12, 8-23, 8-36, 

8-63, A-14, A-16, A-17, B-4, B-8, F-16, 

F-18, F-29

refurbishment, 2-14, 2-70, 3-1, 3-2, 4-31, 

4-33, 4-37, 4-41, 4-44, 4-54, B-1, B-2, B-4– 

B-8, C-3, F-28

salinity gradients, 4-2, B-1 

scoping, v, xvi, xvii, xx, 1-2, 1-5, 4-1, 4-2, 

4-5, 4-11, 4-25, 4-33, 4-34, 4-40, 4-44, 4-53, 

5-2, 6-2, 7-2, 9-4, A-1, A-4, E-1–E-4 

Severe Accident Mitigation Alternatives 

(SAMA), xiii, xiv, xxviii, 5-3, 5-4, 5-8, 5-9, 

5-10, 5-11, 5-13, 9-1, 10-1, F-1, F-2, F-3, 

F-7, F-8, F-11, F-12, F-14–F-35, F-37

severe accidents, xiii, xviii, 4-50, 5-1, 5-2, 

5-3, A-16, B-8, F-13, F-27, F-28, F-29

solid waste, xix, xxix, 2-1, 2-2, 2-3, 2-4, 

6-1, 7-2, 8-2, 8-27, 8-31, 8-60, A-8, B-10, 

C-1 

spent fuel, xvii, 1-4, 2-2, 4-65, 6-1, 6-2, 

A-12, A-18, B- 8, B-9, B-10

State Historic Preservation Officer 

(SHPO), xxviii, 1-6, 2-78, 4-43, 4-44, 4-73, 

8-12, 8-13, 8-23, 8-24, 8-36, 8-37, 8-49, 

8-50, E-2 

State Pollutant Discharge Elimination 

System, xxviii, C-1 

surface water, 2-10, 2-18, 2-21, 3-1, 4-2, 

4-3, 4-5, 4-8, 4-9, 4-29, 4-34, 4-50, 4-51, 

4-56, 4-57, 4-60, 4-63, 4-68, 8-3, 8-6, 8-7, 

8-18–8-20, 8-31–8-33, 8-43, 8-44, 8-53, 

8-63, B-1, B- 4, C-1 

transmission lines, 2-7, 2-43, 2-49, 2-51, 

2-58, 4-2, 4-11, 4-31, 4-32, 4-38–4-40, 4-43, 

4-61, 4-63–4-67, 8-39, 8-43, 8-45, 8-46, 

8-53, 8-56, 8-58, 8-60, 8-64, B-6, B-8 

tritium, 2-22, 2-23, 4-9, 4-10, 4-33, 4-35, 

4-57, A-14, A-17

U.S. Department of Energy (DOE), xxiii, 

4-35, 4-36, 4-39, 8-2, 8-3, 8-18, 8-27, 8-39, 

8-42, 8-57, 8-60, 8-61, 8-68, 8-69

U.S. Environmental Protection Agency 

(EPA), xxiii, 2-1, 2-4–2-6, 2-14, 2-22, 2-23, 

2-37, 2-38, 2-60, 2-62, 2-75, 2-76, 2-81, 4-9, 

4-10, 4-12, 4-13, 4-18, 4-20, 4-22, 4-23, 

4-35, 4-37, 4-54, 4-57, 4-59, 4-64, 4-65, 

4-69, 4-71, 8-2, 8-5, 8-16–8-18, 8-26, 8-28–

8-30, 8-34, 8-40, 8-41, 8-42, 8-68, 8-69, 9-2, 

A-14, A-15, A-17, C-1–C-5 

U.S. Fish and Wildlife Service (FWS), 1-6 

uranium, 2-1, 2-2, 4, 5, 18, 19, 4-65, 6-1, 

6-2, 6-4–6-8, 8-10, 8-21, 8-34, 8-47 , A-4, 

A-5, A-18, A-19, B-8, B-9, B-10 

wastewater, 2-5, 2-8, 2-73, 4-2, 4-63, 8-60, 

B-2, C-3 

Yucca Mountain project, B-10
APPENDIX A 

COMMENTS RECEIVED ON THE STP ENVIRONMENTAL REVIEW

A-1 

1 COMMENTS RECEIVED ON THE STP ENVIRONMENTAL REVIEW

2 A.1 Comments Received During the Scoping Period

3 The scoping process began on January 31, 2011, with the publication of the U.S. Nuclear 

4 Regulatory Commission’s (NRC’s) Notice of Intent to conduct scoping in the Federal Register

5 (76 FR 5410). The scoping process included two public meetings held at the Bay City Civic 

6 Center in Bay City, Texas, on March 2, 2011. Approximately 60 members of the public attended 

7 the meetings. After the NRC’s prepared statements pertaining to the license renewal process, 

8 the meetings were open for public comments. Attendees provided oral statements that were 

9 recorded and transcribed by a certified court reporter. Any written statements submitted at the 

10 public meeting are documented in the transcript of the meetings. Transcripts of the two 

11 meetings are an attachment to the Scoping Meeting Summary, dated May 19, 2011 

12 (Agencywide Documents Access and Management System (ADAMS) No. ML110770661). In 

13 addition to the comments received during the public meetings, comments were also received 

14 electronically and through the mail.

15 Each commenter was given a unique identifier, so every comment could be traced back to its 

16 author. Table A–1 identifies the individuals who provided comments applicable to the 

17 environmental review and the Commenter ID associated with each person’s set of comments. 

18 The individuals are listed in the order in which they spoke at the public meeting and in numerical

19 order for the comments received by letters or e-mails. 

20 Specific comments were categorized and consolidated by topic. Comments with similar specific 

21 objectives were combined to capture the common essential issues raised by participants. 

22 Comments fall into one of the following general groups: 

23 • Specific comments that address environmental issues within the purview of 

24 the NRC environmental regulations related to license renewal. These 

25 comments address Category 1 (generic) or Category 2 (site-specific) issues 

26 identified in NUREG-1437, Generic Environmental Impact Statement for 

27 License Renewal of Nuclear Plants (GEIS) or issues not addressed in the

28 GEIS. The comments also address alternatives to license renewal and 

29 related Federal actions. 

30 • General comments in support of or opposed to nuclear power or license 

31 renewal or comments regarding the renewal process, the NRC’s regulations, 

32 and the regulatory process. 

33 • Comments that address issues that do not fall within or are specifically 

34 excluded from the purview of NRC environmental regulations related to 

35 license renewal. These comments typically address issues such as the need 

36 for power, emergency preparedness, security, current operational safety 

37 issues, and safety issues related to operation during the renewal period.

38 Table A–1. Individuals Providing Comments During the Scoping Comment Period

Commenter Commenter ID Affiliation (if stated) ADAMS No.

Randy Weber STP 1 State Representative ML110840441

Judge Nate McDonald STP 2 Matagorda County judge and local 

emergency response official ML110840441
Appendix A

A-2 

Commenter Commenter ID Affiliation (if stated) ADAMS No.

Mark Bricker STP 3 Bay City Mayor ML110840441

Ron Paul’s office STP 4 U.S. congressman ML110840441

Ed Halpin STP 5 STP CEO ML110840441

Carolyn Thames STP 6 Bay city council member ML110840441

Don Booth STP 7 Director local 211 Pipefitter union of 3,000 ML110840441

Cheryl Stewart STP 8

Bay City Community Development 

Corporation board member and Bay City 

Historic Commission

ML110840441

David Dunham STP 9 Matagorda County resident ML110840441

Owen Bludau STP 10 Director of Matagorda County Economic 

Development Corporation ML110840441

Kesha Rogers STP 11 Congressional candidate for 22nd 

Congressional District ML110840441

James Lovett STP 12 ML110840441

D. C. Dunham STP 13 Bay City Community Development 

Corporation ML110840441

Willie Rollins STP 14 Matagorda County resident ML110840441

Ian Overton STP 15 LaRouche PAC organizer ML110840441

John Corder STP 16 Brazoria County resident ML110840433

Judge Nate McDonald STP 17 Matagorda County judge ML110840433

Mitch Thames STP 18 Chamber of Commerce, emergency 

response public information officer ML110840433

Tim Powell STP 19 STP Vice President ML110840433

Ken Head STP 20 ML110840433

Mike Bolin STP 21 ML110840433

John Corder STP 22 Brazoria County resident ML110840433

Casey Kile STP 23 Bay City Babe Ruth (local sport 

organization) ML110840433

Robert Singleton STP 24 Austin resident ML110840433

Karen Hadden STP 25 Executive director of SEED Coalition ML110840433

Bobby Head STP 26 Matagorda County resident ML110840433

Tom Kovar STP 27 Bay City resident ML110840433

Vicki Adams STP 28 Superintendent Palacios ISD ML110730188

Eva Esparza STP 29 Austin resident ML110960078

Darby Riley STP 30 San Antonio resident ML110960079

Kamala Platt STP 31 ML110960080

Marion Mlotok STP 32 Austin resident ML110960081

Karen Seal STP 33 Lacoste resident ML110960082
Appendix A

A-3 

Commenter Commenter ID Affiliation (if stated) ADAMS No.

Kassandra Levay STP 34 San Antonio resident ML110960083

Unknown STP 35 ML110960084

T. Burns STP 36 Midland resident ML110960086

Jolly Clark STP 37 ML110960087

Dale Bulla STP 38 ML110960088

William Stout STP 39 ML110960089

C. J. Keudell STP 40 Austin resident ML110960090

Tarek Tonsson STP 41 ML110960091

Carol Geiger STP 42 ML110960092

Veryan and Greg Thompson STP 43 ML110960093

Robert Singleton STP 44 ML110960094

Karen Hadden STP 45 SEED Coalition ML110960095

Alan Apurim STP 46 ML110960096

Brandi Clark Burton STP 47 Austin resident ML110960097

Carol Geiger STP 48 Austin resident ML110960098

Eric Lane STP 49 San Antonio resident ML110960099

Jenna Findley STP 50 ML111010476

Margaret Reed STP 51 Austin resident ML111010477

Scott and Cyndy Reynolds STP 52 ML111010478

Jennifer Meador STP 53 Austin resident ML111010604

Joy Malacara STP 54 Austin resident ML111010479

Melanie and David Winters STP 55 ML111010506

J. R. Rhode STP 56 ML111010507

Christine Fry STP 57 ML111010508

Leona Slodge STP 58 Austin resident ML111010509

Carolyn Campbell STP 59 Austin resident ML111010510

Bryan Dunlap and Todd 

Rinehart STP 60 ML111010517

Peggy Cravens STP 61 Austin resident ML111010518

Shannon Jurak STP 62 Austin resident ML111010519

Thomas Nelms STP 63 ML111010520

T. Nelms STP 64 ML111010521

Peggy Pryor STP 65 Andrews resident ML110960077

Edmund Kelley STP 66 Austin resident ML11105A023

Maria Hogan STP 67 ML11105A020
Appendix A

A-4 

Commenter Commenter ID Affiliation (if stated) ADAMS No.

Randy Weber

STP 1 (letter, 

also captured in 

public meeting 

transcript) 

Texas State Representative ML11108A059

Beth Larsen STP 68 Austin resident ML11119A007

Dzan Nguyen STP 69 Austin resident ML11119A008

John Trimble STP 70 Austin resident ML11119A010

Aguilar family STP 71 ML11119A011

Juan Aguilar STP 72 ML11119A012

Douglas McArthur STP 73 Austin resident ML11119A013

Shawn Tracy STP 74 ML11119A014

Kelly Simon STP 75 Austin resident ML11119A015

N/A STP 76 ML11119A016

Judy Moore STP 77 ML11119A017

Cynthia Gebhardt STP 78 ML11119A018

Rory Holcomb STP 79 Austin resident ML11119A019

N/A STP 80 ML11119A020

1 Comments received during the scoping comment period applicable to this environmental review 

2 are presented in this section along with the NRC response. The comments that are general or 

3 outside the scope of the environmental review for South Texas Project (STP) license renewal 

4 are not included here but can be found in the Scoping Summary Report (ADAMS 

5 No. ML11153A082). To maintain consistency with the Scoping Summary Report, the unique 

6 identifier used in that report for each set of comments is retained in this Appendix A.

7 Applicable scoping comments are grouped in the following categories and presented in the 

8 following order: 

9 • alternatives to license renewal of STP, 

10 • socioeconomic impact of STP, 

11 • water usage, 

12 • human health,

13 • postulated accidents, 

14 • terrestrial or aquatic ecology, and 

15 • uranium fuel cycle and waste management. 

16 A.1.1 Alternatives to License Renewal of STP, Units 1 and 2

17 The original sources for the comments in this category (alternatives to license renewal) can be 

18 found at the back of the Scoping Summary Report and are labeled with the following identifiers: 

19 12-2, 15-1, 24-3, 25-5, 26-2, 27-2, 27-4, 29-2, 30-1, 31-2, 32-3, 35-2, 36-6, 38-2, 39-3, 40-2, 

20 43-3, 45-3, 46-3, 47-4, 49-2, 51-2, 52-2, 53-2, 54-3, 55-2, 57-2, 59-2, 60-3, 61 2, 62-2, 69-2, 

21 73-2, 74-1, 77-2, 79-2, and 80-2. These comments are extracted from the original sources.
Appendix A

A-5 

Comment 12-2

8 Yes, the natural gas plant is better than the coal plant, and I’m not particularly in favor of a coal 

9 plant in Matagorda County, but natural gas is contributing to global warming, and we cannot 

10 afford to build any more of it than we have to.

1 : Several nations have nuclear energy policies. These policies are all variations 

2 on one theme: one, oil is not a dependable source of energy, it can be interrupted at any time 

3 and it is not feasible to store more than a few months worth of reserve supply; two, nuclear 

4 energy is the only source of energy, other than wind and solar—which I hope come along in the 

5 future but at the present have to be considered in the development stage—nuclear energy is the 

6 only source of energy that can produce large quantities of energy without dumping large 

7 quantities of carbon dioxide into the atmosphere.

11 I’m a strong supporter of nuclear energy; I’m a strong supporter of renewing these. In due 

12 course, I will be a strong supporter of Units 3 and 4. Thank you.

Comment 15-1

18 When you start going into other examples of energy, such as wind or solar, the amount of return 

19 gets even worse because the amount of radiant heat coming down from the sun is only about 

20 200 watts per square meter, and the amount of land area and the cost of building and 

21 maintaining solar panels or windmills is far, far greater than the actual benefit you get from 

22 them, not to mention that windmills kill birds by the dozen and solar panels, with their polarized 

23 lights, kill insects by the countless numbers.

13 : And, I think that it’s probably best, when talking about the environmental 

14 benefits of nuclear power, to compare it with the environmental problems that other forms of 

15 power offer. So for example, the amount of energy in one pellet of uranium, about the size of 

16 my fingernail here, is equivalent in energy to about 30 barrels of oil or 6.15 tons of coal, or 

23 1 17 /2 tons of dry wood.

Comment 24-3

28 The other thing about switching forms of energy is that you can create jobs locally that are going 

29 to be exclusively locally. Nuclear power, a lot of the jobs that are generated are going to be 

30 foreign manufacturing jobs. The components for these plants are built off site; they don’t really 

31 generate that much for your local economy.

24 : Nuclear power was also always intended to be a bridge technology. We’re 

25 always going to find something better, and what we could do right now instead of re-license 

26 these is make an investment in renewables which could have, in terms of jobs, just as much of 

27 an impact as extending the life of this plant or building new units.

32 There are new and exciting technologies that we could be counting on. For example, there’s an 

33 Australian company called EnviroMission that’s just about to open a project in Arizona. What it 

34 is; it’s a tower, just a tower, covered around the base with thick plastic. What it does is it 

35 captures the heat of the sun; the heated air rises up a chimney and turns a turbine. It’s basically 

36 the only moving part, so the turbine and then the generators from it.

37 The cool thing about it is that it continues to generate electricity even at night because the hea[t]

38 of the ground continues to make this temperature differential, and the air continues up the 

39 chimney, and the turbines continue to turn.

40 This is the kind of thing that can be built and provide localized power. In West Texas, for 

41 example, we could build these things and not have to ship the power across the State. We 

42 could actually use it to provide energy where it’s built.

43 Comment 25-5: A big issue is need for power. Right now in the legal case involving Units 3 

44 and 4, the Atomic Safety and Licensing Board has agreed to hear a contention that is one of 

45 omission. There was a failure to analyze what alternatives were there in terms of looking at 

46 energy efficiency. Building codes in particular are going to be saving; they’ve been adopted, 
Appendix A

A-6 

1 going to be saving some 2,200 megawatts of power in Texas. We need to look at whether the 

2 power is needed and then we need to look at how else it could be generated.

3 And, certainly[,] jobs are crucially important in every community. We realize that that’s 

4 important here. I think it’s time to look at what are the options in terms of transition, what other 

5 kinds of ways to generate electricity could occur here; I think there are many and to start looking 

6 at training and what other options exist.

Comment 26-2

13 Would I like to see all of our power generated totally clean[?] Yes, I would. It’s not realistic, not 

14 with what we have as today’s knowledge.

7 : Randy Weber was here last week. He’s our State representative. He got over 

8 in the next room and he said that Texas is growing by 113,000 people a month. Wow. We’re 

9 outgrowing all the states combined. We’re getting more people into Texas. He says if we keep 

10 growing the way we are, that by 2015 we’re going to have to have five new nuclear plants, or 

11 16 coal plants, or 28 gas plants, or 3,000 windmills if the windmills agree to turn 24-7-365. You 

12 know that’s not going to happen.

15 Comment 27-2: You have to have electricity and you have to have a lot of it. I wish I could 

16 afford Austin’s 16 percent. But, you have to have a lot of electricity nowadays because of the 

17 way the population is, and if you look at the last 40-50 years of power generation, of gas-fired 

18 plants or coal-fired plants and how hazardous they are to the environment and people, then I 

19 think you [cannot] help but realize how safe nuclear power is. The Government has been using 

20 it to power their vehicles in the military for a long time.

21 Comment 29-2: There are safer alternative technologies that can replace the energy generated 

22 by these reactors.

23 Comment 30-1: Well before 2027, we should have outgrown the need for nuclear power with 

24 clean alternative energy and conservation [and] efficiency ...

25 Comment 31-2: I urge the denial of the relicensing of the STP. As a San Antonio resident, I 

26 value my community and know that we are committed to renewables and conservation, much 

27 better paths to the future on a sustainable planet.

28 Comment 32-3: We should be investing in solar and wind and dismantling our aging reactors.

29 Comment 35-2: There are cheaper and renewable ways to get our power, and I would love to 

30 see Texas lead the way in these fields. Not continue to lead us down a dead end road with 

31 nuclear power.

32 Comment 36-6: STP does not displace [carbon dioxide] emissions. Other, truly renewable 

33 energy sources are much more highly developed now and can replace STP. By scheduled 

34 renewal, nuclear energy will be totally unnecessary.

35 Comment 38-2: We need to move toward heavy development of solar and wind regardless of 

36 the cost[—]they would be so much safer (and most likely cheaper in the long run, considering

37 [(lacking of or merit of)] all the waste and other negatives of solar).

38 Comment 39-3: Safer, cleaner alternative ways to generate the same power (in essence[,] to 

39 boil water) exist today and should be used and funded, just like the Nuclear and Petroleum 

40 industries have been subsidized by the U.S. Government to the tune of BILLIONS of dollars 

41 annually.

42 Comment 40-2: At this point in time, I feel that the U.S. should move away from nuclear and oil 

43 as primary energy sources. Let’s develop more renewable options.
Appendix A

A-7 

1 Comment 43-3: Here in Texas, we have a wonderful abundance of sun as well as wind, neither 

2 depend[e]nt on other countries. We should be making use of these natural resources[,] which 

3 are safer, reduce use of scarce water, and [cannot] be used as political weapons.

4 Comment 45-3: Safer, cleaner alternative ways to generate the same power exist today and 

5 should be used. We should not be subjected to worrying about radioactive contamination—just 

6 to generate electricity. We should not have to worry about terrorists attacking a radioactive 

7 energy generation source, and we don’t have these worries with solar, geothermal, natural gas, 

8 or wind power. These forms of energy generation, combined with energy efficiency and 

9 ever-improving methods of storage, could easily replace the electricity generated by Units 1 

10 [and] 2. When these units have been down due to problems or fuel replacement, it did not 

11 cause problems with the grid or lead to blackouts. We can replace the generation of these units 

12 with safer, cleaner technologies.

13 Comment 46-3: For alternative energy sources, and a way to get the USA off foreign oil 

14 dependence that is costing us both in trade balance and military costs, see the downloadable 

15 document describing achievable ecological solutions for all these needs:

16 http://phoenixprojectfoundation.us/uploads/USA Article V SHE Document.pdf

17 Thank you for your hard work and consideration of these issues. Please be sure to keep me 

18 informed as this regulatory process proceeds.

19 Comment 47-4: We have safer and cleaner ways to generate the same power—THAT is where 

20 our money and attention need to be directed.

21 Comment 49-2: There are safer, cleaner alternatives to generate the same power that exists 

22 today, and we should commit the country to use them.

23 Comment 51-2: Safer, cleaner alternative ways to generate the same power exist today and 

24 should be used. Studies have found that energy efficiency and renewable energy sources, 

25 which are abundant in Texas, could replace the power generated by these two old nuclear 

26 reactors.

27 Comment 52-2: NOW is the time to make a commitment to safer and renewable energy 

28 sources.

29 Comment 53-2: Safer, cleaner alternative ways to generate the same power exist today and 

30 should be used. Studies have found that energy efficiency and renewable energy sources, 

31 which are abundant in Texas, could replace the power generated by these two old nuclear 

32 reactors.

33 Comment 54-3: There are safer, cleaner alternative ways to generate the same power available 

34 today, and these should be used instead of nuclear energy.

35 Comment 55-2: Safer, cleaner alternative ways to generate the same power exist today and 

36 should be used. Studies have found that energy efficiency and renewable energy sources, 

37 which are abundant in Texas, could replace the power generated by these two old nuclear 

38 reactors.

39 Comment 57-2: I believe there are alternative ways to generate power and support a more 

40 ...[uncertain handwriting].

41 Comment 59-2: There are safer, cleaner alternative ways to generate power!

42 Comment 60-3: Texas is ready for a new way to power our lives; give Texa[s] a chance for a 

43 cleaner, safer power of energy ...
Appendix A

A-8 

1 Comment 61-2: There are safer, cleaner alternative ways to generate the same power that 

2 exist today and should be used. 

3 Comment 62-2: Safer, cleaner alternative ways to generate the same power exist today and 

4 should be used. 

5 Comment 69-2: Safer, cleaner alternative ways to generate the same power exist today and 

6 should be used.

Comment 73-2

9 While many promises are made as to the safety of nuclear power, recent history demands we 

10 not place too much reliance on them. Some things do not readily lend themselves to 

11 engineering solutions. I believe nuclear power is one of those things, and thus I am opposed to 

12 the requested re-licensing.

7 : Rather than pushing for more water-consuming nuclear power plants, Texas 

8 needs to focus more on the development of renewable energy sources such as wind and solar.

13 Comment 74-1: To ensure the safety of my family and other Texas families, I believe the 

14 re-licensing of these two reactors for an additional [20] years should be halted for safety 

15 reasons. There are safer and cleaner alternatives than outdated reactors. These alternatives 

16 (solar, wind, etc.) should be strongly considered.

17 Comment 77-2: There are safer and cleaner ways to generate power today that we need to 

18 support and use. Renewable energy sources are everywhere in Texas and could replace more 

19 dangerous sources if funded and supported. Another factor to think about is the huge amount 

20 of water used in the reactors. The water from the Colorado River is needed to farming, cattle 

21 and families. Are we not just creating another problem by using energy sources that use so 

22 much water?

23 Comment 79-2: Safer, cleaner alternative ways to generate the same power exist today and 

24 should be used. Studies have found that energy efficiency and renewable energy sources, 

25 which are abundant in Texas, could replace the power generated by these two old nuclear 

26 reactors.

Comment 80-2

30 Response: These comments provide input (or data) for the staff’s environmental analysis of 

31 the alternatives to license renewal, including the alternative of not renewing the operating 

32 license—also known as the “no-action” alternative. In Chapter 8 of this supplemental 

33 environmental impact statement (SEIS), the staff evaluated the alternatives to license renewal. 

34 These include new nuclear generation, natural-gas-fired combined-cycle generation, 

35 supercritical coal-fired generation, combination alternative, and purchased power. In addition, in 

36 Chapter 8 of this SEIS, the staff considered many other options that were subsequently 

37 dismissed for reasons of technical, resource availability, or commercial limitations. These 

38 include offsite nuclear, gas and coal-fired capacity; energy conservation and energy efficiency; 

39 wind power; solar power; hydroelectric power; wave and ocean energy; geothermal power; 

40 municipal solid waste; biomass; biofuels; oil-fired power; fuel cells; and delayed retirement.

27 : Safer, cleaner alternative ways to generate the same power exist today and 

28 should be used. Studies have found that energy efficiency and renewable sources, which are 

29 abundant in Texas, could replace the power generated by these two old nuclear reactors.

41 A.1.2 Socioeconomic Impact of STP, Units 1 and 2

42 The original sources for the comments in this category (socioeconomic) can be found at the 

43 back of the Scoping Summary Report and are labeled with the following identifiers: 1-2, 3-1, 

44 5-2, 6-2, 8-1, 9-1, 10-1, 13-1, 14-1, 20-2, 23-1, and 24-1. These comments are extracted from 

45 the original sources.
Appendix A

A-9 

Comment 1-2

5 For over 20 years, [the] existing [STP] units have supplied safe, clean and reliable energy to 

6 more than 2 million Texas homes while also providing permanent, well-paying jobs. The facility 

7 is a recognized industry leader in production, reliability and safety, as well as being focused and 

8 committed to the safety of its employees and the surrounding communities.

1 : STP is the largest employer in Matagorda County with more than 

2 1,200 employees and for 30 years has been a key part of the county and local communities. 

3 The company’s employees are active in the local community, serving on school boards, 

4 chambers and in civic and service organizations.

Comment 3-1

14 In 2008, STP started its educational incentive program as part of its workforce development 

15 efforts. It represents a $4.2 million investment that provides great opportunities for well-paying 

16 jobs in this community. For over 20 years, the facility has produced safe, reliable energy to the 

17 citizens of Texas, and for the past [7] consecutive years, STP has produced more electricity 

18 than any other two-unit nuclear plant in the country.

9 : With that being stated, STP makes it obvious. STP is the largest employer to 

10 the county, their employees stay active in numerous organizations, and many serve as elected 

11 officials. They have a very high importance to safety as well as the environment. Their 

12 employees set the standard for their industry. Just last October, STP was named one of 

13 America’s safest companies, the first nuclear facility to ever be honored with that award.

19 The license extension of STP will continue to provide jobs and economic benefits to our local 

20 community. 

21 Comment 5-2: Our employees try to contribute and try to continue to do what they can to 

22 improve life within this community by serving, as the judge said, on various boards and 

23 providing leadership positions, and we’re thankful that you give us that opportunity.

Comment 6-2

27 The culture of continuing improvement for all aspects of power generation overflows in the 

28 community. STP[NOC]’s contributions to our local charities, our chambers of commerce and 

29 civic groups provide the commitment to our future and our joint success. They give both time 

30 and money to make sure Matagorda County is the best in all of Texas.

24 : During the record low temperatures when there were problems in Texas with 

25 other sources of power, our local plant didn’t have any problems keeping the power generating 

26 for Texans.

Comment 8-1

34 STP contributed $100,000 to the Center for Energy Development and currently provides staffing 

35 to train our community’s young adults. STP employees have been strong leaders in our 

36 strategic planning for the future of this community with our Bay City Matagorda United Plan. 

37 STP employees have also invested in the renovation of our historic downtown district and its 

38 beautification efforts. I have also served with STP employees on various community boards 

39 and have witnessed firsthand their dedication, their desire to be good neighbors, and their 

40 commitment to our community.

31 : My name is Cheryl Stewart, and I’m on the Bay City Community Development 

32 Corporation Board and also the Historic Commission, and I’m here today to inform you of the 

33 many ways that I have personally seen STP impact our community in a positive way.

41 I am sure that our community would experience a huge loss without the involvement and 

42 support of STP. 

43 Comment 9-1: The importance of STP to that future [cannot] be overemphasized. My employer 

44 is an educational partner with STP and their contribution to the future of our community through 

45 support of education is unprecedented in my 20 years of higher education experience.
Appendix A

A-10

1 Comment 10-1: STP personifies the best type of economic development project that a 

2 community could want. It’s created a large number of jobs that have been filled with highly 

3 educated and highly skilled workers. It pays wages far above the county average. It’s greatly 

4 enhanced the tax base of Matagorda County and to the taxing entities in whose location it is 

5 situation. It makes significant annual financial contributions to civic, educational, and 

6 promotional programs benefitting all of the county. It has created and funded a major 

7 grow-your-own technical education program, providing good career opportunities for all of our 

8 local youth. Its employee and their families are extensively involved in all aspects of our 

9 community and political life, and, by so doing, they make Matagorda County a much better 

10 place in which to live for all the rest of us.

Comment 13-1

16 And, of course, we love to show off our assets, and I’m proud to say that every time I meet 

17 someone I always talk about we’re the home of a nuclear power plant, because I’m just really 

18 proud of that. And, because of that, I’ve also invited all of our surrounding economic 

19 development associates to come and visit STP because I want them to see the high level of 

20 security and safety that they operate in every day. And, I’ve got them actually scheduled next 

21 month, so Mr. Halpin, hopefully you can stop by and say hello.

11 : And have you ever wondered what Bay City and Matagorda County would be 

12 like if we didn’t have South Texas Nuclear Operating Company [STPNOC] here? There isn’t a 

13 day that goes by that we don’t run into or communicate with STP employees. They’re involved 

14 throughout our community, and I really have a hard time imagining what it would be like here 

15 without them because they’re such a huge asset to our community.

22 But, as an economic developer and resident of Matagorda County, I’m very thankful to have 

23 such a great asset in our community, and they will not only have a positive impact but an 

24 excellent impact on our taxes, community development, and our environmental justice. 

Comment 14-1

28 Matagorda County, like many rural communities, over the years has suffered from brain drain, 

29 where your best and your brightest tend to leave and seek their fortunes other places. Well, 

30 STP has helped to reverse that trend in Matagorda County. Not only does it provide great 

31 paying jobs for our youth that even go off to college and return to become productive citizens in 

32 this community, they have reduced the amount of exodus of kids leaving this community in the 

33 first place with the creation of the Center for Energy Development where we can now grow our 

34 own.

25 : I don’t have a lot of knowledge on technical skills about nuclear energy, so I’m 

26 just going to limit my comments to the social environmental impact that STP has had on this 

27 community.

35 The social environmental impact of that, just in and of itself, has been tremendous. If we were 

36 to track the intellectual scale of Matagorda County within the last 20 years, you can begin to see 

37 that if you start off with the census of 2000, the number of high school graduated individuals in 

38 Matagorda County represented about one-third, another group of individuals that did not have a 

39 high school diploma represented another third. So effectively, basically, two-thirds of the 

40 population of Matagorda County had a high school diploma or less.

41 If you begin to look at the recent trend since the [STP] has been in this community, you can see 

42 that trend reversing and the numbers of educated citizens of this community going up.

43 When I returned to Matagorda County several years ago, I became actively involved in a lot of 

44 the nonprofit organizations. The premier nonprofit organization for this community was United 

45 Way, but at that time, unfortunately, United Way was under poor leadership and dysfunctional.
Appendix A

A-11

1 Thanks to the leadership of two employees from STP, one by the name of Gerald Wilson, 

2 another by the name of Chris Johnson, who took the leadership of the United Way and made it 

3 the organization that it is today that’s supporting over 30 other non-profit organizations in this 

4 community, there are others that could talk more eloquently about the economic impact of STP, 

5 but the ancillary benefit of its employees serving on nonprofit boards, and not to mention our 

6 faith-based communities through their tithes, their offerings that support churches and other 

7 community-based organizations, that contribution is almost immeasurable.

8 Comment 20-2: What should you focus on? Obviously, our environmental concerns are a huge 

9 part of this. I’m [with] the Convention and Visitors Bureau, and one of our main focuses is 

10 bringing tourists down to Matagorda County to see what we have to offer.

Comment 23-1

16 On the economic standpoint, Mr. Head said earlier last year we hosted a regional tournament. 

17 We had five states come to visit Bay City, over 400 visitors in town, over 100,000 new dollars 

18 just last year, and without STP supporting that, we wouldn’t have been able to host that 

19 tournament. So, we’d like to thank them. 

11 : And I’d just like to say that, on behalf of Babe Ruth, we’re very grateful for 

12 everything STP does for us as an organization. They’re a major sponsor in all of our events. 

13 Over the last [10] years, we’ve hosted [4] regional tournaments and [11] or [12] state 

14 tournaments, and without STP[NOC]’s support, we would never have been able to participate in 

15 those tournaments or even host those tournaments. 

20 Not only do they help us monetarily with our tournaments, but their employees also volunteer 

21 with us, and we’d like to thank them for their employees and letting them volunteer. 

22 Over the last [10] years, like I said, we’ve hosted about 15 tournaments and probably half a

23 million new dollars in Matagorda County over the last [10] years.

Comment 24-1

28 But, Austin’s experience with [Units] 1 and 2 was a nightmare. We had it thrust upon us by 

29 politicians who were determined to continue to take public votes until we bought a share of the 

30 plant. We tried to get out of the plant at one point, tried to sell our 16 percent share, and 

31 [cannot]. 

24 : You may ask why I’d want to come down from Austin to talk to you. Well, 

25 Austin is a 16 percent partner in [Units 1 and 2], and if you look back over the history of the 

26 project, we’ve got a lot less reason to celebrate this plant than may be some people who live 

27 here do. I’m not going to talk a lot about jobs, but I’m going to wrap up with that tonight. 

32 The problem was at its worst in the ’90s when 42 cents out of every dollar that we paid on a 

33 utility bill was going for debt service at NRG. For our 16 percent share, we were paying almost 

34 half of our utility bill for debt service on the project.

35 Response: These comments provided input (or data) for the staff’s environmental analysis of 

36 the socioeconomic impacts of STP on local and regional communities. The comments include 

37 socioeconomic-related items such as taxes, employment, education, tourism, and public and 

38 civic services. 

39 The socioeconomic impacts of renewing the STP operating license and alternatives to license 

40 renewal are discussed in Sections 2.2.9, 4.9, 8.1.8, 8.2.8, 8.3.8, 8.4.8, 8.5.8, and 8.7.8 of this 

41 SEIS.

42 A.1.3 Water Usage

43 The original sources for the comments in this category (water usage) can be found at the back 

44 of the Scoping Summary Report and are labeled with the following identifiers: 25-4, 29-3, 32-2, 
Appendix A

A-12

1 36-5, 37-3, 39-4, 40-3, 41-2, 45-4, 47-2, 51-3, 53-3, 54-2, 55-3, 59-3, 60-2, 62-4, 63-2, 64-3, 

2 67-2, 71-2, 75-2, 77-2, and 80-4. These comments are extracted from the original sources.

Comment 25-4

7 Water use is an increasing issue. Up until this point, the highest use that I know of through 

8 researchers looking at this is 49 percent of the Colorado River has been used for cooling 

9 purposes, and I know a couple of summers ago there was a lot of pumping going on to refill the 

10 reservoir when it got kind of low. 

3 : There is a problem with the leaking main cooling reservoir [MCR], which was 

4 described and documented in the license application for Units 3 and 4. There needs to be 

5 tracking of where the water is going. Is it reaching the Gulf, where is it going, what is it doing? 

6 That should be part of the re-licensing study and analysis.

11 It’s a problem for those of us in Austin. The Colorado River water has to serve a lot of 

12 purposes. Rice farmers need it; we’re going to need it for many, many purposes, recreation, 

13 fishing on our end. And, Lake Travis levels were at an all-time low several years ago. Every 

14 single dam on the whole lake was closed; you couldn’t put a boat in.

15 And, we would like to see something shift to where this much water was no longer required. 

16 Certainly, you’re still going to have to still cool spent fuel rods and so on and so forth, but it is a 

17 question when you look at continuing the reactors’ life.

18 Comment 29-3: Vast water consumption requirements for these reactors add a hidden cost to 

19 taxpayers, farmers, ranchers and other industries. As water becomes more scarce in Texas, 

20 this becomes a very high risk should there be a meltdown like Japan.

21 Comment 32-2: We have been suffering for many years from drought conditions here in Texas. 

22 Given the huge amount of water needed for normal operation and to avert nuclear catastrophe, 

23 we would be better served to use the little water we have for agriculture and residential use.

24 Comment 36-5: STP requires a large amount of cooling water to operate, critical, as seen in 

25 Japan. Texas is facing more and more serious water shortages, as population rises and global 

26 warming effects take place. The need for water for other purposes than STP will grow. STP 

27 should relinquish its water use and shut down.

28 Comment 37-3: Vast consumption of water use, largely Colorado River water, which is 

29 increasingly needed for drinking water, livestock, and farming. The [MCR] is leaking out the 

30 bottom. How and when will this be repaired? Climate change—rising temperatures could affect 

31 whether there is enough cool water to cool the reactors.

32 Comment 39-4: Vast consumption of water use, largely Colorado River water, which is 

33 increasingly needed for drinking water, livestock, and farming in an era of more frequent and 

34 lengthy periods of drought. The [MCR] is leaking out of the bottom: How and when will this be 

35 repaired? Climate change considerations: The rising atmospheric temperatures could affect 

36 whether there is enough cool water to cool the reactors.

37 Comment 40-3: Also, as you know, nuclear power supplies require a lot of water for cooling 

38 purposes. Once again, the State of Texas is experienced drought in 98 [percent] of its counties. 

39 Let’s save the water for agricultural purposes.

40 Comment 41-2: The reactors consume vast quantities of water; use largely from the Colorado 

41 River; water that is needed for drinking water.

42 Comment 45-4: These reactors consume vast quantities of water use, largely Colorado River 

43 water, which is increasingly needed for drinking water, livestock, and farming. Drought is 

44 expected to increase in our region. We are concerned that there will not be adequate water to 

45 cool the reactors in an emergency or that the water will not be cool enough to effectively cool 
Appendix A

A-13

1 the reactors. Some U.S. reactors have had to shut down due to high water temperatures, and 

2 this could [result in a] scenario [that] could worsen with climate change impacts, leaving us with 

3 a dangerous situation and a shortage of power during intense heat waves. 

4 The [MCR] is leaking out the bottom, as documented in the license application for STP 3 [and] 

5 4. The reactors should not be relicensed when this serious condition remains unresolved. How 

6 and when will this be repaired? What studies have been done by the NRC on this serious 

7 problem? How can relicensing even be considered until this situation is corrected? Where is 

8 the water going, and how extensive is the radioactivity that may be leaking into the Gulf of 

9 Mexico [or the] Colorado River [or both]? 

10 Comment 47-2: We have limited access to freshwater that can be used for this facility. The 

11 priority should be for drinking water, livestock, and farming. I understand that the [MCR] is 

12 leaking out the bottom. How and when will this be repaired?

13 Comment 51-3: These reactors consume vast quantities of water use, largely from the 

14 Colorado River, water that is needed for drinking water, livestock, and farming.

15 Comment 53-3: These reactors consume vast quantities of water use, largely from the 

16 Colorado River, water that is needed for drinking water, livestock, and farming.

17 Comment 54-2: The reactors would affect the Austin area by consuming vast quantities of our 

18 drinking water from the Colorado River ...

19 Comment 55-3... these reactors consume vast quantities of water use, largely from the 

20 Colorado River, water that is needed for drinking water, livestock and farming;

21 Comment 59-3: Leave the Colorado River for other purposes—drinking, livestock, and farming.

22 Comment 60-2: Please help protect Americans, Texans, and all human beings that come into 

23 contact with the Texas Colorado River from having it depleted by renewing these reactors 

24 licenses[,] to continue consuming vast quantities. Protect the waterways from being poisoned in 

25 the event of emergencies at nuclear plants.

26 Comment 62-4: These reactors consume large quantities of water use, largely from the 

27 Colorado River, water that is needed for drinking water, livestock, and farming.

28 Comment 63-2: Too much water is used to cool the reactors! Too much water is used. It’s 

29 dangerous.

30 Comment 64-3: Too much water is wasted! There goes the drinking water; all gone and toxic! 

31 Please do not relicense these two reactors.

32 Comment 67-2: The vast amount of water taken up by these reactors is very much needed for 

33 other purposes.

34 Comment 71-2: Nuclear reactors use large quantities of water, water that could be used for 

35 drinking, livestock, and farming.

36 Comment 75-2: These reactors consume vast quantities of water use, largely from the 

37 Colorado River[;] water that is needed for drinking water, livestock[,] and farming.

38 Comment 77-2: There are safer and cleaner ways to generate power today that we need to 

39 support and use. Renewable energy sources are everywhere in Texas and could replace more 

40 dangerous sources if funded and supported. Another factor to think about is the huge amount 

41 of water used in the reactors. The water from the Colorado River is needed [for] farming, 

42 cattle[,] and families. Are we not just creating another problem by using energy sources that 

43 use so much water?
Appendix A

A-14

Comment 80-4

3 Response: These comments provided input (or data) for the staff’s environmental analysis of 

4 water resource impacts of STP on local and regional communities. These comments raise 

5 concerns about the water usage from the Colorado River and leakage from the MCR. The staff 

6 discusses water usage impacts in Sections 2.2.4, 2.2.5, 4.3, 4.4, 8.1.2, 8.1.3, 8.2.2, 8.2.3, 8.3.2, 

7 8.3.3, 8.4.2, 8.4.3, 8.5.2, 8.7.2, and 8.7.3 of this SEIS. 

1 : These reactors consume vast quantities of water use, largely from the 

2 Colorado River[;] water that is needed for drinking water, livestock, and farming.

8 A.1.4 Human Health 

9 The original sources for the comments in this category (human health or Radiation Impact) can 

10 be found at the back of the Scoping Summary Report and are labeled with the following 

11 identifiers: 25-1, 29-4, 36-3, and 45-6. These comments are extracted from the original 

12 sources.

13 Comment 25-1: I also have concerns about the re-licensing of reactors 1 and 2. I think there 

14 are a number of issues that need to be looked at carefully during this process and bearing 

15 worker safety in mind. One of them is tritium, and basically, there has been tritium showing up 

16 in wells on the site. This needs to be looked into thoroughly, as well as tritium in the Colorado 

17 River, and documented, measured, carefully analyzed to see if it’s safe to continue down this 

18 path at this point in time.

19 Comment 29-4: There is currently a leak in the bottom. What are the health implications to 

20 wildlife and people of this leak? When will it be fixed? They have not repaired this, how can they 

21 be trusted for another 20 years? 

22 Comment 36-3: I have heard the news reports that the leakage of plutonium and cesium is not 

23 a cause for concern. As a physician interested in this area, I know that this is ridiculous. I 

24 remember how much polonium [alpha emitter] was required to assassinate a Russian person in 

25 the UK. 

Comment 45-6

30 Response: These comments provided input (or data) for the staff’s environmental analysis of 

31 human health and environmental impacts related to possible radioactive leaks from STP.

26 : We are concerned about increasing tritium levels in wells [on site] and in the 

27 Colorado River. Extensive testing should occur for all organisms in the region, and exposure of 

28 whooping cranes to tritium and other radionuclides should be examined since they are an 

29 endangered species and their winter grounds are only 35 miles from the STP site.

32 To ensure that STP is operated safely, the NRC licenses the plant to operate, licenses the plant 

33 operators, and establishes license conditions for the safe operation. The NRC provides 

34 continuous oversight of STP through its reactor oversight process (ROP) to verify that 

35 operations are in accordance with NRC regulations. The NRC has full authority to take 

36 necessary actions to protect public health and safety and the environment, and it may demand 

37 immediate STPNOC actions, up to and including a plant shutdown.

38 Radiation doses to members of the public from the current operations of STP are evaluated in 

39 the SEIS in Section 4.8.2. In that section, the staff reviewed the radioactive releases from STP 

40 (i.e., radioactive gaseous and liquid effluents, radiation from radioactive waste storage buildings, 

41 radiological impacts from refueling and maintenance activities, and tritium leaks) and the results 

42 of STPNOC’s radiological environmental monitoring program (REMP) (i.e., analysis of air, water 

43 (surface, ground, and drinking), sediment, vegetation, and aquatic and terrestrial biota for 

44 radioactivity). Based on its review, the staff concluded that the radiological impacts to members 

45 of the public were within NRC’s and U.S. Environmental Protection Agency’s (EPA’s) dose
Appendix A

A-15

1 standards, and there were no radiological effects to the environment and non-human species 

2 (i.e., local biota) from plant operation. 

3 The staff also evaluated the STP REMP. The REMP quantifies the environmental impacts 

4 associated with radioactive releases from the plant. The REMP monitors the environment over 

5 time, starting before the plant operates to establish background radiation levels and throughout 

6 its operating lifetime to monitor radioactivity in the local environment. The REMP provides a 

7 mechanism for determining the levels of radioactivity in the environment to ensure that any 

8 accumulation of radionuclides released into the environment will not become significant as a 

9 result of plant operations. Based on the review of several years of data, the staff concluded that 

10 there were no measurable impacts to the environment as a result of radioactive releases from 

11 STP.

12 In summary, the NRC provides continuous oversight of STP through its ROP to verify that they 

13 are being operated in accordance with NRC regulations. STP is required to maintain its 

14 radioactive effluent release program in compliance with NRC regulations and consistent with 

15 EPA standards. The NRC will continue to inspect STPNOC’s compliance with radioactive 

16 effluent. 

17 A.1.5 Postulated Accidents

18 The original sources for the comments in this category can be found at the back of the Scoping 

19 Summary Report and are labeled with the following identifiers: 25-3, 37-2, 39-2, 42-1, 45-2, and 

20 48-1. These comments are extracted from the original sources.

21 Comment 25-3: [I]n 1982, there was a study done for the [NRC] called the [CRAC 2] Study. It 

22 found that if there were an accident—and they were looking at Units 1 and 2—that there would 

23 be 18,000 early deaths. They would also be followed by thousands of cancers. That study has 

24 not been updated. The population in some of this region has grown, and it needs to be looked 

25 at again to find out what is the reality of the situation today, and that needs to be compared to 

26 other ways of generating electricity.

27 Comment 37-2: Risks of an accident, fires, or explosions at one or more reactors at the site, 

28 risks that could increase with aging reactors NRC’s 1982 CRAC 2 study found that there could 

29 be 18,000 early deaths if a serious accident occurred at the STP site.

30 Comment 39-2: Risks of an accident, fires, or explosions at one or more reactors at the site, 

31 risks that could increase with aging reactors. [NRC’s] 1982 CRAC 2 study found that there 

32 could be 18,000 early deaths if a serious accident occurred at the STP site.

33 Comment 42-1: The [license renewal application (LRA)] is inadequate because it: (a) fails to 

34 adequately address the applicant’s capacity to deal with fires and explosions that cause a loss 

35 of large areas of the plant—the mitigative strategies for addressing fires and explosions are 

36 inadequate to address the consequences of events such as the impacts of large commercial 

37 aircraft crashing into the reactors or related facilities, (b) fails to describe the means that would 

38 be used to determine radiation exposures to fire and explosion responders, and (c) fails to 

39 describe the means that would be used to protect fire and explosion responders from excessive 

40 radiation exposures.

41 Comment 45-2: We are all too aware of the fact that meltdowns can and do happen, and a 

42 recent Union of Concerned Scientists report notes that there were 14 near misses in the U.S. in 

43 2010. NRC’s 1982 CRAC 2 study found that there could be 18,000 early deaths if a serious 

44 accident occurred at the ST(N)P site, followed by thousands of cancers.
Appendix A

A-16

Comment 48-1

8 Response: These comments provided input (or data) on various aspects of severe accidents 

9 associated with fire and explosion hazards, ranging from the applicability of results from earlier 

10 NRC consequence studies (e.g., CRAC) to emergency management operation. The 

11 evaluations of STPNOC’s severe accident analysis are discussed in Section 5.2 of this SEIS. 

1 : The [LRA] is inadequate because it: (a) fails to adequately address the 

2 applicant’s capacity to deal with fires and explosions that cause a loss of large areas of the 

3 plant—the mitigative strategies for addressing fires and explosions are inadequate to address 

4 the consequences of events such as the impacts of large commercial aircraft crashing into the 

5 reactors or related facilities, (b) fails to describe the means that would be used to determine 

6 radiation exposures to fire and explosion responders, and (c) fails to describe the means that 

7 would be used to protect fire and explosion responders from excessive radiation exposures

12 The NRC and the global nuclear research and safety community have done extensive research 

13 over the past three decades evaluating reactor accidents and how they could affect the public. 

14 Earlier studies (e.g., NUREG/CR-2239, Technical Guidance for Siting Criteria Development, 

15 commonly referred to as the 1982 Siting Study or CRAC 2 Study) had uncertainties and 

16 conservatisms and did not include information on current plant design, operation, accident 

17 management strategies, emergency preparedness procedures, or post-9/11 enhancements to 

18 mitigative measures. Earlier work was also limited by both computer hardware and software 

19 available at that time. Researchers attempted to overcome these limitations by simplifying 

20 some estimates or assumptions concerning possible damage to the reactor core, the possible 

21 radioactive contamination that could be released, and possible failures of the reactor vessel and 

22 containment buildings. These efforts led to overestimates in the results, particularly in the 

23 1982 Siting Study (or CRAC 2 Study) report. This report was meant to assist the NRC staff in 

24 considering regulations for choosing nuclear power plant locations, but it has been regularly 

25 misinterpreted and misused as an estimate of accident consequences. Since those early 

26 studies, information from both NRC and cooperative foreign research has greatly increased our 

27 understanding of the timing and magnitude of possible radioactive releases from potential 

28 accidents at nuclear power plants. 

29 The NRC established a research project in 2006 to update its assessment of severe reactor 

30 accident scenarios and their potential consequences to human health. This research project, 

31 titled “State-of-the-Art Reactor Consequence Analyses (SOARCA),” was designed to develop 

32 best estimates of the public health effects that might result from a radiological release during a 

33 nuclear power plant accident. The SOARCA project used state-of-the-art computer codes to 

34 calculate accident progression and offsite consequences for important scenarios at two plants, 

35 Peach Bottom, a boiling-water reactor (BWR), and Surry, a pressurized-water reactor (PWR). 

36 These codes have been continuously updated to incorporate decades of experimental research. 

37 The SOARCA project had cooperation from the licensees of these plants to model them in great 

38 detail as they exist in their current state and include operator action timelines based on 

39 plant-specific procedures. The project also modeled the use of additional equipment and 

40 strategies required by the NRC following the terrorist attacks of September 11, 2001, to further 

41 improve each plant’s capability to mitigate events involving a loss of large areas of the plant 

42 caused by fire and explosions. 

43 SOARCA results show that when operators are successful in using available onsite equipment 

44 during the accidents analyzed in SOARCA, they can either (a) prevent the reactor from melting 

45 or (b) delay or reduce releases of radioactive material to the environment. Even if operators are 

46 unsuccessful in stopping the accident, SOARCA shows that the accidents progress more slowly 

47 and release much smaller amounts of radioactive material than calculated in the 1982 Siting 

48 Study or CRAC 2 Study. Therefore, public health consequences from severe nuclear reactor 

49 accident scenarios are smaller than previously calculated. The delayed releases calculated 
Appendix A

A-17

1 provide more time for emergency response actions, such as evacuating or sheltering. All 

2 modeled scenarios in SOARCA showed essentially zero early fatalities. In contrast, the 

3 1982 Siting Study calculated 92 mean early fatalities for Peach Bottom, 45 for Surry, and 

6.51 (not 18,000)2

8 Because STP and the Surry plant studied in SOARCA are both Westinghouse-designed PWRs 

9 with large dry containments, the insights gained from the SOARCA project regarding accident 

10 progression and offsite health consequences can generally be applied to the STP site.

4 for STP conditional on the occurrence of a hypothetical large source term 

5 being released. In addition, in SOARCA, the calculated individual long-term risks of dying from 

6 cancer from exposure to radiation from these accidents are very small—millions of times lower 

7 than the general risk of dying from cancer in the U.S. from all causes.

11 More information regarding the SOARCA project is available on NRC’s Web site at 

12 http://www.nrc.gov/about-nrc/regulatory/research/soar.html. 

13 A.1.6 Terrestrial or Aquatic Ecology

14 The original sources for the comments in this category can be found at the back of the Scoping 

15 Summary Report and are labeled with the following identifiers: 18-1, 20-3, 44-2, and 45-7. 

16 These comments are extracted from the original sources.

17 Comment 18-1: I want to touch on two aspects of the review. One is going to be the 

18 environmental aspect. It’s very important when you talk about Matagorda County—and I’ll do 

19 just a little bit of a commercial—we have a very, very sensitive area in that we have the 

20 freshwater from our Colorado River, two bays, estuaries, as well as the Gulf of Mexico. We are 

21 the North American Christmas bird count winner about [11] out of the last [12] years. It was 

22 foggy one morning, and we missed some of those birds. But, as you see that as we’ve got such 

23 a great ecological area here the whole time Units 1 and 2 have been operating. So, we’re very, 

24 very proud of the fact that the [STPNOC], with Units 1 and 2, continues to operate in a strong 

25 fashion while our environment is protected.

26 Comment 20-3: What should you focus on? Obviously, our environmental concerns are a huge 

27 part of this. I’m [with] the Convention and Visitors Bureau, and one of our main focuses is 

28 bringing tourists down to Matagorda County to see what we have to offer. Good thing one of 

29 our sights to see is STP, as well as all around STP we have tons of fishing, birding, we have 

30 farm lands and everything else, and from what I’ve seen, there have been no concerns with 

31 those at all, as I grew up fishing right below STP on the Colorado River. And, I would like to 

32 thank STP for providing that to me, providing the safe waters and the safe grounds for me to do 

33 that on.

34 Comment 44-2: In addition, the existing South Texas units need to be evaluated to see if they 

35 will need to be modified to meet the newly proposed cooling water requirements that the [EPA]

36 announced this week.

Comment 45-7

 

1 The 1982 Siting Study calculated 5.2 mean early fatalities for STP for the SST1 source term. This value is based upon a standard 

1,120 MWe PWR. When corrected for the actual electrical output (1410 MWe), the result is 6.5 mean early fatalities. 

37 : We are concerned about increasing tritium levels in wells [on site] and in the 

38 Colorado River. Extensive testing should occur for all organisms in the region, and exposure of 

39 whooping cranes to tritium and other radionuclides should be examined since they are an 

40 endangered species and their winter grounds are only 35 miles from the STP site.

2 The 1982 Siting Study calculated 18,000 early fatalities as the 99th percentile value conditional upon the SST1 source term 

release, assuming New York City meteorology and Indian Point population and wind rose as well as no evacuation. This was 

included as a sensitivity to show the effect of evacuation distance on early fatalities and was not meant to be a realistic estimate of 

the offsite health consequences of a severe nuclear reactor accident.
Appendix A

A-18

1 Response: 

2 These comments provided input (or data) for the staff’s environmental analysis of the ecology 

3 impacts of STP. The staff discusses these impacts in Sections 2.2.6, 2.2.7, 4.5, 4.6, 4.8, 8.1.4, 

4 8.1.5, 8.2.4, 8.2.5, 8.3.4, 8.3.5, 8.4.4, 8.4.5, 8.5.3, 8.7.4, and 8.7.5 of this SEIS. 

5 A.1.7 Uranium Fuel Cycle and Waste Management 

6 The original sources for the comments in this category can be found at the back of the Scoping 

7 Summary Report and are labeled with the following identifiers: 29-5, 32-4, 33-2, 34-1, 36-2, 

8 37-4, 39-5, 43-2, 45-5, 46-2, 47-3, 49-3, 51-4, 53-4, 54-4, 55-4, 59-4, 61-4, 62-5, 63-3, 64-2, 

9 69-4, 71-3, 75-3, 77-3, 79-3, 80-5. These comments are extracted from the original sources. In 

10 summary, these comments express concerns about transportation of radioactive materials, 

11 long-term stewardship of nuclear waste, and uranium mining. 

12 Comment 29-5: Whose backyard is the waste being transported through? [In] whose backyard 

13 is the waste being dumped?

14 Comment 32-4: Lastly, there is no way this can be justified as a result of the lack of safe 

15 storage for thousands and thousands of years of the nuclear waste. Please reject the renewal 

16 applications. The danger to our citizens is too great.

17 Comment 33-2: Uranium mining is a health issue. Nuclear waste remains a serious threat to 

18 future generations as well as the current population.

19 Comment 34-1: Please do not approve the licensing. Nuclear waste is too dangerous.

20 Comment 36-2: I also know, from following WCS in Andrews, Texas, that there is no safe 

21 disposal for LLRW [low-level radioactive waste], and still no safe disposal for the high-level 

22 waste fuel rods such as are melting in Japan today.

23 Comment 37-4: There is no adequate solution for radioactive waste, so it makes sense to stop 

24 generating more.

25 Comment 39-5: There is no adequate solution for radioactive waste, so it makes sense to stop 

26 generating more.

27 Comment 43-2: As we have seen in the last few weeks, nuclear energy is not as safe as made 

28 out to be, and there are too many problems with disposal that have not been solved.

29 Comment 45-5: It is time to stop generating more radioactive waste since there is no safe 

30 storage and disposal solution, even after attempts have been made for some [60] years. 

31 Relicensing would the creation of waste. There may not be enough room for even the so-called 

32 [LLRW] at the planned West Texas radioactive waste dump, since there is an attempt to allow 

33 Out of Compact waste[,] and the volume and curies limits may be reached long before all STP 

34 waste could be shipped. There is still no “high-level” repository for spent fuel rods.

35 Comment 46-2: I’m opposed to their continuation for all the usual reasons that any kind of 

36 accident and even a Category 4 or 5 hurricane-induced storm surge could remove external 

37 supports such as cooling ponds or water access (and who knows what hammering debris-laden 

38 waves on top of the storm surge could do), plus disposal of nuclear waste—no human 

39 technology is foolproof and totally isolated for thousands of years!

40 Comment 47-3: At the most fundamental level[,] we cannot justify generating more radioactive 

41 waste when there is no adequate solution for dealing with it.

42 Comment 49-3: Every nuclear power plant is a potential disaster waiting to happen[,] and every 

43 nuclear power plant is a long-term disaster by the toxic waste they generate.
Appendix A

A-19

1 Comment 51-4: There is no adequate solution for radioactive waste, so it makes no sense to 

2 continue generating more. 

3 Comment 53-4: There is no adequate solution for radioactive waste[,] so it makes no sense to 

4 continue generating more.

5 Comment 54-4: There is no adequate solution for radioactive waste, so it makes no sense to 

6 continue generating more.

7 Comment 55-4: [T]here is no adequate solution for radioactive waste, so it makes no sense to 

8 continue generating more. 

9 Comment 59-4: Until there is an adequate solution for radioactive waste, we should not 

10 continue to generate more.

11 Comment 61-4: There is no adequate solution for radioactive waste, so it makes no sense to 

12 continue generating more.

13 Comment 62-5: There is no adequate solution for radioactive waste, so it makes no sense to 

14 continue generating more.

15 Comment 63-3: What about waste? Radioactive waste is terrible to contend with.

Comment 64-2

17 These [...] dangerous radioactive waste! Is not safe. What are you going to do with the 

18 radioactive waste?

16 : Too much water is wasted! Way too much [water] daily to cool it!

19 Comment 69-4: There is no adequate solution for radioactive waste, so it makes no sense to 

20 continue generating more.

21 Comment 71-3: There is no solution for the disposal of radioactive waste, so it makes no sense 

22 to continue generating more. 

23 Comment 75-3: There is no adequate solution for radioactive waste, so it makes no sense to 

24 continue generating more.

25 Comment 77-3: Radioactive waste is and will continue to be a big problem[,] so why would we 

26 go in that direction. Leadership and creating thinking is needed at this moment in history. 

27 Please be part of solving problems and not adding new problems.

28 Comment 79-3: There is no adequate solution for radioactive waste, so it makes no sense to

29 continue generating more.

Comment 80-5

32 Response: These comments raise concerns about the uranium fuel cycle and waste 

33 management. The staff addresses the environmental impacts of the uranium fuel cycle and 

34 waste management in Chapter 6 of this SEIS. 

30 : There is no adequate solution for radioactive waste, so it makes no sense to 

31 continue generating more.

APPENDIX B 

NATIONAL ENVIRONMENTAL POLICY ACT ISSUES FOR LICENSE 

RENEWAL OF NUCLEAR POWER PLANTS

B-1 

1 NATIONAL ENVIRONMENTAL POLICY ACT ISSUES FOR LICENSE 

2 RENEWAL OF NUCLEAR POWER PLANTS

3 The table in this appendix summarizes the National Environmental Policy Act (NEPA) issues for 

4 license renewal of nuclear power plants identified in Table B–1 in Appendix B, Subpart A, to 

5 Title 10 Part 51 of the Code of Federal Regulations (10 CFR Part 51). Data supporting this 

6 table are contained in NUREG-1437, Generic Environmental Impact Statement for License 

7 Renewal of Nuclear Plants. Throughout this supplemental environmental impact statement 

8 (SEIS), “generic” issues are also referred to as Category 1 issues, and “site-specific” issues are 

9 also referred to as Category 2 issues.

10 Table B–1. Summary of Issues and Findings

Issue Type of Issue Finding

Surface Water Quality, Hydrology, and Use 

Impacts of 

refurbishment on 

surface water 

quality

Generic SMALL. Impacts are expected to be negligible during refurbishment 

because best management practices are expected to be employed to 

control soil erosion and spills.

Impacts of 

refurbishment on 

surface water use

Generic SMALL. Water use during refurbishment will not increase appreciably 

or will be reduced during plant outage.

Altered current 

patterns at intake 

and discharge 

structures

Generic SMALL. Altered current patterns have not been found to be a problem 

at operating nuclear power plants and are not expected to be a 

problem during the license renewal term.

Altered salinity 

gradients

Generic SMALL. Salinity gradients have not been found to be a problem at 

operating nuclear power plants and are not expected to be a problem 

during the license renewal term.

Altered thermal 

stratification of 

lakes

Generic SMALL. Generally, lake stratification has not been found to be a 

problem at operating nuclear power plants and is not expected to be a 

problem during the license renewal term.

Temperature 

effects on sediment 

transport capacity

Generic SMALL. These effects have not been found to be a problem at 

operating nuclear power plants and are not expected to be a problem 

during the license renewal term.

Scouring caused 

by discharged 

cooling water

Generic SMALL. Scouring has not been found to be a problem at most 

operating nuclear power plants and has caused only localized effects 

at a few plants. It is not expected to be a problem during the license 

renewal term.

Eutrophication Generic SMALL. Eutrophication has not been found to be a problem at 

operating nuclear power plants and is not expected to be a problem 

during the license renewal term.

Discharge of 

chlorine or other 

biocides

Generic SMALL. Effects are not a concern among regulatory and resource 

agencies, and are not expected to be a problem during the license 

renewal term.
Appendix B

B-2 

Issue Type of Issue Finding

Discharge of 

sanitary wastes 

and minor chemical 

spills

Generic SMALL. Effects are readily controlled through National Pollutant 

Discharge Elimination System (NPDES) permit and periodic 

modifications, if needed, and are not expected to be a problem during 

the license renewal term.

Discharge of other 

metals in 

wastewater

Generic SMALL. These discharges have not been found to be a problem at 

operating nuclear power plants with cooling-tower-based heatdissipation systems and have been satisfactorily mitigated at other 

plants. They are not expected to be a problem during the license 

renewal term.

Water use conflicts 

(plants with 

once-through 

cooling systems)

Generic SMALL. These conflicts have not been found to be a problem at 

operating nuclear power plants with once-through heat-dissipation 

systems.

Water use conflicts 

(plants with cooling 

ponds or cooling 

towers using 

makeup water from 

a small river with 

low flow)

Site-specific SMALL OR MODERATE. The issue has been a concern at nuclear 

power plants with cooling ponds and at plants with cooling towers. 

Impacts on instream and riparian communities near these plants could 

be of moderate significance in some situations. 

See §51.53(c)(3)(ii)(A).

Aquatic Ecology 

Refurbishment Generic SMALL. During plant shutdown and refurbishment, there will be 

negligible effects on aquatic biota because of a reduction of 

entrainment and impingement of organisms or a reduced release of 

chemicals.

Accumulation of 

contaminants in 

sediments or biota

Generic SMALL. Accumulation of contaminants has been a concern at a few 

nuclear power plants but has been satisfactorily mitigated by replacing 

copper alloy condenser tubes with those of another metal. It is not 

expected to be a problem during the license renewal term.

Entrainment of 

phytoplankton and 

zooplankton

Generic SMALL. Entrainment of phytoplankton and zooplankton has not been 

found to be a problem at operating nuclear power plants and is not 

expected to be a problem during the license renewal term.

Cold shock Generic SMALL. Cold shock has been satisfactorily mitigated at operating 

nuclear plants with once-through cooling systems, has not 

endangered fish populations, or been found to be a problem at 

operating nuclear power plants with cooling towers or cooling ponds, 

and is not expected to be a problem during the license renewal term.

Thermal plume 

barrier to migrating 

fish

Generic SMALL. Thermal plumes have not been found to be a problem at 

operating nuclear power plants and are not expected to be a problem 

during the license renewal term.

Distribution of 

aquatic organisms

Generic SMALL. Thermal discharge may have localized effects but is not 

expected to affect the larger geographical distribution of aquatic 

organisms.

Premature 

emergence of 

aquatic insects

Generic SMALL. Premature emergence has been found to be a localized 

effect at some operating nuclear power plants but has not been a 

problem and is not expected to be a problem during the license 

renewal term.
Appendix B

B-3 

Issue Type of Issue Finding

Gas 

supersaturation

(gas bubble 

disease)

Generic SMALL. Gas supersaturation was a concern at a small number of 

operating nuclear power plants with once-through cooling systems but 

has been satisfactorily mitigated. It has not been found to be a 

problem at operating nuclear power plants with cooling towers or 

cooling ponds and is not expected to be a problem during the license 

renewal term.

Low dissolved 

oxygen in the 

discharge

Generic SMALL. Low dissolved oxygen has been a concern at one nuclear 

power plant with a once-through cooling system but has been 

effectively mitigated. It has not been found to be a problem at 

operating nuclear power plants with cooling towers or cooling ponds 

and is not expected to be a problem during the license renewal term.

Losses from 

predation, 

parasitism, and 

disease among 

organisms exposed 

to sublethal 

stresses

Generic SMALL. These types of losses have not been found to be a problem 

at operating nuclear power plants and are not expected to be a 

problem during the license renewal term.

Stimulation of 

nuisance 

organisms 

(e.g.,shipworms)

Generic SMALL. Stimulation of nuisance organisms has been satisfactorily 

mitigated at the single nuclear power plant with a once-through 

cooling system where previously it was a problem. It has not been 

found to be a problem at operating nuclear power plants with cooling 

towers or cooling ponds and is not expected to be a problem during 

the license renewal term.

Aquatic Ecology (for Plants with Once-Through and Cooling-Pond Heat-Dissipation Systems)

Entrainment of fish 

and shellfish in 

early life stages

Site-specific SMALL, MODERATE, OR LARGE. The impacts of entrainment are 

small at many plants but may be moderate or even large at a few 

plants with once-through and cooling-pond cooling systems. Further, 

ongoing efforts in the vicinity of these plants to restore fish populations 

may increase the numbers of fish susceptible to intake effects during 

the license renewal period, such that entrainment studies conducted in 

support of the original license may no longer be valid. 

See §51.53(c)(3)(ii)(B).

Impingement of 

fish and shellfish

Site-specific SMALL, MODERATE, OR LARGE. The impacts of impingement are 

small at many plants but may be moderate or even large at a few 

plants with once-through and cooling-pond cooling systems. 

See §51.53(c)(3)(ii)(B).

Heat shock Site-specific SMALL, MODERATE, OR LARGE. Because of continuing concerns 

about heat shock and the possible need to modify thermal discharges 

in response to changing environmental conditions, the impacts may be 

of moderate or large significance at some plants. 

See §51.53(c)(3)(ii)(B).

Aquatic Ecology (for Plants with Cooling-Tower-Based Heat-Dissipation Systems)

Entrainment of fish 

and shellfish in 

early life stages

Generic SMALL. Entrainment of fish has not been found to be a problem at 

operating nuclear power plants with this type of cooling system and is 

not expected to be a problem during the license renewal term.

Impingement of 

fish and shellfish

Generic SMALL. The impingement has not been found to be a problem at 

operating nuclear power plants with this type of cooling system and is 
Appendix B

B-4 

Issue Type of Issue Finding

not expected to be a problem during the license renewal term.

Heat shock Generic SMALL. Heat shock has not been found to be a problem at operating 

nuclear power plants with this type of cooling system and is not 

expected to be a problem during the license renewal term.

Groundwater Use and Quality

Impacts of 

refurbishment on 

groundwater use 

and quality

Generic SMALL. Extensive dewatering during the original construction on 

some sites will not be repeated during refurbishment on any sites. 

Any plant wastes produced during refurbishment will be handled in the 

same manner as in current operating practices and are not expected 

to be a problem during the license renewal term.

Groundwater use 

conflicts (potable 

and service water; 

plants that use 

<100 gallons per 

minute (gpm)

Generic SMALL. Plants using less than 100 gpm are not expected to cause 

any groundwater use conflicts.

Groundwater use 

conflicts (potable 

and service water, 

and dewatering 

plants that use 

>100 gpm

Site-specific SMALL, MODERATE, OR LARGE. Plants that use more than 

100 gpm may cause groundwater use conflicts with nearby 

groundwater users. See §51.53(c)(3)(ii)(C).

Groundwater use 

conflicts (plants 

using cooling 

towers withdrawing 

makeup water from 

a small river)

Site-specific SMALL, MODERATE, OR LARGE. Water use conflicts may result 

from surface water withdrawals from small water bodies during low 

flow conditions which may affect aquifer recharge, especially if other 

groundwater or upstream surface water users come online before the 

time of license renewal. See §51.53(c)(3)(ii)(A).

Groundwater use 

conflicts (Ranney 

wells)

Site-specific SMALL, MODERATE, OR LARGE. Ranney wells can result in 

potential groundwater depression beyond the site boundary. Impacts 

of large groundwater withdrawal for cooling tower makeup at nuclear 

power plants using Ranney wells must be evaluated at the time of 

application for license renewal. See §51.53(c)(3)(ii)(C).

Groundwater 

quality degradation 

(Ranney wells)

Generic SMALL. Groundwater quality at river sites may be degraded by 

induced infiltration of poor-quality river water into an aquifer that 

supplies large quantities of reactor cooling water. However, the lower 

quality infiltrating water would not preclude the current uses of 

groundwater and is not expected to be a problem during the license 

renewal term.

Groundwater 

quality degradation 

(saltwater 

intrusion)

Generic SMALL. Nuclear power plants do not contribute significantly to 

saltwater intrusion.

Groundwater 

quality degradation 

(cooling ponds in 

salt marshes)

Generic SMALL. Sites with closed-cycle cooling ponds may degrade 

groundwater quality. Because water in salt marshes is brackish, this 

is not a concern for plants located in salt marshes.
Appendix B

B-5 

Issue Type of Issue Finding

Groundwater 

quality degradation 

(cooling ponds at 

inland sites)

Site-specific SMALL, MODERATE, OR LARGE. Sites with closed-cycle cooling 

ponds may degrade groundwater quality. For plants located inland, 

the quality of the groundwater in the vicinity of the ponds must be 

shown to be adequate to allow continuation of current uses. 

See §51.53(c)(3)(ii)(D).

Terrestrial Ecology

Refurbishment 

impacts

Site-specific SMALL, MODERATE, OR LARGE. Refurbishment impacts are 

insignificant if no loss of important plant and animal habitat occurs. 

However, it cannot be known whether important plant and animal 

communities may be affected until the specific proposal is presented 

with the license renewal application. See §51.53(c)(3)(ii)(E).

Cooling tower 

impacts on crops 

and ornamental 

vegetation

Generic SMALL. Impacts from salt drift, icing, fogging, or increased humidity 

associated with cooling tower operation have not been found to be a 

problem at operating nuclear power plants and are not expected to be 

a problem during the license renewal term.

Cooling tower 

impacts on native 

plants

Generic SMALL. Impacts from salt drift, icing, fogging, or increased humidity 

associated with cooling tower operation have not been found to be a 

problem at operating nuclear power plants and are not expected to be 

a problem during the license renewal term.

Bird collisions with 

cooling towers

Generic SMALL. These collisions have not been found to be a problem at 

operating nuclear power plants and are not expected to be a problem 

during the license renewal term.

Cooling pond 

impacts on 

terrestrial 

resources

Generic SMALL. Impacts of cooling ponds on terrestrial ecological resources 

are considered to be of small significance at all sites.

Powerline right-ofway (ROW) 

management 

(cutting and 

herbicide 

application)

Generic SMALL. The impacts of ROW maintenance on wildlife are expected 

to be of small significance at all sites.

Bird collisions with 

powerlines

Generic SMALL. Impacts are expected to be of small significance at all sites.

Impacts of 

electromagnetic 

fields on flora and 

fauna

Generic SMALL. No significant impacts of electromagnetic fields on terrestrial 

flora and fauna have been identified. Such effects are not expected to 

be a problem during the license renewal term.

Floodplains and 

wetland on 

powerline ROW

Generic SMALL. Periodic vegetation control is necessary in forested wetlands 

underneath powerlines and can be achieved with minimal damage to 

the wetland. No significant impact is expected at any nuclear power 

plant during the license renewal term.

Threatened and Endangered Species

Threatened or 

endangered 

species

Site-specific SMALL, MODERATE, OR LARGE. Generally, plant refurbishment 

and continued operation are not expected to adversely affect 

threatened or endangered species. However, consultation with 

appropriate agencies would be needed at the time of license renewal 
Appendix B

B-6 

Issue Type of Issue Finding

to determine whether or not threatened or endangered species are 

present and whether or not they would be adversely affected. 

See §51.53(c)(3)(ii)(E).

Air quality

Air quality during 

refurbishment 

(non-attainment 

and maintenance 

areas)

Site-specific SMALL, MODERATE, OR LARGE. Air quality impacts from plant 

refurbishment associated with license renewal are expected to be 

small. However, vehicle exhaust emissions could be cause for 

concern at locations in or near non-attainment or maintenance areas. 

The significance of the potential impact cannot be determined without 

considering the compliance status of each site and the number of 

workers expected to be employed during the outage. 

See §51.53(c)(3)(ii)(F).

Air quality effects 

of transmission 

lines

Generic SMALL. Production of ozone and oxides of nitrogen is insignificant 

and does not contribute measurably to ambient levels of these gases.

Land Use

Onsite land use Generic SMALL. Projected onsite land use changes required during 

refurbishment and the renewal period would be a small fraction of any 

nuclear power plant site and would involve land that is controlled by 

the applicant.

Powerline ROW Generic SMALL. Ongoing use of powerline ROWs would continue with no 

change in restrictions. The effects of these restrictions are of small 

significance.

Human Health

Radiation 

exposures to the 

public during 

refurbishment

Generic SMALL. During refurbishment, the gaseous effluents would result in 

doses that are similar to those from current operation. Applicable 

regulatory dose limits to the public are not expected to be exceeded.

Occupational 

radiation 

exposures during 

refurbishment

Generic SMALL. Occupational doses from refurbishment are expected to be 

within the range of annual average collective doses experienced for 

pressurized-water reactors and boiling-water reactors. Occupational 

mortality risk from all causes including radiation is in the mid-range for 

industrial settings.

Microbiological 

organisms 

(occupational 

health)

Generic SMALL. Occupational health impacts are expected to be controlled by 

continued application of accepted industrial hygiene practices to 

minimize exposure to workers.

Microbiological 

organisms (public 

health) (plants 

using lakes or 

canals, or cooling 

towers or cooling 

ponds that 

discharge to a 

small river)

Site-specific SMALL, MODERATE, OR LARGE. These organisms are not 

expected to be a problem at most operating plants except possibly at 

plants using cooling ponds, lakes, or canals that discharge to small 

rivers. Without site-specific data, it is not possible to predict the 

effects generically. See §51.53(c)(3)(ii)(G).
Appendix B

B-7 

Issue Type of Issue Finding

Noise Generic SMALL. Noise has not been found to be a problem at operating 

plants and is not expected to be a problem at any plant during the 

license renewal term.

Electromagnetic 

fields—acute 

effects (electric 

shock)

Site-specific SMALL, MODERATE, OR LARGE. Electrical shock resulting from 

direct access to energized conductors or from induced charges in 

metallic structures have not been found to be a problem at most 

operating plants and generally are not expected to be a problem 

during the license renewal term. However, site-specific review is 

required to determine the significance of the electric shock potential at 

the site. See §51.53(c)(3)(ii)(H).

Electromagnetic 

fields—chronic 

effects 

Uncategorized UNCERTAIN. Biological and physical studies of 60-hertz 

electromagnetic fields have not found consistent evidence linking 

harmful effects with field exposures. However, research is continuing 

in this area and a consensus scientific view has not been reached.

Radiation 

exposures to public 

(license renewal 

term)

Generic SMALL. Radiation doses to the public will continue at current levels 

associated with normal operations.

Occupational 

radiation 

exposures (license 

renewal term)

Generic SMALL. Projected maximum occupational doses during the license 

renewal term are within the range of doses experienced during normal 

operations and normal maintenance outages, and would be well below 

regulatory limits.

Socioeconomic Impacts

Housing impacts Site-specific SMALL, MODERATE, OR LARGE. Housing impacts are expected to 

be of small significance at plants located in a medium or high 

population area and not in an area where growth control measures 

that limit housing development are in effect. Moderate or large 

housing impacts of the workforce associated with refurbishment may 

be associated with plants located in sparsely populated areas or in 

areas with growth control measures that limit housing development. 

See §51.53(c)(3)(ii)(I).

Public services:

public safety, social 

services, and 

tourism and 

recreation

Generic SMALL. Impacts to public safety, social services, and tourism and 

recreation are expected to be of small significance at all sites.

Public services: 

public utilities

Site-specific SMALL OR MODERATE. An increased problem with water shortages 

at some sites may lead to impacts of moderate significance on public 

water supply availability. See §51.53(c)(3)(ii)(I).

Public services: 

education 

(refurbishment)

Site-specific SMALL, MODERATE, OR LARGE. Most sites would experience 

impacts of small significance but larger impacts are possible 

depending on site- and project-specific factors. See §51.53(c)(3)(ii)(I).

Public services: 

education (license 

renewal term)

Generic SMALL. Only impacts of small significance are expected.

Offsite land use 

(refurbishment)

Site-specific SMALL OR MODERATE. Impacts may be of moderate significance at 

plants in low population areas. See §51.53(c)(3)(ii)(I).
Appendix B

B-8 

Issue Type of Issue Finding

Offsite land use 

(license renewal 

term)

Site-specific SMALL, MODERATE, OR LARGE. Significant changes in land use 

may be associated with population and tax revenue changes resulting 

from license renewal. See §51.53(c)(3)(ii)(I).

Public services: 

transportation

Site-specific SMALL, MODERATE, OR LARGE. Transportation impacts (level of 

service) of highway traffic generated during plant refurbishment and 

during the term of the renewed license are generally expected to be of 

small significance. However, the increase in traffic associated with the 

additional workers and the local road and traffic control conditions may 

lead to impacts of moderate or large significance at some sites. 

See §51.53(c)(3)(ii)(J).

Historic and 

archaeological 

resources

Site-specific SMALL, MODERATE, OR LARGE. Generally, plant refurbishment 

and continued operation are expected to have no more than small 

adverse impacts on historic and archaeological resources. However, 

the National Historic Preservation Act requires the Federal agency to 

consult with the State Historic Preservation Officer to determine 

whether or not there are properties present that require protection. 

See §51.53(c)(3)(ii)(K).

Aesthetic impacts 

(refurbishment)

Generic SMALL. No significant impacts are expected during refurbishment.

Aesthetic impacts 

(license renewal 

term)

Generic SMALL. No significant impacts are expected during the license 

renewal term.

Aesthetic impacts 

of transmission 

lines (license 

renewal term)

Generic SMALL. No significant impacts are expected during the license 

renewal term.

Postulated Accidents

Design basis 

accidents

Generic SMALL. The staff has concluded that the environmental impacts of 

design-basis accidents are of small significance for all plants.

Severe accidents Site-specific SMALL. The probability weighted consequences of atmospheric 

releases, fallout onto open bodies of water, releases to groundwater, 

and societal and economic impacts from severe accidents are small 

for all plants. However, alternatives to mitigate severe accidents must 

be considered for all plants that have not considered such 

alternatives. See §51.53(c)(3)(ii)(L).

Uranium Fuel Cycle and Waste Management

Offsite radiological 

impacts (individual 

effects from other 

than the disposal of 

spent fuel and 

high-level waste)

Generic SMALL. Offsite impacts of the uranium fuel cycle have been 

considered by the Commission in Table S-3 of this part. Based on 

information in the GEIS, impacts on individuals from radioactive 

gaseous and liquid releases including radon-222 and technetium-99 

are small.

Offsite radiological 

impacts (collective 

effects)

Generic The 100-year environmental dose commitment to the U.S. population 

from the fuel cycle, high-level waste, and spent fuel disposal 

excepted, is calculated to be about 14,800 person rem, or 12 cancer 

fatalities, for each additional 20-year power reactor operating term. 

Much of this, especially the contribution of radon releases from mines 

and tailing piles, consists of tiny doses summed over large 
Appendix B

B-9 

Issue Type of Issue Finding

populations. This same dose calculation can theoretically be 

extended to include many tiny doses over additional thousands of 

years as well as doses outside the United States. The result of such a 

calculation would be thousands of cancer fatalities from the fuel cycle, 

but this result assumes that even tiny doses have some statistical 

adverse health effect which will not ever be mitigated (for example no 

cancer cure in the next thousand years), and that these doses 

projected over thousands of years are meaningful; however, these 

assumptions are questionable. In particular, science cannot rule out 

the possibility that there will be no cancer fatalities from these tiny 

doses. For perspective, the doses are very small fractions of 

regulatory limits, and even smaller fractions of natural background 

exposure to the same populations. 

Nevertheless, despite all the uncertainty, some judgment as to the 

regulatory NEPA implications of these matters should be made and it 

makes no sense to repeat the same judgment in every case. Even 

taking the uncertainties into account, the Commission concludes that 

these impacts are acceptable in that these impacts would not be 

sufficiently large to require the NEPA conclusion, for any plant, that 

the option of extended operation under 10 CFR Part 54 should be 

eliminated. Accordingly, while the Commission has not assigned a 

single level of significance for the collective effects of the fuel cycle, 

this issue is considered Category 1 (Generic).

Offsite radiological 

impacts (spent fuel 

and high-level 

waste disposal)

Generic Chapter 6 of this SEIS provides further discussion of these impacts.

Nonradiological 

impacts of the 

uranium fuel cycle

Generic SMALL. The nonradiological impacts of the uranium fuel cycle 

resulting from the renewal of an operating license for any plant are 

found to be small.

Low-level waste 

storage and 

disposal

Generic SMALL. The comprehensive regulatory controls that are in place and 

the low public doses being achieved at reactors ensure that the 

radiological impacts to the environment will remain small during the 

term of a renewed license. The maximum additional onsite land that 

may be required for low-level waste storage during the term of a 

renewed license and associated impacts will be small.

Nonradiological impacts on air and water will be negligible. The 

radiological and nonradiological environmental impacts of long-term 

disposal of low-level waste from any individual plant at licensed sites 

are small. In addition, the Commission concludes that there is 

reasonable assurance that sufficient low-level waste disposal capacity 

will be made available when needed for facilities to be 

decommissioned consistent with NRC decommissioning requirements.

Mixed waste 

storage and 

disposal

Generic SMALL. The comprehensive regulatory controls and the facilities and 

procedures that are in place ensure proper handling and storage, as 

well as negligible doses and exposure to toxic materials for the public 

and the environment at all plants. License renewal will not increase 

the small, continuing risk to human health and the environment posed 

by mixed waste at all plants. The radiological and nonradiological 

environmental impacts of long-term disposal of mixed waste from any 

individual plant at licensed sites are small. In addition, the 
Appendix B

B-10

Issue Type of Issue Finding

Commission concludes that there is reasonable assurance that 

sufficient mixed waste disposal capacity will be made available when 

needed for facilities to be decommissioned consistent with NRC 

decommissioning requirements.

Onsite spent fuel Generic SMALL. The expected increase in the volume of spent fuel from an 

additional 20 years of operation can be safely accommodated on site 

with small environmental effects through dry or pool storage at all 

plants if a permanent repository or monitored retrievable storage is not 

available.

Nonradiological 

waste

Generic SMALL. No changes to generating systems are anticipated for license 

renewal. Facilities and procedures are in place to ensure continued 

proper handling and disposal at all plants.

Transportation Generic SMALL. The impacts of transporting spent fuel enriched up to 

5 percent uranium-235 with average burnup for the peak rod to current 

levels approved by NRC up to 62,000 megawatt days per metric-ton 

uranium and the cumulative impacts of transporting high-level waste 

to a single repository, such as Yucca Mountain, Nevada are found to 

be consistent with the impact values contained in 10 CFR 51.52(c), 

Summary Table S–4, “Environmental Impact of Transportation of Fuel 

and Waste to and from One Light-Water-Cooled Nuclear Power 

Reactor.” If fuel enrichment or burnup conditions are not met, the 

applicant must submit an assessment of the implications for the 

environmental impact values reported in §51.52.

Decommissioning

Radiation doses Generic SMALL. Doses to the public will be well below applicable regulatory 

standards regardless of which decommissioning method is used. 

Occupational doses would increase no more than 1 man-rem caused 

by buildup of long-lived radionuclides during the license renewal term.

Waste 

management

Generic SMALL. Decommissioning at the end of a 20-year license renewal 

period would generate no more solid wastes than at the end of the 

current license term. No increase in the quantities of Class C or 

greater than Class C wastes would be expected.

Air quality Generic SMALL. Air quality impacts of decommissioning are expected to be 

negligible either at the end of the current operating term or at the end 

of the license renewal term.

Water quality Generic SMALL. The potential for significant water quality impacts from 

erosion or spills is no greater whether decommissioning occurs after a 

20-year license renewal period or after the original 40-year operation 

period, and measures are readily available to avoid such impacts.

Ecological 

resources

Generic SMALL. Decommissioning after either the initial operating period or 

after a 20-year license renewal period is not expected to have any 

direct ecological impacts.

Socioeconomic 

impacts

Generic SMALL. Decommissioning would have some short-term 

socioeconomic impacts. The impacts would not be increased by 

delaying decommissioning until the end of a 20-year relicense period, 

but they might be decreased by population and economic growth.
Appendix B

B-11

Issue Type of Issue Finding

Environmental Justice

Environmental 

justice

Uncategorized NONE. The need for and the content of an analysis of environmental 

justice will be addressed in plant-specific reviews.

Table source: Table B–1 in Appendix B, Subpart A, to 10 CFR Part 51

APPENDIX C 

APPLICABLE REGULATIONS, LAWS, AND AGREEMENTS

C-1 

1 APPLICABLE REGULATIONS, LAWS, AND AGREEMENTS

2 The Atomic Energy Act (AEA) authorizes the U.S. Nuclear Regulatory Commission (NRC) to 

3 enter into agreement with any state to assume regulatory authority for certain activities. For 

4 example, in accordance with Section 274 of the AEA, as amended, beginning on March 1, 1963, 

5 the State of Texas assumed regulatory responsibility over the following nuclear material usages: 

6 • byproduct materials as defined in Section 11e.(1) of the Act, 

7 • byproduct materials as defined in Section 11e.(2) of the Act, 

8 • source materials, and

9 • special nuclear materials in quantities not sufficient to form a critical mass. 

10 The Texas Department of State Health Services–Radiation Program administers the Texas 

11 Agreement State Program. 

12 In addition to implementing some Federal programs, state legislatures develop state laws, which 

13 are subject to applicable Federal statutes and regulations. State laws supplement, as well as 

14 implement, Federal laws for protection of air, water quality, and groundwater. State legislation 

15 may address solid waste management programs, locally rare or endangered species, and 

16 historic and cultural resources. 

17 The Clean Water Act (CWA) allows for primary enforcement and administration through state

18 agencies, provided the state program is at least as stringent as the Federal program. The state 

19 program must conform to the CWA and to the delegation of authority for the Federal National 

20 Pollutant Discharge Elimination System (NPDES) Program from the U.S. Environmental 

21 Protection Agency (EPA) to the state. In accordance with the CWA, for surface water, the 

22 primary mechanism to control water pollution is the requirement that directs dischargers 

23 (e.g., point source dischargers) to obtain an NPDES permit or, in the case of states where the 

24 authority has been delegated from EPA, a State Pollutant Discharge Elimination System 

25 (SPDES) permit.

26 C.1 Federal and State Environmental Requirements

27 Certain environmental requirements may have been delegated to state authorities for 

28 implementation, enforcement, or oversight by the applicable Federal agencies in exercising the 

29 agencies’ regulations. Table C–1 provides a list of STP licenses and permits needed for

30 compliance with the major requirements of the Texas environmental laws that affect the license 

31 renewal of South Texas Project (STP). These licenses and permits are addressed in this 

32 supplemental environmental impact statement (SEIS), pursuant to the NRC ESRP, Section 1.3, 

33 “Compliance and Consultations.” 

34 Table C–1. Licenses and Permits. 

Permit Number Dates Responsible Agency

License to operate STP, 

Unit 1 NPF-76

Issued: 3/22/1988

Expires: 8/20/2027

NRC

License to operate STP, 

Unit 2 NPF-80

Issued: 12/16/1988

Expires: 12/15/2028

NRC
Appendix C

C-2 

Permit Number Dates Responsible Agency

Hazardous materials 

shipments registration 0622110 550 067S

Issued: 6/29/2011

Expired: 6/30/2012

U.S. Department of 

Transportation

Permits for maintenance,

dredging (barge slip)

10570 Issued: 11/4/2004

Expires: 12/31/2014

U.S. Army Corps of

Engineers (USACE)

Permits for maintenance,

dredging (intake)

SWG-1992-02707

Issued: 7/21/2009

Expires: 12/31/2019

USACE

Texas Pollutant Discharge 

Elimination System Permit WQ0001908000

Issued: 4/5/2012

Expires: 12/1/2014

TCEQ

Air Permit (auxiliary 

boilers) 7410

Issued: 12/23/2004

Expires: 12/23/2014

TCEQ

Air Permit (emission 

sources) 0801

Issued: 1/18/2011

Expires: 1/18/2016

TCEQ

Registration of Industrial 

and Hazardous Waste

30651, EPA ID 

No. TXD020810503

Issued: 8/16/1976

Expires: Not applicable

TCEQ

Potable Water System

Texas Commission on 

Environmental Quality 

(TCEQ) ID 

No. 1610103/1610051

Issued: Not applicable

Expires: Not applicable

TCEQ

Source: STP License Renewal Application (STPNOC 2010).

1 C.2 References

2 Several operating permit applications may be prepared and submitted. Regulatory approval or 

3 permits or both would be received prior to license renewal approval by the NRC. As a 

4 convenient source of references of environmental requirements, Table C–2 lists representative 

5 Federal, state, and local approvals by the responsible agencies applicable to license renewal.

6 Table C–2. Federal, State, and Local Laws and Other Requirements. 

7 STP is subject to other requirements regarding various aspects of their environmental program. 

8 Representatives of those requirements are briefly described below.

License, Permit, or Other 

Required Approval (or Submittal)

Responsible 

Agency Authority Relevance

Air Quality Protection

Required for sources that are not 

exempt and are major sources, 

affected sources subject to the Acid 

Rain Program, sources subject to 

new source performance standards, 

or sources subject to National 

Emission Standards for Hazardous 

Air Pollutants

U.S. EPA or 

TCEQ

Texas Air Pollution 

Control 

Regulation—TX 

Administrative 

Code, Title 30

Nuclear Power plants are subject 

to 40 CFR Part 61, Subpart H, 

“National Emissions Standards 

for Emissions of Radionuclides,” 

which is included in the terms and 

conditions of the Title V 

Operating Permit.
Appendix C

C-3 

License, Permit, or Other 

Required Approval (or Submittal)

Responsible 

Agency Authority Relevance

Water Resources Protection

NPDES Permit—Construction Site 

Stormwater—required before 

making point source discharges of 

storm water from a construction 

project that disturbs more than 2 ha

(5 ac) of land

U.S. EPA or 

TCEQ

CWA 

(33 USC 1251 et 

seq.); 

40 CFR Part 122

Any plant refurbishment involving 

construction of more than 2 ha

(5 ac) of land would require a 

Stormwater Pollution Prevention 

Plan and Construction Site Storm 

Water Discharge Permit. 

NPDES Permit—Industrial Facility 

Stormwater—required before 

making point source discharges of 

storm water from an industrial site

U.S. EPA or 

TCEQ

CWA 

(33 USC 1251 et 

seq.); 

40 CFR Part 122

Stormwater would be discharged 

from the nuclear power plants 

during operations. Stormwater 

would discharge through existing 

outfalls covered by a permit.

NPDES Permit—Process Water 

Discharge—required before making 

point source discharges of industrial 

process wastewater

U.S. EPA or 

TCEQ

CWA 

(33 USC 1251 et 

seq.); 

40 CFR Part 122

Processed industrial wastewater 

would be discharged through 

existing outfalls covered by the 

permit.

Spill Prevention Control and 

Countermeasures Plan—required 

for any facility that could discharge 

diesel fuel in harmful quantities into 

navigable waters or onto adjoining 

shorelines

U.S. EPA or 

TCEQ

CWA 

(33 USC 1251 et 

seq.); 

40 CFR Part 112

A Spill Prevention Control and 

Countermeasures Plan is 

required at nuclear power plants 

storing large volumes of diesel 

fuel or other petroleum products

or both. 

CWA, Section 401, Water Quality 

Certification—required to be 

submitted to the agency 

responsible for issuing any Federal 

license or permit to conduct an 

activity that may result in a 

discharge of pollutants into waters 

of a state

U.S. EPA or 

TCEQ

CWA, Section 401 

(33 USC 1341); 

Certification for operation of a 

nuclear power plant may require 

a Federal license or permit 

(e.g., a CWA, Section 404, Permit

or a CWA, Section 401, Water 

Quality Certification). 

New Underground Storage Tanks 

System Registration—required 

within 30 days of bringing a new 

underground storage tank system 

into service

U.S. EPA or 

TCEQ

Resources 

Conservation and 

Recovery Act 

(RCRA), as 

amended, 

Subtitle I 

(42 USC 

6991a-6991i); 

40 CFR §280.22

This registration is required if new 

underground storage tank 

systems would be installed during 

refurbishment at a nuclear power 

plant.

Above Ground Storage Tank

Permit—required to install, remove, 

repair, or alter any stationary tank 

for the storage of flammable or 

combustible liquids

Applicable 

State Fire 

Marshal

This permit is required if new 

above-ground diesel fuel storage 

tanks would be installed during 

refurbishment at a nuclear power 

plant. In accordance with STP 

ER, there is no refurbishment.

Waste Management & Pollution Prevention

Registration and Hazardous Waste U.S. EPA or RCRA, as Generators of hazardous waste 
Appendix C

C-4 

License, Permit, or Other 

Required Approval (or Submittal)

Responsible 

Agency Authority Relevance

Generator Identification Number—

required before a person who 

generates over 100 kg (220 lb) per 

calendar month of hazardous waste 

ships the hazardous waste off site

TCEQ amended 

(42 USC 6901 et 

seq.), Subtitle C 

must notify EPA that the wastes 

exist and require management in 

compliance with RCRA.

Hazardous Waste Facility Permit—

required if hazardous waste will 

undergo nonexempt treatment by 

the generator; be stored on site for 

longer than 90 days by the 

generator of 1,000 kg (2,205 lb) or 

more of hazardous waste per 

month; be stored on site for longer 

than 180 days by the generator of 

between 100 and 1,000 kg (220 

and 2,205 lb) of hazardous waste 

per month; be disposed of on site; 

or be received from off site for 

treatment or disposal

U.S. EPA or 

TCEQ

RCRA, as 

amended 

(42 USC 6901 et 

seq.), Subtitle C

Hazardous wastes are usually not 

disposed of on site at nuclear 

power plants. Hazardous wastes 

generated on site are not 

generally stored for more than 

90 days. However, should a 

nuclear power plant store wastes 

on site for greater than 90 days 

for characterization, profiling, or 

scheduling for treatment or 

disposal, a Hazardous Waste 

Facility Permit would be required.

Emergency Planning & Response

List of Material Safety Data 

Sheets—submission required for 

hazardous chemicals (as defined in 

29 CFR Part 1910) that are stored 

on site in excess of their threshold 

quantities

State and local 

emergency 

planning 

agencies

(State 

Emergency

Response 

Commission or 

SERC) 

Emergency 

Planning and 

Community Rightto-Know Act of 

1986 (EPCRA), 

Section 311 

(42 USC 11021); 

40 CFR §370.20

Nuclear power plant operators 

are required to submit List of 

Material Safety Data Sheets to 

state and local emergency 

planning agencies.

Annual Hazardous Chemical 

Inventory Report—submission 

required when hazardous 

chemicals have been stored at a 

facility during the preceding year in 

amounts that exceed threshold 

quantities

State and local 

emergency 

response 

agencies

(SERC); local 

fire department

EPCRA, 

Section 312 

(42 USC 11022); 

40 CFR §370.25

If hazardous chemicals have 

been stored at a nuclear power 

plant during the preceding year in 

amounts that exceed threshold 

quantities, plant operators would 

be required to submit an Annual 

Hazardous Chemical Inventory 

Report.

Notification of On-Site Storage of 

an Extremely Hazardous 

Substance—submission required 

within 60 days after onsite storage 

begins of an extremely hazardous 

substance in a quantity greater than 

the threshold planning quantity

State and local 

emergency 

response 

agencies

(SERC)

EPCRA, 

Section 304 

(42 USC 11004); 

40 CFR §355.30

If an extremely hazardous 

substance stored at a nuclear 

power plant in a quantity greater 

than the threshold planning 

quantity, plant operators would 

prepare and submit the 

Notification of On-Site Storage of 

an Extremely Hazardous 

Substance.

Annual Toxics Release Inventory 

Report—required for facilities that 

have 10 or more full-time 

U.S. EPA or 

TCEQ

EPCRA, 

Section 313 

(42 USC 11023); 

If required, nuclear power plant 

operators would prepare and 

submit a Toxics Release 
Appendix C

C-5 

License, Permit, or Other 

Required Approval (or Submittal)

Responsible 

Agency Authority Relevance

employees and are assigned 

certain standards

40 CFR Part 372 Inventory Report to EPA.

Industrial Classification codes.

Transportation of Radioactive 

Wastes and Conversion Products 

Packaging, Labeling, and Routing 

Requirements for Radioactive 

Materials—required for packages 

containing radioactive materials that 

will be shipped by truck or rail

U.S. 

Department of 

Transportation

Hazardous 

Material 

Transportation Act

(HMTA) 

(49 USC 1501 et 

seq.); AEA, as 

amended (42 USC 

2011 et seq.); 

49 CFR Parts 172, 

173, 174, 177, 

and 397

When shipments of radioactive 

materials are made, nuclear 

power plant operators would 

comply with U.S. Department of 

Transportation packaging, 

labeling, and routing 

requirements.

Biotic Resource Protection

Threatened and Endangered 

Species Consultation—required 

between the responsible Federal 

agencies and affected states to 

ensure that the project is unlikely to

jeopardize the continued existence 

of any species listed at the Federal 

or state level as endangered or 

threatened or result in destruction 

of critical habitat of such species

U.S. Fish and 

Wildlife Service 

(FWS) and 

other 

applicable 

state agencies

(listed in 

Appendix D of 

this SEIS)

Endangered 

Species Act of 

1973, as amended 

(16 USC 1531 et 

seq.)

The NRC would consult with the 

FWS and state agencies 

regarding the impact of license 

renewal on threatened or 

endangered species or their 

critical habitat.

CWA, Section 404, (Dredge and 

Fill) Permit—required to place 

dredged or fill material into waters 

of the U.S., including areas 

designated as wetlands, unless 

such placement is exempt or 

authorized by a Nationwide permit 

or a regional permit (A notice must 

be filed if a Nationwide or regional 

permit applies.)

USACE CWA 

(33 USC 1251 et 

seq.); 

33 CFR Parts 323 

and 330

Any dredging or placement of fill 

material into wetlands within the 

jurisdiction of the USACE at a 

nuclear power plant would require 

a Section 404 permit.

Cultural Resources Protection

Archaeological and Historical 

Resources Consultation—required 

before a Federal agency approves 

a project in an area where 

archaeological or historic resources 

might be located

State Historic 

Preservation 

Officer or 

Tribal Historic 

Preservation 

Officer or both

(listed in 

Appendix D of 

this SEIS)

National Historic 

Preservation Act of 

1966, as amended 

(16 USC 470 et 

seq.); 

Archaeological 

and Historical 

Preservation Act of 

1974 

(16 USC 469-

469c-2); 

Antiquities Act of 

The NRC would consult with the 

State or Tribal Historic 

Preservation Officers or both and 

applicable Indian tribes 

(e.g., tribes that have historical 

ties to the land) regarding the 

impacts of license renewal and 

the results of archaeological and 

architectural surveys of nuclear 

power plant site.
Appendix C

C-6 

License, Permit, or Other 

Required Approval (or Submittal)

Responsible 

Agency Authority Relevance

1906 

(16 USC 431 et 

seq.); 

Archaeological 

Resources 

Protection Act of 

1979, as amended 

(16 USC 470aamm)

 1 
APPENDIX D 

CONSULTATION CORRESPONDENCE

D-1 

CONSULTATION CORRESPONDENCE

D.1 Background

The Endangered Species Act of 1973, as amended; the Magnuson–Stevens Fisheries 

Management Act of 1996, as amended; and the National Historic Preservation Act of 1966 

(NHPA) require that Federal agencies consult with applicable state and Federal agencies and 

groups before taking action that may affect threatened or endangered species, essential fish 

habitat, or historic and archaeological resources, respectively. Table D–1 contains a list of 

correspondence between the NRC and other agencies in compliance with these Federal acts. 

Table D–1. Consultation Correspondence

Author Recipient Date of Letter/Email

NRC (B. Pham) Advisory Council on Historic Preservation (D. Klima) January 27, 2011 

(ML110190591)

NRC (B. Pham) Tribal Nation—Ysleta del Sur Pueblo (J. Loera) February 9, 2011 

(ML110190385)

NRC (B. Pham) Tribal Nation—Alabama–Coushatta Tribe (O. Sylestine) February 9, 2011 

(ML110190418)

NRC (B. Pham) Tribal Nation—Kiowa Tribe of Oklahoma (B. Horse) February 9, 2011 

(ML110390244)

NRC (B. Pham) Tribal Nation—Comanche Nation (R. Toahty) February 9, 2011 

(ML110390265)

NRC (B. Pham) U.S. Fish & Wildlife Service (M. Orms) February 16, 2011 

(ML110190429)

NRC (B. Pham) National Marine Fisheries Service (D. Bernhart) February 16, 2011 

(ML110190434)

NRC (B. Pham) Texas Parks & Wildlife Department (K. Boydston) February 16, 2011 

(ML110190571)

NRC (B. Pham) State Historic Preservation Officer (M. Wolfe) February 17, 2011 

(ML110190549)

NRC (B. Pham) Tribal Nation—Tonkawa Tribe of Oklahoma (A. Street) February 17, 2011 

(ML110390321)

NRC (B. Pham) Tribal Nation—Apalachicola Band of Creek Indians 

(M. Blount)

February 17, 2011 

(ML110390321)

NRC (B. Pham) Tribal Nation—Lipan Apache Tribe of Texas 

(B. Barcena Jr.)

February 17, 2011 

(ML110390321)

NRC (B. Pham) Tribal Nation—Lipan Apache Band of Texas 

(D. Romero Jr.)

February 17, 2011 

(ML110390321)

NRC (B. Pham) Tribal Nation—Pamaque Clan of Coahuila Y Tejas 

(J. Mendoza)

February 17, 2011 

(ML110390321)

NRC (B. Pham) Tribal Nation—Tap Pilam-Coahuiltecan Nation 

(R. Hernandez)

February 17, 2011 

(ML110390321)
Appendix D

D-2 

Author Recipient Date of Letter/Email

NRC (B. Pham) Tribal Nation—Kickapoo Traditional Council (J. Garza Jr.) February 23, 2011 

(ML110240161)

Tribal Nation—

Tonkawa Tribe of 

Oklahoma (M. Allen)

NRC (Chief, Rules, Announcements, & Directives Branch) February 15, 2011 

(ML110490057)

National Marine 

Fisheries Service 

(T. Mincey)

NRC (T. Tran) March 3, 2011 

(ML110690848)

Tribal Nation—

Apalachicola Band of

Creek Indians 

(M. Blount)

NRC (Chief, Rules, Announcements, & Directives Branch) March 7, 2011 

(ML110750424)

Tribal Nation—

Kickapoo Traditional 

Council (J. Garza Jr.)

NRC (Chief, Rules, Announcements, & Directives Branch) April 1, 2011 

(ML110980503)

Tribal Nation—Tap 

Pilam–Coahuiltecan 

Nation (R. Hernandez)

NRC (Chief, Rules, Announcements, & Directives Branch) April 1, 2011 

(ML11111A134)

Texas Parks & Wildlife 

Department 

(A. Turner)

NRC (B. Pham) April 20, 2011 

(ML11119A009)

U.S. Fish & Wildlife 

Service (M. Orms) NRC (T. Tran) June 2, 2011(ML11173A235)

State Historic 

Preservation Officer

(Bill Martin)

NRC (T. Tran) September 13, 2011 

(ML11259A029)

NRC (D. Wrona) Tribal Nation—Kickapoo Traditional Council (J. Garza Jr.) November 17, 2011 

(ML11269A011)

NRC (D. Wrona) Tribal Nation— Tonkawa Tribe of Oklahoma (M. Allen) November 17, 2011 

(ML11269A015)

NRC (D. Wrona) Tribal Nation—Tap 

Pilam–Coahuiltecan Nation (R. Hernandez)

November 29, 2011 

(ML11269A112)

NRC (D. Wrona) Tribal Nation—Apalachicola Band of Creek Indians 

(M. Blount)

January 19, 2012 

(ML11269A063)

D.2 Consultation Correspondence

The following pages contain copies of the letters listed in Table D–1. 
Appendix D

D-3 
Appendix D

D-4 
Appendix D

D-5 
Appendix D

D-6 
Appendix D

D-7 
Appendix D

D-8 
Appendix D

D-9 
Appendix D

D-10
Appendix D

D-11
Appendix D

D-12
Appendix D

D-13
Appendix D

D-14
Appendix D

D-15
Appendix D

D-16
Appendix D

D-17
Appendix D

D-18
Appendix D

D-19
Appendix D

D-20
Appendix D

D-21
Appendix D

D-22
Appendix D

D-23
Appendix D

D-24
Appendix D

D-25
Appendix D

D-26
Appendix D

D-27
Appendix D

D-28
Appendix D

D-29
Appendix D

D-30
Appendix D

D-31
Appendix D

D-32
Appendix D

D-33
Appendix D

D-34
Appendix D

D-35
Appendix D

D-36
Appendix D

D-37
Appendix D

D-38
Appendix D

D-39
Appendix D

D-40
Appendix D

D-41
Appendix D

D-42
Appendix D

D-43
Appendix D

D-44
Appendix D

D-45
Appendix D

D-46
Appendix D

D-47
Appendix D

D-48
Appendix D

D-49
Appendix D

D-50
Appendix D

D-51
Appendix D

D-52
Appendix D

D-53
Appendix D

D-54
Appendix D

D-55
Appendix D

D-56
Appendix D

D-57
Appendix D

D-58
Appendix D

D-59
Appendix D

D-60
Appendix D

D-61
Appendix D

D-62

 
Appendix D

D-63
Appendix D

D-64

 
Appendix D

D-65
Appendix D

D-66
Appendix D

D-67
Appendix D

D-68
Appendix D

D-69
Appendix D

D-70
APPENDIX E 

CHRONOLOGY OF ENVIRONMENTAL REVIEW CORRESPONDENCE

E-1 

1 CHRONOLOGY OF ENVIRONMENTAL REVIEW CORRESPONDENCE

2 This appendix contains a chronological listing of correspondence between the U.S. Nuclear 

3 Regulatory Commission (NRC) and external parties as part of its environmental review for the 

4 South Texas Project (STP). All documents, with the exception of those containing proprietary 

5 information, are available electronically from the NRC’s Public Electronic Reading Room, which 

6 is found on the Internet at the following web address: http://www.nrc.gov/reading-rm.html. 

7 From this site, the public can gain access to the NRC’s Agencywide Documents Access and 

8 Management System (ADAMS), which provides text and image files of NRC’s public 

9 documents. The ADAMS accession number for each document is included below.

10 E.1 Environmental Review Correspondence

11 Table E–1 lists the environmental review correspondence in date order beginning with the 

12 request by South Texas Project Nuclear Operating Company (STPNOC) to renew the operating 

13 licenses for STP.

14 Table E–1. Environmental Review Correspondence

Date Correspondence Description ADAMS No.

10/25/10 STP, Units 1 and 2, Transmittal of LRA ML103010257

11/4/10 Press Release-10-202, “NRC Announces Availability of License Renewal 

Application for South Texas Project Nuclear Power Plant” 

ML103081029

11/23/10 Maintenance of Reference Materials at the Bay City Public Library for the 

Review of STP License Renewal Application

ML103090389

11/23/10 Receipt and availability of the LRA For STP, Units 1 and 2 (LTR) ML103020399

12/9/10 Project Manager Change for the License Renewal of STP, Units 1 and 2 (TAC 

No. ME4936)

ML103410524

1/6/11 Acceptance of LRA for STP, Units 1 and 2 ML103440610

1/7/11 Determination of acceptability and sufficiency for docketing, proposed review 

schedule, and opportunity for a hearing regarding the application from STPNOC

for renewal of the operating licenses for STP electric gene

ML103420531

1/7/11 Notice of acceptance for docketing of the application and notice of opportunity for 

hearing regarding renewal of facility operating license numbers NPF-76 and 

NPF-80 for an additional 20-year period STPNOC, STP

ML103420650

1/13/11 Press Release-11-009: “NRC Announces Opportunity for Hearing on Application 

to Renew Operating Licenses for South Texas Project Nuclear Power Plant” 

ML110130500

1/21/11 Notice of intent to prepare an environmental impact statement (EIS) and conduct 

scoping process for license renewal for STP, Units 1 and 2 

ML103490511

1/25/11 3/2/11—forthcoming meeting to discuss the license renewal process and 

environmental scoping for STP, Units 1 and 2, LRA review

ML103510697

1/27/11 STP, Units 1 and 2, LRA review (ACHP) ML110190591

1/31/11 Comment (44) of Edmund E. Kelley, opposing STP, Units 1 and 2, LRA review ML11105A023

1/31/11 Comment (51) of Juan Aguilar, on behalf of self, opposed to relicensing of STP, 

Units 1 and 2 

ML11119A011
Appendix E

E-2 

Date Correspondence Description ADAMS No.

1/31/11 Comment (52) of Juan Aguilar, on behalf of self, opposing STP, Units 1 and 2, 

relicensing application

ML11119A012

1/31/11 Comment (54) of Shawn Tracy, on behalf of self, opposing STP, Units 1 and 2, 

relicensing application

ML11119A014

2/7/11 Press Release-11-017: “NRC to Meet with Public March 2 for Input on South 

Texas Project Nuclear Plant Environmental Review for License Renewal” 

ML110380405

2/9/11 Comanche Nation—request for comments concerning the STP, Units 1 and 2, 

LRA review

ML110390265

2/9/11 Kiowa Tribe of Oklahoma—Request for comments concerning the STP, Units 1 

and 2, LRA review

ML110390244

2/9/11 Ysleta del Sur Pueblo—Request for comments concerning the STP, Units 1 and 

2, LRA review

ML110190385

2/9/11 Alabama-Coushatta Tribe—Request for comments concerning the STP, Units 1 

and 2, LRA review

ML110190418

2/15/11 Comment (1) of Miranda Allen, on behalf of the Tonkawa Tribe of Oklahoma on 

request for comments concerning the STP, Units 1 and 2, LRA review

ML110490057

2/16/11 Request for list of Federally protected species and important habitats within the 

area under evaluation for the STP, Units 1 and 2, license renewal (FWS)

ML110190429

2/16/11 Request for list of Federally protected species and important habitats within the 

area under evaluation for the STP, Units 1 and 2, LRA review (NMFS) 

ML110190434

2/16/11 Request for list of state-protected species and important habitats within the area 

under evaluation for the STP, Units 1 and 2, LRA review (Texas Parks and 

Wildlife Department) 

ML110190571

2/17/11 Request for comments concerning the STP, Units 1 and 2, LRA review (Tribes) ML110390321

2/17/11 STP, Units 1 and 2, LRA online reference portal ML110610201

2/17/11 STP, Units 1 and 2, LRA review (SHPO) ML110190549

2/23/11 Kickapoo Traditional Council—Request for comments concerning the STP, Units 

1 and 2, LRA review

ML110240161

2/28/11 Comment (46) of Randy K. Weber, on behalf of Texas House of 

Representatives, supporting license renewal for STP, Units 1 and 2 

ML11108A059

2/28/11 Schedule for the conduct of review of the STP, Units 1 and 2, LRA ML110340478

3/3/11 3/3/11—NRR e-mail capture—STP (NMFS) ML110690848

3/7/11 Comment (3) of Mary Sixwomen Blount, on behalf of Apalachicola Creek Indians, 

on STP, Units 1 and 2, LRA

ML110750424

3/11/11 Comment (2) of Vicki Adams, approving notice of intent to prepare an EIS and 

conduct the scoping process for STP, Units 1 and 2

ML110730188

3/14/11 Declaration of Karen Hadden on behalf of SEED Coalition ML110740852

3/14/11 Declaration of Susan Dancer on behalf of SEED Coalition ML110740850

3/14/11 Notice of appearance of Susan Dancer on behalf of SEED Coalition ML110740851

3/14/11 Petition for leave to intervene and request for hearing of SEED Coalition and 

Susan Dancer

ML110740848

3/16/11 Referral memorandum of the Secretary to the Board regarding license 

application request for STPNOC, STP, Units 1 and 2 

ML110750603
Appendix E

E-3 

Date Correspondence Description ADAMS No.

3/17/11 Referral memorandum of the Secretary to the Board regarding license 

application request for STPNOC, STP, Units 1 and 2 (reissued) 

ML110760289

3/17/11 STP, Units 1 and 2, LRA online reference portal ML110620203

3/23/11 Establishment of Atomic Safety and Licensing Board in the matter of STPNOC, 

STP, Units 1 and 2, license renewal

ML110820735

3/24/11 Comment (31) of Jennifer Meador, opposing relicensing of STP, Units 1 and 2 ML111010604

3/28/11 Comment (34) of unknown individual, supporting nuclear power and relicensing 

of STP, Units 1 and 2 

ML111010507

3/28/11 Comment (37) of Carolyn Campbell, opposing STP, Units 1 and 2, relicensing

(NRC-2010-0375)

ML111010510

3/28/11 Comment (48) of Beth Ann Larsen, on behalf of self, opposing STP, Units 1 

and 2, relicensing application

ML11119A007

3/28/11 Comment (49) of Dzan Nguyen, opposed to relicensing STP, Units 1 and 2 ML11119A008

3/28/11 Comment (55) of Kelly Simon, on behalf of self, opposing relicensing of STP

nuclear reactors

ML11119A015

3/28/11 Comment (58) of Cynthia Gebhardt, on behalf of self, opposing STP, Units 1 

and 2, relicensing application

ML11119A018

3/28/11 Comment (59) of Rory Holcomb, on behalf of self, opposing STP, Units 1 and 2, 

relicensing application

ML11119A019

3/29/11 Comment (4) of Julie Sharp, on behalf of National Park Service, in regards to 

STPNOC STP with determination that no park units will be affected

ML110910179

3/30/11 Comment (32) Of Joy Malacara, opposing relicensing of STP, Units 1 and 2 ML111010479

3/30/11 Comment (33) of Melanie and David Winters, opposing STP, Units 1 and 2,

relicensing

ML111010506

3/30/11 Comment (35) of Christine Fry, opposing STP, Units 1 and 2, relicensing

(NRC-2010-0375) 

ML111010508

3/30/11 Comment (36) of Leona A. Slodge, opposing STP, Units 1 and 2, relicensing ML111010509

3/30/11 Comment (39) of B. Dunlap and T. Rinehart, opposing relicensing of STP, Units 

1 and 2

ML111010517

3/30/11 Comment (40) of Peggy Cravens, opposing the relicensing of STP, Units 1 and 2 ML111010518

3/30/11 Comment (53) of Douglas S. McArthur, opposing relicensing of STP ML11119A013

3/30/11 Comment (6) of Eva Esparza, opposing STPNOC’s notice of intent to prepare an 

EIS and conduct the scoping process for STP, Units 1 and 2

ML110960078

3/30/11 Comment (60) of unknown individual on behalf of self, opposing relicensing of 

STP, Units 1 and 2, for an additional 20 years

ML11119A020

3/30/11 Comment (7) of Darby Riley, regarding notice of intent to prepare an EIS and 

conduct the scoping process for STP, Units 1 and 2 

ML110960079

3/30/11 Comment (38) of Melanie Sallis, opposing the relicensing of STP, Units 1 and 2 ML11273A082

3/31/11 Comment (10) of Karen Seal, opposing the licensing of STP, Units 1 and 2 ML110960082

3/31/11 Comment (5) of Peggy Pryor, opposing STP plants ML110960077

3/31/11 Comment (8) of Kamala Platt, opposing STP relicensing ML110960080
Appendix E

E-4 

Date Correspondence Description ADAMS No.

3/31/11 Comment (9) of Marion Mlotok, opposing the renewal of STP, Units 1 and 2 ML110960081

4/1/11 Comment (11) of Kassandra Levay, opposing STPNOC’s notice of intent to 

prepare an EIS and conduct the scoping process for STP, Units 1 and 2

ML110960083

4/1/11 Comment (12) of unknown individual, regarding notice of intent to prepare an EIS

and conduct the scoping process for STP, Units 1 and 2

ML110960084

4/1/11 Comment (13) of T. Burns, opposing South Texas plants (NRC-2010-0375) ML110960086

4/1/11 Comment (14) of Jolly J. Clark, opposing the relicensing of STP, Units 1 and 2 ML110960087

4/1/11 Comment (15) of Pat Bulla, regarding the decommissioning of STP, Units 1 

and 2, not relicensing it

ML110960088

4/1/11 Comment (16) of William Stout, supporting the decommissioning of STP, Units 1 

and 2, not relicensing it

ML110960089

4/1/11 Comment (19) of Carol Geiger, opposing the renewal of STP, Units 1 and 2, 

licensing

ML110960092

4/1/11 Comment (20) of Veryan Thompson, supporting STP, Units 1 and 2, 

decommissioning and denying its LRA

ML110960093

4/1/11 Comment (21) of Robert Singleton, opposing license extension for STP, Units 1 

and 2 

ML110960094

4/1/11 Comment (22) of Karen Hadden, on behalf of sustainable energy and economic 

development coalition, opposing relicensing of STP, Units 1 and 2 

ML110960095

4/1/11 Comment (23) of Alan Alan Apurim, opposing relicensing of STP, Units 1 and 2 ML110960096

4/1/11 Comment (24) of Brandi Clark Burton, on behalf of self, opposing STP, Units 1 

and 2, extending its license application renewal for public safety and 

environmental reasons

ML110960097

4/1/11 Comment (25) of Carol Geiger, on behalf of self, opposing STP, Units 1 and 2, 

extending its license application renewal

ML110960098

4/1/11 Comment (27) of Juan Garza, on behalf of Kickapoo Traditional Tribe of Texas, 

on the STP, Units 1 and 2, LRA review

ML110980503

4/1/11 Comment (45) of Maria Hogan, on safety standards of STP, Units 1 and 2, being

followed

ML11105A020

4/1/11 Comment (47) of Miguel Acosta, on behalf of Raymond Hernandez of Tap Pilam 

Coahuiltecan Nation, opposing the renewal license for STP, Units 1 and 2

ML11111A134

4/4/11 Comment (17) of C.J. Keudell, opposing the relicensing of STP, Units 1 and 2 ML110960090

4/4/11 Comment (18) of Tarek Tonsson, opposing the relicensing of STP, Units 1 and 2 ML110960091

4/4/11 Comment (26) of Eric Lane, on behalf of self, opposing STP, Units 1 and 2, 

extending its license application renewal

ML110960099

4/5/11 Project Manager change for the license renewal of STP, Units 1 and 2 (TAC 

No. ME4938)

ML110872079

4/7/11 4/7/11—Notice of appearance of Steven P. Frantz (STPNOC) ML110970467

4/7/11 4/7/11—The NRC staff’s answer to petition for leave to intervene and request for 

hearing of SEED Coalition and Susan Dancer

ML110970659

4/7/11 STPNOC’s answer opposing request for hearing and petition for leave to 

intervene

ML110970544
Appendix E

E-5 

Date Correspondence Description ADAMS No.

4/8/11 Comment (28) of Jenna Findley, opposing STP, Units 1 and 2, relicensing 

(NRC-2010-0375)

ML111010476

4/8/11 Comment (29) of Margaret Reed, opposing the relicensing of STP, Units 1 and 2 ML111010477

4/8/11 Comment (30) of Scott and Cyndy Reynolds, opposing relicensing of STP 

Nuclear reactors

ML111010478

4/9/11 Comment (43) of Thomas Nehms, opposing the relicensing of STP, Units 1 

and 2 

ML111010521

4/11/11 Comment (41) of Shannon Jurak, opposing the relicensing of STP, Units 1 and 2 ML111010519

4/11/11 Comment (42) of Thomas Nelms, opposing the relicensing of STP, Units 1 and 2 ML111010520

4/20/11 Comment (61) of Amy Turner, on behalf of Texas Parks and Wildlife, on 

proposed license renewal of STP, Units 1 and 2, Matagorda County, TX

ML11119A009

4/26/11 Comment (50) of John Trimble, opposing relicensing of STP, Units 1 and 2 

(NRC-2010-0375) 

ML11119A010

4/26/11 Comment (56) of unknown individual, opposing STP, Units 1 and 2, LRA ML11119A016

4/26/11 Comment (57) of Judy Moore, on behalf of self, opposing relicensing of STP

nuclear reactors

ML11119A017

5/5/11 Notice of withdrawal of Megan Wright in the matter of STP, Units 1 and 2 ML111250147

5/8/11 Interveners request for oral argument on contentions raised on relicensing ML111280003

5/8/11 Petitioners’ proposed amended petition for leave to intervene and request for 

hearing of SEED Coalition and Susan Dancer

ML111280002

5/9/11 Notice of withdrawal of Emily Monteith ML111290341

5/11/11 Certificate of service for amended petition to intervene and request for hearing ML111310798

5/11/11 Certificate of service for request for oral hearing ML111310800

5/19/11 Summary of meeting with stakeholders to discuss issues related to the review of 

the STP, Units 1 and 2, LRA

ML110770661

5/23/11 Memorandum (notice pursuant to 10 CFR § 2.309(i)) ML111430828

5/23/11 Order (scheduling oral argument) ML111430799

5/31/11 RAIs for the review of the STP LRA ML11140A015

6/2/11 U.S. Fish and Wildlife Service Consultation #65533—STPNOC ML11173A235

6/2/11 The NRC staff’s answer to proposed amended petition for leave to intervene and 

request for hearing of SEED Coalition and Susan Dancer

ML111530393

6/2/11 STPNOC’s answer opposing amended petition to intervene ML111530425

6/13/11 Press Release-11-103: “Licensing Board to Hold Teleconference Oral Argument 

June 27 on South Texas Project Reactor License Renewal Application” 

ML11166A046

6/17/11 5/18/11—Summary of telephone conference call held between the NRC and 

STP, concerning RAI pertaining to the STP LRA—severe accident mitigation 

alternative RAI

ML11143A166

6/17/11 RAI for the review of the STP LRA ML11167A113

6/21/11 Plan for the environmental-related regulatory audit regarding the STP, Units 1 

and 2, LRA Review (TAC Nos. ME4938 and ME4939)

ML11145A064
Appendix E

E-6 

Date Correspondence Description ADAMS No.

6/27/11 Transcript of STPNOC’s oral argument (telephone conference) on 

June 27, 2011, pages 1–22

ML11182B033

7/5/11 STP, Units 1 and 2, response to RAI for the review of the LRA ML11193A074

7/5/11 STP, Units 1 and 2, response to RAI for the STP LRA ML11193A016

7/18/11 Audit report regarding STP LRA—cultural resource ML11173A304

7/27/11 License renewal environmental review for STP, Units 1 and 2 (open 

meeting/records request, CPGCD) 

ML11217A017

7/28/11 Memorandum revised (notice pursuant to 10 CFR § 2.309(i)) ML11210B458

8/4/11 RAI for the review of the STP LRA (TAC Nos. ME4938 and ME5122) ML11201A062

8/4/11 Summary of site audit related to the review of the LRA for STP, Units 1 and 2 ML11196A005

8/18/11 RAI for the review of the STP LRA (TAC Nos. ME4938 and ME512) ML11214A207

8/22/11 Comment (63) of Sandra Horris, on behalf of Coastal Plains Groundwater 

Conservation District, on relicensing of STP, Units 1 and 2 (NRC-2010-0375) 

ML11249A042

8/23/11 STP, Units 1 and 2, response to RAI for LRA ML11250A067

8/23/11 Summary of telephone conference call held on July 28, 2011, between the NRC 

and STPNOC, concerning RAI pertaining to the STP LRA

ML11216A263

8/26/11 Memorandum and order (ruling on petition for leave to intervene and request for 

hearing)

ML11238A160

8/31/11 Documents to support review of the STP LRA, list of transmitted documents 

including copy of each document, and enclosure to NOC-AE-11002720

ML11256A057

8/31/11 Documents to support review of the STP LRA, WR–11, “A Summary of Historic 

and Current (past 5 years) Total Dissolved Solids Data for Groundwater 

Produced by STP Production Wells from the Deep Chicot Aquifer”

ML11256A059

8/31/11 Documents to support review of the STP LRA, WR–5, TCEQ ID 

No. 1610103/1610051, “Operation Of Public Potable Water System” 

ML11256A058

8/31/11 STP, Units 1 and 2, transmittal of documents to support review of the STP LRA ML11256A056

9/1/11 RAI for the review of the STP LRA ML112360114

9/6/11 STP, Units 1 and 2, response to RAI for the LRA ML11255A211

9/12/11 STP, Units 1 and 2, response to RAI for the LRA ML11259A014

9/12/11 STP, Units 1 and 2, transmittal of document to support review of the LRA ML11259A031

9/13/11 9/13/11—NRR e-mail capture, STP license renewal, State Historic Preservation 

Office meeting

ML11259A029

9/22/11 STP, Units 1 and 2, response to RAIs for LRA (TAC Nos. ME4938 and ME5122) ML11270A060

9/28/11 RAIs for the review of the STP LRA (TAC Nos. ME4938 And ME5122) ML11269A002

10/18/11 STP, Units 1 and 2, response to RAIs for LRA (TAC Nos. ME4938 and ME5122) ML11298A085

10/26/11 STP, Units 1 and 2, contact information change, LRA (TAC Nos. ME4936 and 

ME4937)

ML11305A075

10/26/11 STP, Units 1 and 2, correction to NRC distribution list ML11307A371

11/17/11 STP, Units 1 and 2, license renewal environmental review (Kickapoo Traditional 

Council)

ML11269A011
Appendix E

E-7 

Date Correspondence Description ADAMS No.

11/17/11 STP, Units 1 and 2, license renewal environmental review (Tonkawa Tribe of 

Oklahoma)

ML11269A015

11/17/11 STP, Units 1 and 2, clarification to response to RAI for LRA (TAC Nos. ME4938 

and ME5122)

ML11333A094

11/29/11 11/1/11—Summary of telephone conference call between the NRC and 

STPNOC concerning RAIs pertaining to the STP LRA

ML11307A381

11/29/11 STP, Units 1 and 2, license renewal environmental review ( Tap PilamCoahuiltecan Nation)ML11269A112

1/4/12 12/15/11—Summary of telephone conference call between NRC and STPNOC

concerning RAI pertaining to the STP LRA

ML11350A222

1/10/12 STP, Units 1 and 2, clarification of Information in support of the review of the 

LRA

ML12011A188

1/19/12 STP, Units 1 and 2, license renewal environmental review ML11269A063

2/14/12 1/31/12—Summary of telephone conference call held between the NRC and 

STPNOC concerning RAIs pertaining to the STP LRA

ML12033A134

2/16/2012 STP, Units 1 and 2, clarification to response to RAI for LRA (TAC Nos. ME4938 

and ME5122)

ML12053A259

2/29/2012 RAI for the Review of the STP LRA (TAC Nos. ME4938 And ME5122) ML12017A128

2/29/2012 1/7/12—Summary of telephone conference call between the NRC and STPNOC 

concerning RAIs pertaining to the STP

ML12047A285

3/12/2012 STP, Units 1 and 2, response to RAIs for LRA (TAC Nos. ME4938 and ME5122) ML12079A014

4/17/2012 STP, Units 1 and 2, renewal of the Wastewater Discharge Permit ML12114A198

5/8/2012 NEPA consultation—Waterborne outbreak ML12128A061

5/18/2012 Environmental Permit Updated Status ML12142A002

APPENDIX F 

NRC STAFF EVALUATION OF SEVERE ACCIDENT MITIGATION 

ALTERNATIVES

F-1 

1 NRC STAFF EVALUATION OF SEVERE ACCIDENT MITIGATION 

2 ALTERNATIVES

3 F.1 Introduction

4 South Texas Project Nuclear Operating Company (STPNOC) submitted an assessment of 

5 severe accident mitigation alternatives (SAMAs) for the South Texas Project, Units 1 and 2,

6 (STP) as part of its Environmental Report (ER) (STPNOC 2010). This assessment was based

7 on the most recent STP probabilistic risk assessment (PRA) available at that time, a 

8 plant-specific offsite consequence analysis performed using the MELCOR Accident 

9 Consequence Code System 2 (MACCS2) computer code, and insights from the STP individual 

10 plant examination (IPE) and individual plant examination of external events (IPEEE) 

11 (HL&P 1992). In identifying and evaluating potential SAMAs, STPNOC considered SAMAs that 

12 addressed the major contributors to core damage frequency (CDF) and population dose at STP, 

13 as well as SAMA candidates found to be potentially cost beneficial in six other license renewal 

14 applications (LRAs). STPNOC initially identified a list of 21 potential SAMAs. This list was 

15 reduced to five unique SAMA candidates by eliminating SAMAs that are not applicable to STP 

16 for one or more of the following reasons:

17 • The SAMA has design differences at STP. 

18 • The SAMAs have already been implemented at STP. 

19 • The SAMA has estimated implementation costs that would exceed the dollar 

20 value associated with eliminating the severe accident risk at STP. 

21 STPNOC assessed the costs and benefits associated with each of the potential SAMAs and 

22 concluded in the ER that none of the candidate SAMAs evaluated are potentially cost beneficial.

23 As a result of the review of the SAMA assessment, the U.S. Nuclear Regulatory Commission 

24 (NRC) staff (the staff) issued requests for additional information (RAIs) to STPNOC by letters 

25 dated May 31, 2011 (NRC 2011a), and September 1, 2011 (NRC 2011b), and in conference 

26 calls for clarification on July 28, 2011 (NRC 2011c), and January 31, 2012 (NRC 2012). Key 

27 questions concerned the following: 

28 • the historical development of the Level 1 and Level 2 PRA and model 

29 changes that most impacted CDF, 

30 • changes to STP design and operation since the version of the PRA used for 

31 the SAMA analysis (referred to as the STP_REV6 model, dated 2009), 

32 • differences between STP, Units 1 and 2, designs or operation and 

33 identification of shared systems, 

34 • the impact of open items and issues from the peer review of the PRA human 

35 reliability analysis (HRA), 

36 • the process used to map Level 1 results into the Level 2 analysis and to 

37 group containment event tree (CET) end states into release categories, 

38 • the selection of representative analysis cases, 

39 • population assumptions used in the Level 3 analysis, 

40 • the uncertainty analysis, 
Appendix F

F-2 

1 • the impact of new information on fire- and seismic-initiated sequences, and

2 • further information on the cost-benefit analysis of several specific candidate 

3 SAMAs and low cost alternatives. 

4 STPNOC submitted additional information by letters dated July 5, 2011 (STPNOC 2011a), 

5 August 23, 2011 (STPNOC 2011b), January 19, 2012 (STPNOC 2012a), and 

6 February 16, 2012 (STPNOC 2012b). In these responses to the RAIs, STPNOC provided: 

7 • a listing of the PRA model changes that had the most impact on CDF, 

8 • identification of design and operation changes since the freeze date and their 

9 impact on PRA results, 

10 • identification of design differences between units as well as shared systems, 

11 • identification and an assessment of the impact of open items and issues from 

12 the PRA reviews, 

13 • a discussion of the process for binning the source term release categories 

14 into release category groups, 

15 • clarification of the bases for selecting representative analysis cases for each 

16 release category group, 

17 • a discussion of the uncertainty analysis, 

18 • further details on the external events PRA models including the impact of new 

19 information on fire and seismic sequences, and 

20 • additional information regarding several specific SAMAs. 

21 STPNOC’s responses addressed the staff’s concerns and did not result in the identification of 

22 any potentially cost-beneficial SAMAs.

23 An assessment of the SAMAs for STP is presented in Sections F.2 through F.6.

24 F.2 Estimate of Risk for STP

25 STPNOC’s estimates of offsite risk at STP are summarized in Section F.2.1. The summary is 

26 followed by the staff’s review of STPNOC’s risk estimates in Section F.2.2.

27 F.2.1 STPNOC’s Risk Estimates

28 Two distinct analyses are combined to form the basis for the risk estimates used in the SAMA 

29 analysis. The first is the STP Level 1 and Level 2 PRA model, which reflects (a) the plant 

30 design configuration as of December 31, 2007, and (b) the plant data from January 1, 1998, 

31 through December 31, 2007, for component failure and equipment unavailability data

32 (STPNOC 2010). 

33 The second is a supplemental analysis of offsite consequences and economic impacts 

34 (essentially a Level 3 PRA model) developed specifically for the SAMA analysis. The SAMA 

35 analysis is based on the most recent STP Level 1 and Level 2 PRA model available at the time 

36 of the ER, referred to as the STP_REV6 model. The scope of the Level 1 model includes 

37 internal and external initiating events.

The STP CDF is approximately 6.4×10-6 38 per year for both internal and external events, as 

39 determined from quantification of the Level 1 PRA model. The CDF is based on the risk 
Appendix F

F-3 

1 assessment for internally initiated events, which includes internal flooding, and external events, 

2 which includes fire, seismic, external flooding, and tornado events. The internal events CDF is 

approximately 3.9×10-6 per year. The external events CDF is approximately 2.5×10-6 3 per year. 

The external events CDF includes contributions of approximately 1.0×10-6 4 per year due to fire 

events, 7.3×10-8 per year due to seismic events, and 1.4×10-6 5 per year due to other external 

6 events (STPNOC 2010). When determined from the sum of the CET sequences, or Level 2 

PRA model, the CDF is approximately 6.2×10-6 7 per year for both internal and external events. 

The 6.2x10-6 8 is used as the baseline CDF in the SAMA evaluations (STPNOC 2010).

9 Note that the above results, and those given in Tables F–1 through F–5, are based upon the 

10 STP model of record (STP_REV6) as presented in the ER (STPNOC 2010) and do not include 

11 STPNOC’s responses to RAIs. The RAIs consider the impact of new industry information 

12 concerning internal fire and seismic initiated events. The results relating to these RAIs are 

13 discussed in Sections F.2.2 and F.6.2.

14 The breakdown of CDF by initiating event is provided in Table F–1, Table F–2, Table F–3, and

15 Table F–4 for internal, fire, seismic, and other external events, respectively (STPNOC 2011a). 

16 Table F–1 shows how internal events contribute about 61 percent of the total CDF. The largest 

17 contributors to the internal event CDF are two loss of offsite power (LOOP) events, “Loss of All 

18 Offsite Power” and “Loss of 345kV Offsite Power,” which contribute 15 percent and 10 percent, 

19 respectively, to the total CDF. 

20 Table F–2 shows how fire events make up the next largest contributor with about 16 percent

21 contribution to the total CDF. “Fire Zone 047 Scenario X” and “Fire Zone 071 Scenario X” are 

22 the largest contributors with 6 percent and 3 percent contribution, respectively, to the total CDF. 

23 Table F–3 shows how seismic events make up a small contribution of about one percent to the 

24 total STP CDF. Seismic events with 0.4 g acceleration and 0.6 g acceleration are the largest 

25 contributors to the seismic event CDF, contributing 0.6 percent and 0.3 percent, respectively.

26 Table F–4 shows how other external events (excluding fire and seismic) make up the next 

27 largest contributor, adding up to about 22 percent of the total CDF. “Tornado Induced Failure of 

28 Switchyard and Essential Cooling Pond (ECP)” and “Essential Cooling Water (ECW) Failure 

29 due to Breach of Main Cooling Reservoir (MCR)” are the largest contributors, with 17 percent 

30 and 5 percent contribution, respectively, to the total CDF.

31 The STP Level 2 PRA model that forms the basis for the SAMA evaluation is an updated 

32 version of the IPE Level 2 model with the latest update incorporated in the 2005 Revision

33 (STP_REV5). The Level 2 model is linked to the Level 1 model by passing the status of all top 

34 events previously evaluated in the Level 1 model. The Level 1 model includes the status of all 

35 systems needed for the Level 2 analysis. The CET, containing only phenomenological events, 

36 is then quantified using these inputs.

37 The CET considers the influence of physical and chemical processes on the integrity of the 

38 containment and on the release of fission products once core damage has occurred. The 

39 quantified CET sequences are binned into a set of end-states or release categories that are 

40 subsequently grouped into four major release groups that provide the input to the Level 3 

41 consequence analysis. The frequency of each major release group was obtained by summing 

42 the frequency of the individual accident progression CET endpoints (or release categories) that 

43 were binned (categorized) into the major release group. Source terms were developed for nine 

44 release categories using the results of Modular Accident Analysis Program (MAAP 4.0.5) 

45 computer code calculations. From these results, source terms were chosen to be 

46 representative of the four major release groups (STPNOC 2011a). The results of this analysis 

47 for STP are provided in Table F.3–2 of ER Attachment F (STPNOC 2010).
Appendix F

F-4 

1 Table F–1. STP Core Damage Frequency for Internal Events

Initiating event (a) CDF

(per year)

% Contribution to 

internal events 

CDF (b, c)

% Contribution to 

total CDF 

Loss of all offsite power 9.6×10-7 25 15

Loss of 345kV offsite power 6.3×10-7 16 10

Steam generator tube rupture (SGTR) 4.4×10-7

 11 7

Excessive loss-of-coolant accident (LOCA) 3.2×10-7 8 5

Steam line break outside containment 2.8×10-7 7 4

Loss of electrical auxiliary building heating, 

ventilation and air conditioning (HVAC)

2.6×10-7 7 4

Turbine trip 1.8×10-7 5 3

Partial loss of main feedwater 1.5×10-7 4 2

Reactor coolant pump (RCP) seal LOCA 1.5×10-7 4 2 

Interfacing system LOCA (ISLOCA) 1.3×10-7 3 2

Loss of DC busses 9.7×10-8 2 2

Small LOCAs 7.5×10-8 2 1

Reactor trip 6.5×10-8 2 1

Other internal events 3.6×10-7 9 6

Total CDF (internal events) 3.9×10-6 100 64

(a) The impact of the sensitivity analysis to updated fire and seismic data on the total CDF is not included in these 

results. Section F.2.2 provides a discussion of these impacts.

(b) Obtained from CDF given in ER Table F.2-1 (STPNOC 2010) divided by the total internal events CDF of 3.89×10-6. (c) May not total to 100 percent due to round off.

2 

3 
Appendix F

F-5 

1 Table F–2. STP Core Damage Frequency for Fire Events

Fire initiator description (a) CDF 

(per year)

% Contribution 

to fire CDF (b, c)

% Contribution 

to total CDF (c)

Fire zone 047 scenario X 4.0×10-7 39 6

Fire zone 071 scenario X 2.1×10-7 21 3

Fire zone 047 scenario B 1.8×10-7 18 3 

Control room fire scenario 18 1.2×10-7 12 2

Fire zone 047 scenario BC 6.4×10-8 6 1

Control room fire scenario 23 2.6×10-8 3 0.4

Fire zone 147 scenario O 1.1×10-8

 1 0.2

Control room fire scenario 10 1.0×10-9

 <1 <0.1

Total CDF (fire events) 1.0×10-6 100 16

(a) The impact of the sensitivity analysis to update fire and seismic data on the total CDF is not included in these 

results. Section F.2.2 provides a discussion of these impacts.

(b) Obtained from CDF given in ER Table F.2-1 (STPNOC 2010) divided by fire events CDF of 1.02×10-6. (c) May not total to 100 percent due to round off.

2 Table F–3. STP Core Damage Frequency for Seismic Events

Initiating event (a) CDF

(per year)

% Contribution to 

seismic CDF (b, c)

% Contribution to 

total CDF (c)

Seismic event, 0.4 g acceleration 4.1×10-8 55 0.6

Seismic event, 0.6 g acceleration 2.1×10-8 28 0.3

Seismic event, 0.2 g acceleration 9.8×10-9 13 0.2

Seismic event, 0.1 g acceleration 2.1×10-9 3 <0.1

Total CDF (seismic events) 7.3×10-8 100 1.1

(a) The impact of the sensitivity analysis to updated fire and seismic data on the total CDF is not included in these 

results. Section F.2.2 provides a discussion of these impacts.

(b) Obtained from CDF given in ER Table F.2-1 (STPNOC 2010) divided by seismic events CDF of 7.31×10-8. (c) May not total to 100 percent due to round off.

3 

4 
Appendix F

F-6 

1 Table F–4. STP Core Damage Frequency for Other External Events

Initiating event (a) CDF

(per year)

% Contribution to 

other external 

events CDF (b, c)

% Contribution to 

total CDF (c)

Tornado induced failure of switchyard and 

ECP

1.1×10-6 79 17

ECW failure due to breach of MCR 2.9×10-7 21 5

External flooding scenarios 2–6 9.5×10-9 <1 0.2

Flood induced LOOP 2.1×10-9 <1 <0.1

Total CDF (other external events) 1.4×10-6 100 22

(a) The impact of the sensitivity analysis to updated fire and seismic data on the total CDF is not included in these 

results. Section F.2.2 provides a discussion of these impacts.

(b) Obtained from CDF given in ER Table F.2-1 (STPNOC 2010) divided by other external events CDF of 1.41×10-6. (c) May not total to 100 percent due to round off.

2 The offsite consequences and economic impact analyses use the MACCS2 code to determine 

3 the offsite risk impacts on the surrounding environment and public. Inputs for these analyses 

4 include plant-specific and site-specific input values for core radionuclide inventory, source term 

5 and release characteristics, site meteorological data, projected population distribution (within a

6 50-mi radius) for the year 2050, emergency response evacuation modeling, and economic data. 

7 The core radionuclide inventory is based on a plant-specific evaluation. The inventory 

8 corresponds to the end-of-cycle values for STP operating at a projected future 4,100 megawatts 

9 thermal (MWt). The current licensed power is 3,835 MWt (STPNOC 2010). The magnitude of 

10 the onsite impacts (in terms of cleanup and decontamination costs and occupational dose) is 

11 based on information provided in NUREG/BR-0184, Regulatory Analysis Technical Evaluation 

12 Handbook (NRC 1997a).

13 In the ER, the applicant estimated the dose risk to the population within 80-km (50-mi) of the 

14 STP site to be approximately 0.0174 person-Sievert (Sv) (1.74 person-roentgen equivalent man 

15 (rem)) per year. The breakdown of the total population dose by containment release mode is 

16 summarized in Table F–5. Large early releases are the dominant contributors (39 percent) to 

17 the population dose risk at STP. Small early releases (with pre-existing small containment 

18 failure) and late releases (with no sprays) are also significant contributors to the population dose 

19 risk. 

20
Appendix F

F-7 

1 Table F–5. Breakdown of Population Dose by Containment Release Mode

Containment release mode

(major release category—RC) (a)

Population dose (personrem (b) per year) % Contribution

RC I—large early releases (<3 hrs) 0.68 39

RC II—small early releases (<3 hrs) 0.59 34

RC III—late releases (>3 hrs) 0.42 24

RC IV—intact containment 0.05 3

Total 1.74 100

(a) The impact of the sensitivity analysis to updated fire and seismic data on the release category frequency is not 

included in these results. Section F.2.2 provides a discussion of these impacts.

(b) One person-rem=0.01 person-Sv. 

2 F.2.2 Review of STPNOC’s Risk Estimates

3 STPNOC’s determination of offsite risk at STP is based on the following three major elements of 

4 analysis:

5 (1) the Level 1 and 2 risk models that form the bases for the 2005 model (STP_REV5) 

6 reviewed by the NRC staff for the approval of the Risk Managed Technical 

7 Specification (RMTS) application, which is an updated version of the 1992 IPE 

8 submittal (HL&P 1992), which incorporated both internal and external events,

9 (2) the modifications to the STP_REV5 model that have been incorporated into the 

10 current STP PRA (STP_REV6), and

11 (3) the MACCS2 analyses performed to translate fission product source terms and 

12 release frequencies from the Level 2 PRA model into offsite consequence measures.

13 Each of these analyses was reviewed to determine the acceptability of STPNOC’s risk 

14 estimates for the SAMA analysis, as summarized below.

15 The first STP Level 1 PRA was completed in 1989 to support a request for revising certain STP 

16 technical specifications. This was subsequently updated and extended to incorporate a Level 2 

17 analysis, as documented in the STP IPE. The 1989 PRA and the IPE incorporated internal fires 

18 and all external events as well as internal event initiators. The internal events and fire events 

19 portions of the 1989 PRA were reviewed extensively as part of the technical specification 

20 change request approval (NRC 1994a). The NRC review of the IPE (NRC 1994b) concluded 

21 that the applicant met the intent of Generic Letter (GL) 88-20 (NRC 1988). Although no 

22 vulnerabilities were identified in the IPE, four improvements were identified. The ER indicated 

23 that all of these improvements have been implemented.

The internal events CDF value from the 1992 IPE (4.3×10-5 24 per year) is near the average of the 

25 values reported for other 4-loop Westinghouse plants. Figure 11.6 of NUREG-1560 

26 (NRC 1997b) shows that the IPE based total internal events CDF for 4-loop Westinghouse 

plants ranges from 3×10-6 per year to 2×10-4 27 per year, with an average CDF for the group of 

6×10-5 28 per year. It is recognized that other plants have updated the values for CDF subsequent 

29 to the IPE submittals to reflect modeling and hardware changes. The internal events CDF result 

for STP used for the SAMA analysis (6.4×10-6 30 per year) is somewhat lower than that for other 

31 plants of similar vintage. This is considered to be reasonable due to the unique design of STP, 

32 which uses three independent emergency core cooling system trains and four auxiliary 
Appendix F

F-8 

1 feedwater pumps as well as having a significant amount of physical separation of the redundant 

2 trains.

3 There have been many revisions to the original STP PRA model. The most relevant are the 

4 IPE, Revision STP_1999 and the subsequent revisions leading up to the current revision used 

5 in the SAMA assessment. A breakdown of the contributors to total CDF and a description of the 

6 changes made to the STP PRA, since the peer reviewed Revision STP_1999, were provided in 

7 response to NRC staff RAIs (STPNOC 2011a, 2011b). These changes are summarized in 

8 Table F–6. The STP_REV6 model reflects the current (as of the date of the ER submittal) STP 

9 configuration and design. In response to an RAI, STPNOC stated that a review of plant design 

10 and operation changes made since the last model update indicates that one modification will 

11 require a PRA model revision. STPNOC does not expect this change to have a significant 

12 effect on the SAMA evaluation (STPNOC 2011a). The staff reviewed the response and agreed 

13 with the applicant that the prospective change to the PRA model would not have a significant 

14 effect on the SAMA evaluation.

15 The STP PRA model is a single unit model rather than a model that incorporates explicit events 

16 in both units. In response to an RAI, STPNOC states that the STP, Units 1 and 2, are designed 

17 to be identical; therefore, the PRA model applies to both STP, Units 1 and 2 (STPNOC 2011a). 

18 However, STPNOC noted that there are two differences between Units 1 and 2 resulting from 

19 the phased implementation of design changes over several different refueling outages. One, 

20 involving load tap changers for engineered safety features transformers, was found to have less 

21 than a 0.5 percent increase in CDF and large early release frequency (LERF). The other, 

22 involving the addition of hand switches for the steam generator (SG) power operated relief 

23 valves in the control room, will exist for only a few months and is expected to result in a 

24 decrease in CDF and LERF (temporary modification to conservatively decrease CDF).
F-9 

Table F–6. STP PRA Historical Summary 1 

PRA version Summary of significant changes 

from prior model 

CDF (a)

(per year) 

Internal 

events

Seismic Fire External 

floods

Flood

MCR

High 

wind

IPE/IPEEE (b)

(1992)

Information from IPE/IPEEE report 

(HL&P 1992)

4.3×10-5 1.4×10-6 1.4×10-6 1.4×10-6 1.4×10-6 1.4×10-6 

STP_1999

(9/2001) 

2002 WOG peer review 8.8×10-6 7.3×10-8 1.4×10-6 1.4×10-8 2.9×10-7 1.1×10-6 

STP_REV4

(9/2003) 

Reviewed by the NRC staff for RMTS 

approval

Incorporated updated plant-specific 

train unavailability data, updated 

initiating events and component failure 

data

Incorporated latest operator error 

modeling and improved LOOP recovery 

modeling

Included safety injection accumulator 

modeling for large and medium LOCAs

Included hot leg recirculation modeling 

for Large LOCA

Removed credit for 150-ton air 

conditioning chillers

Improved modeling of support system 

initiating events

6.6×10-6 7.3×10-8 1.0×10-6 1.4×10-8 2.9×0-7 1.1×10-6 

STP_REV41 (c) Reviewed by the NRC staff for RMTS 

approval

Incorporated operator depressurization 

for small LOCA

Corrected modeling error for long-term 

6.6×10-6 NA NA NA NA NA 
 

F-10

PRA version Summary of significant changes 

from prior model 

CDF (a)

(per year) 

Internal 

events

Seismic Fire External 

floods

Flood

MCR

High 

wind 

response for medium LOCA

Requantified frequency for inadvertent 

opening of one or two pressurizer 

safety valves

Corrected conditional split fractions 

definitions to correct errors in basic 

event importance calculations 

Re-binned several maintenance 

duration data variables to correct input 

problems with RISKMAN version being 

used

Split fault tree basic events containing 

several components to better reflect 

individual component importance.

STP_REV42 Reviewed by the NRC staff for RMTS 

approval

Corrected issues found during 

component risk ranking

NA NA NA NA NA NA 

STP_REV5

(9/2005) 

Reviewed by the NRC staff for RMTS 

approval

Incorporated plant modifications, 

procedure changes and data update 

through 2004

Incorporated modifications to Class IE 

vital AC system and main steam 

isolation valves

Level 2 update including containment 

capability analysis

Updated HRA to use of EPRI HRA 

7.7×10-6 7.3×10-8 9.7×10-7 1.4×10-8 2.9×10-7 1.1×10-6 
 

F-11

PRA version Summary of significant changes 

from prior model 

CDF (a)

(per year) 

Internal 

events

Seismic Fire External 

floods

Flood

MCR

High 

wind 

calculator 

STP_REV51 Added RMTS macros 7.7×10-6 7.3×10-8 9.7×10-7 1.4×10-8 2.9×10-7 1.1×10-6 

STP_REV6

(2009)

Updated equipment reliability data

Updated initiating event data

Updated planned maintenance data

Updated treatment of operator action 

for interfacing system LOCA

3.9×10-6 7.3×10-8 1.0×10-6 1.3×10-8 2.9×10-7 1.1×10-6 

(1/2012) (d) Updated fire analysis for impact of new 

information in NUREG/CR-6850 

(NRC 2005)

Updated seismic analysis for impact of 

2008 USGS seismic hazard 

(USGS 2008)

6.5×10-6 3.0×10-6 2.2×10-6 NA NA NA 

NA—Not available, and value would not impact SAMA Review

(a) All CDF values are point estimate values unless otherwise indicated.

(b) Total external events CDF is given as 3.2 percent of the total or 1.4×10-6 per year.

(c) Based on a response to an NRC staff RAI (STPNOC 2011a), which indicated that the CDF was higher than that for STP_REV4 by 1.2 

(d) Provided for information only. The PRA version is not considered a formal update. The CDF and LERF values were provided in resp

(STPNOC 2012a). All values are based on truncation value of 1×10-14 whereas prior results are based on a truncation value of 1×10-1

high winds are not explicitly provided but are not expected to change from prior values.

 1 
Appendix F

F-12

1 In response to the same RAI, STPNOC indicated that the only shared systems between units 

2 are the common switchyard, MCR, and the ECP (STPNOC 2011a). The NRC staff concludes 

3 that since there are no other shared systems, modeling of the other unit’s features is not 

4 required, and a single unit model is appropriate for the SAMA assessment.

5 The NRC staff noted that the STP PRA results (ER Table F.2–1) do not include any internal 

6 flooding initiated sequences. The NRC staff requested additional information (NRC 2011a), and 

7 STPNOC, in response, indicated that the high degree of separation between redundant 

8 divisions at STP resulted in all internal flooding sequences being screened out in the IPE and 

9 IPEEE (STPNOC 2011a). The NRC staff considered these sequences, as part of the RMTS 

10 review, discussed below. The staff concludes that the internal flood screening remains valid.

11 The NRC staff considered the peer reviews and other assessments performed for the STP PRA 

12 and the potential impact of the review findings on the SAMA evaluation. The most relevant of 

13 these are the 2002 peer review of the STP_1999 model, the STP self-assessment to the 

14 requirements of Regulatory Guide (RG) 1.200, An Approach for Determining the Technical 

15 Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities (NRC 2007a), 

16 and the NRC staff’s review of the STP models REV4, REV41, REV42, and REV5 in support of 

17 STPNOC’s RMTS application. STPNOC stated (STPNOC 2006) that the general assessment 

18 of the peer review was that the STP PRA could effectively be used to support applications 

19 involving risk significance determinations supported by deterministic analyses once the items 

20 noted in the element summaries and fact and observations (F&O) sheets were addressed. All 

21 F&O items were incorporated into STP_REV4, the original basis for the RMTS request, with two 

22 major exceptions. These exceptions were the Level 2 update and reevaluation of the internal 

23 flood modeling. The resolutions of the F&Os associated with the two exceptions were 

24 incorporated into STP_REV5.

25 Revision 5 was performed to ensure that the STP PRA satisfies the requirements of Capability 

26 Category II of the American Society of Mechanical Engineers (ASME) PRA Standard 

27 (ASME 2002, 2003, 2005), as modified by RG 1.200, Appendix B. In response to an NRC RAI 

28 on the RMTS application, STPNOC provided information that described how the STP PRA 

29 meets the ASME criteria (STPNOC 2007). The HRA update, incorporated into Revision 5 of the 

30 PRA, was the subject of a follow-on peer review. As a result of the peer review, STPNOC found 

31 the F&Os from this review to not impact the RMTS application. In addition, these F&Os would 

32 be fully evaluated as part of the Revision 6 PRA (STPNOC 2007). In response to an RAI, 

33 STPNOC identified the content of the 10 Level A and B F&Os and stated that a preliminary 

34 review of the F&Os concluded that their resolution is not expected to have a significant impact 

35 on the STP PRA model or on the SAMA analysis (STPNOC 2011a).

36 The results of the NRC staff’s review of the STP PRA through Revision 5 are documented in a 

37 safety evaluation report (SER) appended to the NRC’s approval of the STP RMTS 

38 (NRC 2007a). The staff reviewed the scope and resolution of the 2002 peer review F&Os and 

39 concluded that the items were properly addressed by the applicant based on the documented 

40 resolutions. Based on the applicant’s assessments and the NRC staff’s reviews, the staff 

41 determined that the STP PRA internal events models met the requirements of RG 1.200, 

42 Revision 1, and were acceptable for the RMTS application.

43 Based on the following information, the NRC staff concludes that the internal events Level 1 

44 PRA model is of sufficient quality to support the SAMA evaluation: 

45 • The STP internal events PRA model has been peer-reviewed and the peer 

46 review findings were all addressed. 
Appendix F

F-13

1 • The model has been reviewed by the NRC staff as part of the RMTS 

2 application approval. 

3 • STPNOC has satisfactorily addressed NRC staff questions regarding the 

4 PRA. 

5 The STP PRA model includes seismic, fire, high winds, floods, and other external initiating 

6 events as well as internal initiating events. The updated external core damage results are 

7 described in ER Section F.2.1 and included in Table F–2 and Table F–3 along with the internal 

8 events results.

9 The STP IPEEE was submitted as part of the IPE in 1992 (HL&P 1992), in response to 

10 Supplement 4 of GL 88-20 (NRC 1991), and was based on the external events portion of the 

11 prior STP PRA submitted and reviewed by the NRC staff to support an STP license amendment 

12 (NRC 1994a). No fundamental weaknesses or vulnerabilities to severe accident risk concerning

13 the external events were identified in the STP IPEEE. In a letter dated December 15, 1998 

14 (NRC 1998), the NRC staff stated that on the basis of the staff’s reviews of the PRA and IPEEE 

15 submittal, the staff concludes that the STP IPEEE process is capable of identifying the most 

16 likely severe accidents and severe accident vulnerabilities. Therefore, the STP IPEEE has met 

17 the intent of Supplement 4 to GL 88-20.

18 The STP IPEEE seismic analysis used a seismic PRA following NRC guidance (NRC 1991) and 

19 used the prior 1988 probabilistic safety assessment or PSA with enhancements recommended 

20 by the NRC guidance. The seismic PRA included a seismic hazard analysis, a fragility analysis, 

21 a plant logic analysis, and quantification of seismic CDF and various plant damage states.

22 The seismic hazard analysis estimated the annual frequency of exceedingly different levels of 

23 ground motion. The STP IPEEE used the Electric Power Research Institute (EPRI) 

24 (EPRI 1989) hazard curves and provided a sensitivity study result using the Lawrence 

25 Livermore National Laboratory (LLNL) (NRC 1989) curve. Four discrete accelerations (0.1 g, 

26 0.2 g, 0.4 g, and 0.6 g) were used to represent the full range of possible accelerations with point 

27 estimate values of the frequency for each acceleration determined from the mean exceedance 

28 frequency from the hazard curves.

29 The seismic fragility for safety-related structures, equipment, and components was determined 

30 from the results of an assessment of the median factor of safety against failure and its statistical 

31 variability under the safe-shutdown earthquake. System and fragility analysts supported the 

32 fragility analysis by plant walk downs. Fragilities for 2 structures and 18 components with 

33 median capacities less than 2.0 g were included in the model. Point estimate fragilities were 

34 then determined for each of the seismic initiating event accelerations evaluated.

35 The plant logic analysis determines the consequences of various structural and component 

36 failures in terms of CDF and release categories. A seismic failure event tree was used to 

37 represent the seismic failure impact of various plant components. The resulting seismic 

38 end-states were then inputted to support front line system trees that also consider non-seismic 

39 unavailabilities.

The seismic CDF resulting from the STP IPEEE was calculated to be 2×10-7 40 per year based on 

the EPRI hazard curve and 2×10-5 41 per year based on the LLNL hazard curve (HL&P 1992; 

NRC 1989). The current CDF value, based on the EPRI hazard curve, is 7×10-8 42 per year. The 

43 STP IPEEE did not identify any vulnerabilities due to seismic events or any potential 

44 improvements to reduce seismic risk.

45 In order to gain a perspective on the impact of the most recent USGS study of seismic hazard 

46 on the STP seismic risk, the NRC staff considered the analysis published for Generic Issue 199 
Appendix F

 

F-14

1 (NRC 2010). This analysis, using a simplified methodology and the 2008 USGS hazard curves 

(USGS 2008), gave a seismic CDF ranging from 9×10-7 to 6×10-6 2 per year for STP depending 

3 on spectral acceleration frequency (the peak ground acceleration or 10, 5, or 1 Hz). These 

4 results range from 8 to 14 times the corresponding seismic CDF value based on the EPRI 

5 hazard curves and used in the SAMA assessment in the ER.

6 In response to an NRC RAI (NRC 2011b), STPNOC updated the results of the seismic risk 

7 analysis to consider recent information for the determination of the seismic hazard frequency 

8 (STPNOC 2012a). The update considered the EPRI, LLNL, and the 2008 USGS hazard curves. 

9 In addition, STPNOC modified the seismic model to include:

10 • an increase in the number of seismic initiators from 4 to 6 to incorporate 

11 higher accelerations than in the original model to be compatible with the 

12 USGS hazard curves which extend to 2.1 g,

13 • the elimination of credit for a sequence specific recovery term that was 

14 non-conservatively applied in the STP_REV6 model, and

15 • an update to seismic fragility curves for many selected components based on 

16 a review of the original calculations and a plant walkdown associated with this 

17 update.

The result of this update yielded a seismic CDF of 3.0×10-6 18 per year based on the 2008 USGS 

19 hazard curves. The NRC staff considers these hazard curves to be the most current data

20 available. The impact of these curves on the SAMA analysis was provided in response to the 

21 NRC RAI and is discussed further in Sections F.3.2 and F.6.2.

22 For SAMA sensitivity consideration, STPNOC has satisfactorily addressed RAIs regarding the 

23 seismic PRA (taking into account the 2008 USGS hazard curves, which are the most current 

24 data available). Hence, the NRC staff concludes that the updated seismic PRA model including 

25 the impact of the 2008 USGS seismic hazard curves provides an acceptable basis for 

26 identifying and evaluating the benefits of SAMAs.

27 The STP IPEEE fire analysis used a fire PRA following NRC guidance (NRC 1991) and 

28 represented an update of the previous 1988 PSA. These analyses involved a two-phase 

29 evaluation process—a spatial interaction analysis and the fire risk assessment. In the spatial 

30 interaction analysis, a large set of internal fire scenarios was identified and screened based on 

31 consideration of initiation frequency, spatial propagation, impact of mitigation, and the impact on 

32 components to plant safety. The resulting fire scenarios considered important were then 

33 analyzed in more detail. The resulting fire induced CDF of the unscreened areas was 

calculated to be 5×10-7 34 per year (NRC 1998).

35 The 1988 STP fire PSA was reviewed by Sandia National Laboratory (SNL). The SNL review 

36 concluded that the fire analysis was acceptable. This review was updated by the NRC staff in 

37 the review of the fire PRA contained in the STP IPEEE with the conclusion that the analysis 

38 examined the significant initiating events and dominant accident sequences for STP 

39 (NRC 1998). The IPE and IPEEE PRA was also used to support STPNOC’s request for 

40 changes in certain technical specifications, which was granted in 1994 (NRC 1994).

41 The fire analysis was subsequently updated in 1994 to address Thermolag® fire barrier 

42 performance. This fire analysis was supported by a comprehensive plant walkdown, in 

43 May 1994, by STP personnel. 

44 As part of the RMTS approval process, the applicant confirmed that all of the high-level 

45 requirements for a fire PRA, given in RG 1.200, Revision 1, are addressed in the STP fire PRA 

46 model and supporting documentation. In response to a staff concern regarding the screening of 
Appendix F

F-15

1 fire sequences for the RMTS application, the applicant determined that there were no screened 

2 sequences that should be included in the PRA model used for the RMTS application 

3 (STPNOC 2007).

4 The NRC staff’s RMTS SER states that, based on STPNOC’s submittal and the staff’s focused 

5 reviews, the STP PRA fire model addresses the technical characteristics and attributes of these 

6 elements, identified in RG 1.200, Revision 1, as they relate to issues that could impact the fire 

7 model’s adequacy for implementation of RMTS. Therefore, the staff finds that the STP PRA fire 

8 model is acceptable for the RMTS application (NRC 2007a).

9 The NRC staff noted that the STP fire PRA may underestimate fire risk since it does not 

10 incorporate the latest guidance in NUREG/CR-6850, EPRI/NRC-RES Fire PRA Methodology for 

11 Nuclear Power Facilities (NRC 2005), and requested that STPNOC assess the impact of this 

12 updated guidance on the SAMA analysis (NRC 2011a). In response to this RAI, STPNOC 

13 provided the results of an assessment of the impact of the information and insights contained in 

14 NUREG/CR-6850 (NRC 2005) concerning fire ignition frequencies, hot short probabilities, and 

15 fire non-suppression probabilities on the eight non-screened fire scenarios included in the 

16 STP_REV6 model (STPNOC 2012a). This assessment yielded a modified fire initiated CDF of 

2.2×10-6 17 per year, which is about 2.2 times higher than that used in the SAMA analysis. The 

18 impact of this modified fire CDF on the SAMA analysis is discussed in Sections F.3.2 and F.6.2.

19 Based on the following information, the NRC staff concludes that the fire PRA model, modified 

20 to address new information and insights contained in NUREG/CR-6850 (NRC 2005), provides 

21 an acceptable basis for identifying and evaluating the benefits of SAMAs: 

22 • the STP fire PRA model has been updated since the IPEEE, 

23 • the updated fire PRA was reviewed by the NRC staff for the RMTS 

24 application, and 

25 • STPNOC has satisfactorily addressed NRC staff RAIs regarding the fire PRA.

26 The STP IPE and IPEEE analysis of high winds, floods, and other external events was based on 

27 the analysis in the 1988 PSA. A wide range of external events was considered; however, no 

28 vulnerabilities were identified in the STP IPEEE due to high winds, floods, and other external 

29 events.

30 For high winds, the STP design is such that critical structures can withstand winds in excess of 

31 360 mph without major damage. The frequency of tornado winds in excess of 360 mph was 

determined to be 8×10-9 32 per year. Since there is considerable safety margin in the design, 

33 failures would not be expected until wind speeds exceed the design value. Tornado missiles 

34 were also considered and the associated risk found to be small.

35 The likelihood of the ECW intake structure being clogged by debris generated by tornados, 

36 hurricanes, or MCR failure were investigated with the dominant contribution being from 

37 tornadoes. The frequency of tornadoes that cause blockage and failure of the switchyard was 

found to be 1.2×10-6 38 per year (initiating frequency), leading to the currently assessed CDF of 

1.1×10-6 39 per year.

40 External flooding of the STP site due to storms, offsite dam breaks, and onsite dam breaks were 

41 considered and evaluated in the STP IPE and IPEEE. Of all the sources affecting plant safety, 

42 the source of greatest importance was found to be the MCR. Many scenarios due to MCR 

43 failure that resulted in impacts to various plant equipment were evaluated with the most 

44 important being MCR failure leading to ECW failure. The current MCR failure frequency is 

3.2×10-7 per year (MCR failure rate), leading to the currently assessed CDF of 2.9×10-7 45 per year.
Appendix F

 

F-16

1 A review of transportation and nearby facility accidents confirmed that there were no severe 

2 accident vulnerabilities from these accidents (transportation and nearby facility external events). 

3 The total contribution to CDF from these other non-fire and non-seismic external events is 

1.4×10-6 4 per year.

5 For the STP RMTS license amendment approval, the NRC staff also reviewed the external 

6 events modeled in the STP PRA and found that the data and assumptions applied were 

7 reasonable and conservative. Based on the applicant’s submittals and the staff reviews, the 

8 staff concluded that the STP PRA external events models complied with the guidance of 

9 RG 1.200, Revision 1, and was acceptable for the RMTS application (NRC 2007b).

10 Given that the STP IPEEE external events PRA model has been reviewed by the NRC staff, 

11 that the current model has been reviewed by the NRC staff as part of the RMTS approval, and 

12 that STPNOC has satisfactorily addressed NRC staff questions regarding the PRA, the NRC 

13 staff concludes that the external events Level 1 PRA model, combined with the results of the 

14 analysis of the impacts of new fire and seismic information, is of sufficient quality to support the 

15 SAMA evaluation.

16 The NRC staff reviewed the general process used by STPNOC to translate the results of the 

17 Level 1 PRA into containment releases, as well as the results of the Level 2 analysis, as 

18 described in the ER and in response to NRC RAIs (STPNOC 2011a). As indicated above, the 

19 Level 2 STP PRA model that forms the basis for the SAMA evaluation is essentially an updated 

20 version of the IPE model.

21 The Level 2 analysis is linked to the Level 1 model by extending the model to include the CET, 

22 which characterizes the accident phenomena. The CET considers the influence of physical and 

23 chemical processes on the integrity of the containment and on the release of fission products 

24 once core damage has occurred. Conditions specifically considered on entry into the CET 

25 include reactor pressure at the time of core damage, steam generator heat removal, availability 

26 of water in the reactor cavity, containment isolation and bypass status, containment spray 

27 operation, containment heat removal, and the initiating event.

28 The STP CET addresses events occurring prior to vessel breach (including the potential for 

29 in-vessel recovery), the phenomena associated with both in-vessel and ex-vessel accident 

30 progression, containment integrity challenges, and the potential for containment failure. The 

31 quantified CET sequences result in 63 possible end-states (or release categories) based on 

32 combinations of reactor coolant system conditions at the time of vessel breach, the availability 

33 of water to cool the core debris, the availability of containment spray, and the mode and timing 

34 of containment failure. These release categories are then combined into the four major release 

35 groups: I—large early release, II—small early release, III—late release, and IV—intact 

36 containment (STPNOC 2011a). The 15 highest frequency release categories that contribute to 

37 the major release groups are described in Table F.3-5 of the ER, Attachment F 

38 (STPNOC 2010).

39 Source terms were developed by the applicant for eight release categories using the results of 

40 MAAP 4.0.5 computer code calculations (STPNOC 2011a). The source term for the intact 

41 release category were estimated from the Wolf Creek SAMA submittal, which is acceptable to 

42 the NRC staff based on both the Wolf Creek and STP plants being Westinghouse 4-loop PWR 

43 plants and the intact containment release category being a small contributor to the total 

44 population dose risk. The results of these analyses for STP are provided in Table F.3-2 of the 

45 ER, Attachment F (STPNOC 2010).

46 Representative source terms for each of the four major release groups were then selected from 

47 the source terms for the nine release categories. This was done by reviewing the relevant 
Appendix F

F-17

1 accident frequencies and release characteristics and selecting the representative accident 

2 sequence and source term that was considered the one that best represented how a change in 

3 major release group frequency would be reflected in terms of consequence. The representative 

4 sequences and source terms selected for the major release groups are identified along with 

5 consequence results in Table F.3-6 of the ER, Attachment F (STPNOC 2010).

6 In the ER, the applicant validated the selection of representative source terms for the major 

7 release groups by recalculating the base case consequences using the set of nine release 

8 categories, for which source terms were available, with their associated frequencies instead of 

9 the four major release groups. As shown in ER Table F.3-8, the total dose-risk consequence 

10 (person-rem per year) is identical to that using the representative source terms for the four 

11 major release groups. The resulting offsite economic consequence risk (dollars per year) is 

12 about 18 percent higher; however, this would only increase the maximum averted cost-risk 

13 (MACR), which is discussed in Section F.6.1, by about 1.5 percent, which the applicant 

14 considered a very minor change (within acceptable SAMA sensitivity consideration by the staff).

15 In an RAI, the NRC staff stated that while the reduced set of four representative sequences 

16 provided essentially the same result as using the full set of nine sequences, this would not 

17 necessarily be true for the cost-benefit analysis of individual SAMAs (NRC 2011a). Since the 

18 source terms for the representative sequences are not necessarily those that would yield the 

19 largest consequence, any SAMA that impacted a release category frequency whose source 

20 term is higher than that for the selected representative sequence would have its benefit 

21 underestimated. In response to the RAI, STPNOC provided a sensitivity analysis using the 

22 most conservative relevant available source term for each of the nine major release categories. 

23 The result was an increase in population dose risk of over 300 percent to 0.0532 person-Sv per 

24 year (5.32 person-rem per year) and a corresponding increase in offsite economic cost risk of 

25 over 400 percent. However, while the results showed that selecting alternate conservative 

26 source terms for the consequence analysis significantly increases the benefit of the SAMAs 

27 evaluated, the conclusions of the SAMA analysis were unchanged (STPNOC 2011a). This is 

28 discussed further in Section F.6.2.

29 The ER notes that some of the MAAP source term release fractions were still increasing based 

30 on calculation times of 24 to 48 hours. A sensitivity case was run with the releases extrapolated 

31 to 72 hrs. The resulting population dose risk increased by 5 percent, and the offsite economic 

32 cost risk increased by 3 percent. 

33 As indicated above, the current STP Level 2 PRA model is an update of the model used in the 

34 IPE. No vulnerabilities were identified in the IPE back-end (i.e., Level 2) analysis. Risk-related 

35 insights and improvements discussed in the IPE submittal were discussed previously. The NRC 

36 staff and contractor review of the IPE Level 2 analysis concluded that the applicant has made 

37 reasonable use of the PSA techniques in performing the back end analysis and that the 

38 techniques employed are capable of identifying severe accident vulnerabilities (NRC 1994b).

39 The LERF model was included in the Westinghouse Owner’s Group (WOG) peer review 

40 discussed previously, and all F&Os have been resolved (STPNOC 2007). The NRC staff’s 

41 review of the RMTS application concluded that all F&Os (including those pertaining to LERF) 

42 were properly addressed. As stated previously, the staff concluded that the internal events PRA 

43 satisfied the guidance of RG 1.200, Revision 1 (NRC 2007b).

44 Based on the NRC staff’s review of the Level 2 methodology, the staff finds that STPNOC has 

45 adequately addressed NRC staff RAIs, that the LERF model has been peer reviewed and all 

46 F&Os resolved, and that the LERF model was recently reviewed and found to be in 

47 conformance with RG 1.200 and the ASME PRA standard. 
Appendix F

 

F-18

1 Based on these findings and the results of the sensitivity analysis, which showed that the 

2 conclusions of the SAMA analysis are not changed by using the full set of nine release 

3 categories, the NRC staff concludes that the Level 2 PRA provides an acceptable basis for 

4 evaluating the benefits associated with various SAMAs.

5 STPNOC used the MACCS2 code and a core inventory from a plant-specific calculation to 

6 determine the offsite consequences of activity release (STPNOC 2010). STPNOC indicated 

7 that the core inventory was generated using ORIGEN2.1 based on a conservative projected 

8 future power of 4,100 MWt for STP. 

9 The NRC staff reviewed the process used by STPNOC to extend the containment performance 

10 (Level 2) portion of the PRA to an assessment of offsite consequences (essentially a Level 3 

11 PRA). This included consideration of the source terms used to characterize fission product 

12 releases for the applicable containment release categories and the major input assumptions 

13 used in the offsite consequence analyses. Plant-specific input to the code includes the source 

14 terms for each source term category and the reactor core radionuclide inventory (both 

15 discussed above), site-specific meteorological data, projected population distribution within an 

16 80-km (50-mi) radius for the year 2050, emergency evacuation modeling, and economic data. 

17 This information is provided in Section F.3 of Attachment F to the ER (STPNOC 2010).

18 All releases were modeled as being from the top of the reactor building. The thermal content of 

19 each of the releases was assumed to be the same as ambient (a non-buoyant plume). 

20 Sensitivity analyses were performed for the elevation and thermal content of the releases. 

21 Decreasing the release height from the top of the reactor building to ground level and 

22 25 percent, 50 percent, and 75 percent of containment height decreased the population dose 

23 risk by 1 to 2 percent and offsite economic cost risk by 2 to 7 percent. Increasing the release 

24 heat to 1 and 10 MW for each plume segment increased the population dose risk by 0 to 

25 3 percent and the offsite economic cost risk by 2 to 7 percent. Building wake effects were also 

26 investigated by increasing and decreasing the wake size by a factor of two. The population 

27 dose risk showed no change, and the offsite economic cost risk either showed no change or 

28 increased by 1 percent. The NRC staff notes that previous SAMA analyses have shown only 

29 minor sensitivities to release height, buoyancy, and building wake effects. Based on the 

30 information provided, the staff concludes that the release parameters used are acceptable for 

31 the purposes of the SAMA evaluation. 

32 STPNOC used site-specific meteorological data for the 2006 calendar year as input to the 

33 MACCS2 code. The development of the meteorological data is discussed in Section F.3.5 of 

34 Attachment F to the ER. The data were collected from the onsite meteorological monitoring 

35 system and the National Weather Service measurements at nearby Palacios Municipal Airport. 

36 Missing meteorological data were first filled in from the onsite backup tower. Gaps in onsite 

37 data were filled in from the hourly data at the Palacios Municipal Airport. Remaining data gaps 

38 were to be filled in by (in order of preference) using corresponding data from the primary tower 

39 60-meter level (taking the relationship between the levels as determined from immediately 

40 preceding hours), interpolation (if the data gap was less than 4 hours), or using data from the 

41 same hour and a nearby day of a previous year. A sensitivity analysis of available data of 

42 record was completed using MACCS2 and the meteorological data for the years 2006 and 2008 

43 and found that data for the year 2006 resulted in the largest dose and economic cost risk and 

44 this was used for the baseline cost-benefit analysis as appropriate. The population dose risk 

45 decreased by 0 to 7 percent and the offsite economic cost decreased by 2 to 11 percent for 

46 years 2008 and 2007, respectively. An additional sensitivity case was completed for rainfall in 

47 the last spatial segment. The base case assumed rainfall at all times. The sensitivity study 

48 allowed the rainfall to follow the onsite meteorology. The resulting population dose risk 

49 decreased by 23 percent, and the offsite economic cost risk decreased by 35 percent. The 
Appendix F

F-19

1 NRC staff notes that previous SAMA analyses results have shown little sensitivity to 

2 year-to-year differences in meteorological data and concludes that the use of the 2006 

3 meteorological data in the SAMA analysis is reasonable.

4 The population distribution used by the applicant as input to the MACCS2 analysis was based 

5 on the year 2000 census data from an updated study for the potential construction of additional 

6 units (STPNOC 2009). County growth rates were applied to obtain the year 2050 population 

7 (Texas State Data Center 2006). In response to an NRC RAI, the applicant stated that the total 

8 population in year 2000 for the SAMA analysis was 1.4 percent higher than the SECPOP2000

9 values presented in Section 2.6.1 of the ER (STPNOC 2011a). This was due to the updated 

10 study using a population based on the construction of additional units that is not included in the 

11 SECPOP2000 data. SECPOP2000 is a computer coded developed for the NRC by Sandia 

12 National Laboratories to calculate the population within 20 and 50 miles of the site. In the RAI 

13 response, STPNOC also provided the year 2050 rosette population distribution. The transient 

14 population within the emergency planning zone (EPZ), was included in the residential population 

15 data for year 2000 and projected to year 2050 (STPNOC 2011a). STPNOC further clarified that 

16 the sector multipliers for the major metropolitan areas within the 50-mi radius included any 

17 expected high growth rates based on the county-weighted population projections 

18 (STPNOC 2011a). The NRC staff considers the methods and assumptions for estimating 

19 population reasonable and acceptable for purposes of the SAMA evaluation.

20 The emergency evacuation model was modeled as a single evacuation zone extending out 

21 16 km (10 mi) from the plant (the EPZ). The applicant assumed that 95 percent of the 

22 population would evacuate. This assumption is conservative relative to the NUREG-1150 study 

23 (NRC 1990), which assumed evacuation of 99.5 percent of the population within the EPZ. The 

24 evacuated population was assumed to move at an average radial speed of approximately 

25 1.34 meters per second (mps) (3.0 mph) with a delayed start time of 60 minutes after 

26 declaration of a general emergency for one-half the population. The evacuation speed was 

27 projected to conditions associated with year 2050 by conservatively assuming that all of the 

28 roads in 2007 transported traffic at their maximum throughput and that no new roads would be 

29 constructed. In response to an NRC RAI, the applicant clarified that the year 2007 evacuation 

30 study population was based on the exponential growth rate from year 2000 to year 2050 

31 (STPNOC 2011a). Transient population was not calculated separately. A general emergency 

32 declaration was assumed to occur when plant conditions degraded to a point where it was 

33 judged that there was a credible risk to the public, based on STP emergency action levels. 

34 Times for declaration of emergency are presented in Table F.3-4 of the ER. A sensitivity study 

35 was completed where the delayed population was increased and decreased by a factor of two. 

36 The population dose risk increased and decreased by 1 percent, respectively, and the offsite 

37 economic cost risk showed no change. Another sensitivity study was performed for the 

38 evacuation speed, where the speed was increased and decreased by a factor of two. The 

39 increased evacuation speed resulted in a population dose risk decrease by 1 percent and no 

40 change in offsite economic cost risk. The decreased evacuation speed resulted in a population 

41 dose risk increase of 2 percent and no change in offsite economic cost risk. The NRC staff 

42 concludes that the evacuation assumptions and analysis are reasonable and acceptable for the 

43 purposes of the SAMA evaluation.

44 SECPOP2000 (NRC 2003) was used to access site-specific agriculture and economic data from 

45 the 1997 National Census of Agriculture for each of the counties surrounding STP to a distance 

46 of 80 km (50 mi). The data file accessed by SECPOP2000 for that information was modified to 

47 correct two errors in the issued version. These errors are generally known as the missing notes 

48 parameter error and the missing county numbers error. In response to an NRC RAI, the 

49 applicant clarified that a third error associated with column formatting of regional economic data 
Appendix F

 

F-20

1 was also corrected (STPNOC 2011a). Region-wide wealth data (i.e., farm wealth and non-farm 

2 wealth) were also based on county-weighted averages for the region within 80 km (50 mi) of the 

3 site using data in the 1997 National Census of Agriculture, as accessed by SECPOP2000. In 

4 addition, generic economic data that applied to the region as a whole, as described in 

5 Section F.3.3 of the ER, were revised from the MACCS2 sample problem input in order to 

6 account for cost escalation since 1986 (the year the input was first specified). An escalation 

7 factor of 1.94, representing cost escalation from 1986 to January 2009, was applied to 

8 parameters describing cost of evacuating and relocating people, land decontamination, and 

9 property condemnation.

10 The NRC staff concludes that the methodology used by STPNOC to estimate the offsite 

11 consequences for STP, combined with the results of the sensitivity analysis associated with the 

12 selection of representative source terms, provides an acceptable basis from which to proceed 

13 with an assessment of risk reduction potential for candidate SAMAs. Accordingly, the NRC staff 

14 based its assessment of offsite risk on the CDF and offsite doses reported by STPNOC. 

15 F.3 Potential Plant Improvements

16 The process for identifying potential plant improvements, an evaluation of that process, and the 

17 improvements evaluated in detail by STPNOC are discussed in this section.

18 F.3.1 Process for Identifying Potential Plant Improvements 

19 STPNOC’s process for identifying potential plant improvements (SAMAs) consisted of the 

20 following elements: 

21 • review of the most significant split fractions from the current, plant-specific 

22 PRA,

23 • review of potential plant improvements identified in the STP IPE and IPEEE,

24 • review of cost-beneficial SAMA candidates identified in LRAs for six other 

25 nuclear power plant sites, and

26 • review of generic SAMA candidates from Nuclear Energy Institute 

27 (NEI) 05-01 (NEI 2005) to identify SAMAs that might address areas of 

28 concern in the STP PRA.

29 Based on this process, an initial set of 21 candidate SAMAs, referred to as Phase I SAMAs, 

30 were identified. In Phase I of the evaluation, STPNOC performed a qualitative screening of the 

31 initial list of SAMAs and eliminated SAMAs from further consideration using the following 

32 criteria: 

33 • The SAMA is not applicable to STP due to design differences. 

34 • The SAMA has already been implemented at STP or would achieve results 

35 that have already been achieved at STP by other means. 

36 • The SAMA has estimated implementation costs that would exceed the dollar 

37 value associated with eliminating all severe accident risk at STP.

38 Based on this screening, 16 SAMAs were eliminated, leaving 5 SAMAs for further evaluation. 

39 The results of the Phase I screening analysis are shown in Table F.5-3 of Attachment F to the 

40 ER. The remaining SAMAs, referred to as Phase II SAMAs, are listed in Table F.6-1 of 

41 Attachment F to the ER (STPNOC 2010). In Phase II, a detailed evaluation was performed for 

42 each of the five remaining SAMA candidates, as discussed in Sections F.4 and F.6.
Appendix F

F-21

1 F.3.2 Review of STPNOC’s Process 

2 STPNOC’s efforts to identify potential SAMAs included explicit consideration of potential SAMAs 

3 for both internal and external events since the STP PRA incorporates all initiating events 

4 including internal, fire, seismic, high winds, and floods. The initial list of SAMAs generally 

5 addressed the hardware considered to be important to CDF and release category frequency 

6 from risk reduction worth (RRW) perspectives at STP and included selected SAMAs from prior 

7 SAMA analyses for other plants.

8 STPNOC provided a tabular listing of the Level 1 PRA split fractions sorted according to their 

9 RRW (STPNOC 2010). SAMAs impacting these split fractions would have the greatest potential 

10 for reducing risk. STPNOC initially identified a RRW cutoff of 1.24, which corresponds to about 

11 a 24 percent change in CDF given 100-percent reliability of the SAMA. This equates to a 

12 benefit of approximately $50,000 for a single unit or $100,000 for both units. This is stated to be 

13 the minimum implementation cost associated with a procedure change. The applicant indicated 

14 that, at this cutoff, only two split fractions would need to be assessed for potential SAMAs. 

15 Since this would only provide limited insights into potential SAMAs, STPNOC extended the 

16 Level 1 importance review to include the top 40 split fractions, which corresponds to a RRW 

17 of 1.022. This is the equivalent of a two-unit benefit of approximately $11,000. All split fractions 

18 in the Level 1 listing were reviewed to identify potential SAMAs and all were addressed by one 

19 or more SAMAs (STPNOC 2010).

20 STPNOC also provided and reviewed the top 40 Level 2 PRA split fractions, corresponding to a 

21 RRW of 1.027, for the release categories contributing over 97 percent of the population 

22 dose-risk and over 99 percent of the offsite economic cost risk. Major release categories I 

23 (large-early), II (small early), and III (late) were included in this assessment. The Level 2 split 

24 fractions for release Category IV (containment intact) were not included in the review to prevent 

25 split fractions unimportant to dose and cost risk from biasing the importance listing. All split 

26 fractions in the Level 2 listing were reviewed to identify potential SAMAs, and all were 

27 addressed by one or more SAMAs (STPNOC 2010).

28 As a result of the review of the Level 1 and Level 2 split fractions, 15 SAMAs were identified. 

29 The applicant reviewed the cost-beneficial Phase II SAMAs from prior SAMA analyses for five 

30 Westinghouse PWR sites and one General Electric BWR site. The applicant’s review identified 

31 six additional SAMAs. It was determined that the other Phase II SAMAs reviewed were already 

32 represented by a SAMA identified from the importance list reviews, have low potential for risk 

33 reduction at STP (i.e., do not address split fractions on the importance lists), or were not 

34 applicable to STP.

35 The NRC staff noted that three SAMAs that were found to be cost beneficial at Prairie Island, 

36 were not addressed by STPNOC. Similarly, three SAMAs were found to be cost beneficial at 

37 Indian Point, were not addressed by STPNOC (NRC 2011a). STPNOC responded to an RAI 

38 indicating that the SAMAs in question had either (a) been implemented at STP or (b) the cost of 

39 implementing at STP exceeded the STP MACR (STPNOC 2011a), which justifies the screening 

40 of the SAMAs. The staff agrees with this assessment.

41 Wolf Creek SAMA 13, “provide an alternate fuel oil tank with gravity feed capability,” was 

42 considered already implemented at STP by an existing capability that requires a pump. The 

43 NRC staff noted that this has less capability than a gravity system and asked STPNOC to 

44 further justify the screening of this SAMA. In response to the RAI, STPNOC provided additional 

45 information on fuel oil storage at STP. The current STP fuel oil transfer system uses a gravity 

46 feed line between the fuel oil storage tank and the standby diesel generator (SBDG). Each 

47 SBDG is supplied from its own dedicated storage tank with a 7-day fuel oil supply. The system 
Appendix F

 

F-22

1 described in the disposition of this SAMA is necessary only to refill these dedicated fuel oil 

2 storage tanks (STPNOC 2011a).

3 SAMA 16, “provide a portable engine driven instrument air compressor,” was identified from a 

4 review of industry cost-beneficial SAMAs and was screened out on the basis of having an 

5 excessive cost. The basis for this SAMA was Prairie Island SAMA 22, which used nitrogen 

6 bottles rather than a portable air compressor. In response to a staff RAI to consider this lower 

7 cost alternative, the applicant indicated that loss of instrument air was not identified as a 

8 significant contributor to STP risk (STPNOC 2011a). There is only one instrument air split 

9 fraction with a RRW greater than 1.000. Its RRW of 1.016 corresponds to an averted cost-risk 

10 of $8,100, which would not result in a cost-beneficial SAMA using nitrogen bottles even at the 

11 95th percentile CDF.

12 STPNOC considered the potential plant improvements described in the STP IPE (HL&P 1992), 

13 which included both internal and external events, in the identification of plant-specific candidate 

14 SAMAs. As a result of the review of the IPE, four improvements were identified and are listed in 

15 Section F.5.1.4 of Attachment F of the ER. The review of the IPE did not lead to any additional 

16 SAMA candidates since the four improvements identified in the IPE have already been 

17 implemented at STP (STPNOC 2010).

18 The applicant also considered the potential for cost-beneficial SAMAs that address the external 

19 event contributors screened out in the IPE and IPEEE because of “low risk.” For each of the 

20 screened initiator types, a potential averted cost-risk (PACR) was determined based on an 

21 estimate of the event occurrence frequency and assuming that the PACR is proportional to this 

22 frequency compared to the CDF. The PACR for each of the seven screened event types is 

23 given in Section F.5.1.5 of the ER. All are less than the minimum implementation cost for the 

24 site of $100,000 associated with a procedure change. This assessment includes internal floods, 

25 which were screened out in the IPE and IPEEE. In response to an NRC RAI, the applicant 

26 indicated that a review of the internal flood screening was performed in support of the RMTS 

27 license amendment with the conclusion that the earlier screening remained valid 

28 (STPNOC 2011a).

29 In response to an NRC RAI, the applicant clarified that the generic list of industry-based SAMA 

30 candidates provided in NEI 05-01 (NEI 2005) was used as an idea source to generate SAMAs 

31 for the important contributors identified from the STP PRA (STPNOC 2011a).

32 As discussed in Section F.2.2, in response to an NRC RAI, STPNOC provided an assessment 

33 of the impact of updated information concerning fire and seismic risks on the overall STP risk. 

34 The postulated fire and seismic changes affect the risk profile and increase the maximum 

35 possible benefit if all risks were eliminated. Because of these changes, the importance analysis 

36 review for the identification of candidate SAMAs and the screening of potential SAMAs was 

37 redone. This reassessment is documented in Tables 8, 9 and 10 of the January 19, 2012, 

38 submittal (STPNOC 2012a). One additional SAMA (SAMA 1a—install a “seismic safe” system) 

39 was identified. This SAMA is similar to SAMA 1 and includes earthquake resistant heat removal 

40 systems that could operate in the event of a seismically induced station blackout (SBO). This 

41 SAMA was screened as having an excessive cost.

42 Based on this information, the NRC staff concludes that the set of SAMAs evaluated in the ER, 

43 together with those identified in response to NRC staff RAIs, addresses the major contributors 

44 to both internal and external event CDF.

45 The NRC staff questioned the applicant about potentially lower cost alternatives to some of the 

46 SAMAs evaluated (NRC 2011a, 2012a), including:
Appendix F

F-23

1 • alternate SAMA(s) for sequences that are mitigated by SAMA 1 but do not 

2 need tornado protection; 

3 • use of the Technical Support Center (TSC) diesel generator (DG) to both 

4 supply the positive displacement pump (PDP) and support auxiliary feedwater 

5 (AFW) operation; 

6 • installing an alternate intake structure for the ECW either in the ECP or the 

7 MCR that would minimize the likelihood of debris preventing ECW cooling or 

8 using temporary and portable pumps with a movable suction that could 

9 provide water to the ECW system; and

10 • strengthening the ECW pump seismic restraints, which was identified as 

11 limiting in the fragility update, in lieu of installing the complex “seismic safe”

12 system (STPNOC 2012a).

13 In response to the RAIs, the applicant addressed the suggested lower cost alternatives and 

14 determined that they were either not feasible or were not cost beneficial 

15 (STPNOC 2011a, 2012b). This is discussed further in Section F.6.2.

16 The NRC staff notes that the set of SAMAs submitted is not all-inclusive since additional, 

17 possibly even less expensive, design alternatives can always be postulated. However, the NRC 

18 staff concludes that the benefits of any additional modifications are unlikely to exceed the 

19 benefits of the modifications evaluated and that the alternative improvements would be unlikely

20 to cost less than the least expensive alternatives evaluated when the subsidiary costs 

21 associated with maintenance, procedures, and training are considered.

22 The NRC staff concludes that STPNOC used a systematic and comprehensive process for

23 identifying potential plant improvements for STP, and the set of SAMAs evaluated in the ER, 

24 together with those evaluated in response to NRC staff inquiries, is reasonably comprehensive 

25 and, therefore, acceptable. This search included reviewing insights from the STP plant-specific 

26 risk studies that included internal initiating events as well as fire, seismic, and other external 

27 initiated events, and reviewing plant improvements considered in previous SAMA analyses. 

28 F.4 Risk Reduction Potential of Plant Improvements

29 In the ER, the applicant evaluated the risk-reduction potential of the five SAMAs that were not 

30 screened out in the Phase I analysis and retained for the Phase II evaluation. The SAMA 

31 evaluations were performed using realistic assumptions with some conservatism.

32 STPNOC used model re-quantification to determine the potential benefits for each SAMA. The 

33 CDF, population dose, and offsite economic cost reductions were estimated using the STP 

34 STP_REV6 PRA model. The changes made to the model to quantify the impact of SAMAs are 

35 detailed in Section F.6 of Attachment F to the ER (STPNOC 2010). Table F–7 lists the 

36 assumptions considered to estimate the risk reduction for each of the evaluated SAMAs, the 

37 estimated risk reduction in terms of percent reduction in CDF and population dose, and the 

38 estimated total benefit (present value) of the averted risk. The estimated benefits reported in 

39 Table F–7 reflect the combined benefit in both internal and external events. The determination 

40 of the benefits for the various SAMAs is further discussed in Section F.6.

41 The impact of SAMA 10, “enhance procedures to ensure the SGs are filled or maintained filled 

42 in SGTR events to scrub fission products,” was modeled by reassigning the SGTR CDF 

contribution for Release Categories I (7.48x10-9 per year) and III (1.35x10-7 43 per year) to Release 

44 Categories II and IV, respectively. In response to an NRC RAI regarding the source of these 

45 values, the applicant indicated that because SAMA 10 is dependent on the availability of 
Appendix F

 

F-24

1 secondary side makeup, only a fraction of SGTR scenarios are relevant to the SAMA 10 

2 evaluation. The relevant frequencies were obtained from an examination of the PRA model’s 

3 results (STPNOC 2011a).

4 The NRC staff noted that the evaluation of SAMA 12, “enhance procedures to prevent clearing 

5 of RCS cold leg water seals,” did not consider the condition in which non-condensable gases 

6 such as hydrogen are present since this condition is not modeled in the PRA. Additionally, the 

7 staff noted that SBO sequences were excluded in the modeling of this SAMA because AC

8 power is needed to start an RCP. The staff asked STPNOC to assess whether these potential 

9 non-conservatisms impact the SAMA analysis (NRC 2011a). In response to the RAI, the 

10 applicant clarified that the scenario leading to hydrogen gas generation condition is represented 

11 conservatively in the induced SGTR event scenarios. The sequences for the scenarios are 

12 included in the assessment of SAMA 12 (STPNOC 2011a). The applicant further clarified that 

13 excluding the SBO sequences is appropriate because: 

14 (a) Induced SGTR is not an issue for SBO scenarios in which offsite power is recovered 

15 in time to prevent core damage. 

16 (b) Plant procedures do not instruct the operators to start the RCPs for SBO scenarios in 

17 which offsite power is restored only after core damage.

18 For these reasons, the applicant concluded that the evaluation of SAMA 12 is not 

19 underestimated.

20 The NRC staff has reviewed STPNOC’s bases for calculating the risk reduction for the various 

21 plant improvements and concludes, with the above clarifications, that the rationale and 

22 assumptions for estimating risk reduction are reasonable and generally conservative (i.e., the 

23 estimated risk reduction is higher than what would actually be realized). Accordingly, the NRC 

24 staff based its estimates of averted risk for the various SAMAs on STPNOC’s risk reduction 

25 estimates.

26 F.5 Cost Impacts of Candidate Plant Improvements

27 STPNOC estimated the costs of implementing the 21 Phase I SAMAs through the development 

28 of site-specific cost estimates and use of other applicants’ estimates for similar improvements. 

29 The costs were developed on a site basis (i.e., two units). If the cost estimate was for a single 

30 unit based on other applicants’ estimates for similar improvements, the cost estimate was 

31 multiplied by two to derive the costs on a site basis. The site-specific cost estimates did not 

32 include (a) contingency cost (unexpected implementation obstacles) or (b) the cost of 

33 replacement power during extended outages required to implement the modifications 

34 (STPNOC 2010). This approach is in accordance with NEI 05-01 and conservative. The cost 

35 estimates based on other applicants’ estimates did not account for inflation, which is also 

36 conservative.

37 In response to an NRC RAI regarding the source of the cost estimates, the applicant replied that 

38 the scope and definition of the SAMA were initially developed by the PRA analyst and then 

39 reviewed and modified by the STP design staff to account for any plant-specific issues that 

40 could interfere with or improve the SAMA design. The major cost contributors were then 

41 identified, and their cost magnitudes were estimated by the design engineers (cost estimating is 

42 a normal part of STPNOC’s design engineers’ functions as appropriate) (STPNOC 2011a).

43 The NRC staff reviewed the applicant’s cost estimates, presented in Table F-6.1 of 

44 Attachment F to the ER in response to NRC RAIs (STPNOC 2011a). For certain improvements, 

45 the NRC staff compared the cost estimates to estimates developed elsewhere for similar 
Appendix F

F-25

1 improvements, including estimates developed as part of other applicants’ analyses of SAMAs, 

2 for operating reactors.

3 The NRC staff noted that the estimated cost of $7.6M for SAMA 17a, “install Westinghouse 

4 RCP shutdown seals,” is higher than other estimates for Westinghouse improved seals such as 

5 the estimate by Tennessee Valley Authority for Watts Bar Unit 2 of $1.1M (TVA 2010). In 

6 response to the RAI, STPNOC indicated that the STP RCP seal design is different from that 

7 used at Watts Bar and other Westinghouse plants (STPNOC 2011a). Because of this unique 

8 design, STP would incur an entire new seal design and associated engineering costs while the 

9 other plants would be able to spread the costs over a larger number of units. STPNOC 

10 provided the details of the STP cost estimate, which included engineering, procedure revision, 

11 modified seal housing, new seals, and installation. The NRC staff notes that even with some 

12 cost savings that might be possible, not included in STPNOC’s estimate, the cost is expected to 

13 be well above the Watts Bar estimate and the STP MACR. The NRC staff considers STPNOC’s 

14 justification for the cost of implementing SAMA 17a reasonable.

15 The NRC staff also noted that the estimated cost of $4.5M for SAMA 14, “provide capability to 

16 cross-tie emergency 4 KV divisions on a single unit,” seems high given that an inter-unit 

17 cross-tie is already available. In response to the RAI, the applicant stated that the original intent 

18 of SAMA 14 was to provide the capability to perform the cross-tie between emergency 4 KV AC 

19 buses within a unit rapidly enough to prevent an RCP seal LOCA. The most effective means for 

20 achieving this capability was a direct bus-to-bus connection, which does not currently exist at 

21 STP. An indirect path is, however, available through an emergency transformer using existing 

22 hardware. Using this path would require significant engineering and procedure development 

23 costs due to the potential for creating single failure potential among multiple divisions of 

24 equipment. While the estimated costs for the work associated with this alternative is not cost 

25 beneficial, STPNOC also notes that the available time to prevent RCP seal failure is such that 

26 navigating through the procedures and implementing the cross-tie in time to prevent seal failure 

27 is unlikely (STPNOC 2011a). The NRC staff considers STPNOC’s justification for the cost of 

28 implementing SAMA 14 reasonable.

29 In response to an NRC RAI (STPNOC 2011a), the applicant provided the details of the cost 

30 estimates for two SAMAs: SAMA 3b, “install fire wrap on PDP cables in cable spreading room,” 

31 and SAMA 11, “modify fire protection system to supply containment spray headers.” The 

32 detailed cost estimate for SAMA 11 supports the cost used and the conclusion in the SAMA 

33 analysis (as discussed in the response). For SAMA 3b, the applicant estimated the engineering 

34 portion of the cost to be $250,000 per unit, which appears high to the NRC staff. The staff notes 

35 that this estimated cost may be valid due to the need to identify the PDP cables (as explained 

36 by the applicant). Furthermore, if the engineering costs were reduced by $50,000 per unit, the 

37 resulting total cost of $700,000 ($800K minus 2x$50K) is still well above the benefit reported for 

38 this SAMA (see Table F–7). The NRC staff concludes that, with the above clarifications, the 

39 cost estimates provided by STPNOC are sufficient and appropriate for use in the SAMA 

40 evaluation.
F-26

Table F–7. SAMA Cost-Benefit Screening Analysis for STP 1 

SAMA (a) Assumptions

% Risk reduction Total ben

CDF Population 

dose

Baseline 

(internal + 

external)

B

u

3b (c)—Install fire wrap on PDP cables 

in cable spreading room

Eliminate failure of the PDP due to a fire in 

the cable spreading room

<1 <1 3K 7

4—Develop procedures to isolate 

CCW inside containment

eliminate failure of the operator action to 

isolate CCW

2 10 27K 7

10—Enhance procedures to ensure 

the SGs are filled or maintain filled in 

SGTR events to scrub fission products

Reassign a portion of the SGTR CDF 

contribution for the large early release 

category (7.48E-06 per year) and late 

release category (1.35E-07 per year) to 

the small early release category and intact 

containment release category, respectively

0 2 3K 8

12—Enhance procedures to prevent 

clearing of RCS cold leg water seals

Reassign the induced SGTR CDF 

contribution (2.4E-09 per year) for 

sequences in which offsite power is 

available from the large early release 

category to the intact containment release 

category

0 0 <1K <

13—Develop procedures to open 

doors or use portable fans for alternate 

SBDG room cooling or both

Eliminate failure of the operator action to 

provide SBDG room cooling

<1 0 1K 3

15—Develop emergency procedures 

for alternate essential ECWIS room 

cooling

Eliminate failure of the operator action to 

provide ECWIS room cooling

1 2 8K 2

(a) The impact of the sensitivity analysis to updated fire and seismic data is not included in these results. Section F.6.2 provides a discuss

(b) Based on the response to NRC staff RAI 1.d (STPNOC 2011b), the NRC staff increased the baseline benefits by a factor of 2.7 to acco

(c) SAMA 3b retained as a Phase II SAMA based on the results of the uncertainty analysis.
Appendix F

F-27

1 F.6 Cost–Benefit Comparison

2 STPNOC’s cost-benefit analysis and the NRC staff’s review are described in the following 

3 sections.

4 F.6.1 STPNOC’s Evaluation 

5 The methodology used by the applicant was based primarily on NRC’s guidance for performing 

6 cost-benefit analysis (i.e., NUREG/BR-0184 (NRC 1997a)). The guidance involves determining 

7 the net value for each SAMA according to the following formula:

8 Net Value = (APE + AOC + AOE + AOSC) − COE 

9 where: 

10 APE = present value of averted public exposure ($)

11 AOC = present value of averted offsite property damage costs ($)

12 AOE = present value of averted occupational exposure costs ($)

13 AOSC = present value of averted onsite costs ($)

14 COE = cost of enhancement ($)

15 If the net value of a SAMA is negative, the cost of implementing the SAMA is larger than the 

16 benefit associated with the SAMA, and it is not considered cost beneficial. STPNOC’s 

17 derivation of each of the associated costs is summarized below.

18 NUREG/BR-0058 has been revised to reflect the NRC’s policy on discount rates. Revision 4 of 

19 NUREG/BR-0058 states that two sets of estimates should be developed, one at 3 percent and 

20 one at 7 percent (NRC 2004). The applicant provided a base set of results using the 3 percent

21 discount rate and a sensitivity study using the 7 percent discount rate (STPNOC 2010).

23 The APE costs were calculated using the following formula:

22 Averted Public Exposure (APE) Costs

24 APE = Annual reduction in public exposure (Δ person-rem per year)

25 x monetary equivalent of unit dose ($2,000 per person-rem)

26 x present value conversion factor (15.04 based on a 20-year period 

27 with a 3-percent discount rate)

28 As stated in NUREG/BR-0184 (NRC 1997a), it is important to note that the monetary value of 

29 the public health risk after discounting does not represent the expected reduction in public 

30 health risk due to a single accident. Rather, it is the present value of a stream of potential 

31 losses extending over the remaining lifetime, in this case, the renewal period, of the facility. 

32 Thus, it reflects the expected annual loss due to a single accident, the possibility that such an 

33 accident could occur at any time over the renewal period, and the effect of discounting these 

34 potential future losses to present value. For the purposes of initial screening, which assumes 

35 elimination of all severe accidents due to internal and external events, the applicant calculated 

36 an APE of approximately $52,300 for the 20-year license renewal period (STPNOC 2010).

38 The AOCs were calculated using the following formula:

37 Averted Offsite Property Damage Costs (AOC)

39 AOC = Annual CDF reduction

40 x offsite economic costs associated with a severe accident (on a per event 

41 basis) 

42 x present value conversion factor
Appendix F

 

F-28

1 For the purposes of initial screening, which assumes all severe accidents due to internal and 

2 external events are eliminated, the applicant calculated an annual offsite economic risk of about 

3 $1,600 based on the Level 3 risk analysis. This results in a discounted value of approximately 

4 $24,400 for the 20-year license renewal period (STPNOC 2010).

6 The AOE costs were calculated using the following formula:

5 Averted Occupational Exposure (AOE) Costs

7 AOE = Annual CDF reduction

8 x occupational exposure per core damage event

9 x monetary equivalent of unit dose

10 x present value conversion factor

11 The applicant derived the values for averted occupational exposure from information provided in 

12 Section 5.7.3 of the NUREG/BR-0184 (NRC 1997a). Best estimate values provided for 

13 immediate occupational dose (3,300 person-rem) and long-term occupational dose (20,000 

14 person-rem over a 10-year cleanup period) were used. The present value of these doses was 

15 calculated using the equations provided in the handbook in conjunction with a monetary 

16 equivalent of unit dose of $2,000 per person-rem, a real discount rate of 3 percent, and a time 

17 period of 20 years to represent the license renewal period. For the purposes of initial screening, 

18 which assumes all severe accidents due to internal and external events are eliminated, the 

19 applicant calculated an AOE of approximately $4,000 for the 20-year license renewal period 

20 (STPNOC 2010).

22 Averted onsite costs (AOSC) include averted cleanup and decontamination costs and averted 

23 power replacement costs. Repair and refurbishment costs are considered for recoverable 

24 accidents only and not for severe accidents. The applicant derived the values for AOSC based 

25 on information provided in Section 5.7.6 of NUREG/BR-0184 (NRC 1997a).

21 Averted Onsite Costs

26 The applicant divided this cost element into two parts—the onsite cleanup and decontamination 

27 cost, also commonly referred to as averted cleanup and decontamination costs, and the 

28 replacement power cost.

29 Averted cleanup and decontamination costs (ACC) were calculated using the following formula:

30 ACC = Annual CDF reduction

31 x present value of cleanup costs per core damage event

32 x present value conversion factor

33 The total cost of cleanup and decontamination subsequent to a severe accident is estimated in 

the NUREG/BR-0184 (NRC 1997a) to be $1.5x109 34 (undiscounted). This value was converted to 

35 present costs over a 10-year cleanup period and integrated over the term of the proposed 

36 license extension. For the purposes of initial screening, which assumes all severe accidents 

37 due to internal and external events are eliminated, the applicant calculated an ACC of 

38 approximately $124,500 for the 20-year license renewal period (STPNOC 2010).

39 Long-term replacement power costs (RPC) were calculated using the following formula: 

40 RPC = Annual CDF reduction

41 x present value of replacement power for a single event

42 x factor to account for remaining service years for which replacement power 

43 is required
Appendix F

F-29

1 x reactor power scaling factor

2 The applicant based its calculations on the rated STP net electric output of 

3 1,365 megawatt-electric (MWe) per unit and scaled up from the 910 MWe reference plant in 

4 NUREG/BR-0184 (NRC 1997a). Therefore, the applicant applied a power-scaling factor of 

5 1,365/910 (or STP net electric output divided by reference plant output) to determine the 

6 replacement power costs. For the purposes of initial screening, which assumes all severe 

7 accidents due to internal and external events are eliminated, STPNOC calculated an RPC of 

8 approximately $53,000 and an AOSC of approximately $178,000 for the 20-year license 

9 renewal period (STPNOC 2010).

10 Using the above equations, the applicant estimated the total present dollar value equivalent 

11 associated with eliminating severe accidents from internal and external events at STP to be 

12 about $258,200 for a single unit, rounded to $259,000. Because all SAMA costs and benefits 

13 were provided on a site basis, the applicant doubled this value to obtain the two-unit site value 

14 of $518,000. This represents the dollar value associated with eliminating severe accident risks 

15 for all internal and external events at the two STP units (referred to as the maximum averted 

16 cost-risk (MACR)).

18 If the implementation costs for a candidate SAMA exceeded the calculated benefit, the SAMA 

19 was considered not to be cost beneficial. In the baseline analysis contained in the ER (using a 

20 3 percent discount rate), STPNOC identified no potentially cost-beneficial SAMAs. STPNOC 

21 also did not identify any potentially cost-beneficial SAMAs even after consideration of analysis 

22 uncertainties.

17 STPNOC’s Results

23 F.6.2 Review of STPNOC’s Cost-Benefit Evaluation 

24 The cost-benefit analysis performed by STPNOC was based primarily on NUREG/BR-0184 

25 (NRC 1997a) and discount rate guidelines in NUREG/BR-0058 (NRC 2004). The analysis was 

26 executed consistently with this guidance. No SAMAs were determined to be cost beneficial in 

27 STPNOC’s baseline analysis in the ER.

28 The applicant considered the impact that possible increases in benefits from analysis 

29 uncertainties would have on the results of the SAMA assessment. In the ER, STPNOC 

30 presents the results of an uncertainty analysis of the internal and external events CDF for STP, 

31 which indicates that the 95th percentile value is a factor of 1.6 greater than the mean CDF for 

32 STP. The applicant considered whether any additional Phase I SAMAs might be retained for 

33 further analysis if the MACR is increased by a factor of 1.6. One such SAMA was identified—

34 SAMA 3b, “install fire wrap on PDP cables in cable spreading room.” 

35 The applicant also considered the impact on the Phase II analysis if the estimated benefits from 

36 internal and external events were increased by the 1.6 uncertainty factor. The additional 

37 Phase I SAMA—SAMA 3b—was included in this sensitivity analysis. No SAMAs became cost

38 beneficial in STPNOC’s analysis (STPNOC 2010).

In Section F.7.1 of the ER, the total CDF of 6.39×10-6 39 per year is described as being the mean 

40 from the RISKMAN Monte Carlo quantification. In response to the NRC RAI on the uncertainty 

41 analysis, STPNOC provided further information describing how the analysis was performed. 

42 Since the quantification of the complete STP Level 1 PRA results in a large number of 

43 sequences, for which an uncertainty analysis is impractical, a reduced set of sequences is used. 

44 The results of the Monte Carlo analysis were then scaled so that the mean of the distribution 
Appendix F

 

F-30

matched the mean of the CDF point estimates. The total CDF of 6.39×10-6 1 per year is, 

2 therefore, a point estimate (STPNOC 2011a).

3 In response to an NRC RAI (NRC 2011a), STPNOC provided an uncertainty analysis that 

indicated the 95th percentile CDF for the reduced set of sequences used is 1.59×10-5 4 per year 

while the mean CDF and point estimate CDF for these sequences are 8.52×10-6 5 per year and 

5.89×10-6 6 per year, respectively. The uncertainty multiplier was then revised to be the ratio of 

7 the 95th percentile CDF to the point estimate, both for the reduced set of sequences, or 

1.59×10-5 divided by 5.89×10-6 8 or 2.7 (STPNOC 2011b). The applicant considered whether any 

9 additional Phase I SAMAs might be retained for further analysis if the MACR is increased by a 

10 factor of 2.7. No additional SAMAs were identified.

11 The applicant also considered the impact on the Phase II analysis if the estimated benefits from 

12 internal and external events were increased by the 2.7 uncertainty factor. No SAMAs became 

13 cost beneficial in STPNOC’s analysis (STPNOC 2011b).

14 The NRC staff noted that the original 1.6 uncertainty ratio developed for STP appeared to be 

15 low considering the larger uncertainty bands associated with external events. The applicant 

16 responded that, with the exception of seismic initiating events, probability distributions for all 

17 initiating events were included in the Monte Carlo uncertainty analysis and that use of point 

18 estimates for the seismic sequences was considered justified because of the small seismic CDF 

19 contribution (STPNOC 2011a). However, as discussed in Section F.2.2, the seismic CDF may 

20 be considerably larger than that used in the cost-benefit analyses presented in the ER. 

21 Based on the following information, the NRC staff considers the use of the 2.7 uncertainty 

22 multiplier for the SAMA analysis. This is consistent with the guidance provided in NEI 05-01 

23 and acceptable: 

24 • STPNOC’s revised analysis used the higher uncertainty factor of 2.7, which is 

25 generally higher than the 95th percentile uncertainty factor used in other 

26 SAMA analyses. 

27 • STPNOC performed a separate assessment of the impact of the higher 

28 seismic CDF on the SAMA analysis. 

29 • The increased uncertainty in seismic risk would not be expected to impact the 

30 benefit of SAMAs not specifically addressing seismic failures. 

31 STPNOC provided the results of additional sensitivity analyses in the ER, including use of a 

32 7 percent discount rate and variations in MACCS2 input parameters. These analyses did not 

33 identify any additional potentially cost-beneficial SAMAs (STPNOC 2010).

34 As discussed in Section F.2.2, the selection of representative sequences and associated source 

35 terms to be used for the four major release categories could yield non-conservative risk 

36 benefits. In response to an NRC RAI, the applicant provided the results of a sensitivity analysis 

37 that used the most conservative relevant available source term for each of the nine major 

38 release categories (STPNOC 2011a). STPNOC revised the baseline analysis using the 

39 conservative source terms (using a 3 percent discount rate) and identified no potentially 

40 cost-beneficial SAMAs. The NRC staff also increased the revised baseline benefits by a factor 

41 of 2.7 to account for uncertainties and identified no potentially cost-beneficial SAMAs. The 

42 results for the revised baseline and revised baseline with uncertainty are provided in Table F–8. 
Appendix F

F-31

1 Table F–8. SAMA Cost-Benefit Screening Analysis for 

2 STP Using Conservative Source Terms

SAMA

Total benefit ($)

Cost ($)

Conservative 

source terms 

revised baseline 

(internal + 

external)

Conservative 

source terms 

revised baseline 

with 

uncertainty(a)

3b—Install fire wrap on PDP cables in cable 

spreading room

7K 18K 800K

4—Develop procedures to isolate CCW inside 

containment

35K 94K 100K

10—Enhance procedures to ensure the SGs are 

filled or maintain filled in SGTR events to scrub 

fission products

30K 80K 100K

12—Enhance procedures to prevent clearing of 

RCS cold leg water seals

<1K <1K 100K

13—Develop procedures to open doors or use 

portable fans for alternate SBDG room cooling or 

both

4K 10K 100K

15—Develop emergency procedures for alternate 

ECWIS room cooling

14K 38K 100K

(a) Based on the response to NRC RAI 1.d (STPNOC 2011b), the NRC staff increased the revised baseline benefits 

by a factor of 2.7 to account for uncertainties.

3 SAMAs identified primarily on the basis of the internal events analysis could provide benefits in 

4 certain external events, in addition to their benefits in internal events. Since the STP_REV6 

5 PRA model is an integrated internal and external events model, STPNOC’s evaluation 

6 accounted for the potential risk reduction benefits associated with both internal and external 

7 events.

8 As discussed in Section F.2.2, the NRC staff asked STPNOC to assess the impact of the 

9 updated fire and seismic information on the SAMA analysis (NRC 2011a). In this analysis, 

10 STPNOC revised the baseline analysis using the updated fire and seismic information and 

11 increased these revised baseline analyses by 2.7 to account for uncertainties (using a 3 percent

12 discount rate) and identified no potentially cost-beneficial SAMAs. The NRC staff also 

13 increased these revised benefits to account for the conservative source terms and identified no 

14 potentially cost-beneficial SAMAs. The results of these analyses are provided in Table F–9. 

15
Appendix F

 

F-32

 1 

2 Table F–9. SAMA Cost-Benefit Screening Analysis for 

3 STP Using Updated Fire and Seismic Risk Analysis and Conservative Source Terms

SAMA

Total benefit ($)

Cost ($)

Updated fire and 

seismic risk 

assessment 

(internal + 

external) with 

uncertainty(a)

Updated fire and 

seismic risk 

assessment 

(internal + external) 

with uncertainty(a)

and conservative 

source terms(b)

3b—Install fire wrap on PDP cables in cable 

spreading room

18K 44K 800K

4—Develop procedures to isolate CCW inside 

containment

71K 94K 100K

10—Enhance procedures to ensure the SGs are 

filled or maintain filled in SGTR events to scrub 

fission products

8K 84K 100K

12—Enhance procedures to prevent clearing of 

RCS cold leg water seals

3K 4K 100K

13—Develop procedures to open doors or use 

portable fans for alternate SBDG room cooling or 

both

16K 51K 100K

15—Develop emergency procedures for 

alternate ECWIS room cooling

22K 41K 100K

(a) Baseline benefits increased by a factor of 2.7 to account for uncertainties (STPNOC 2012a, 2012b).

(b) The impact of conservative source terms is obtained from the results provided in Table 2-11 of the July 5, 2011, 

submittal (STPNOC 2011a) compared with the results of the original submittal (STPNOC 2010).

4 As indicated in Section F.3.2, the NRC staff asked the applicant to evaluate potentially lower 

5 cost alternatives to the SAMAs considered in the ER (NRC 2011a), as summarized below:

6 • SAMA 1, “involving using a portable AC generator for long term AFW support 

7 and protecting the Technical Support Center (TSC) emergency diesel 

8 generator (EDG) from tornado events,” was identified as a means of 

9 mitigating a large number of important basic events. While the tornado 

10 protection is important for high wind initiated sequences, many other 

11 sequences would be mitigated without the cost of the tornado protection. 

12 STPNOC provided the results of a cost estimate that did not include the costs 

13 associated with the tornado protection. The revised cost of $2.4 million is 

14 much larger than the MACR; hence, such an alternative was determined not 

15 to be cost beneficial (STPNOC 2011a).

16 • An additional alternate to SAMA 1 would be to use the TSC DG to both 

17 supply the PDP and support AFW operation rather than requiring a portable 

18 AC generator. STPNOC provide the results of a cost estimate for this 

19 alternative. The revised cost of $1.9 million remains above the MACR; 
Appendix F

F-33

1 hence, this alternative was determined not to be cost beneficial 

2 (STPNOC 2011a).

3 • The tornado induced failure of the switchyard and emergency cooling pond 

4 could be mitigated by installing an alternate intake structure for the ECW 

5 either in the ECP or the MCR that would minimize the likelihood of debris 

6 preventing ECW cooling or using a temporary and portable pumps with a 

7 movable suction that could provide water to the ECW system. In response to 

8 the RAI, STPNOC provided the results of a cost estimate for a large surface 

9 area debris cage as a less costly alternative to an additional intake structure. 

10 This cost was $828,000, which is approximately equal to the 95th percentile 

11 MACR. The cost for the even less costly portable truck-mounted pump 

12 alternative was given as $350,000. While less than the MACR, this cost is 

13 more than the benefit associated with eliminating the tornado initiated 

14 sequence (17 percent of the total CDF), or $143,000 at the 95th percentile; 

15 hence, this alternative was determined to not be cost beneficial 

16 (STPNOC 2011a).

17 • Strengthening ECW pump seismic restraints was identified as an alternative 

18 to the SAMA 1a “seismic safe” system. While not mitigating all seismically 

19 induce SBOs, it is potentially less costly than the complex “seismic safe” 

20 system. STPNOC assessed the benefit of eliminating the risk to ECW pump 

21 seismic failures using the Fussell-Vesely importance results and found the 

22 benefit to be $54,000 using the 2.7 uncertainty multiplier. However, it is not 

23 cost beneficial because it is less than the minimum SAMA implementation 

24 cost (for procedure changes) of $100,000 (STPNOC 2012b). If adjusted to 

25 incorporate the potential impact of the more conservative source terms, the 

26 NRC staff estimates that the benefit could be somewhat greater 

27 than $100,000. However, based on the expected cost of strengthening the 

28 seismic restraints, which would involve replacing 24 seismic bolts deeply 

29 imbedded in concrete, and that the analysis conservatively assumes all of the 

30 risk would be eliminated by replacing the seismic bolts, the NRC staff 

31 concludes that this alternative is unlikely to be cost beneficial.

32 As indicated in Section F.4, the NRC staff questioned STPNOC on the risk reduction potential 

33 for certain SAMAs (NRC 2011a, 2011b). In response to the RAIs, STPNOC addressed each 

34 SAMA and addressed the staff concerns.

35 The NRC staff concludes that the costs of all of the SAMAs evaluated would be higher than the 

36 associated benefits.

37 F.7 Conclusions

38 STPNOC compiled a list of 21 SAMAs based on a review of the most significant split fractions 

39 from the plant-specific internal and external event PRA, insights from the plant-specific IPE, 

40 cost-beneficial SAMAs from LRAs for other plants, and review of other industry documentation. 

41 An initial qualitative screening removed SAMA candidates that: 

42 • modified features not applicable to STP due to design differences, 

43 • were determined to have already been implemented at STP or would achieve 

44 results that have already been achieved at STP by other means, or 
Appendix F

 

F-34 

1 • have estimated implementation costs that would exceed the dollar value 

2 associated with completely eliminating all severe accident risk at STP. 

3 Based on this screening, 16 SAMAs were eliminated, leaving 5 candidate SAMAs for 

4 evaluation.

5 For the remaining SAMA candidates, a cost-benefit analysis was performed, with the results 

6 shown in Table F–7. The cost-benefit analyses showed that none of the SAMA candidates 

7 were potentially cost beneficial in the baseline analysis. STPNOC performed additional 

8 analyses to evaluate the impact of parameter choices and uncertainties on the results of the 

9 SAMA assessment. In this process, one additional SAMA was identified for detailed 

10 cost-benefit analysis. However, additional analyses did not result in the discovery of any of the 

11 SAMA candidates being potentially cost beneficial.

12 The NRC staff reviewed the STPNOC analysis and concludes that the methods used, and the 

13 implementations of those methods, were sound. The treatment of SAMA benefits and costs 

14 supports the general conclusion that the SAMA evaluations performed by STPNOC are 

15 reasonable and sufficient for the license renewal submittal.

16 The staff concurs with STPNOC’s conclusion that none of the candidate SAMAs are potentially 

17 cost beneficial. This conclusion is based on the generally conservative treatment of costs and 

18 benefits. This conclusion is consistent with the low residual level of risk indicated in the STP 

19 PRA and the fact that STPNOC has already implemented the plant improvements identified 

20 from the IPE and IPEEE. 

21 F.8 References

22 10 CFR Part 50. Code of Federal Regulations, Title 10, Energy, Part 50, “Domestic Licensing of 

23 Production and Utilization Facilities.”

24 10 CFR Part 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental 

25 protection regulations for domestic licensing and related regulatory functions.”

26 10 CFR Part 54. Code of Federal Regulations, Title 10, Energy, Part 54, “Requirements for 

27 Renewal of Operating Licenses for Nuclear Power Plants.”

28 10 CFR Part 100. Code of Federal Regulations, Title 10, Energy, Part 100, “Reactor Site 

29 Criteria.”

30 [ASME] American Society of Mechanical Engineers. 2002. “Standard for Probabilistic Risk 

31 Assessment for Nuclear Power Plant Applications.” ASME RA-S-2002, April 5, 2002.

32 [ASME] American Society of Mechanical Engineers. 2003. “Addenda to ASME RA-S-2002, 

33 Standard for Probabilistic Risk Assessment for Nuclear Power Plant Applications.” ASME 

34 RA-Sa-2003, December 5, 2003.

35 [ASME] American Society of Mechanical Engineers. 2005. “Addenda to ASME RA-S-2002, 

36 Standard for Probabilistic Risk Assessment for Nuclear Power Plant Applications.” ASME 

37 RA-Sb-2005, December 30, 2005.

38 [EPRI] Electric Power Research Institute. 1989. “Probabilistic Seismic Hazard Evaluations at 

39 Nuclear Plant Sites in the Central and Eastern United States; Resolution of the Charleston 

40 Earthquake Issues.” EPRI NP-6395-D, EPRI Project P101-53, Palo Alto, CA. April 1989.

41 [HL&P] Houston Lighting and Power Company. 1992. “South Texas Project Electric 

42 Generating Station Level 2 Probabilistic Safety Assessment and Individual Plant Examination.” 

43 August 1992. ADAMS No. ML0617001702, ML0617001790, ML0617001850.
Appendix F

F-35

1 [NEI] Nuclear Energy Institute. 2005. Severe Accident Mitigation Alternative (SAMA) Analysis 

2 Guidance Document, NEI 05-01 (Rev. A). Washington, D.C. November 2005.

3 [NRC] U.S. Nuclear Regulatory Commission. 1988. Generic Letter 88-20, “Individual Plant 

4 Examination for Severe Accident Vulnerabilities.” November 23, 1988. ADAMS 

5 No. ML031150465

6 [NRC] U.S. Nuclear Regulatory Commission. 1989. Seismic Hazard Characterization of 

7 69 Nuclear Plant Sites East of the Rocky Mountains. Washington DC: NRC. 

8 NUREG/CR-5250, Volume 5. 1989.

9 [NRC] U.S. Nuclear Regulatory Commission. 1990. Severe Accident Risks: An Assessment 

10 for Five U.S. Nuclear Power Plants—Final Summary Report. Washington DC: NRC. 

11 NUREG-1150, Volume 1. 1990.

12 [NRC] U.S. Nuclear Regulatory Commission. 1991. Individual Plant Examination of External 

13 Events (IPEEE) for Severe Accident Vulnerabilities. Washington, DC: NRC. Generic Letter 

14 No. 88-20, Supplement 4. June 28, 1991. ADAMS No. ML031150485

15 [NRC] U.S. Nuclear Regulatory Commission. 1994a. Letter from Suzanne C. Black, Director, to 

16 William T. Cottle, Houston Lighting & Power Company. Subject: “Issuance of Amendment 

17 Nos. 59 and 47 to Facility Operating License Nos. NPF-76 and NPF-80 and Related Relief 

18 Request—South Texas Project, Units 1 and 2 (TAC Nos. M76048 and M76049).” 

19 February 17, 1994. ADAMS No. ML021300134.

20 [NRC] U.S. Nuclear Regulatory Commission. 1994b. Memorandum to: Steven A. Varga 

21 (USNRC-NRR) to M. Wayne Hodges (USNRC-RES), Subject: Review of South Texas Project 

22 Individual Plant Examination (IPE) Submittal—Internal Events. December 1994.

23 [NRC] U.S. Nuclear Regulatory Commission. 1997a. Regulatory Analysis Technical Evaluation 

24 Handbook. Washington, DC: NRC. NUREG/BR-0184. ADAMS No. ML050190193.

25 [NRC] U.S. Nuclear Regulatory Commission (NRC). 1997b. Individual Plant Examination 

26 Program: Perspectives on Reactor Safety and Plant Performance. Washington, DC: NRC. 

27 NUREG-1560. ADAMS No. ML063550244, ML063550228, and ML063470259. 

28 [NRC] U.S. Nuclear Regulatory Commission. 1998. Letter from Thomas W. Alexion, U.S. NRC, 

29 to William T. Cottle, STP Nuclear Operating Company. Subject: Review of south Texas 

30 Project, Units 1 and 2 Individual Plant Examination of External Events (IPEEE) Submittal (JAC 

31 Nos. M83676 and M83677). Washington, D.C. December 15, 1998.

32 [NRC] U.S. Nuclear Regulatory Commission. 2003. SECPOP2000: Sector Population, Land 

33 Fraction, and Economic Estimation Program. Washington, DC: NRC. NUREG/CR-6525, 

34 Rev. 1. August 2003. ADAMS No. ML032310279. 

35 [NRC] U.S. Nuclear Regulatory Commission. 2004. Regulatory Analysis Guidelines of the U.S. 

36 Nuclear Regulatory Commission. Washington, DC: NRC. NUREG/BR-0058, Rev. 4. ADAMS 

37 No. ML003738939.

38 [NRC] U.S. Nuclear Regulatory Commission. 2005. EPRI/NRC-RES Fire PRA Methodology for 

39 Nuclear Power Facilities. Washington, DC: NRC NUREG/CR-6850. September 2005.

40 [NRC] U.S. Nuclear Regulatory Commission. 2007a. Letter from Mohan C. Thadani, U.S. 

41 NRC, to James J. Sheppard, STPNOC. Subject: “South Texas Project Units 1 and 2, Issuance 

42 of Amendments Re: Broad-scope Risk-informed Technical Specifications Amendments (TAC 

43 Nos. MD2341 and MD2342). Washington, D.C. July 13, 2007. ADAMS No. ML071780186.
Appendix F

 

F-36

1 [NRC] U.S. Nuclear Regulatory Commission. 2007b. An Approach for Determining the 

2 Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities. 

3 Regulatory Guide 1.200, Revision 1. Washington, D.C. January 2007. ADAMS 

4 No. ML063170035. 

5 [NRC] U.S. Nuclear Regulatory Commission. 2010. NRC Information Notice 2010-18: Generic 

6 Issue 199, Implications of Updated Probabilistic Seismic Hazard Estimates in Central and 

7 Eastern United States on Existing Plants. Washington, D.C. September 2, 2010. ADAMS 

8 No. ML101970221. 

9 [NRC] U.S. Nuclear Regulatory Commission. 2011a. Letter from Tam Tran, Project Manager, 

10 to G. T. Powell, STPNOC. Subject: Requests for Additional Information for the Review of the 

11 South Texas Project, License Renewal Application. Washington, D.C. May 31, 2011. ADAMS 

12 No. ML11140A015.

13 [NRC] U.S. Nuclear Regulatory Commission. 2011b. Letter from Tam Tran, Project Manager, 

14 to G. T. Powell, STPNOC. Subject: Requests for Additional Information for the Review of the 

15 South Texas Project, License Renewal Application. September 1, 2011. ADAMS 

16 No. ML112360114.

17 [NRC] U.S. Nuclear Regulatory Commission. 2011c. Memorandum from Tam Tran, Project 

18 Manager. Subject: Summary of Telephone Conference Call Held on July 28, 2011 between the 

19 U. S. Nuclear Regulatory Commission and STP Nuclear Operating Company, Concerning 

20 Requests for Additional Information Pertaining to the South Texas Project, License Renewal 

21 Application. August 23, 2011. ADAMS No. ML11216A263.

22 [NRC] U.S. Nuclear Regulatory Commission. 2012. Memorandum from Tam Tran, Project 

23 Manager. Subject: Summary of Telephone Conference Call Held on January 31, 2012 

24 between the U. S. Nuclear Regulatory Commission and STP Nuclear Operating Company, 

25 Concerning Requests for Additional Information Pertaining to the South Texas Project, License 

26 Renewal Application. February 14, 2012. ADAMS No. ML12033A134.

27 [STPNOC] South Texas Project Nuclear Operating Company. 2006. Letter from David W. 

28 Rencurrel, STPNOC to USNRC Document Control Desk, Subject: South Texas Project Units 1 

29 and 2, Docket Nos. STN 50-498, STN 50-499 Revised Broad Scope Risk-Informed Technical 

30 Specification Amendment Request.” Wadsworth, Texas. June 6, 2006. ADAMS 

31 No. ML061630315.

32 [STPNOC] South Texas Project Nuclear Operating Company. 2007. Letter from Charles T. 

33 Bowman, STPNOC, to U.S. Nuclear Regulatory Commission Document Control Desk, Subject: 

34 South Texas Project Units 1 and 2, Docket Nos. STN 50-498, STN 50-499, Response to NRC 

35 Requests for Additional Information on STPNOC Proposed Risk Managed Technical 

36 Specifications (TAC Nos. MD 2341 and MD 2342). Wadsworth, Texas. February 28, 2007. 

37 ADAMS No. ML070670369.

38 [STPNOC] South Texas Project Nuclear Operating Company. 2009. “South Texas Project 

39 Units 3 and 4 Combined License Application (COLA) (Environmental Report), Rev. 3.” 

40 September 2009. ADAMS No. ML092931600.

41 [STPNOC] South Texas Project Nuclear Operating Company. 2010. “South Texas Project—

42 License Renewal Application, Applicant’s Environmental Report, Operating License Renewal 

43 Stage, South Texas Project, Units 1 and 2.” September 2010. ADAMS No. ML103010263.

44 [STPNOC] South Texas Project Nuclear Operating Company. 2011a. Letter from G. T. Powell, 

45 STPNOC, to U.S. Nuclear Regulatory Commission Document Control Desk, Subject: South 

46 Texas Project Units 1 and 2, Docket Nos. STN 50-498, STN 50-499, Response to Request for 
Appendix F

F-37

1 Additional Information on South Texas Project License Renewal Application (TAC No. ME4938). 

2 July 5, 2011. ADAMS No. ML11193A016.

3 [STPNOC] South Texas Project Nuclear Operating Company. 2011b. “Additional Information 

4 on South Texas Project License Renewal Application (TAC No. ME4938).” August 23, 2011. 

5 ADAMS No. ML11250A067.

6 [STPNOC] South Texas Project Nuclear Operating Company. 2012a. Letter from D. W. 

7 Rencurrel, STPNOC, to U.S. Nuclear Regulatory Commission Document Control Desk, Subject: 

8 South Texas Project Units 1 and 2, Docket Nos. STN 50-498, STN 50-499, Supplemental 

9 Response to Request for Additional Information on South Texas Project License Renewal 

10 Application—SAMA (TAC Nos. ME4938 and ME5122). January 19, 2012. ADAMS 

11 No. ML12030A081.

12 [STPNOC] South Texas Project Nuclear Operating Company. 2012b. Letter from D. W. 

13 Rencurrel, STPNOC, to U.S. Nuclear Regulatory Commission Document Control Desk, Subject: 

14 South Texas Project Units 1 and 2, Docket Nos. STN 50-498, STN 50-499, Clarification to 

15 Supplemental Response to Request for Additional Information on South Texas Project License 

16 Renewal Application—SAMA (TAC Nos. ME4938 and ME5122). February 16, 2012. ADAMS 

17 No. ML12053A259.

18 [TVA] Tennessee Valley Authority. 2010. Letter from Masoud Bajestani, TVA, to U.S. Nuclear 

19 Regulatory Commission Document Control Desk. Subject: Watts Bar Nuclear Plant (WBN) 

20 Unit 2—Request for Additional Information Regarding Severe Accident Management 

21 Alternatives (TAC No. MD8203). July 23, 2010. ADAMS No. ML102100588.

22 Texas State Data Center, 2006. Available at: <http://txsdc.utsa.edu/> (Accessed May 2012). 

23 [USGS] U. S. Geological Survey. 2008. 2008 NSHM Gridded Data. Available at: 

24 <http://earthquake.usgs.gov/hazards/products/conterminous/2008/data/#fileformat> (Accessed 

25 May 2012).




UNITED STATES 

NUCLEAR REGULATORY COMMISSION

WASHINGTON, DC 20555-0001

--------------------

OFFICIAL BUSINESS
NUREG-1437

Draft

Supplement 48

Generic Environmental Impact Statement for License Renewal of Nuclear Plants 

Regarding South Texas Project, Units 1 and 2