Risk Assessment Revision for 

40 CFR Part 61 Subpart W – 

Radon Emissions from Operating Mill Tailings 

Task 4 – Detailed Risk Estimates 

Prepared by: 

S. Cohen & Associates 

1608 Spring Hill Road, Suite 400 

Vienna, VA 22182 

under 

Contract Number EP-D-10-042 

Work Assignment No. 1-06, Task 5 

Prepared for: 

U.S. Environmental Protection Agency 

Office of Radiation and Indoor Air 

1200 Pennsylvania Avenue, N.W. 

Washington, DC 20460 

Brian Littleton 

Work Assignment Manager 

November 10, 2011
WA 1-04, Task 5 i SC&A – November 10, 2011

In accordance with the Quality Assurance Project Plan: Risk Assessment Revision for 40 CFR 

Part 61 Subpart W – Radon Emissions from Operating Mill Tailings, this document has been 

reviewed and approved by the following individuals: 

Work Assignment Task Manager: ____________________ 

Stephen F. Marschke 

Date: ___________

Work Assignment Task Manager: ____________________ 

Abe Zeitoun 

Date: ___________

Corporate Quality Assurance Manager/Work 

Assignment Quality Assurance Manager: ____________________ 

Stephen L. Ostrow 

Date: ___________
WA 1-04, Task 5 ii SC&A – November 10, 2011

TABLE OF CONTENTS 

Section Page

Executive Summary ..................................................................................................................... viii

1.0 Introduction and Background ..............................................................................................1

1.1 Dose Calculation Methodology ...............................................................................2

1.2 Methodology to Estimate 2010 Population..............................................................5

2.0 Detailed Risk Estimates .......................................................................................................6

2.1 Sweetwater ...............................................................................................................6

2.1.1 Population and Food Production ................................................................. 7

2.1.2 Meteorology ................................................................................................ 8

2.1.3 Radon Release ............................................................................................. 9

2.1.4 Risk Estimates ........................................................................................... 12

2.2 White Mesa ............................................................................................................12

2.2.1 Population and Food Production ............................................................... 13

2.2.2 Meteorology .............................................................................................. 15

2.2.3 Radon Release ........................................................................................... 16

2.2.4 Risk Estimates ........................................................................................... 18

2.3 Cañon City .............................................................................................................18

2.3.1 Population and Food Production ............................................................... 19

2.3.2 Meteorology .............................................................................................. 21

2.3.3 Radon Release ........................................................................................... 22

2.3.4 Risk Estimates ........................................................................................... 23

2.4 Smith Ranch – Highland ........................................................................................24

2.4.1 Population and Food Production ............................................................... 25

2.4.2 Meteorology .............................................................................................. 26

2.4.3 Radon Release ........................................................................................... 28

2.4.4 Risk Estimates ........................................................................................... 30

2.5 Crow Butte .............................................................................................................31

2.5.1 Population and Food Production ............................................................... 32

2.5.2 Meteorology .............................................................................................. 33

2.5.3 Radon Release ........................................................................................... 35

2.5.4 Risk Estimates ........................................................................................... 37

2.6 Christensen / Irigaray .............................................................................................37

2.6.1 Population and Food Production ............................................................... 39

2.6.2 Meteorology .............................................................................................. 40

2.6.3 Radon Release ........................................................................................... 42

2.6.4 Risk Estimates ........................................................................................... 42

2.7 Alta Mesa 1,2,3 ......................................................................................................43

2.7.1 Population and Food Production ............................................................... 44

2.7.2 Meteorology .............................................................................................. 46

2.7.3 Radon Release ........................................................................................... 47

2.7.4 Risk Estimates ........................................................................................... 48

2.8 Kingsville Dome 1,3 ..............................................................................................49
WA 1-04, Task 5 iii SC&A – November 10, 2011

2.8.1 Population and Food Production ............................................................... 50

2.8.2 Meteorology .............................................................................................. 51

2.8.3 Radon Release ........................................................................................... 51

2.8.4 Risk Estimates ........................................................................................... 52

2.9 Eastern Generic Site – Virginia .............................................................................52

2.9.1 Population and Food Production ............................................................... 53

2.9.2 Meteorology .............................................................................................. 55

2.9.3 Radon Release ........................................................................................... 56

2.9.4 Risk Estimates ........................................................................................... 56

2.10 Western Generic Site – New Mexico .....................................................................57

2.10.1 Population and Food Production ............................................................... 57

2.10.2 Meteorology .............................................................................................. 59

2.10.3 Radon Release ........................................................................................... 60

2.10.4 Risk Estimates ........................................................................................... 60

3.0 Summary of Results ...........................................................................................................61

4.0 References ..........................................................................................................................65

LIST OF FIGURES 

Figure Page

Figure 1: Sweetwater – Aerial View .............................................................................................. 7

Figure 2: White Mesa – Aerial View ........................................................................................... 13

Figure 3: Cañon City – Aerial View ............................................................................................ 19

Figure 4: Cañon City Radon Flux and Annual Release ............................................................... 23

Figure 5: Smith Ranch – Aerial View .......................................................................................... 25

Figure 6: Smith Ranch – Highland – Estimated Time Table of Mining Related Activities ........ 29

Figure 7: Smith Ranch – Highland – Total Estimated Radon Release by Year .......................... 30

Figure 8: Crow Butte – Aerial View ............................................................................................ 31

Figure 9: Crow Butte Total Estimated Semi-Annual Radon Release (1991-2007) ..................... 36

Figure 10: Irigaray – Aerial View ................................................................................................ 38

Figure 11: Christensen – Aerial View ......................................................................................... 39

Figure 12: Alta Mesa – Aerial View ............................................................................................ 44

Figure 13: Kingsville Dome – Aerial View ................................................................................. 49

Figure 14: Potential Uranium in Virginia .................................................................................... 52

Figure 15: Approximate Location of the Eastern Generic Site.................................................... 53

LIST OF TABLES 

Table Page

Table ES-1: Uranium Sites Analyzed .......................................................................................... viii 
WA 1-04, Task 5 iv SC&A – November 10, 2011

Table ES-2: Calculated Total Annual RMEI and Population Dose ............................................... x 

Table ES-3: Calculated Total Annual RMEI and Population Risk................................................ x 

Table 1: Uranium Sites Analyzed .................................................................................................. 1

Table 2: Values for CAP88 Site Independent Parameters ............................................................. 3

Table 3: 2000 to 2010 Population Adjustment Factors ................................................................. 6

Table 4: Sweetwater Population Data ............................................................................................ 7

Table 5: Sweetwater Arithmetic Average Wind Speeds (Wind Towards) .................................... 9

Table 6: Sweetwater Frequencies of Stability Classes (Wind Towards) ....................................... 9

Table 7: Sweetwater Radon Release ............................................................................................ 11

Table 8: Sweetwater Radon Flux Testing Results ....................................................................... 11

Table 9: Sweetwater Risk Assessment Results ............................................................................ 12

Table 10: White Mesa Population Data ....................................................................................... 14

Table 11: White Mesa Arithmetic Average Wind Speeds (Wind Towards) ................................ 15

Table 12: White Mesa Frequencies of Stability Classes (Wind Towards) ................................... 16

Table 13: White Mesa Radon Release .......................................................................................... 17

Table 14: White Mesa Risk Assessment Results ......................................................................... 18

Table 15: Cañon City Population Data ......................................................................................... 20

Table 16: Cañon City Arithmetic Average Wind Speeds (Wind Towards) ................................ 21

Table 17: Cañon City Frequencies of Stability Classes (Wind Towards) .................................... 22

Table 18: Cañon City Annual Radon Release ............................................................................. 22

Table 19: Cañon City Risk Assessment Results .......................................................................... 24

Table 20: Smith Ranch – Highland Population Data .................................................................... 25

Table 21: Smith Ranch – Highland Arithmetic Average Wind Speeds (Wind Towards) ........... 27

Table 22: Smith Ranch – Highland Frequencies of Stability Classes (Wind Towards) .............. 27

Table 23: Smith Ranch – Highland Well Field Annual Radon Release ...................................... 28

Table 24: Smith Ranch – Highland Risk Assessment Results ..................................................... 30

Table 25: Crow Butte Population Data ........................................................................................ 32

Table 26: Crow Butte Arithmetic Average Wind Speeds (Wind Towards) ................................. 34

Table 27: Crow Butte Frequencies of Stability Classes (Wind Towards) .................................... 35

Table 28: Crow Butte Radon Release to the Environment .......................................................... 36

Table 29: Crow Butte Modeled Radon Release ........................................................................... 36

Table 30: Crow Butte Risk Assessment Results .......................................................................... 37

Table 31: Christensen / Irigaray Population Data ........................................................................ 39

Table 32: Christensen / Irigaray Arithmetic Average Wind Speeds (Wind Towards) ................ 41

Table 33: Christensen / Irigaray Frequencies of Stability Classes (Wind Towards) ................... 41

Table 34: Christensen / Irigaray Environmental Radon Release Summary ................................ 42

Table 35: Christensen / Irigaray Estimated Radon Release ......................................................... 42

Table 36: Christensen / Irigaray Risk Assessment Results .......................................................... 42
WA 1-04, Task 5 v SC&A – November 10, 2011

Table 37: Alta Mesa 1,2,3 Population Data ................................................................................. 45

Table 38: Alta Mesa / Kingsville Dome Arithmetic Average Wind Speeds 

(Wind Towards) ........................................................................................................... 46

Table 39: Alta Mesa / Kingsville Dome Frequencies of Stability Classes (Wind Towards) ...... 47

Table 40: Alta Mesa Annual Radon Source Term ....................................................................... 48

Table 41: Alta Mesa Radon Release by Uranium Production ..................................................... 48

Table 42: Alta Mesa Risk Assessment Results ............................................................................ 48

Table 43: Kingsville Dome 1,3 Population Data .......................................................................... 50

Table 44: Kingsville Dome Radon Release by Uranium Production .......................................... 51

Table 45: Kingsville Dome Risk Assessment Results ................................................................. 52

Table 46: Eastern Generic Site (Virginia) Population Data .......................................................... 54

Table 47: Eastern Generic Site (Virginia) Arithmetic Average Wind Speeds 

(Wind Towards) ........................................................................................................... 55

Table 48: Eastern Generic Site (Virginia) Frequencies of Stability Classes (Wind Towards) ..... 56

Table 49: Eastern Generic Site Risk Assessment Results ........................................................... 56

Table 50: Western Generic Site (New Mexico) Population Data ................................................. 58

Table 51: Western Generic Site (New Mexico) Arithmetic Average Wind Speeds 

(Wind Towards) ........................................................................................................... 59

Table 52: Western Generic Site (New Mexico) Frequencies of Stability Classes 

(Wind Towards) ........................................................................................................... 60

Table 53: Western Generic Site Risk Assessment Results .......................................................... 60

Table 54: Cumulative 2000 Population Data ............................................................................... 61

Table 55: Comparison of Current RMEI Location Dose/Risk to WorstCase Location Dose/Risk ............................................................................................. 62

Table 56: Calculated RMEI and Population Dose and Risk Normalized to the 

Radon Release .............................................................................................................. 62

Table 57: Calculated Maximum Total Annual RMEI, Population Dose and Risk ...................... 63

Table 58: Calculated Average Total Annual RMEI, Population Dose and Risk ......................... 64

 
WA 1-04, Task 5 vi SC&A – November 10, 2011

ACRONYMS AND ABBREVIATIONS 

CBR Crow Butte Resources, Inc. 

CFR Code of Federal Regulations 

Ci Curie 

CCD Counter-Current Decantation 

CofA Court of Appeals 

CPP Central Processing Plant 

Dir Direction 

E East 

EA Environmental Assessment 

ENE East Northeast 

ESE East Southeast 

EPA Environmental Protection Agency 

FEIS Final Environmental Impact Statement 

FGR Federal Guidance Report 

HRI Hydro Resources, Inc. 

HUP Highland Uranium Project 

ICRP International Commission on Radiological Protection 

ISL in-situ leach 

km kilometer 

KUC Kennecott Uranium Company 

LCF Latent Cancer Fatalities 

lbs pounds 

m meter 

N North 

NE North East 

NNE North Northeast 

NNW North Northwest 

NW North West 

NESAPS National Emission Standards for Hazardous Air Pollutants 

NMELC New Mexico Environmental Law Center 

NNW North Northwest 

NRC Nuclear Regulatory Commission 

NUREG NUclear REGulatory report 

NW North West 

NWS National Weather Service 

ORIA Office of Radiation and Indoor Air 

ORNL Oak Ridge National Laboratory 

Pb-210 Lead-210 

ppm parts per million 

Ra-226 Radium-226 

RAI Request of Additional Information 

RMEI Reasonably Maximally Exposed Individual 

 
WA 1-04, Task 5 vii SC&A – November 10, 2011

ACRONYMS AND ABBREVIATIONS (Continued) 

Rn-222 Radon-222 

R&D Research and Development 

s second 

S South 

SAG semi-autogenous grinding 

SE South East 

SR Smith Ranch 

SR-HUP Smith Ranch-Highland Uranium Project 

SSE South Southeast 

sq square 

SSW South Southwest 

SW Southwest 

SX Solvent Extraction 

TCEQ Texas Commission on Environmental Quality 

TDH Texas Department of Health 

TDSHS Texas Department of State Health Services 

TEDE Total Effective Dose Equivalent 

TNRCC Texas Natural Resource Conservation Commission 

TRRC Texas Railroad Commission 

U-238 Uranium-238 

U3O8 Triuranium octoxide (yellow cake) 

URI Uranium Resources, Inc. 

V2O5 vanadium pentoxide 

W West 

WNW West Northwest 

WSW West Southwest 

yr year 
WA 1-04, Task 5 viii SC&A – November 10, 2011

EXECUTIVE SUMMARY 

The Office of Radiation and Indoor Air (ORIA) promulgated National Emissions Standards for 

Hazardous Air Pollutants (NESHAPs) for radon emissions from operating uranium mill tailings 

impoundments (Subpart W) on December 15, 1989 (FR 1989). In support of Subpart W, as well 

as other portions of radiolonuclide NESHAPs, ORIA published a three volume Environmental 

Impact Statement (EIS) that provided: 1) a detailed description of the Agency’s procedures and 

methods for estimating radiation dose and risk due to radionuclide emissions to the air (EPA 

1989a), 2) detailed risk estimates for each source of emissions (EPA 1989b, EPA 1989c), and 

3) detailed economic assessments for each source of emissions (EPA 1989d). 

The purpose of this Work Assignment is to revise the risk assessment for the NESHAPs for 

radionuclides from uranium facilities. The information developed in this Work Assignment will 

be used by the Environmental Protection Agency (EPA or the Agency) in the determination of 

whether the existing standards for Subpart W need revising, and, if so, what may represent 

reasonable revisions to the standard. 

The uranium facilities that were analyzed are listed in Table ES-1 and include three existing 

conventional mines/mills, five in-situ leach mines, and two generic sites assumed to be the 

location of conventional mines/mills. 

Table ES-1: Uranium Sites Analyzed

Mill / Mine Type State Regulator Latitude Longitude 

deg min sec deg min sec 

Cañon City Mill Conventional CO State 38 23 46 -105 13 45

Crow Butte In-Situ Leach NE NRC 42 38 41 -103 21 8

Western Generic Conventional NM NRC 35 31 37 -107 52 52

Alta Mesa 1, 2, 3 In-Situ Leach TX State 26 53 59 -98 18 29

Kingsville Dome 1,3 In-Situ Leach TX State 27 24 54 -97 46 51

White Mesa Mill Conventional UT State 37 34 26 -109 28 40

Eastern Generic Conventional VA NRC 38 36 0 -78 1 11

Smith Ranch - Highland In-Situ Leach WY NRC 43 3 12 -105 41 8

Christensen / Irigaray In-Situ Leach WY NRC 43 48 15 -106 2 7

Sweetwater Mill Conventional WY NRC 42 3 7 -107 54 41

In Task 3 of this Work Assignment, an evaluation of existing computer models that could be 

used to perform this dose/risk assessment was performed. As a result of that evaluation, it was 

determined to use the CAP88 computer program, which is based on the AIRDOS and RADRISK 

computer programs (Trinity 2007) that were used in the original 1989 Subpart W evaluation 

(EPA 1989a). Discussion on why CAP88 was selected for this assessment can be found in 

SC&A 2010. 

In order to perform the dose/risk analysis, three types of data were necessary: 1) the distribution 

of the population living within 80 kilometers of each site, 2) the meteorological data at each site, 

particularly the wind speed, wind direction, and stability class, and 3) the amount of radon 

annually released from the site. 
WA 1-04, Task 5 ix SC&A – November 10, 2011

Normally, the population doses and risks are calculated out to a distance of 80 kilometers (50 

miles) from the site. Therefore, it was necessary to know the population to a distance of 80 

kilometers from each site in each of the 16 compass directions. This information is not normally 

available from U.S. Census Bureau data. However, in 1973, the EPA wrote a computer program, 

SECPOP (Sandia 2003), which would convert census block data into the desired 80-kilometer 

population estimates for any specific latitude and longitude within the continental United States. 

The Nuclear Regulatory Commission (NRC) adopted this program to perform citing reviews for 

license applications, and has updated the program to use the 2000 census data. The SECPOP 

program was used to estimate the population distribution around each site; that population was 

then modified to account for changes in the population from 2000 to 2010. 

For those sites where site-specific meteorological data were identified, those site-specific data 

were used. For other sites, CAP88 is provided with a weather library of meteorological data 

from over 350 National Weather Service (NWS) stations. For sites without site-specific 

meteorological data, data from the NWS station nearest the site were used. 

Annual radon release estimates were determined for each site based on the available 

documentation for the site. For example, some sites reported their estimated radon release in 

their semi-annual release reports, while other sites calculated their radon release as part of their 

license application or renewal application. Finally, for some sites, the annual radon release 

estimates were obtained from the NRC-produced site-specific Environmental Assessment. If 

multiple documents provided radon release estimates for a particular site, the estimate from the 

most recent document was used. Likewise, if both theoretical and actual radon release values 

were identified for a site, the actual radon release value was given preference. 

Table ES-2 presents the reasonably maximally exposed individual (RMEI) and population doses 

and risks due to the maximum radon releases estimated for each uranium site. The maximum 

radon releases were used to calculate the doses in order to be able to compare the results to 

regulatory criteria. For example, 10CFR § 20.1301 “Dose limits for individual members of the 

public” restricts the total effective dose equivalent (TEDE) to individual members of the public 

from the licensed operation to less than 100 mrem per year. 10CFR § 20.1301 (e) additionally 

stipulates a licensee must also comply with the, “provisions of EPA's generally applicable 

environmental radiation standards in 40 CFR part 190 shall comply with those standards.” 

However, discharges of radon and its daughters are specifically excepted from compliance with 

the dose criteria of 40 CFR § 190.10(a). 
WA 1-04, Task 5 x SC&A – November 10, 2011

Table ES-2: Calculated Maximum Total Annual RMEI, Population Dose and Risk 

Uranium Site 

Maximum 

Radon 

Release (Ci/yr)

Annual Dose LCF(a) Risk (yr-1

) 

Population 

(person-rem)

RMEI 

(mrem) Population RMEI 

Sweetwater 2,075 0.5 1.2 2.9E-06 6.0E-07 

White Mesa 1,750 5.2 12.0 3.4E-05 6.4E-06 

Cañon City 269 49.2 10.3 3.1E-04 5.4E-06 

Smith Ranch - Highlands 36,500 3.7 1.5 2.3E-05 7.7E-07 

Crow Butte 8,885 2.7 3.3 1.7E-05 1.7E-06 

Christensen / Irigaray 1,600 3.8 1.9 2.4E-05 9.9E-07 

Alta Mesa 740 21.6 11.5 1.3E-04 6.1E-06 

Kingsville Dome 6,958 58.0 11.3 3.8E-04 6.1E-06 

Eastern Generic 1,750 200.3 28.2 1.4E-03 1.6E-05 

Western Generic 1,750 5.1 6.0 2.7E-04 7.7E-06 

(a)Latent Cancer Fatalities

Table ES-3 presents the RMEI and population doses and risks due to the average radon releases 

estimated for each uranium site. The risks were based on average radon releases in order to 

make it easier to convert these annual risk values into lifetime risk values, by simply multiplying 

the Table ES-3 values by the number of years that the facility operates for the population risk or 

by the length of time that the individual lives next to the facility for the RMEI risk. 

Table ES-3: Calculated Average Total Annual RMEI, Population Dose and Risk 

Uranium Site Average Radon 

Release (Ci/yr) 

Annual Dose LCF(a) Risk (yr-1

) 

Population 

(person-mrem)

RMEI 

(rem) Population RMEI 

Sweetwater 1,204 0.3 0.7 1.7E-06 3.5E-07 

White Mesa 1,388 3.0 7.0 2.0E-05 3.7E-06 

Cañon City 146 28.6 6.0 1.8E-04 3.1E-06 

Smith Ranch - Highlands 21,100 2.2 0.9 1.3E-05 4.5E-07 

Crow Butte 4,467 1.6 1.9 1.0E-05 1.0E-06 

Christensen / Irigaray 1,040 2.2 1.1 1.4E-05 5.7E-07 

Alta Mesa 472 12.5 6.7 7.6E-05 3.6E-06 

Kingsville Dome 1,291 33.6 6.6 2.2E-04 3.5E-06 

Eastern Generic 1,388 116.3 16.4 7.9E-04 9.2E-06 

Western Generic 1,388 3.0 3.5 1.6E-04 4.4E-06 

(a)Latent Cancer Fatalities
WA 1-04, Task 5 1 SC&A – November 10, 2011

1.0 INTRODUCTION AND BACKGROUND 

The National Emission Standards for Hazardous Air Pollutants (NESHAPs) includes radon 

emissions for uranium mill tailings (40 CFR Part 61 Subpart W – National Emission Standards 

for Radon Emissions from Operating Mill Tailings – December 15, 1989). At the time of the 

standard’s promulgation, the overwhelming numbers of uranium processing facilities were 

conventional acid or alkaline leach mills. Radon emissions from these facilities were primarily 

from the dried out portions of large (greater than 100-acre) tailings ponds. With the 

promulgation of Subpart W, this large area source was reduced by the requirements to limit the 

size of new tailings areas to either 40 acres for phased disposal or 10 acres for continuous 

disposal (40 CFR 61 Subpart W). Additionally, and more importantly, economic and other 

considerations have led commercial uranium recovery companies to submit license applications/

amendments to develop, upgrade or restart a significant number of in-situ leach (ISL) facilities 

(NRC 2009). 

Table 1: Uranium Sites Analyzed

Mill / Mine Type State Regulator Latitude Longitude 

deg min sec deg min sec 

Cañon City Mill Conventional CO State 38 23 46 -105 13 45 

Crow Butte In-Situ Leach NE NRC 42 38 41 -103 21 8 

Churchrock In-Situ Leach NM NRC 35 31 41 -108 44 33 

Crownpoint In-Situ Leach NM NRC 35 40 41 -108 9 4 

Western Generic Conventional NM NRC 35 31 37 -107 52 52 

Alta Mesa 1, 2, 3 In-Situ Leach TX State 26 53 59 -98 18 29 

Kingsville Dome 1,3 In-Situ Leach TX State 27 24 54 -97 46 51 

Vasquez In-Situ Leach TX State 31 58 6 -99 54 6 

White Mesa Mill Conventional UT State 37 34 26 -109 28 40 

Eastern Generic Conventional VA NRC 38 36 0 -78 1 11 

Smith Ranch - Highland In-Situ Leach WY NRC 43 3 12 -105 41 8 

Christensen / Irigaray In-Situ Leach WY NRC 43 48 15 -106 2 7 

Sweetwater Mill Conventional WY NRC 42 3 7 -107 54 41 

In Section 2.0, detailed risk assessments were performed for all but three of the uranium sites 

listed in Table 1. The reasons for not analyzing three sites (Churchrock, Crownpoint, and 

Vasquez) are described below. 

The Crownpoint and Churchrock uranium deposits, San Juan Basin, New Mexico, are currently 

being developed by Uranium Resources, Inc. (URI) and its subsidiary Hydro Resources, Inc. 

(HRI). Both deposits will be developed using advanced ISL mining techniques. URI/HRI 

currently has about 37.834 million pounds of U3O8 (14,583 tonnes U) of estimated recoverable 

reserves at Crownpoint/Churchrock. In March, 1997, a Final Environmental Impact Statement 

(FEIS) for the Crownpoint/Churchrock sites was completed by the NRC (NRC 1997), which 

recommends the issuance of an operating license. In January 1998, HRI was granted Source 

Material License SUA-1580 by the NRC for uranium production at the Crownpoint/Churchrock 

Uranium Project. Although the license was granted, the project has been delayed due to 

depressed uranium prices and litigation. In December 2002, the NRC found that, since the 

renewal application had been timely filed by HRI, the Crownpoint/Churchrock license would not 
WA 1-04, Task 5 2 SC&A – November 10, 2011

expire until final action had been taken by the NRC on the SUA-1580 renewal application. 

Regarding the litigation, in March 2010, the United States Court of Appeals, Tenth Circuit 

denied the intervener’s petition for review and upheld the NRC’s licensing decision in all 

respects (CofA 2010). In September 2010, the New Mexico Environmental Law Center 

(NMELC) filed an appeal to the U.S. Supreme Court (Docket No. 10-368). On November 15, 

2010, the United States Supreme Court denied NMELC’s petition to review the Appeal Court’s 

ruling, after which URI indicated that construction of the Crownpoint/Churchrock facilities 

should begin in 2012, with production in 2013. Since, to date, there have been no radon releases 

from the Crownpoint/Churchrock Uranium Project, it was determined that a detailed radon risk 

assessment for this licensed site should not be performed. 

The Vasquez uranium site is an ISL mine owned by URI and located in southwestern Duval 

County in South Texas. For the site, URI holds the Texas Natural Resource Conservation 

Commission’s Underground Injection Control Permit: UR03050. The site is also covered by the 

Texas Department of Health’s radioactive materials license: L06353. The Vasquez ISL mine 

was commissioned in October 2004, and reached peak production output in 2005. In 2006 and 

2007, production at Vasquez declined, with 78,600 pounds of uranium in 2007 and 36,600 

pounds in 2008. The last well field at Vasquez was fully depleted of its economically 

recoverable reserves in October 2008, and the project is now undergoing restoration. Vasquez 

did not have a processing plant; rather the uranium loaded resin from Vasquez was delivered to 

the Kingsville Dome central plant for processing. Since the Vasquez ISL mine is no longer 

active, it was determined that a detailed radon risk assessment for this site should not be 

performed. (URI 2010a, URI 2010b) 

1.1 Dose Calculation Methodology 

As part of this Work Assignment, the various computer models that could be used to calculate 

the doses and risks due to the operation of conventional and ISL uranium mines were evaluated. 

Seven computer programs were considered to be used for this risk assessment: CAP88, 

RESRAD-OFFISTE, MILDOS, GENII, MEPAS, AIRDOS, and AERMOD. A detailed 

selection process was used to select the program from the first five programs listed. AIRDOS 

was not included in the detailed selection process, since it is no longer an independent program, 

but has been incorporated into CAP88. Because it only calculates atmospheric dispersion, but 

not radiological doses or risks, AERMOD was also not included in the detailed selection. Each 

of the five programs were given a score of between 0 and 5 for each of the 12 following criteria: 

1) Exposure Pathways Modeled, 2) Population Dose/Risk Capability, 3) Dose Factors Used, 

4) Risk Factors Used, 5) Meteorological Data Processing, 6) Source Term Calculations, 

7) Verification and Validation, 8) Ease of Use/User Friendly, 9) Documentation, 10) Sensitivity 

Analysis Capability, and 12)Probabilistic Analysis Capability. Also, each criterion had a 

weighting factor of between 1 and 2. The total weighted score was calculated for each code, and 

CAP88 was selected for use in this evaluation. SC&A 2010 presents the details of this program 

selection process. CAP88 was developed in 1988 from the AIRDOS, RADRISK, and DARTAB 

computer programs, which had been developed for the EPA at the Oak Ridge National 

Laboratory (ORNL) (Trinity 2007). 
WA 1-04, Task 5 3 SC&A – November 10, 2011

CAP88, which stands for “Clean Air Act Assessment Package-1988,” is used to demonstrate 

compliance with the National Emission Standards for Hazardous Air Pollutants (NESHAPs) 

applicable to radionuclides. CAP88 calculates the doses and risk to the reasonably maximally 

exposed individual (RMEI) and as well as the surrounding population. Exposure pathways 

evaluated by CAP88 are: inhalation, air immersion, ingestion of vegetables, meat, and milk, and 

ground surface exposure. CAP88 uses a modified Gaussian plume equation to estimate the 

average dispersion of radionuclides released from up to six emitting sources. The sources may 

be either elevated stacks, such as a smokestack, or uniform area sources, such as a pile of 

uranium mill tailings. Plume rise can be calculated assuming either a momentum or buoyantdriven plume. Assessments are done for a circular grid of distances and directions for a radius of 

up to 80 kilometers (50 miles) around the facility. The Gaussian plume model produces results 

that agree with experimental data as well as any model, is fairly easy to work with, and is 

consistent with the random nature of turbulence. CAP88 incorporates dose and risk factors from 

Federal Guidance Report 13 (FGR 13, EPA 1999) in place of the RADRISK data that were used 

in previous versions. The FGR 13 factors are based on the methods in Publication 72 of the 

International Commission on Radiological Protection (ICRP 1972). A description of the 

mathematical models used by CAP88 is provided in the CAP88 Users Manual (Trinity 2007). 

CAP88 requires the distribution of the population surrounding the site and the characteristics of 

the local meteorology. The methodology used to estimate the population distributions is 

described in the following section, Section 1.2, while the estimated distributions are presented in 

the Section 2.0 site-specific subsections. For those sites where site-specific meteorological data 

were identified, site-specific data were used. For other sites, CAP88 is provided with a weather 

library of meteorological data from over 350 National Weather Service (NWS) stations. For sites 

without site-specific meteorological data, the data from the NWS station nearest the site were 

used, as described in the Section 2.0 site-specific subsections. 

Additionally, CAP88 requires much data that is radionuclide-independent and usually 

independent of the site being analyzed. Table 2 is a listing of the radionuclide- and siteindependent parameters, along with the default values that are provided with CAP88 and that 

were used for these uranium site dose and risk analyses. 

Table 2: Values for CAP88 Site Independent Parameters

Parameter (Units) Value 

Human Inhalation Rate 

 Cubic centimeters/hr 9.17E+05 

Soil Parameters 

 Effective surface density (kg/sq m, dry weight) 

(Assumes 15 cm plow layer) 

2.15E+02 

Buildup Times 

 For activity in soil (years) 1.00E+02 

 For radionuclides deposited on ground/water (days) 3.65E+02 
WA 1-04, Task 5 4 SC&A – November 10, 2011

Table 2: Values for CAP88 Site Independent Parameters

Parameter (Units) Value 

Delay Times 

 Ingestion of pasture grass by animals (hr) 0.00E+00 

 Ingestion of stored feed by animals (hr) 2.16E+03 

 Ingestion of leafy vegetables by man (hr) 3.36E+02 

 Ingestion of produce by man (hr) 3.36E+02 

 Transport time from animal feed-milk-man (day) 2.00E+00 

 Time from slaughter to consumption (day) 2.00E+01 

Weathering 

 Removal rate constant for physical loss (per hr) 2.90E-03 

Crop Exposure Duration 

 Pasture grass (hr) 7.20E+02 

 Crops/leafy vegetables (hr) 1.44E+03 

Agricultural Productivity 

 Grass-cow-milk-man pathway (kg/sq m) 2.80E-01 

 Produce/leafy vegetables for human consumption (kg/sq m) 7.16E-01 

Fallout Interception Fractions 

 Vegetables 2.00E-01 

 Pasture 5.70E-01 

Grazing Parameters 

 Fraction of year animals graze on pasture 4.00E-01 

 Fraction of daily feed that is pasture grass when animal grazes on pasture 4.30E-01 

Animal Feed Consumption Factors 

 Contaminated feed/forage (kg/day, dry weight) 1.56E+01 

Dairy Productivity 

 Milk production of cow (L/day) 1.10E+01 

Meat Animal Slaughter Parameters 

 Muscle mass of animal at slaughter (kg) 2.00E+02 

 Fraction of herd slaughtered (per day) 3.81E-03 

Decontamination 

 Fraction of radioactivity retained after washing for leafy vegetables and produce 5.00E-01 

Fractions Grown In Garden Of Interest 

 Produce ingested 1.00E+00 

 Leafy vegetables ingested 1.00E+00 

Ingestion Ratios: 

Immediate Surrounding Area/Total Within Area 

 Vegetables 7.00E-01 

 Meat 4.40E-01 

 Milk 4.00E-01 

Minimum Ingestion Fractions From Outside Area 

(Actual fractions of food types from outside area can be greater than the minimum 

fractions listed below.) 

 Vegetables 0.00E+00 

 Meat 0.00E+00 

 Milk 0.00E+00 
WA 1-04, Task 5 5 SC&A – November 10, 2011

Table 2: Values for CAP88 Site Independent Parameters

Parameter (Units) Value 

Human Food Utilization Factors 

 Produce ingestion (kg/y) 1.76E+02 

 Milk ingestion (L/y) 1.12E+02 

 Meat ingestion (kg/y) 8.50E+01 

 Leafy vegetable ingestion (kg/y) 1.80E+01 

1.2 Methodology to Estimate 2010 Population 

In order to calculate the dose and risk to the population surrounding the uranium site, it is 

necessary to know the distribution of the surrounding population at each site. Normally, the 

population doses and risks are calculated out to a distance of 80-kilometers (50-miles) from the 

site. Therefore, it is necessary to know the population to a distance of 80-kilometers from each 

site in each of the 16 compass directions. This information is not normally available from census 

data to the degree of specificity needed in this assessment. However, in 1973, the EPA wrote a 

computer program, SECPOP, that would convert census block data into the desired 80-kilometer 

population estimates for any specific latitude and longitude within the continental United States 

(Sandia 2003). The NRC adopted this program to perform siting reviews for license 

applications, and has updated the program to use the 2000 census data. 

The latitude and longitude for each uranium site listed in Table 1 was entered into SECPOP, 

which calculated the 80-kilometer, 16-sector 2000 population distribution for each site. The 

SECPOP-calculated population distributions are provided in the site-specific subsections of 

Section 2.0. 

It was desired to use 2010 population data rather than the 2000 census data available in 

SECPOP. The U.S. Census Bureau has estimates of the population in every county for each year 

from 2001 though 2009 (http://www.census.gov/popest/counties/files/CO-EST2009-

ALLDATA.csv). For each uranium site, the 2000 census data and 2009 estimate were used to 

calculate an annual population adjustment factor specific for the county in which the site is 

located. That annual adjustment factor was then used to calculate an adjustment factor to bring 

the SECPOP population distribution from 2000 to 2010. 
WA 1-04, Task 5 6 SC&A – November 10, 2011

Table 3: 2000 to 2010 Population Adjustment Factors

Site State County Population Factor 

2000 2009 Annual 2010 

Cañon City Mill CO Fremont 46145 47815 0.0040 1.04 

Crow Butte NE Dawes 9060 8735 -0.0041 0.96 

Western Generic NM McKinley 74798 70513 -0.0065 0.94 

Alta Mesa 1, 2, 3 TX Brooks 7976 7377 -0.0086 0.92 

Kingsville Dome 1,3 TX Kleberg 31549 30647 -0.0032 0.97 

White Mesa Mill UT San Juan 14413 15049 0.0048 1.05 

Eastern Generic VA Culpeper 34262 46502 0.0345 1.40 

Smith Ranch – Highland WY Converse 12052 13578 0.0133 1.14 

Christensen / Irigaray WY Campbell 33698 43967 0.0300 1.34 

Sweetwater Mill WY Sweetwater 37613 41226 0.0102 1.11 

2.0 DETAILED RISK ESTIMATES 

For each uranium site that is analyzed, this section presents a brief description, including an 

aerial view of the site, followed by the population distribution surrounding the site and the 

assumptions made concerning food production. The meteorological data used to analyze each 

site are presented next. Lastly, the methodology used to estimate the annual radon released from 

each site is discussed and the radon release presented. 

2.1 Sweetwater1

The Sweetwater Uranium Project, the only conventional mill remaining in Wyoming, consists of 

a mill and ancillary structures and is located some 65 km northwest of the Town of Rawlins, in 

south-central Wyoming’s Great Divide Basin. The mill was constructed in 1979 and 1980 and 

NRC source materials license SUA-1350 (Docket Number: 40-8584) was obtained in February 

1979 to permit processing of uranium ore. The mill operated between 1981 and 1983 and has 

been on standby status since mid-1983. During its three years of operation, the Sweetwater 

facility produced a total of 1,292,000 lbs of U3O8 from a total of 2,340,535 tons of ore (sourced 

from an adjacent, now depleted ore body which has since been reclaimed), at a reported recovery 

rate of 90%. Operations at Sweetwater are currently suspended; however, the license has been 

renewed, and is currently set to expire on November 10, 2014. The Kennecott Uranium 

Company (KUC) operates and manages the Sweetwater Uranium Project for the Green Mountain 

Mining Venture. With the continued increase in the price of uranium, KUC may either sell or 

restart the Sweetwater mill, shown in Figure 1. 

 

1

 The description of the Sweetwater site was abstracted from various sources, including KUC 1994, KUC 2004, 

and Uranium One 2006, while the aerial view of the Sweetwater site was obtained from Google Maps. 
WA 1-04, Task 5 7 SC&A – November 10, 2011

Figure 1: Sweetwater – Aerial View 

2.1.1 Population and Food Production 

The 80-kilometer population distribution in each of the 16 principal compass directions, which 

was calculated for the Sweetwater site by SECPOP and used in CAP88 for population dose 

calculations, is shown in Table 4. To adjust the 2000 population data to 2010, the CAP88 

Sweetwater population dose was multiplied by 1.11, see Section 1.2 and Table 3. 

Table 4: Sweetwater Population Data 

Dir Distance (km) 

0 to 1 1 to 2 2 to 3 3 to 4 4 to 5 5 to 10 10 to 20

N 0 0 0 0 0 0 0 

NNW 0 0 0 0 0 0 0 

NW 0 0 0 0 0 3 0 

WNW 0 0 0 0 0 0 0 

W 0 0 0 0 0 0 0 

WSW 0 0 0 0 0 0 0 

SW 0 0 0 0 0 0 0 

SSW 0 0 0 0 0 0 0 

S 0 0 0 0 0 0 0 

SSE 0 0 0 0 0 0 0 

SE 0 0 0 0 0 0 0 

ESE 0 0 0 0 0 0 0 

E 0 0 0 0 0 0 0 

ENE 0 0 0 0 0 0 0 

NE 0 0 0 0 0 0 0 

NNE 0 0 0 0 0 0 3 
WA 1-04, Task 5 8 SC&A – November 10, 2011

Table 4: Sweetwater Population Data 

Dir Distance (km) 

20 to 30 30 to 40 40 to 50 50 to 60 60 to 70 70 to 80 

N 0 3 75 26 0 0 

NNW 0 0 2 37 0 7 

NW 0 0 0 0 0 19 

WNW 0 0 0 0 0 0 

W 0 2 0 2 0 0 

WSW 0 0 0 0 0 0 

SW 0 0 0 2 102 1 

SSW 2 47 0 3 0 0 

S 0 0 256 0 2 0 

SSE 0 2 2 0 12 0 

SE 0 3 43 0 0 0 

ESE 0 5 7 137 9097 430 

E 3 11 18 5 0 3 

ENE 3 0 19 16 0 5 

NE 10 97 3 6 7 13 

NNE 3 0 0 29 21 0 

The agricultural productivity factors for Wyoming were taken from Appendix C of the CAP88 

User’s Manual, as shown below, and used in the Sweetwater site population dose calculation. 

Beef Cattle Density (cattle/km2): 5.12 

Milk Cattle Density (cow/km2): 0.0579 

Land Cultivated for Vegetable Crops: 0.159% 

The distance and direction to the RMEI were identified in the Revised Environmental Report 

(KUC 1994) as: 

The nearest resident is approximately 17 air miles northeast of the Site and the nearest 

town is Bairoil, located approximately 22 air miles northeast of the Site. [KUC 1994, 

page 1-1] 

Notice, that the Table 4 SECPOP estimate places the nearest individual at a distance of 5 km to 

10 km in the NW direction. To calculate the RMEI dose and risk for this study, the Table 4 

RMEI distance and direction were used. 

2.1.2 Meteorology 

The CAP88 computer program is provided with a weather library of meteorological data from 

over 350 NWS stations. For the Sweetwater site, the CAP88-provided meteorological data for 

the period 1983 through 1987 was obtained from the site’s Revised Environmental Report (KUC 

1994) and the associated MILDOS analysis (EnecoTech 1994). Table 5 shows the directionaldependent average wind speed for each stability class, while Table 6 gives the stability class 

frequency. 
WA 1-04, Task 5 9 SC&A – November 10, 2011

Table 5: Sweetwater Arithmetic Average Wind Speeds (Wind Towards) 

Dir Pasquill Stability Class (m/s) 

A B C D E F G 

N 0.000 1.812 2.477 7.722 5.786 2.497 0.000 

NNW 0.000 1.423 2.153 7.706 5.898 2.328 0.000 

NW 0.000 1.696 1.780 6.684 6.140 2.475 0.000 

WNW 0.000 1.501 1.740 6.256 5.517 2.432 0.000 

W 0.000 1.365 1.667 6.705 5.685 2.294 0.000 

WSW 0.000 1.918 1.897 7.114 5.984 2.410 0.000 

SW 0.000 2.045 2.380 6.838 5.788 2.797 0.000 

SSW 0.000 1.825 1.982 7.633 5.820 2.955 0.000 

S 0.000 1.042 1.177 7.021 6.227 2.171 0.000 

SSE 0.000 1.042 1.026 8.634 7.032 1.384 0.000 

SE 0.000 1.822 2.446 8.762 5.876 2.981 0.000 

ESE 0.000 1.984 2.553 9.262 6.150 3.028 0.000 

E 0.000 1.708 2.681 8.078 5.647 2.606 0.000 

ENE 0.000 1.851 2.583 8.400 6.069 2.666 0.000 

NE 0.000 1.507 2.422 8.611 6.027 2.714 0.000 

NNE 0.000 1.549 2.438 8.144 5.963 2.709 0.000 

Table 6: Sweetwater Frequencies of Stability Classes (Wind Towards) 

Dir Pasquill Stability Class (frequency) 

A B C D E F G

N 0.0000 0.0203 0.1677 0.5699 0.0624 0.1797 0.0000 

NNW 0.0000 0.0266 0.1551 0.5723 0.0650 0.1811 0.0000 

NW 0.0000 0.0197 0.2033 0.4704 0.0827 0.2240 0.0000

WNW 0.0000 0.0275 0.1880 0.3991 0.0753 0.3100 0.0000 

W 0.0000 0.0248 0.1914 0.4613 0.0794 0.2430 0.0000 

WSW 0.0000 0.0217 0.1591 0.5108 0.0690 0.2394 0.0000 

SW 0.0000 0.0177 0.1398 0.4836 0.0945 0.2644 0.0000

SSW 0.0000 0.0234 0.1128 0.4580 0.1166 0.2893 0.0000 

S 0.0000 0.0096 0.1540 0.3018 0.0882 0.4464 0.0000 

SSE 0.0000 0.0222 0.0630 0.7737 0.0670 0.0741 0.0000 

SE 0.0000 0.0080 0.0269 0.7848 0.0716 0.1087 0.0000

ESE 0.0000 0.0021 0.0542 0.7959 0.0542 0.0935 0.0000 

E 0.0000 0.0103 0.0913 0.7018 0.0569 0.1397 0.0000 

ENE 0.0000 0.0114 0.0960 0.6874 0.0683 0.1370 0.0000 

NE 0.0000 0.0102 0.0859 0.7059 0.0680 0.1301 0.0000

NNE 0.0000 0.0089 0.1197 0.6475 0.0712 0.1527 0.0000 

TOTAL 0.0000 0.0156 0.1269 0.6039 0.0713 0.1821 0.0000 

2.1.3 Radon Release 

Even though KUC provides the NRC with semi-annual effluent reports for the Sweetwater site, 

as required by 10CFR §40.65, radon releases are not included. Rather, KUC provides the 

upwind and downwind radon concentrations. Thus, in order to perform the risk assessment, it 
WA 1-04, Task 5 10 SC&A – November 10, 2011

was necessary to refer to the Revised Environmental Report (KUC 1994) for a Sweetwater sitespecific radon source term. The following information on radon releases was taken from Section 

3.4 of the Sweetwater Revised Environmental Report (KUC 1994). 

Ore Stockpiles, Crushing and Grinding 

A total of 604.6 Ci/year of radon is estimated to be released by ore handling, including 

both radon release from the mill exhaust stack and the ore loading area at the grizzly. 

[KUC 1994, page 3-9] 

Leaching 

The leach tanks are covered and are also equipped with a vent system. The air in the 

tanks will have small concentrations of radon-222 and sulfuric acid mist. This air will be 

vented through a wet scrubber (...). Exhaust from the scrubber will contain traces of 

radon-222. [KUC 1994, page 3-9] 

Counter-Current Decantation (CCD) Thickening

Some water vapor, acid mist, and minor amounts of radon-222 will escape into the 

atmosphere from the open thickeners. [KUC 1994, page 3-11] 

In accordance with 40 CFR 61, the tailings impoundments will be 40 acres in area at 

capacity and no more than two impoundments will be operated at any one time. Radon222 emissions will be minimized from the tailings impoundment, by keeping the tailings 

in the operating cell wet. When operations are complete, the final surface area of the six 

reclaimed impoundments and the original impoundment, to be used as an evaporation 

pond, is estimated to be approximately 280 acres. Assuming the maximum allowable 

emission of 20.0 pCi/m2

/sec after reclamation, annual radon-222 emissions can be no 

more than 714 Ci/year for the six proposed impoundments and the existing 

impoundment, combined. [KUC 1994, page 3-11] 

Solvent Extraction 

Section 3.4 of the Revised Environmental Report does not provide any radon source term for the 

solvent extraction phase. 

Precipitation 

Air from the yellowcake precipitators, and thickener area will be passed through a wet 

scrubber and vented to the atmosphere from stack S-6 (...). The exhaust gases will 

contain approximately 80 - 120 ppm ammonia and traces of radon-222. [KUC 1994, page 

3-12] 

In addition to the source term discussion provided in Section 3.4, the Revised Environmental 

Report provides estimated annual radon releases for the facility during operation at specific 

release points in Table 5.2-1, which has been reproduced in this report as Table 7. Unlike 

Section 3.4, which is specific to the mill area, Table 5.2-1 includes the radon releases from “the 
WA 1-04, Task 5 11 SC&A – November 10, 2011

six proposed [in 1994] 40-acre tailings cells, and the existing [in 1994] tailings cell.” From 

Table 7, it can be seen that including the radon contribution from the tailing cells results in a 

time-dependent annual radon release. 

Table 7: Sweetwater Radon Release 

Source 

Radon 

Release 

(Ci/yr) 

Dryer ―

Ore Receiving 604.6 

Leaching ―

Ore Handling and Storage ―

Ore Dust ―

Tailings 

Yr. 1-3 1001 

Yr. 4-6 2861 

Yr. 7-9 2963 

Yr. 10-12 3065 

Yr. 13-15 3167 

Yr. 16-18 3269 

Yr. 19-21 2370 

Yr. 22-24 714 

Source: KUC 1994, Table 5.2-1 

It should also be noted that the tailing cell radon releases shown in Table 7 were based on an 

assumed radon flux of 20 pCi/m2-s from each of the covered cells or impoundments. To 

demonstrate compliance with 40CFR Part 61, Subpart W, KUC has annually conducted testing 

on the facility’s tailings impoundment for radon emissions (KUC 2004). The results of that 

testing are shown in Table 8. In addition to showing the measured radon flux, Table 8 also 

shows what the largest annual radon tailing release would be, based on the measured flux, as 

opposed to using the 40CFR §61.252 standard of 20 pCi/m2-s. 

Table 8: Sweetwater Radon Flux 

Testing Results 

Test Date Radon Flux 

(pCi/m2-s) 

Yr. 16-18 Tailings 

Release (Ci/yr) 

7-Aug-90 9.00 1471 

13-Aug-91 5.10 834 

5-Aug-92 5.60 915 

24-Aug-93 5.00 817 

23-Aug-94 5.00 817 

15-Aug-95 3.59 587 

13-Aug-96 5.47 894 

26-Aug-97 4.23 691 

11-Aug-98 2.66 435 

10-Aug-99 1.27 208 
WA 1-04, Task 5 12 SC&A – November 10, 2011

Table 8: Sweetwater Radon Flux 

Testing Results 

Test Date Radon Flux 

(pCi/m2-s) 

Yr. 16-18 Tailings 

Release (Ci/yr) 

8-Aug-00 4.05 662 

15-Aug-01 6.98 1141 

14-Aug-02 4.10 670 

13-Aug-03 7.11 1162 

Source: KUC 2004, Appendix 6, Page 1 

Based on the radon release data provided in Table 7 and Table 8, several annual radon releases 

may be calculated: 

§61.252 Standard, Maximum 3,874 Ci/yr 

§61.252 Standard, Average 3,031 Ci/yr 

Measured, Maximum 2,075 Ci/yr 

Measured, Average 1,204 Ci/yr 

2.1.4 Risk Estimates 

The RMEI and population doses and risks calculated by CAP88 for the Sweetwater site are 

shown in Table 9. 

Table 9: Sweetwater Risk Assessment Results 

Receptor / Impact 

Radon Release (Ci/yr) 

Unitized Maximum Average 

1 2075 1204 

RMEI 

(7500m NW) 

Dose (mrem/yr) 5.6E-04 1.2E+00 6.7E-01 

LCF Risk (yr-1) 2.9E-10 6.0E-07 3.5E-07 

Population Dose (person-rem/yr) 2.3E-04 4.9E-01 2.8E-01 

LCF Risk (yr-1) 1.4E-09 2.9E-06 1.7E-06 

2.2 White Mesa2

The White Mesa mill is a fully licensed, conventional uranium processing mill with a vanadium 

co-product recovery circuit, shown in Figure 2. Located six miles south of Blanding, Utah, in 

the southeastern part of the state, White Mesa is the only conventional uranium mill currently 

operating in the United States. The White Mesa mill is licensed by the state of Utah 

(Radioactive Materials License: UT1900479), and is owned and operated by Denison Mines 

(USA). Construction of the White Mesa mill started in 1979, and conventionally mined 

 

2

 The description of the White Mesa site was abstracted from various sources, including Denison 2007 and 

Melbye 2008, while the aerial view of the White Mesa site was obtained from Google Maps. 
WA 1-04, Task 5 13 SC&A – November 10, 2011

uranium/vanadium ore was first processed in May 1980. To date, White Mesa has produced 

over 30 million pounds of U3O8 and 33 million pounds of V2O5. 

Figure 2: White Mesa – Aerial View 

Operations at White Mesa begin with weighting, receiving, sampling, and stockpiling of 

conventional ore and other feed materials from various offsite sources. Mine ore, as well as 

stockpiled crushed ore, is fed into the semi-autogenous grinding (SAG) mill. The ground feed 

material, stored as a wet slurry in one of two agitated tanks, is then fed to the first stage of leach. 

The two-stage acid leach is followed by the recovery of uranium bearing pregnant solution in a 

CCD system. Once the pregnant solution is clarified, it is pumped to the solvent extraction (SX) 

circuit. Vanadium, when recovered, is stripped from the barren uranium raffinate, also using a 

solvent extraction circuit. Both uranium and vanadium are precipitated in their respective 

circuits, followed by drying and packaging. 

2.2.1 Population and Food Production 

The 80-kilometer population distribution in each of the 16 principal compass directions, which 

was calculated for the White Mesa site by SECPOP and used in CAP88 for population dose 

calculations, is shown in Table 10. To adjust the 2000 population data to 2010, the CAP88 

White Mesa population dose was multiplied by 1.05, see Section 1.2 and Table 3. 
WA 1-04, Task 5 14 SC&A – November 10, 2011

Table 10: White Mesa Population Data 

Dir Distance (km) 

0 to 1 1 to 2 2 to 3 3 to 4 4 to 5 5 to 10 10 to 20

N 0 0 3 69 567 2813 73 

NNW 0 0 0 0 0 24 0 

NW 0 0 52 0 0 0 0 

WNW 0 0 0 0 0 0 0 

W 0 0 0 0 0 0 0 

WSW 0 0 0 0 0 1 0 

SW 0 0 0 0 0 0 0 

SSW 0 0 0 0 0 0 0 

S 0 0 0 0 0 7 247 

SSE 0 5 0 0 0 0 40 

SE 0 0 0 0 0 0 12 

ESE 0 0 0 0 0 0 0 

E 0 0 0 0 0 0 0 

ENE 0 14 0 0 0 0 0 

NE 0 0 0 0 180 0 1 

NNE 0 0 0 79 0 25 16 

Dir Distance (km) 

20 to 30 30 to 40 40 to 50 50 to 60 60 to 70 70 to 80 

N 0 0 6 4 0 28 

NNW 0 0 0 0 16 0 

NW 0 0 0 0 0 0 

WNW 0 0 0 0 0 0 

W 0 8 8 2 0 2 

WSW 0 0 0 0 0 0 

SW 0 2 0 88 352 195 

SSW 0 195 163 19 175 367 

S 1 307 105 264 488 617 

SSE 62 710 431 116 159 539 

SE 83 232 860 340 14 5 

ESE 3 8 22 140 231 3045 

E 0 2 135 130 463 1361 

ENE 7 26 88 1046 168 6 

NE 10 100 91 165 66 6 

NNE 61 2035 51 9 8 1 

The agricultural productivity factors for Utah were taken from Appendix C of the CAP88 User’s 

Manual, as shown below, and used in the White Mesa site population dose calculation. 

Beef Cattle Density (cattle/km2): 2.84 

Milk Cattle Density (cow/km2): 0.446 

Land Cultivated for Vegetable Crops: 0.183% 

The distance and direction to the RMEI were identified in the Cell 4B dose assessment (SENES 

2008) as: 
WA 1-04, Task 5 15 SC&A – November 10, 2011

... the nearest “potential” resident is approximately 1.2 miles (1.9 km) north of the Mill, 

near the location of air monitoring station BHV-I. The nearest actual resident is located 

approximately 1.6 miles (2.5 km) north of the mill. [SENES 2008, page 5-3] 

Notice that the Table 10 SECPOP estimate places the nearest individuals to White Mesa at a 

distance of 1 to 2 km in the SSE and ENE directions. To calculate the RMEI dose and risk for 

this study, the Table 10 RMEI distances and directions were used, since they are closer than the 

nearest actual resident. 

2.2.2 Meteorology 

The White Mesa mill has an onsite meteorological monitoring station that records wind speed, 

wind direction, and stability class. This onsite meteorological data were used by Denison to 

formulate a joint frequency distribution for the dose calculations performed as part of their White 

Mesa license renewal application. For this risk assessment, the meteorological data from the 

license renewal application was reformatted so that it could be processed by the CAP88 auxiliary 

program, WINDGET (Trinity 2007), which generated a meteorological data file in the format 

required by CAP88 (i.e., a .WND file). Table 11 shows the directional-dependent average wind 

speed for each stability class that was used in this risk assessment, while Table 12 gives the 

stability class frequency. 

Table 11: White Mesa Arithmetic Average Wind Speeds (Wind Towards) 

Dir Pasquill Stability Class (m/s) 

A B C D E F G 

N 2.727 4.293 5.984 7.051 3.651 1.924 0.000 

NNW 2.670 4.234 5.430 5.673 3.186 1.857 0.000 

NW 2.495 4.375 5.509 6.080 2.818 1.793 0.000 

WNW 2.341 3.914 4.958 5.741 3.011 1.650 0.000 

W 2.065 3.635 5.898 5.238 2.980 1.684 0.000 

WSW 2.086 3.598 5.089 5.043 2.779 1.745 0.000 

SW 1.833 3.217 4.058 4.495 3.280 1.956 0.000 

SSW 2.130 3.399 3.697 4.366 4.326 2.229 0.000 

S 1.993 3.388 4.827 5.115 4.516 2.343 0.000 

SSE 2.245 4.794 6.375 7.140 4.766 2.429 0.000 

SE 2.384 4.103 6.302 7.199 4.302 2.289 0.000 

ESE 2.378 4.104 5.912 5.791 3.457 2.178 0.000 

E 2.381 4.290 6.150 7.401 3.951 2.222 0.000 

ENE 2.571 4.617 6.414 7.725 4.031 1.915 0.000 

NE 2.773 4.565 6.196 7.945 4.018 1.957 0.000 

NNE 2.910 4.580 6.102 8.225 4.523 2.077 0.000 
WA 1-04, Task 5 16 SC&A – November 10, 2011

Table 12: White Mesa Frequencies of Stability Classes (Wind Towards) 

Dir Pasquill Stability Class (m/s) 

A B C D E F G

N 0.2581 0.2125 0.1837 0.2509 0.0372 0.0576 0.0000 

NNW 0.3351 0.2376 0.1578 0.1507 0.0319 0.0869 0.0000 

NW 0.3286 0.1690 0.1314 0.2253 0.0282 0.1174 0.0000

WNW 0.3637 0.1318 0.0727 0.1545 0.0500 0.2273 0.0000 

W 0.3938 0.0933 0.0622 0.1088 0.0778 0.2642 0.0000 

WSW 0.3098 0.1059 0.0784 0.1726 0.0588 0.2745 0.0000 

SW 0.1223 0.0526 0.0782 0.3912 0.1579 0.1977 0.0000

SSW 0.0334 0.0193 0.0405 0.4585 0.3331 0.1151 0.0000 

S 0.0473 0.0164 0.0327 0.4064 0.3273 0.1700 0.0000 

SSE 0.0595 0.0280 0.0653 0.5449 0.1272 0.1750 0.0000 

SE 0.0794 0.0451 0.1155 0.4567 0.1119 0.1913 0.0000

ESE 0.1575 0.0822 0.1575 0.3390 0.0788 0.1849 0.0000 

E 0.1749 0.0933 0.1399 0.3907 0.0787 0.1224 0.0000 

ENE 0.1885 0.1195 0.1747 0.3839 0.0529 0.0805 0.0000 

NE 0.1781 0.1557 0.2380 0.3383 0.0359 0.0539 0.0000

NNE 0.1888 0.1958 0.2118 0.3247 0.0380 0.0410 0.0000 

TOTAL 0.1560 0.0999 0.1161 0.3595 0.1397 0.1287 0.0000 

2.2.3 Radon Release 

SENES 2008 presents the results of a dose assessment that was performed to quantify the dose 

impact from the proposed development of new tailings Cell 4B. Two sources of uranium ore are 

considered for processing by the White Mesa mill: Colorado Plateau (0.25% U3O8 and 1.5% 

V2O5) and Arizona Strip (0.637% U3O8 and no V2O5). For both ores, Section 4 of SENES 2008 

documents the source term, including radon, from each area of the White Mesa mill, and is 

summarized below. 

Grinder 

The Rn-222 concentration in the ore was assumed to be equal to the U-238 concentration. 

The Rn-222 released during wet grinding is 92.7 and 236 Ci/yr for Colorado Plateau and 

Arizona Strip ore, respectively. [SENES 2008, page 4-3] 

Ore Dump to Grizzly 

SENES 2008 does not indicate any radon release from the grizzly (i.e., screener). 

Yellowcake Stacks 

Since the ore processing steps reject nearly all the radium to the tailings, very little radon 

is released during the production of yellowcake. No significant radon releases occur 

during yellowcake drying and packaging, since only about 0.1% of the original Ra-226 in 

the ore is found in yellowcake. Therefore, the amount of Rn-222 emitted from the 

yellowcake stack was assumed to be negligible. [SENES 2008, page 4-4] 
WA 1-04, Task 5 17 SC&A – November 10, 2011

Vanadium Stack 

..., the emissions from the remaining radionuclides [including radon] were assumed to be 

negligible and in any event would likely be discharged to the tailings cells. [SENES 

2008, page 4-4] 

Ore Pads 

Rn-222 will be produced in the ore pads from the decay of Ra-226. The estimated annual 

radon release rate from the ore pads is 375 and 956 Ci/yr for Colorado Plateau and 

Arizona Strip ore, respectively. [SENES 2008, page 4-5] 

Active Tailings Cells 

..., the total annual radon release rates for active tailings cell 3 and 4A and 4B were 

estimated to be 179 Ci/yr for tailings cell 3 and 102 Ci/yr for each of tailings cells 4A and 

4B. These estimates are extremely conservative because it was assumed that the radon 

release rate of 20 pCi/m2

s (...) occurred over the entire area of each cell. [SENES 2008, 

page 4-7] 

Inactive Tailings Cells 

..., the total annual radon release from the tailings cells 2 and 3 with interim soil covers 

were 85.3 and 89.4 Ci/yr, respectively. [SENES 2008, page 4-7] 

Table 13 summarizes the SENES 2008 annual radon release from the White Mesa uranium mill. 

Table 13: White Mesa Radon Release 

Source 

Radon Release (Ci/yr) 

Colorado 

Plateau 

Arizona 

Strip 

Grinding 92.7 236 

Ore Dump to Grizzly ―

Ore Pads 375 956 

North Yellowcake Stack ―

South Yellowcake Stack ―

Tailing Cell 2: Interim Soil Cover 85.3 

Tailing Cell 3: Interim Soil Cover 89.4 

Tailing Cell 3: Active 179 

Tailing Cell 4A: Active 102 

Tailing Cell 4B: Active 102 

Vanadium Stack ― N/A 

Total 1,025 1,750 

Source: SENES 2008, Tables 4.5-1 and 4.5-2 
WA 1-04, Task 5 18 SC&A – November 10, 2011

2.2.4 Risk Estimates 

The RMEI and population doses and risks calculated by CAP88 for the White Mesa site are 

shown in Table 14. 

Table 14: White Mesa Risk Assessment Results 

Receptor / Impact 

Radon Release (Ci/yr) 

Unitized Maximum Average 

1 1750 1388 

RMEI 

(1500m SSE) 

Dose (mrem/yr) 5.8E-03 1.2E+01 7.0E+00 

LCF Risk (yr-1) 3.1E-09 6.4E-06 3.7E-06 

Population Dose (person-rem/yr) 2.5E-03 5.2E+00 3.0E+00 

LCF Risk (yr-1) 1.6E-08 3.4E-05 2.0E-05 

2.3 Cañon City3

The Cañon City mill, shown in Figure 3, is located approximately two miles south of downtown 

Cañon City in Fremont County, Colorado. The community of Lincoln Park borders the site to 

the north and the housing developments of Dawson Ranch, Wolf Park, and Eagle Heights are 

located along the mill’s western boundary. The 2,500-acre site includes two inactive mills, ore 

stockpile areas, a partially reclaimed tailings pond disposal area (i.e., the old ponds area), and a 

current tailings pond disposal area (i.e., the lined “main impoundment area”). A large portion of 

the site is used to store waste products in the impoundment area. 

 

3

 The description of the Cañon City site was abstracted from various sources, including CDPHE 2007, Cotter 

2010, and ATSDR 2010, while the aerial view of the Cañon City site was obtained from Google Maps. 
WA 1-04, Task 5 19 SC&A – November 10, 2011

Figure 3: Cañon City – Aerial View 

The Cañon City mill, which is owned by the Cotter Corporation, began operations in 1958, 

extracting uranium ore using an alkaline leach process. At that time, the mill was licensed by the 

U.S. Atomic Energy Agency; currently it is licensed by the state of Colorado (Radioactive 

Materials License: Colo. 369-01). In 1979, the facility switched to an acid leach process for 

extracting uranium. Cotter suspended primary operations in 1987, and only limited and 

intermittent processing occurred until the facility resumed operations in 1999 with a modified 

alkaline-leaching capability until 2001. Cotter refabricated the mill circuits between 2002 and 

2005 to operate using an acid process, since March 2006 the mill has been in storage. Current 

accelerated efforts to close down contaminated facilities at the Cañon City site may be aimed at 

clearing a path for possible uranium processing in the future and do not indicate that Cotter plans 

to leave the 2,600-acre site. There is indication that Cotter is planning a $200-million rebuild of 

the mill by 2014, when it expects to treat ore from the Mount Taylor mine in New Mexico. 

2.3.1 Population and Food Production 

The 80-kilometer population distribution in each of the 16 principal compass directions, which 

was calculated for the Cañon City site by SECPOP and used in CAP88 for population dose 
WA 1-04, Task 5 20 SC&A – November 10, 2011

calculations, is shown in Table 15. To adjust the 2000 population data to 2010, the CAP88 

Cañon City population dose was multiplied by 1.04, see Section 1.2 and Table 3. 

Table 15: Cañon City Population Data 

Dir Distance (km) 

0 to 1 1 to 2 2 to 3 3 to 4 4 to 5 5 to 10 

N 0 18 37 915 1198 9911 

NNW 0 0 20 114 1699 1663 

NW 0 0 105 0 20 0 

WNW 0 16 38 0 0 0 

W 0 71 27 0 0 0 

WSW 0 0 0 0 30 0 

SW 0 0 0 0 0 7 

SSW 0 0 0 0 0 0 

S 0 0 0 0 0 0 

SSE 0 0 0 9 0 8 

SE 0 0 0 0 0 32 

ESE 0 0 0 0 0 1484 

E 0 0 0 0 0 2040 

ENE 0 0 0 106 52 2961 

NE 0 0 31 679 295 1939 

NNE 0 0 138 942 1046 4365 

Dir Distance (km) 

20 to 30 30 to 40 40 to 50 50 to 60 60 to 70 70 to 80 

N 4 1310 1083 2224 5576 450 

NNW 4 46 369 347 251 132 

NW 93 61 43 102 55 117 

WNW 0 39 41 41 6061 1261 

W 196 225 315 996 290 901 

WSW 637 136 169 32 249 152 

SW 205 812 106 13 726 134 

SSW 341 737 261 0 98 15 

S 145 5 253 145 180 155 

SSE 295 56 699 1683 754 160 

SE 107 236 506 513 1104 36 

ESE 16 1688 8507 90006 10649 1976 

E 1350 1081 6010 14530 20 84 

ENE 733 12 43 3498 203 578 

NE 7 215 1369 111270 191995 52423 

NNE 38 627 99 15816 66131 34794 

The agricultural productivity factors for Colorado were taken from Appendix C of the CAP88 

User’s Manual, as shown below, and used in the Cañon City site population dose calculation. 

Beef Cattle Density (cattle/km2

): 1.13 

Milk Cattle Density (cow/km2): 0.35 

Land Cultivated for Vegetable Crops: 1.39% 
WA 1-04, Task 5 21 SC&A – November 10, 2011

The distance and direction to the RMEI were identified in the Agency for Toxic Substances and 

Disease Registry’s public health assessment (ATSDR 2010) as: 

The nearest residence is about 0.25 miles from the mill [ATSDR 2010, page 1].

Notice that the Table 15 SECPOP estimate places the nearest individuals to Cañon City at a 

distance of 1 to 2 km in the North, West, and WNW directions. Through analysis using CAP88 

the RMEI was found to be located 1 to 2 km North. To calculate the RMEI dose and risk for this 

study, the Table 15 RMEI distances and directions were used, since the public health assessment 

did not specify the direction to the nearest resident. 

2.3.2 Meteorology 

The CAP88 computer program is provided with a weather library of meteorological data from 

over 350 NWS stations. For the Cañon City site, the CAP88-provided weather data for Colorado 

Springs, CO (CAP88 File: 93037.WND) were used. The period of record for this data included 

the years 1988 through 1992. Table 16 shows the directional dependent average wind speed for 

each stability class, while Table 17 gives the stability class frequency, used in the Cañon City 

analysis. 

Table 16: Cañon City Arithmetic Average Wind Speeds (Wind Towards) 

Dir Pasquill Stability Class (m/s) 

A B C D E F G 

N 1.900 2.710 4.450 5.320 3.570 1.950 0.000 

NNW 1.830 2.880 4.610 5.480 3.760 2.030 0.000 

NW 1.950 2.980 4.310 5.200 3.760 2.070 0.000 

WNW 1.850 2.820 3.760 4.690 3.700 2.020 0.000 

W 1.880 2.360 3.450 4.390 3.650 2.030 0.000 

WSW 1.640 2.190 3.490 4.660 3.550 2.020 0.000 

SW 1.880 2.440 3.220 4.960 3.740 2.230 0.000 

SSW 1.850 2.120 3.970 5.170 3.960 2.300 0.000 

S 2.030 2.030 4.200 6.540 4.010 2.250 0.000 

SSE 1.480 2.340 3.790 7.000 3.940 2.150 0.000 

SE 2.030 2.120 3.590 6.710 3.740 2.080 0.000 

ESE 2.020 2.200 3.320 6.500 3.570 1.930 0.000 

E 1.880 1.870 3.750 6.120 3.470 1.840 0.000 

ENE 1.880 2.330 3.730 6.030 3.470 1.860 0.000 

NE 2.030 2.400 3.480 6.020 3.450 1.840 0.000 

NNE 1.780 2.720 4.200 5.960 3.410 1.860 0.000 
WA 1-04, Task 5 22 SC&A – November 10, 2011

Table 17: Cañon City Frequencies of Stability Classes (Wind Towards) 

Dir Pasquill Stability Class (m/s) 

A B C D E F G

N 0.0116 0.1188 0.2367 0.4935 0.0654 0.0741 0.0000 

NNW 0.0071 0.0907 0.2116 0.5325 0.0851 0.0730 0.0000 

NW 0.0123 0.0988 0.2017 0.4892 0.1146 0.0833 0.0000

WNW 0.0164 0.1108 0.1983 0.3762 0.1622 0.1362 0.0000 

W 0.0154 0.1102 0.1597 0.3290 0.1767 0.2090 0.0000 

WSW 0.0085 0.0823 0.1231 0.3181 0.1974 0.2706 0.0000 

SW 0.0044 0.0474 0.0783 0.2728 0.2647 0.3324 0.0000

SSW 0.0021 0.0220 0.0577 0.2310 0.3668 0.3204 0.0000 

S 0.0021 0.0190 0.0658 0.4320 0.2807 0.2004 0.0000 

SSE 0.0023 0.0226 0.0603 0.6097 0.1893 0.1159 0.0000 

SE 0.0017 0.0307 0.0855 0.5660 0.1750 0.1410 0.0000

ESE 0.0045 0.0585 0.1043 0.5250 0.1552 0.1525 0.0000 

E 0.0108 0.0861 0.1416 0.4909 0.1250 0.1457 0.0000 

ENE 0.0204 0.1346 0.1629 0.4512 0.0858 0.1451 0.0000 

NE 0.0180 0.1876 0.1914 0.4188 0.0725 0.1118 0.0000

NNE 0.0149 0.1415 0.2149 0.4723 0.0712 0.0852 0.0000 

TOTAL 0.0074 0.0678 0.1321 0.4401 0.1863 0.1664 0.0000 

2.3.3 Radon Release 

Cotter Corporation does not include the site’s radon release in its semi-annual effluent reports 

that are prepared for the Colorado Department of Public Health and Environment. However, 

until recently, the reports did include the results of radon flux measurements for the Primary and 

Secondary Impoundments in their semi-annual effluent reports. The radon flux measurements 

can be used to calculate an annual radon release following the guidance provided in Quinn 2010. 

This was done, and the resulting annual radon releases from 1999 through 2009 are tabulated in 

Table 18 and shown graphically in Figure 4. 

Table 18: Cañon City Annual Radon Release 

Year Radon Flux 

(pCi/m2

-s) 

Radon Release 

(Ci/y) 

1999 13.2 180 

2000 7.7 105 

2001 7.9 108 

2002 15.9 217 

2003 5.8 79 

2004 6.2 85 

2005 7.6 104 

2006 6.1 83 

2007 14 191 

2008 19.7 269 

2009 13.4 183 

Sources: Cotter 2007, Figure 4-19; Cain 2008, page 

47; Cain 2010, page 50 
WA 1-04, Task 5 23 SC&A – November 10, 2011

Figure 4: Cañon City Radon Flux and Annual Release

Although the radon releases given in Table 18 and Figure 4 are only from the impoundments, it 

is assumed that other onsite sources of radon would be small by comparison. The basis for this 

assumption is that no milling operations have occurred at Cañon City since 2005, and there is not 

likely much uranium onsite to act as a source of radon. This is supported by the monthly release 

rates for uranium, thorium, and radium, which are very low. Finally, Cotter 2010 points out that 

the offsite radon daughter (i.e., 210Pb) concentrations (which are measured and reported in the 

semiannual effluent reports) are consistent with what would be expected from non-Cañon City 

Milling Facility radon: 

Results for 210Pb at all monitoring locations are controlled by regional 222Rn 

concentrations and do not exhibit discernible effects from milling facility activities. 

[Cotter 2010, page 5-4] 

2.3.4 Risk Estimates 

The RMEI and population doses and risks calculated by CAP88 for the Cañon City site are 

shown in Table 19. 
WA 1-04, Task 5 24 SC&A – November 10, 2011

Table 19: Cañon City Risk Assessment Results 

Receptor / Impact 

Radon Release (Ci/yr) 

Unitized Maximum Average 

1 269 146 

RMEI 

(1500m N) 

Dose (mrem/yr) 5.0E-03 1.0E+01 6.0E+00 

LCF Risk (yr-1) 2.6E-09 5.4E-06 3.1E-06 

Population Dose (person-rem/yr) 2.4E-02 4.9E+01 2.9E+01 

LCF Risk (yr-1) 1.5E-07 3.1E-04 1.8E-04 

2.4 Smith Ranch – Highland4

Power Resources Incorporated (PRI), a wholly owned subsidiary of the Cameco Corporation, 

operates the Highland and Smith Ranch ISL uranium mines located in eastern Wyoming, 

approximately 16 miles north of Glenrock in Converse County. In 1987, ISL facilities were 

constructed at the Highland mine, and commercial production began a year later. Cameco 

acquired PRI in 1997. The first ISL pilot operation began in 1981 at the Smith Ranch; the 

second operation began in 1984. Commercial ISL facilities were constructed in 1996 and began 

producing a year later. Cameco then acquired the Smith Ranch from Rio Algom Mining 

Corporation in 2002 and consolidated the Highland and Smith Ranch operations (the Highland 

license, SUA-1511, was integrated into the license: SUA-1548). The Highland and Smith Ranch 

mines are currently the largest operated uranium production facilities in the United States, with 

lifetime production capacities of two million pounds of uranium from each facility. Proven and 

probable reserves total 5.9 million pounds of U3O8, and in 2009, production was 1.8 million 

pounds of U3O8. 

The permit area for the combined Smith Ranch – Highland properties contains 30,760 acres. 

The main facilities at the Smith Ranch – Highland Uranium Project (SR-HUP), besides the well 

fields, include the two yellowcake processing plant sites and related facilities that are located 

within the former Bill Smith Mine site (Smith Ranch Main Office Central Processing Plant 

[CPP] Complex) and the former Exxon Highland Mine site (HUP Central Plant/Office 

Complex). Since 2002, the HUP facilities have been on stand-by status, although in the future it 

may be used as a resin stripping, elution, and precipitation facility. All yellowcake processing, 

office, and related activities currently are occurring at Smith Ranch, shown in Figure 5. In 

association with the Smith Ranch CPP is a lined, two-celled evaporation pond to assist with 

wastewater disposal. Additional lined evaporation ponds consisting of 5- to 15-acre cells may be 

constructed as needed. Waste water is also disposed at two deep disposal wells at Smith Ranch 

and one deep disposal well at Highland. 

 

4

 The description of the Smith Ranch – Highland site was abstracted from various sources, including RAMC 

1999, Trihydro 2005, Melbye 2008, Cameco 2009, and Cameco 2010b, while the aerial view of the Smith 

Ranch – Highland site was obtained from Google Maps. 
WA 1-04, Task 5 25 SC&A – November 10, 2011

Figure 5: Smith Ranch – Aerial View 

2.4.1 Population and Food Production 

The 80-kilometer population distribution in each of the 16 principal compass directions, which 

was calculated for the Smith Ranch – Highland site by SECPOP and used in CAP88 for 

population dose calculations, is shown in Table 20. To adjust the 2000 population data to 2010, 

the CAP88 Smith Ranch – Highland population dose was multiplied by 1.14, see Section 1.2 and 

Table 3. 

Table 20: Smith Ranch – Highland Population Data 

Dir Distance (km) 

0 to 1 1 to 2 2 to 3 3 to 4 4 to 5 5 to 10 10 to 20

N 0 0 0 0 0 0 10 

NNW 0 0 0 0 0 0 0 

NW 0 0 0 0 0 0 0 

WNW 0 0 0 0 0 0 0 

W 0 0 0 0 0 0 0 

WSW 0 0 0 0 0 0 6 

SW 0 0 0 0 0 0 33 

SSW 0 0 0 0 0 0 133 

S 0 0 0 0 0 0 19 

SSE 0 0 0 0 0 0 0 

SE 0 0 0 0 0 0 9 

ESE 0 0 0 0 0 0 0 

E 0 0 0 0 0 2 0 

ENE 0 0 0 0 0 0 0 

NE 0 0 0 0 0 0 4 

NNE 0 0 0 0 0 0 6 
WA 1-04, Task 5 26 SC&A – November 10, 2011

Table 20: Smith Ranch – Highland Population Data 

Dir Distance (km) 

20 to 30 30 to 40 40 to 50 50 to 60 60 to 70 70 to 80 

N 7 5 13 30 4 172 

NNW 2 3 14 10 10 11 

NW 0 0 0 17 590 31 

WNW 0 0 13 3 6 2 

W 0 0 2 304 24 123 

WSW 37 216 926 42155 20374 756 

SW 2418 137 179 63 66 32 

SSW 893 25 27 5 0 0 

S 80 37 33 6 5 4 

SSE 77 388 586 88 35 63 

SE 19 1234 5161 78 106 54 

ESE 16 5 21 29 22 44 

E 5 8 5 16 20 13 

ENE 0 21 30 3 21 12 

NE 9 0 14 14 4 19 

NNE 4 14 9 3 33 1299 

The agricultural productivity factors for Wyoming were taken from Appendix C of the CAP88 

User’s Manual, as shown below, and used in the Smith Ranch – Highland site population dose 

calculation. 

Beef Cattle Density (cattle/km2): 5.12 

Milk Cattle Density (cow/km2

): 0.0579 

Land Cultivated for Vegetable Crops: 0.159% 

The distance and direction to the RMEI were identified in the Smith Ranch – Highland license 

application (PRI 2003) as: 

... the Sundquist (Smith) Ranch located approximately 2.6 miles southwest of the Smith 

Ranch Main Office/CPP site, the Vollman Ranch well located approximately 1.5 miles 

east of Satellite No. 3 and the Fowler Ranch well located just north of the permit area 

approximately 2.5 miles north of the Highland Central Plant. [PRI 2003, page 2-3] 

Notice, that the Table 20 SECPOP estimate places the nearest individual to Smith Ranch – 

Highland at a distance of 5 to 10 km in the East direction. This location was found through 

analysis using CAP88 to be the location of the RMEI. To calculate the RMEI dose and risk for 

this study, the Table 20 RMEI distance and direction were used. 

2.4.2 Meteorology 

The CAP88 computer program is provided with a weather library of meteorological data from 

over 350 NWS stations. For the Smith Ranch – Highland site, the CAP88-provided weather data 

for Casper, WY (CAP88 File: CPR0335.WND) were used. The period of record for this data 

included the years 1967 through 1971. Table 21 shows the directional dependent average wind 
WA 1-04, Task 5 27 SC&A – November 10, 2011

speed for each stability class, while Table 22 gives the stability class frequency used in the Smith 

Ranch – Highland analysis. 

Table 21: Smith Ranch – Highland Arithmetic Average Wind Speeds 

(Wind Towards) 

Dir Pasquill Stability Class (m/s) 

A B C D E F G 

N 1.372 2.360 3.774 5.971 3.088 1.804 0.000 

NNW 1.855 2.243 3.408 4.058 3.145 1.862 0.000 

NW 1.972 2.493 3.522 4.613 3.354 2.059 0.000 

WNW 1.991 2.361 3.922 5.109 3.762 1.924 0.000 

W 1.585 2.354 3.613 5.489 3.668 2.019 0.000 

WSW 1.178 2.558 3.731 4.958 3.653 2.147 0.000 

SW 1.991 2.901 3.740 5.331 3.461 2.056 0.000 

SSW 1.725 2.656 3.756 5.648 3.423 2.160 0.000 

S 1.972 2.687 3.938 5.565 3.384 1.943 0.000 

SSE 1.991 2.699 4.561 4.794 3.367 2.064 0.000 

SE 0.772 3.216 3.909 6.086 3.344 2.104 0.000 

ESE 1.972 2.827 4.075 6.414 3.521 2.041 0.000 

E 1.837 2.846 4.651 6.724 3.865 2.010 0.000 

ENE 1.725 2.973 4.670 7.288 4.105 2.073 0.000 

NE 1.178 2.691 5.089 8.261 4.040 1.959 0.000 

NNE 1.672 2.809 4.477 8.494 3.971 1.924 0.000 

Table 22: Smith Ranch – Highland Frequencies of Stability Classes 

(Wind Towards) 

Dir Pasquill Stability Class (frequency) 

A B C D E F G

N 0.0093 0.1614 0.1547 0.4633 0.0849 0.1264 0.0000 

NNW 0.0904 0.1825 0.1474 0.3184 0.1325 0.1289 0.0000 

NW 0.0115 0.1378 0.1499 0.4327 0.1466 0.1214 0.0000

WNW 0.0109 0.0631 0.1201 0.5322 0.1641 0.1095 0.0000 

W 0.0067 0.0608 0.1044 0.5708 0.1438 0.1135 0.0000 

WSW 0.0092 0.0366 0.0886 0.5864 0.1417 0.1376 0.0000 

SW 0.0072 0.0404 0.0644 0.6413 0.1314 0.1152 0.0000

SSW 0.0084 0.0388 0.0585 0.6700 0.1046 0.1197 0.0000 

S 0.0037 0.0385 0.0691 0.5697 0.1331 0.1860 0.0000 

SSE 0.0084 0.0694 0.0792 0.4323 0.1598 0.2509 0.0000 

SE 0.0061 0.0442 0.0914 0.4621 0.1687 0.2275 0.0000

ESE 0.0109 0.0439 0.0937 0.4982 0.1641 0.1892 0.0000 

E 0.0081 0.0372 0.0843 0.4802 0.2302 0.1600 0.0000 

ENE 0.0031 0.0175 0.0636 0.6527 0.1984 0.0647 0.0000 

NE 0.0017 0.0165 0.0400 0.8454 0.0730 0.0233 0.0000

NNE 0.0044 0.0224 0.0438 0.8422 0.0546 0.0327 0.0000 

TOTAL 0.0066 0.0389 0.0717 0.6385 0.1394 0.1049 0.0000 
WA 1-04, Task 5 28 SC&A – November 10, 2011

2.4.3 Radon Release 

Tables 3 and 4 of Savignac 2007 provide the data necessary to use NUREG-1569 (NRC 2003), 

Appendix D to calculate the radon released from the various Smith Ranch – Highland well fields 

during both production and restoration, respectively. Using the Savignac 2007 data, Table 23 

presents the calculated well field annual radon releases during both production and restoration. 

The reason that the annual restoration radon release is greater than the production release for all 

the well fields, except well field SW, is because the restoration purge rate is greater. Thus, there 

is less time for radiological decay to reduce the amount of radon prior to its release. 

Table 23: Smith Ranch – Highland Well Field Annual Radon Release 

Well Field 

Radon Release (Ci/yr) 

Production Restoration 

Purge Vent IX Total Purge Vent Total 

C 19 1,544 2.3 1,565 157 1,537 1,694

D 6 257 2.3 266 26 256 282

Dext 4 772 2.3 779 79 768 848

E 2 1,011 2.3 1,016 103 1,006 1,109

F 8 4,230 2.3 4,241 455 4,207 4,662

H 1 2,207 2.3 2,210 225 2,195 2,420

I 28 2,206 2.3 2,236 225 2,195 2,420

1 185 983 8.7 1,177 794 952 1,745

2 126 674 3.4 803 217 669 886

3 237 1,275 6.9 1,518 806 1,245 2,051

4/4A 185 1,001 8.2 1,195 334 994 1,328

(SR)15 62 2,572 2.3 2,636 239 2,562 2,801

(SR)15A 58 2,388 2.2 2,448 206 2,380 2,586

(HUP)J 40 2,389 2.2 2,431 245 2,378 2,624

(HUP)K 41 844 2.4 887 94 841 935

SW 4,727 3,615 1.1 8,343 311 3,846 4,157

Cameco 2009 presents a revised estimated schedule for Smith Ranch – Highland well field 

activities, which has been reproduced below as Figure 6. 
WA 1-04, Task 5 29 SC&A – November 10, 2011

Figure 6: Smith Ranch – Highland – Estimated Time Table of Mining Related Activities 

Figure 6 is used in conjunction with Table 23 to calculate the site-wide annual radon release over 

the Smith Ranch – Highlands estimated operating life. Figure 7 shows these calculated Smith 

Ranch – Highland radon releases. 
WA 1-04, Task 5 30 SC&A – November 10, 2011

Figure 7: Smith Ranch – Highland – Total Estimated Radon Release by Year 

The calculated maximum Smith Ranch – Highland annual radon release from all well fields 

either in production or restoration occurs in 2009 and is 36,500 Ci, while the average annual 

radon release from 2009 to 2029 is 21,100 Ci. 

2.4.4 Risk Estimates 

The RMEI and population doses and risks calculated by CAP88 for the Smith Ranch – Highland 

site are shown in Table 24. 

Table 24: Smith Ranch – Highland Risk Assessment Results 

Receptor / Impact 

Radon Release (Ci/yr) 

Unitized Maximum Average 

1 36,500 21,100 

RMEI 

(7500m E) 

Dose (mrem/yr) 7.2E-04 1.5E+00 8.6E-01 

LCF Risk (yr-1) 3.7E-10 7.7E-07 4.5E-07 

Population Dose (person-rem/yr) 1.8E-03 3.7E+00 2.2E+00 

LCF Risk (yr-1) 1.1E-08 2.3E-05 1.3E-05 
WA 1-04, Task 5 31 SC&A – November 10, 2011

2.5 Crow Butte5

The Crow Butte Project site is located in west central Dawes County, Nebraska, just north and 

west of the Pine Ridge Area. The Crow Butte Project site, shown in Figure 8, is about 4.0 miles 

southeast of the City of Crawford via Squaw Creek Road. What is now the Crow Butte Project 

was originally developed by Wyoming Fuel Corporation, which constructed a R&D facility at 

the site in 1986; commercial operations began in 1991. The project was subsequently acquired 

and is now owned and operated by Crow Butte Resources, Inc. (CBR), known as the Ferret 

Exploration Company of Nebraska until May 1994. It is the first uranium mine in Nebraska and 

has reserves of 5.9 million pounds of U3O8 (2,270 tonnes U), resources of 8.5 million pounds of 

U3O8 (3,270 tonnes U), and an annual capacity of 2 million pounds of U3O8. 

Figure 8: Crow Butte – Aerial View 

Most of the following description of the Crow Butte ISL process was taken from the license 

renewal application (CBR 2007). Uranium is recovered by ISL from the Chadron Sandstone at a 

depth that varies from 400 feet to 900 feet. The overall width of the mineralized area varies from 

1000 feet to 5000 feet. The ore body ranges from less than 0.05 percent to greater than 0.5 

percent U3O8, with an average grade estimated at 0.26 percent equivalent U3O8. The ISL process 

at Crow Butte uses gaseous oxygen or hydrogen peroxide to oxidize the uranium, and 

bicarbonate for dissolution. The uranium-bearing solution that results from the leaching of 

uranium underground is recovered from the well field and the uranium is extracted in the process 

plant. The plant process consists of the following steps: 

• Loading of uranium complexes onto ion exchange resin; 

• Reconstitution of the solution by the addition of carbonate and an oxidizer; 

 

5

 The description of the Crow Butte site was abstracted from various sources, including CBR 2007, Melbye 2008, 

CBR 2009, and Cameco 2010a, while the aerial view of the Crow Butte site was obtained from Google Maps. 
WA 1-04, Task 5 32 SC&A – November 10, 2011

• Elution of the uranium complexes from the resin; and 

• Drying and packaging of the uranium. 

The radon-222 is contained in the pregnant lixiviant that comes from the well field to the process 

plant. The majority of this radon is released in the ion exchange columns and process tanks. 

These vessels are covered and vented to a manifold, which are in turn exhausted to atmosphere 

outside the building through stacks. 

2.5.1 Population and Food Production 

The 80-kilometer population distribution in each of the 16 principal compass directions, which 

was calculated for the Crow Butte site by SECPOP and used in CAP88 for population dose 

calculations, is shown in Table 25. To adjust the 2000 population data to 2010, the CAP88 Crow 

Butte population dose was multiplied by 0.96, see Section 1.2 and Table 3. 

Table 25: Crow Butte Population Data 

Dir Distance (km) 

0 to 1 1 to 2 2 to 3 3 to 4 4 to 5 5 to 10 10 to 20

N 0 0 0 0 0 19 20 

NNW 0 0 0 1 0 34 39 

NW 0 0 0 1 0 1140 33 

WNW 0 0 4 0 0 20 12 

W 0 3 0 0 0 24 20 

WSW 0 2 0 5 0 7 21 

SW 0 0 0 6 0 0 25 

SSW 0 0 0 0 1 10 18 

S 0 0 0 0 0 0 41 

SSE 0 0 0 0 12 0 22 

SE 0 0 0 0 0 10 12 

ESE 0 1 0 0 0 0 43 

E 0 0 0 0 0 0 6 

ENE 0 0 0 15 0 9 32 

NE 0 0 0 0 0 7 42 

NNE 0 0 0 0 0 5 147 
WA 1-04, Task 5 33 SC&A – November 10, 2011

Table 25: Crow Butte Population Data 

Dir Distance (km) 

20 to 30 30 to 40 40 to 50 50 to 60 60 to 70 70 to 80 

N 0 3 22 88 187 232 

NNW 3 7 13 22 37 80 

NW 26 24 4 23 0 51 

WNW 25 35 22 22 28 37 

W 27 26 295 35 72 25 

WSW 22 8 9 29 35 34 

SW 13 7 46 14 14 26 

SSW 17 14 22 12 88 355 

S 29 42 40 34 8 239 

SSE 37 80 1148 209 268 5496 

SE 14 94 134 182 495 3841 

ESE 43 60 35 178 131 70 

E 70 263 101 889 162 1193 

ENE 203 598 101 86 109 3858 

NE 59 5588 55 29 166 1904 

NNE 1 17 11 17 81 103 

The agricultural productivity factors for Nebraska were taken from Appendix C of the CAP88 

User’s Manual, as shown below, and used in the Crow Butte site population dose calculation. 

Beef Cattle Density (cattle/km2): 35. 

Milk Cattle Density (cow/km2): 0.878 

Land Cultivated for Vegetable Crops: 2.39% 

The distance and direction to the RMEI were identified in the CBR’s response to NRC’s request 

for additional information (RAI) (CBR 2009) regarding the Crow Butte license renewal 

application as: 

Two dwelling units are within 0.62 mile [ENE and ESE], and another five dwelling units 

are within 1.24 miles of the center point of the License Area. [CBR 2009, Section 

2.2.3.4] 

Notice that the Table 25 SECPOP estimate places the nearest individuals to Crow Butte at a 

distance of 1 to 2 km in the West, WSW, and ESE directions. Through analysis using CAP88 the 

RMEI was found to be located 1 to 2 km in the WSW direction. To calculate the RMEI dose and 

risk for this study, the Table 25 RMEI distances and directions were used, since they are 

consistent with the RAI response information (i.e., 0.62 mile is equal to 1 km in the ESE 

direction, and 1.24 miles is about 2 km). 

2.5.2 Meteorology 

The Crow Butte ISL site has a meteorological monitoring station that records wind speed, wind 

direction, and stability class. This onsite meteorological data were used by CBR to formulate a 

joint frequency distribution for the dose calculations performed as part of the Crow Butte license 
WA 1-04, Task 5 34 SC&A – November 10, 2011

renewal application. For this risk assessment, the meteorological data from the license renewal 

application were reformatted so that it could be processed by the CAP88 auxiliary program, 

WINDGET (Trinity 2007), which generated a meteorological data file in the format required by 

CAP88 (i.e., a .WND file). Table 26 shows the directional-dependent average wind speed for 

each stability class that was used in this risk assessment for the Crow Butte site, while Table 27 

gives the stability class frequency. 

Table 26: Crow Butte Arithmetic Average Wind Speeds (Wind Towards) 

Dir Pasquill Stability Class (m/s) 

A B C D E F G 

N 3.702 5.309 5.269 8.323 3.824 2.504 0.000 

NNW 4.259 5.031 7.395 7.497 3.340 2.364 0.000 

NW 3.890 5.313 6.946 6.680 3.971 2.243 0.000 

WNW 3.251 4.099 6.033 5.610 3.801 1.897 0.000 

W 3.208 4.558 6.026 6.968 3.559 1.643 0.000 

WSW 3.400 4.658 6.596 6.267 3.786 1.869 0.000 

SW 3.381 4.672 6.051 6.886 3.936 2.446 0.000 

SSW 3.594 4.399 5.726 7.469 3.882 2.095 0.000 

S 3.844 5.053 5.848 6.572 3.401 1.826 0.000 

SSE 3.898 5.988 5.852 8.053 3.356 1.682 0.000 

SE 4.106 5.996 5.821 9.384 4.293 2.160 0.000 

ESE 4.322 4.833 5.447 8.553 4.029 2.311 0.000 

E 4.296 5.217 5.643 8.225 3.246 2.105 0.000 

ENE 4.024 5.198 4.985 7.496 4.094 2.192 0.000 

NE 3.804 4.493 5.118 6.580 4.179 2.347 0.000 

NNE 4.550 4.719 4.820 7.136 3.594 2.568 0.000 
WA 1-04, Task 5 35 SC&A – November 10, 2011

Table 27: Crow Butte Frequencies of Stability Classes (Wind Towards) 

Dir Pasquill Stability Class (frequency) 

A B C D E F G

N 0.0229 0.0336 0.0608 0.5833 0.1758 0.1236 0.0000 

NNW 0.0349 0.0462 0.0908 0.5105 0.2089 0.1087 0.0000 

NW 0.0885 0.1017 0.1610 0.3487 0.1788 0.1213 0.0000

WNW 0.0605 0.1256 0.1596 0.2897 0.1589 0.2058 0.0000 

W 0.1169 0.0716 0.4700 0.1658 0.0878 0.0879 0.0000 

WSW 0.1062 0.1419 0.2329 0.3233 0.1250 0.0708 0.0000 

SW 0.0833 0.1149 0.1570 0.4925 0.1229 0.0294 0.0000

SSW 0.1098 0.0898 0.1157 0.5296 0.1157 0.0395 0.0000 

S 0.1463 0.1528 0.1463 0.3110 0.1425 0.1010 0.0000 

SSE 0.0825 0.1194 0.1369 0.5582 0.0695 0.0335 0.0000 

SE 0.0332 0.0615 0.0780 0.7436 0.0521 0.0315 0.0000

ESE 0.0677 0.1026 0.0720 0.5913 0.1089 0.0574 0.0000 

E 0.0823 0.1161 0.1263 0.4623 0.1055 0.1075 0.0000 

ENE 0.0372 0.0696 0.1450 0.5163 0.1518 0.0801 0.0000 

NE 0.0281 0.0439 0.0930 0.5189 0.1994 0.1166 0.0000

NNE 0.0244 0.0400 0.0874 0.4574 0.2123 0.1785 0.0000 

TOTAL 0.0559 0.0730 0.1152 0.5100 0.1510 0.0948 0.0000 

2.5.3 Radon Release 

Regarding radon release from the Crow Butte site, the application for license renewal (CBR 

2007) stated: 

The only radioactive airborne effluent at the Crow Butte Project is radon-222 gas. As 

yellowcake drying and packaging is carried out using a vacuum dryer, there are no 

airborne effluents from that system. 

The radon-222 is contained in the pregnant lixiviant that comes from the wellfield to the 

process plant. The majority of this radon is released in the ion exchange columns and 

process tanks. These vessels are covered and vented to a manifold, which are in turn 

exhausted to atmosphere outside the building through stacks. The manifolds are 

equipped with an exhausting fan. [CBR 2007, Section 1.8.1] 

As required by 10 CFR § 40.65 and License SUA-1534 Condition Number 12.1, the estimated 

release of radon from process operations is reported in the semi-annual reports. Table 28 

contains annual calculated radon releases from the Crow Butte Project Facility since 1994, as 

does Figure 9. 
WA 1-04, Task 5 36 SC&A – November 10, 2011

Table 28: Crow Butte Radon 

Release to the Environment 

Year Release 

(Ci/yr) Year Release (Ci/yr) 

1995 3,537 2001 4,633 

1996 3,997 2002 4,675 

1997 4,175 2003 4,615 

1998 4,740 2004 4,671 

1999 4,674 2005 4,517 

2000 4,760 2006 4,607 

Source: CBR 2009, Table 5.8-8 

Table 29: Crow Butte Modeled 

Radon Release 

Source Release 

(Ci/yr) 

Plant Vent 4,603 

Satellite Plant Vent 342 

MU-2-4 (restoration) 350 

MU-5 454 

MU-6&8 908 

MU 7&9 908 

North Trend Well Field 1,320 

Total 8,885 

Source: CBR 2007, Table 7.12-5 

CBR 2007 used MILDOS-Area to model the emission rate of radon from the Crow Butte Project, 

including the North Trend Well Field. Those modeled radon emission rates are shown in Table 

29, which consists of a flow of 5000 gpm in the up-flow ion exchange columns in the existing 

plant, along with the proposed 4000 gpm of flow treated in the pressurized down-flow ion 

exchange columns. Notice that the modeled radon release rate is about twice as that reported as 

the estimated radon release rate. 

Figure 9: Crow Butte Total Estimated Semi-Annual Radon Release 

(1991-2007) 

For the Crow Butte Project, the maximum annual radon release rate was assumed to be 8,885 Ci, 

while the average annual release rate is 4,467 Ci. 
WA 1-04, Task 5 37 SC&A – November 10, 2011

2.5.4 Risk Estimates 

The RMEI and population doses and risks calculated by CAP88 for the Crow Butte site are 

shown in Table 30. 

Table 30: Crow Butte Risk Assessment Results 

Receptor / Impact 

Radon Release (Ci/yr) 

Unitized Maximum Average 

1 8,885 4,467 

RMEI 

(1500m WSW) 

Dose (mrem/yr) 1.6E-03 3.3E+00 1.9E+00 

LCF Risk (yr-1) 8.4E-10 1.7E-06 1.0E-06 

Population Dose (person-rem/yr) 1.3E-03 2.7E+00 1.6E+00 

LCF Risk (yr-1) 8.4E-09 1.7E-05 1.0E-05 

2.6 Christensen / Irigaray6

The Christensen / Irigaray Ranch project is an ISL uranium mining operation located 

approximately 55 miles southeast of Buffalo, Wyoming, and 51 miles northeast of Midwest, 

Wyoming. The project is actually composed of two ISL sites (7 miles apart) containing well 

fields or facilities within approximately 687 acres. The first area, generally referred to as the 

Irigaray site or the Irigaray CPP, is located in southeast Johnson County, Wyoming (see Figure 

10). The uranium deposit is one of many located in the Powder River Basin in northeast 

Wyoming. The property consists of approximately twenty-eight square miles. The second area 

is the Christensen Ranch well field and satellite operation (ion exchange plant), shown in Figure 

11, which is located approximately 13 miles southeast of the Irigaray site. The Christensen 

Ranch operations consist of approximately 14,000 acres in Johnson and Campbell Counties, 

Wyoming. 

In August 1978, the NRC issued one license, SUA-1341, which covers both areas of the 

Christensen / Irigaray Ranch project. The site operated intermittently until June 2000, when all 

mining activities were suspended due to low uranium prices. In April 2007, the mine owner, 

Cogema Mining, Inc., requested an amendment to the license to return the facility to an operating 

status. The NRC subsequently approved the licensee’s request by a license amendment dated 

September 30, 2008. In December 2009, Cogema Mining was sold to Uranium One, Inc. 

In anticipation of plant startup, the licensee began implementing operations-related 

environmental monitoring during October 2008. When the plant resumes operation, the first 

mine unit that will be placed into service will be Christensen Ranch mine unit 7. At the time of 

the inspection, the well field data package for this mine unit was being reviewed by the State of 

Wyoming. The construction of the mine unit was approximately half complete. The monitor 

 

6

 The description of the Christensen / Irigaray site was abstracted from various sources, including Melbye 2008, 

NRC 2008, and NRC 2010, while the aerial views of the Christensen / Irigaray site were obtained from Google 

Maps. 
WA 1-04, Task 5 38 SC&A – November 10, 2011

well ring and some of the main trunk lines had been installed. In the near future, the licensee 

plans to develop Christensen Ranch mine units 8-9. Future well fields may include Christensen 

Ranch mine units 10-12. 

Since the site was returned to operational status September 30, 2008, with the intent of returning 

to uranium production, plans to decommission the CPP at Irigaray were stopped, and, instead, 

the plant will be refurbished for a return to operation. Surface reclamation of the well fields at 

Irigaray will continue, as there is no intent to reopen them for production. The satellite 

processing plant at Christensen Ranch will be used for operations, as uranium production has not 

occurred at several permitted well fields at Christensen Ranch. The Irigaray CPP may also be 

used for final processing of uranium from the Moore Ranch and Uranium One’s other uranium 

projects in the Powder River Basin. 

Figure 10: Irigaray – Aerial View 
WA 1-04, Task 5 39 SC&A – November 10, 2011

Figure 11: Christensen – Aerial View 

2.6.1 Population and Food Production 

The 80-kilometer population distribution in each of the 16 principal compass directions, which 

was calculated for the Christensen / Irigaray site by SECPOP and used in CAP88 for population 

dose calculations, is shown in Table 31. To adjust the 2000 population data to 2010, the CAP88 

Christensen / Irigaray population dose was multiplied by 1.34, see Section 1.2 and Table 3. 

Table 31: Christensen / Irigaray Population Data 

Dir Distance (km) 

0 to 1 1 to 2 2 to 3 3 to 4 4 to 5 5 to 10 10 to 20

N 0 0 0 0 0 0 0 

NNW 0 0 0 0 0 0 0 

NW 0 0 0 0 0 0 6 

WNW 0 0 0 0 0 0 7 

W 0 0 0 0 0 0 0 

WSW 0 0 0 0 0 0 30 

SW 0 0 0 0 0 0 0 

SSW 0 0 0 0 0 0 0 

S 0 0 0 0 0 0 0 

SSE 0 0 0 0 0 1 10 

SE 0 0 0 1 0 0 0 

ESE 0 0 0 0 0 3 5 

E 0 0 0 0 0 0 1 

ENE 0 0 0 0 0 0 7 

NE 0 0 0 0 0 0 0 

NNE 0 0 0 0 0 0 7 
WA 1-04, Task 5 40 SC&A – November 10, 2011

Table 31: Christensen / Irigaray Population Data 

Dir Distance (km) 

20 to 30 30 to 40 40 to 50 50 to 60 60 to 70 70 to 80 

N 0 0 12 18 17 8 

NNW 0 0 3 5 24 16 

NW 0 0 0 26 151 2135 

WNW 0 0 0 16 36 34 

W 0 24 109 39 23 27 

WSW 54 24 277 55 19 13 

SW 4 0 11 0 21 8 

SSW 34 3 600 2 13 0 

S 14 4 0 3 8 0 

SSE 2 0 20 5 4 25 

SE 0 8 29 9 17 14 

ESE 13 7 77 7 5 49 

E 3 0 1417 91 20 8 

ENE 31 2 39 52 16 28 

NE 38 11 150 459 23517 5049 

NNE 0 8 66 407 403 118 

The agricultural productivity factors for Wyoming were taken from Appendix C of the CAP88 

User’s Manual, as shown below, and used in the Christensen / Irigaray site population dose 

calculation. 

Beef Cattle Density (cattle/km2): 5.12 

Milk Cattle Density (cow/km2): 0.0579 

Land Cultivated for Vegetable Crops: 0.159% 

The distance and direction to the RMEI were identified in Cogema’s response to NRC’s RAI 

(Cogema 2010) regarding the Christensen / Irigaray license renewal application as: 

The nearest residence to the IR site is 4 miles to the north (the Brubaker ranch) and the 

nearest residence to CR is the John Christensen ranch located 3 miles southeast of the CR 

plant site. Both are ranch housing with a population of 5 or less. [Cogema 2010, Section 

5.2] 

Notice that the Table 31 SECPOP estimate places the nearest individual to Christensen / Irigaray 

at a distance of 3 to 4 km in the SE direction. This location was found to be the location of the 

RMEI through analysis using CAP88. Since it is slightly closer, the Table 31 RMEI distance and 

direction were used to calculate the RMEI dose and risk for this study. 

2.6.2 Meteorology 

The CAP88 computer program is provided with a weather library of meteorological data from 

over 350 NWS stations. For the Christensen / Irigaray site, the CAP88-provided weather data 

for Casper, WY (CAP88 File: 24089.WND) were used. The period of record for this data 
WA 1-04, Task 5 41 SC&A – November 10, 2011

included the years 1988 through 1992. Table 32 shows the directional-dependent average wind 

speed for each stability class, while Table 33 gives the stability class frequency, used in the 

Christensen / Irigaray analysis. 

Table 32: Christensen / Irigaray Arithmetic Average Wind Speeds 

(Wind Towards) 

Dir Pasquill Stability Class (m/s) 

A B C D E F G 

N 2.070 2.820 4.040 5.620 3.160 1.960 0.000 

NNW 2.080 2.760 3.260 4.620 3.160 1.920 0.000 

NW 1.990 2.920 3.340 4.670 3.160 1.820 0.000 

WNW 2.210 2.650 4.080 5.340 3.580 2.150 0.000 

W 1.940 2.680 4.100 5.730 3.780 2.080 0.000 

WSW 2.070 3.020 4.050 5.110 3.520 2.120 0.000 

SW 1.930 2.990 3.830 5.190 3.410 2.170 0.000 

SSW 2.060 2.870 3.750 5.830 3.520 2.180 0.000 

S 1.770 2.900 3.970 5.510 3.450 2.150 0.000 

SSE 2.190 2.520 3.530 5.120 3.270 2.150 0.000 

SE 2.270 3.030 4.100 5.560 3.470 2.200 0.000 

ESE 2.070 3.110 4.560 6.220 3.450 2.190 0.000 

E 2.020 2.890 4.720 6.500 3.820 2.150 0.000 

ENE 1.970 3.100 5.200 7.080 4.100 2.200 0.000 

NE 2.170 2.980 5.500 8.420 4.010 2.210 0.000 

NNE 1.970 2.990 5.000 8.290 3.740 2.110 0.000 

Table 33: Christensen / Irigaray Frequencies of Stability Classes 

(Wind Towards) 

Dir Pasquill Stability Class (frequency) 

A B C D E F G

N 0.0135 0.2097 0.1742 0.3958 0.0973 0.1095 0.0000 

NNW 0.0276 0.2452 0.2063 0.2690 0.1188 0.1331 0.0000 

NW 0.0302 0.1927 0.2094 0.3469 0.1073 0.1134 0.0000

WNW 0.0083 0.1102 0.1352 0.4937 0.1515 0.1010 0.0000 

W 0.0036 0.0671 0.1110 0.5846 0.1395 0.0943 0.0000 

WSW 0.0088 0.0549 0.0995 0.5699 0.1414 0.1254 0.0000 

SW 0.0061 0.0557 0.0861 0.5939 0.1350 0.1232 0.0000

SSW 0.0056 0.0431 0.0616 0.6628 0.1138 0.1130 0.0000 

S 0.0061 0.0469 0.0886 0.5403 0.1474 0.1707 0.0000 

SSE 0.0046 0.0541 0.0913 0.3999 0.2038 0.2462 0.0000 

SE 0.0015 0.0535 0.0963 0.4190 0.1955 0.2343 0.0000

ESE 0.0063 0.0391 0.1045 0.4612 0.1511 0.2379 0.0000 

E 0.0028 0.0336 0.0921 0.4964 0.2166 0.1586 0.0000 

ENE 0.0013 0.0178 0.0720 0.6031 0.2275 0.0783 0.0000 

NE 0.0008 0.0099 0.0444 0.8381 0.0813 0.0254 0.0000

NNE 0.0028 0.0318 0.0732 0.7946 0.0614 0.0361 0.0000 

TOTAL 0.0041 0.0424 0.0820 0.6227 0.1437 0.1051 0.0000 
WA 1-04, Task 5 42 SC&A – November 10, 2011

2.6.3 Radon Release 

Table 34 presents annual calculated radon release estimates for the Christensen / Irigaray site for 

the period 1995 to 2000, the last production run prior to entering exclusively into restoration. 

Table 34 summarizes the information presented in the semi-annual effluent reports over that time 

period. Calculation of the semi-annual radon release was suspended after year 2000 (Cogema 

2008). 

The source terms used to estimate radon-222 releases from the facility include two well fields in 

production, two restoration well fields, one new well field, and the satellite processing facility. 

The radon-222 releases from these source terms are calculated using methods similar to those 

described in NUREG-1569, Appendix D. For the Christensen Ranch area, mine units 10-12 and 

7 were chosen based on their proximity to site boundaries and predominant wind directions. A 

summary of estimated radon-222 releases from the Facility is presented in Table 35. 

Table 34: Christensen / Irigaray 

Environmental Radon Release Summary 

Year Radon Release (Ci/yr) 

Irigaray Christensen Ranch 

1995 58.5 739.8 

1996 63.9 1125.1 

1997 71.0 1231.7 

1998 69.6 1384.4 

1999 132.8 711.4 

2000 214.5 434.0 

Source: Cogema 2008, Table 5.13 

Table 35: Christensen / Irigaray 

Estimated Radon Release 

Source Release (Ci/yr) 

Production 281 

Restoration 257 

Drilling 0.04 

Resin Transfer 0.42 

Total 538.46 

Source: Cogema 2008, Table 7.3-2 

For the Christensen / Irigaray site, the maximum annual radon release rate was assumed to be 

1,600 Ci, while the average annual release rate is 1,040 Ci. 

2.6.4 Risk Estimates 

The RMEI and population doses and risks calculated by CAP88 for the Christensen / Irigaray 

site are shown in Table 36. 

Table 36: Christensen / Irigaray Risk Assessment Results 

Receptor / Impact 

Radon Release (Ci/yr) 

Unitized Maximum Average 

1 1,600 1,040 

RMEI 

(3500m SE) 

Dose (mrem/yr) 9.1E-04 1.9E+00 1.1E+00 

LCF Risk (yr-1) 4.8E-10 9.9E-07 5.7E-07 

Population Dose (person-rem/yr) 1.8E-03 3.8E+00 2.2E+00 

LCF Risk (yr-1) 1.2E-08 2.4E-05 1.4E-05 
WA 1-04, Task 5 43 SC&A – November 10, 2011

2.7 Alta Mesa 1,2,37

The Alta Mesa Project uranium deposits, located in southern Brooks County, Texas, were 

discovered in the mid-1970s, and some exploration drilling and monitor well installation were 

started in the 80s and early 90s. However, due to low uranium prices, the project was not 

developed. When Uranium Resources Inc. began licensing the Alta Mesa Project, the Texas 

Natural Resource Conservation Commission (TNRCC) was the regulatory agency. In 1998, 

Uranium Resources Inc. received permit number UR03060 from the TNRCC. Due to the 

depressed uranium market, URI abandoned the project in 1999, which was then continued by 

Mesteña Uranium LLC. Licensing and permitting effort proceeded to 2002. In 2002, the Texas 

Department of Health, Bureau of Radiation Control issued material license number L05360 for 

the operation of the Alta Mesa in situ uranium mine to Mesteña Uranium. Development 

activities began in late 2004, and construction of the production facilities began in January 2005. 

Despite challenges due to three hurricanes, and short supplies of materials, equipment, and 

trained personnel, the Alta Mesa Project started, as planned, in October 2005. The Alta Mesa 

Project produced 480,000 lbs of U3O8 in 2009, and plans to produce about 650,000 lbs of U3O8

in 2010. 

In 2007, the responsibility for source material recovery (i.e., uranium surface mining activities) 

licensing was transferred to the Texas Department of State Health Services (TDSHS) to the 

Texas Commission on Environmental Quality (TCEQ). The Texas Railroad Commission 

(TRRC) retains responsibility for permitting for exploration wells for uranium mining. 

The uranium mineralization occurs at depths from 150 to 500+ feet deep in different sandstone 

units of the Pliocene Goliad Formation, with an average thickness of 14.3 feet. The majority of 

the mineable reserves as of 1994 had been found in a sandstone unit designated the Middle C 

Sand Unit, with ore quality mineralization ranging from 420 to 480 feet deep. The uranium 

occurs along multiple, relatively continuous oxidation-reduction fronts that range in width from 

50 to 200+ feet wide. The Alta Mesa uranium deposit has an average ore grade of 0.096% U3O8. 

The Alta Mesa Project, shown in Figure 12, uses conventional ion exchange precipitation 

processes and a low-temperature, zero-emission rotary vacuum dryer. The facility and well 

fields are designed for flexibility of operations. 

 

7

 The description of the Alta Mesa site was abstracted from various sources, including Tanner and Goranson 

2007, Melbye 2008, and McNeill 2010, while the aerial view of the Alta Mesa site was obtained from Google 

Maps. 
WA 1-04, Task 5 44 SC&A – November 10, 2011

Figure 12: Alta Mesa – Aerial View 

2.7.1 Population and Food Production 

The 80-kilometer population distribution in each of the 16 principal compass directions, which 

was calculated for the Alta Mesa site by SECPOP and used in CAP88 for population dose 

calculations, is shown in Table 37. To adjust the 2000 population data to 2010, the CAP88 Alta 

Mesa population dose was multiplied by 0.92, see Section 1.2 and Table 3. 
WA 1-04, Task 5 45 SC&A – November 10, 2011

Table 37: Alta Mesa 1,2,3 Population Data 

Dir Distance (km) 

0 to 1 1 to 2 2 to 3 3 to 4 4 to 5 5 to 10 10 to 20

N 0 0 0 0 0 2 0 

NNW 0 0 6 0 0 0 0 

NW 0 0 0 0 0 0 0 

WNW 0 0 0 0 0 0 0 

W 0 0 6 0 0 0 0 

WSW 0 0 0 0 0 0 9 

SW 0 0 0 0 0 0 0 

SSW 0 0 0 0 0 0 51 

S 0 0 0 0 0 10 38 

SSE 0 0 0 0 0 0 0 

SE 0 0 0 0 0 41 0 

ESE 0 0 0 0 0 14 0 

E 0 0 69 0 0 79 198 

ENE 0 0 0 0 0 6 112 

NE 0 0 0 0 0 0 0 

NNE 0 0 0 0 0 0 0 

Dir Distance (km) 

20 to 30 30 to 40 40 to 50 50 to 60 60 to 70 70 to 80 

N 11 17 197 577 184 2454 

NNW 6 0 73 106 309 41 

NW 7 13 0 4748 339 482 

WNW 0 14 5 25 28 30 

W 22 3 0 26 16 84 

WSW 0 114 21 44 78 19 

SW 239 149 155 47 502 20610 

SSW 462 13 38 33 2458 17761 

S 81 56 103 2305 65220 201974 

SSE 3 56 1058 6732 41029 66913 

SE 25 60 34 69 7733 9454 

ESE 6 0 0 65 26 404 

E 18 0 8 48 0 0 

ENE 18 4 3 8 8 24 

NE 3 42 201 36 1542 5971 

NNE 5 4518 2862 3377 48 3089 

The agricultural productivity factors for Texas were taken from Appendix C of the CAP88 

User’s Manual, as shown below, and used in the Alta Mesa site population dose calculation. 

Beef Cattle Density (cattle/km2): 19 

Milk Cattle Density (cow/km2): 0.53 

Land Cultivated for Vegetable Crops: 0.577% 

According to Mestena 2000, Table 3.2, the nearest resident to the Alta Mesa site is located about 

2.5 km in the WSW direction. Table 37 also shows the nearest resident as being 2 to 3 km from 
WA 1-04, Task 5 46 SC&A – November 10, 2011

the site, but in the NNW, West, and East directions. Through analysis using CAP88, the RMEI 

was identified to be located 2 to 3 km in the NNW direction. 

2.7.2 Meteorology 

The U.S. Naval Air Base in Kingsville, which is much closer to the site than any of the NWS 

stations (45miles northeast), collects meteorological data, including wind speed, wind direction, 

and stability class. Meteorological data from the Kingsville Naval Air Base were used by 

Mestena Uranium to formulate a joint frequency distribution for the dose calculations performed 

as part of the Alta Mesa license application. For this risk assessment, the meteorological data 

from the Alta Mesa license application were reformatted so that they could be processed by the 

CAP88 auxiliary program, WINDGET (Trinity 2007), which generated a meteorological data 

file in the format required by CAP88 (i.e., a .WND file). Table 38 shows the directionaldependent average wind speed for each stability class that was used in this risk assessment for 

the Alta Mesa site, while Table 39 gives the stability class frequency. 

Table 38: Alta Mesa / Kingsville Dome Arithmetic Average Wind Speeds 

(Wind Towards) 

Dir Pasquill Stability Class (m/s) 

A B C D E F G 

N 2.012 3.266 5.985 7.300 4.983 2.017 0.000 

NNW 1.743 3.518 5.521 7.872 5.115 2.003 0.000 

NW 2.000 3.566 6.077 7.482 5.107 1.975 0.000 

WNW 1.823 3.648 5.834 7.200 4.799 1.659 0.000 

W 1.680 2.995 5.338 5.648 4.244 1.533 0.000 

WSW 1.488 2.699 4.844 5.468 3.866 1.341 0.000 

SW 1.439 2.713 4.849 5.512 4.025 1.601 0.000 

SSW 1.300 2.720 4.888 6.149 4.340 1.624 0.000 

S 2.208 2.618 4.761 6.445 4.705 1.633 0.000 

SSE 1.826 2.395 5.180 6.390 4.763 1.659 0.000 

SE 2.556 2.373 5.205 6.202 4.782 1.642 0.000 

ESE 2.556 2.924 4.545 6.220 4.388 1.695 0.000 

E 1.027 1.982 4.278 4.734 4.203 1.542 0.000 

ENE 1.029 1.762 3.991 3.652 6.112 1.462 0.000 

NE 1.826 3.573 4.278 5.487 3.962 1.344 0.000 

NNE 1.814 2.600 5.346 6.672 4.431 1.945 0.000 
WA 1-04, Task 5 47 SC&A – November 10, 2011

Table 39: Alta Mesa / Kingsville Dome Frequencies of Stability Classes 

(Wind Towards) 

Dir Pasquill Stability Class (frequency) 

A B C D E F G

N 0.0162 0.0700 0.1047 0.4226 0.1090 0.2775 0.0000 

NNW 0.0146 0.0529 0.0762 0.4792 0.1186 0.2585 0.0000 

NW 0.0091 0.0354 0.0771 0.4761 0.1313 0.2710 0.0000

WNW 0.0060 0.0474 0.1093 0.4900 0.0947 0.2526 0.0000 

W 0.0201 0.0745 0.1079 0.3680 0.0769 0.3526 0.0000 

WSW 0.0176 0.0876 0.1120 0.4117 0.0694 0.3017 0.0000 

SW 0.0092 0.0676 0.1025 0.5021 0.0816 0.2370 0.0000

SSW 0.0085 0.0756 0.1033 0.5325 0.0657 0.2144 0.0000 

S 0.0084 0.0471 0.0879 0.5084 0.0913 0.2568 0.0000 

SSE 0.0040 0.0493 0.0830 0.4447 0.0741 0.3448 0.0000 

SE 0.0045 0.0523 0.0751 0.3448 0.0726 0.4507 0.0000

ESE 0.0081 0.0724 0.1158 0.2966 0.0553 0.4517 0.0000 

E 0.0242 0.1773 0.0492 0.1892 0.0375 0.5226 0.0000 

ENE 0.0244 0.1323 0.0997 0.1670 0.0082 0.5683 0.0000 

NE 0.0189 0.1679 0.1463 0.3258 0.0619 0.2792 0.0000

NNE 0.0389 0.1298 0.1531 0.3888 0.0518 0.2377 0.0000 

TOTAL 0.0121 0.0617 0.0949 0.4520 0.0945 0.2848 0.0000 

2.7.3 Radon Release 

The only information identified regarding radon release from the Alta Mesa Project was 

contained within the June 2000 radiological assessment performed for the project (Mestena 

2000). The following is the radiological assessment’s description of the Alta Mesa radon 

release. 

Radon gas will be emitted at the central facility when the circulating fluids are brought 

into equilibrium with the ambient atmosphere. The emission points will be all open 

tankage, resin columns and processing equipment. 

Two centralized discharge areas of radon gas were modeled, one centered on the 

production area of the process pad (Production Pad) and one centered on the restoration 

area of the process pad (Restoration Pad). An additional point source for radon was 

modeled based on the center of the pond receiving purge water (Purge Pond). 

Additional radon gas will be emitted at the wellfields because of well field venting and 

other small releases. These sites were modeled as small area sources centered on points 

within each wellfield which represented a one year production element. [Mestena 2000, 

Appendix 1] 

The Alta Mesa annual radon release, as presented in the radiological assessment (Mestena 2000), 

is shown in Table 40. 
WA 1-04, Task 5 48 SC&A – November 10, 2011

Table 40: Alta Mesa Annual 

Radon Source Term 

Source Release (Ci/yr) 

Well field 1a 5.2 

Well field 1b 6.05 

Well field 2a 4.81 

Well field 2b 5.09 

Well field 3a 1.67 

Well field 3b 2.5 

Well field 4 2.09 

Process Pad 617.5 

Restoration Pad 88.35 

Purge Pond 6.5 

Total 739.8 

Source: Mestena 2000, Attachment 1 

The radon releases given in Table 40 are design basis values; and, as such, are based on the Alta 

Mesa uranium production capacity of 1,500,000 lbs per year. As stated above, the amount of 

uranium produced at Alta Mesa has been somewhat less than its production capacity. Table 41 

gives the Alta Mesa annual radon release as a function of the amount of uranium produced. 

Table 41: Alta Mesa Radon Release by 

Uranium Production 

Year 

Uranium 

Production 

(lbs/yr) 

Radon Release 

(Ci/yr) 

2007 956,000 471 

2009 480,000 237 

2010 650,000 321 

Capacity 1,500,000 740 

2.7.4 Risk Estimates 

The RMEI and population doses and risks calculated by CAP88 for the Alta Mesa site are shown 

in Table 42. 

Table 42: Alta Mesa Risk Assessment Results 

Receptor / Impact 

Radon Release (Ci/yr) 

Unitized Maximum Average 

1 740 472 

RMEI 

(2500m NNW) 

Dose (mrem/yr) 5.6E-03 1.2E+01 6.7E+00 

LCF Risk (yr-1) 3.0E-09 6.1E-06 3.6E-06 

Population Dose (person-rem/yr) 1.0E-02 2.2E+01 1.3E+01 

LCF Risk (yr-1) 6.3E-08 1.3E-04 7.6E-05 
WA 1-04, Task 5 49 SC&A – November 10, 2011

2.8 Kingsville Dome 1,38

Uranium Resources, Inc.’s (URI’s) Kingsville Dome property consists of mineral leases from 

private landowners on about 2,354 acres located in central Kleberg County, Texas. An aerial 

view of the Kingsville Dome site is shown in Figure 13. For the Kingsville Dome site, URI 

holds the TNRCC’s Underground Injection Control Permit: UR02827; the site is also covered by 

the Texas Department of Health’s radioactive materials license: L06353. At Kingsville Dome, 

multiple satellites feed a central processing plant at a rate of 400,000 pounds of U3O8 (154 

tonnes U) per year (targeting between 1 and 2 million pounds of U3O8 (385-770 tonnes U) 

annually). Initial production commenced in May 1988 and continued until July 1999, when 

depressed uranium prices led to the suspension of production. URI resumed production at 

Kingsville Dome in April 2006 and produced 94,100 pounds of uranium in 2006, 338,100 

pounds in 2007, 254,000 pounds in 2008, and 56,000 pounds in 2009. In the second quarter of 

2009, due to depressed pricing, production at Kingsville Dome was shut-down to conserve the 

in-place reserve base until higher prices could be realized. 

Figure 13: Kingsville Dome – Aerial View 

 

8

 The description of the Kingsville Dome site was abstracted from various sources, including Melbye 2008, URI 

2010a, and URI 2010b while the aerial view of the Kingsville Dome site was obtained from Google Maps. 
WA 1-04, Task 5 50 SC&A – November 10, 2011

2.8.1 Population and Food Production 

The 80-kilometer population distribution in each of the 16 principal compass directions, which 

was calculated for the Kingsville Dome site by SECPOP and used in CAP88 for population dose 

calculations, is shown in Table 43. To adjust the 2000 population data to 2010, the CAP88 

Kingsville Dome population dose was multiplied by 0.97, see Section 1.2 and Table 3. 

Table 43: Kingsville Dome 1,3 Population Data 

Dir Distance (km) 

0 to 1 1 to 2 2 to 3 3 to 4 4 to 5 5 to 10 10 to 20

N 0 0 0 0 0 54 3796 

NNW 0 0 0 0 0 0 21 

NW 0 0 0 0 0 0 0 

WNW 0 0 0 0 0 0 0 

W 0 0 0 0 0 0 0 

WSW 0 0 82 0 0 0 0 

SW 0 0 3 0 0 87 393 

SSW 0 0 0 0 0 37 189 

S 0 0 0 0 0 41 248 

SSE 0 0 0 0 0 240 512 

SE 0 0 0 0 138 0 0 

ESE 0 0 66 0 0 461 288 

E 0 0 0 39 27 677 409 

ENE 0 0 0 91 30 369 265 

NE 0 0 0 0 0 537 18252 

NNE 0 0 7 0 0 74 7920 

Dir Distance (km) 

20 to 30 30 to 40 40 to 50 50 to 60 60 to 70 70 to 80 

N 1134 1242 2185 3921 2450 8983 

NNW 330 1026 19092 24698 4509 14441 

NW 276 296 60486 159467 14418 15036 

WNW 0 77 2009 29018 305 181 

W 0 0 6 0 0 0 

WSW 0 0 0 0 0 0 

SW 0 0 0 0 0 0 

SSW 30 0 0 0 0 0 

S 148 5 0 51 5 30 

SSE 80 6 4 0 172 8 

SE 25 613 68 8 160 235 

ESE 0 1724 6133 99 26 22 

E 0 2495 503 189 301 276 

ENE 0 26 469 259 2036 125 

NE 0 649 23849 6994 1116 52 

NNE 126 302 1209 1430 3988 750 
WA 1-04, Task 5 51 SC&A – November 10, 2011

The agricultural productivity factors for Texas were taken from Appendix C of the CAP88 

User’s Manual, as shown below, and used in the Kingsville Dome site population dose 

calculation. 

Beef Cattle Density (cattle/km2): 19 

Milk Cattle Density (cow/km2): 0.53 

Land Cultivated for Vegetable Crops: 0.577% 

According to TBRC 1988, Table S6.9-2, the nearest downwind resident to the Kingsville Dome 

site is located about 1.35 km in the West direction, and the nearest resident is located 0.44 km in 

the East direction. Table 43 also shows the nearest residents to the Kingsville Dome site as 

being about 2 to 3 km from the site, but in the WSW, ESE, and NNE directions. Through 

analysis using CAP88, the RMEI was found to be located 2 to 3 km in the NNW direction. 

2.8.2 Meteorology 

Because of the close proximity of the Kingsville Dome site to the Alta Mesa site (less than 50 

miles) and because Kingsville Naval Air Base is the closest meteorological station to both, the 

meteorological data used for the Kingsville Dome site are the same as that used for the Alta 

Mesa site. Table 38 shows the directional-dependent average wind speed for each stability class 

that was used in this risk assessment for the Kingsville Dome site, while Table 39 gives the 

stability class frequency. 

2.8.3 Radon Release 

The only information identified regarding radon release from the Kingsville Dome site was in the 

Environmental Assessment (EA) prepared by the Texas Department of Health (TDH 1988). In 

the Kingsville Dome EA, the TDH estimated the annual radon release to be 6,958 Ci. If this 

radon release rate is assumed to correspond to the Kingsville Dome uranium production capacity, 

then the reported uranium production rates may be used to estimate the radon released for other 

years. This has been done, with the results shown in Table 44. 

Table 44: Kingsville Dome Radon Release by 

Uranium Production 

Year 

Uranium 

Production 

(lbs/yr) 

Radon Release 

(Ci/yr) 

2006 94,100 655 

2007 338,100 2,352 

2008 254,000 1,767 

2009 56,000 390 

Capacity 1,000,000 6,958 

The maximum annual radon release from the Kingsville Dome site is assumed to be 6,958 Ci, 

while the average annual release is 1,291 Ci. 
WA 1-04, Task 5 52 SC&A – November 10, 2011

2.8.4 Risk Estimates 

The RMEI and population doses and risks calculated by CAP88 for the Kingsville Dome site are 

shown in Table 45. 

Table 45: Kingsville Dome Risk Assessment Results 

Receptor / Impact 

Radon Release (Ci/yr) 

Unitized Maximum Average 

1 6958 1291 

RMEI 

(2500 NNW) 

Dose (mrem/yr) 5.5E-03 1.1E+01 6.6E+00 

LCF Risk (yr-1) 2.9E-09 6.1E-06 3.5E-06 

Population Dose (person-rem/yr) 2.8E-02 5.8E+01 3.4E+01 

LCF Risk (yr-1) 1.8E-07 3.8E-04 2.2E-04 

2.9 Eastern Generic Site – Virginia 

Due to its many uranium deposits, as shown in Figure 14, the state of Virginia was selected for 

the location of the Eastern Generic site. In the early 1980s, uranium mining leases were obtained 

for 40,000 uranium-rich acres in Pittsylvania County and 16,000 acres in Fauquier, Madison, 

Culpeper, and Orange counties. Additionally, uranium deposits were discovered in Nelson 

County (UFV 2010). Because of its high population density and its past experience as a uranium 

mine lease site, Culpeper County was selected as the Eastern Generic site location within 

Virginia. 

Figure 14: Potential Uranium in Virginia 
WA 1-04, Task 5 53 SC&A – November 10, 2011

The actual Eastern Generic site location within Culpeper County was selected so that there 

would be no population located within 1 km of the site. Figure 15 shows the approximate 

location of the Eastern Generic site, located in the northern portion of Virginia’s Culpeper 

County. 

Figure 15: Approximate Location of the Eastern Generic Site 

As shown in Figure 15, the Eastern Generic site is located north of the city of Culpeper and 

southwest of the city of Warrenton in an uninhabited area. Also, the areas in red on Figure 15 

denote areas that have had uranium mine leases in the past. 

2.9.1 Population and Food Production 

The 80-kilometer population distribution in each of the 16 principal compass directions, which 

was calculated for the Eastern Generic site by SECPOP and used in CAP88 for population dose 

calculations, is shown in Table 46. To adjust the 2000 population data to 2010, the CAP88 

Eastern Generic population dose was multiplied by 1.40, see Section 1.2 and Table 3. 
WA 1-04, Task 5 54 SC&A – November 10, 2011

Table 46: Eastern Generic Site (Virginia) Population Data 

Dir Distance (km) 

0 to 1 1 to 2 2 to 3 3 to 4 4 to 5 5 to 10 10 to 20

N 0 0 0 5 160 442 588 

NNW 0 11 154 0 2 816 1072 

NW 0 0 0 125 76 741 2358 

WNW 0 0 0 0 38 457 2105 

W 0 0 0 38 0 367 2077 

WSW 0 0 8 28 2 159 1608 

SW 0 0 10 0 0 730 953 

SSW 0 0 0 332 55 623 4037 

S 0 0 0 0 0 841 10192 

SSE 0 0 0 0 0 542 2474 

SE 0 0 213 0 0 545 1393 

ESE 0 0 143 0 130 187 598 

E 0 0 197 38 35 135 349 

ENE 0 0 147 1 31 176 711 

NE 0 0 0 0 30 175 938 

NNE 0 0 9 16 63 91 523 

Dir Distance (km) 

20 to 30 30 to 40 40 to 50 50 to 60 60 to 70 70 to 80 

N 931 3140 2718 5208 36454 23280 

NNW 1714 3578 3065 5089 16570 12798 

NW 8464 4721 9451 11662 114035 115934 

WNW 7907 8202 55966 135173 247760 367208 

W 5161 2433 4498 69279 132991 40611 

WSW 2868 4336 17263 58995 13734 5773 

SW 1204 6574 9500 66863 23680 4796 

SSW 651 3098 2808 4588 5366 7093 

S 1947 3289 2997 2925 6611 4356 

SSE 2407 4923 3356 6393 6092 41432 

SE 2420 2990 5214 11763 17293 45571 

ESE 1026 176 1095 10894 6452 50227 

E 287 5893 7017 4870 11750 10706 

ENE 446 3733 1566 8154 4049 1475 

NE 542 2114 1487 13550 1098 1816 

NNE 1160 17008 8288 19156 18827 6533 

The agricultural productivity factors for Virginia were taken from Appendix C of the CAP88 

User’s Manual, as shown below, and used in the Eastern Generic site population dose 

calculation. 

Beef Cattle Density (cattle/km2): 13.1 

Milk Cattle Density (cow/km2

): 1.84 

Land Cultivated for Vegetable Crops: 0.87% 
WA 1-04, Task 5 55 SC&A – November 10, 2011

The Eastern Generic site was selected so that there would be no population within 1 km of the 

site. Thus, the RMEI at the Eastern Generic site is located 1 to 2 km from the site in the NNW 

direction, as shown in Table 46. 

2.9.2 Meteorology 

The CAP88 computer program is provided with a weather library of meteorological data from 

over 350 NWS stations. For the Eastern Generic site, the CAP88-provided weather data for 

Gordonsville, VA (CAP88 File: GVE0824.WND) were used. The period of record for this data 

includes the years 1956 through 1960. Table 47 shows the directional-dependent average wind 

speed for each stability class, while Table 48 gives the stability class frequency, used in the 

Eastern Generic analysis. 

Table 47: Eastern Generic Site (Virginia) Arithmetic Average Wind Speeds 

(Wind Towards) 

Dir Pasquill Stability Class (m/s) 

A B C D E F G 

N 1.184 1.737 2.755 2.990 2.955 1.102 0.000 

NNW 1.132 1.852 2.758 2.860 2.878 1.108 0.000 

NW 1.170 1.542 2.067 2.420 2.704 1.070 0.000 

WNW 1.172 1.433 2.263 2.400 3.093 1.049 0.000 

W 1.141 1.473 2.120 2.163 2.678 1.028 0.000 

WSW 1.177 1.876 2.622 2.463 2.935 1.086 0.000 

SW 1.076 1.740 2.839 2.819 2.949 1.089 0.000 

SSW 1.177 1.975 3.334 3.646 3.384 1.138 0.000 

S 1.174 1.912 2.781 3.343 3.210 1.098 0.000 

SSE 1.278 2.144 3.260 3.730 3.479 1.116 0.000 

SE 1.204 1.990 3.147 4.179 3.569 1.133 0.000 

ESE 1.238 2.327 3.518 5.455 4.076 1.164 0.000 

E 1.197 1.917 3.220 4.912 3.887 1.140 0.000 

ENE 1.201 2.030 3.276 4.479 3.784 1.131 0.000 

NE 1.196 1.871 3.054 3.468 3.330 1.099 0.000 

NNE 1.197 2.102 3.273 3.985 3.333 1.114 0.000 
WA 1-04, Task 5 56 SC&A – November 10, 2011

Table 48: Eastern Generic Site (Virginia) Frequencies of Stability Classes 

(Wind Towards) 

Dir Pasquill Stability Class (frequency) 

A B C D E F G

N 0.0224 0.0863 0.1225 0.3226 0.0791 0.3672 0.0000 

NNW 0.0238 0.0788 0.1438 0.3242 0.0874 0.3421 0.0000 

NW 0.0424 0.1049 0.1395 0.3309 0.0502 0.3321 0.0000

WNW 0.1047 0.1644 0.1440 0.3753 0.0276 0.1840 0.0000 

W 0.0709 0.1887 0.1336 0.3718 0.0215 0.2134 0.0000 

WSW 0.0528 0.1127 0.1576 0.4373 0.0502 0.1893 0.0000 

SW 0.0206 0.0857 0.1223 0.4187 0.0629 0.2898 0.0000

SSW 0.0132 0.0509 0.0951 0.5464 0.0594 0.2350 0.0000 

S 0.0108 0.0397 0.0722 0.4681 0.0522 0.3570 0.0000 

SSE 0.0091 0.0519 0.0728 0.2914 0.0626 0.5122 0.0000 

SE 0.0179 0.0404 0.0862 0.2618 0.0774 0.5163 0.0000

ESE 0.0159 0.0619 0.1244 0.4009 0.1222 0.2748 0.0000 

E 0.0292 0.0641 0.1222 0.3285 0.1067 0.3492 0.0000 

ENE 0.0290 0.1081 0.1642 0.3326 0.0826 0.2835 0.0000 

NE 0.0288 0.0982 0.1551 0.3305 0.0670 0.3203 0.0000

NNE 0.0198 0.0820 0.1513 0.4027 0.0777 0.2664 0.0000 

TOTAL 0.0231 0.0767 0.1219 0.3784 0.0716 0.3282 0.0000 

2.9.3 Radon Release 

It is assumed that a conventional uranium mine and mill would be located at the Eastern Generic 

site, and that the annual radon release from the Eastern Generic site would be similar to the radon 

released from the conventional mill located at White Mesa (see Section 2.2.3). Thus, the Eastern 

Generic site annual radon release was estimated to range from 1,025 to 1,750 Ci. 

2.9.4 Risk Estimates 

The RMEI and population doses and risks calculated by CAP88 for the Eastern Generic site are 

shown in Table 49. 

Table 49: Eastern Generic Site Risk Assessment Results 

Receptor / Impact 

Radon Release (Ci/yr) 

Unitized Maximum Average 

1 1750 1388 

RMEI 

(500m SSE) 

Dose (mrem/yr) 1.4E-02 2.8E+01 1.6E+01 

LCF Risk (yr-1) 7.6E-09 1.6E-05 9.2E-06 

Population Dose (person-rem/yr) 9.7E-02 2.0E+02 1.2E+02 

LCF Risk (yr-1) 6.6E-07 1.4E-03 7.9E-04 
WA 1-04, Task 5 57 SC&A – November 10, 2011

2.10 Western Generic Site – New Mexico9

The Grants Uranium Region in New Mexico is a world premier uranium mining district, having 

produced over 350 million pounds of uranium. During the 1970s, a conventional uranium mine 

and mill were developed by a joint venture between Long Island Lighting Company, a New York 

utility, and Bokum Resources Corporation. In addition to deposit development drilling, a shaft 

was sunk to a depth of 1,842 feet, a 2,200 ton-per-day uranium processing mill was constructed 

on site, and a tailings disposal site was excavated, all fully permitted. Due to the collapse in the 

uranium market in the early 1980s, development was halted, the deposit remains un-mined, and 

the mill was dismantled in 2001. According to Nuclear Regulatory Commission records, the 

source material license was terminated in 1988 following multiple inspections, which confirmed 

that no ore was ever produced or processed at the site. Although the mill has been removed, 

much of the infrastructure remains in place, including electric power, 1,800+ acre-feet of 

industrial-use water rights, the 1,842 shaft, and the previously permitted and partially completed 

tailings disposal site. The site is currently being considered for redevelopment as a conventional 

uranium mine and mill. 

The Bokum mill was designed to accommodate 2,200 tons of ore feed per day. Metallurgical 

studies and yearly production were based on an average mill feed of 0.12% U3O8. Grinding was 

to be accomplished by a semi-autogenous mill and a rod mill. A two-stage sulfuric acid leach 

circuit was to be utilized. Liquid-solid separation was to use six stages of counter-current 

decantation, with clarification of overflows from inter-stage thickening. Solvent extraction and 

stripping for solubilization and removal of uranium was to be employed, and ammonia was to be 

used to precipitate the U3O8 as yellowcake. 

The site of the former Bokum mine and mill was selected as the Western Generic site. It was 

assumed that a conventional mine and mill similar to the mine and mill previously proposed and 

partially constructed, but updated to reflect current 2010 technology, would be constructed. 

2.10.1 Population and Food Production 

The 80-kilometer population distribution in each of the 16 principal compass directions, which 

was calculated for the Western Generic site by SECPOP and used in CAP88 for population dose 

calculations, is shown in Table 50. To adjust the 2000 population data to 2010, the CAP88 

Western Generic population dose was multiplied by 0.94, see Section 1.2 and Table 3. 

 

9

 The description of the Western Generic site was abstracted from various sources, including Alief 2010, NE 

2008a, and NE 2008b. 
WA 1-04, Task 5 58 SC&A – November 10, 2011

Table 50: Western Generic Site (New Mexico) Population Data 

Dir Distance (km) 

0 to 1 1 to 2 2 to 3 3 to 4 4 to 5 5 to 10 10 to 20

N 0 0 0 0 0 0 0 

NNW 0 0 0 0 0 0 0 

NW 0 0 0 0 0 0 0 

WNW 0 0 0 0 0 0 0 

W 0 0 0 0 0 0 0 

WSW 0 0 0 0 0 0 2 

SW 0 0 0 0 0 0 0 

SSW 0 0 0 0 0 0 0 

S 0 0 0 0 0 0 24 

SSE 0 0 0 0 0 2 341 

SE 0 0 0 0 0 8 45 

ESE 0 0 0 0 0 2 298 

E 0 0 0 0 2 12 259 

ENE 0 0 0 0 0 49 163 

NE 0 0 0 7 1 43 365 

NNE 0 0 0 4 4 14 36 

Dir Distance (km) 

20 to 30 30 to 40 40 to 50 50 to 60 60 to 70 70 to 80 

N 0 4 0 1 65 206 

NNW 38 294 108 468 177 693 

NW 77 0 18 228 555 588 

WNW 4 0 95 254 1311 308 

W 0 0 0 0 7 7 

WSW 0 0 0 5 3 74 

SW 169 0 0 724 1951 1215 

SSW 28 618 23 2285 1226 44 

S 116 2674 10176 449 17 1 

SSE 274 617 18 29 125 126 

SE 1126 643 1 0 489 815 

ESE 534 2110 269 77 15 756 

E 700 511 982 2009 2928 19973 

ENE 177 162 550 836 314 1318 

NE 1302 1683 425 230 22 35 

NNE 96 0 32 19 377 254 

The agricultural productivity factors for New Mexico were taken from Appendix C of the 

CAP88 User’s Manual, as shown below, and used in the Western Generic site population dose 

calculation. 

Beef Cattle Density (cattle/km2): 4.13 

Milk Cattle Density (cow/km2

): 0.114 

Land Cultivated for Vegetable Crops: 0.138% 
WA 1-04, Task 5 59 SC&A – November 10, 2011

As indicated in Table 50, for the Western Generic site, the nearest individual is located between 

3 and 4 km in the NE and NNE directions, which is consistent with NEI 2008, which states that 

the nearest downwind resident is at about 2.5 miles. Through analysis with CAP88, the RMEI 

was identified to be located 2 to 3 km in the NNW direction. 

2.10.2 Meteorology 

The CAP88 computer program is provided with a weather library of meteorological data from 

over 350 NWS stations. For the Western Generic site, the CAP88-provided weather data for 

Grants, NM (CAP88 File: GNT1246.WND) were used. The period of record for this data is 

limited to the year 1954. Table 51 shows the directional-dependent average wind speed for each 

stability class, while Table 52 gives the stability class frequency, used in the Western Generic 

analysis. 

Table 51: Western Generic Site (New Mexico) Arithmetic Average Wind Speeds 

(Wind Towards) 

Dir Pasquill Stability Class (m/s) 

A B C D E F G 

N 1.324 2.175 3.366 4.871 3.773 1.202 0.000 

NNW 0.772 1.518 3.561 5.734 3.664 1.368 0.000 

NW 1.271 1.951 3.733 5.719 3.751 1.278 0.000 

WNW 1.183 2.088 4.141 5.835 3.697 1.337 0.000 

W 0.772 1.792 2.944 3.982 3.155 0.888 0.000 

WSW 0.772 4.373 4.373 4.008 4.373 1.372 0.000 

SW 0.772 1.410 1.610 2.594 3.299 1.149 0.000 

SSW 0.772 2.347 3.163 4.907 3.933 1.176 0.000 

S 1.088 1.772 3.251 5.126 4.035 1.286 0.000 

SSE 1.104 1.537 3.505 5.737 4.217 1.497 0.000 

SE 1.099 1.526 3.142 5.306 4.213 1.393 0.000 

ESE 1.246 1.954 3.378 6.231 4.191 1.515 0.000 

E 1.324 1.732 3.819 6.684 4.040 1.419 0.000 

ENE 1.183 2.174 5.214 7.451 4.189 1.496 0.000 

NE 0.993 1.938 3.978 6.664 3.800 1.294 0.000 

NNE 1.141 2.658 4.743 6.129 3.630 1.255 0.000 
WA 1-04, Task 5 60 SC&A – November 10, 2011

Table 52: Western Generic Site (New Mexico) Frequencies of Stability Classes 

(Wind Towards) 

Dir Pasquill Stability Class (frequency) 

A B C D E F G

N 0.0277 0.0653 0.1118 0.2731 0.1517 0.3705 0.0000 

NNW 0.0169 0.0555 0.0852 0.3901 0.1569 0.2954 0.0000 

NW 0.0367 0.1338 0.1667 0.3783 0.0887 0.1959 0.0000

WNW 0.0179 0.1259 0.1877 0.4097 0.0661 0.1926 0.0000 

W 0.0650 0.2801 0.1804 0.2975 0.0295 0.1474 0.0000 

WSW 0.1381 0.0410 0.2127 0.1866 0.0410 0.3806 0.0000 

SW 0.0875 0.2602 0.0852 0.1832 0.0665 0.3174 0.0000

SSW 0.0754 0.1447 0.1156 0.3106 0.0452 0.3085 0.0000 

S 0.0464 0.1383 0.1320 0.2285 0.1295 0.3254 0.0000 

SSE 0.0290 0.1021 0.1406 0.2746 0.1637 0.2899 0.0000 

SE 0.0103 0.0722 0.1104 0.1905 0.2485 0.3682 0.0000

ESE 0.0188 0.0387 0.0695 0.2171 0.3169 0.3391 0.0000 

E 0.0111 0.0827 0.0998 0.3827 0.1368 0.2869 0.0000 

ENE 0.0238 0.0680 0.1257 0.4770 0.1423 0.1633 0.0000 

NE 0.0486 0.1099 0.1260 0.4649 0.0564 0.1943 0.0000

NNE 0.0437 0.1148 0.1547 0.4117 0.0758 0.1992 0.0000 

TOTAL 0.0258 0.0932 0.1243 0.3070 0.1679 0.2817 0.0000 

2.10.3 Radon Release 

It was assumed that a conventional uranium mill would be located at the Western Generic site, as 

that was the type of mill that was licensed to operate there in the 1990s. As such, it was decided 

to use the annual radon release from the White Mesa site for the Western Generic site (see 

Section 2.2.3). Thus, the Western Generic site annual radon release was estimated to range from 

1,025 to 1,750 Ci. 

2.10.4 Risk Estimates 

The RMEI and population doses and risks calculated by CAP88 for the Western Generic site are 

shown in Table 53. 

Table 53: Western Generic Site Risk Assessment Results 

Receptor / Impact 

Radon Release (Ci/yr) 

Unitized Maximum Average 

1 1,750 1,388 

RMEI 

(3500m NNW) 

Dose (mrem/yr) 2.9E-03 6.0E+00 3.5E+00 

LCF Risk (yr-1) 3.7E-09 7.7E-06 4.4E-06 

Population Dose (person-rem/yr) 2.5E-03 5.1E+00 3.0E+00 

LCF Risk (yr-1) 1.3E-07 2.7E-04 1.6E-04 

 
WA 1-04, Task 5 61 SC&A – November 10, 2011

3.0 SUMMARY OF RESULTS 

Table 54 shows the cumulative population within 80 kilometers of each site. Table 54 reveals a 

difference between the least populated site, Sweetwater, and the most populated site, the Eastern 

Generic site, of more than a factor of 200. If all other factors were equal (e.g., meteorology, 

radon release), this population difference would be directly reflected in the CAP88-calculated 

population doses. It is also interesting to note that while the Cañon City site has only about a 

third of the 80-km population of the Eastern Generic site, the Cañon City site has the largest 

population living within 10 km. 

Table 54: Cumulative 2000 Population Data 

Uranium Site Distance (km) 

0 to 1 0 to 5 0 to 10 0 to 20 0 to 40 0 to 60 0 to 80 

Sweetwater 0 0 3 6 197 885 10,604 

White Mesa 0 969 3,839 4,228 8,080 12,363 20,675 

Crow Butte 0 51 1,336 1,869 9,324 13,251 32,676 

Christensen / Irigaray 0 1 5 78 362 4,366 36,192 

Western Generic 0 18 148 1,681 15,638 35,949 71,944

Smith Ranch – Highlands 0 0 2 222 5,882 55,739 79,694 

Kingsville Dome 0 483 3,060 35,353 45,963 388,110 457,735 

Alta Mesa 0 81 233 641 6,606 29,610 478,440 

Cañon City 0 7,606 32,016 41,028 52,485 313,574 691,284 

Eastern Generic 0 2,097 9,124 41,100 156,443 727,294 2,129,665

Table 54 also shows that for all of the sites analyzed, there are no people living within one 

kilometer of any site, and for the Sweetwater and Smith Ranch – Highland sites, the closest 

resident (i.e., the RMEI) is located about 7.5 km away. Table 55 compares the current actual 

location of the nearest resident (as determined by SECPOP) to the hypothetical worst case 

location (i.e., the nearest location in the most prevalent wind direction). As expected, if the 

distant RMEI’s were to be relocated nearer the site (e.g., Sweetwater and Smith Ranch – 

Highland), their doses would increase significantly. In addition, changing the direction of the 

RMEI can have a significant effect on the dose. For example, moving the Sweetwater RMEI to 

the worst-case location means changing both his/her distance and direction and results in an 

increase of about a factor of 250, but moving the Smith Ranch – Hignland RMEI to the worstcase location means only changing his/her distance, and the dose increase is much less at only a 

factor of about 80. 
WA 1-04, Task 5 62 SC&A – November 10, 2011

Table 55: Comparison of Current RMEI Location Dose/Risk to WorstCase Location Dose/Risk 

Uranium Site 

Current RMEI Location Worst Case Location 

Distance Increase

(km) Direction Dispersion (sec/m3

) Direction Dispersion 

(sec/m3

) 

Sweetwater 7.5 NW 6.63E-08 ENE 1.65E-05 248.9 

White Mesa 1.5 SSE 1.19E-06 SSW 1.73E-05 14.5 

Cañon City 1.5 N 9.29E-07 S 1.63E-05 17.6 

Smith Ranch - Highlands 7.5 E 1.46E-07 E 1.18E-05 81.2 

Crow Butte 1.5 WSW 3.08E-07 N 1.34E-05 43.4 

Christensen / Irigaray 3.5 SE 1.80E-07 ENE 1.02E-05 57.0 

Alta Mesa 2.5 NNW 1.28E-06 NW 2.38E-05 18.5 

Kingsville Dome 2.5 NNW 1.28E-06 NW 2.38E-05 18.5 

Eastern Generic 1.5 NNE 3.76E-06 NE 3.35E-05 8.9 

Western Generic 3.5 NW 2.11E-07 SE 4.52E-05 70.5 

For each of the 10 uranium sites analyzed in this report, Table 56 presents the CAP88-calculated 

RMEI and population dose and risk, normalized to the radon release. To estimate the annual 

dose or risk for a site, simply multiply the normalized dose or risk from Table 56 by the site’s 

annual radon release. For example, if the radon release at the Sweetwater site was 2,075 Ci/yr, 

then the annual RMEI dose at Sweetwater would be 2,075 Ci/yr × 5.6E-04 mrem/Ci = 

1.16 mrem/yr. 

Table 56: Calculated RMEI and Population Dose and Risk 

Normalized to the Radon Release 

Uranium Site

Dose (Ci-1) LCF Risk (Ci-1) 

Population 

(person-rem)

RMEI 

(mrem) Population RMEI 

Sweetwater 2.3E-04 5.6E-04 1.4E-09 2.9E-10 

White Mesa 2.5E-03 5.8E-03 1.6E-08 3.1E-09 

Cañon City 2.4E-02 5.0E-03 1.5E-07 2.6E-09 

Smith Ranch - Highlands 1.8E-03 7.2E-04 1.1E-08 3.7E-10 

Crow Butte 1.3E-03 1.6E-03 8.4E-09 8.4E-10 

Christensen / Irigaray 1.8E-03 9.1E-04 1.2E-08 4.8E-10 

Alta Mesa 1.0E-02 5.6E-03 6.3E-08 3.0E-09 

Kingsville Dome 2.8E-02 5.5E-03 1.8E-07 2.9E-09 

Eastern Generic 9.7E-02 1.4E-02 6.6E-07 7.6E-09 

Western Generic 2.5E-03 2.9E-03 1.3E-07 3.7E-09 

Presenting the normalized doses and risks allows analysis of the effect that siting has on dose and 

risk without the complications posed by the different mining and/or milling operations. From 

Table 56, it can be seen that the RMEI dose/risk can vary by up to about a factor of 50, 
WA 1-04, Task 5 63 SC&A – November 10, 2011

depending on the site where the radon release occurs, while the population dose/risk can vary by 

up to a factor of 450, depending on the site. This population factor is consistent with the factor 

of 200 difference in the 80 km cumulative population difference identified in Table 54, plus 

another factor to account for meteorological differences between the sites and the actual location 

of the population (e.g., if a large fraction of the population is located in a predominant wind 

direction at one site, that site will have a larger population dose/risk than a similar population 

located in a minor wind direction at another site).

Table 57 presents the RMEI and population doses and risks due to the maximum radon releases 

estimated in Section 2.0, for each uranium site. The maximum radon releases were used to 

calculate the doses in order to be able to compare the results to regulatory criteria. For example, 

10CFR § 20.1301 “Dose Limits for Individual Members of the Public” restricts the total 

effective dose equivalent (TEDE) to individual members of the public from the licensed 

operation to less than 100 mrem per year. 

Table 57: Calculated Maximum Total Annual RMEI, Population Dose and Risk 

Uranium Site 

Maximum 

Radon 

Release (Ci/yr)

Annual Dose LCF Risk(a) (yr-1

) 

Population 

(person-rem)

RMEI 

(mrem) Population RMEI 

Sweetwater 2,075 0.5 1.2 2.9E-06 6.0E-07 

White Mesa 1,750 5.2 12.0 3.4E-05 6.4E-06 

Cañon City 269 49.2 10.3 3.1E-04 5.4E-06 

Smith Ranch - Highlands 36,500 3.7 1.5 2.3E-05 7.7E-07 

Crow Butte 8,885 2.7 3.3 1.7E-05 1.7E-06 

Christensen / Irigaray 1,600 3.8 1.9 2.4E-05 9.9E-07 

Alta Mesa 740 21.6 11.5 1.3E-04 6.1E-06 

Kingsville Dome 6,958 58.0 11.3 3.8E-04 6.1E-06 

Eastern Generic 1,750 200.3 28.2 1.4E-03 1.6E-05 

Western Generic 1,750 5.1 6.0 2.7E-04 7.7E-06 

(a)Latent Cancer Fatalities

Table 58 presents the RMEI and population doses and risks due to the average radon releases 

estimated in Section 2.0 for each uranium site. The risks were based on average radon releases 

in order to make it easier to convert these annual risk values into lifetime risk values, by simply 

multiplying the Table 58 values by the number of years that the facility operates for the 

population risk or by the length of time that the individual lives next to the facility for the RMEI 

risk. 
WA 1-04, Task 5 64 SC&A – November 10, 2011

Table 58: Calculated Average Total Annual RMEI, Population Dose and Risk 

Uranium Site Average Radon 

Release (Ci/yr) 

Annual Dose LCF(a) Risk (yr-1

) 

Population 

(person-mrem)

RMEI 

(rem) Population RMEI 

Sweetwater 1,204 0.3 0.7 1.7E-06 3.5E-07 

White Mesa 1,388 3.0 7.0 2.0E-05 3.7E-06 

Cañon City 146 28.6 6.0 1.8E-04 3.1E-06 

Smith Ranch - Highlands 21,100 2.2 0.9 1.3E-05 4.5E-07 

Crow Butte 4,467 1.6 1.9 1.0E-05 1.0E-06 

Christensen / Irigaray 1,040 2.2 1.1 1.4E-05 5.7E-07 

Alta Mesa 472 12.5 6.7 7.6E-05 3.6E-06 

Kingsville Dome 1,291 33.6 6.6 2.2E-04 3.5E-06 

Eastern Generic 1,388 116.3 16.4 7.9E-04 9.2E-06 

Western Generic 1,388 3.0 3.5 1.6E-04 4.4E-06 

(a)Latent Cancer Fatalities

 
WA 1-04, Task 5 65 SC&A – November 10, 2011

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