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Rules and Regulations Federal Register

10811 

Vol. 74, No. 48 

Friday, March 13, 2009 

NUCLEAR REGULATORY 

COMMISSION 

10 CFR Part 63 

RIN 3150–AH68 

[NRC–2005–0011] 

Implementation of a Dose Standard 

After 10,000 Years 

AGENCY: Nuclear Regulatory 

Commission. 

ACTION: Final rule. 

SUMMARY: The U.S. Nuclear Regulatory 

Commission (NRC) is amending its 

regulations governing the disposal of 

high-level radioactive wastes in a 

proposed geologic repository at Yucca 

Mountain, Nevada. The final rule 

implements the U.S. Environmental 

Protection Agency’s (EPA’s) revised 

standards for doses that could occur 

after 10,000 years, but within the period 

of geologic stability. The final rule also 

specifies a range of values for the deep 

percolation rate to be used to represent 

climate change after 10,000 years, as 

called for by EPA, and specifies that 

calculations of radiation doses for 

workers use the same weighting factors 

that EPA is using for calculating 

individual doses to members of the 

public. 

DATES: Effective Date: This final rule is 

effective on April 13, 2009. 

ADDRESSES: Publicly available 

documents related to this rulemaking 

may be viewed electronically on the 

public computers located at the NRC’s 

Public Document Room (PDR), Room 

O1F21, One White Flint North, 11555 

Rockville Pike, Rockville, Maryland. 

The PDR reproduction contractor will 

copy documents for a fee. Selected 

documents and information on this 

rulemaking can be accessed at the 

Federal rulemaking portal, http:// 

regulations.gov by searching on 

rulemaking docket ID: NRC–2005–0011. 

Publicly available documents created 

or received at the NRC are available 

electronically at the NRC’s Electronic 

Reading Room at http://www.nrc.gov/ 

reading-rm/adams.html. From this site, 

the public can gain entry into the NRC’s 

Agencywide Document Access and 

Management System (ADAMS), which 

provides text and image files of NRC’s 

public documents. If you do not have 

access to ADAMS or if there are 

problems in accessing the documents 

located in ADAMS, contact the NRC 

Public Document Room (PDR) Reference 

staff at (800) 397–4209, (301) 415–4737, 

or by e-mail to pdr.resource@nrc.gov. 

FOR FURTHER INFORMATION CONTACT: 

Timothy McCartin, Office of Nuclear 

Material Safety and Safeguards, U.S. 

Nuclear Regulatory Commission, 

Washington, DC 20555–0001, telephone 

(301) 492–3167, e-mail 

Timothy.McCartin@nrc.gov; Janet Kotra, 

Office of Nuclear Material Safety and 

Safeguards, U.S. Nuclear Regulatory 

Commission, Washington, DC 20555– 

0001, telephone (301) 492–3190, e-mail 

Janet.Kotra@nrc.gov; or Robert 

MacDougall, Office of Federal and State 

Materials and Environmental 

Management Programs, U.S. Nuclear 

Regulatory Commission, Washington, 

DC 20555–0001, telephone (301) 415– 

5175, e-mail 

Robert.MacDougall@nrc.gov. 

SUPPLEMENTARY INFORMATION: 

I. Background 

II. Implementation of the Environmental 

Protection Agency’s Final Standards for 

a Compliance Period Beyond 10,000 

Years and Within the Period of Geologic 

Stability 

III. Public Comments and Responses 

1. NRC Adoption of EPA Standards 

2. Clarifications on NRC’s Implementation 

of Features, Events, and Processes for the 

Performance Assessment for the Period 

After 10,000 Years 

3. Climate Change 

4. Use of Current Dosimetry 

5. Comments Beyond the Scope of This 

Rulemaking 

IV. Summary of Final Revisions 

V. Agreement State Compatibility 

VI. Voluntary Consensus Standards 

VII. Finding of No Significant Environmental 

Impact: Availability 

VIII. Paperwork Reduction Act Statement 

IX. Regulatory Analysis 

X. Regulatory Flexibility Certification 

XI. Backfit Analysis 

XII. Congressional Review Act 

I. Background 

On November 2, 2001 (66 FR 55732), 

NRC published its final rule, 10 CFR 

Part 63, governing disposal of high-level 

radioactive wastes in a potential 

geologic repository at Yucca Mountain, 

Nevada. The U.S. Department of Energy 

(DOE) must comply with these 

regulations for NRC to authorize 

construction and license operation of a 

potential repository at Yucca Mountain. 

As mandated by the Energy Policy Act 

of 1992 (EnPA), Public Law 102–486, 

NRC’s final rule was consistent with the 

radiation protection standards issued by 

EPA at 40 CFR Part 197 (66 FR 32074; 

June 13, 2001). EPA developed these 

standards pursuant to Congress’ 

direction, in Section 801 of EnPA, to 

issue public health and safety standards 

for protection of the public from 

releases of radioactive materials stored 

or disposed of in a potential repository 

at the Yucca Mountain site. Such 

standards were to be ‘‘based upon and 

consistent with’’ the findings and 

recommendations of the National 

Academy of Sciences (NAS). The NAS 

issued its findings and 

recommendations, on August 1, 1995, in 

a report entitled Technical Bases for 

Yucca Mountain Standards. 

The State of Nevada and other 

petitioners challenged both the EPA 

standards and the NRC regulations in 

court. On July 9, 2004, the United States 

Court of Appeals for the District of 

Columbia Circuit upheld both EPA’s 

standards and NRC’s regulations on all 

but one of the issues raised by the 

petitioners. See Nuclear Energy 

Institute, Inc. v. Environmental 

Protection Agency, 373 F.3d 1251 (DC 

Cir. 2004) (NEI v. EPA). The court 

disagreed with EPA’s decision to adopt 

a 10,000-year period for compliance 

with the standards and NRC’s adoption 

of that 10,000-year compliance period in 

NRC’s implementing regulations. The 

court found that EPA’s 10,000-year 

compliance period was not ‘‘* * * 

based upon and consistent with’’ NAS’ 

findings, as required by Section 801 of 

EnPA. See 373 F.3d at 1270. The NAS 

recommended EPA develop standards 

that provide protection when radiation 

doses reach their peak, within the limits 

imposed by long-term stability of the 

geologic environment. In addition, NAS 

found no scientific basis for limiting 

application of the individual-risk 

standard to 10,000 years. Thus, the 


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court vacated EPA’s rule, at 40 CFR Part 

197, to the extent that it specified a 

10,000-year compliance period, and 

remanded the matter to EPA. The court 

also vacated NRC’s rule, at 10 CFR Part 

63, insofar as it incorporated EPA’s 

10,000-year compliance period. 

EPA’s Proposed Rule 

In response to the remand, EPA 

proposed revisions (70 FR 49014; 

August 22, 2005) to elements of its 

standards affected by the court’s 

decision. EPA proposed to revise its 

individual-protection and humanintrusion standards to incorporate the 

time of peak dose into the determination 

of compliance. EPA retained its 0.15 

millisievert (mSv)/year [15 millirem 

(mrem)/year] standards for 10,000 years 

after disposal, and added a 3.5 mSv (350 

mrem) standard for the period after 

10,000 years, but within the period of 

geologic stability. EPA defined the 

period of geologic stability as ending at 

1 million years after disposal. Further, 

EPA proposed that NRC base its 

determination of compliance with the 

post-10,000 year standards, based on the 

median of the projected doses from 

DOE’s performance assessments, rather 

than on the arithmetic mean of the 

projected doses. The arithmetic mean 

was still retained as the compliance 

measure for the first 10,000 years after 

disposal. 

EPA also proposed to define how DOE 

should incorporate features, events, and 

processes (FEPs) in the performance 

assessment for the period after 10,000 

years. EPA explained that the goal of the 

performance assessment ‘‘is to design an 

assessment that is a reasonable test of 

the disposal system under a range of 

conditions that represents the expected 

case, as well as relatively less likely (but 

not wholly speculative) scenarios with 

potentially significant consequences. 

The challenge is to define the 

parameters of the assessment so that 

they demonstrate whether or not the 

disposal system is resilient and safe in 

response to meaningful disruptions, 

while avoiding extremely speculative 

(and in some cases, fantastical) events.’’ 

(70 FR 49048; August 22, 2005). EPA 

proposed that DOE’s performance 

assessments conducted to show 

compliance with the post-10,000 year 

individual protection and humanintrusion standards shall project the 

continued effects of the FEPs included 

in the initial 10,000 year analysis. EPA 

also proposed certain constraints on 

DOE’s performance assessments for the 

post-10,000 year period. These are: 

(1) Seismic analysis may be limited to 

the effects caused by damage to the 

drifts in the repository and the failure of 

the waste packages; 

(2) Igneous analysis may be limited to 

the effects of a volcanic activity event 

directly intersecting the repository, and 

the igneous event may be limited to that 

causing damage to the waste packages 

directly, causing releases of 

radionuclides to the biosphere, 

atmosphere, or ground water; 

(3) Climate change analysis may be 

limited to the effects of increased water 

flow through the repository as a result 

of climate change, and that the nature 

and degree of climate change may be 

represented by sampling within a range 

of specified constant conditions; and 

(4) DOE must assess the effects of 

general corrosion on engineered barriers 

and may use a constant representative 

corrosion rate throughout the period of 

geologic stability, or a distribution of 

corrosion rates correlated to other 

repository parameters. 

With respect to climate change, EPA 

further proposed that NRC shall specify 

in regulation the values to be used to 

represent climate change, such as 

temperature, precipitation, or 

infiltration rate of water. 

Finally, in its definition of ‘‘effective 

dose equivalent’’ EPA proposed that 

DOE calculate annual committed 

effective dose equivalents using the 

weighting factors that would be 

incorporated in its regulations in a new 

Appendix A to 40 CFR Part 197. EPA 

believes this reflects the most recent 

application of current radiation science 

to the calculation of dose. 

NRC’s Proposed Rule 

Under the EnPA, NRC’s regulations 

must be consistent with EPA’s 

standards. On September 8, 2005, NRC 

proposed revisions to its regulations 

designed to achieve consistency with 

EPA’s proposed revised standards (70 

FR 53313; September 8, 2005). NRC 

proposed to incorporate the new post10,000 year dose limit of 3.5 mSv/year 

(350 mrem/year) and statistical measure 

for compliance directly into its 

regulations for individual protection 

and human intrusion. Also, NRC 

proposed to adopt specific constraints 

EPA proposed for considering FEPs after 

10,000 years. NRC proposed to revise its 

requirements to be consistent with 

EPA’s proposal that the performance 

assessment for the first 10,000 years 

serve as the basis for projecting 

repository performance after 10,000 

years. NRC, supporting the use of 

current dosimetry, proposed to adopt 

the specific weighting factors provided 

in Appendix A of 40 CFR Part 197. 

Overall, NRC’s proposed changes to Part 

63 adopted the same or approximately 

the same wording as used by EPA in its 

proposed revisions to 40 CFR Part 197. 

Further, consistent with EPA’s 

specification of dosimetry for 

calculating individual doses to members 

of the public, NRC proposed to revise its 

Part 63 regulations to allow DOE to use 

the same methods for calculating doses 

to workers during the operational 

period. Finally, in response to EPA’s 

proposal, NRC proposed to specify, in 

its regulation, steady-state (constant-intime) values that DOE should use to 

project the long-term impact of climate 

variation. NRC proposed that DOE 

represent future climate change in the 

performance assessment by sampling 

constant-in-time deep percolation rates 

from a log-uniform distribution, which 

varies between 13 and 64 millimeters 

(mm)/year [0.5 and 2.5 inches (in.)/ 

year]. 

NRC’s notice of proposed rulemaking 

invited comments on its proposal to 

implement EPA’s proposed revisions to 

its standards, as well as on NRC’s 

revisions for use of specific weighting 

factors for calculating worker doses, and 

on NRC’s specification of values for 

climate change. NRC requested 

comments only on those provisions of 

Part 63 that NRC proposed to change 

and noted that its existing regulations 

were not affected by this rulemaking 

except insofar as NRC’s proposed rule 

adopts more up-to-date dosimetry for 

dose calculations. NRC notified 

potential commenters that comments on 

EPA’s revised standards should be 

directed to EPA. In response to requests 

from the public, NRC extended the 

comment period, originally ending on 

November 7, 2005, to December 7, 2005 

(70 FR 67098; November 4, 2005). 

II. Implementation of the 

Environmental Protection Agency’s 

Final Standards for a Compliance 

Period Beyond 10,000 Years and Within 

the Period of Geologic Stability 

EPA’s Final Rule 

EPA published final ‘‘Public Health 

and Environmental Radiation Protection 

Standards for Yucca Mountain, 

Nevada,’’ for the period after 10,000 

years at 40 CFR Part 197 on October 15, 

2008 (73 FR 61256). EPA has finalized 

its proposals relating to: consideration 

of FEPs in the post-10,000 year period, 

and use of specific weighting factors 

that reflect current methods of 

dosimetry and updated models for 

calculating individual exposures from 

radiation. EPA’s final rule differs from 

its proposal in two respects: the dose 

limit and the consideration of seismic 

activity. 


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First, the EPA standards establish a 

1.0 mSv/year (100 mrem/year) dose 

limit for the reasonably maximally 

exposed individual (RMEI) for the 

period after 10,000 years and within the 

period of geologic stability, rather than 

a 3.5 mSv/year (350 mrem/year) dose 

limit, as had been proposed. The EPA 

standards also provide that NRC base its 

determination of compliance with the 

post-10,000 year standards on the 

arithmetic mean of the projected doses, 

rather than on the median, as was 

proposed. 

Second, EPA’s standards now require 

that analyses of seismic activity 

consider water table rise under Yucca 

Mountain caused by seismic activity. 

The final standards specify that NRC 

may determine the magnitude of the 

water table rise to be used in the 

performance assessment for the period 

after 10,000 years or, if this magnitude 

is found to be insignificant, not require 

its consideration in performance 

assessment. Alternatively, NRC may 

require DOE to demonstrate the 

magnitude of the water table rise and its 

significance in terms of repository 

performance in its license application. 

NRC’s Final Rule 

EnPA directs the Commission to 

modify its technical criteria to be 

consistent with EPA’s standards for a 

geologic repository at the Yucca 

Mountain site. NRC’s final rule achieves 

this consistency by incorporating the 

revised standards into its final revised 

10 CFR Part 63 regulations as 

transparently as possible. A brief 

description of the Commission’s 

implementation of EPA’s standards 

follows: 

(1) For the period after 10,000 years 

and within the period of geologic 

stability (up to 1 million years), NRC 

adopts EPA’s 1.0 mSv/year (100 mrem/ 

year) dose limit for the RMEI in both the 

individual protection standard at 10 

CFR 63.311 and the human intrusion 

standard at 10 CFR 63.321. 

(2) NRC adopts, in 10 CFR 63.303, 

EPA’s specification of the arithmetic 

mean as the basis for determining 

compliance with the dose limit for the 

post-10,000-year period. 

(3) NRC adopts, in 10 CFR 63.305 and 

63.342, EPA’s specific requirements for 

the performance assessment DOE must 

use to evaluate the behavior of the 

repository for the period after 10,000 

years. The FEPs selected for use in the 

performance assessment for the first 

10,000 years should also be used for 

projecting repository performance after 

10,000 years. NRC adopts EPA’s 

additional constraints for the inclusion 

of seismic activity, igneous activity, 

climate change, and general corrosion in 

the performance assessment for the 

period of time after 10,000 years. The 

seismic analysis must include the 

magnitude of the water table rise and its 

significance on the results of the 

performance assessment unless NRC, 

through rulemaking, decides to specify 

the magnitude of the water table rise to 

be used in the performance assessment 

after 10,000 years or to not require its 

consideration. 

(4) NRC adopts, in 10 CFR 63.102(o), 

EPA’s specification of the weighting 

factors to be used for estimating 

potential radiation exposures for 

members of the public, which are 

provided in Appendix A of 40 CFR Part 

197. 

In addition to the changes made for 

consistency with EPA’s standards, NRC 

proposed to add a definition for 

‘‘weighting factor’’ and to amend 

§ 63.111(a)(1) to allow DOE to use the 

weighting factors in Appendix A for 

calculating doses to workers. After 

consideration of the public comments, 

NRC chooses not to add the proposed 

definition for ‘‘weighting factor’’ to its 

regulations nor to amend § 63.111(a)(1). 

Instead, NRC is providing a discussion 

regarding implementation of total 

effective dose equivalent (TEDE). NRC is 

adding text at § 63.102(o) to clarify that 

the weighting factors specified in EPA’s 

final standards should be used for dose 

calculations for workers and the public. 

Thus, TEDE calculations of potential 

radiation exposures to workers and the 

public are implemented consistently 

with a single set of weighting factors 

based on current dosimetry. The 

definition for TEDE is also revised to be 

consistent with NRC regulations at Part 

20. This approach avoids the 

unnecessary complication and potential 

confusion that could result from the use 

of different definitions in Parts 20 and 

63 and provides a single, clear statement 

on the proper implementation of TEDE 

in Part 63 thereby eliminating any need 

for further changes. (See response to 

comments under Use of Current 

Dosimetry, in this document.) 

EPA’s rule requires DOE to assess the 

effects of climate change in the period 

after 10,000 years. This assessment is 

limited to the effects of increased water 

flow through the repository. The nature 

and degree of climate change may be 

represented by sampling within a range 

of constant climate conditions. EPA 

leaves it to NRC to specify, in 

regulation, the values to be used to 

represent climate change, such as 

temperature, precipitation, or 

infiltration of water. NRC’s proposed 

rule sought public comment on its 

approach for representing the effect of 

future climate in performance 

assessments after 10,000 years. NRC 

proposed that the constant value to be 

used to represent climate change is to be 

sampled from a log-uniform distribution 

for deep percolation rates, which varies 

between 13 and 64 mm/year (0.5 and 2.5 

in./year). 

After consideration of the public 

comments received on its proposal, 

NRC’s final rule adopts its proposed 

approach with some modifications. NRC 

will require that DOE represent the 

effects of climate change by assuming 

constant-in-time climate conditions. 

The analysis may commence for the 

period beginning at 10,000 years after 

disposal and shall extend through the 

period of geologic stability. The 

constant-in-time value to be used to 

represent climate change is to be the 

spatial average of the deep percolation 

rate within the area bounded by the 

repository footprint. The constant-intime deep percolation rates to be used 

now to represent climate change shall 

be sampled from a ‘‘truncated’’ 

lognormal distribution for deep 

percolation rates, which varies between 

10 and 100 mm/year (0.39 and 3.9 in./ 

year). This ‘‘truncated’’ lognormal 

distribution has an arithmetic mean of 

37 mm/year (1.5 in./year) for the deep 

percolation rate as compared to an 

arithmetic mean of 32 mm/year (1.3 in./ 

year) based on the range and 

distribution in the proposed regulations. 

(See response to comments under 

Climate Change, in this document for 

further details on this approach and the 

consideration of public comments.) 

For a full description of changes NRC 

is incorporating into its Part 63 

regulations, see Section IV of this 

document. 

Water Table Rise From Seismic Activity 

NRC currently requires DOE to 

demonstrate the magnitude of the water 

table rise from seismic activity and its 

significance in its license application. 

The National Research Council (1992) 

conducted a comprehensive technical 

evaluation of mechanisms that could 

raise the water table at Yucca Mountain 

(National Research Council, Ground 

Water at Yucca Mountain: How High 

Can It Rise?, National Academy Press, 

Washington, DC, 1992). The Council 

considered both the dynamic response 

of the water table to propagation of 

seismic waves, as well as the long-term 

hydrologic response of the ground water 

system to permanent changes in rock 

stress after the seismic waves pass. The 

Council concluded that transient effects 

are not relevant to the performance of a 

repository. Of potential significance, 

however, are permanent changes to the 


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fluid pore pressure or rock permeability 

that may bring about long-term changes 

in the height of the water table. The 

report’s authors evaluated historical 

accounts of relevant large earthquakes 

that have caused long-term changes to 

the regional hydrologic regime of 

ground water systems. The authors 

conducted site-specific quantitative 

analyses of the potential change in the 

level of the water table. They concluded 

that ‘‘although the models are based on 

very limited data * * * [the] stress/ 

strain changes resulting from an 

earthquake are inadequate to cause more 

than a few tens of meters rise in the 

water table based on the convergence of 

the results by a variety of models and 

assumptions, especially if the deep 

carbonate aquifer is as incompressible 

as the limited data suggest.’’ Whatever 

approach DOE takes when determining 

the magnitude of the water table rise 

from seismic activity, NRC expects that 

DOE will consider the information 

provided by the National Research 

Council as referenced in the National 

Academy of Sciences report entitled, 

‘‘Technical Bases for Yucca Mountain 

Standards’’ (1995) at page 94 (i.e., 

‘‘Results indicate a probable maximum 

transient rise on the order of 20 m or 

less’’). 

Although EPA standards specify that 

NRC may determine the magnitude of 

water table rise and its significance, 

NRC is not planning such action. If, in 

the future, NRC decides to specify the 

magnitude of the water table rise and 

whether it is significant enough for 

consideration in DOE’s performance 

assessment, NRC will do so in a future 

rulemaking. 

III. Public Comments and Responses 

The NRC received 16 individual 

comment submittals, many of which 

contained numerous specific comments. 

In addition, NRC received more than 

3000 submissions objecting, in nearly 

identical text, to NRC’s adoption of 

EPA’s standards because the 

commenters believed the proposed 

standards are inadequate and because 

NRC published its proposed revision to 

Part 63 before EPA issued final 

standards. NRC carefully reviewed and 

considered the range of comments 

received during the public comment 

period. The NRC staff grouped the 

comments into the following five major 

topic areas: 

(1) NRC Adoption of EPA Standards; 

(2) Clarifications on NRC’s 

Implementation of FEPs for the 

Performance Assessment for the Period 

after 10,000 Years; 

(3) Climate Change; 

(4) Use of Current Dosimetry; and 

(5) Comments Beyond the Scope of 

this Rulemaking. 

1. NRC Adoption of EPA Standards 

Issue 1: Must NRC supplement EPA’s 

standards because they do not 

adequately protect public health and 

safety and the environment? 

Comment. Some commenters 

supported NRC’s adoption of EPA’s 

standards, while others opposed 

adoption because they believe EPA’s 

proposed standards are inadequate to 

protect public health and safety and the 

environment. The State of Nevada 

recognized that EnPA requires NRC’s 

regulations to be consistent with EPA’s 

standards but claims this does not mean 

the two must be identical. Rather, the 

State asserts, NRC must recognize that 

compliance with EPA’s standards is 

necessary but not sufficient to provide 

adequate protection of public health and 

safety and the environment. The State 

also asserts that NRC should promulgate 

supplemental standards, in its 

regulations, that will provide the 

additional protection the State believes 

is needed. With respect to EPA’s 

proposed standards, the State and other 

commenters particularly objected to 

EPA’s 3.5 mSv/year (350 mrem/year) 

post-10,000 year standard and use of the 

median to assess compliance. The State 

and other commenters also objected to 

many other features of the EPA 

standards, including limitations on the 

FEPs, use of a two-tier standard, and 

defining the period of geologic stability 

as ending at 1 million years. In support 

of its comments, the State attached a 

copy of the comments on the EPA 

proposed standards it had submitted to 

EPA. 

Response. While EnPA does not 

require NRC regulations to be identical 

to EPA’s, EnPA does direct the 

Commission to modify its technical 

criteria to be consistent with EPA’s 

standards for a geologic repository at the 

Yucca Mountain site. Thus, NRC is 

required to adopt EPA’s post 10,000 

year standard, and the NRC has done so. 

The NRC’s notice of proposed 

rulemaking notified potential 

commenters that comments such as 

these on EPA’s revised standards should 

be directed to EPA for EPA’s response. 

Issue 2: Should NRC extend the 

compliance period beyond 1 million 

years if it is determined that the peak 

dose may occur beyond the 1 millionyear period? 

Comment. The State commented that 

EPA’s requirement that the post-10,000 

year performance assessment should 

end at 1 million years is unnecessarily 

prescriptive. The State believes that if 

the trends in dose projection are not 

clear or heading upward and geologic 

stability is maintained, extending the 

assessment beyond 1 million years may 

be required to establish the performance 

of the entire repository system. The 

State believes that NRC has the 

authority to consider not only the 

magnitude of the peak, but also the 

timing and overall trends of dose 

projections as it evaluates the license 

application. 

Response. As explained in the 

response to the comment on Issue 1 

under NRC Adoption of EPA Standards 

of this document, EnPA requires the 

Commission to modify its technical 

criteria to be consistent with EPA’s 

standards for a geologic repository at the 

Yucca Mountain site. The NRC’s notice 

of proposed rulemaking notified 

potential commenters that comments 

such as these on EPA’s revised 

standards should be directed to EPA for 

EPA’s response. 

Issue 3: Has NRC illegitimately used 

rulemaking to resolve issues that must 

be resolved in an adjudicatory 

proceeding? 

Comment. The State of Nevada 

commented that the proposed rule 

violates fundamental principles of 

administrative law because it fails to 

conform to the usual distinctions in 

agency administrative processes 

between ‘‘rulemaking’’ and 

‘‘adjudication.’’ This is because the rule 

includes what the commenter believes 

to be ‘‘determinations of adjudicative 

fact’’ that apply only to Yucca Mountain 

and that should be matters adjudicated 

in NRC’s hearing on DOE’s license 

application. According to the 

commenter, there are two critical 

distinctions between rulemaking and 

adjudication: ‘‘First, a rule addresses the 

future while an order [the product of 

adjudication] addresses the past or the 

present. Second, a rule is based on 

general policy considerations or on 

what are sometimes called legislative 

facts, generalizations about people and 

things, while an order is based on 

specific facts about things and 

individuals, sometimes called 

adjudicative facts.’’ The commenter 

believes that the proposed rule violates 

this distinction because ‘‘[n]o agency 

may resolve a controversy over an 

adjudicative fact, relevant only to a 

single adjudication, by rulemaking.’’ 

The State further asserts that NRC’s 

alleged improper use of rulemaking to 

resolve adjudicatory factual issues 

constitutes an unlawful abrogation of 

Nevada’s right, under section 189 of the 

Atomic Energy Act of 1954 as amended 

(AEA), to an NRC licensing hearing on 

these factual issues. 


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1The rule does not, in fact, restrict consideration 

of corrosion in the post-10,000 year period to 

general corrosion; other types of corrosion, if 

important, will be carried over from the pre-10,000 

year period and will also be considered. 

In the State’s view, NRC cannot claim 

that it is permitted to resolve 

adjudicatory factual issues in its 

rulemaking simply because EPA did so 

and NRC must adopt EPA’s standards. 

The commenter recognizes that the 

EnPA alters a straightforward 

demarcation between rulemaking and 

adjudication because ‘‘EnPA does 

contemplate Yucca ‘rules’ that by their 

nature depend on some facts relevant 

only to Yucca.’’ However, the 

commenter contends that ‘‘EnPA 

authorized only those EPA findings of 

adjudicatory fact that (1) are based on 

what the [National] Academy [of 

Sciences] considered necessary to 

support an EPA rule; and (2) are 

essential to promulgate limits on 

radiation exposures, concentrations, or 

quantities beyond the boundary of the 

Yucca Mountain site.’’ This is because 

the grant of authority to EPA in EnPA 

to issue standards applicable only to 

Yucca Mountain is based on the 

previous delegation of rulemaking 

authority to EPA in section 121 of the 

Nuclear Waste Policy Act of 1982 

(NWPA), which, in turn, relies upon the 

delegation of authorities to EPA in 

Reorganization Plan Number 3 of 1970 

that identifies what standards EPA may 

issue. The commenter believes that the 

EPA standards that NRC is adopting are 

rife with ‘‘adjudicative facts’’ and go 

well beyond the narrow limits permitted 

by EnPA. 

The commenter cites eight 

‘‘determinations of adjudicative fact’’ 

that appear in NRC’s proposed rule, 

most of which NRC is adopting from 

EPA’s standards: 

(1) The performance assessment for 

the period after 10,000 years must use 

a time-independent log-uniform 

probability distribution for deep 

percolation rates of from 13 to 64 mm/ 

year; 

(2) Models and data used to develop 

FEPs (‘‘features, events and processes’’) 

for the assessment period before 10,000 

years are sufficient for the post-10,000- 

year assessment period; 

(3) Seismic analyses for the post10,000 year period may be based on 

seismic hazard curves developed for the 

pre-10,000-year period; 

(4) Seismic effects in the post-10,000- 

year period may be limited to effects on 

the repository’s drifts and waste 

packages; 

(5) Igneous effects in the post-10,000 

year period may be limited to effects on 

waste packages; 

(6) The effects of climate change in 

the post-10,000-year period may be 

limited to increased water flux through 

the repository; 

(7) Different types of corrosion of the 

waste packages must be considered in 

the pre-10,000-year period but only 

general corrosion at a constant rate may 

be considered in the post-10,000-year 

period; 1 and 

(8) Effects of climate change in the 

post-10,000-year period may be 

expressed by steady state (time 

independent) values. 

Response. The Commission disagrees 

with the comment. ‘‘It is a well-settled 

principle of administrative law that the 

decision whether to proceed by 

rulemaking or adjudication lies within 

the broad discretion of the agency. See, 

SEC v. Chenery Corp., 332 U.S. 194, 

202–03 (1947)’’ Wisconsin Gas 

Company v. Federal Energy Regulatory 

Commission, 770 F.2d 1144, 1166 (DC 

Cir. 1985). The Commission has 

properly exercised its discretion to 

resolve the issues referenced by the 

commenter through rulemaking rather 

than through adjudication. 

The commenter mischaracterizes as 

‘‘determinations of adjudicative fact’’ 

what are in reality assumptions, derived 

from data, testing, and scientific 

analysis, that DOE is to use in its 

performance assessment to demonstrate 

compliance with regulatory standards. 

A performance assessment is used to 

take account of the considerable 

uncertainties inherent in projecting 

disposal system performance over times 

as long as 1 million years. The 

performance assessment is not intended 

to resolve issues arising in the past or 

present. Rather, it is intended to provide 

a reasonable test of the safety of the 

repository by modeling through 

computer simulations a large number of 

‘‘alternative futures,’’ incorporating the 

features, events, and processes required 

by the rule to be included in the 

assessment to determine if there is a 

reasonable expectation that the disposal 

system will meet regulatory standards. 

The assumptions identified by the 

commenter impose certain limitations 

on the scope of the performance 

assessments. These limitations are based 

on the application of scientific 

reasoning to data, testing, and analysis 

at hand on these issues and are for the 

purpose of enabling a reasonable test of 

repository safety. 

NRC has made a policy judgment that 

rulemaking is the better procedural 

vehicle to use to determine how the 

performance assessments should be 

constructed and, in particular, what 

limitations are appropriate to avoid 

unbounded speculation and to provide 

a reasonable test of repository safety. 

How this testing should be conducted is 

preeminently a matter of scientific and 

technical analysis. To the extent that 

there may be disagreement in the 

scientific community as to the scientific 

soundness of the assumptions and any 

limitations on assumptions to be 

incorporated into the performance 

assessments, the notice and comment 

rulemaking process is of particular 

value because it allows equal access to 

all viewpoints and best assures 

achievement of the ultimate goal of 

making sure that the testing of the safety 

of the repository rests on the best 

science available. The determination of 

what assumptions and limitations on 

assumptions are best suited to form a 

reasonable test is not aimed at 

determining the rights or liabilities of 

particular individuals and thus, the 

adjudicatory process is not conducive to 

selecting the ingredients of the tests 

used to provide a reasonable 

expectation of repository safety. 

Because neither EPA nor NRC have 

made ‘‘determinations of adjudicative 

fact,’’ as explained above, the question 

of the extent of EPA’s authority under 

EnPA to establish standards through 

rulemaking that the commenter believes 

would otherwise be determinations of 

adjudicative fact does not arise. EPA has 

adequately addressed its jurisdiction to 

issue the standards that NRC is adopting 

in this final rule. 

The commenter may also be asserting 

that all the issues in this rulemaking are 

adjudicatory issues simply because the 

rule applies to only one entity, DOE, 

and the licensing of a repository at one 

site. A ‘‘rule,’’ as defined in the 

Administrative Procedure Act, ‘‘means 

the whole or part of an agency statement 

of general or particular applicability and 

future effect designed to implement, 

interpret, or prescribe law or policy’’ 5 

U.S.C. 551(4) (emphasis added). Thus, 

the fact that NRC’s rule applies only to 

DOE and only to DOE’s activities at one 

site does not, per se, turn the issues 

considered in this rulemaking into 

adjudicative issues determining 

adjudicative facts (See Attorney 

General’s Manual on the Administrative 

Procedure Act, 1947, p. 13 (‘‘[R]ule’’ 

includes agency statements not only of 

general applicability but also those of 

particular applicability applying either 

to a class or to a single person’’); 

Anaconda Company v. Ruckelshaus, 

482 F.2d 1301, 1306 (10th Cir. 1973)). 

The cases cited by the commenter, 

Heckler v. Campbell, 461 U.S. 458 

(1983), Broz v. Heckler, 711 F.2d 957 

(11th Cir. 1983) (Broz II), and Opinion 

Modified on Denial of Rehearing by Broz 


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2The Eleventh Circuit initially construed the 

provisions of the SSA in terms of the distinction 

between adjudicative facts and legislative facts and 

concluded that the effect of age on disability was 

an adjudicative fact that could not be determined 

in a rulemaking. Broz v. Schweiker, 677 F.2d 1351 

(11th Cir. 1982) (Broz I) Certiorari Granted, 

Judgment Vacated by Heckler v. Broz, 461 U.S. 952 

(1983). Upon remand for reconsideration in light of 

Campbell, the Eleventh Circuit, in Broz II, 

reaffirmed its original decision upon finding that 

the Supreme Court had left open the validity of the 

guidance with respect to its use in determining the 

effect of age on disability. 

3The commenter believes that the rules which 

resolve these issues will be incapable of actually 

being applied as written because they will turn out 

to be based on outdated scientific evidence. If this 

should happen, any person can petition to amend 

the rules. In addition, NRC’s procedural rules 

enable a party to an adjudicatory proceeding to 

petition that application of a rule be waived in 

circumstances when the rule would not serve the 

purposes for which it was adopted. See, 10 CFR 

2.335(b). 

v. Heckler, 721 F.2d 1297 (11th Cir. 

1983) (Broz III), in support of its view 

that NRC may not make ‘‘determinations 

of adjudicatory fact’’ in a rulemaking are 

similarly not relevant because no such 

determinations are being made in the 

final rule. These cases do not establish 

the broad principle stated by the 

commenter; i.e., that ‘‘[n]o agency may 

resolve a controversy over an 

adjudicative fact, relevant only to a 

single adjudication, by rulemaking.’’ In 

Heckler v. Campbell, the Supreme Court 

upheld the Secretary of Health and 

Human Service’s (HHS) reliance on 

rulemaking to establish guidance for the 

determination that jobs existed in the 

national economy within the capability 

of the disabled claimant against a claim 

that such a determination must be made 

in an individual adjudication. Broz 

considered the same guidance with 

respect to its application to the effect of 

age on disability determinations. 

Ultimately, in Broz III, the Eleventh 

Circuit of the U.S. Court of Appeals 

based its decision that this must be an 

individualized determination reached in 

an adjudication on its interpretation of 

Congress’ intent in amending the Social 

Security Act (SSA) rather than on more 

sweeping statements about an agency’s 

choice to use rulemaking or 

adjudication to achieve its mission.2

Finally, the Commission does not agree 

that resolving the issues the commenter 

has labeled ‘‘determinations of 

adjudicative fact’’ deprives the State of 

its right to a hearing under section 189a. 

of the AEA on these issues. As the 

Supreme Court has stated, ‘‘the statutory 

requirement for a hearing * * * does 

not preclude the Commission from 

particularizing statutory standards 

through the rulemaking process and 

barring at the threshold those who 

neither measure up to them nor show 

reasons why in the public interest the 

rule should be waived’’ (Federal Power 

Commission v. Texaco, Inc., 377 U.S. 

33, 39 (1964)).3

The commenter also believes that, as 

explained in its comments to EPA, 

EPA’s ‘‘findings of adjudicative fact,’’ in 

its final rule, now being adopted in 

NRC’s final rule, are without any 

technical basis and are contrary to 

sound science, and for that reason 

violate both EnPA and the AEA. The 

NRC’s notice of proposed rulemaking 

notified potential commenters that 

comments such as these on EPA’s 

revised standards should be directed to 

EPA for EPA’s response. 

Issue 4: Should NRC have waited to 

propose its regulations until after EPA 

had finalized its standards? 

Comment. A number of commenters 

objected to the process NRC used to 

conduct this rulemaking, namely 

issuing a proposed rule adopting EPA’s 

proposed standards before EPA issued 

its final standards. Commenters 

expressed the view that NRC conveyed 

the impression that EPA’s proposed 

standards would be adopted in NRC’s 

final rule, such that public comment on 

EPA’s proposal would have no effect; 

that if NRC cared what potential 

commenters thought about EPA’s 

proposal, it should have waited, 

considered the comments received by 

EPA, and developed NRC’s rule based 

on EPA’s final rule; that having the 

public comment period for both rules at 

the same time is confusing for 

concerned citizens and makes it 

difficult for them to comment on the 

NRC rule; and that NRC should provide 

an additional comment period on its 

rule if EPA’s final rule departs 

substantially from its proposed rule. 

Response. NRC’s process for 

conducting this rulemaking was 

intended to put in place revised 

regulations, consistent with EPA’s final 

revised standards, because the court had 

vacated NRC’s rule insofar as it 

incorporated EPA’s 10,000 year 

compliance period. NRC also sought to 

inform potential commenters on both 

rules, of how NRC envisioned 

implementing the EPA’s proposed 

standards. It was hoped that such 

information would be of value in 

developing comments on both 

proposals. NRC’s intention has always 

been, consistent with its statutory 

obligations, to conform its final 

regulations to the final standards EPA 

would issue after EPA duly considers 

the comments it received. 

NRC emphasized in its notice of 

proposed rulemaking that comments on 

EPA’s revised standards were to be 

addressed to EPA and that the scope of 

NRC’s revised rule was limited to its 

adoption of EPA’s revised standards, its 

proposal to allow DOE to use the same 

methods for calculating doses to 

workers during the operational period 

as those required for calculating public 

doses and its proposal to specify use of 

a deep percolation rate to represent the 

effect of future climate in performance 

assessments after 10,000 years. Thus, 

the narrow focus of NRC’s rulemaking 

only required potential commenters to 

focus on two technical issues beyond 

the issues involved in EPA’s proposal 

(i.e., setting a value for the deep 

percolation rate and use of modern 

dosimetry for estimating worker 

exposures). NRC extended the comment 

period by one month in response to 

public comments. For these reasons, we 

believe the public was given a fair 

opportunity to comment on NRC’s 

proposal. NRC regrets any 

misimpression that NRC was assuming 

that EPA’s proposed rule would become 

final as proposed without modification 

and that comments provided to EPA 

would have no effect. NRC made no 

such assumption and EPA has in fact 

made changes to its proposed rule in 

light of the comments it received. 

Finally, with respect to the request for 

an additional comment period if EPA’s 

final rule is substantially different from 

its proposed rule, as stated above (see 

Background section of this document), 

EPA’s final rule differs from its 

proposed rule in only two respects: the 

dose limit is set to 1.0 mSv/year (100 

mrem/year) with the arithmetic mean as 

the statistical metric to be used to assess 

compliance; and its requirement that 

NRC either establish the magnitude of 

the water table rise and its significance 

as part of the seismic assessment, or 

require DOE to do this assessment. The 

first change responds favorably to the 

numerous public comments urging use 

of a dose limit lower than 3.5 mSv/year 

(350 mrem/year) and use of the 

arithmetic mean as the measure of 

compliance. Similarly, in its final 

regulations, NRC requires DOE to 

include the magnitude of the water table 

rise and its significance in its seismic 

assessment submitted with the license 

application. As a result, this information 

would also be subject to litigation, 

absent any future NRC rulemaking on 

this subject. Because of these changes, 

the Commission believes there is no 

need for an additional comment period. 


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2. Clarification of NRC’s 

Implementation of FEPs for the 

Performance Assessment for the Period 

After 10,000 Years 

Issue 1: Are the FEPs considered for 

the first 10,000 years after repository 

closure the only FEPs that need be 

considered for the entire post-closure 

period? 

Comment. The Nuclear Energy 

Institute (NEI) agreed with NRC’s 

adoption of EPA’s requirement that the 

same FEPs identified and screened for 

inclusion in performance assessments to 

show compliance with the standards for 

the initial 10,000 years after closure be 

used in performance assessments to 

show compliance with the post-10,000 

year standards. However, NEI believes 

NRC should clarify that FEPs that are 

screened-in for the first 10,000 years 

after repository closure are the only 

FEPs that need be considered for the 

entire post-closure period. NEI provided 

the example that if DOE provides an 

adequate basis to screen-out postclosure criticality or microbiallyinfluenced corrosion (MIC) effects 

during the first 10,000 years after 

repository closure, the Yucca Mountain 

Review Plan (YMRP) should specify that 

no additional consideration of criticality 

or MIC in the post-10,000 year period is 

necessary. 

Response. The requirements for FEPs 

to be included in the performance 

assessment for the period after 10,000 

years are specified at § 63.342. DOE is 

required to include those FEPs that are 

screened into the performance 

assessments for the first 10,000 years 

after repository closure and the four 

FEPs specifically identified for 

inclusion, i.e., seismicity, igneous 

activity, climate change, and general 

corrosion. Based on the requirements at 

§ 63.342, the specific FEPs (criticality or 

MIC) identified by the commenter 

would only be included in the 

performance assessment after 10,000 

years if they were also included in the 

performance assessment for the first 

10,000 years (i.e., could not be screened 

out of the performance assessment for 

the first 10,000 years). The Commission 

does not believe further clarification to 

the regulation is necessary. 

Issue 2: Do the proposed changes to 

§ 63.114 ‘‘Requirements for performance 

assessment’’ impose additional limits on 

the performance assessment for the 

period after 10,000 years? 

Comment. The State of Nevada 

believes that § 63.114(b) appears to 

include another limit beyond the limits 

in § 63.342(c) on the post-10,000 year 

performance assessment and asks for 

clarification. NEI believes that NRC 

should more clearly assert that 

performance assessment methods 

meeting existing Part 63 requirements 

are also adequate for the post-10,000 

year period. 

Response. The changes to § 63.114 

impose no additional limits on the 

performance assessment for the period 

after 10,000 years. The changes ensure 

consistency between NRC’s regulations 

and EPA’s final standards. In particular, 

EPA’s final standards specify that FEPs 

used for the first 10,000 years should be 

used for estimating performance after 

10,000 years. Thus, § 63.114(b) specifies 

that the same performance assessment 

methods used for the first 10,000 years 

are to be used for the period after 10,000 

years. For example, parameter ranges 

used in the performance assessment for 

the first 10,000 years would be used in 

the performance assessment for the 

period after 10,000 years. Additional 

technical basis for selection of FEPs, 

beyond that developed for the 

performance assessment for the first 

10,000 years, is not required. Thus, the 

changes at § 63.114 ensure the 

performance assessment methods, such 

as the support and treatment of FEPs 

will be the same for the periods before 

and after 10,000 years, subject to the 

limits on performance assessments at 

§ 63.342. Some minor revisions have 

been made to § 63.114(b) to further 

clarify the Commission’s intent. 

Issue 3: Does the proposed treatment 

of a potential igneous event during the 

period after 10,000 years limit 

consideration of the effects of magma on 

spent fuel? 

Comment. The State of Nevada 

commented that the proposed regulation 

at § 63.342(c)(1)(ii) specifies that the 

effects of an igneous event are limited 

to the effects of damage directly to the 

waste package. The State is concerned 

that NRC will not consider the effects of 

magma on the radioactive waste inside 

the waste package. The State asserts that 

effects on the contents of the waste 

package could be important for igneous 

events that occur at times after waste 

packages are already breached because 

of other processes (such as corrosion) 

and the radioactive waste may be more 

vulnerable to igneous events. 

Response. The regulations do not 

exclude consideration of the spent fuel 

in the treatment of a potential igneous 

event during the period after 10,000 

years. The rule, at § 63.342(c)(1)(ii), 

requires the igneous analysis to include 

damage to the waste package directly. 

Waste package is defined in § 63.2 to 

mean ‘‘the waste form and any 

containers, shielding, packing, and 

other absorbent materials immediately 

surrounding an individual waste 

container’’ and waste form is defined in 

the same section to mean ‘‘the 

radioactive waste materials and any 

encapsulating or stabilizing matrix.’’ 

Thus, consideration of damage to the 

waste package would include 

consideration of damage to the 

radioactive waste materials inside the 

waste package. 

Issue 4: Should the seismic analysis 

exclude seismic activity from magma 

movement? 

Comment. NEI agreed with NRC’s 

proposal to limit analysis of long-term 

effects of seismicity to effects on the 

drifts in the repository and the waste 

package but requested that NRC clarify 

that seismic activity from magma 

movement need not be considered in 

the analysis. NEI suggests such a 

limitation is appropriate based on an 

Electric Power Research Institute (EPRI) 

analysis that demonstrates that seismic 

activity induced from magma movement 

is very minor, compared to seismic 

activity caused by tectonism. 

Response. Seismic activity includes 

activity from both tectonism and magma 

movement. Current methods to develop 

and quantify seismic ground motions, 

such as DOE’s current Probabilistic 

Seismic Hazard Assessment, include 

consideration of seismic activity from 

volcanism or magma movement. 

Volcanic sources of seismic activity are 

often included as part of the background 

seismic source term. Therefore, the 

commenter’s request for clarification, 

which would exclude seismic activity 

caused by magma movement from the 

seismic analysis, is not appropriate. 

Issue 5: Should NRC’s rule set a 

requirement for assuring the statistical 

significance of DOE’s modeling results 

in its performance assessments? 

Comment. The State of Nevada stated 

that NRC’s rule should establish a 

requirement for DOE to prove 

mathematically that its modeling results 

are statistically significant (i.e., a 

sufficient number of ‘‘runs’’ or the set of 

probabilistic simulations used to 

simulate the wide range of possible 

future behaviors of the repository 

system have been performed). 

Response. The current regulations 

provide specific requirements at 

§ 63.114 for the performance 

assessment. Among these, for example, 

are proper consideration of uncertainty 

and variability in parameter values. The 

Commission believes it is neither 

necessary nor appropriate to further 

specify measures of statistical 

significance. Fundamental to any 

approach for representing uncertainty 

and variability is demonstrating how the 

results accurately represent the 

uncertainty and variability, for example, 


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by performing a sufficient number of 

probabilistic simulations. Determining 

what number of ‘‘runs is sufficient’’ is 

best left for DOE to present and defend, 

based on the approach used in the 

performance assessment and an 

understanding of the results. NRC is 

confident that its regulations for 

performance assessment require DOE to 

provide sufficient information for NRC 

to judge if DOE has performed enough 

probabilistic simulations. 

Issue 6: Will FEPs associated with 

atmospheric releases of radioactivity 

and exposure of residents downwind of 

Yucca Mountain be considered in the 

performance assessment for the period 

after 10,000 years? 

Comment. Two commenters 

expressed concern over how FEPs 

associated with atmospheric releases of 

radioactivity and exposure of residents 

downwind of Yucca Mountain will be 

considered in the performance 

assessment for the period after 10,000 

years, including FEPs associated with 

seismic and igneous FEPs. 

Response. The performance 

assessment for the period after 10,000 

years must include consideration of 

potential atmospheric releases of 

radioactivity. The NAS report, 

Technical Bases for Yucca Mountain 

Standards (1995), pp. 6–7, 

recommended that the exposure 

scenario be specified in the standards 

because of the difficulties in projecting 

where people may reside and how 

exposures might occur in the distant 

future (e.g., thousands to hundreds of 

thousands of years in the future and 

longer). Accordingly, EPA specified 

characteristics of the RMEI (66–FR 

32134; June 13, 2001). 

Issue 7: Does the fact that the 

limitations on FEPs in the performance 

assessments are being established 

through rulemaking rather than 

adjudication, based on data available in 

2005, mean that there will be no 

flexibility to take into account data and 

models used in DOE’s license 

application or that DOE will have no 

incentive to further reduce 

uncertainties? 

Comment. The State of Nevada 

believes that the assumptions being 

used to account for uncertainty in the 

post-10,000 year period, and which are 

incorporated through this rulemaking 

into the limitations on the FEPs to be 

considered in DOE’s performance 

assessments, are premature and render 

the rule inflexible because they are 

based on data available in 2005. NRC’s 

rules must be sufficiently flexible to 

take into account data and models used 

in DOE’s license application. The State 

fears that because the rules are premised 

on uncertainties as perceived through 

2005 data and models, DOE will have a 

disincentive to reduce these 

uncertainties and add realism to its 

post-10,000 year performance 

assessment because it will wish to 

preserve the uncertainties and 

conservatisms that form the basis for the 

rules. 

Response. NRC’s regulations afford 

DOE the flexibility to account for 

uncertainty in data and models. Such 

flexibility provides neither incentive 

nor disincentive to reduce uncertainties. 

The regulations, at § 63.114, require 

DOE to account for the uncertainties in 

data and models in the performance 

assessment over the initial 10,000 years, 

and these same uncertainties are to be 

included in the performance assessment 

beyond 10,000 years. On June 3, 2008, 

DOE submitted a license application to 

NRC for authorization to construct a 

repository at Yucca Mountain. The NRC 

will review DOE’s treatment of the 

uncertainties. DOE has the flexibility to 

decide where to reduce uncertainties; 

however, it must demonstrate there is a 

reasonable expectation that the 

performance objectives will be met. 

NRC regulations afford DOE appropriate 

flexibility for selecting and supporting 

its performance assessment, including 

the consideration of uncertainties, given 

the unique and difficult task of 

estimating performance of a geologic 

repository over thousands of years. 

The regulations do provide certain 

limitations, as specified in EPA’s final 

standards, with respect to certain FEPs 

(i.e., seismicity, igneous activity, 

climate change, and general corrosion). 

Uncertainties in data and models for 

these FEPs are limited to those aspects 

of the FEPs considered most important 

to performance and the treatment of the 

uncertainties used in the performance 

assessment for the initial 10,000 years 

(see also the response to Issue 2 under 

this topic). For example, the 

consideration of seismic events in the 

performance assessment for the period 

after 10,000 years would be based on the 

same seismic hazard curve, including its 

uncertainties, that was used in the 

performance assessment for the initial 

10,000 years. However, the analysis for 

the period after 10,000 years would only 

consider the aspects of the seismic 

events that might be the most important 

to repository performance (i.e., damage 

to the drifts in the repository, failure of 

the waste package, and magnitude of the 

water table rise under Yucca Mountain). 

Finally, the commenter believes that 

the rules which resolve these issues will 

be incapable of actually being applied as 

written because they will turn out to be 

based on outdated scientific evidence. If 

this should happen, any person can 

petition to amend the rules. In addition, 

NRC’s procedural rules enable a party to 

an adjudicatory proceeding to petition 

that application of a rule be waived in 

circumstances when the rule would not 

serve the purposes for which it was 

adopted (See, 10 CFR 2.335(b)). 

3. Climate Change 

Issue 1: Can the future climatic regime 

be bounded by the observed range of 

conditions over past glacial-interglacial 

cycles? 

Comment. One commenter indicated 

it is incorrect to presume that future 

climate conditions at Yucca Mountain 

can be bounded by the observed range 

of conditions over past glacialinterglacial cycles. To the extent this 

comment may refer to human-induced 

influences on climate, those influences 

are considered under a separate issue. 

Response. The Commission believes 

the future climatic regime can be 

bounded by the observed range of 

conditions over past glacial-interglacial 

cycles. All climate predictions are based 

on and calibrated to evidence of past 

climates contained in the geologic 

record. The values specified for deep 

percolation rates adopted in the final 

regulation capture the range of temporal 

variability, uncertainty, and magnitude 

of deep percolation expected as a 

consequence of future climate change. 

The NAS committee (1995) was 

familiar with the science behind 

predicting future climate changes and 

stated, in its recommendations on Yucca 

Mountain standards, that a future ice 

age in the next few hundred years is 

‘‘unlikely but not impossible,’’ in the 

next 10,000 years is ‘‘probable but not 

assured.’’ However, over a 1-millionyear time frame, the climate is much 

more likely to pass through several 

glacial-interglacial cycles (i.e., ice ages). 

The NAS indicated there is a reasonable 

data base from which to infer past 

changes and noted that ‘‘(a)lthough the 

range of climatic conditions has been 

wide, paleoclimate research shows that 

the bounding conditions, the envelope 

encompassing the total climatic range 

have been fairly stable’’ and that 

‘‘(b)ased on this record, it seems 

plausible that the climate will fluctuate 

between glacial and interglacial stages 

during the period suggested for the 

performance assessment calculations.’’ 

Further, in its 1995 findings, the NAS 

stated that ‘‘enough of the important 

aspects [of climate change] can be 

known within reasonable limits of 

uncertainty, and these properties and 

processes are sufficiently understood 

and stable over the long time scales of 

interest to make calculations possible 


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and meaningful, we believe that there is 

a substantial scientific basis for making 

such calculations, taking uncertainty 

and natural variability into account.’’ 

Issue 2: Should human-induced 

influences on climate be considered 

when bounding the future climatic 

regime? 

Comment. One commenter noted that 

human-induced (i.e., anthropogenic) 

influences on climate from fossil fuel 

combustion and the resulting 

persistence of greenhouse gases in the 

atmosphere are the main issues to 

consider in predicting future climatic 

conditions. These anthropogenic effects 

might cause substantial reorganization 

of atmospheric systems, both before and 

after 10,000 years, that increase the 

number and intensity of extreme storm 

events at Yucca Mountain. The 

commenter believed that the highly 

non-linear hydrologic response of an 

arid system like Yucca Mountain to 

such extreme events would affect the 

performance of the repository and 

invalidate the use of the long-term 

average climate proposed in the Part 63 

revisions. The same commenter also 

noted that the predictive challenges of 

simulating these postulated extreme 

events could be met through use of 

existing and soon-to-be-available global 

circulation models (GCMs) that 

explicitly incorporate atmospheric 

composition and evolution in predicting 

future climate conditions. In presuming 

use of these models, this commenter 

noted that uncertainties in climate 

prediction do not change in the period 

beyond 10,000 years, at least in terms of 

the range of climate conditions that 

could occur, but rather that their 

detailed timing may change. Another 

commenter speculated that the same 

anthropogenic climate effects might 

delay the onset and reduce the 

magnitude of full glacial cycles, 

resulting in longer interglacial periods 

that would be warmer and drier than 

present-day conditions. Accordingly, 

this second commenter felt that the use 

of long-term average climate conditions 

represented by the values specified for 

deep percolation rates in the proposed 

Part 63 revisions was overly 

conservative and that less water would 

reach the repository horizon. 

Response. NRC considered the effects 

of anthropogenic influences on climate 

change. Based on that evaluation, the 

NRC believes the range of values 

specified for deep percolation rates 

adopted in the final rule captures the 

range of temporal variability, 

uncertainty, and magnitude of deep 

percolation expected as a consequence 

of future climate change. 

The magnitude and timing of the 

anthropogenic effects suggested by the 

commenter are likely to be more 

pronounced during the first 10,000 

years. The final regulation addresses 

only the 10,000 to 1 million year time 

period, during which any anthropogenic 

effects are anticipated to diminish. 

Anthropogenic effects, as represented in 

the GCMs cited by the commenter, 

might persist for 100,000 year time 

periods, but they do not fluctuate 

periodically and they decrease with 

time after an initial peak. Therefore, 

NRC believes that these effects can be 

captured by the long-term average 

infiltration values adopted in the final 

regulation because the range of values 

for the sampled population bounds 

these effects in an appropriately 

conservative manner. 

Atmospheric reorganization and 

increased frequency and magnitude of 

extreme events might result from 

natural or anthropogenic climate 

change. However, extreme 10-to 20-year 

events effectively become long-term 

averages that are incorporated into the 

range specified for deep percolation in 

the final regulation, when simulating a 

time period of 1 million years. 

The Paintbrush non-welded tuff unit 

(PTn unit) overlying the potential 

repository dampens the effects of 

transient phenomena associated with 

shorter time frames (Manepally, C., et 

al., ‘‘The Nature of Flow in the Faulted 

and Fractured Paintbrush Nonwelded 

Hydrogeologic Unit,’’ San Antonio, TX: 

Center for Nuclear Waste Regulatory 

Analyses, April 2007) in the system’s 

response to external hydrologic events. 

The NAS also recognized that long-term 

net infiltration averages can bound and 

describe Yucca Mountain hydrology 

adequately, stating that ‘‘the subsurface 

location of the repository would provide 

a temporal filter for climate change 

effects on hydrologic processes’’ The 

commenter also acknowledged this, 

quoting Cohen, ‘‘no evidence shows that 

high-frequency fluctuations (a few years 

or shorter) penetrate to the depth of the 

potential repository’’ (Cohen, S., 

‘‘Assumptions, Conservatisms, and 

Uncertainties in Yucca Mountain 

Performance Assessments,’’ S. Cohen & 

Associates, prepared for U.S. 

Environmental Protection Agency, 

August 8, 2005). Flow simulations have 

shown that the non-welded PTn rock 

unit effectively damps out decadal flow 

transients. Also, as the first commenter 

notes, ‘frequent events’ are mitigated by 

evapotranspiration. If high-precipitation 

events occur more frequently, the 

concomitant increases in soil formation 

and vegetation likely will mitigate the 

potential for increased infiltration, 

because net infiltration correlates 

inversely with soil thickness and extent 

of vegetative cover. Given the expected 

ratios of infiltration to precipitation, 

infiltration estimates of 15 to 60 mm 

(0.6 to 2.4 in.) per event would result if 

all precipitation were to infiltrate. In 

reality, a substantial fraction of such 

high precipitation will run off or 

evapotranspire. Accordingly, long-term 

deep percolation as specified in the 

proposed rule captures these events in 

an appropriately conservative manner. 

The points raised by the second 

commenter illustrate the divergence of 

scientific opinions about the nature and 

magnitude of natural and 

anthropogenically influenced climate 

change, particularly at the sub-regional 

scale necessary for net infiltration 

predictions at Yucca Mountain. The 

natural and anthropogenic effects 

associated with climate change are 

uncertain at this scale. Predictions will 

vary in timing, frequency, and 

magnitude of climatic variables such as 

temperature and precipitation, and 

therefore, net infiltration and deep 

percolation. The first commenter notes 

that climate change might result in 

wetter conditions resulting in 

insufficiently conservative predictions; 

the second commenter is concerned that 

conditions at Yucca Mountain might be 

drier in the future, resulting in overly 

conservative predictions. The first 

commenter refers to Cohen (2005) with 

respect to certain aspects of this issue; 

however, Cohen (2005) also notes that 

‘‘(a)nthropogenic climate changes could 

reduce possibility of future glacial 

climates, lowering long-term infiltration 

rates and reducing dose.’’ 

In conclusion, the range of 

uncertainty and variability in 

predictions of future climate, including 

that associated with anthropogenic 

changes, and the resulting deep 

percolation are captured by the range of 

values specified in the final regulation. 

Issue 3: Is the nature and extent of the 

future climatic regime reasonably 

represented by the stylized scenario 

where constant climate conditions take 

effect after 10,000 years and continue 

through the time of geologic stability? 

Comment. Some commenters were 

concerned about the proposed future 

climate scenario, in which the future 

climate is represented by constant-intime conditions that take effect after 

10,000 years and continue through the 

time of geologic stability. The 

commenter’s general concern is that 

assuming constant conditions may 

underestimate the hydrologic response 

at Yucca Mountain by failing to 

consider explicitly either variable dry 

and wet periods or changes in soils, 


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vegetation, and the watershed 

geomorphic characteristics in 

performance assessments over the time 

of geologic stability. Specifically, one 

commenter states that using constant-intime infiltration rates is nonconservative because a performance 

assessment conducted with this 

assumption would underestimate doses 

to the RMEI. The stated basis for this 

conclusion is that transient changes 

from dry to wet conditions in the 

repository cause greater radionuclide 

releases because localized corrosion of 

the waste packages is more likely under 

drier conditions. Also the exposed 

waste form is more likely to be 

dissolved and radionuclides are more 

apt to be transported to the biosphere 

under subsequent wet conditions. 

Response. The range and distribution 

of deep percolation rates adopted in the 

final regulations appropriately reflect 

the uncertainty in the area-averaged 

water flux through the footprint of the 

potential repository during the period 

after 10,000 years and are a reasonable 

basis for estimating and evaluating the 

long-term safety of the repository. 

The range and distribution of deep 

percolation rates adopted in the final 

regulation are not, in fact, based on 

constant climate conditions. The 

technical bases for the deep percolation 

range subsume time-variant climate 

conditions, whose future periodicity 

and magnitude are based on and 

calibrated to the range of conditions 

preserved in the geologic record, which 

includes geomorphic changes. In 

addition, the hydrogeologic properties 

of the PTn unit overlying the repository 

horizon, where present, dampen the 

magnitude of short term fluctuations in 

deep percolation that might be 

associated with future climate change or 

variability in precipitation (Manepally, 

C., et al., ‘‘The Nature of Flow in the 

Faulted and Fractured Paintbrush 

Nonwelded Hydrogeologic Unit,’’ San 

Antonio, TX: Center for Nuclear Waste 

Regulatory Analyses, April 2007). NAS 

acknowledges the phenomenon by 

indicating that ‘‘(t)he subsurface 

location of the repository would provide 

a temporal filter for climate change 

affects on hydrologic responses. For this 

reason, climate changes lasting on the 

order of hundreds of years would have 

little, if any, effect on repository 

performance.’’ 

The commenter’s argument that doses 

to the RMEI would be underestimated 

appears to be based on results from 

preliminary performance assessments 

conducted by DOE in which localized 

corrosion is the predominant mode of 

waste package failure. Preliminary 

waste package models developed by 

DOE indicate that the Alloy 22 outer 

container is susceptible to localized 

corrosion predominantly during the first 

few thousands of years, when waste 

package temperatures are high and 

concentrated solutions could develop. 

At times beyond 10,000 years, when 

waste package temperatures are lower, 

the relative humidity within the 

emplacement drift is high, and solutions 

are less concentrated; the waste package 

is less susceptible to localized 

corrosion. Because general corrosion 

appears to be the dominant mode of 

waste package failure after 10,000 years, 

precise modeling of transient changes 

from drier to wetter conditions is 

unlikely to have a pronounced effect on 

peak expected dose. 

The commenter’s argument does not 

appear to consider 10 CFR 63.303, 

which states that ‘‘compliance is based 

upon the mean of the distribution of 

projected doses of DOE’s performance 

assessments.’’ The 1995 NAS document 

at page 77 concluded that ‘‘[a]lthough 

the typical nature of past climate change 

is well known, it is obviously 

impossible to predict in detail either the 

nature or the timing of future climate 

change.’’ Although the science of 

climatology has advanced significantly 

in the 15 years after the publication of 

the NAS report, predicting the timing of 

dry-to-wet transitions remains highly 

uncertain. Even if it were true that 

‘‘[p]eak dose is likely to occur when a 

wet period follows a long period of 

unusually dry conditions’’ as indicated 

by the commenter, dry-to-wet transients 

in performance assessments would have 

less influence on the mean of the 

distribution of projected doses than on 

any single projected dose used to 

construct the distribution. Specifically, 

simulations done by the NRC using its 

performance assessment code (TPA 

Version 4.1j) exhibited similar 

repository performance, in terms of 

dose, under constant and non-constant 

climate scenarios (‘‘Regulatory 

Perspective on Implementation of a 

Dose Standard for a One-Million Year 

Compliance Period,’’ T. McCartin, 

Proceedings of the 2006 Materials 

Research Society Fall Meeting, Volume 

985 from the Materials Research Society 

Proceedings Series). In these 

simulations, the non-constant climate 

scenarios were developed using cyclic 

variations caused by orbital parameters. 

Also, the constant climate scenarios 

used deep percolation values specified 

in NRC’s proposed regulations. 

Performance assessment models and 

analyses continue to improve; however, 

dry-to-wet conditions appear to have a 

limited effect on the mean dose within 

the constraints of current performance 

assessment approaches. 

Issue 4: What is the range of future 

mean annual precipitation rates used to 

estimate future mean annual deep 

percolation rates? 

Comment. The State of Nevada 

commented that the upper bound of the 

future precipitation rate stated in the 

discussion section preceding the 

proposed regulation is lower than that 

used by DOE. DOE commented that the 

precipitation rates discussed in the 

proposed regulation do not represent 

the full range of expected climates. The 

Advisory Committee on Nuclear Waste 

suggested including additional 

documentation in the final rule for the 

approach used to calculate average 

precipitation rates over the post-10,000 

year period. 

Response. NRC has conducted 

detailed climate analyses that 

considered time-varying values of 

historic, inferred prehistoric, and 

potential future precipitation rates to 

support the range of long-term-average 

future deep percolation rates adopted in 

the final regulations. These time-varying 

precipitation rates were also used to 

estimate the range and bounds of 1- 

million-year-average annual 

precipitation. Having considered the 

comments and conducted further 

analyses, the Commission believes the 

time-varying precipitation rates used to 

estimate future mean annual deep 

percolation rates are appropriate. 

The lowest and highest values of the 

1-million-year-average future annual 

precipitation in any climate sequence 

used to estimate the 1-million-yearaverage future deep percolation rate are 

211 and 471 mm/year (8.3 and 18.5 in./ 

year) at a 1,524 meter (5,000 foot) 

reference elevation. NRC used two 

approaches, which are described by 

Stothoff and Walter, ‘‘Long-Term 

Average Infiltration at Yucca Mountain, 

Nevada: Million-Year Estimates,’’ San 

Antonio, TX: Center for Nuclear Waste 

Regulatory Analyses (2007), to estimate 

time-varying sequences of mean annual 

precipitation that vary over glacial 

cycles. Both approaches estimate 

precipitation for glacial stages, with the 

sequence of glacial stages determined 

using well-known orbital dynamics 

relationships. The first approach is 

based on the climate reconstruction by 

Sharpe, ‘‘Future Climate Analysis: 

10,000 Years to 1,000,000 Years After 

Present,’’ Reno, NV: Desert Research 

Institute (2003), with present-day and 

monsoon climatic conditions adjusted 

to reflect historical precipitation 

measurements in the vicinity of Yucca 

Mountain based on meteorological data 

in Bechtel SAIC Company (BSC), 


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4The truncated lognormal distribution is based 

on a lognormal distribution with an arithmetic 

mean of 41 mm/year (1.6 in./year) and a standard 

deviation of 33 mm/year (1.3 in./year). The 5th and 

95th percentiles of this lognormal distribution are 

approximately 10 and 100 mm/year (0.39 and 3.9 

in./year), respectively. 

‘‘Simulation of Net Infiltration for 

Present-Day and Potential Future 

Climates,’’ Las Vegas, NV: Bechtel SAIC 

Company, LLC (2004). The 1-millionyear-average mean annual precipitation 

rate from the first approach ranges from 

213 to 389 mm/year (8.4 to 15.3 in./ 

year), and with a mean of 315 mm/year 

(12.4 in./year) and a standard deviation 

of 52 mm/year (2.0 in./year). The second 

approach is based on estimated 

sequences of future continental ice 

volumes, which respond to insolation 

variation caused by orbital dynamics, 

with changes in precipitation related to 

changes in atmospheric patterns 

occurring from changes in continental 

ice volume. The 1-million-year-average 

mean annual precipitation for the 

second approach ranges from 211 to 471 

mm/year (8.3 to 18.5 in./year), and with 

a mean of 322 mm/year (12.7 in./year) 

and a standard deviation of 47 mm/year 

(1.8 in./year). 

Both approaches described by 

Stothoff and Walter, ‘‘Long-Term 

Average Infiltration at Yucca Mountain, 

Nevada: Million-Year Estimates,’’ San 

Antonio, TX: Center for Nuclear Waste 

Regulatory Analyses (2007) subdivide 

the 1-million-year period into a 

sequence of interglacial and glacial 

stages that vary in duration from 500 to 

40,000 years. For each stage, a range of 

mean annual precipitation is estimated 

that includes uncertainty. The smallest 

and largest values of estimated mean 

annual precipitation considered in any 

stage are 162 and 581 mm/year (6.4 and 

22.9 in./year). 

Issue 5: What is the range of future 

deep percolation rates? 

Comment. A number of commenters 

endorsed the approach of specifying the 

rate of water flow through the Yucca 

Mountain repository (expressed as deep 

percolation rate) as an appropriate and 

practical approach to adopting EPA’s 

requirement to consider the effect of 

climate variation after 10,000 years. 

Several commenters indicated that the 

basis for the proposed regulation was 

not clearly explained. Also, several 

commenters questioned the specific 

range of deep percolation rates 

discussed in the proposed regulation. 

The State of Nevada raised a number of 

additional concerns. First, the State 

questioned the validity of estimating 

infiltration using a constant climate 

state. Second, the State questioned the 

range of uncertainty used to represent 

infiltration for present-day and future 

climate in the long-term-average 

estimates. Third, the State questioned 

the adequacy of computer models (e.g., 

one-dimensional models without lateral 

distribution) to extrapolate net 

infiltration values to future climates. 

Fourth, the State questioned the 

assumption that plant and soil regimes 

remain stationary during future climate 

states. Another commenter was 

concerned with the assumption that 

spatial variability of infiltration remains 

constant over time. NEI commented that 

requiring climate to be assumed 

constant at present-day conditions over 

the post-10,000 year period would be a 

more appropriate implementation of a 

stylized approach. NEI also considered 

the range of 5 to 20 percent for the ratio 

of the deep percolation rate to 

precipitation rate, used to support the 

deep percolation rates in the proposed 

rule, was too large and provided an 

alternative range of 5 to 10 percent. DOE 

commented that deep percolation rates 

appear to be skewed to the maximum 

deep percolation rate rather than a rate 

obtained from the full range of expected 

climate. 

Response. Having considered the 

comments and conducted further 

analyses, the final regulations specify a 

slightly different range for the deep 

percolation rate from the proposed rule. 

The final rule now specifies that deep 

percolation rates averaged over the 

period of 10,000 to 1 million years in 

the future may be reasonably described 

with a‘‘truncated’’ lognormal 

distribution,4 which varies between 10 

and 100 mm/year (0.39 and 3.9 in./ 

year). To address commenters’ concerns 

with respect to certain simplifying 

assumptions used to estimate the deep 

percolation rates (e.g., range of 5 to 20 

percent for the ratio of the deep 

percolation rate to precipitation rate) the 

NRC has conducted more sophisticated 

analyses, which are now used to 

support the estimates for the deep 

percolation rates. The distribution of 

deep percolation rates is based on the 

analysis of Stothoff and Walter, ‘‘LongTerm Average Infiltration at Yucca 

Mountain, Nevada: Million-Year 

Estimates,’’ San Antonio, TX: Center for 

Nuclear Waste Regulatory Analyses 

(2007), who estimated deep percolation 

areally averaged within a rectangle 

overlying the repository footprint 

considering uncertainty in both climate 

and net infiltration. The analysis 

suggested that long-term-average deep 

percolation is better represented by a 

‘‘truncated’’ lognormal distribution than 

the originally proposed log-uniform 

distribution that ranged from 13 to 64 

mm/year (0.5 to 2.5 in./year). The NRC 

adopted a ‘‘truncated’’ lognormal 

distribution between the 5th and 95th 

percentiles of the lognormal distribution 

to represent reasonable lower and upper 

limits for the long-term average deep 

percolation rates. The revised 

distribution for deep percolation is 

consistent with available deep 

percolation estimates from Yucca 

Mountain, recharge estimates from a 

wide range of elevations in central and 

southern Nevada, and uncertainty 

estimates from a numerical model. The 

‘‘truncated’’ lognormal distribution has 

an arithmetic mean of 37 mm/year (1.5 

in./year) for the deep percolation rate as 

compared to an arithmetic mean of 32 

mm/year (1.3 in./year) based on the 

range and distribution in the proposed 

regulations. Although the upper limit of 

the deep percolation rate [i.e., 100 mm/ 

year (3.9 in./year)] in final regulations is 

almost twice the upper limit in the 

proposed regulation [i.e., 64 mm/year 

(2.5 in./year)], the deep percolation rates 

in the final regulations, on average, 

represent only slightly wetter conditions 

than what was specified in the proposed 

regulations [i.e., arithmetic mean of 37 

versus 32 mm/year (1.5 versus 1.3 in./ 

year)]. Truncation of the lognormal 

distribution between 10 and 100 mm/ 

year (0.39 and 3.9 in./year) results in 

reasonable lower and upper limits for 

the long-term average deep percolation 

rates. If the lower and upper limits were 

extended further, the resulting 

arithmetic mean of the distribution 

would change very little because of the 

decreasing probability of values that 

occur at the tails (or extremes) of a 

lognormal distribution. 

To document more clearly the 

technical bases for the proposed range 

of long-term-average future deep 

percolation rates expected at Yucca 

Mountain during the post-10,000 year 

period, the NRC conducted additional 

detailed climate and infiltration 

analyses, which are reported in Stothoff 

and Musgrove, ‘‘Literature Review and 

Analysis: Climate and Infiltration,’’ San 

Antonio, TX: Center for Nuclear Waste 

Regulatory Analyses (2006) and Stothoff 

and Walter (2007). Stothoff and 

Musgrove (2006) provide a 

comprehensive review and analysis of 

relevant infiltration and recharge 

studies that have been conducted for the 

Yucca Mountain region, the Death 

Valley region, the southern and central 

Great Basin of Nevada, and analogous 

arid to semi-arid regions in the western 

United States and the world. Stothoff 

and Walter (2007) describe additional 

technical investigations of estimated 

precipitation rates and temperatures for 

the past 1 million years in the Yucca 


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Mountain region based on various 

climate proxy data reported in the 

literature. Stothoff and Walter (2007) 

link these past precipitation and 

temperature estimates with a wellaccepted glacial model based on orbital 

dynamics to estimate precipitation and 

temperature sequences for the next 1 

million years. Finally, Stothoff and 

Walter (2007) use these future climate 

sequences with infiltration relationships 

supported by the data described in 

Stothoff and Musgrove (2006) and site 

observations at Yucca Mountain to 

estimate the range of long-term-average 

future deep percolation rates at Yucca 

Mountain during the post-10,000 year 

period. 

Contrary to inferences made by the 

State of Nevada, the revised distribution 

for deep percolation does not use 

steady-state hydrology based on annual 

average precipitation to estimate deep 

percolation. Stothoff and Walter (2007) 

considered the time-varying response of 

net infiltration to precipitation at time 

scales ranging from individual 

precipitation events, to decadal-scale 

averages, to millennial-scale glacial 

stages to derive estimates of long-termaverage deep percolation. 

Stothoff and Walter (2007) considered 

the response of net infiltration to 

climate at approximately 16,000 

locations across Yucca Mountain to 

derive estimates of long-term-average 

deep percolation averaged over the 

repository footprint. Uncertainty in each 

of the hydraulic and climatic factors 

affecting infiltration was considered at 

each of the 16,000 locations. Stothoff 

and Walter (2007) found that a 

lognormal distribution for areal-average 

net infiltration reasonably reflects the 

effect of the uncertainty in these factors. 

Stothoff and Walter (2007) did not use 

the INFIL version 2 model developed by 

the U.S. Geological Survey (USGS) for 

this analysis, nor did they neglect lateral 

redistribution of runoff. 

The State of Nevada questioned the 

appropriateness of using a stationary 

hydrologic state to describe plant and 

soil characteristics in numerical 

modeling and another commenter was 

concerned with the assumptions that 

the spatial variability of infiltration 

remains constant over time. The deep 

percolation model described by Stothoff 

and Walter (2007) does not use a 

stationary description for plant uptake. 

It does use a stationary description for 

soil characteristics but recognizes that 

soil thicknesses and soil texture may 

change over a glacial cycle. Stothoff and 

Walter (2007) consider the likely 

influence of such changes on net 

infiltration to be relatively small 

compared to the overall uncertainty in 

net infiltration. Soil evolution under 

glacial conditions will tend to deepen 

soil profiles over time and make the soil 

texture finer than at the present time, 

which would tend to reduce net 

infiltration at the end of a long, wetter 

glacial interval. Soil cover tends to 

erode under interglacial conditions, 

which may promote net infiltration 

during dry intervals. NRC considers it 

reasonable to neglect soil evolution 

because soil evolution would tend to 

make net infiltration under both glacial 

and interglacial climatic states more like 

the long-term-average infiltration. 

Although soil properties are stationary 

in the deep percolation model in 

Stothoff and Walter (2007), plant uptake 

is not and therefore the spatial 

variability of deep percolation in the 

model of Stothoff and Walter (2007) is 

not constant over time. 

NEI commented that the 1-millionyear-average deep percolation rates used 

for performance assessments should be 

maintained at present-day values 

because this would be more 

conservative with respect to 

groundwater usage for dose calculations 

for the RMEI. Deep percolation rates in 

Yucca Mountain do not affect the 

groundwater usage rate of the RMEI for 

evaluating compliance with the post10,000 year individual protection 

standard. Groundwater usage rates at 

the location of the RMEI as prescribed 

at 10 CFR 63.312(c) are fixed at an 

annual water demand of 3.7 million 

cubic meters (3,000 acre-feet). DOE 

commented that, considering the 

analyses by Sharpe ‘‘(Future Climate 

Analysis: 10,000 Years to 1,000,000 

Years After Present,’’ Reno, NV: Desert 

Research Institute, 2003), the proposed 

probability distribution was skewed 

towards maximal percolation rates 

because the full range of potential 

climates was not considered in the 

regulation. Stothoff and Walter (2007) 

compared net infiltration estimates 

using potential future climate sequences 

obtained from an independent model 

based on site and regional observations 

and a global ice volume model, and 

sequences obtained from a slightly 

modified version of the Sharpe (2003) 

model. The Sharpe (2003) model was 

modified to update the present-day 

climate with site-specific present-day 

climate observations from BSC 

(‘‘Simulation of Net Infiltration for 

Present-Day and Potential Future 

Climates,’’ Las Vegas, NV: Bechtel SAIC 

Company, LLC, 2004). The modified 

Sharpe model yields an estimate for 

long-term-average deep percolation with 

a mean value of 44 mm/year (1.7 in./ 

year) and values of 9.9 and 103 mm/year 

(0.39 and 4.1 in./year) at the 5th and 

95th percentiles, respectively. The 

independent model, which was used to 

specify the deep percolation 

distribution in the regulation, has a 

mean value of 41 mm/year (1.6 in./year) 

and values of 10 and 102 mm/year (0.39 

and 4.0 in./year) at the 5th and 95th 

percentiles, respectively. Because the 

two independent climate sequences 

consider a wide range of potential 

climates yet yield similar infiltration 

estimates, the NRC believes the 

distribution of deep percolation rates 

adopted in the final regulation is not 

skewed toward maximal percolation 

rates. 

Issue 6: Is the NRC guidance 

document on uncertainty and analysis 

of infiltration and subsurface flow and 

transport, intended for Site 

Decommissioning Management Plan 

(SDMP) sites, applicable to establishing 

an appropriate stylized climate scenario 

for times beyond 10,000 years at the 

potential high-level radioactive waste 

(HLW) disposal site at Yucca Mountain? 

Comment. One commenter noted 

there is no clear indication whether or 

how NRC’s existing guidance on 

accounting for uncertainty when 

establishing infiltration rates has been 

applied. Specifically, the commenter 

referred to NUREG/CR–6565, 

‘‘Uncertainty Analysis of Infiltration 

and Subsurface Flow and Transport for 

SDMP Sites’’ (1997). 

Response. The guidance presented in 

NUREG/CR–6565 is intended to be used 

only at SDMP sites. Therefore, NUREG/ 

CR–6565 is not directly applicable to a 

potential high-level waste disposal site. 

However, the methods NRC uses to 

account for uncertainty in its 

independent estimate of infiltration 

rates (deep percolation) for both present 

and future climatic conditions at Yucca 

Mountain encompass and exceed in 

sophistication the methods discussed in 

NUREG/CR–6565. The technical 

methods used by the NRC to account for 

uncertainty are discussed in detail 

under Issue 5 (What is the range of 

estimated present-day deep percolation 

rates and the appropriate range of future 

deep percolation rates?). 

The guidance in NUREG/CR–6565 

applies to SDMP sites and recommends 

an appropriate level of modeling 

sophistication commensurate with the 

risk of such sites. This is consistent with 

NRC’s general approach of using simple 

models for simple sites with low 

likelihood of exceeding exposure 

criteria, and using increasingly 

sophisticated models and requiring 

more robust data for more complex sites 

that pose potentially greater risks to 

public safety. The more detailed 


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requirements in Part 63 and the 

associated guidance in the YMRP are 

appropriate for the site complexity of 

Yucca Mountain and for the greater risk 

associated with HLW disposal. 

For example, NUREG/CR–6565 

recommends the use of generic models, 

such as Residual Radiation (RESRAD) 

and Multimedia Environmental 

Pollutant Assessment System (MEPAS), 

which simplify the physical system to 

reduce computational effort. 

Conversely, a site-specific performance 

assessment model with all the processes 

considered important at Yucca 

Mountain is needed to determine if Part 

63 performance objectives are met. Both 

generic models and site-specific models 

are typically run in Monte Carlo mode 

to address uncertainty. In addition, 

NUREG/CR–6565 provides tables of 

generic hydraulic parameter 

distributions to use in lieu of sitespecific parameters that are not 

typically available for SDMP sites, 

whereas the YMRP provides technical 

acceptance criteria for data sufficiency 

and uncertainty specific to Yucca 

Mountain. 

Issue 7: To what degree does the 

stylized climate scenario depend on 

information provided by the USGS? 

Comment. One commenter indicated 

NRC’s proposal is unsupportable 

because it is based on the past work of 

USGS personnel that is the subject of 

continuing criminal and civil 

investigation because of the apparent 

falsification of infiltration data and 

associated quality assurance records. 

Response. The stylized climate 

scenario and deep percolation rate in 

the final rule do not depend only on 

information provided by the USGS. The 

NRC has developed its own model and 

has performed independent field 

observations and measurements to 

support this final rule. In addition, the 

NRC has evaluated other regional 

information to corroborate its estimates 

of percolation under different climate 

regimes (Stothoff and Musgrove, 

‘‘Literature Review and Analysis: 

Climate and Infiltration,’’ San Antonio, 

TX: Center for Nuclear Waste Regulatory 

Analyses, 2006). 

To address uncertainty in estimates of 

net infiltration (and hence, deep 

percolation) during future climates, 

NRC developed its own independent 

climate and net infiltration models. 

Some DOE information that NRC judged 

to be reasonable from a scientific 

perspective was used in the model 

inputs. Further, NRC understands that 

DOE has reaffirmed the quality of data 

used in response to the USGS e-mail 

issue investigations. For important 

model inputs, NRC independently 

collected data to gain confidence in the 

model results. 

Three of the most important model 

inputs are precipitation, soil thickness, 

and incident solar energy. For 

precipitation, NRC analyzed local and 

regional data patterns and developed a 

future climate model based on ice core 

volumes (Stothoff and Walter, ‘‘LongTerm Average Infiltration at Yucca 

Mountain, Nevada: Million-Year 

Estimates,’’ San Antonio, TX: Center for 

Nuclear Waste Regulatory Analyses, 

2007). NRC climate model results were 

compared with indirect observations 

such as lake records and glacier 

advances in the Sierra Mountains. For 

soil thickness, NRC made its own 

measurements at the ridges and 

hillslopes of Yucca Mountain (Fedors, 

‘‘Soil Depths Measured at Yucca 

Mountain During Site Visits in 1998,’’ 

Interoffice Note to J. Guttmann, 

Washington, DC: Nuclear Regulatory 

Commission, January 9, 2007). NRC 

used the measurements of soil depth to 

gain confidence in its own model for 

soil thickness across the Yucca 

Mountain area. For the incident solar 

energy, which is important for 

evaporation in this semi-arid climate, 

NRC independently developed its own 

energy model from the general literature 

(Stothoff, ‘‘BREATH Version 1.1— 

Coupled Flow and Energy Transport in 

Porous Media: Simulator Description 

and User Guide,’’ Washington, DC: 

Nuclear Regulatory Commission, 1995). 

Previously, NRC had developed a 

bulk bedrock permeability model 

(Waiting, et al. ‘‘Technical Assessment 

of Structural Deformation and 

Seismicity at Yucca Mountain, Nevada,’’ 

San Antonio, TX: Center for Nuclear 

Waste Regulatory Analyses, 2001) and 

performed independent soil 

permeability measurements, which 

provided a basis to evaluate the 

reasonableness of related DOE data 

‘‘Infiltration Tabulator for Yucca 

Mountain: Bases and Confimation,’’ San 

Antonio, TX: Center for Nuclear Waste 

Regulatory Analyses, August, 2008; and 

Fedors (Soil Hydraulic Properties 

Measured During Site Visits to Yucca 

Mountain, Nevada,’’ Interoffice Note to 

E. Peters, Washington, DC: Nuclear 

Regulatory Commission, August, 2008). 

NRC’s model for estimating net 

infiltration is independent of the DOE 

model and uses a different 

conceptualization. The NRC model is a 

physically-based numerical heat and 

mass transfer model, which solves the 

Richards equation for water flow, with 

hourly climatic inputs to determine net 

infiltration for a range of climates and 

hydraulic property sets. Results from 

the heat and mass transfer model are 

used to develop an abstraction that is 

applied to Geographical Information 

System (GIS) based inputs covering the 

Yucca Mountain area. In addition, a 

surface water flow model based on the 

kinematic wave equation and linked to 

a two-layer infiltration algorithm is used 

to develop abstracted results to account 

for the effect of runoff and runon. The 

DOE model, on the other hand, is based 

on a water balance or ‘‘bucket,’’ 

approach. The DOE model is applied 

within a GIS framework and includes 

surface water routing. 

Irrespective of the USGS matter, NRC 

is confident its model for estimating net 

infiltration is reasonable, because NRC 

has developed its model independent of 

DOE and DOE’s contractors, NRC 

performed independent field 

observations and measurements, and 

NRC evaluated other regional 

information to corroborate its estimates 

of deep percolation rates under different 

climate regimes. 

Issue 8: Does NRC’s specification of a 

particular value for deep percolation at 

this time limit the consideration of 

future scientific information for 

changing the specified value? 

Comment. One commenter stated that 

the specification of an infiltration rate 

years before DOE’s license application is 

even filed is premature and unwise 

given the potential for new models for 

infiltration, which will likely have 

enhanced spatial and temporal 

resolution. Another commenter stated 

that if DOE’s climatic analysis and 

forecast differ from the deep percolation 

rates set in the amended rule, then 

NRC’s specification for deep percolation 

should serve as a point of reference in 

NRC’s license review proceedings. NRC 

license reviewers should be open to the 

possibility that other analytical methods 

may exist for addressing future climate 

changes for such long periods. New 

models for climate change may include 

consideration of potential future 

anthropogenic influences on Yucca 

Mountain. 

Response. The Commission disagrees 

with the commenters. The NRC 

recognizes that scientific progress is 

expected to continue the understanding 

of potential future climate. However, the 

intention of the rule is to specify a 

reasonable basis for evaluating safety 

using current knowledge. Given the 

current approach for estimating deep 

percolation, it would take a major shift 

in scientific understanding for the deep 

percolation rates to change significantly. 

For example, if future scientific 

advances suggest there is a period when 

there would be no rainfall in the Yucca 

Mountain area for a period of 100,000 

years, this would result in a ten percent 


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10824 Federal Register / Vol. 74, No. 48 / Friday, March 13, 2009 / Rules and Regulations 

change in the long-term average over the 

1-million-year period. Such changes are 

not expected to significantly change 

dose estimates. However, if future 

scientific advances show the regulation 

is no longer sufficiently protective of 

public health and safety and the 

environment, NRC would not hesitate to 

propose appropriate changes to the 

regulations. 

Further, if any person believes that 

the specification for climate change no 

longer provides a reasonable basis for 

demonstrating compliance based on 

new scientific evidence, they can 

petition NRC to amend the rules. In 

addition, NRC’s procedural rules enable 

any party to an adjudicatory proceeding 

to petition that application of a rule be 

waived in circumstances when the rule 

would not serve the purposes for which 

it was adopted [See also response to 

Issue 3 under NRC Adoption of EPA 

Standards and Response to Issue 7 

under Clarification of NRC’s 

Implementation of FEPs for the 

Performance Assessment for the Period 

after 10,000 Years of this document]. 

Issue 9: Does NRC’s analytical basis 

for its specification of a deep 

percolation rate comply with the 

Information Quality Act (IQA) and the 

associated Office of Management and 

Budget (OMB) guidelines? 

Comment. The State of Nevada stated 

that NRC’s calculations and judgments 

did not undergo scientific peer review, 

contrary to the IQA and OMB 

guidelines. The State asserted that NRC 

is overwhelmingly relying on EPA 

information and indirectly on EPA’s 

contractor documents cited in the 

proposed standards. 

Response. NRC considers its 

calculations and technical bases 

supporting the deep percolation 

estimates to be consistent with the IQA 

and the associated OMB guidelines 

concerning peer review. The OMB peer 

review guidance applies to ‘‘influential 

scientific information’’ that will have a 

clear and substantial impact on 

important public policies or the private 

sector (70 FR 2667; January 14, 2005). 

The distribution and range for deep 

percolation rates have a limited effect 

on repository performance and expected 

dose given the nature of the geologic 

environment and anticipated 

performance of engineered barriers (see 

response to Issue 3 under Climate 

Change of this document). Specifying 

deep percolation assumptions in NRC 

regulations limits unbounded 

speculation concerning a narrow and 

discrete aspect of the overall 

performance assessment. Doing so does 

not determine either how DOE will 

apply that range of rates over the entire 

repository horizon or DOE’s related 

analysis of the consequences for 

repository performance, much less 

constrain an NRC conclusion with 

respect to the acceptability of a potential 

application. Consequently, NRC does 

not consider its specification of the deep 

percolation rates or the data supporting 

it to be influential scientific information 

within the meaning of the OMB 

guidance. 

As discussed in relation to Climate 

Change issues 1 through 7 of this 

document, NRC’s estimates of deep 

percolation are appropriate and wellsupported. Based on public comment, 

the NRC has revised its specification for 

deep percolation values and provided 

additional clarification for the basis of 

the range of values (see Climate Change 

responses in this document). Further, 

these values are independent of any 

work or information provided by EPA or 

its contractors. With respect to the basis 

for the deep percolation rates, the NRC 

is not, as asserted by the State of 

Nevada, ‘‘overwhelmingly relying on 

EPA information, including EPA’s 

contractor documents’’ in its 

calculations and judgments when the 

responsibility rests with NRC. 

4. Use of Current Dosimetry 

Issue 1: Is the specification for using 

current methods of dosimetry and 

updated models for calculating potential 

radiation exposures sufficiently clear? 

Comment. DOE commented that the 

proposed approach for using current 

methods for dosimetry and updated 

models for dose calculations should be 

clarified in two specific areas. First, the 

definition for ‘‘weighting factor’’ in the 

proposed regulation refers only to the 

tissue weighting factors provided in 

Appendix A of EPA’s proposed 

standards and does not directly identify 

the radiation weighting factors also 

included in Appendix A. This 

definition should be expanded to 

include the radiation weighting factors 

specified in EPA’s proposed standards. 

Second, Federal Guidance Report 13 is 

the current guidance report for 

estimating radiation doses; however, 

this report considers a slightly different 

set of organs than those included by 

EPA in Table A.2 (70 FR 49063), which 

represents the most current 

recommendations from the International 

Commission on Radiological Protection 

(ICRP). Clarification is needed on using 

current dosimetry methods because of 

the potential for differences in the list 

of organs considered in a particular 

method. Additionally, DOE suggested 

that one potential solution was for NRC 

to simply require that the calculation of 

doses be consistent with ICRP 60/72 

methodology, use current scientific 

methods, and not provide any specific 

values in the regulation. 

Response. The definition for 

‘‘weighting factor’’ for an organ or tissue 

in the proposed regulation states that 

‘‘the values’’ in Appendix A of 40 CFR 

Part 197 are to be used for calculating 

the effective dose equivalent. This 

statement was intended to indicate that 

all the values in Appendix A (weighting 

factors for both radiation and for an 

organ or tissue) are to be used for 

calculating the effective dose 

equivalent. The Commission no longer 

considers it necessary to add a 

definition of the weighting factor in 

order to implement the values in 

Appendix A. Instead, the Commission 

clarifies the ‘‘implementation’’ of total 

effective dose equivalent (TEDE), 

specifically, the manner in which the 

values in Appendix A are to be used in 

dose calculations. The new text on the 

implementation of TEDE now states that 

the radiation and organ or tissue 

weighting factors in Appendix A are to 

be used in calculating the effective dose 

equivalent. Implementation of TEDE 

appears in the concepts section of 

Subpart E (Technical Criteria) in Part 

63. Based on the added text on 

implementation of TEDE, the proposed 

definition for weighting factor is no 

longer necessary and has been removed 

in the final regulation. 

The Commission is aware that as 

dosimetry methods have advanced, 

additional organs have been considered 

in determining weighting factors and 

thus, there are differences in the lists of 

organs used in specific methods for 

estimating dose. The intent of the 

standards and regulations is to provide 

an approach for using currently 

accepted dosimetry methods and 

updated models for estimating radiation 

exposures and not for fixing a list of 

organs or tissues. The Commission 

considers currently accepted dosimetry 

methods to include those incorporated 

by EPA into federal radiation guidance 

as well as those included in 40 CFR Part 

197, Appendix A. The Commission 

recognizes that the information 

presently available from consensus 

scientific organizations on newer 

dosimetric models (e.g., tabulations of 

calculated dose coefficients) differ for 

internal dose estimation relative to 

external dose estimation. Given this 

circumstance, use of external dosimetry 

methods in existing federal radiation 

guidance, Federal Guidance Report No. 

12 (EPA, 1993), in combination with the 

more current internal dosimetry 

methods consistent with 40 CFR Part 

197, Appendix A, is an acceptable 

approach for calculating TEDE. 


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Federal Register / Vol. 74, No. 48 / Friday, March 13, 2009 / Rules and Regulations 10825 

Whatever dosimetry method is used to 

estimate dose, it is expected that the 

calculation will consider the list of 

organs or tissues appropriate to that 

specific method. One way to clarify this 

issue would be to adopt the DOE 

suggestion to merely require that the 

calculation of doses be consistent with 

ICRP 60/72 methodology and use 

current scientific methods, and not 

provide any specific values in the 

regulation. Appendix A of the EPA 

Standards (73 FR 61256; October 15, 

2008) allows NRC to permit DOE to use 

revised weighting factors as updates are 

made in the future when these factors 

have been issued by a consensus of 

scientific organizations and 

incorporated by EPA into Federal 

radiation guidance. Rather than adopt 

the DOE suggestion that includes a 

reference to a specific methodology, the 

Commission considers it more 

appropriate to add text on implementing 

TEDE to: 

(1) Clarify that whatever methodology 

is adopted the weighting factors used in 

the calculation of dose are to be 

appropriate to the specific method; 

(2) Continue to refer to the values 

provided in Appendix A of the 

standards as the values that are 

presently considered to be current and 

appropriate; and 

(3) Prescribe the basis how DOE may 

be allowed to use newer methods and 

models. 

Thus, the regulations provide a 

consistency between the requirements 

for dose calculations and the scientific 

models and methodologies for 

calculating dose as scientific knowledge 

improves. Additionally, NRC’s 

Regulatory Issue Summary 2003–04, 

‘‘Use of the Effective Dose Equivalent in 

Place of the Deep Dose Equivalent in 

Dose Assessments,’’ provides further 

information on this topic. 

The implementation of TEDE is 

applicable in the context of dose 

calculations performed to demonstrate 

compliance with the requirements for a 

potential repository at Yucca Mountain. 

Issue 2: Should the definition for 

TEDE include clarification regarding 

how operational doses to workers are to 

be calculated? 

Comment. DOE commented that the 

definition of TEDE should clarify that 

assessing (monitoring) external 

exposure to workers during operations 

should use the deep-dose equivalent, 

whereas, potential external doses to 

workers in the future should be 

calculated using an effective dose 

equivalent. This clarification is 

necessary to resolve potential 

inconsistencies in the application of 

dose calculations between Parts 20 (i.e., 

monitored doses) and 63 (calculated 

doses). 

Response. Clarification regarding the 

monitoring of doses versus calculation 

of doses is essentially an issue of 

implementation of TEDE and is not one 

of redefining the term itself. Therefore, 

NRC is adding a separate discussion 

regarding implementation of TEDE in 

the concepts section of Subpart E 

(Technical Criteria) in Part 63 to provide 

the necessary clarification rather than 

modifying the definition of TEDE. The 

NRC is also revising the definition for 

TEDE in Part 63 to be consistent with 

the definition for TEDE in Part 20 to 

further clarify this is an issue of 

implementation of TEDE and not the 

definition of TEDE. 

As correctly stated in the comment, 

the deep-dose equivalent is an approach 

used for measuring external doses in the 

field, as is often done for demonstrating 

compliance with occupational 

exposures. The new text on 

implementation of TEDE clarifies that: 

(1) When the external exposure is 

determined by measurement with an 

external personal monitoring device, the 

deep dose equivalent is to be used 

instead of the effective dose equivalent, 

unless the effective dose equivalent is 

determined by a dosimetry method 

approved by the NRC; 

(2) The assigned deep-dose equivalent 

must be for the part of the body 

receiving the highest exposure; and 

(3) The assigned shallow-dose 

equivalent must be the dose averaged 

over the contiguous 10 square 

centimeters of skin receiving the highest 

exposure. 

The added text on implementation of 

TEDE provides the necessary 

clarification on how the deep-dose 

equivalent is to be used in determining 

compliance with the regulations for 

Yucca Mountain. Additionally, NRC’s 

Regulatory Issue Summary 2003–04, 

‘‘Use of the Effective Dose Equivalent in 

Place of the Deep Dose Equivalent in 

Dose Assessments,’’ provides further 

information on this topic. 

5. Comments Beyond the Scope of This 

Rulemaking 

Some commenters submitted 

comments which are beyond the scope 

of this rulemaking as described in NRC’s 

notice of proposed rulemaking. NRC 

responds to some of the concerns raised 

below. In addition, the State of Nevada 

requested that comments viewed as 

being beyond the scope of the 

rulemaking be considered as a petition 

for rulemaking. The State is familiar 

with NRC’s process for considering 

petitions for rulemaking which is 

initiated by submittal of a petition 

under 10 CFR 2.802 which meets the 

criteria of 10 CFR 2.802(c). 

Issue 1: Were intergovernmental 

meetings concerning the proposed EPA 

standards inappropriate? 

Comment. The State of Nevada and 

some other commenters suggested that 

non-public intergovernmental meetings 

at which EPA’s proposed standards 

were discussed were somehow 

inappropriate and cast a cloud on EPA 

and NRC rules. These commenters cite 

no laws nor regulations barring such 

discussions but nevertheless assume 

that such meetings should not have 

taken place. 

Response. In the Nuclear Waste Policy 

Act of 1982, as amended (NWPA), 

Congress recognized the responsibility 

of the Federal Government to provide 

for the permanent disposal of HLW and 

spent nuclear fuel in order to protect 

public health and safety and the 

environment. Congress, in the NWPA 

and later in the EnPA, charged EPA and 

NRC with specific direction for 

developing standards and regulations 

for Yucca Mountain: EPA is to provide 

public health and radiation protection 

standards; NRC is to provide 

implementing regulations for those 

standards and is to consider a license 

application from DOE for the 

construction, operation, and closure of 

the repository at a site DOE has found 

suitable. It makes little sense for these 

agencies to act oblivious to the views of 

each other as to how protection of 

public health and safety and the 

environment with respect to a geologic 

repository can best be accomplished. It 

is both appropriate and important for 

NRC to be able to explain and discuss 

its regulatory approach in the context of 

the EPA standard with other Federal 

agencies. The State, in fact, recognizes 

this. In its comments, the State urged 

NRC to ‘‘convince EPA to adopt a more 

reasonable and protective standard.’’ 

Although intergovernmental meetings 

are not normally open to the public, 

what is important is the fact that no 

‘‘secret’’ decisions resulted from 

interagency discussions. Both the EPA’s 

proposed standards and NRC’s proposed 

regulations, including their rationale, 

were provided to the public for 

comment. After careful consideration of 

the public comments, both EPA and 

NRC have explained and documented 

their final standards and regulations, 

including how public comments were 

taken into account. The standards and 

regulations will stand or fall on the 

basis of the public record on which they 

rest, not on the basis of any discussions 

that may have taken place while the 

standards were being formulated. 


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Issue 2: Should NRC provide 

additional requirements for defense-indepth? 

Comment. The State of Nevada 

believes that a meaningful defense-indepth standard is missing from the NRC 

rule. The State also suggested that a 

requirement pertaining to the expected 

performance of natural barriers would 

offer an essential protective feature for 

coping with early waste package failure 

(noting that the International Atomic 

Energy Agency (IAEA) has suggested 

that ‘‘overall performance of the 

geologic disposal system shall not be 

unduly dependent on a single barrier or 

function’’). 

Response. The Commission considers 

the approach for multiple barriers and 

defense-in-depth in Part 63 appropriate 

and protective. When NRC issued final 

Part 63 on November 2, 2001 (66 FR 

55758), the Commission stated the goal 

of the current regulations regarding 

multiple barriers and defense-in-depth 

and explained its reasoning for not 

specifying requirements for specific 

barriers: 

The emphasis should not be on the isolated 

performance of individual barriers but rather 

on ensuring the repository system is robust, 

and is not wholly dependent on a single 

barrier. Further, the Commission supports an 

approach that would allow DOE to use its 

available resources effectively to achieve the 

safest repository without unnecessary 

constraints imposed by separate, additional 

subsystem performance requirements. 

It is also important to remember that part 

63 requires DOE to carry out a performance 

confirmation program to provide further 

confidence that barriers important to waste 

isolation will continue to perform as 

expected (66 FR 55758). 

The court addressed this same issue in 

Nevada’s suit challenging the Part 63 

rule: 

Specifically, Nevada contests NRC’s use of 

defense-in-depth at the proposed Yucca 

Mountain repository through an overall 

system performance assessment rather than 

using the approach of its older regulations, 

which approach tests the individual 

performance of the repository’s ‘system 

elements.’ * * * In light of NRC’s detailed 

analysis supporting its decision to evaluate 

the performance of the Yucca Mountain 

repository based on the barrier system’s 

overall performance, we believe that it 

adequately explained its change in course. 

* * * Accordingly, we conclude that NRC 

acted neither arbitrarily nor capriciously in 

rejecting part 60’s subsystem performance 

approach in favor of the overall performance 

approach. NEI v. EPA; 373 F.3d 1251, 1295– 

97 

(DC Cir. 2004). 

Issue 3: Should NRC disabuse EPA of 

its mistaken impression that there is 

some significant difference between 

‘‘reasonable assurance’’ and ‘‘reasonable 

expectation?’’ 

Comment. The State of Nevada 

asserted that NRC must disabuse EPA of 

its mistaken impression that there is 

some significant difference between the 

term ‘‘reasonable assurance’’ and the 

term ‘‘reasonable expectation.’’ 

Response. As noted by the State, NRC 

and the State have already agreed that 

the two terms are substantially 

identical, see NEI v. EPA; 373 F.3d 

1251, 1301 (D.C. Cir. 2004). 

Issue 4: Should NRC prohibit DOE 

from relying on drip shields that may be 

installed in the distant future (e.g., 300 

years from now)? 

Comment. The State of Nevada 

expressed concern that drip shields 

could be scheduled for installation 

many years in the future and, thus, there 

is no real guarantee that this safety 

feature will actually be installed. There 

is no reliable way to commit future 

decision-makers on this point. 

Therefore, NRC should not allow DOE 

to rely on the drip shields in 

demonstrating compliance with the 

post-closure performance objectives. 

Response. DOE must apply to NRC for 

authorization to build the proposed 

repository. Under NRC’s regulations, 

DOE must show, among other things, 

that its proposal will comply with 

specified performance objectives for the 

geologic repository after permanent 

closure. On June 3, 2008, DOE 

submitted a license application to NRC 

for authorization to construct a 

repository at Yucca Mountain. The NRC 

staff will evaluate whether DOE’s 

proposed design, including reliance on 

any specific design feature or 

component of the engineered barrier 

system as described in the application, 

succeeds in making the required 

demonstration. 

The NRC staff will then document its 

assessment in a Safety Evaluation 

Report. If the NRC staff recommends 

that NRC authorize construction, the 

staff may specify potential license 

conditions, as needed, to provide 

reasonable expectation that relevant 

performance objectives will be met. 

NRC can only assess the need for such 

conditions, their reasonableness, and 

their potential to be enforced in the 

context of DOE’s overall design as 

presented in a license application. If 

DOE proposes to install drip shields and 

if the drip shields are considered 

important for waste isolation or 

repository performance, the installation 

of the drip shield at an appropriate time 

would become part of the license 

conditions. At a later date, if DOE 

proposes not to install the drip shields, 

DOE would be obligated to seek specific 

regulatory approval in the form of a 

license amendment. Any NRC decision 

to grant or deny such an amendment 

request would be based on NRC’s 

independent technical review and 

would be subject to a potential hearing 

as part of the amendment process. 

Issue 5: Should NRC incorporate into 

the final rule requirements for 

compliance monitoring and measures to 

be taken in the event of noncompliance? 

Comment. Some commenters pointed 

out that NRC’s proposed rule appears to 

be silent with regard to requirements for 

compliance monitoring and related 

measures to be taken if said monitoring 

demonstrates noncompliance with 

established standards. The commenters 

encouraged NRC to incorporate such 

requirements into the final rule. 

Response. Part 63 contains 

requirements for monitoring up to the 

time of permanent closure in Subpart F. 

Should the NRC grant the DOE a license 

to operate the repository, DOE must also 

provide a description of its program for 

post-permanent closure monitoring in 

its application to amend its license for 

permanent closure. See, § 63.51(a)(2). 

The commenters’ concerns regarding 

further monitoring and related measures 

can be considered at that time. 

Issue 6: Will adoption of the EPA 

standards necessitate revision of the 

‘‘S–3’’ rule? 

Comment. The State of Nevada 

believes that NRC’s adoption of EPA’s 

standards with no added protections 

will require NRC to revisit its ‘‘S–3’’ 

rule, 10 CFR 51.51, because this rule 

currently includes a ‘‘zero-release’’ 

assumption that the long-term effects of 

disposing of spent fuel and HLW will be 

essentially zero because there would be 

no releases that would harm people or 

the environment after the repository is 

sealed. The State believes that this will 

no longer be the case if NRC adopts 

EPA’s 3.5 mSv (350 mrem) standard for 

the post-10,000 year period. 

Response. As explained in the 

response to the comment on Issue 1 

under NRC Adoption of EPA Standards 

of this document, EnPA requires the 

Commission to modify its technical 

criteria to be consistent with EPA’s 

standards for a geologic repository at the 

Yucca Mountain site. Moreover, the 

question whether the ‘‘zero-release’’ 

assumption of the S–3 rule may need to 

be revisited in the future is not 

presented in this rulemaking 

proceeding. 


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IV. Summary of Final Revisions 

Section 63.2 Definitions 

The definition of ‘‘performance 

assessment’’ is revised to exclude the 

limitation of ‘‘10,000 years after 

disposal,’’ consistent with EPA’s 

modified definition of ‘‘performance 

assessment.’’ The definition for ‘‘total 

effective dose equivalent’’ is revised to 

be consistent with Part 20. 

Section 63.102 Concepts 

A discussion of the implementation of 

total effective dose equivalent (TEDE) is 

added to the concepts section to clarify 

how the weighting factors specified in 

EPA’s final standards are to be used for 

calculating potential exposures. 

Section 63.114 Requirements for 

Performance Assessment 

This section specifies the 

requirements for the performance 

assessment used to demonstrate 

compliance with the postclosure 

performance objectives. This section is 

revised to conform to EPA’s final 

standards that specify what DOE must 

consider in the performance assessment 

for the period after 10,000 years i.e., the 

performance assessment methods 

meeting the existing requirements for 

the initial 10,000 years are appropriate 

and sufficient for the period after 10,000 

years. 

Section 63.302 Definitions for Subpart 

L 

The definition for the ‘‘period of 

geologic stability’’ is modified, 

consistent with EPA’s final standards, to 

clarify that this period ends at 1 million 

years after disposal. 

Section 63.303 Implementation of 

Subpart L 

This section provides a functional 

overview of this subpart. This section is 

revised to conform to EPA’s final 

standard that specifies for the period 

after 10,000 years, the arithmetic mean 

of the estimated doses is to be used for 

determining compliance. 

Section 63.305 Required 

Characteristics of the Reference 

Biosphere 

This section specifies characteristics 

of the reference biosphere to be used by 

DOE in its performance assessments to 

demonstrate compliance with the 

postclosure performance objectives 

specified at § 63.113. This section is 

modified to conform to EPA’s final 

standards, which specify the types of 

changes DOE must account for in the 

performance assessment for the period 

after 10,000 years and through the 

period of geologic stability. 

Section 63.311 Individual Protection 

Standard After Permanent Closure 

This section specifies the dose limit 

for individual protection after 

permanent closure for any geologic 

repository at the Yucca Mountain site. 

This section is modified to conform 

with EPA’s final standards for the peak 

dose after 10,000 years and through the 

period of geologic stability. 

Section 63.321 Individual Protection 

Standard for Human Intrusion 

This section directs DOE to estimate 

the dose resulting from a stylized 

human intrusion drilling scenario and 

specifies the dose limit that any geologic 

repository at the Yucca Mountain site 

must meet as the result of a hypothetical 

human intrusion. This section is 

modified to conform with EPA’s final 

standards for the peak dose after 10,000 

years and through the period of geologic 

stability. 

Section 63.341 Projections of Peak 

Dose 

This section has been removed to be 

consistent with EPA’s final standards. 

Section 63.342 Limits on Performance 

Assessments 

This section specifies how DOE will 

identify and consider features, events, 

and processes in the dose assessments 

described in Subpart L to Part 63. This 

section is modified to conform to EPA’s 

final standards that specify the types of 

changes DOE must account for in the 

performance assessment for the period 

after 10,000 years and through the 

period of geologic stability. A range and 

distribution for deep percolation rates 

are specified that DOE must use to 

represent the effects of climate change 

after 10,000 years and through the 

period of geologic stability. These 

criteria are substantially the same as 

those proposed by EPA and NRC with 

the exception of the constraint that 

requires DOE to consider, in its 

performance assessment, changes to the 

elevation of the water table under Yucca 

Mountain (i.e., water table rise) from a 

seismic event, which is included in the 

final regulations. 

V. Agreement State Compatibility 

Under the ‘‘Policy Statement on 

Adequacy and Compatibility of 

Agreement State Programs’’ approved by 

the Commission on June 30, 1997, and 

published in the Federal Register on 

September 3, 1997 (62 FR 46517), this 

rule is classified as Compatibility 

Category ‘‘NRC.’’ Compatibility is not 

required for Category ‘‘NRC’’ 

regulations. The NRC program elements 

in this category are those that relate 

directly to areas of regulation reserved 

to the NRC by the Atomic Energy Act of 

1954, as amended (AEA), or the 

provisions of Title 10 of the Code of 

Federal Regulations. 

VI. Voluntary Consensus Standards 

The National Technology Transfer 

and Advancement Act of 1995 (Pub. L. 

104–113) requires that Federal agencies 

use technical standards that are 

developed or adopted by voluntary 

consensus standards bodies unless the 

use of such a standard is inconsistent 

with applicable law or otherwise 

impractical. In this final rule, the NRC 

implements site-specific standards 

proposed by EPA and developed solely 

for application to a proposed geologic 

repository for high-level radioactive 

waste at Yucca Mountain, Nevada. This 

action does not constitute the 

establishment of a standard that sets 

generally applicable requirements. 

VII. Finding of No Significant 

Environmental Impact: Availability 

Under Section 121(c) of the Nuclear 

Waste Policy Act, this final rule does 

not require the preparation of an 

environmental impact statement under 

Section 102(2)(c) of the National 

Environmental Policy Act of 1969 

(NEPA) or any environmental review 

under paragraphs (E) or (F) of Section 

102(2) of NEPA. 

VIII. Paperwork Reduction Act 

Statement 

This final rule does not contain new 

or amended information collection 

requirements subject to the Paperwork 

Reduction Act of 1995 (44 U.S.C. 3501 

et seq.). Existing requirements were 

approved by OMB, approval number 

3150–0199. 

Public Protection Notification 

NRC may not conduct nor sponsor, 

and a person is not required to respond 

to, a request for information nor an 

information collection requirement, 

unless the requesting document 

displays a currently valid OMB control 

number. 

IX. Regulatory Analysis 

The Commission has prepared a 

regulatory analysis on this regulation. 

The analysis examines the costs and 

benefits of the alternatives considered 

by the Commission, consistent with the 

options that are available to NRC in 

carrying out the statutory directive of 

EnPA. The analysis is available for 

inspection in the NRC PDR, Room 


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O1F21, One White Flint North, 11555 

Rockville Pike, Rockville, MD. 

X. Regulatory Flexibility Certification 

Under the Regulatory Flexibility Act 

of 1980 (5 U.S.C. 605(b)), the 

Commission certifies that this rule does 

not have a significant economic impact 

on a substantial number of small 

entities. This rule affects the licensing of 

only one entity, DOE, which does not 

fall within the scope of the definition of 

‘‘small entities’’ set forth in the 

Regulatory Flexibility Act or the Small 

Business Size Standards set out in 

regulations issued by the Small 

Business Administration at 13 CFR Part 

121. 

XI. Backfit Analysis 

The NRC has determined that the 

backfit rule (§§ 50.109, 70.76, 72.62, or 

76.76) does not apply to this final rule 

because this amendment does not 

involve any provisions that would 

impose backfits as defined in the backfit 

rule. Therefore, a backfit analysis is not 

required. 

XII. Congressional Review Act 

Under the Congressional Review Act 

of 1996, the NRC has determined that 

this action is not a major rule and has 

verified this determination with the 

Office of Information and Regulatory 

Affairs of OMB. 

List of Subjects in 10 CFR Part 63 

Criminal penalties, High-level waste, 

Nuclear power plants and reactors, 

Reporting and recordkeeping 

requirements, Waste treatment and 

disposal. 

■ For the reasons set out in the 

preamble and under the authority of the 

Atomic Energy Act of 1954, as amended; 

the Energy Reorganization Act of 1974, 

as amended; the Nuclear Waste Policy 

Act of 1982, as amended; and 5 U.S.C. 

552 and 553; the NRC is adopting the 

following amendments to 10 CFR Part 

63. 

PART 63—DISPOSAL OF HIGH-LEVEL 

RADIOACTIVE WASTES IN A 

GEOLOGIC REPOSITORY AT YUCCA 

MOUNTAIN, NEVADA 

■ 1. The authority citation for part 63 

continues to read as follows: 

Authority: Secs. 51, 53, 62, 63, 65, 81, 161, 

182, 183, 68 Stat. 929, 930, 932, 933, 935, 

948, 953, 954, as amended (42 U.S.C. 2071, 

2073, 2092, 2093, 2095, 2111, 2201, 2232, 

2233); secs. 202, 206, 88 Stat. 1244, 1246 (42 

U.S.C. 5842, 5846); secs. 10 and 14, Pub. L. 

95–601, 92 Stat. 2951 (42 U.S.C. 2021a and 

5851); sec. 102, Pub. L. 91–190, 83 Stat. 853 

(42 U.S.C. 4332); secs. 114, 121, Pub. L. 97– 

425, 96 Stat. 2213g, 2238, as amended (42 

U.S.C. 10134, 10141); and Pub. L. 102–486, 

sec. 2902, 106 Stat. 3123 (42 U.S.C. 5851); 

sec. 1704, 112 Stat. 2750 (44 U.S.C. 3504 

note). 

■ 2. Section 63.2 is amended by revising 

paragraph (1) of the definition of 

‘‘performance assessment’’ and revising 

the definition of ‘‘total effective dose 

equivalent (TEDE)’’ to read as follows: 

§ 63.2 Definitions. 

* * * * * 

Performance assessment means an 

analysis that: (1) Identifies the features, 

events, processes (except human 

intrusion), and sequences of events and 

processes (except human intrusion) that 

might affect the Yucca Mountain 

disposal system and their probabilities 

of occurring; 

* * * * * 

Total effective dose equivalent (TEDE) 

means the sum of the effective dose 

equivalent (for external exposures) and 

the committed effective dose equivalent 

(for internal exposures). 

* * * * * 

■ 3. In § 63.102 paragraph (o) is added 

to read as follows: 

63.102 Concepts. 

* * * * * 

(o) Implementation of TEDE. When 

external exposure is determined by 

measurement with an external personal 

monitoring device, the deep-dose 

equivalent must be used in place of the 

effective dose equivalent, unless the 

effective dose equivalent is determined 

by a dosimetry method approved by the 

NRC. The assigned deep-dose 

equivalent must be for the part of the 

body receiving the highest exposure. 

The assigned shallow-dose equivalent 

must be the dose averaged over the 

contiguous 10 square centimeters of 

skin receiving the highest exposure. The 

radiation and organ or tissue weighting 

factors in Appendix A of 40 CFR part 

197 are to be used to calculate TEDE. 

After the effective date of this 

regulation, the Commission may allow 

DOE to use updated factors, which have 

been issued by consensus scientific 

organizations and incorporated by EPA 

into Federal radiation guidance. 

Additionally, as scientific models and 

methodologies for estimating doses are 

updated, DOE may use the most current 

and appropriate (e.g., those accepted by 

the International Commission on 

Radiological Protection) scientific 

models and methodologies to calculate 

the TEDE. The weighting factors used in 

the calculation of TEDE must be 

consistent with the methodology used to 

perform the calculation. 

■ 4. Section 63.114 is revised to read as 

follows: 

63.114 Requirements for performance 

assessment. 

(a) Any performance assessment used 

to demonstrate compliance with 

§ 63.113 for 10,000 years after disposal 

must: 

(1) Include data related to the geology, 

hydrology, and geochemistry (including 

disruptive processes and events) of the 

Yucca Mountain site, and the 

surrounding region to the extent 

necessary, and information on the 

design of the engineered barrier system 

used to define, for 10,000 years after 

disposal, parameters and conceptual 

models used in the assessment. 

(2) Account for uncertainties and 

variabilities in parameter values, for 

10,000 years after disposal, and provide 

for the technical basis for parameter 

ranges, probability distributions, or 

bounding values used in the 

performance assessment. 

(3) Consider alternative conceptual 

models of features and processes, for 

10,000 years after disposal, that are 

consistent with available data and 

current scientific understanding and 

evaluate the effects that alternative 

conceptual models have on the 

performance of the geologic repository. 

(4) Consider only features, events, and 

processes consistent with the limits on 

performance assessment specified at 

§ 63.342. 

(5) Provide the technical basis for 

either inclusion or exclusion of specific 

features, events, and processes in the 

performance assessment. Specific 

features, events, and processes must be 

evaluated in detail if the magnitude and 

time of the resulting radiological 

exposures to the reasonably maximally 

exposed individual, or radionuclide 

releases to the accessible environment, 

for 10,000 years after disposal, would be 

significantly changed by their omission. 

(6) Provide the technical basis for 

either inclusion or exclusion of 

degradation, deterioration, or alteration 

processes of engineered barriers in the 

performance assessment, including 

those processes that would adversely 

affect the performance of natural 

barriers. Degradation, deterioration, or 

alteration processes of engineered 

barriers must be evaluated in detail if 

the magnitude and time of the resulting 

radiological exposures to the reasonably 

maximally exposed individual, or 

radionuclide releases to the accessible 

environment, for 10,000 years after 

disposal, would be significantly 

changed by their omission. 

(7) Provide the technical basis for 

models used to represent the 10,000 


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years after disposal in the performance 

assessment, such as comparisons made 

with outputs of detailed process-level 

models and/or empirical observations 

(e.g., laboratory testing, field 

investigations, and natural analogs). 

(b) The performance assessment 

methods used to satisfy the 

requirements of paragraph (a) of this 

section are considered sufficient for the 

performance assessment for the period 

of time after 10,000 years and through 

the period of geologic stability. 

■ 5. In § 63.302, the definition of 

‘‘period of geologic stability’’ is revised 

to read as follows: 

63.302 Definitions for Subpart L. 

* * * * * 

Period of geologic stability means the 

time during which the variability of 

geologic characteristics and their future 

behavior in and around the Yucca 

Mountain site can be bounded, that is, 

they can be projected within a 

reasonable range of possibilities. This 

period is defined to end at 1 million 

years after disposal. 

* * * * * 

■ 6. Section 63.303 is revised to read as 

follows: 

63.303 Implementation of Subpart L. 

(a) Compliance is based upon the 

arithmetic mean of the projected doses 

from DOE’s performance assessments 

for the period within 1 million years 

after disposal, with: 

(1) Sections 63.311(a)(1) and 

63.311(a)(2); and 

(2) Sections 63.321(b)(1), 63.321(b)(2), 

and 63.331, if performance assessment 

is used to demonstrate compliance with 

either or both of these sections. 

■ 7. Section 63.305, paragraph (c) is 

revised to read as follows: 

63.305 Required characteristics of the 

reference biosphere. 

* * * * * 

(c) DOE must vary factors related to 

the geology, hydrology, and climate 

based upon cautious, but reasonable 

assumptions of the changes in these 

factors that could affect the Yucca 

Mountain disposal system during the 

period of geologic stability, consistent 

with the requirements for performance 

assessments specified at § 63.342. 

* * * * * 

■ 8. Section 63.311 is revised to read as 

follows: 

§ 63.311 Individual protection standard 

after permanent closure. 

(a) DOE must demonstrate, using 

performance assessment, that there is a 

reasonable expectation that the 

reasonably maximally exposed 

individual receives no more than the 

following annual dose from releases 

from the undisturbed Yucca Mountain 

disposal system: 

(1) 0.15 mSv (15 mrem) for 10,000 

years following disposal; and 

(2) 1.0 mSv (100 mrem) after 10,000 

years, but within the period of geologic 

stability. 

(b) DOE’s performance assessment 

must include all potential pathways of 

radionuclide transport and exposure. 

■ 9. Section 63.321 is revised to read as 

follows: 

§ 63.321 Individual protection standard for 

human intrusion. 

(a) DOE must determine the earliest 

time after disposal that the waste 

package would degrade sufficiently that 

a human intrusion (see § 63.322) could 

occur without recognition by the 

drillers. 

(b) DOE must demonstrate that there 

is a reasonable expectation that the 

reasonably maximally exposed 

individual receives, as a result of the 

human intrusion, no more than the 

following annual dose: 

(1) 0.15 mSv (15 mrem) for 10,000 

years following disposal; and 

(2) 1.0 mSv (100 mrem) after 10,000 

years, but within the period of geologic 

stability. 

(c) DOE’s analysis must include all 

potential environmental pathways of 

radionuclide transport and exposure, 

subject to the requirements of § 63.322. 

§ 63.341 [Removed] 

■ 10. Section 63.341 is removed. 

■ 11. Section 63.342 is revised to read 

as follows: 

§ 63.342 Limits on performance 

assessments. 

(a) DOE’s performance assessments 

conducted to show compliance with 

§§ 63.311(a)(1), 63.321(b)(1), and 63.331 

shall not include consideration of very 

unlikely features, events, or processes, 

i.e., those that are estimated to have less 

than one chance in 100,000,000 per year 

of occurring. In addition, DOE’s 

performance assessments need not 

evaluate the impacts resulting from any 

features, events, and processes or 

sequences of events and processes with 

a higher chance of occurring if the 

results of the performance assessments 

would not be changed significantly in 

the initial 10,000-year period after 

disposal. 

(b) For performance assessments 

conducted to show compliance with 

§§ 63.321(b)(1) and 63.331, DOE’s 

performance assessments shall exclude 

the unlikely features, events, and 

processes, or sequences of events and 

processes, i.e., those that are estimated 

to have less than one chance in 100,000 

per year of occurring and at least one 

chance in 100,000,000 per year of 

occurring. 

(c) For performance assessments 

conducted to show compliance with 

§§ 63.311(a)(2) and 63.321(b)(2), DOE’s 

performance assessments shall project 

the continued effects of the features, 

events, and processes included in 

paragraph (a) of this section beyond the 

10,000-year post-disposal period 

through the period of geologic stability. 

DOE must evaluate all of the features, 

events, or processes included in 

paragraph (a) of this section, and also: 

(1) DOE must assess the effects of 

seismic and igneous activity scenarios, 

subject to the probability limits in 

paragraph (a) of this section for very 

unlikely features, events, and processes, 

or sequences of events and processes. 

Performance assessments conducted to 

show compliance with § 63.321(b)(2) are 

also subject to the probability limits in 

paragraph (b) of this section for unlikely 

features, events, and processes, or 

sequences of events and processes. 

(i) The seismic analysis may be 

limited to the effects caused by damage 

to the drifts in the repository, failure of 

the waste packages, and changes in the 

elevation of the water table under Yucca 

Mountain (i.e., the magnitude of the 

water table rise under Yucca Mountain). 

(ii) The igneous activity analysis may 

be limited to the effects of a volcanic 

event directly intersecting the 

repository. The igneous event may be 

limited to that causing damage to the 

waste packages directly, causing 

releases of radionuclides to the 

biosphere, atmosphere, or ground water. 

(2) DOE must assess the effects of 

climate change. The climate change 

analysis may be limited to the effects of 

increased water flow through the 

repository as a result of climate change, 

and the resulting transport and release 

of radionuclides to the accessible 

environment. The nature and degree of 

climate change may be represented by 

constant-in-time climate conditions. 

The analysis may commence at 10,000 

years after disposal and shall extend 

through the period of geologic stability. 

The constant-in-time values to be used 

to represent climate change are to be the 

spatial average of the deep percolation 

rate within the area bounded by the 

repository footprint. The constant-intime deep percolation rates to be used 

to represent climate change shall be 

based on a lognormal distribution with 

an arithmetic mean of 41 mm/year (1.6 

in./year) and a standard deviation of 33 

mm/year (1.3 in./year). The lognormal 


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distribution is to be truncated so that 

the deep percolation rates vary between 

10 and 100 mm/year (0.39 and 3.9 in./ 

year). 

(3) DOE must assess the effects of 

general corrosion on engineered 

barriers. DOE may use a constant 

representative corrosion rate throughout 

the period of geologic stability or a 

distribution of corrosion rates correlated 

to other repository parameters. 

Dated at Rockville, Maryland, this 9th day 

of March 2009. 

For the Nuclear Regulatory Commission. 

Annette L. Vietti-Cook, 

Secretary of the Commission. 

[FR Doc. E9–5448 Filed 3–12–09; 8:45 am] 

BILLING CODE 7590–01–P 

DEPARTMENT OF ENERGY 

10 CFR Part 436 

RIN 1904–AB68 

Federal Procurement of Energy 

Efficient Products 

AGENCY: Office of Energy Efficiency and 

Renewable Energy, Department of 

Energy. 

ACTION: Final rule. 

SUMMARY: The U.S. Department of 

Energy (DOE) today publishes a final 

rule to promote Federal procurement of 

energy-efficient products. The final rule 

establishes guidelines for Federal 

agencies regarding the implementation 

of amendments to the National Energy 

Conservation Policy Act (NECPA) that 

require Federal agencies to procure 

ENERGY STAR qualified and Federal 

Energy Management Program (FEMP) 

designated products in procurements 

involving energy consuming products 

and systems. Today’s final rule includes 

changes in response to comments 

received on the notice of proposed 

rulemaking published June 19, 2007. 

Most notably, today’s final rule does not 

establish a reporting requirement, as 

initially proposed, for federal agencies 

under procurement requirement of 

NECPA. 

DATES: This rule is effective April 13, 

2009. 

FOR FURTHER INFORMATION CONTACT: For 

technical issues contact Mr. Cyrus 

Nasseri, U.S. Department of Energy, 

Office of Energy Efficiency and 

Renewable Energy, Federal Energy 

Management Program, EE–2L, 1000 

Independence Avenue, SW., 

Washington, DC 20585–0121, (202) 586– 

9138, e-mail: cyrus.nasseri@ee.doe.gov. 

For legal issues contact Mr. Chris 

Calamita, U.S. Department of Energy, 

Office of the General Counsel, Forrestal 

Building, GC–72, 1000 Independence 

Avenue, SW., Washington, DC 20585, 

(202) 586–9507, e-mail: 

Christopher.Calamita@hq.doe.gov. 

SUPPLEMENTARY INFORMATION: 

I. Introduction and Background 

A. The Energy Policy Act of 2005 

B. ENERGY STAR Qualified and FEMP 

Designated Products 

C. Proposed Rule 

D. Draft Guidance 

II. Discussion of Comments and the Final 

Rule 

A. Definition of ‘‘Covered Product’’ 

B. Reporting Agency Exceptions to the 

Procurement Requirement 

C. Compliance With Section 553 

D. Definition of Criteria for ENERGY STAR 

Qualification or FEMP Designation 

E. Supply Source for Excepted 

Procurement 

III. DOE Guidance 

A. Procurements 

B. Procurement Planning 

C. Exceptions 

IV. Regulatory Review 

A. National Environmental Policy Act 

B. Regulatory Flexibility Act 

C. Paperwork Reduction Act 

D. Unfunded Mandates Reform Act of 1995 

E. Treasury and General Government 

Appropriations Act, 1999 

F. Treasury and General Government 

Appropriations Act, 2001 

G. Executive Order 12866 

H. Executive Order 12988 

I. Executive Order 13132 

J. Executive Order 13211 

V. Congressional Notification 

VI. Approval of the Office of the Secretary 

I. Introduction and Background 

A. The Energy Policy Act of 2005 

The Energy Policy Act of 2005 

(EPACT 2005) (Pub. L. 109–58; August 

8, 2005), amended Part 3 of title V of 

NECPA (42 U.S.C. 8251–8259) by 

adding section 553. Section 553 of 

NECPA requires each Federal agency to 

procure ENERGY STAR qualified or 

FEMP designated products, unless the 

head of the agency determines in 

writing that a statutory exception 

applies. (42 U.S.C. 8259b(b)) Section 

553 of NECPA was further amended by 

section 525 of the Energy Independence 

and Security Act of 2007 (Pub. L. 140– 

110; December 19, 2007) to clarify that 

the procurement requirement applies to 

the procurement of a product in a 

category covered by the Energy Star 

program or the FEMP program for 

designated products. (42 U.S.C. 

8259b(b)(1)) Further, each Federal 

agency is required to incorporate into 

the specifications of all procurements 

involving energy consuming products 

and systems, and into the factors for 

evaluation of offers received for such 

procurements, criteria for energy 

efficiency that are consistent with the 

criteria used for rating ENERGY STAR 

qualified products and for rating FEMP 

designated products. (42 U.S.C. 

8259b(b)(3)) 

Section 553 also requires that all 

inventories or listings of products 

operated and maintained by the General 

Services Administration (GSA) and the 

Defense Logistics Agency (DLA) clearly 

identify and prominently display 

ENERGY STAR qualified and FEMP 

designated products in any listing or 

inventory of products, and it requires 

GSA and DLA to supply only ENERGY 

STAR qualified and FEMP designated 

products in all covered product 

categories, except in cases in which the 

head of the agency ordering a product 

specifies in writing that an exception 

applies. (42 U.S.C. 8259b(c)) 

Section 553 of NECPA contains two 

exceptions to the requirement to 

procure only ENERGY STAR qualified 

and FEMP designated products, and it 

excludes a specific category of energy 

consuming products from coverage. 

A procurement may be excepted if the 

head of an agency finds in writing that 

either: (1) An ENERGY STAR qualified 

product or FEMP designated product is 

not cost-effective over the life of the 

product taking energy cost savings into 

account; or (2) no ENERGY STAR 

qualified product or FEMP designated 

product is reasonably available that 

meets the functional requirements of the 

agency. (42 U.S.C. 8259b(b)(2)) In 

addition, section 553 excludes from the 

definition of products subject to these 

requirements any energy consuming 

product or system designed or procured 

for combat or combat-related missions. 

(42 U.S.C. 8259b(a)(5)) 

The subsection entitled 

‘‘REGULATIONS,’’ section 553(f) of 

NECPA, directs the Secretary of Energy 

to issue guidelines to carry out the 

statute. (42 U.S.C. 8259b(f)) NECPA 

section 553 imposes procurement 

requirements on agencies and additional 

requirements on GSA and DLA. DOE 

does not need to issue regulations to 

implement those statutory requirements. 

Moreover, DOE does not have the 

authority to change by regulation the 

statutory procurement requirements that 

are applicable to agencies or the 

additional requirements that govern 

GSA and DLA. 

Consistent with the direction 

provided in section 553(f), today’s final 

rule amends 10 CFR part 436, Federal 

Energy Management and Planning 

Programs, to establish guidelines for 

Federal agencies on compliance with 

section 553. 


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