Disposal of High-Level Radioactive Wastes in Geologic Repositories; Design Basis Events

NUCLEAR REGULATORY COMMISSION

10 CFR Part 60

RIN 3150-AD51

Disposal of High-Level Radioactive Wastes in Geologic

Repositories; Design Basis Events

AGENCY: Nuclear Regulatory Commission.

ACTION: Final rule.

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SUMMARY: The Nuclear Regulatory Commission is amending its regulations

on the protection of public health and safety from activities conducted

at a geologic repository operations area (GROA) before permanent

closure. In particular, the final rule addresses the measures that are

required to provide defense in depth against the consequences of

``design basis events.'' These measures include prescribed design

requirements, quality assurance requirements, and the establishment of

a preclosure controlled area from which members of the public can be

excluded.

EFFECTIVE DATE: January 3, 1997.

FOR FURTHER INFORMATION, CONTACT: Dr. Richard A. Weller, Division of

Waste Management, Office of Nuclear Material Safety and Safeguards,

U.S. Nuclear Regulatory Commission, Washington, DC 20555, telephone

(301) 415-7287.

SUPPLEMENTARY INFORMATION:

Background

Under the Nuclear Waste Policy Act of 1982, as amended, the U.S.

Nuclear

[[Page 64258]]

Regulatory Commission exercises licensing and related regulatory

authority with respect to geologic repositories that are to be

constructed and operated by the U.S. Department of Energy (DOE) for the

disposal of high-level radioactive waste. The Commission's regulations

pertaining to these geologic repositories appear at 10 CFR part 60. In

recent years, NRC, in conjunction with its Federally-Funded Research

and Development Center, the Center for Nuclear Waste Regulatory

Analyses, completed a comprehensive review of the requirements of part

60 regarding their clarity and sufficiency to protect public health and

safety. NRC focused particular attention on any matters that may be

ambiguous, insufficient for their intended purpose, or inconsistent

with other expressions of its regulatory policy. Independently, DOE

conducted a similar review of part 60.

The NRC review identified deficiencies regarding the clarity and

sufficiency of the current part 60 requirements to protect public

health and safety for the full range of credible conditions or events

that may occur at an operating repository, including those low-

probability events that have potentially serious consequences. NRC also

noted that certain elements of existing part 60 differ from counterpart

requirements in other NRC rules where greater consistency in language

would be beneficial. DOE's independent review of Part 60 requirements

identified similar deficiencies in these requirements. To address these

issues, DOE filed a petition for rulemaking (PRM), PRM-60-3, on April

19, 1990.

In response to the DOE petition and the results of the NRC review

of part 60, the Commission published a proposed rule for public comment

in the Federal Register on March 22, 1995 (60 FR 15180) to clarify the

requirements for protection of public health and safety related to

activities conducted at a GROA before its permanent closure. In

particular, the proposed rule provided new and modified definitions for

certain terms (including the definition of ``important to safety,''

with reference to structures, systems, and components), dose criteria

for accident conditions, and requirements for the establishment of a

preclosure controlled area from which members of the public can be

excluded when necessary. In an accompanying notice (March 22, 1995; 60

FR 15190) the Commission also granted in part, and denied in part, the

specific proposals in the DOE petition. For a fuller discussion of the

PRM, the proposed rule, and the partial grant/partial denial of the DOE

petition, see the Federal Register notices cited above. As noted in the

Federal Register notice for the proposed rule (60 FR 15180) and as

intended in subsequent discussions in this notice, unless the specific

context suggests otherwise, the terms ``provisions,'' ``requirements,''

``standards,'' and ``criteria'' are generally used interchangeably; the

term ``limit'' (as in ``dose limit'') is generally used to refer to a

specific type of requirement or criterion; and the term ``rule'' is

generally used to refer to the entire set of requirements or criteria

(e.g., part 60). This final rule completes NRC action related to PRM-

60-3.

Lastly, the Commission notes that, consistent with the mandates of

the Energy Policy Act of 1992, the Environmental Protection Agency

(EPA) is developing site-specific environmental radiation protection

standards for a potential repository at Yucca Mountain, Nevada. In this

regard, the Act specifies that, within one year after promulgation of

the EPA standards, the Commission must promulgate a rule so that

Commission regulations are consistent with the new EPA standards.

Although the primary focus of the new EPA standards is on the

postclosure period of repository performance, the staff will ensure

that the current modifications to part 60 proposed herein, which focus

on the period of repository operations before permanent closure, are

consistent with the new EPA standards. To the extent any

inconsistencies between NRC and EPA requirements are identified, they

will be addressed in the planned future rulemaking by NRC to address

new EPA standards.

Public Comments on the Proposed Rule

A period of 90 days was specified in the Federal Register for

public comments on the proposed rule. The Commission specifically

sought public comments on: (1) The appropriateness of the proposed 0.05

Sv (5 rem) dose limit in new 10 CFR 60.136 as the repository design

basis for protection of public health and safety during accident

conditions, and (2) the rationale supporting the proposed 0.05 Sv (5

rem) dose limit. Ten sets of comments were received on the proposed

rule from the following organizations and individuals: (1) The Clean

Water Fund of North Carolina (CWFNC); (2) Mr. Vernon J. Brechin; (3)

DOE, Office of Civilian Radioactive Waste Management; (4) EPA, Office

of Federal Activities; (5) Nye County, Nevada, Nuclear Waste Repository

Project Office; (6) Virginia Power Company; (7) Nuclear Energy

Institute (NEI); (8) Environmental Coalition on Nuclear Power (ECNP);

(9) Wisconsin Electric Power Company; and (10) Mr. Marvin I. Lewis.

The principal issues raised in the comments are summarized below.

(Comments that are duplicative, editorial, or beyond the scope of the

rulemaking are not discussed herein but have been considered in the

analysis of the public comments.) For the reasons indicated, the

Commission has decided to adopt the amendments substantially in the

form proposed in the March 22, 1995, Federal Register notice (60 FR

15180) but with the changes noted that reflect the Commission's

analysis of the public comments.

1. Controlled Area--Waste Isolation

DOE noted that the supplementary information in the proposed rule

referred to the ``controlled area'' as one ``* * * (within which waste

isolation is to be ensured after permanent closure),'' DOE observed

that this is inconsistent with the part 60 definition of ``controlled

area,'' which does not refer to waste isolation. DOE recommended that

the Commission delete the parenthetical phrase in the supplementary

information.

The Commission agrees that the parenthetical phrase does not

properly characterize the definition of ``controlled area.'' However,

rather than deleting the parenthetical phrase altogether, the

Commission has modified the phrase to accurately reflect the definition

of ``controlled area'' and its focus on postclosure activities.

2. Multiple Failure Scenarios

DOE noted that the supplementary information under Sec. 60.136

seemed to indicate that multiple independent failure scenarios would be

considered to be Category 2 design basis events and observed that,

typically, nuclear safety analyses are not required to assume multiple

failures of safety-related systems unless they are all credible

consequences of the initiating event. DOE recommended that the

Commission clarify how it intends to review the acceptability of

repository systems, structures, and components in the context of the

new rule.

The Commission agrees with this comment and has revised the

supplementary information to clarify how it intends to review the

analysis in the DOE license application to demonstrate compliance with

the requirements of Sec. 60.136.

3. Probability Bounds for Design Basis Events

In the Section-by-Section Analysis of Sec. 60.136 in the proposed

rule, the Commission indicated that the lower

[[Page 64259]]

bound for Category 2 design basis events is on the order of 1 x 10-

-9 per year (i.e., events with probabilities of occurrence less

than 1 x 10--9 per year would generally be screened from further

consideration due to their negligible contribution to overall risk).

DOE and NEI objected that this lower bound is much too low and

unjustified. DOE recommended a lower bound of 1 x 10-6 per year

and NEI recommended a lower bound in the range of 1 x 10--6 per

year to 1 x 10--7 per year. On the other hand, ECNP recommended

that the most improbable sequences and combinations of events and

accidents (Category 2 and beyond) should be evaluated in repository

accident analysis.

The Commission agrees with DOE and NEI that the lower probability

bound discussed in the proposed rule for Category 2 design basis events

is too low and is unjustified. The Commission considers that, on the

basis of repository risk perspective, a lower probability bound of

1 x 10--6 per year is appropriate for these events. The Commission

recognizes that the estimated consequences from Category 2 design basis

events are somewhat limited and would not likely exceed several tenths

of Sv (several tens of rem). At this consequence level, the estimated

risk of cancer fatality from events with a probability lower than

1 x 10--6 per year is less than 1 x 10--8 per year. To put

this risk in perspective, the International Commission on Radiological

Protection 1 notes that a fatal cancer risk in the range of

1 x 10--6 to 1 x 10--5 per year from exposure to radiation

would likely be acceptable to members of the public. As such, Category

2 design basis events which result in fatal cancer risks on the order

of 1 x 10--8 per year or lower do not contribute significantly to

individual risk. Accordingly, events with probabilities of occurrence

lower than 1 x 10--6 per year can be screened from further

consideration in repository risk analysis.

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\1\ Recommendations of the International Commission on

Radiological Protection. ICRP Publication 26, January 1977.

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The Commission has revised the Section-by-Section Analysis of

Sec. 60.136 to reflect a lower bound for Category 2 design basis events

on the order of 1 x 10-6 per year.

4. Definition of ``Important to Safety''--Engineered Features

DOE noted that the phrase ``engineered structures, systems, and

components,'' currently in the definition of ``important to safety,''

was removed from the new definition and observed that it is clearly the

intent of the regulation to apply the definition to engineered systems,

not natural systems.

The Commission agrees with this comment and has revised the

definition of ``important to safety'' to clarify this intent.

5. Applicability of Environmental Protection Agency Standards to the

Management and Storage of High-Level Waste

DOE stated that the proposed rule did not address all of the

regulatory uncertainty associated with dose limits for design basis

events because both the existing rule and the proposed rule appear to

require compliance with both EPA radiation protection standards and

part 20 radiation standards and there is an inconsistency between these

two standards. Virginia Power noted that the definition of ``important

to safety'' establishes the part 20 limits that are referenced in 10

CFR 60.111(a) as the acceptance criteria for the Category 1 design

basis events and concluded that this seems to be inappropriate.

Virginia Power stated that part 20 establishes occupational dose limits

and radiation dose limits for members of the public, that these limits

are expressed as annual limits, and that these limits are associated

with normal licensed activities--not design basis events. Virginia

Power considered that it is not appropriate to use part 20 limits to

evaluate specific events. Virginia Power further considered that

acceptance criteria for design basis events are associated with the

specific consequences of those events, as for example in Sec. 60.136

for the Category 2 design basis events, and that appropriate acceptance

criteria will need to be developed if Category 1 design basis events

are retained by the final rule.

The Commission agrees with DOE that both the dose limits and the

methodology for calculating doses to members of the public in the EPA

standards differ from the dose limits and methodology for calculating

doses to members of the public in part 20, subpart D. Notwithstanding

the differences between these standards, the staff does not consider

that there is any regulatory uncertainty regarding applicable dose

limits for Category 1 design basis events. In DOE's demonstration of

compliance, either the EPA standards or the part 20 standards may be

more limiting or controlling than the other, but that does not relieve

DOE of the requirement to comply with both standards. As such, the

Commission has made no changes to the proposed rule to address DOE's

concerns about the differences between part 20 and the EPA standards.

The Commission disagrees with Virginia Power that part 20 limits

are inappropriate. The Commission's numerical radiation protection

standards are codified in part 20 and apply to operations at a geologic

repository by virtue of 10 CFR 20.1002 and Sec. 60.111(a). However, it

is not the Commission's intent that it is necessary to use the annual

limits in part 20 to evaluate specific Category 1 design basis events

on an individual basis. Instead the Commission intends that the sum of

the annual doses, exposures, and releases from all Category 1 design

basis events shall not exceed the limits specified in part 20 and in

the EPA standards.

6. Preclosure Controlled Area

DOE expressed a concern that the use of the word ``immediately'' in

the definition of ``preclosure controlled area'' could lead to an

implication that the boundary must be next to the GROA. DOE also

expressed a concern that the use of the word ``nearest'' in

Sec. 60.136(b) (i.e., `` * * * no individual located on or beyond the

nearest boundary of the preclosure controlled area * * *'') is

confusing.

The Commission agrees with these comments and has: (1) deleted the

word ``immediately'' in the definition of ``preclosure controlled

area'' in 10 CFR 60.2, (2) changed the phrase ``nearest boundary'' to

``any point on the boundary'' in the definition of ``important to

safety'' in Sec. 60.2 and in the design requirements of the geological

repository operations area in Sec. 60.136(b).

7. Definition of Site

DOE recommended that the definition of ``site'' should include

``preclosure'' and ``postclosure controlled areas.''

The Commission agrees with this comment and has modified the

definition of ``site'' to reflect its meaning during the period before

permanent repository closure (i.e., the operational period), as well as

the period following permanent closure.

8. Effluent Control

DOE stated that, with the deletion of the term ``during normal

operations,'' the application of the part 20 effluent limits invoked by

Sec. 60.111(a) is not clear. DOE recommended that 10 CFR 60.132(c)(1)

be revised to clarify that the latter section is applicable only to

Category 1 design basis events.

The Commission agrees with this comment and has revised

Sec. 60.132(c)(1)

[[Page 64260]]

to clarify that this section is applicable only to Category 1 design

basis events.

9. Criticality Control

DOE noted that the Commission intended to clarify the requirements

pertaining to criticality control, currently in 10 CFR 60.131(b)(7),

but that some confusion concerning those requirements remains. DOE

pointed out that the proposed criticality control requirements in

Sec. 60.131(h) refer to ``isolation of radioactive waste,'' a phrase

with postclosure connotations, while noting that systems ``must be

designed for criticality safety assuming occurrence of design basis

events,'' a phrase which has preclosure implications. Furthermore, DOE

argued that the last sentence in Sec. 60.131(h) could be interpreted as

requiring a deterministic demonstration of criticality safety over the

entire period of regulatory concern. However, given the time frames

involved, DOE considered probabilistic analyses to be an essential part

of demonstrating long-term criticality safety.

The Commission considers that the applicability of the criticality

control requirements proposed in Sec. 60.131(h) is clear with respect

to preclosure considerations but agrees with DOE that uncertainty

remains with respect to the applicability of the criticality control

requirements to the postclosure period. However, the Commission intends

to address this remaining uncertainty in a future rulemaking to make

the NRC requirements consistent with the revised EPA standards that are

currently under development, as mandated by the Energy Policy Act of

1992. Accordingly, in this final rule, Sec. 60.131(h) is promulgated,

as proposed in the proposed rule.

10. The Use of the Terms ``Important to Safety,'' ``Accidents,''

``Normal Conditions,'' ``Anticipated Operational Occurrences,'' and

``Design Basis Events'' in part 60.

CWFNC stated that there was not any ambiguity in the current use of

the terms ``important to safety'' and ``accidents'' in part 60. ECNP

stated that the terms ``normal conditions,'' ``anticipated operational

occurrences,'' and ``accidents'' are not equivalent to nor adequately

described by the term ``design basis events.''

The Commission disagrees with CWFNC that there is no ambiguity in

the current use of the terms ``important to safety'' or ``accidents''

in part 60. The latter term is undefined in part 60, and there is

uncertainty about its meaning with respect to the range of events the

term encompasses. The full range of Category 1 design basis events

would not generally be considered as ``accidents,'' especially those

events occurring regularly or moderately frequently. However, certain

lower frequency Category 1 events, which occur one or more times during

the operating lifetime of a facility and are otherwise known as

``anticipated operational occurrences,'' have at times been identified

as ``accidents.'' But ``anticipated operational occurrences'' are

conditions of normal operation which are not to be confused with the

unlikely, but credible and potentially significant, Category 2 design

basis events. As such, the current definition of ``important to

safety'' is unclear with respect to its intended applicability to the

design of structures, systems, or components for normal operations,

including anticipated operational occurrences. Further, with the focus

on protection of members of the public in unrestricted areas, the

current definition of ``important to safety'' does not explicitly

address protection for the occupational work force. The uncertainty is

not related to interpreting the meaning of ``unrestricted area'' but,

rather, is related to the narrow focus of public exposure in

unrestricted areas. Lastly, the value of 0.005 Sv (0.5 rem) as a dose

limit in unrestricted areas for ``accident'' conditions lacks

consistency with a corresponding limit in Part 72 and with dose values

established as guidance for selected accidents (fuel handling and cask

drop events) at Part 50 facilities (commercial power reactors).

Notwithstanding the comments offered by ECNP, the Commission

considers that the definition of ``design basis events'' in the

proposed rule does adequately define that term and that the

supplementary information in the proposed rule does adequately describe

the relationship between the terms ``normal conditions,'' ``anticipated

operational occurrences,'' ``accidents,'' and ``design basis events.''

In this regard, it was the Commission's intent to supplant undefined

terms in the rule (i.e., ``normal conditions,'' ``anticipated

operational occurrences,'' and ``accidents'') with a defined term

(i.e., ``design basis events'').

For the above reasons, the Commission has not revised the

definitions in the proposed rule for ``design basis events.'' As

discussed in items 4 and 6 above, editorial changes have been made to

the definition of ``important to safety,'' but these changes are

unrelated to the arguments advanced by CWFNC or ECNP.

11. Radiation Protection Standards

CWFNC stated that a 0.005 Sv (0.5 rem) limit would not be overly

protective of public health and safety and there is no reason to seek a

weaker standard. CWFNC suggested modifying part 20 to clarify any

ambiguities in radiation protection standards for repositories. ECNP

offered a number of comments related to radiation protection standards:

The Commission should require DOE to provide design basis

accident analyses for more than undefined ``critical design basis

events, singly'' and should require demonstration that doses would be

kept far below the maximum permissible dose limits, with an as low as

is reasonably achievable requirement at least comparable with that for

operating reactors.

The part 60 limits must be much more stringent than for

operating nuclear facilities.

The limit of radiation exposure should be no higher than

the most restrictive exposure limit that EPA imposes for any licensee

or other source of regulated nuclear activity.

A 0.005 Sv (0.5 rem) limit should be impermissible for an

individual dose from a waste site.

The most stringent level of worker protection, better than

part 20, should be required.

Part 20 standards are not restrictive enough for the

purpose of public health protection with respect to the storage and

disposal of radioactive waste.

The definitional alteration of the term ``important to

safety'' is not adequate to assure health protection for the public

because the proposed Categories 1 and 2 numerical limits for radiation

exposures are based on standards that have failed to take into account

the noncancer but adverse health effects of chronic low-dose radiation

exposures that have been reported in the literature since development

of NRC's part 20 revision.

Extremely conservative radiation protection standards

should be utilized in repository design and performance criteria, and a

zero release facility design goal should be required for all

radioactive waste management.

An acceptable rationale for the 0.05 Sv (5 rem) dose limit

proposed in the proposed rule is totally absent.

The Commission acknowledges that the 0.005 Sv (0.5 rem) dose limit

in the definition of ``important to safety'' in the existing rule could

be construed to be an implicit basis for designing structures, systems,

and components to prevent or mitigate the consequences of accidents at

the boundary of the

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unrestricted area. On the other hand, the 0.005 Sv (0.5 rem) dose limit

could also be interpreted more narrowly, to identify only those

structures, systems, and components that are subject to additional

design requirements and a quality assurance program to ensure

performance of intended functions. See Sec. 60.131(b) and Sec. 60.151.

In short, the 0.005 Sv (0.5 rem) dose limit in the definition of

``important to safety'' in the existing rule is, in the Commission's

view, subject to conflicting interpretations.

As previously discussed, the Commission's comprehensive review of

part 60 identified deficiencies in both the clarity and sufficiency of

requirements to protect workers and public health and safety. Among the

identified deficiencies is the regulatory uncertainty created by

possible conflicting interpretations that could be given to the 0.005

Sv (0.5 rem) dose limit in the ``important to safety'' definition

described above and by the absence of an explicit design basis dose

limit in Subpart E of the existing rule. An objective of this

rulemaking is, therefore, to resolve the uncertainty in part 60, as

well as remedy the incomplete definition of ``important to safety''

that fails to address protection of both workers and members of the

public during Category 1 design basis events (i.e., ``normal

conditions,'' including ``anticipated operational occurrences''). The

Commission has addressed these deficiencies with the addition of new

Sec. 60.136, which now provides explicit design basis accident dose

criteria for repository structures, systems, and components, and

modification of the definition of ``important to safety'' to include

the broader interests of both worker and public health and safety for

the full range of conditions or events that may occur before repository

closure. The Commission believes that these amendments, as well as the

others as described herein, clarify and enhance the provisions in the

rule to protect worker and public health and safety.

It was not the intent of this rulemaking to modify, in any way, the

Commission's numerical radiation protection standards. As discussed

earlier, these standards are codified in part 20 and apply to

operations at a geologic repository by virtue of Sec. 20.1002, as well

as Sec. 60.111(a). The Commission believes that these standards

continue to be appropriate for its licensees and provide adequate

protection of worker and public health and safety at a repository. As

such, comments by CWFNC and ECNP about possible modifications to the

Commission's radiation protection standards as they would apply to an

operating repository are beyond the scope of this rulemaking.

The Commission agrees with ECNP that the term ``critical design

basis events'' is undefined and, in the Section-by-Section Analysis of

Sec. 60.21 of this final rule, has changed ``critical design basis

events'' to ``Category 2 design basis events.'' With regard to the

scope of design basis accidents that should be considered in the

license application, the Commission previously addressed this issue in

the discussion of probability bounds for Category 2 design basis events

and determined that events with probabilities of occurrence lower than

1 x 10-6 per year could be screened from further consideration due

to their negligible contribution to individual risk.

Regarding the rationale for the 0.05 Sv (5 rem) dose limit in

Sec. 60.136, the Commission continues to believe that the potential

risks to members of the public from an operating repository are very

small. In light of this limited risk, the 0.05 Sv (5 rem) dose limit

provides an adequate margin of safety and an appropriate basis for the

design of repository structures, systems, and components to prevent or

mitigate the consequences of low probability, but credible events. The

Commission's reasoning behind the 0.05 Sv (5 rem) dose limit can be

found in the Section-by-Section Analysis of Sec. 60.136 that appears

later in this notice.

12. Exclusion of the Public From Preclosure Controlled Area

Vernon J. Brechin objected to the use of the word ``can'' versus

``will'' in the description of preclosure controlled area.

The Commission disagrees with this comment. It is not the

Commission's intention to generally exclude members of the public from

the preclosure controlled area (which would be the ``controlled area''

as defined in 10 CFR 20.1003). However, access to the preclosure

controlled area can be limited by the licensee for any reason (not

necessarily one related to radiation protection). Within the preclosure

controlled area will be a ``restricted area'' (as defined in Sec. 60.2

and Sec. 20.1003). Access to a restricted area must be controlled for

purposes of radiation protection. Members of the public in the

preclosure controlled area will be subject to the dose limits for

members of the public in 10 CFR 20.1301. However, an individual who

receives occupational dose in the preclosure controlled area will be

subject to the occupational dose limits of part 20, subpart C. All

doses in a restricted area are occupational doses. The size of the

preclosure controlled area is not specified by the regulations because

it will be dependent upon the particular activities conducted during

the operational period.

13. Definition of Design Basis Events

Virginia Power and NEI recommended that the definition of ``design

basis events'' should make clear that the normal operations associated

with receiving, handling, packaging, storing, emplacing, and retrieving

high-level waste are not design basis events.

The Commission disagrees with this comment. It is the Commission's

intent that events occurring regularly or frequently during the course

of normal operations are considered as Category 1 design basis events.

Category 1 design basis events effectively embody repository activities

and conditions previously identified in part 60 as ``normal operations,

including anticipated operational occurrences.'' In this regard, the

Commission intends the part 20 dose limits to be applicable to the

conduct of repository activities, such as receiving, handling,

packaging, storing, placing, and retrieving high-level waste.

14. Definition of ``Important to Safety''--Function

Virginia Power noted that in the proposed rule, the definition of

``important to safety'' refers to ``* * * (1) to provide reasonable

assurance that high-level waste can be received, handled, packaged,

stored, emplaced, and retrieved without exceeding the requirements of

(10 CFR) 60.111(a) for Category 1 design basis events; or * * *.''

Virginia Power recommended that this part of the definition should be

revised to make it clear that the focus of important to safety is

design basis events and not the normal operations that are described by

the definition in the proposed rule.

The Commission disagrees with this comment. As explained in Item

13, the Commission intends that events occurring regularly or

frequently during the course of normal operations are considered as

Category 1 design basis events.

15. Definition of ``Important to Safety''--Quality Assurance Issues

Virginia Power and NEI stated that the definition of ``important to

safety'' proposed in the proposed rule would apply full Quality

Assurance (QA) requirements to almost every system and component of the

repository, and that the latter definition does not establish a graded

QA system to

[[Page 64262]]

properly distinguish systems that are ``important to safety'' and

ensure that the full QA program is only applied to those systems.

The Commission disagrees with this comment. When identifying items

``important to safety,'' if it is determined that a particular

structure, system, or component is essential to maintaining doses below

part 20 limits during normal operations (or during any Category 1

design basis event), then that structure, system, or component must be

designated as ``important to safety.'' The list of structures, systems,

and components ``important to safety,'' as well as the list of

engineered barriers ``important to waste isolation,'' are collectively

referred to as the ``Q-list'' and are subject to the QA provisions of

part 60, subpart G. The Commission supports a graded approach to

meeting the QA provisions of part 60. Such an approach is consistent

with the NRC staff's ``Technical Position on Items and Activities in

the High-Level Waste Geologic Repository Program Subject to QA

Requirements (NUREG-1318).'' The guidance given in that technical

position (TP) is still applicable under the rule's changes. The TP

describes a graded application of QA measures consistent with that

applied to other facilities (e.g., nuclear power reactors) licensed by

the Commission. In this regard, the application of QA program

requirements to repository structures, systems, and components would

generally be commensurate with their importance to safety.

16. Design Bases--Similarities Between GROA Facility and Other

Facilities Licensed by NRC

ECNP stated that it is wrong to liken design basis for a waste

repository (or long-term storage) facility to design basis for an

operating nuclear reactor or other contemporary nuclear facility

because of the longevity of the hazard and uncertainties of future

monitoring and control.

The Commission disagrees with this comment. The design bases

provided in the rule are for operations at the GROA and not for

postclosure performance. Because operations at the repository are

expected to be similar to operations at other facilities licensed by

the Commission (e.g., 10 CFR part 72 facilities), the Commission

believes that it is appropriate that their design bases be comparable.

17. The Phrase ``At All Times''

ECNP recommended that the phrase ``at all times'' should be

retained throughout part 60.

The Commission disagrees with this comment. The phrase ``at all

times'' was originally included in the regulation to emphasize the need

to design the GROA such that retrieval activities, if found necessary,

would be conducted in accordance with part 20. The Commission continues

to interpret the regulation in this manner but has removed the phrase

``at all times'' from Sec. 60.111 in the rule to clarify that the

limits of part 20 apply to Category 1 design basis events and that the

separate design bases of Sec. 60.136 apply for Category 2 design basis

events. Further, the Commission recognizes that conformance to the

regulations should not hinder any actions that are necessary to protect

public health and safety, such as lifesaving or maintaining confinement

of radioactive materials (May 21, 1991; 56 FR 23365). The phrase ``at

all times'' is ambiguous in this respect and was therefore removed.

18. As High as Reasonably Achievable (AHARA) Design Standard for the

GROA

ECNP recommended that NRC adopt an AHARA standard with respect to

criteria for the design of the GROA. ECNP states that the purpose of

such a standard would be to provide an extra measure of conservatism in

the design. ECNP further states that, for an operating nuclear

facility, regulatory changes over time that mandate tighter standards

and reduced emissions can be accommodated by means of backfitting, but

this is not so readily accomplished at a disposal facility.

The Commission disagrees with this comment and considers that the

requirements of part 60, as amended in this rulemaking, are sufficient

to ensure public health and safety. The Commission also considers that

backfitting, if necessary, can be accomplished at a disposal facility.

Section-by-Section Analysis

Section 60.2. Definitions

The amendments involve 10 definitions needed in part 60.

The term ``preclosure controlled area'' is new. It is essentially

the same as the term ``preclosure control area'' proposed by DOE in its

petition (PRM-60-3) and corresponds closely to the term ``controlled

area,'' as defined in 10 CFR 72.3. The term ``preclosure controlled

area'' is adopted because part 60 already refers to a ``controlled

area'' (which area has been committed to use as a geologic repository

and from which incompatible activities would be restricted following

permanent closure). The function of the new term is to delimit an area

over which the licensee exercises control of activities to meet

regulatory requirements. Control includes the power to exclude members

of the public, if necessary. Because part 60 (unlike part 72) involves

ongoing underground operations and timeframes of concern over centuries

and millennia, language in the definition is included that, consistent

with its function, limits the area to the surface and limits the

duration to the period up to, and including, permanent closure.

The existing term ``controlled area'' is renamed ``postclosure

controlled area,'' to avoid any confusion or misunderstanding about

this term in relation to its use in parts 20 and 72. However, no

substantive change is intended for the ``postclosure controlled area''

because this is a change in nomenclature only. Consistent with this

nomenclature change, the term ``controlled area'' is changed to

``postclosure controlled area,'' where it appears in the definitions

for ``accessible environment,'' ``disturbed zone,'' and ``site.''

The term ``important to safety'' is amended to address the issues

previously discussed. The existing provision is unclear and fails to

ensure proper levels of protection of public and worker health and

safety for the broad range of conditions or events that might occur at

a repository site. This is an important term because it is the

predicate for required design features as well as required quality

assurance measures that provide defense-in-depth. The Commission is

retaining the quantitative features of the existing definition but is

specifying different numerical limits for each of the two categories (1

and 2) of design basis events. The structures, systems, and components

``important to safety'' are those necessary: (1) To provide reasonable

assurance that the requirements of Sec. 60.111(a) would be observed for

Category 1 design basis events; or (2) to prevent or mitigate Category

2 design basis events that could result in doses equal to, or greater

than, the values specified in (new) Sec. 60.136 to any individual

located on or beyond any point on the boundary of the preclosure

controlled area.

Although the term ``design bases'' appears in existing part 60, in

Sec. 60.21(c)(2), it was not defined. As the previous discussion makes

clear, ``design bases'' should be understood in relation to that range

of events, including external natural or man-induced events, that is

taken into account in the design, and, in particular, in relation to

conditions that could result in radiological consequences

[[Page 64263]]

beyond specified limits. The definition in part 72 is inserted, without

change, into the list of defined terms in Sec. 60.2.

The inclusion of a definition of ``design basis events'' serves two

purposes. First, it identifies a set of events (referred to elsewhere

as Category 1 design basis events) that must be taken into account in

demonstrating compliance with the requirement to show, with reasonable

assurance, that the provisions of part 20 will be met. (This set of

events is described as ``* * * those natural and human-induced events

that are reasonably likely to occur regularly, moderately frequently,

or one or more times before permanent closure of the geologic

repository operations area.'') Second, it identifies an additional set

of events (previously referred to as Category 2 design basis events)

that must be taken into account in applying the Commission's defense-

in-depth philosophy. (This set of events is described as those ``* * *

other natural and human-induced events that are considered unlikely,

but sufficiently credible to warrant consideration, taking into account

the potential for significant radiological impacts on public health and

safety.'') The Commission recognizes that the criterion of

``sufficiently credible to warrant consideration'' is inexact, leaving

its application to a consideration of the particular site and design

that are the subjects of a license application. Generally, the

Commission would expect that such design basis events would include as

broad a range of external phenomena as would be taken into account in

defining the design basis for other regulated facilities, including

nuclear reactors. The Commission would also expect that the analysis of

a specific design basis event would require an analysis which includes

an initiating event (e.g., an earthquake) and the associated

combinations of repository system or component failures that can

potentially lead to exposure of the public to radiation.

The definitions of ``restricted area'' and ``unrestricted area''

are amended to conform with the definitions in part 20. The current

definitions in part 60 do not precisely conform to the current part 20

because no change was made to these part 60 definitions when part 20

was revised.

The amendments of Sec. 60.2 adopted in this final rule differ from

the amendments of Sec. 60.2 proposed in the proposed rule (March 22,

1995; 60 FR 15180) in the following respects: (1) The revised

definitions of ``restricted area'' and ``unrestricted area'' were not

proposed in the proposed rule; (2) in the definition of ``important to

safety,'' the phrases ``features of the repository'' and ``nearest

boundary'' in the proposed rule were changed to ``engineered features

of the repository'' and ``any point on the boundary,'' respectively;

(3) in the definition of ``preclosure controlled area'', the phrase

``immediately surrounding the geologic repository operations area'' in

the proposed rule was changed to ``surrounding the GROA''; and (4) in

the definition of ``site'', the phrase ``location of the postclosure

controlled area'' was changed to ``location of the preclosure

controlled area, or of the postclosure controlled area, or both.'' The

rationale for the revised definitions of ``restricted area'' and

``unrestricted area'' is provided in the preceding paragraph. The

rationale for the other changes is discussed under ``Response to Public

Comments on the Proposed Rule.''

Section 60.8. Information Collection Requirements: OMB Approval

NRC is updating 10 CFR 60.8, ``Information Collection Requirements:

OMB Approval,'' to reflect the fact that subsequent to the original

issuance of part 60, NRC requested, and obtained Office of Management

and Budget (OMB) approval for the part 60 ``Information Collection

Requirements.'' Section 60.8 was to be corrected the first time other

revisions were made.

The amendment of Sec. 60.8 adopted in this final rule differs from

the amendment of Sec. 60.8 in the proposed rule (60 FR 15180) in that

the term ``Paperwork Reduction Act of 1980,'' in the proposed rule, has

been changed to the term ``Paperwork Reduction Act of 1995'' in the

final rule.

Section 60.21. Content of Application

The DOE petition suggested that provision for accident analysis

might be accomplished by amendment of Sec. 60.111. The Commission,

instead, is requiring an accident analysis as part of the content of

the application section (i.e., Sec. 60.21). The language requires that

the application address the potential dose, to any individual located

on or beyond any point on the preclosure controlled area boundary, that

is attributable to Category 2 design basis events. The procedure that

is envisaged is that the applicant would address the Category 2 design

basis events, singly, and demonstrate, by its analysis, that the doses

to any individual located on or beyond any point on the preclosure

controlled area boundary would be in accordance with the applicable

requirements. The language serves the same purpose as the counterpart

section of part 72 (namely, 10 CFR 72.24[m]).

The final rule also reflects the position that the applicant must

demonstrate that the requirements of part 20 and the EPA standards will

be met, assuming the occurrence of Category 1 design basis events. For

this analysis, the applicant would calculate the sum of the doses,

exposures, and releases from all Category 1 design basis events to

ensure that these results do not exceed the limits specified in part 20

and in the EPA standards.

The Commission also is eliminating certain terms in Part 60 that

are undefined and may be subject to differing interpretations--

specifically, the terms ``normal conditions,'' ``anticipated

operational occurrences,'' and ``accidents.'' These terms are

supplanted by the new term ``design basis events.'' Besides enhancing

clarity of expression, the new language better reflects the articulated

regulatory framework. Lastly, where the term ``controlled area''

appears in the language of this section, it is changed to ``postclosure

controlled area.''

Section 60.43. License Specification

The term ``controlled area'' is changed to ``postclosure controlled

area.''

Section 60.46. Particular Activities Requiring License Amendment

The term ``controlled area'' is changed to ``postclosure controlled

area.''

Section 60.51. License Amendment for Permanent Closure

The term ``controlled area'' is changed to ``postclosure controlled

area.''

Section 60.102. Concepts

The term ``controlled area'' is changed to ``postclosure controlled

area.''

Section 60.111. Performance of the Geologic Repository Operations Area

Through Permanent Closure

The Commission is deleting the phrase ``at all times'' from the

performance objective of Sec. 60.111(a). This change clarifies that

this requirement does not apply to radiation exposures, levels, and

releases from Category 2 design basis events.

Section 60.121. Requirements for Ownership and Control of Interests in

Land

The term ``controlled area'' is changed to ``postclosure controlled

area.''

Section 60.122. Siting Criteria

The term ``controlled area'' is changed to ``postclosure controlled

area.''

[[Page 64264]]

Section 60.130. Scope of Design Criteria for the Geologic Repository

Operations Area

The Commission is modifying the title of this section to the term

``General Considerations'' and is adding clarifying language, to the

existing discussion, to indicate that Secs. 60.131 through 60.134

specify the minimum criteria for the design of those structures,

systems, and components important to safety, or important to waste

isolation. These changes are necessary to provide consistency with the

modified definition of ``important to safety'' (Sec. 60.2), as well as

to clarify the purpose of these criteria. These changes also provide

consistency with the corresponding ``minimum'' design criteria, for an

MRS, in part 72.

Section 60.131. General Design Criteria for the Geologic Repository

Operations Area

Consistent with the modifications to Sec. 60.130, as described

above, the Commission is deleting the reference to ``Structures,

systems, and components important to safety,'' in the title of

Sec. 60.131(b), and re-numbering the current criteria in

Secs. 60.131(b)(1) through 60.131(b)(10), as appropriate. This change

eliminates the confusion in the existing rule related to the

identification of only the criteria in Sec. 60.131(b) as ``important to

safety.'' It also resolves the present incongruity with

Sec. 60.131(b)(7), ``criticality control,'' regarding the reference to

waste ``isolation'' (a postclosure term) in the requirement.

The current rule employs the term ``normal and accident

conditions,'' or similar expression, in several places. However, the

conditions that must be addressed under this language are not well-

defined. The Commission is remedying this situation by replacing

current terminology with references to ``design basis events,'' thereby

ensuring that the design appropriately takes into account the

consequences of all design basis events (i.e., as discussed in this

document, Category 1 and 2 design basis events). Accordingly,

paragraphs (b)(5)(i), (b)(7), and (b)(8) are modified for this section.

The Commission also is revising the language in Sec. 60.131(b)(1),

which refers to ``anticipated'' natural phenomena and environmental

conditions, so as to encompass all design basis events. The ``necessary

safety functions'' that must be accommodated in the design, pursuant to

that paragraph, include whatever is necessary to meet the quantitative

limits set out in the Commission's rules (i.e., in Sec. 60.111(a) and

Sec. 60.136).

As discussed under ``Public Comments on the Proposed Rule,'' the

Commission considers the applicability of the criticality control

requirements in Sec. 60.131(h) to be clear with respect to preclosure

considerations. The Commission also believes that uncertainty remains

with respect to the applicability of the criticality control

requirements to the postclosure period. The Commission intends to

address the remaining uncertainty in a future rulemaking to make the

NRC requirements consistent with the revised EPA standards that are

currently under development, as mandated by the Energy Policy Act of

1992.

Section 60.132. Additional Design Criteria for Surface Facilities in

the Geologic Repository Operations Area

Section 60.132(c)(1) requires that the surface facilities must be

``* * * designed to control the release of radioactive materials in

effluents during normal operations so as to meet the performance

objectives of Sec. 60.111(a).'' The design should ordinarily be

sufficient to provide reasonable assurance of meeting part 20 not only

during normal operations, but even for events that are likely to occur

moderately frequently or one or more times before permanent closure of

the geologic repository (i.e., all Category 1 design basis events).

Deleting the phrase ``during normal operations,'' broadens the scope of

this provision to reflect the Commission's intent more accurately.

The amendment of Sec. 60.132 adopted in this final rule differs

from the amendment of Sec. 60.132 in the proposed rule in that the

phrase ``in effluents'' in the proposed rule was changed to ``in

effluents during Category 1 design basis events'' in the final rule.

The rationale for this change was discussed in the ``Response to Public

Comments on the Proposed Rule.''

Section 60.133. Additional Design Criteria for the Underground

Facility

As in the case of the changes to 10 CFR 60.131, a reference to

design basis events is substituted for the less precise ``normal

operations and * * * accident conditions.''

Section 60.136. Preclosure Controlled Area

The final rule adopts the petitioner's concept of a preclosure

control area under the name ``preclosure controlled area.'' The term

delimits an area over which the licensee exercises control of

activities to meet regulatory requirements. Control would include the

ability to exclude members of the public, if necessary. The zone, and

related dose limits, would also be used to analyze and identify

structures, systems, and components that are important to safety under

unusual conditions that have heretofore been characterized as Category

2 design basis events--credible, yet not likely to occur during the

period of operations. The issue that is presented concerns the dose

limits to ensure that the consequences of any events which occur

present no unreasonable risk to the health and safety of the public.

(Releases resulting from Category 1 design basis events would not be

permitted to cause doses exceeding the limits of part 20.) The

Commission adopts the basic provisions of part 72--namely, a 0.05 Sv (5

rem) dose limit, on or beyond the preclosure controlled area boundary--

as modified to reflect the part 20 system of dose limits (see

Sec. 20.1201[a]). In addition to providing for separate dose limits for

individual organs and tissue, the lens of the eye, and the skin, the

use of ``total effective dose equivalent'' (TEDE) in part 20 explicitly

accounts for exposures via the ingestion and inhalation dose pathways.

Modification of the 0.05 Sv (5 rem) dose limit, to reflect the part

20 system of dose limits, results in a family of dose limits: A TEDE of

0.05 Sv (5 rem); or the sum of the deep-dose equivalent and the

committed dose equivalent to any individual organ or tissue (other than

the lens of the eye) of 0.5 Sv (50 rem); an eye dose equivalent of 0.15

Sv (15 rem); and a shallow dose equivalent, to skin, of 0.5 Sv (50

rem).2 The eye and skin dose limits are adequate to ensure that no

observable effects (e.g., induction of cataracts in the lens of the

eye) will occur as a result of any accidental radiation exposure. In

implementing this provision, dose calculations should be made solely

with reference to the consequence of the specific Category 2 design

basis event, not cumulatively with other design basis events. To

clarify this matter further, the analysis of a specific Category 2

design basis event would require an analysis which includes an

initiating event (e.g., an earthquake) and the associated combinations

of repository system or component failures that can potentially lead to

exposure of the public to radiation. An example design basis event is a

postulated earthquake (the initiating event) which results in: (1) The

failure of a crane lifting a spent fuel waste package inside a waste

handling building, (2) damage to the building ventilation filtration

system, (3) the drop and breach of the

[[Page 64265]]

waste package, (4) damage to the spent fuel, (5) partitioning of a

fraction of the radionuclide inventory to the building atmosphere, (6)

release of some radioactive material through the damaged ventilation

filtration system, and (7) public exposure to the released radioactive

material. It should be noted that it is not necessary to assume

multiple failures of safety-related systems unless these multiple

failures are credible consequences of the initiating event. An analysis

of a specific event for a real repository would be dependent on the

particular features of the facility design and related operating

procedures. In general, credit for the proper functioning of repository

structures, systems, and components in an analysis would be

commensurate with the merits of the design. In the example cited above,

a waste package designated ``important to safety'' would not

necessarily be assumed to breach in a drop event if the maximum

hypothetical drop falls within the design parameters of the waste

package to withstand such an event. Similarly, repository ventilation

filtration systems would be analyzed for their capability to withstand

natural phenomena (e.g., earthquakes) and detect, isolate, or filter

radioactive material in ventilation flow.

---------------------------------------------------------------------------

\2\ Radiation exposure terminology is as used in part 20 (56 FR

23360; May 21, 1991).

---------------------------------------------------------------------------

The only other noteworthy deviation from part 72 is to refer in

Sec. 60.136 to doses attributable to any ``Category 2 design basis

event'' whereas the corresponding section (i.e., 10 CFR 72.106) in part

72 refers to doses attributable to any ``design basis accident.'' The

term ``design basis event'' is used because it is a defined term in

part 60. The change in terminology is not intended to be one of

substance as Category 2 design basis events would generally be

considered as accidents.

The 0.05 Sv (5 rem) dose limit is being adopted by the Commission

as the appropriate design basis for protection of public health and

safety from Category 2 design basis events at a GROA and will harmonize

part 60 with part 72. In this regard, the Commission notes that part 72

applies to those facilities (MRS installations) most similar to the

surface facilities of a repository and for which the kinds of design

basis events are also expected to be similar. Further, the dose limit

is consistent with dose values (0.06 Sv (6 rem) to the whole body)

established as guidance for both fuel-handling accidents and spent-fuel

cask-drop accidents at nuclear power plants.3 Moreover, the dose

limit is consistent with the accident-dose value (0.05 Sv (5 rem)

effective dose equivalent) proposed by DOE in its PRM.

---------------------------------------------------------------------------

\3\ NUREG-0800, ``Standard Review Plan for the Review of Safety

Analysis Reports for Nuclear Power Plants,'' June 1987.

---------------------------------------------------------------------------

However, while consistency between the proposed 0.05 Sv (5 rem)

dose limit for part 60 and other Commission rules or guidance documents

is important, consistency alone does not necessarily ensure that there

would be no unreasonable risk to the health and safety of the public

associated with the proposed limit. As such, a perspective is provided

on the risks associated with an operational repository and the

appropriateness of the proposed 0.05 Sv (5 rem) dose limit as the

design basis for protection of public health and safety from Category 2

design basis events.

Based on estimates provided by the National Council on Radiation

Protection and Measurements 4, the lifetime risk to individuals in

the general population is 0.05 fatal cancers per Sv of exposure.

Therefore, the lifetime risk of fatal cancer from an assumed 0.05 Sv (5

rem) exposure resulting from a postulated Category 2 design basis event

is 0.0025 (i.e., 2.5 x 10-3 ) per individual exposed. While this

assessment provides perspective on the risk associated with a

hypothetical exposure of a 0.05 Sv (5 rem) dose, it does not provide

perspective on the estimated actual risk associated with the spectrum

of possible Category 2 design basis events at a repository during its

operational lifetime (estimated to be about 100 years).

---------------------------------------------------------------------------

\4\ National Council on Radiation Protection and Measurements,

``Risk Estimates for Radiation Protection,'' NCRP Report No. 115,

December 31, 1993.

---------------------------------------------------------------------------

Perspective on actual risk must include consideration of the

frequencies (i.e., probabilities) of occurrence of these events, as

well as their consequences, as ``risk'' is defined as ``the probability

of an event times its consequences.'' With respect to the range of

probabilities of Category 2 design basis events, the upper bound is

roughly 1 x 10-2 per year (i.e., events with probabilities of

occurrence greater than 1 x 10-2 per year would generally be

considered to be Category 1 events). Accordingly, assuming event

consequences equivalent to the 0.05 Sv (5 rem) dose limit for part 60,

the hypothetical upper bound on individual risk is 2.5 x 10-5

fatal cancers per year. To put this risk in perspective, the

International Commission on Radiological Protection 5 notes that,

based on a review of information related to risks regularly accepted in

everyday life for stochastic phenomena, a fatal cancer risk in the

range of 1 x 10-6 to 1 x 10-5 per year from exposure to

radiation would likely be acceptable to individual members of the

public. Thus, while the risk associated with the consequences of a

repository event at the dose limit and upper bound probability of

occurrence exceeds this range by a small factor, and is at a level that

the Commission considers safe for occupational exposures, the

Commission believes this result significantly overestimates the actual

risk of an operating repository. Similarly, the Commission considers

that the lower bound of Category 2 design basis events is on the order

of 1 x 10-6 per year (i.e., events with probabilities of

occurrence less than 1 x 10-6 per year would generally be screened

from further consideration due to their negligible contribution to

overall risk). In the proposed rule (March 22, 1995; 60 FR 15180), the

Commission had considered a probability of occurrence of 1 x 10-9

per year as an appropriate lower bound. However, upon further analysis

as discussed below, the Commission considers that a lower bound of 1 x

10-9 per year is too low and unjustified, and that a lower bound

of 1 x 10-6 per year is appropriate. Screening out events with

probabilities of less than 1 x 10-6 is expected to provide

conservative estimates of risk. A higher screening criterion could

probably be justified given the magnitude of the consequences and risks

from this facility, but this criterion is not expected to cause an

excessive analytical burden for demonstrating compliance with

Sec. 60.136, consistent with the Commission's guidance on the

application of probability risk assessment methods in licensing. It is

important to note that the arguments advanced for this screening

criterion apply solely to the period of repository operations before

permanent closure.

---------------------------------------------------------------------------

\5\ Recommendations of the International Commission on

Radiological Protection. ICRP Publication 26, January 1977.

---------------------------------------------------------------------------

Assuming bounding repository event consequences of roughly 0.2 Sv

(20 rem), a lifetime risk to individuals in the general population of

0.05 fatal cancers per Sv of exposure, and a lower bound of 1 x

10-6 per year for the probability of occurrence of Category 2

design basis events, the estimated risk of cancer fatality from these

low probability events would be 1 x 10-8 per year. Events which

result in risks at or below

[[Page 64266]]

this level do not contribute significantly to repository risk to an

individual and, as such, can be neglected in the overall risk

assessment.

Perspective on actual repository risk can be obtained by developing

an understanding of the spectrum of potential Category 2 design basis

events and estimating the consequences of these sequences, as well as

their probabilities of occurrence. In this regard, the Commission

recognizes that there is no high-level waste repository operating

experience, and that only conceptual designs have been developed for

these facilities. Nonetheless, some perspective can be gained from the

preliminary risk assessment by DOE 6 of a conceptual design for a

repository at Yucca Mountain, Nevada, as well as from consideration of

risk assessments of selected U.S. nuclear power plants.7

---------------------------------------------------------------------------

\6\ U.S. Department of Energy, ``Site Characterization Plan,

Yucca Mountain Site, Nevada Research and Development Area, Nevada,''

DOE/RW-0199, December 1988.

\7\ NUREG-1150, ``Severe Accident Risks: An Assessment for Five

U.S. Nuclear Power Plants,'' December 1990.

---------------------------------------------------------------------------

Consistent with risk assessments for nuclear power plants, the

spectrum of possible repository design basis events includes both

internally and externally initiated events. Internally initiated events

would include waste transporter collisions, crane failures or other

types of fuel assembly, waste package or cask drop events, building or

facility exhaust filter fires, and exhaust filter bypass or failure.

Externally initiated events would include those resulting from

earthquakes, tornados, and flooding. Regardless of the type or nature

of the initiating event, the Commission believes that, for several

reasons, both the variety of credible events and the resulting

potential consequences to members of the public will be somewhat

limited at repository facilities. First, in comparison with a nuclear

power plant, an operating repository is a relatively simple facility in

which the primary activities are waste receipt, handling, storage, and

emplacement. A repository does not require the variety and complexity

of active systems necessary to support an operating nuclear power

plant. Further, the conditions are not present at a repository to

generate a radioactive source term of a magnitude that, however

unlikely, is potentially capable at a nuclear power plant (e.g., from a

postulated loss of coolant event). As such, the estimated consequences

resulting from limited source term generation at a repository would be

correspondingly limited. This conclusion is consistent with the results

of the aforementioned preliminary risk assessment by DOE of a

conceptual repository design at Yucca Mountain, Nevada. In that

assessment, DOE considered 149 events for a variety of internally and

externally initiated events. Of the 149 events, only 7 resulted in

offsite doses in excess of 0.005 Sv (0.5 rem) to the critical organs of

a maximally exposed individual and also had associated probabilities of

occurrence greater than 1 x 10-9 per year. The highest estimated

offsite dose from the DOE risk assessment was 0.021 Sv (2.1 rem) with

an associated probability of occurrence of 5 x 10-7 per year.

The dose estimates of the DOE risk assessment are only reflective

of a conceptual design for a repository at Yucca Mountain, Nevada.

Nonetheless, the Commission believes they provide perspective on the

magnitude of the estimated consequences to members of the public from

postulated Category 2 design basis events, and that variations in

repository design or site selection would not likely vary these

estimates by more than an order of magnitude. The results of the DOE

risk assessment also provide some perspective on the estimated

probabilities of occurrence of the postulated repository design basis

events and, as such, perspective on actual risk from an operating

repository.

In general, the Commission would expect the potential higher

consequence events to have correspondingly lower probabilities of

occurrence. This expectation is consistent with the results of the DOE

risk assessment as the estimated probabilities of occurrence for the

seven events which resulted in offsite doses in excess of 0.005 Sv (0.5

rem) vary from 1 x 10-9 to 5 x 10-6 per year. The

corollary to this is the expectation that higher frequency events would

have correspondingly lower offsite consequences, and perspective on

actual risk from an operating repository necessitates consideration of

these events, as well as lower frequency events. Review of the DOE risk

assessment indicates that some higher frequency, but lower consequence,

events are just as important to actual risk as the lower frequency, but

higher consequence, events. With respect to actual risk from the broad

spectrum of all events considered in the DOE risk assessment, the

estimated actual risk of an operating repository is roughly two to

three orders of magnitude lower than the range of fatal cancer risks

that would likely be acceptable to members of the public (i.e., a fatal

cancer risk of 1 x 10-6 to 1 x 10-5 per year as noted in

ICRP Publication 26).

With respect to the appropriateness of the proposed 0.05 Sv (5 rem)

dose limit for Part 60 as the design basis for protection of public

health and safety from Category 2 design basis events, the DOE risk

assessment indicates the potential for events with offsite consequences

on the order of several hundredths to several tenths of Sv (several rem

to several tens of rem), depending on design and siting factors. The

event consequences in this range, coupled with the estimated event

probabilities of occurrence, result in estimated risks that would

likely be acceptable to members of the public. However, given the lack

of repository design, siting and operating experience and the

supporting data base for probabilistic risk assessment, the Commission

believes there is considerable uncertainty in the estimates of both the

consequences and the probabilities of occurrence of postulated Category

2 design basis events. As such, the Commission believes that

establishing a dose limit in Part 60 to the 0.05 Sv (5 rem) value would

provide an adequate margin of safety and an appropriate design basis

for protection of members of the public from unlikely, but credible

events. Further, the Commission believes that a single dose limit is

appropriate for the broad range of possible event frequencies, given

the limited potential for offsite consequences at repository

facilities.

Lastly, the amendments of Sec. 60.136 adopted in this final rule

differ slightly from the amendments of Sec. 60.136 proposed in the

proposed rule (60 FR 15180) in that the phrase ``on or beyond the

nearest boundary'' in the proposed rule was changed to ``on or beyond

any point on the boundary'' in the final rule and the phrase ``may not

exceed'' in the proposed rule was changed to ``shall not exceed'' in

the final rule. The rationale for the latter change is to improve

clarity and the rationale for the former change was discussed earlier

in the ``Response to Public Comments on the Proposed Rule.''

Section 60.183. Criminal Penalties

In the proposed rule, a conforming change was made to this section

to include Sec. 60.136 (pertaining to the preclosure controlled area)

among the regulations that are not issued under sections 161b, 161i, or

161o of the Atomic Energy Act, for purposes of section 223 of the Act.

On reconsideration, the Commission has decided not to revise this

section (i.e., criminal penalties are authorized for violations of

Sec. 60.136).

[[Page 64267]]

Small Business Regulatory Enforcement Fairness Act

In accordance with the Small Business Regulatory Enforcement

Fairness 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.

Environmental Impact: Categorical Exclusion

The NRC has determined that this regulation is the type of action

described in 10 CFR 51.22(c)(2), pertaining to the promulgation of

technical requirements and criteria that the Commission will apply in

approving or disapproving applications under part 60. Therefore,

neither an environmental impact statement nor an environmental

assessment has been prepared for this final rule.

Paperwork Reduction Act Statement

This final rule does not contain a new or amended information

collection requirement subject to the Paperwork Reduction Act of 1995

(44 U.S.C. 3501, et seq.). Existing requirements were approved by OMB,

approval number 3150-0127.

Public Protection Notification

The NRC may not conduct or sponsor, and a person is not required to

respond to, a collection of information unless it displays a currently

valid OMB control number.

Regulatory Analysis

The Commission has prepared a regulatory analysis on this final

rule. The analysis examines the costs and benefits of the alternatives

considered by the Commission. The analysis is available for inspection

in the NRC Public Document Room, 2120 L Street NW (Lower Level),

Washington, DC. Single copies of the analysis may be obtained from Dr.

Richard A. Weller, U.S. Nuclear Regulatory Commission, Office of

Nuclear Material Safety and Safeguards, Division of Waste Management,

Washington, DC 20555, Telephone (301) 415-7287.

Regulatory Flexibility Certification

As required by the Regulatory Flexibility Act of 1980, 5 U.S.C.

605(b), the Commission certifies that this rule will not have a

significant economic impact on a substantial number of small entities.

The only entity subject to regulation under this rule is DOE.

Backfit Analysis

The NRC has determined that the backfit rule, 10 CFR 50.109, does

not apply to this final rule and, therefore, that a backfit analysis is

not required for this final rule, because these amendments do not

involve any provisions that would impose backfits as defined in 10 CFR

50.109(a)(1).

List of Subjects in 10 CFR Part 60

Criminal penalties, High-level waste, Nuclear power plants and

reactors, Nuclear materials, Reporting and record-keeping requirements,

and 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 part 60.

PART 60--DISPOSAL OF HIGH-LEVEL RADIOACTIVE WASTES IN GEOLOGIC

REPOSITORIES

1. The authority citation for Part 60 is amended 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, 2228, as amended (42 U.S.C. 10134, 10141), and

Pub. L. 102-486, sec. 2902, 106 Stat. 3123 (42 U.S.C. 5851).

2. Section 60.2 is amended by adding definitions of ``Design

bases,'' ``Design basis events,'' and ``Preclosure controlled area,''

revising the definitions of ``Accessible environment,'' ``Disturbed

zone,'' ``Important to safety,'' ``Restricted area,'' ``Site,'' and

``Unrestricted area,'' revising the name of the defined term

``Controlled area'' to ``Postclosure controlled area'' and presenting

this renamed term without change for the convenience of the user, and

alphabetizing the definitions to read as follows:

Sec. 60.2 Definitions.

* * * * *

Accessible environment means:

(1) The atmosphere;

(2) The land surface;

(3) Surface water;

(4) Oceans; and

(5) The portion of the lithosphere that is outside the postclosure

controlled area.

* * * * *

Design bases means that information that identifies the specific

functions to be performed by a structure, system, or component of a

facility and the specific values or ranges of values chosen for

controlling parameters as reference bounds for design. These values may

be restraints derived from generally accepted ``state-of-the-art''

practices for achieving functional goals or requirements derived from

analysis (based on calculation or experiments) of the effects of a

postulated event under which a structure, system, or component must

meet its functional goals. The values for controlling parameters for

external events include:

(1) Estimates of severe natural events to be used for deriving

design bases that will be based on consideration of historical data on

the associated parameters, physical data, or analysis of upper limits

of the physical processes involved; and

(2) Estimates of severe external man-induced events, to be used for

deriving design bases, that will be based on analysis of human activity

in the region, taking into account the site characteristics and the

risks associated with the event.

Design basis events means:

(1)(i) Those natural and human-induced events that are reasonably

likely to occur regularly, moderately frequently, or one or more times

before permanent closure of the geologic repository operations area;

and

(ii) Other natural and man-induced events that are considered

unlikely, but sufficiently credible to warrant consideration, taking

into account the potential for significant radiological impacts on

public health and safety.

(2) The events described in paragraph (1)(i) of this definition are

referred to as ``Category 1'' design basis events. The events described

in paragraph (1)(ii) of this definition are referred to as ``Category

2'' design basis events.

* * * * *

Disturbed zone means that portion of the postclosure controlled

area, the physical or chemical properties of which have changed as a

result of underground facility construction or as a result of heat

generated by the emplaced radioactive wastes, such that the resultant

change of properties may have a significant effect on the performance

of the geologic repository.

* * * * *

Important to safety, with reference to structures, systems, and

components, means those engineered features of the repository whose

function is:

(1) To provide reasonable assurance that high-level waste can be

received,

[[Page 64268]]

handled, packaged, stored, emplaced, and retrieved without exceeding

the requirements of Sec. 60.111(a) for Category 1 design basis events;

or

(2) To prevent or mitigate Category 2 design basis events that

could result in doses equal to or greater than the values specified in

Sec. 60.136 to any individual located on or beyond any point on the

boundary of the preclosure controlled area.

* * * * *

Postclosure controlled area means a surface location, to be marked

by suitable monuments, extending horizontally no more than 10

kilometers in any direction from the outer boundary of the underground

facility, and the underlying subsurface, which area has been committed

to use as a geologic repository and from which incompatible activities

would be restricted following permanent closure.

Preclosure controlled area means that surface area surrounding the

geologic repository operations area for which the licensee exercises

authority over its use, in accordance with the provisions of this part,

until permanent closure has been completed.

* * * * *

Restricted area means an area, access to which is limited by the

licensee for the purpose of protecting individuals against undue risks

from exposure to radiation and radioactive materials. Restricted area

does not include areas used as residential quarters, but separate rooms

in a residential building may be set aside as a restricted area.

* * * * *

Site means the location of the preclosure controlled area, or of

the postclosure controlled area, or both.

* * * * *

Unrestricted area means an area, access to which is neither limited

nor controlled by the licensee.

* * * * *

3. Section 60.8 is revised to read as follows:

Sec. 60.8 Information Collection Requirements: Approval.

(a) The Nuclear Regulatory Commission has submitted the information

collection requirements of general applicability contained in this part

to the Office of Management and Budget for approval as required by the

Paperwork Reduction Act of 1995 (44 U.S.C. 3501, et seq.). The Office

of Management and Budget has approved the information collection

requirements contained in this part under control number 3150-0127.

(b) The approved information collection requirements contained in

this part appear in Secs. 60.62, 60.63, and 60.65.

4. In Sec. 60.21, paragraphs (c)(1)(i), (c)(1)(ii)(B), (c)(3), and

(c)(8) are revised to read as follows:

Sec. 60.21 Content of application.

* * * * *

(c) * * *

(1) * * *

(i) The description of the site shall also include the following

information regarding subsurface conditions. This description shall, in

all cases, include this information with respect to the postclosure

controlled area. In addition, where subsurface conditions outside the

postclosure controlled area may affect isolation within the postclosure

controlled area, the description shall include information with respect

to subsurface conditions outside the postclosure controlled area to the

extent the information is relevant and material. The detailed

information referred to in this paragraph shall include:

(A) The orientation, distribution, aperture in-filling and origin

of fractures, discontinuities, and heterogeneities;

(B) The presence and characteristics of other potential pathways

such as solution features, breccia pipes, or other potentially

permeable features;

(C) The geomechanical properties and conditions, including pore

pressure and ambient stress conditions;

(D) The hydrogeologic properties and conditions;

(E) The geochemical properties; and

(F) The anticipated response of the geomechanical, hydrogeologic,

and geochemical systems to the maximum design thermal loading, given

the pattern of fractures and other discontinuities and the heat

transfer properties of the rock mass and groundwater.

(ii) * * *

(B) Analyses to determine the degree to which each of the favorable

and potentially adverse conditions, if present, has been characterized,

and the extent to which it contributes to or detracts from isolation.

For the purpose of determining the presence of the potentially adverse

conditions, investigations shall extend from the surface to a depth

sufficient to determine critical pathways for radionuclide migration

from the underground facility to the accessible environment.

Potentially adverse conditions shall be investigated outside of the

postclosure controlled area if they affect isolation within the

postclosure controlled area.

* * * * *

(3) A description and analysis of the design and performance

requirements for structures, systems, and components of the geologic

repository that are important to safety. The analysis must include a

demonstration that--

(i) The requirements of Sec. 60.111(a) will be met, assuming

occurrence of Category 1 design basis events; and

(ii) The requirements of Sec. 60.136 will be met, assuming

occurrence of Category 2 design basis events.

* * * * *

(8) A description of the controls that the applicant will apply to

restrict access and to regulate land use at the site and adjacent

areas, including a conceptual design of monuments which would be used

to identify the postclosure controlled area after permanent closure.

* * * * *

Sec. 60.43 [Amended]

5. In Sec. 60.43(b)(5), the term ``controlled area'' is revised to

read ``postclosure controlled area.''

Sec. 60.46 [Amended]

6. In Sec. 60.46(a)(3), the term ``controlled area'' is revised to

read ``postclosure controlled area.''

Sec. 60.51 [Amended]

7. In Sec. 60.51(a)(2)(i) and (a)(2)(ii), the term ``controlled

area'' is revised to read ``postclosure controlled area.''

Sec. 60.102 [Amended]

8. In Sec. 60.102(c), the term ``controlled area'' is revised to

read ``postclosure controlled area.''

9. In Sec. 60.111, paragraph (a) is revised to read as follows:

Sec. 60.111 Performance of the geologic repository operations area

through permanent closure.

(a) Protection against radiation exposures and releases of

radioactive material. The geologic repository operations area shall be

designed so that until permanent closure has been completed, radiation

exposures and radiation levels, and releases of radioactive materials

to unrestricted areas, will be maintained within the limits specified

in part 20 of this chapter and such generally applicable environmental

standards for radioactivity as may have been established by

Environmental Protection Agency.

* * * * *

Sec. 60.121 [Amended]

10. In Sec. 60.121(a) and (b), the term ``controlled area'' is

revised to read ``postclosure controlled area.''

[[Page 64269]]

Sec. 60.122 [Amended]

11. In Sec. 60.122(b)(6) and (c) introductory text, the term

``controlled area'' is revised to read ``postclosure controlled area.''

12. Section 60.130 is revised to read as follows:

Sec. 60.130 General considerations.

Pursuant to the provisions of Sec. 60.21(c)(2)(i), an application

to receive, possess, store, and dispose of high-level radioactive waste

in the geologic repository operations area must include the principal

design criteria for a proposed facility. The principal design criteria

establish the necessary design, fabrication, construction, testing,

maintenance, and performance requirements for structures, systems, and

components important to safety and/or important to waste isolation.

Sections 60.131 through 60.134 specify minimum requirements for the

principal design criteria for the geologic repository operations area.

These design criteria are not intended to be exhaustive. However,

omissions in Secs. 60.131 through 60.134 do not relieve DOE from any

obligation to provide such features in a specific facility needed to

achieve the performance objectives.

13. In Sec. 60.131, paragraph (b) is revised, and paragraphs (c)

through (k) are added to read as follows:

Sec. 60.131 General design criteria for the geologic repository

operations area.

* * * * *

(b) Protection against design basis events. The structures,

systems, and components important to safety shall be designed so that

they will perform their necessary safety functions, assuming occurrence

of design basis events.

(c) Protection against dynamic effects of equipment failure and

similar events. The structures, systems, and components important to

safety shall be designed to withstand dynamic effects such as missile

impacts, that could result from equipment failure, and similar events

and conditions that could lead to loss of their safety functions.

(d) Protection against fires and explosions. (1) The structures,

systems, and components important to safety shall be designed to

perform their safety functions during and after credible fires or

explosions in the geologic repository operations area.

(2) To the extent practicable, the geologic repository operations

area shall be designed to incorporate the use of noncombustible and

heat resistant materials.

(3) The geologic repository operations area shall be designed to

include explosion and fire detection alarm systems and appropriate

suppression systems with sufficient capacity and capability to reduce

the adverse effects of fires and explosions on structures, systems, and

components important to safety.

(4) The geologic repository operations area shall be designed to

include means to protect systems, structures, and components important

to safety against the adverse effects of either the operation or

failure of the fire suppression systems.

(e) Emergency capability. (1) The structures, systems, and

components important to safety shall be designed to maintain control of

radioactive waste and radioactive effluents, and permit prompt

termination of operations and evacuation of personnel during an

emergency.

(2) The geologic repository operations area shall be designed to

include onsite facilities and services that ensure a safe and timely

response to emergency conditions and that facilitate the use of

available offsite services (such as fire, police, medical, and

ambulance service) that may aid in recovery from emergencies.

(f) Utility services. (1) Each utility service system that is

important to safety shall be designed so that essential safety

functions can be performed, assuming occurrence of the design basis

events.

(2) The utility services important to safety shall include

redundant systems to the extent necessary to maintain, with adequate

capacity, the ability to perform their safety functions.

(3) Provisions shall be made so that, if there is a loss of the

primary electric power source or circuit, reliable and timely emergency

power can be provided to instruments, utility service systems, and

operating systems, including alarm systems, important to safety.

(g) Inspection, testing, and maintenance. The structures, systems,

and components important to safety shall be designed to permit periodic

inspection, testing, and maintenance, as necessary, to ensure their

continued functioning and readiness.

(h) Criticality control. All systems for processing, transporting,

handling, storage, retrieval, emplacement, and isolation of radioactive

waste shall be designed to ensure that nuclear criticality is not

possible unless at least two unlikely, independent, and concurrent or

sequential changes have occurred in the conditions essential to nuclear

criticality safety. Each system must be designed for criticality safety

assuming occurrence of design basis events. The calculated effective

multiplication factor (keff) must be sufficiently below unity to

show at least a 5 percent margin, after allowance for the bias in the

method of calculation and the uncertainty in the experiments used to

validate the method of calculation.

(i) Instrumentation and control systems. The design shall include

provisions for instrumentation and control systems to monitor and

control the behavior of systems important to safety, assuming

occurrence of design basis events.

(j) Compliance with mining regulations. To the extent that DOE is

not subject to the Federal Mine Safety and Health Act of 1977, as to

the construction and operation of the geologic repository operations

area, the design of the geologic repository operations area shall

nevertheless include provisions for worker protection necessary to

provide reasonable assurance that all structures, systems, and

components important to safety can perform their intended functions.

Any deviation from relevant design requirements in 30 CFR, chapter I,

subchapters D, E, and N will give rise to a rebuttable presumption that

this requirement has not been met.

(k) Shaft conveyances used in radioactive waste handling. (1)

Hoists important to safety shall be designed to preclude cage free

fall.

(2) Hoists important to safety shall be designed with a reliable

cage location system.

(3) Loading and unloading systems for hoists important to safety

shall be designed with a reliable system of interlocks that will fail

safely upon malfunction.

(4) Hoists important to safety shall be designed to include two

independent indicators to indicate when waste packages are in place and

ready for transfer.

14. In Sec. 60.132, paragraph (c)(1) is revised to read as follows:

Sec. 60.132 Additional design criteria for surface facilities in the

geologic repository operations area.

* * * * *

(c) Radiation control and monitoring--(1) Effluent control. The

surface facilities shall be designed to control the release of

radioactive materials in effluents during Category 1 design basis

events so as to meet the performance objectives of Sec. 60.111(a).

* * * * *

15. In Sec. 60.133, the introductory texts of paragraph (g) and

paragraph (g)(2) are revised to read as follows:

[[Page 64270]]

Sec. 60.133 Additional design criteria for the underground facility.

* * * * *

(g) Underground facility ventilation. The ventilation system shall

be designed to:

* * * * *

(2) Assure the ability to perform essential safety functions

assuming occurrence of design basis events.

* * * * *

16. A new undesignated center heading and Sec. 60.136 are added to

read as follows:

Preclosure Controlled Area

Sec. 60.136 Preclosure controlled area.

(a) A preclosure controlled area must be established for the

geologic repository operations area.

(b) The geologic repository operations area shall be designed so

that, for Category 2 design basis events, no individual located on or

beyond any point on the boundary of the preclosure controlled area will

receive the more limiting of a total effective dose equivalent of 0.05

Sv (5 rem), or the sum of the deep-dose equivalent and the committed

dose equivalent to any individual organ or tissue (other than the lens

of the eye) of 0.5 Sv (50 rem). The eye dose equivalent shall not

exceed 0.15 Sv (15 rem), and the shallow dose equivalent to skin shall

not exceed 0.5 Sv (50 rem). The minimum distance from the surface

facilities in the geologic repository operations area to the boundary

of the preclosure controlled area must be at least 100 meters.

(c) The preclosure controlled area may be traversed by a highway,

railroad, or waterway, so long as appropriate and effective

arrangements are made to control traffic and to protect public health

and safety.

Dated in Rockville, Maryland, this 25th day of November, 1996.

For the Nuclear Regulatory Commission.

John C. Hoyle,

Secretary of the Commission.

[FR Doc. 96-30710 Filed 12-3-96; 8:45 am]

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