[Federal Register Volume 61, Number 234 (Wednesday, December 4, 1996)]
[Rules and Regulations]
[Pages 64257-64270]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-30710]
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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
[[Page 64261]]
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]
BILLING CODE 7590-01-P
