[Federal Register Volume 62, Number 198 (Tuesday, October 14, 1997)]
[Proposed Rules]
[Pages 53250-53251]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-27082]
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NUCLEAR REGULATORY COMMISSION
10 CFR Part 50
RIN 3150-AE38
Acceptability of Plant Performance for Severe Accidents; Scope of
Consideration in Safety Regulations
AGENCY: Nuclear Regulatory Commission.
ACTION: Advance notice of proposed rulemaking: Withdrawal.
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SUMMARY: The Nuclear Regulatory Commission (NRC or Commission) is
withdrawing an advance notice of proposed rulemaking that outlined
alternative approaches to generic regulation addressing the challenges
from severe accidents for future light water reactors. The Commission
has decided that a rule change to provide generic requirements for
performance during postulated severe accidents is not warranted at this
time. The basis for this decision is that a purpose for the rule was to
provide guidance for future designs and to facilitate then ongoing
design certification rulemaking. With all current design certification
rulemaking either complete or nearing completion and future applicants
not foreseen, expenditure of the resources to promulgate the rule is
not warranted.
FOR FURTHER INFORMATION CONTACT: Charles E. Ader, Office of Nuclear
Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC
20555-0001, telephone (301) 415-5622.
SUPPLEMENTARY INFORMATION: On September 28, 1992, (57 FR 44513), the
Commission published an advance notice of proposed rulemaking (ANPRM)
to consider amending its regulations to provide generic requirements to
address the challenges from severe accidents for future light water
reactors. The advance notice of proposed rulemaking outlined three
alternative approaches to the specification of requirements addressing
severe accident performance. The first alternative, described as a
hardware oriented rule, would specify reasonable design features or
design characteristics directed towards prevention or mitigation of
explicitly identified risk significant phenomena. The risk significant
phenomena identified were: hydrogen generation, transport and
combustion, high pressure melt ejection, core concrete interactions and
basemat ablation, long term containment overpressurization, steam
explosions from fuel-coolant interactions, and containment bypass.
These phenomena represent the potential contributors to containment
failure or bypass and thus the mechanisms for large offsite radioactive
release. Alternative 2, described as a phenomena oriented rule, was a
modification of the first alternative wherein an overall containment
performance goal would be specified along with the phenomena to be
considered, as identified above. The designer would then be required to
perform analyses of the impact of those phenomena and develop and
propose the design features to meet the goal. Regulatory guides would
address analytical methods, acceptance criteria and design criteria for
hardware. This approach, similar to Alternative 1, would be an overlay
on the existing design basis specified in 10 CFR part 50 and justified
on an enhanced safety basis. The third alternative, described as a
general design criteria (GDC) oriented rule, involved development of a
set of new design requirements to address specific challenges and
issued as changes to Appendix A, ``General Design Criteria'' to 10 CFR
part 50. Each new design criterion would describe the nature of the
challenges as well as the success criterion and involve the development
of Regulatory Guides to provide additional guidance on analysis methods
and assumption. This approach was similar to the other alternatives,
especially Alternative 2, but differs in that the existing 10 CFR part
50 design basis would be modified to include severe accidents.
A primary purpose for the generic severe accident rulemaking was to
add consistency and standardization to the resolution of severe
accident issues for future designs based on current technical
information. While, in general, consistency among many design reviews
is best achieved through generic rules, as a practical matter, since
the number of new applicants is likely to remain quite limited, it is
more efficient to proceed with design-specific reviews. In fact, the
Commission is not aware of any new applicants in the foreseeable
future.
[[Page 53251]]
Another purpose of the generic severe accident rulemaking, i.e.,
facilitation of design certification rulemaking, has been rendered moot
by the experience gained in design certification rulemakings. The
design certification rulemakings are completed for the General Electric
Advanced Boiling Water Reactor and ABB-CE System 80+ and the only
design currently under review is the Westinghouse AP600. The resolution
of severe accident design specific requirements would be set forth in
the AP600 design control document and approved in the AP600 design
certification rulemaking.
While certain arguments in favor of generic rulemaking (i.e.,
promoting consistency and standardization in the resolution of severe
accident issues and providing guidance to future LWR designers and
applicants) continue to apply in varying degrees, practical aspects
limit the need for such an activity. At this point, given the lack of
any new potential plant or design applicants, the Commission believes
that the benefits of generic rulemaking do not justify the allocation
of resources to proceed with the development of new regulations
addressing severe accidents.
Upon consideration of the potential value of a generic rule, the
status of the review and design certification of future reactors, and
the potential resource requirements, the Commission believes that the
value in pursuing generic severe accident rulemaking does not warrant
the resource expenditure. While the Commission does not perceive the
need for generic rulemaking in the foreseeable future, should
conditions change regarding potential applicants, the Commission would
reassess the merits of rulemaking at that time.
For the reasons discussed, the Commission is withdrawing the ANPRM.
Dated at Rockville, Md. this 7th day of October, 1997.
For the Nuclear Regulatory Commission.
John C. Hoyle,
Secretary of the Commission.
[FR Doc. 97-27082 Filed 10-10-97; 8:45 am]
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