[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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