ML20138F090

Presents ACRS Position on Indian Point Special Proceeding. Schedule & Plan Development Recommended to Reduce Estimated Core Melt Frequency & Uncertainty.Detailed Containment Performance Evaluation for Particular Sites Suggested

ML20138F090
Person / Time
Site:	Indian Point
Issue date:	10/12/1985
From:	Okrent D Advisory Committee on Reactor Safeguards
To:	Palladino N NRC COMMISSION (OCM)
References
NUDOCS 8510250179
Download: ML20138F090 (3)

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G October 12, 1985 v'3

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Honorable Nunzio J. Palladino

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i Chairman U. S. Nuclear Regulatory Comission Washington, D. C. 20555

Subject:

INDIAN POINT SPECIAL PROCEEDING

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We recognize that the Comission has acted on the Indian Point Special.

Proceeding but believe that it is worthwhile to provide some coments and recomendations for your further reflection.

We shall not go into i

details of the proceeding but deal only with relatively broad consid-erations, as follows:

1.

Mr. Rowsome of the NRC Staff testified that Indian P,gint. Unit 2 has a median frequency of core melt cf roughly 4 x 10 per reactor i

year for the "after fix" staff analysis described in the NRC testimony on Comission Question One, with a similar result for Indian Point, Unit 3.

If this value were approximately represen-tative of the U. S. light water power reactors, it would suggest a chance of about one in two of a core melt accident by the year 2000 and a likelihood of essentially unity over the life of the current LWRs.

The uncertainties in the estimate for. Indian point are clearly l

large, with some factors pointing to possible overestimate and

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others to underestimate.

l, We believe.that, especially for a high power nuclear power plant at one of the most highly populated sites in the U. S., the NRC should continue to strive for a substantial reduction in both the pre-dicted core melt frequency and the uncertainty therein.

Indian Point Units 2 and 3 are evaluated by the Licensee and the NRC Staff as having a relatively effective containment in the i

l presence of many, if not most, severe core accidents.

However.

l these analyses rest on incompletely understood phenomena,(and on l

generic rather than detailed examinations of containment Plant) behavior, and on an incomplete set of accident scenarios.

l Mr. Rowsome stated that he would be only mildly surprised if the

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consequences were a factor of 40 higher (or 200 lower) than the NRC Staff estimates.

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Honorable Nunzio J. Palladino *

'The NRC Staff did not recomend design or operational improvements 2.

j for the Indian Point units except for a reliability assurance program.

However, they stated that, "it is the ensemble of evi-dence and the continued use of the PRA as a risk management tool (the safety assurance program).

that supported the s.taff recomendations." The majority of the ASLB recomended in favor of a filtered venting concept in view of the large uncertainties in the risk assessment and the high surrounding population density.

The Comission itself took a position less conservative than either the Staff or the majority of the ASLB.

3.

Since the Staff testimony at the Indian Point hearings, senior members of the NRC Staff have written coments in connection with consideration of the NRC Safety Goals which are possibly at odds with the Indian Point decision.

The Safety Goal Task Force, which includes Messrs. Murley, Rowsome, and Ernst, among others, raised

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the core melt fre and Mr. Minogue, quency objective to first line status. Mr. Ernst in memoranda of May 10, 1985 and May 21 j

bdth support working toward the core melt safety goal of 10'J985, per reactor year for existing nuclear power plants. Mr. Denton, in his memorandum of June 12, 1985, melt goal for existing plants.recomends a still more stringent core 4.

In its report to you af July 17, 1985, the ACRS expressed its belief, "that the Comission ghould state that a mean-core-melt frequency of not more than 10' per reactor year is an NRC objec-tive for all but a few, small, existing nuclear plants, and that, keeping in mind the considerable uncertainties, prudence and judgment will tend to take priority over benefit-cost analysis in working toward this goal."

5.

We strongly support this ACRS position, and y believe that a median estimate core melt frequency of 4 x 10 per reactor year (with very large uncertainties), for a high power plant at one of' the most densely populated sites in the U. S., is too large for the long tenn and represents a situation requiring specific attention.

While we agree that it is acceptable for Indian Point. Units 2 and that both the Licensee an,d the NRC Staff develop, on som able schedule, a plan for work intended to reduce both the esti-mated core melt frequency and the uncertainty therein.

In addi-tion, we believe that detailed containment performance evaluation should be given particular emphasis at sites like Indian Point.

It is our belief that Comission policy should reflect prudence and come down on the side of safety, where the uncertainties remain large, giving appropriate consideration to both prevention and

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4 Honorable Nunzio J. Palladino,

mitigation.

We believe that, particularly if innovative approaches are used, significant improvements in safety are achievable for Indian Point. Units 2 and 3, at reasonable costs.

Sincerely.

Eavid Okrent, University of california Los Angeles, California I

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pAuthority, retired, Knoxville, Tennessee se

. E >ersole. Tennessee Valley a

r Dade W. Moeller, Harvard Un' verstty Boston, Massachusetts

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____4 Elenn A. Reed, W'scons' n Electric Power Company, Retired, Two Rivers.

Wisconsin d

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01arles J. Ky(ieV, uke r company, j

Retired, Cha?ftrfte, rolina I

cc: Comissioner Roberts Comissioner Asselstine Comissioner Bernthal Comissioner Zech Other Members of the Advisory Comittee on Reactor Safeguards i

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