ML20199K442

Comments on Indian Point Special Proceeding.Severe Accident Policy Statement Should Be Reexamined

ML20199K442
Person / Time
Site:	Indian Point
Issue date:	05/10/1986
From:	Okrent D Advisory Committee on Reactor Safeguards
To:	Palladino N NRC COMMISSION (OCM)
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ML20199K429	List: ML20199K424 ML20199K442
References
NUDOCS 8607090156
Download: ML20199K442 (2)

Text

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t May 10, 1986 l

- l Honorable Nunzio J. Palladino i Chairman .- i U.S. Nuclear Regulatory Commission -

Washington, D.C. 20555 l

SUBJECT:

INDIAN POINT SPECIAL PROCEEDING I would like to thank you and the other Comissioners for your thought-  ;

ful response to the letter dated October 12, 1985 from five ACRS members concerning Indian Point. I am sorry that my memory was faulty with regard to a few specific details of the testimony and positions. From among the many pages of testimony, etc., I must have had in mind SECY-85-100, dated March 19, 1985 from M. Malsch, 0GC, and J. Zerbe, OPE, to the Comission, in which it says, "The licensees also agreed with Judge Gleason's dissent, arguing that, despite the low level of risk, the Board majority had overemphasized the need for risk-reducing measures, such as a filtered vented containment." No matter. That was not and is not the issue.

The Commission appears to have hinged its decision primarily on whether Indian Point was a risk outlier, 'i.e., in a high-risk class all its own.

This issue certainly received prominence in the proceedings; however, I question that it should be the sole or even principal basis for long-term decision making on severe accident or safety goal policy for Indian Point.

A growing number of nuclear power plants is receiving PRA results ,

yielding core melt frequencies well above ten to the minus four per reactor-year. As you know, the ACRS has now stated in three letters to the Comission its ' belief that a mean-core-melt frequency of less than (or not more than) ten to the minus four per reactor-year should be an NRC objective for all but a few, small existing nuclear power plants.

There clearly will be considerable uncertainty in the estimate of core melt frequency made for any specific reactor. It seems to me that one way of bringing population density into decision making is to ask that this guideline be met with greater confidence for the more densely populated sites. This would provide still greater impetus to the recomendation made by five ACRS members in their letter of October 12, 1985.

In its letter of April 15, 1986 providing additional coments on pro-posed safety goal policy, the ACRS also recommended a second quantita-l tive performance guideline, one related to containment performance such that the chance of a very large release from containment should be less 8607090156 860627 PDR COMMS NRCC CORRESPONDENCE PDR

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Honorable Nunzio J. Palladino May 10, 1986 than ten to the minus six per reactor-year. I think it is fair to guess that the ASLB majority would favor increased confidence that some such guideline be met at Indian Point. Incidentally, I bel.ieve that the analysis of matters affecting containment performance in the Indian Point probabilistic risk assessment included both generic and plant-specific factors.

It is for reasons such as these that I question the Commission decision on Indian Point as being appropriate for the long term. Many countries are implementing safety improvements in a disciplined fashion for nuclear power reactors whose risk estimates do not make them risk outliers. I wish to suggest that U.S. policy on nuclear reactor safety at least give serious reconsideration to the overall merit of achieving still greater confidence in a low likelihood of core melt and a very low likelihood of a major release of radioactive material, particularly at densely populated sites.

I should like to observe that it may be awkward to judge whether the Comission decision on Indian Point is consistent with the ACRS comments of July 18, 1984 on severe accident policy. The ACRS letter is not definitive on how "to take into account the results of programs now in progress." I myself find disquieting the results obtained from evalua-tion of containment performance for the BWR Mark I. I also gain little solace from the considerable number of PRAs yielding core melt fre-quencies well above ten to the minus four per reactor year. As I stated in additional comments to the July 18, 1984 letter, I think there is reason to reexamine the relatively optimistic flavor of the Severe Accident Policy Statement. What adds to the problem is the general impression now being given to much of the Americar, public that U.S.

power reactors have containment structures that can be expected to prevent any large-scale release of radioactivity, given the occurrence of a large-scale core melt accident.

In any event, I wish to thank you for your untiring efforts as Chairman of the NRC and to wish you well.

Sincerely, w

David Okrent cc:

Commissioner Roberts Commissioner Asselstine Commissioner Bernthal Commissioner Zech Other Members of ACRS

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