ML20236V790

Comments on Proposed Commission Paper on Implementation of Severe Accident Policy for Future Nuclear Power Plant Applications,Per 871106 Request.Paper Does Not Contain Adequate Analysis for Any of Three Proposed Rules

ML20236V790
Person / Time
Issue date:	11/19/1987
From:	Houston R NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
To:	Morris B NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
Shared Package
ML20236V745	List: ML20236V743 ML20236V790
References
NUDOCS 8712070098
Download: ML20236V790 (3)

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'UmTED STATES

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NUCLEAR REGULATORY COMMISSION -

w AsmNG TON, D. C. 20555 k...l. [l' November 19, 1987

. MEMORANDUM FOR: : B. M. Morris, Director Division of Regulatory Applications 7

FROM:

R. W. Houston, Acting Director; Division of Reactor Accident Analysis y

SUBJECT:

PROPOSED COMMISSION PAPER ON' IMPLEMENTATION OF. SEVERE ACCIDENT POLICY FOR FUTURE NUCLEAR POWER PLANT' APPLICATIONS You requested coments on the subject paper in your n.emorandum dated November 6, 1987.

This most recent revision continues.to reflect the'same.

approach-to dealing'with severe accident ~ issues on future plants that we :found

.in all of.the previous versions. As you are quite aware, I do not. concur in this approach for a variety.of reasons.

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. First, the' Severe Accident Policy Statement itself articulates quite clearly the.s'et of criteria thatLthe' Commission' expects to be applied to future plants.

In particular, it did not direct the. staff >to' undertake rulemaking activities' to; achieve'the. general objectives for' future plants. Notwithstanding this, it

'is.not necessarily; inappropriate for~ the. staff to recommend' rulemaking, but, at the-very least. such recommendations should be justified _and presented to the

.Comission as-a recommended alternative among options considered.

I do no find that this pape contains adequate analysis in this respect for any of he three' proposed rules.

One of the stated purposes of the proposal is "to codify severe accident requirements. prior to initiation'of design certification.rulemaking on standard plant applications." To the best of my knowledge...there is no current user request from NRR in this direction'and I believe we'are still waiting for NRR views based upon an earlier proposed version of-this paper. Meanwhile, as you are aware,'there are already three-standard LWR design applications in-house and available evidence seems to show quite clearly that each of these appli-cations incorporates plans to address the criteria set forth in the Severe Accident Policy Statement, even though there is no explicit regulation that would. require them to do so.

Indeed, the NRC staff has already demonstrated

that it is feasible to deal with severe accident issues in the context of the

'GESSAR 11 standard design although admittedly, the adequacy of that review was not tested in the context of a hearin certification by rulemaking process. g process such as is likely to occur in e i

With respect to this latter process, I believe there is a legitimate question j

i as to whether or not the criteria articulated only in the Severe Accident Policy Statement is an adequate basis for dealing with severe accident issues in an associated hearing.

The advice of OGC on this question is clearly warranted end should be a priority consideration in any proposed rulemaking

'that would be applicable to nroposed standard plant designs.

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specific. issues here relate to the critsria in 10CFR50.34(f), the USI/GS!

resolutions,' and the PRA. Your currently proposed paper is silent on both;of L l

the'former,although I would guess that you may envision that these could~ be 3

dealt withlin1the context of. the. two proposed Regulatory Guides..

SWith. respect'to.the PRA' issue, I note the'proposedirevision of.10CFR50.34.

I-find it curious thatlthe word "probabilistic" is not'in'the title of' thel

, proposed 50.34(h),1and that the wording would not make the rule applicable-5' directly: to vendor appl.ications. for standard designs..(The same can be said

, Labout the implementation statements; for the proposed Regulatory, Guides.)1 The.

. Severe? Accident Policy Statement criteria.for future plants;made reference to:

thel existing CP/ML rule.._10CFR50.34(f), that set forth a set of' specific-

- requirements.for the then: active.CP and ML applications, erisihg 'from the TMI accident.. Depending upon how:one coes the counting, there are at least 46'-

separate. and~ distinct requirements identified in ~ this rule,' only one of-which

~6cdresses a PRA.- It would seem that'at least some explanation or consideration

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' of;the other 45 items is warranted.

~ The titie.of. the proposed paper includes the words. Safety Coals and the text Lappears to propose ~~ar loose definition of f the tenn "large release" as used in

the. general performance guideline proposed by the Comission when it published 4

the1 Safety Goal Policy Statement in Augupt 1986. As I believe you are aware we,

'are in the. process of developing a. revised implementation plan for Safety Goals-i and interacting with the ACRS.on it. A recent SRM from the'0ffice of the

. Secretary hasL f ndicated a concurrence by the Comission on ACRS views on Safety -

Goal: implementation. Among other. things, the ACRS pcsition is that the SafeJy Goal objectives shoul'd be used to assess.the adecuacy of regulations and

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regulatory practices rather than for. " narrowly differentiated decisions about -

specific plants."

The Commission. guidance to the' staff does, however, provide the caveat that i

'"if Information is developed that is applicable to a.particular licensing.

decision, the Commission endorses consideration of"that information as a factor in the licensing decision." This statement is intended to be read in the

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context of information derived from the performance and/or review of a PRA.

i Neither the'ACRS nor the Commission guidance makes'any distinction between j..

present' and future plants on this' point and this is still a matter to be

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' discussed more thoroughly with the ACRS, i.e., whether Safety Goal objectives o

for future plants should be different from those for present plants, given the Commission's expressed expectations that "the vendors engaged in designino new standard (or custom) ' plants will achieve a higher standard of severe accident

' safety performance than their prior designs."

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What this all means to me is that we have yet to attain staff, ACRS, and Comission concurrence on quantitative objectives or targets for new and j

existing plants, but more importantly, in the context of the propostio

^ Comission paper that,if new rules are to be sdopted for future plants, they

.may' derive from and have a basis in Safety Coal considerations and information derived from PRA, but should not be cast in a fonn of the objectives I

.themselves. More specifically, for example, if existing General Design Critoria"are believed to be inadequate in the light nf severe acticent rist and y.

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' S'afety Goal considerations,-then one should consider their' potential.

replacement by new criteria as a design basis,. articulated in deterministic fashion so that there can be little doubt on.the part.of designers, for

example, as to how' to design'an acceptable containment. : The general thrust of--

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3' the-two proposed ~new General Design criteria, in my view,'do not achieve this.

but rather,: leave;open the opportunity for endless debate as to the precision

,or accuracy w ti h which probabilistically framed criteria lare or ever can be-known. 'In brief, such debate should be relegated to the rulemaking-process, q;

i not'thel licensing process.

In' this rather lengthy coment memorandum. I am trying.to be constructive.

I-rules and Regulatory Guides to the present standard plant appif/y the pro don't'believe that the specific goal you have set, i.e., to appl ations can be accomplished in a, time frame commensurate with the current schddules. What.I

-believe can,'and must be done in that time frame, is to accomplish the task set-

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by the Commission in the Severe Accident Policy Statement to:" issue guidance on a

the. form, purpose, and role that PRAs are to play in severe accident. analysis

- and. decision making:for both existing and future plant designs' and what minimum criteria of adequacy PRAsishould meet." Although, there is merit to some of

<- the material we have.seen in. Draft NUREG/CR-4812, which I'believe was prepared to accomplish'this. task, major revisions-are necessary, including the necessi.ty-of: transforming it into some different kind of staff document; perhaps an

interim Regulatory Guide. As I have indicated in prior correspondence I

.believe this Division (DRAA) isiin the best position to.do this in conjunction with'our ongoing effort to prepare PRA review guidance.

If believe other more _ specific coments on the proposed Comission' Paper have-

been transmitted to you informally reflecting some views of Jerry Hulman an[

Joe Murphy.

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Uw R.W. Houston,'AhtingDirector Division of Reactor Accident Analysis cc:

E. Beckjord T. Speis G. Arlotto B. Sherun l'

J. Murphy

'L. Hulman l-F.'Miraglia - NRR D. Crutchfield - NRR 1

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