ML20197E816

Provides Conclusions & Recommendations Re Proposed Final Regulatory Guide 1.174 & Standard Review Plan Chapter 19 for risk-informed,performance-based Regulation,Which Was Reviewed During 446th & 447th Meetings of ACRS

ML20197E816
Person / Time
Issue date:	12/11/1997
From:	Seale R Advisory Committee on Reactor Safeguards
To:	Shirley Ann Jackson, The Chairman NRC COMMISSION (OCM)
References
RTR-REGGD-01.174, RTR-REGGD-1.174 ACRS-R-1737, FACA, NUDOCS 9712300083
Download: ML20197E816 (3)

Text

'o,,

- UNITED STATES

.I NUCLEAR RECULATORY COMMISSION ACRSR-1737 n

{

I ADVISORY COMMITTEE ON REACTCO SAFECUARDS PDR o,

,I WASHINGTON. C. C. 205M

',%,,,,, /

December 11. 1997 f

The Honorable Shirley Ar.n Jackson Chairman U.S. Nuclear Regulatory Comission Washington, D.C. 20555-0001

SUBJECT:

PROPOSED FINAL REGULATORY GUIDE 1.174 AND STANDARD REVIEW PLAN CHAPTER 19 FOR RISK-INFORMED. PERFORMANCE-BASED cfSULATION During the 446th and 447th meetings of the Advisory Comittee on Reactor Safeguards. November 6-7 and December 3 6. 1997. respectively, we met with representatives of the NRC staff to review proposed final Regulatory Guide 1.174.

"An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plaat-Specific Changes to the Current Licensing Basis." and Standard Review Plan (SRP) Chapter 19 (General Guidance) for risk-informed, performance based regulation.

We discussed the staff's reconciliation of public comments on the subject documents, including proposed changes to address policy issues under consideration by the Comission.

Our Subcomittee on Reliability end Probabilistic Risk Assessment (PRA) met with the staff and industry representatives on October 21-22 and November 12-13. 1997, to discuss these matters. We also had the benefit of the documents referenced.

Conclusions ard Recommendations 1.

We recomend that Regulatory Guide 1.174 and associated Standard Review Plan Chapter 19 be approved and issued for use by the industry and staff.

2.

The modification of the acceptance guidelines to allow consideration of very small increases in CDF (core damage frequency) and LERF (large, early release frequency) fc.~ = broader range of the total CDF or LERF values is appropriate.

3.

The decisionmaking process described in Regulatory Guide 1.174 and. in particular its treatment of quantified and unquantified uncertainties, is sound.

The staff has correctly focused on identify 1 rig the important sources of uncertainty and determining their impact on decisions, rather

\\

MO I O

^

23 3 771211

~

CW/ MES R-1737 PDR l

_y

, a r-gn

t

=2*

than simply using the final distribution as the sole basis for decisionmaking.

4.

The staff discussion of PRA quality in these oo:uments is appropriate. We agree with the staff position that the assessment of the scope and quality of the probabilistic analyses should focus on whether they are adequate for the purpose intended, As we stated in our report dated March 17,1997, we believe that this new process and these documents are a significant achievement that will contripute to the safe and efficient use of nuclear power.

We believe that these documents will evolve as experience is gained. We again urge the staff to seek innovative applications of the risk-informed approach to regulation so that this Regulatory Guide and the associated Standard Review Plan Chapter will be teste% and improved upon in practice.

We request the staff to brief the Comittee periodically on this regulatory activity.

Sincerely,

f. W, - r

-4 4

R. L. Seale Chairman References

• 1.

Memorandum dated November 24, 1997, from M. Wayne Hodges. Office of Nuclear Regulatory Research, NRC. and Gary H. Holahan, Office of Nuclear Reactor Regulation, NRC, to John Larkins, ACRS.

Subject:

" General Regulatory Guide (DG 1061) and Standard Review Plan (SRP Chapter 19) for Risk Informed Regulatory Decisionmaking for Plant Specific Ci.B Changes."

with attachments, as follows:

Proposed Final Regulatory Guide 1.174 (Draft Guide DG 1061; cated November 25, 1997. "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant Specific Changes to the Current Licensing Basis."

Pr@osed Final Standard Review Plan Chapter 19 Revision N, dated November 25, 1997 "Use of Probabilistic Risk Assessment in Plant-Specific, Risk-Informed Decisionmaking: General Guidance."

i 3

4,.

2.,

Draft SECY dated November 7,1997, from L.

Joseph Callan, Executive Direr. tor for Operations, NRC, for the Comissioners, " Final Regulatory Guidance on Risk Informed Regulation: Policy Issues.*

._.-