ML20217A890

Summary of ACRS Reliability & PRA 971021-22 Meeting in Rockville,Md Re Matter Included in Staff Requirements Memo,

ML20217A890
Person / Time
Issue date:	11/21/1997
From:	Apostolakis G Advisory Committee on Reactor Safeguards
To:	Advisory Committee on Reactor Safeguards
References
ACRS-3077, NUDOCS 9803250293
Download: ML20217A890 (10)

Text

CERTIFIED BY: Date Issued: 11/21/97 George Apostolakis - 12/6/ J ADVISORY COMMITTEE ON REACTOR SAFEGUARDS MEETING OF THE SUBCOMMITTEE ON RELIABILITY AND PROBABILISTIC RISK ASSESSMENT MEETING MINUTES - OCTOBER 21-22, 1997 ROCKVILLE, MARYLAND INTRODUCTION The ACRS Subcommittee on Reliability and Probabilistic Risk Assessment (PRA) met on October 21-22, 1997, at 11545 Rockville Pike, Rockville, MD , in Room T-2B3. The purpose of this meeting was to continue the Subcommittee's review of the matter included in the Staff Requirements Memorandum dated May 27, 1997, regarding the use of uncertainty versus point values in the PRA-related decisionmaking process. The Subcommittee also reviewed the public comments and the expected changes to the proposed Standard Review Plan (SRP) sections and associated Regulatory Guides for risk-informed, performance-based regulation.

The entire meeting was open to public attendance. Mr. Michael T.

Markley was the cognizant ACRS staff engineer for this meeting.

The meeting was convened at 8:30 a.m. each day and recessed at 3:45 p.m. on October 21 and adjourned at 11:00 a.m. on October 22, 1997.

ATTENDEES ACRS G. Apostolakis, Chairman R. Seale, Member J. Barton, Member W. Shack, Member M. Fontana, Member R. Sherry, ACRS Fellow T. Kress, Member M. Markley, ACRS Staff D. Miller, Member NRC Staff M. Caruso, NRR* R. Gramm, NRR M. Cheok, NRR G. Holahan, NRR M. Cunningham, RES* T. King, RES (7 D. Fischer, NRR G. Parry, NRR f N. Gilles, NRR R. Woods, NRR R. Gramm, NRR M. Rubin, RES Industry Reoresentatives

/ jd B. Bradley, NEI*

G. Krueger, BWROG*

T. Pietrangelo, NEI NRR Office of Nuclear Reactor Regulation RES Office of Nuclear Regulatory Research -

NEI Nuclear Energy Institute BWROG Boiling Water Reactor Owners Group 9003250293 971121 PDR 3077 ACRS 6 // - f Of C/ $

PDR 1 (tri; S

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10/21-22/97 Subcommittee Meeting A complete list of meeting attendees is in the ACRS Office File, and will be made available upon request. The presentation slides and handouts used during the meeting are attached to the office copy of these minutes.

October 21, 1997 Introduction Dr. George Apostolakis, Chairman of the Subcommittee on Reliability and Probabilistic Risk Assessment (RPRA) convened the meeting at 8:30 a.m. and introduced the Members of the Subcommittee. He stated that the purpose of this meeting was to continue the Subcommittee's review of the matter included in the Staff Requirements Memorandum dated May 27, 1997, regarding the use of uncertainty versus point values in the PRA-related decisionmaking process. The Subcommittee also reviewed the public comments and the expected changes to the proposed Standard Review Plan (SRP) sections and associated Regulatory Cuides for risk-informed, performance-based regulation.

Dr. Apostolakis stated that the Subcommittee had received no written comments or requests for time to make oral statements from members of the public.

NRC Staff Presentation Messrs. Thomas King, RES, and Gary Holahan, NRR, led the discussions for the NRC staff. Mr. Mark Caruso, NRR presented a summary of the major public comments on the draft Regulatory Guides and Standard Review Plan (SRP) sections for risk-informed, performance-based regulation. Messrs. Mike Cheok, Dave Fischer, Nanette Gilles, Robert Gramm, and Gareth Parry, NRR, provided supporting discussion. Significant points made during the discussion included:

• The purpose of this briefing session was to inform the Subcommittee of the status of plans to finalize the Regulatory Guides and SRP sections, exchange views and discuss options to resolve issues, and to confirm a schedule for future meetings regarding these matters.

e The focus of this briefing was the major public comments on draft Regulatory Guide DG-1061 and SRP Chapter 19 (General Guidance) with limited discussion of the individual applications for inservice testing (IST), Technical Specifications (TS), and gradeo quality assurance (GQA).

Reliability & PRA 10/21-22/97 Subcommittee Meeting o The staff expects to resolve issues related to PRA quality through an industrial standards development initiative being coordinated by the American Society of Mechanical Engineers (ASME). Therefore, the staff is deferring work on NUREG/CR-1602, "The Use of PRA in Risk-Informed Applications."

e Extensive public comments were received on the draft documents and a public workshop was held in August 1997 to discuss these comments.

o Comments on DG-1061 and SRP Chapter 19 were related to the following principal subjects: PRA standards, acceptance guidelines, integrated decisionmaking, licensing issues, licensee burden, staff review process, and implementation issues. Specific issues highlighted in the public comments included:

- Concern that NUREG/CR-1602 contains guidance requiring state-of-the-art PRAs in support of all risk-informed applications.

- Concern over acceptance guidelines including: use of core damage frequency (CDF) as a benchmark for decisionmaking, treatment of very small increases in risk, treatment of uncertainties, guidelines for temporary changes and shutdown operations, and guidelines for use of PRA Level 3 analysis. These acceptance guidelines represent the major policy issues requiring resolution. The staff is preparing a separate policy paper to address these issues in detail.

- Concern that quantitative criteria using CDF, large early release f requency (LERF) , and conditional core damage probability (CCDP) will be used as " speed limits" for decisionmaking rather than guidelines.

Concern over the need for better definition of the roles of defense-in-depth and safety margins in integrated decisionmaking. Also, concern for better definition of what constitutes increased management attention and how the staff will consider " bundling" of multiple changes.

- Concern that the definition of current licensing basis (CLB) is too broad.

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10/21-22/97 Subcommittee Meeting Concern that requirements for monitoring and corrective action are too great for what may be very small increases in risk. Similarly, documentation requirements may be excessive.

Concern over consistency in staff review and interpretation.

Concern that tracking of cumulative changes in risk constitutes a defacto "living PRA."

e Major comments on IST guidance (DG-1062 and SRP Chapter 3.9.7) included:

- Comments proposed the NRC endorse the ASME Code cases in lieu of developing parallel guidance.

Comments suggested the use of Maintenance Rule monitoring and corrective actions at the plant or system-level in lieu of component-level monitoring of high and low safety significant components. The comments asserted that monitoring, trending, and corrective action for low safety significant components (LSSCs) is an unnecessary burden.

Comments suggested greater use of expert panels, as opposed to sensitivity studies, to resolve PRA model shortcomings.

• Major comments on TS guidance (DG-1065 and SRP Chapter 16.1) included:

i Remove the guideline for incremental CCDP for allowed outage time (AOT) changes and rely on the general guideline for small changes in CDF.

Perform configuration risk on a broader basis such as the Maintenance Rule rather than requiring a Configuration Risk Management Program (Tier 3) in TS.

Update DG-1065 to reflect acceptable alternatives used in the pilots (i.e., cross comparisons to verify and validate PRA results).

Clarify guidance to allow for other risk-informed applications beyond A0Ts and extended surveillance test intervals.

i

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Reliability & PRA 10/21-22/97 Subcommittee Meeting e Major comments on GQA (DG-1064) included:

Need more specific guidance on the PRA required for GQA purposes.

Simplify the SSC (structures, systems, and component) categorization process. There is no need for additional monitoring or root cause analysis of LSS components.

Credit should be given for Maintenance Rule program aspects. Consensus Standard NOA-1, 1996 should be used for GQA.

- Revise DG-1064 to reflect pilot program experience.

Presentation by Industry Representatives Messrs. Biff Bradley of the Nuclear Energy Institute (NEI) and Greg Krueger of the Boiling Water Reactor Owners' Group (.BWROG) provided presentations to the Subcommittee. Mr. Bradley discussed industry issues relative to risk-informed regulation.

Mr. Krueger discussed the BWROG Probabilistic Safety Assessment (PSA) Certification Process.

Significant points made during Mr. Bradley's presentation included:

e Risk-informed initiatives should provide the basis for some regulatory relief without requiring " gold-plated" PRAs. The industry believes the transition to risk-informed regulation should be an evolutionary process of incremental change starting with the use of existing PRAs.

e There is a need for the NRC to complete its review and approve some of the current pilot applications to provide a basis for continued or increased interest on the part of the industry.

e There is industry concern that risk-informed regulation is actually " regulation plus" in that all regulatory requirements still exist and the NRC will now have expectations for additional risk-informed analysis.

e Major industry concerns include: overall cost / benefit, emphasis on absolute CDF and LERF as acceptance limits, gold-plated PRAs, treatment of uncertainty, and uncertainty in consistency and timeliness of the regulatory review process.

' Reliability & PRA 10/21-22/97 Subcommittee Meeting' Significent points made during Mr. Kruegers's presentation included:

-e The.BWROG is taking an active role in assuring PSA quality through a graded certification process. The process identifies levels of excellence by verifying the accuracy, realism, completeness, and documentation of plant-specific-PSAs.

• The peer review process focuses on.the maintenance and updating of PSAs as well as details of these PSAs.

e The expectations for PSA model elements and attributes change'as the associated grades change. The PSA grade levels are:

Grade 1: Useful for identifying severe accident vulnerabilities with Individual Plant Examinations (IPEs).

Grade 2: Useful for risk ranking supplemented-by deterministic input such as the Maintenance Rule Grade 3: Useful for risk significance with deterministic input such as IST, ISI and QA Grade 4: Useful as a primary basis for decisionmaking such as Technical Specifications e The-process establishes a uniform, reproducible method of assessing PSA quality and provides a usable critique in identifying areas for improvement e The process provides for cross pollination of utility experience.

October'22, 1997 Introduction Dr. George Apostolakis, Chairman of the Subcommittee on RPRA convened the meeting at-8:30 a.m. He stated that the purpose of this meeting was to continue the Subcommittee's review of the matter included in the Staff Requirements Memorandum dated May

~

27, 1997,- regarding the' use of uncereainty versus point values in the PRA-related decisionmaking procesa. .The Subcommittee also

. reviewed the public comments and the expected changes to the proposed Standard Review Plan - (SRP) sections and associated a

o

".4 Reliability &'PRA 10/21-22/97 Subcommittee Meeting _

Regulatory Guides for risk-informed, performance-based m regulation.

Dr. Apostolakis' stated that the Subcommittee had received no written comments or. requests for time to make oral statements from members of the public~ .

HEC Staff Presentation Messrs. Thomas King, RES, and Gary Holahan, NRR, led the discussions for the NRC staff. Mr. Mark Cunningham, RES, and

- Gareth Parry, NRR, provided supporting discussion. The staff discussed the proposed major changes to DG-1061 and SRP Chapter

19. Significant points made during the discussion included:

e The staff discussed specific changes proposed for DG-1061 and stated that similar changes would.be made to SRP Chapter

19. The staff did not discuss SRP Chapter 19 as an individual document.

e- Many of the proposed changes relate to resolution of the policy. issues.

e Specific changes were proposed for the following:

- Paragraph 1.3, Scope: Modify paragraph on regulatory framework to be consistent with PRA Policy on burden reduction and not to imply uncertainties only exist in PRAs. Add paragraph on scope of applications for risk increases / decreases.

Paragraph 1.4, relationship to other documents: Drop reference to NUREG/CR-1602 and add reference for DG-1063 related to ISI.

- Paragraph 2.1, Philosophy: Add'a statement indicating that_the staff expects licensees to propose changes involving risk reductions. This statement was suggested, in part, to provide balanced staff

. expectations regarding allowance for possible increases in risk.

Paragraph 2.4, Engineering analysis:

Define region of "very small" calculated risk increases; allow all plants, regardless of baseline CDF/LEP.F , to make changes with very small increases in

- risk; add guidance not to require uncertainty analysis for risk reductions and small increases in risk.

L.

Reliability & PRA 10/21-22/97 Subcommittee Meeting Consider expanding the discussion on the use of PRA for different types of applications (i.e., risk categorization, detailed changes, etc.).

Add guidance to address " bundling" or packaging of related changes.

Clarify treatment of uncertainties including: use of qualitative risk factors; guidance for very small changes and risk reduction - not to require uncertainty analysis for baseline CDF/LERF. Also, clarify what is meant by management attention regions including:

guidance for situations requiring uncertainty analysis for baseline CDF/LERF, use of mean values, identify sources of uncertainty, accounting for unanalyzed modes of operation with bounding analysis or qualitative arguments, and guidance for Level 3 PRA to show margin to the quantitative health objectives (QHOs).

Clarify guidance for " management attention" and tracking of cumulative impact of changes.

Paragraph 2.5, Implementation and monitoring: Clarify guidance to focus on most risk-significant SSCs and how changes can be made based on performance monitoring.

Paragraph 2.7, Quality assurance: Expand discussion of current QA guidance and factors affecting PRA quality.

Also, discuss the role of industry certification programs.

Paragraph 3.3, Licensee submittal: Clarify to reduce potential documentation burden.

- Appendix B: Expand to include external events and shutdown operations.

Subcommittee Questiens and Comments The Subcommittee and staff extensively discussed the role of NUREG/CR-1602. The staff stated that it was intended to serve as an informational guide, however, the industry perceived it as prescribing a " gold standard" for PRA quality. The staff has stopped all work on the subject document pending the development of guidance by ASME and the Owners' Groups.

Dr. Miller questioned whether the proposed guidance placed too much emphasis on numbers. The staff stated that this matter needs clarification. Dr. Apostolakis suggested the staff clarify the guidance to emphasize the importance of qualitative aspects

L Reliability ~&LPRA -9'- 10/21-22/97 Subcommittee Meeting..

of integrated ~decisionmaking. The staff agreed to make the suggested changes.

The Subcommittee and staff extensively discussed the meaning of-the region for "increas6d management attention." -Dr. Apostolakis stated.that the boundary for this region was somewhat-fuzzy for integrated.decisionmaking. He stated that there.may be some benefit in use of the figures. discussed during previous meetings-in, terms of clarifying this matter. He suggested that the staff reconsider use of such a figure. Dr. Apostolakis and the Subcommittee Members suggested that this figure contain a region Lwhere there is negligible calculated change. He also suggested the language in Paragraph 2.4 of DG-1061.also be modified. The staff agreed to consider these changes and discuss a possible revised figure at the November ACRS meeting.

'DrApostolakis suggested that the staff add a list of the major

-contributors to uncertainty. The staff agreed to consider this request. The staff requested to discuss the matter of elevating CDF to a fundamental safety goal during the November 12-13, 1997 Subcommittee meeting. Dr. Apostolakis agreed to include this in the agenda for that meeting.

The Subcommittee and staff discussed the issue of bundling multiple changes in a single request. The staff stated that the guidance emphasizes that these changes must be related. Dr.

Apostolakis questioned whether changes could be partitioned such that the collective risk would be acceptable on a parts-only basis. The staff stated that they would consider the sum of the individual parts as they were related to the request under consideration as well as related previous requests. Dr.

Apostolakis suggested this be clarified in the guidance. The staff agreed to this request.

At the conclusion of the meeting, Dr. Apostolakis noted that the KACRSfneeded to respond to the Commission's SRM on uncertainty.

He suggested that the ACRS address this matter in its letter commenting on'DG-1061 and SRP Chapter 19.

Followun Actions The Subcommittee requested the following document be provided

~following_the meeting:

e Dr. Apostolakis' requested the BWROG to provide the Subcommittee with copies of its PSA certification guideline.

Mr. Krueger agreed to this request and provided these documents:on November 11, 1997.

Reliability & PRA 10/21-22/97 Subcommittee Meeting Dr. Apostolakis requested the staff to brief the Subcommittee on-its proposed policy paper on performance-based regulation during its next meeting on November 12-13, 1997. The staff agreed to request cognizant personnel to conduct this briefing.

'The Subcommittee requested the NEI representative to discuss the PRA certification processes being pursued by the other Owners' Groups during the November 12-13, 1997 Subcommittee meeting. Mr.

Bradley agreed to this request.

Backaround Material Provided to Subca==4ttee for this Meetina

1. Subcommittee status report

2. Memorandum dated October 8, 1997, from Commissioner Diaz, to John Larkins, ACRS,

Subject:

Safety Goal

3. Public comments from Entergy and Detroit Edison

4. Handout for Commission briefing on SECY-97-234

5. SECY-97-234, " Quarterly Status for the'Probabilistic Risk Assessment Implementation Plan," dated October 14, 1997

6. SECY-97-229, " Graded Quality Assurance /Probabilistic Risk Assessment Implementation Plan for the South Texas Project Electric Generation Station," dated October 6, 1997

7. SECY-97-221, " Acceptance Guidelines and Consensus Standards for Use in Risk-Informed Regulation," September 30, 1997

8. Standard Review Plan Sections and Regulatory Guides for Risk-Informed, Performance-Based Regulation - issued for public comment in June 1997 9.- Memorandum dated October 16, 1997, from John C. Hoyle, SECY, to L. Joseph Callan, EDO, NRC,

Subject:

Staff Requirements -

SECY-97-208 - Elevation of the Core Damage Frequency Objective to a Fundamental Commission Safety Goal

10. SECY-97-208, " Elevation c>f the Core Damage Frequency Objective to a Fundamental Commission Safety Goal," dated September 17, 1997 Presentation Slides The presentation slides and handouts used during this meeting are attached to the office copy of these minutes.

o *******************************************************

Note: Additional details of this meeting can be obtained from a transcript of this meeting available in the NRC Public Document Room, 2120 L Street, N.W. Washington, D.C. 20006, (202)'634-3274, or can be purchased from Ann Riley & Associates, LTD., 1250 I Street, N.W.,

Suite-300,. Washington, DC 20005, (202) 842-vo34.