ML20210H273
| ML20210H273 | |
| Person / Time | |
|---|---|
| Issue date: | 05/16/1997 |
| From: | Apostolakis G Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-3050A, NUDOCS 9708130331 | |
| Download: ML20210H273 (10) | |
Text
CERTIFIED BY; G2ptga Apoctolakia - 5/16/97 0 ,,,gg
- ADVISORY COMMITTEE ON REACTOR SAFEGUARDF fD2 f/N/47 MEETING OF THE SUBCOMMITTEE ON PROBABILISTIC RISK ASSF"6 MENT MEETING MINUTES - FEBRUARY 20-21, 1997 ROCKVILLE, MARILAND INTRODUCIlQH The ACRS Subcommittee on Probabilistic Rink Assessment (PRA) met on February 20-21, 1997, at 11545 Rockville Pike, Rockville, MD, in Room T-2B3. The purpose of this meeting was to continue the ACRS Subcommittee review of the staff's approach to codify risk-informed, performance-based regulation through the development of Standard Review Plan (SRP) sections and cssociated Regulatory Guides (RGs). 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 5:34 p.m. on February 20 and adjourned at 5:56 p.m.
on February 21.
ATTENDEES ACRS G. Apostolakis, Chairman R. Seale, Member J. Barton, Member W. Shack, Member I. Catton, Member M. Markley, ACRS Staff M. Fontana, Member R. Sherry, ACRS Fellow T. Kress, Member E. Abbott, Consultant D. Miller, Member J. Carroll, Consultant D. Powers, Member NRC Staff D. Fischer, NRR G. Holahan, NRR N. Gilles, NRR T. King, RES R. Gramm, NRR R. Woods, RES B. Hardin, RES T. Pratt, SNL*
Sandia National Laboratory (SNL).
I Industry Reoresentatives < f 5oI R. Grantom, STP L. Martin, STP A. Heymer, NEI 3. Bradley, NEI 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.
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, Introduct%2D Dr. George Apostolakis, Chairman of the Subcommittee convened the meeting and reviewed the purpose of the meeting and introduced the ACRS Members, consultants, and staff in attendance. He noted that all ACRS Members were in attendance at this subcommittee meeting. He stated that the purpose of the meeting was to continue the Subcommittee's discussion of the staff's approach to codify risk-informed, performance-based regulation through the development of Standard Review Plan (SRP) sections and associated regulatory guides. He noted that the Subcommittee had previously met to discuss these mattern on October 31, November 1, 21, and 22, 1996, and January 28, 1997.
Dr. Apostolakis stated that the Subcommittee had received no written comments or requests for time to make oral statements from members of the public. He noted that Messrs. Rick Grantom and Lawrence Martin of Houston Lighting and Power Company (South Texas Project) would make a presentation on pilot plant perspectives regarding graded quality assurance (GOA). He informed the Subcommittee that there was one change in the agenda. Messrs. Biff Bradley of the Nuclear Energy Institute (NEI) and Doug True of ERIN Engineering would not make a formal presentation regarding large, early release frequency (LERF) as was indicated in the public agenda. However, Mr. Bradley was in attendance and was offered an opportunity to provide comments.
NRC Staff Presentation General Guidance Messrs. Gary Holahan, Director, Division of Systems Safety and Analysis, NRR, and Thomas King, Deputy Director, Division of Systems Technology (DST), RES, led the discussions for the NRC staff. Messrs. Mark Cunningham, Chief, Probabilistic Risk Analysis Branch, PRAB/RES, and Robert Jones, Chief, Probabilistic Safety Assessment Branch (SPSB), DSSA/NRR, provided supporting discussion. Mr. Trevor Pratt, SNL, provided a discussion of the Appendices for these documents.
Messrs. Holahan and King provided an overview of the general approach and process; reviewed the general guidance documents (RG/SRP and Appendices); and discussed the overall content of the individual applications for Technical Specifications (TS),
Inservice Testing (IST), and graded quality assurance (GQA).
Significant points made during the discussion include:
e The staff requested the Committee provide a letter at the March 6-8, 1997 ACRS meeting, regarding the general guidance documents and applications for TS, IST, and GQA. The staff stated that they also plan to issue NUREG-1602 for public comment but were not requesting ACRS comment at this time.
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l e Use of the ERP/RG approach is voluntary for licensees wanting to make risk-informed, performance-based changes to the current licensing basis (CLB).
e The pilot plants for risk-informed initiatives are:
TS: all 10 Combustion Engineering design plants IST: Comanche Peak and Palo Verde GQA: Palo Verde, Grand Gulf, and South Texas Project e The overall approach is based on and assumes that the following fundamental safety principles are met:
Meet regulations (or propose change / exemption)
Maintain defense-in-depth philosophy Maintain sufficient safety margins philosophy Increases in risk and their cumulative effect are small and do not cause the NRC Safety Goals to be exceeded Implement the approach utilizing performance-based monitoring and feedback strategies e Expectations for implementation include:
Assessing all safety impacts The scope of analysis supporting the change should cover all structures, systems, and components (SSCs),
operating modes, initiators affected by the proposed change and reflect the as-built plant, as operated Subsidiary objectives of the NRC Safety Goal Policy are used to define benchmark risk levels for decisionmaking Core damage frequency: 10E-4/ reactor-year Large. early release frequency: 10E-5/ reactor-year Proposed changes should be in small increments (<10% of benchmark CDF/LERF values)
Uncertainty / sensitivity analysis is appropriate for proposed changes e Performance must be taonitored to verify key assumptions and to check areas of large uncertainty Dr. Apostolakis questioned whether a licensee could provide risk-informed submittals without a good PRA. The staff stated that licensees could use existing PRAs but emphasized that certain parts may have to be enhanced to provide suitable information for the staff to make a decision. They stated that the quality issue could be viewed as an application-specific issue and that a
" state of the art PRA" would not be expected. They added that the quality of PRAs should improve as application-specific submittals are pursued. The staff stated that additional analysis would be expected for areas where risk could not be quantified and that these analyses should consider other modes of operation (i.e., shutdown, low-power, external events, fire, 3
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n etc.). Dr. Apostolakis stated that PRAs should be commensurate with the requested-application or submittal'.
-Technical specifications Mr.-Roy Woods,-PRAB/RES, and Ms. Nanette Gilles, Technical Specification Branch'(TSB), NRR, led the discussions on risk ~
informed.TS. Mr. Millard-Wohl provided supporting discussion.
Significant points made during the discussion include:
- The four-element approach to integrated decisionmaking includes: 1) definition of the proposed change, 2) Conduct of appropriate engineering evaluations, 3) development of implementing and monitoring strategies, and 4) submittal of the proposed change.
e For changes in allowed outage times (AOTs) and surveillance i test intervals (STIs), the staff would expect the licensee to demonstrate improvement in operational safety, consistency of risk basis in requirements, or reduction in unnecessary burden.
o Proposed changes are expected to meet the current regulations.
e The staff would expect a three-tiered approach to risk-informed Technical Specification AOT evaluationc:
- Tier 1
upper bound guidelines on quantitative risk i measures Tier 2 avoidance of risk significant plant configurations Tier 3: risk-informed configuration control d
3 e The proposed SRP/RG would allow for licensees to propose implementation and monitoring strategies using the three-tiered approach and monitoring through the Maintenance Rule.
j Drs. Powers and Apostolakis questioned the consideration of
" instantaneous" or " point-wise" spikes in risk. They also questioned the period of time over which risk.is integrated. The staff stated that individual limits could be established.but
. noted that-a significant initiator has to exist to have such a
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high level of short-term risk. The staff stated that such a i limit is not needed.
Dr. Kress questioned the use of sequences in analyzing incremental versus overall plant risk. The staff stated that this was difficult because of the potential number of sequences
, at any particular plant. The staff also stated that the approach to development of the TS application was dominated by the Maintenance Rule (monitoring, configuration control, AOTs and r 4 t
, STIs, etc.). Mr. Carroll questioned the need for_the SRP/RGs to be prescriptiveLif:these things-are covered in the Maintenance-
. Rule. The staff stated that it is not clear that the Maintenance Rule covers the full range of situations that may be considered for risk applications.
Inservice _ Testing Messrs. David Fischer, Mechanical Engineering Branch (EMEB), NRR, and Brad Hardin, PRAB/RES, led the discussions for the staff.
Mr. Mike Cheok, SPSB/NRR, and Joseph Colaccino, EMEB/NRR, provided supporting discussion. Significant points made during the discussion include:
- The " classical" IST approach 1) includes American Society of Mechanical Engineers (ASME) Code referenced in 10 CFR 50.55a, " Codes and Standards," for ASME safety-related code class pumps and valves, 2) requires prescriptive testing of a "like" components, 3) requires relief requests be submitted l to the NRC for changes in test interval or acceptance criteria, and 4) allows for NRC endorsement of ASME code cases, o The risk informed approach 1) starts with ensuring the p3 ant is designed and operated according with the current licensing basis, 2) ensures that the PRA reflects the_ actual
, plant, 3) categorizes components as either high or low safety significant (HSSC or LSSC), and 4) requires changes to the CLB be justified in accordance with the five principles.
- Regulatory approval could ha an alternative to the Code requirements as allowed by 10 CFR 50.55a (a) (3) (i) .
Dr. Seale questioned _the status of the ASME code cases. The staff stated that the SRM dated the January 22, 1997, allows the-staff-to go forward without completion of the code cases with the approval of the Director of NRR. They further stated that-the risk-informed applications for IST and inservice inspection (ISI) will need to be codified through rulemaking per 10 CFR 50.55 (a) when available.
Dr. Powers and Kress questioned the consideration of " total" risk (1.e...fu11 power operation,-shutdown, low power, and transitions) in the IST application. The staff stated _that their values were largely based on power operations, and acknowledged that the application had not_ fully considered the full range of operational states. Dr. Powers asked how incremental changes could be approved if they_did not consider total risk.- The staff stated that the monitoring program.would provide useful decision-making information.
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4 L, Graded Quality Assurance 4
Messrs.-Robert Gramm, Quality Assurance and Maintenance Branch 4
(HQMB), NRR, and-Roy Woods, PRAB/RES, led the discussion for the NRC staff. Mr.-Stephen Dinsmore provided supporting discussion.
] Significant points made during the discussion include:
e The initial process to allow for graded approaches to 4
quality assurance was provided in SECY-95-059 where the
- process directs the determination of SSC safety significance, application of-QA controls based on safety i function, program controls for root cause determination and corrective actions, and operating experience feedback, o The four-olement approach to integrated decisionmaking is j applied, o The pilot applications for GOA risk-informed initiatives are mostly in the area of procurement controls.
Dr. Powers stated that QA is neither quantitatively nor explicitly modeled in PRA. He noted that this is an area where risk insights could be used much more than has been proposed in the guidance documents. The staff stated that modeling GQA may
- i. be impossible and that the focus should be on monitoring and
- feedback.
Dr. Shack expressed the view that the risk-informed regulatory g
approach.is layered over top of what already exists. The staff stated that it may be reasonable to expect more, for what is given up, to provide assurance that sufficient safety is
. maintained. Dr. Powers stated that emphssis should be placed on t what is important rather than what is being given up. He stated i: that the less important things could be monitored.
Industry Prscantation South Texas Project Mensrs. Rick Grantom and Lawrence Martin, Houston Lighting and Power company, provided a-presentation on their perspectives as a 3- pilot plant for GQA at the South Texas Project (STP) nuclear plant. Significant-points made during the discussion include:
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- o STP considers the initiative in GQA to be part of a Comprehensive Risk Management Plan. The licensee has five other applications submitted, waiting to be submitted, or in progress GQA, IST, TS, Appendix J, and MOVs).
e -The licensee stated that these applications can improve both
.- safety and cost. Major cost savings can be realized in GQA
- for procurement.
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, e Industry concerns are related to the limited progress in gaining NRC approval for these applications. Early experience emphasized the deterministic approach. They stated that industry has an expectation of a more probabilistic approach, but the documents are not yet available to the public.
- Regulations and requirements which are marginal to safety, or adverse to safety must be adhered to. Nevertheless, the industry prefers a slow, incremental change rather than rule changes or exemptions which are monumental efforts for licensees.
- Based on the discussions by the NRC staff, the licensee expressed concern that these initiatives would be an additional layer of regulatory burden rather than improvements. STP representatives also stated that some utilities were cutting back on their PRA staffs because they did not perceive a payback for the investment. STP requested a recommendation for the staff to release the SRP and regulatory guides for public comment.
Several Subcommittee Members questioned why only items outside 10 CFR Part 50, Appendix B, were being considered for application in GOA. The staff stated that the regulations for safety-related structures, systems, and components (SSCs) had not changed and the requirements still apply. The staff added that it is difficult to see the aggregate effects or reduced safety created by removing items from the QA Program. Industry representatives expressed concern that some licensees are avoiding the use of PRA for fear that it will cause areas to be added to Appendix B requirements. They noted that some licensees are reducing staffing in this area for this reason and because of the lack of apparent progress on the pilot applications.
Nuclear Energy Institute Mr. Biff Bradley and Adrian Heymer of the Nuclear Energy Institute provided remarks at the conclusion of the meeting.
Significant points made during the discussion include:
e Many licensees are reducing their PRA organizations due to the lack of apparent progress by the pilots, the perception that risk-informed regulation could be an onerous process, and the extensive requests for additional information (RAIs) for the current pilot plants.
- GQA makes good business sense not because a regulation is satisfied, but because it frees resources to be better spent in other areas which are more important to safety.
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', subca--ittee cc rnts and Concerns (General)
Dr. Apostolakis expressed the-view that the NRC still does not have a codified definition of performance-based regulation and noted the-findings in-the Inspector General's report regarding-this matter. -The staff noted that the SRM dated January 22, 1997, _ requires the staff to develop a separate plan for performance-based regulation.
Dr. Apostolakis expressed the view that the " monitoring program and integrated decision-making" could appear overwhelming. He also stated that integrated decision-making should be elevated to that of a " key principle" because it provides a means by which l partial / incomplete PRAs may be considered. The staff agreed to l evaluate these suggestions.
1 Dr. Apostolakis and Mr. Carroll questioned the-potential perception that the guidance in the SRP/RGs may be perceived as requirements. The staff insisted that any risk-informed submittal is voluntary. Dr. Apostolakis suggested that this view be highlighted in an Executive Summary to general Regulatory Guide (DG-1061). The staff agreed to revise the " foreword" section to emphasizo the vcluntary nature of this approach.
Mr. Carroll questioned staff readiness for implementation. He expressed concern over potential " roadblocks" within the technical divisions that may limit the review and approval of licensee submittals. He cited differences between the general guidance documents and the individual applications reviewed by the subcommittee.- The staff stated that they plans to conduct training workshops to enhance communication with the staff, industry, and public regarding these matters. Dr. Catton suggested the use of case study methods for training and industry representatives offered to support this effort.
At the-conclusion of the Subcommittee meeting, individual Members '
expressed favorable views of the overall approach taken by the staff. Most Members stated that the SRP/RGs should be issued for public comment as soon as practicable. The one notable exception was the RG for GQA. .Drs. Powers, Miller, Catton, and Mr. Carroll stated that RG should not be issued until it is reexamined.
Major objections to the RG for GQA included: 1) that it is too prescriptive, 2) that it is not risk-sensitive in elevating /
reducing items-based on the-full range of risk, and 3) that the document does not reflect the' discussions cf the staff with regard to considering a wide range of submittals that may be submitted / considered.
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- [ F.ollowun Actiqua The Subcommittee requested the staff to provide the following documents:
i e The latest version of SRP sections and associated RGs (pre-decisional, drafts for internal ACRS use only)
. e NU'.EG/CR-5742, Vol. 2, " Feasibility Assessment of a Risk-
, Based Approach to Technical Specifications" 4
e SECY-93-138, " Recommendation on Large Release Definition."
dated May 19, 1993 i
e Combustion Engineering submittals and associated documents for risk-informed-Technical Specification pilot application (9 documents)
Comanche Peak submittal and associated documents for risk-
- informed Inservice Testing pilot application (1 document) e Submittals and associated documents for risk-informed graded
- QA pilot applications:
q e South Texas Project (4 documents)
- Grand Gulf (8' documents) i e Palo Verde (6 documents)
Representatives of the NRC staff agreed to modify SRP and RGs to reflect comments of the Members regarding " defense-in-depth
- philosophy and safety margins.
Backaround Material Provided to Subcommittee for this Meeting
- 1. Letter. dated February 7, 1997, from G. Holahan, NRR, to J.
Larkins, ACRS,'Subj: " Transmittal of Risk-Informed,
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Application-Specific Guidance Documents and Appendices to
'the Risk-Informed General Guidance Documents"
- 2. Appendix A to Draft SRP Chapter 19, "Use of Risk Importance Measures to Categorize Structures, Systems, and Components with Respect to Safety Significance," dated February 7, 1997
- 3. Appendices for Draft SRP Chapter 19, Revision J, "Use of Probabilistic Risk Assessment in Plant-Specific, Risk-Informed Decisionmaking:-General Guidance," dated February 6, 1997
- 4. Draft Regulatory Guide DG-1064, Rev. 4, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Quality Assurance," dated February 6, 1997 i
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- 5. Draft Regulatory Guide DG-1065, Rev. 5, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Technical ,
Specifications," dated February 6, 1997
, 6. - Draft SRP Chapter 16.1, Rev. 11, " Risk-Informed Decisionmaking: Technical Specifications," dated Febrwary 6, 1997
! 7. Draft Regulatory Guide DG-1062, "An Approach for Plant-
! Specific Risk Informed Decisionmaking: Inservice Testing,"
j dated February 7, 1997
- 8. SRP Chapter 3.9.7, Rev. 2A, " Standard Review Plan for the -i Review of Risk-Informed Inservice Testing Applications,"
l dated February 5, 1997 j 9. NRC Staff handout for ACRS meeting, February 6-8, 1997 4
- 10. NEI handout for ACRS meeting, February 6-8, 1997 ,
- . Presentation slides The presentation slides and handouts used during this meeting are '
attached to the office copy of these minutes.
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j NQIE: Additional details of this meeting can'be obtained from ;
a transcript of this meeting available .in the NRC
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i Public Document Room,-2120 L Strbet, N.W. Washington, D4C.-20006, (202) 634-3274, or e.an be purchased from j Neal R. Gross & Co., Inc. Court Reporters and i Transcribers, 1323 Rhode Island Avenue, N.W.
j Washington, D.C. 20005,- (202) 234-4433.
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