ML20148K364

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Summary of 871216 Meeting of ACRS Subcommittee on Reliability Assurance in Washington,Dc Re Equipment Qualification Risk Scoping Study
ML20148K364
Person / Time
Issue date: 01/05/1988
From:
Advisory Committee on Reactor Safeguards
To:
Advisory Committee on Reactor Safeguards
References
ACRS-2542, NUDOCS 8801270602
Download: ML20148K364 (8)


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SUMMARY

/ MINUTES OF THE DECEMBER 16, 1987 MEETING OF THE ACRS SUBCOMMITTEE ON RELIABILITY ASSURANCE (EO-RISK SCOPING STUDY)

WASHINGTON, D.C.

A meeting was held by the ACRS Subconinittee on Reliability Assurance on December 16, 1987. The purpose of the meeting was to explore the current status of the Equipment Qualification (EQ) Risk Scoping Study being performed by the NRC Office of Nuclear Regulatory Research.

Notice of this meeting was published in the Federal Register on Monday, Noverber 30, 1907. The Subcorriittee received no oral or written state-ments from the public. The meeting was entirely open to the public.

The meeting began at 8:00 a.m. and ended at 11:15 a.m. Richard Major was the cognizant ACRS Staff Ergineer for the meeting.

Attendees:

ACRS NRC D ylie, Chairman C Sullivan, RES J. Ebersole, Member D. Gupton, RES C. Michelson, Member M. Vagins, RES R. Major, Staff G. Peidenhamer, RES R. Savio, Staff H. Walker, RES G. Brown, Fellow M. Dey, RES R. Wilson, RES Sandia L. Bustard Science Applications Int'l Corp.

D. Dahlgren G. Medford M. Bohn A. Kolacykouski Others G. Langford, Pechtel P. Beliveau, NUMARC pg p/4",i g.. s. @Q .

]<e G. Fotoponlos, Bechtel

[l ' e. S t C. Lowe, NMS M

[ I. Caffenlorry, Heritage Report.

8801270602 880105

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. Minutes / Reliability Assurance 2 Subcommittee Meeting, Dec.16, 1987 This meeting was an initial briefing by the NRC Staff on an Equipment Qualification Risk Scoping Study. The Subcommittee was briefed prior to any results being produced by this effort; this session was for information only. A copy of the schedule is enclosed.

Chairman's Introduction - C. Wylie Mr. Wylie comented that the NRC had had a research effort to study equipment qualification. This effort covered a ten year period (1975-1985). When this program ended prior to its completion, the ACRS reconnended in June 1986 that the EQ research to assess survivability of electrical equipment when subjected to hostile conditions including severe accidents be funded. The ACRS stated, "...Research is vital to preventing accidents as well as mitigating the consequences of accidents, should they occur." In this light, the Subcommittee was anxious tn see the plan for the EQ Risk Scoping Study.

Introduction by Staff - Moni Dey, RES Dr. Dey explained that the objective of the EQ Scoping Study was to determine the risk importance and priority for NRC funded EQ research.

Electrical equiprent (and mechanical equipment that is electrically driven) that are essential to preventing accidents, as well as mitigating the consequences of accidents, will be studied to determine their risk significance and prioritize the need for further study, EQ'

flirutes/ Reliability Assurance 3 Subcommittee M:eting, Dec.16, 1987 issues pertaining to the performance of the above equipment will be studied.

Results of this research will be used to determine the need for further EQ research (develop / revise regulations or regulatory guides), priori-tize the research, and study the need for identifying new generic issues.

Results from the E0 Scoping Study are expected by March 1988. The Staff wishes to meet with the Subccruittee in March 1988 to discuss results and would like ACRS coments on this effort at the April 1988 ACRS meetir.g.

E0-Risk Scoping Task Structure - Larry Bustard, Sandia The EQ-Risk Scoping Study will attempt to assess the impact of elec-trical equipment environmental qualification or lack thereof on reactor risk and its uncertainties. It is also trying to identify any analyses or testing that may be necessary to reduce the risk or its uncertainties steming from lack of oualification of equipment important to safety.

Among the EQ lssues to be addressed are:

1. Does the current EQ process adeouately demonstrate equipment qualification for the design basis?

Minutes / Reliability Assurance 4 SubcomMtee Peeting, Decc16,1987

2. Does the current EQ process demonstrate equipment operability in agreement with current PRA assumptions?

The project approach being taken in the EQ Scoping Study is to first identify "candidate" equipment operations that must be accomplished in harsh environments. Second, prioritize "candidate" equipment op-erations. Third, for selected eoutpment operations, identify in more detail their risk impact, important sequences, typical harsh environ-ments, subcomponent locations, fragilities, etc. Fourth, for selected equipment operations, identify impact of EQ issues on equipment function. Identify data sources and data base shortcomings. Finally, the risk significance of various EQ issues will be assessed and conclusions reported.

Pisk Significant Equipment / Operations for Identified BWR and PWR Plants

- Alan Kolaczkowski, SAIC The purpose of this task is to identify from a PRA perspective important equipment operations which could be impacted by a harsh environment.

The process to accomplish this involves a literature review to identify risk significant equipment. Also employed is a formalized process of ranking of equipment based in eouipment importance, eouipment location, and potential environments for each accident type reviewed. The ulti-mate goal is to identify areas where PRA results might be affected by equipment qualification knowledge. ,

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Minutes / Reliability Assurance 5 Subcommittee Meeting, Dec.16, 1987 v A summary of the literature review process identified PORV's, SRVs, MSIVs, pressure sensors, and containment heat removal systems as poten-tial EQ significant equipment. The literature review also pointed out the need to develop a process that focuses on identifying , risk signifi-cant equipment with EQ potential as past work has not been designed to accomplish this.

The fomalized process for ranking equipment qualitatively considers equipment locations in terms of potential for seeing a harsh environ-ment. The process also uses risk increase and risk reduction calcu-lations to identify important equipment. 17 BRW and PWR issues resulted frem this process (e.g. containment isolation velves, low pressure inj.

pump rotors, containment fans, pressurizer level instrumentation). All literature review issues were identified egain in the fonnalized pro-Cess.

It is believed that the list of 17 equipment operation issues, with significant potential for harsh environment exposure, represents a broad spectrum of both core danage and total plant risk operational concerns.

The issues will serve as input to other program tasks.

Risk Sionificance of EQ Issues - Larry Bustard, Sandia The risk significance of EQ issues was illustrated using the example of containment fan coolers. It was noted that PRAs characterize equipment performance during accident conditions by usually astuming normal

. Minutes /P.eliability Assurance 6 Subcommittee Me ting, Dec.16, 1987 cperation failure probabilities. However, sometimes accident perfor-mance assumes a step-function change in failure probabilities.

EQ insights were also found to be useful towards defining accident failure probabilities:

Where might PRA analyses assume step-function changes in failure probabilities.

What are upper or lower bounds on accident environment failure prcbabilities.

khen during accident exposures do failure probabilities significantly diverge from normal operation valves.

The risk changes associated with modified failure probabilities are useful for characterizing the risk significance of EQ issues.

Subcomittee Comments:

The Subcomittee noted that there should be an interrelation between l

this EQ effort and the A-17 Systems Interaction program. Failures caused by harsh environments (floods, fires, loss of air cooling) should be factored into the systems interaction process.

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-Minutes / Reliability Assurance 7 Subcommittee Meeting, Dec.16,:1987 d It was felt special attention should be paid to harsh environments that occur in the balance of plant. The subsequent loss of support equipment could be significant.

A concern was raised over the treatment of fires. The treatment of fires has been segregated into a separate fire risk scoping study.

Caution should be exercised to ensure this topic receives adequate attention.

A significant problem could be the abnormal operation of a piece of equipment. This would be some intermediate area between failure (complete loss of function) and normal operation. Thought should be given to problems created when equipment bebe.ves in unexpected ways.

Certain EQ concerns can be raised when seismic events are considered.

Future Action:

A Subcommittee chairman's report will be siven to introduce this effort to the ACRS during the January 1988 meeting. Results from the EQ-Risk Scoping Study will be ready for Subcommittee consideration in March 1988. Full Conmittee comments are requested on this study during the April 1988 ACRS meeting.

j NOTE: Additional meeting details can be obtained from a transcript

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  • Minutes / Reliability Assurance 8 Subconsnittee Meeting, Dec.16,1987 a

of this meeting available in the NRC Public Document Room, 1717 H St., NW., Washington, D.C. or can be purchased from Heritage Reporting Corporation,1220 L Street, NW.,

Washington, D.C. 20005(202)628-4888.

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