ML20215N557

Submits Minutes & Rept of Peer Review Group 860930 Second Meeting in San Francisco Re Technical Competence of Seismic Margin Review Study.List of Attendees Encl

ML20215N557
Person / Time
Site:	Maine Yankee
Issue date:	10/14/1986
From:	Budnitz R FUTURE RESOURCES ASSOCIATES, INC.
To:	Guzy D, Sears P, Whittier D Maine Yankee, Office of Nuclear Reactor Regulation, NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
Shared Package
ML20215N553	List: ML20215N552 ML20215N557
References
NUDOCS 8611060338
Download: ML20215N557 (10)

Text

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FutureReaurces A.uociates, Inc, Enclosure 1 Fl 2000 Center Street Suite 1IH Berkeley. CA O 170-1 115-520-5 t 11 14 October 1986 TO: U.S. Nuclear Regulatory Commission D. Guzy, Office of Nuclear Regulatory Research P. Sears, Office of Nuclear Reactor Regulation Maine Yankee Atomic Power Plant D. Whittier, Manager, Nuclear Engineering and Licensing FROM: Robert J. Budnitz, Chairman of Peer. Review Group for the Maine Yankee Seismic Margin Review Study REF: MINUTES AND REPORT, SECOND PEER REVIEW GROUP MEETING This is the report of the second meeting of the~ " Peer Review Group" that is reviewing the technical competence of the " Seismic Margin Review Study" that is being undertaken on the Maine Yankee reactor plant under sponsorship of the U.S. Nuclear Regulatory Commission.

The meeting was held at the San Francisco Airport Clarion Hotel on Tuesday. Sentember 30, 1986. Attending besides-the chairman were all four of the other Peer Review Group members: Michael Bohn; John Reed; James Thomas; and Loring Wyllie.

Also attending,were representatives of the NRC; the Maine Yankee

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staff and their Yankee Atomic Electric associates; Lawrence

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Livermore National Laboratory staff; LLNL's subcontractors performing the review (EI International and EQE, Inc.); and R.

Kennedy, a consultant to Maine Yankee. The sign-up sheet for the day's session is attached as Attachment A. All attendees attended essentially the entire meeting.

Attachment B shows the agenda for the day's session. The meeting began at 9:00 AM and ended at 6:00 PM. The order of the agenda was followed quite closely, although some of the times were different. All agenda topics and presentations were given, and most of the day was used for technical discussion of aspects of the on-going margins review study.

The minutes of the meeting will be presented as numerically ordered topics, as follows, with commentary included:

8611060338 861104 PDR ADOCK 00000309 P PDR

'.1 ) R. Murray of LLNL led the introductory session, which consisted mainly of a discussion concerning the future schedule for the-review effort. The tentative schedule, as distributed by Murray, is shown as Attachment C. The schedule is judged to~be satisfactory, in the sense that the project is currently 'on ,

schedule' and the participants believe that it can remain on schedule according to the schedule shown in Attachment C. The following specific dates have been decided on for the schedule:

January 15. 1987: first full draft report due from contractors, for limited i distribution only to Peer Review 1 Group, Maine Yankee, LLNL, 2 or 3 NRC staff January 22. 1987: next meeting of Peer Review Group, in San Francisco; attendance by invitation of PRG only February 12, 1987: second draft due, to be distributed to wider distribution including broadly in NRC February 19. 1987: meeting in Washington -with NRC in-house " Working Group on Seismic Margins".

It was also decided that another Peer Review Group meeting would be held sometime after the February time period, to study .the final version of the report to be prepared after the February comments are in.

2) Daniel Guzy of NRC gave a brief summary of the July meeting of the NRC " Working Group on' Seismic Margins". He discussed the Working Group's current thinking, including the selection of a BWR plant as the subject of a possible second trial margins l review study. Newton Anderson of NRC, who is co-chairman of the

{ NRC' Working Group, provided additional comments. This part of the meeting was mainly for information purposes and elicited very

! little discussion.

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3) M. Ravindra of EOE, Inc. gave an overview presentation of the work and preliminary findings of his group, who are the i

. subcontractors doing the fragilities analysis of Maine Yankce.

He discussed a list of key items that will be examined in detail, and another list of items that the fragilities team has already 2

4 analyzed. This presentation ..was lthe subject of much technical discussion on several items of equipment, although a few key items were put off until more detailed discussions scheduled-for the afternoon. Ravindra discussedsvarious data that the utility had furnished ~ to assist the fragilities evaluation, and also discussed his group's use' of various experience data in their analyses. It was emphasized that the Peer Review Group will need access to All data that will be relied on in these evaluations, in order to review its applicability.

.' Among the technical topics covered in Ravindra's presentation were service water piping; heat exchanger supports;. valves ~with-

! extended operators; HVAC fans and blower. supports; cable tray p

motion and a possible interaction with . valve operators; cable trays themselves, including Maine Yankee pull tests; steel frame i

buildings. (specifically the pump house); and several others.

Maine Yankee agreed to provide the summary report to the Peer

Review Group which presents the results of the pull tests conducted on concrete. inserts.

The main thrust of this part. of the session was to familiarize

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the Peer Review Group with the approach being taken by the EQE team.

4) David Moore of EI International next presented an overview of the systems analysis work that his firm is doing. He discussed 4

the first walkdown, and a few tentative ' lessons learned' that

' may assist others in preparing for a first walkdown, such as doing more detailed preparatory study of - HVAC and actuation systems. He emphasized that the first round of systems analysis o

is well under way, with seven fault trees complete and a few more i under development. His group is now going back to answer specific questions that have arisen, in preparation for th'e second walkdown.' The data sources being used were discussed, and it was again emphasized by the Peer Review Group that access to those data sources will be needed. Also, the method of combining seismic and non-seismic failures was covered.

Moore's group will be doing some system cut sets soon, to obtain early guidance for EQE on what items seem to be more important.

However, they do not plan to do' sequence cut sets until after the second walkdown, as is called for in the NUREG/CR-4334 and 4482 guidance.

There was discussion of certain specific items, and the Peer

. Review Group was provided with some detailed fault trees for their study.

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5) Robert Kassawara of EPRI next gave a presentation covering EPRI's on-going seismic margins review project at. Catawba. This review effort is on a schedule not very different from ~ the schedule for NRC's review at Maine Yankee: initial report due early in 1987, final report due a few months later.

While this presentation was mainly intended .for information, it generated significant discussion concerning the . differences between EPRI's and NRC's approaches. EPRI's approach is empha-sizing the CDFM method- for HCLPF determinations, while NRC's approach has not yet settled on one or another method, although it favors the CDFM method if it can be studied enough. EPRI's approach also uses a ' success path' method for the systems analysis rather than a fault-tree / event-tree method. There was much discussion about how to cope with small LOCAs inside containment, which perhaps cannot be walked down and analyzed well. EPRI's analysis at Catawba is studying some relay chatter, hat their analysis is limited to a very few relays on their chosen success path; NRC's approach is not considering relay chatter for the time being, because further research is needed.

The general flavor of this discussion was that both the EPRI review at Catawba and.NRC's review at Maine Yankee will be able to learn much from each other, and continuing cooperation and coordination will be encouraged.

6) Philio Hashimoto of EOE. Inc. gave a long and detailed presentation about three specific technical items that EQE is analyzing: the RWST, the numn house, and one block wall. He presented both CDFM and fragilities analyses of HCLPF values, and his presentation provided a vehicle for extensive discussion about the methodology used, the data relied on, approximations introduced, and whether EQE's analytical approaches were generic or only specific to the item being analyzed.

l It .was pointed out in the discussion that in the analysis approach used for the RWST, the deflection compatibility between anchor bolt and water resistance' . modes is not provided. This needs to be carefully investigated before the capacities from these two modes are combined.

In the course of this discussion, much detail was covered that will not be discussed here. The principal thrust of the Peer Review Group's comments were that there is a need for careful study of both the CDFM and fragilities methods, since the

'results' for HCLPF seem to depend greatly on assumptions made and data chosen. One key aspect was the Peer Review Group's observation that experience data, if available, play a key part of the underlying approach to HCLPF analysis. It was requested that realistic resistance modes be analyzed rather than using 4

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3 design assumptions which are often overly conservative and do not .

' represent the realistic response. '

7) Greaorv Hardy of EOE, Inc. gave a detailed presentation about '

.two other items being analyzed, the diesel day tank and - one -

inverter. located in the switchgear room. This . discuscion i followed the same tenor as the discussion of -Hashimoto's work just earlier.- There was. extensive interaction between the Peer Review Group and the analyst team, and much detailed discussion of data bases and assumptions. Again, _ discussion of experience data-played a key role.

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8) Grea Hardy then gave a briefer presentation, for information purposes only, about'- progress in tracking- down fragilities-information on three key issues: the lead-antimony batteries, ,

the reactor internals and CRDMs, and the fire water threaded gipg. In the battery case, he has been unsuccessful so far in identifying relevant test or experience-data. Therefore, it is the Peer Review _ Group'.s understanding that analysis will .be performed with and without these batteries. For the other two; cases, the information now in hand, either due to. configuration or fragility aspects, should be adequate for the purposes of-this margins - analysis.- Concerning the -internals and CRDMs, the comment was made that Combustion Engineering's cooperation has -

been outstanding. ~

9) David Moore of EI, in reply to Peer Review Group questions, '

' discussed how his analysis group is coping with Groun B ')

functions, especially those items needed to support long-term heat ~ removal . - He provided.a rationale for his approach, which '

will be the subject of later review by the Peer Review Group. He then discussed in more detail the treatment of non-seismic failures,- with an emphasis on those that might compromise both redundant trains of some function. The question of how to combine these' failures with seismic-induced failures in a HCLPF '

.. analysis was covered, but not resolved. What approach to take j

remains an open questien, and the NRC Expert Panel's guidance on l this subject is inadequate.

The Peer Review Group discussed a problem with incorporating non-

seismic failures after an earthquake, if their incorporation can

, change the HCLPF level found. The problem arises if the way they

affect post-earthquake plant response at the SSE ' level is

) identical to the way they affect plant response -near the HCLPF

level or near the margin-review-earthquake level; in this case, '

! their actual effect on ' plant seismic margin' is minor. This issue will require more discussion in the future.

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10) There was further discussion of how the' comparison between CDFM and fragilities methods for HCLPF determination will be accomplished. It is recognized that the EQE effort in this project will not extend to CDFM-fragilities methodological comparisons beyond those few presented to the Peer Review Group at this meeting. There is a continuing need for a more thorough way to address this issue, which the Peer Review Group will undoubtedly comment on further later on.- It is likely that the NRC Expert Panel may need to give this issue much more careful thought after this Maine Yankee review has been completed.

11) lohn Reed asked a question of the NRC staff whose answer was not fully covered, since the NRC staff hazard experts were not present. The question concerned exactly what was intended by NRC staff in their choice of the margin review earthquake being used in the Maine Yankee analysis. After some discussion, it was decided that it would be assumed that the median NUREG/CR-0098 spectrum anchored to 0.30 g ZPA represented a uniform hazard spectrum at thef/4 % confidence level. NRC staff will attempt to obtain some clarification on this issue soon.

12) James Thomas raised a general question of how systems interactions aspects should be dealt with in the analysis, such as when a valve may hit a support during strong earthquake motion. Some generic guidance is needed to provide analysts with an acceptable approach, which should be usable in most cases without doing a detailed and expensive calculation. This aspect was not resolved in the meeting, but will be given further thought.

OVERVIEW COMMENT:

It is the broad consensus of the Peer Review Group that the Maine i

Yankee trail margins, review project is being accomplished so far with acceptable technical competence. In the course of its review, the Review Group discussed several technical issues that have been subjects of continuing difficulty in the analysis, and in some cases these difficulties may not be resolved during this trial margins review project. The Peer Review Group recognizes that one key objective of this trial review is to uncover such issues, especially methodological issues or issues of inadequate data. Its overview comment is that the analysis team, including 6

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e LLNL, EI International, and EQE experts, is carrying out a fully acceptable analysis so far, within the constraints of the project scope and subject to . the comments in the detailed ' discussion above.

The Peer Review Group looks forward to further interactions as the analysis proceeds through a second walkdown and then to final analysis and documentation of the project results.

That completes this report and minutes.

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Robert J. B dnitz Chairman, Peer Review Group i .

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ATTACHP.ENT 8 AGENDA Seismic Margins Program Peer Review Group Meeting San Francisco Airport Clarion Hotel September 30,1986 9:00 a.m. Introductions Budnitz/Murray 9:10 a.m. Briefing on NRC Working Group Meeting Guzy/ Anderson 9:30 a.m. Walkdown Summary . Ravindra 10:00 a.m. Systems Summary Moore 11:00 a.m. Briefing on EPRI Program Kassawara 12:00 noon Lunch 1:00 p.m. Fragility Summary llCLPF Comparisons liardy/Hashimoto Tank Methodology Hashimoto 3:00 p.m. Important Open Issues Batteries . Hardy Internals /CRDM Hardy Threaded Fire Water Piping Hardy 5:00 p.m. Report Outline Murray Second Plant Walkdown Schedule 6:00 p.m. Adjourn t g

, . ATTACHMENT C.

SEISMIC MARGINS PROGRAM Tentative Schedule September 23,1986 Federal Express mailing to Peer Review Group September 30,1986 Peer Review Group meeting at San Francisco Airport Clarion Hotel October 1,1986 Analysis Team meeting at San Francisco Airport Clarion Hotel October 22,1986 Analysis Team meeting at Energy Incorporated, Kent, Washington November 10,1986 Second pre-walkdown status summary Federal Express package November 17-19, 1986 Analysis Team second plant walkdown at Maine Yankee.

November 18-19, 1986 Peer Review Group meeting and additional walkdown at Maine Yankee December 8,1986 Preliminary plant HCLPF available December 10-12, 1986 Possible exchange meeting with EPRI and Analysis Team meeting (most participants will be at the Symposium on Current Issues Related to Nuclear Power Plant Structures, Equipment and Piping to be held at North Carolina State, December 10-12, 1986).

-January 1987 Briefing at the NRC on program and results

- February 1987 Draft (inal report submitted to the NRC O

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