ML20059N151

Provides Revised Program Description Identifying Method & Selected Approach for Performing Individual Plant Exams for Severe Accident Vulnerabilities

ML20059N151
Person / Time
Site:	Point Beach
Issue date:	09/28/1990
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-90-097, CON-NRC-90-97 VPNPD-90-416, NUDOCS 9010100166
Download: ML20059N151 (5)

Text

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Wisconsin  ;

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Electnc 1 y .

[ POWER COMPAW .;

231 W tactagon, PO Box 2046. Mdwoukee.Wi 53201 (414)f 21-2345 i

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VPNPD-90-416 4

. . NRC-90-097:

e e W September'28, 1990 -i

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U. S. NUCLEAR REGULATORY COMMISSION Documchc Control Desk j

• Mall Station P1-137 n' ' Washington, D.- C.--'20555

, Gentlemen

i DOCKETS 50-266 AND 50-301

CONTINUATION OF INDIVIDUAL PLANT,~ EXAMINATIONS FOR SEVJRE ACCIDENT VULNERABILITIES POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2

'NRC Generic Letter-88-20, " Individual Plant Examination for j LSevere Accident; Vulnerabilities, 10 CFR 50.54 (f)", directed that s

'allnlicenseesfrespond within sixty' days of receipt of the final  ;

guidance' documents:with their proposed programs for completing

-the: Individual Plant-Examination (IPE). . Wisconsin Electric responded byEletter (VPNPD-89-565, NRC-89-134) dated October 27, <

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The letter. included a program. description that identified '

'the' method and approach selected for performing the.IPE. The schedule'forfcompleting tt<e program and? providing the results to the NRC staff 1was1also. included.:

. Wisconsin Electric was notified in March 1990 that the contractor' a"

, helping in the work, EI International, could not. complete the Y work!and had' filed for protection under Chapter 11 of the Bankruptcy; Laws. Wisconsin Electric prepared a revised L specification and issued a request for quotations to three +

L . vendors;toiprovide. support for continuation of our IPE. The L vendors responded; the: bids were evaluated; and bid meetings were R held with the two preferred vendors. Westinghouse Electric Corporation was the successful vendor and on August 22, 1990, a contract was awarded to Westinghouse for this work. The work.

L, .with Westinghouse startet o.1 September 5, 1990, with a project i L kickoff meeting. '

The-original vendor's failure to perform and the subsequent change in vendors have had a significant impact on the original schedule. The' program description ~has also changed slightly. 1 This " letter provides the revised pr<, gram description identifying l C12G \\

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ll NRC Document Control-Desk ',

September _ 28, 1990 Page-2 l

D tc the method and selected approach for performing the IPE and the I: revised = schedule.

1' DESCRIPTION OF METHOD Wisconsin Electric will still be using the Probabilistic Risk Ax -ment-(PRA) methodology as identified in NUREG/CR-2300, EEA Procedures Guide. A new freeze date of September.5, 1990 was,.

however, selected for the plant design to be modeled with the same two exceptions: The switchgear. room bypass modification committed to be installed by January 1991 for compliance with 10 p CFR 50 Appendix R and the. associated 13.8 kV electrical system

y. modifications will be included in our PRA model.  ;

1 As before, we will-be conducting a detailed Level 1 and a limited-scope Level'2 PRA~on' Point Beach Unit 1 including typical internal initiators and internal flooding. The Unit 2EPRA will~

L consist of a detailed review of differences between the units and d L incorporation of significant differences, if any, into.a Unit 2 analysis.- Lessons'1 earned from the limited-scope PRA of Point Beach performed by Sandia National Laboratories for the NRC (NUREG/CR-4458)~and updated by EPRI in NSAC-113:as part of the p' shurdown decay heat removal' study (Unresolved' Safety Issue A-45) f will be incorporated into this new PRA.

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Westinghouse Electric Corporation,: including its subsidiary Fauske and-Associates, Inc. (FAI),1has.been contracted by Wisconsin Electric to help in the performance of the PRA. .

Westinghouse is providingfsoftware, technology transfer (including training), and technichi support to Wisconsin Electric p in performance of the PRA. Westinghouse and FAI have previously (

L performed PRA's for several nuclear plants.

L 1 Wisconsin Electric personnel are still involved in the PRA, to L the' maximum extent possible, through a' team of at least'two engineers responsible for the study. In addition, Point Beach H -Operations Group personnel will be involved in the review of i p selected parts.of the study (e.g., system f ault trees) . - Since WE 4 does not currently possess significant'PRA expertise in house, we L, intend to use an additional outside consultant to provide an in- i

. process independent review of our IPE methodology instead of.the in-house review of methodology requested in the Generic Letter.

I The WE IPE methodology still involves the use of small event trees (primarily systemic) and large fault trees. The event tree and fault tree logic, however, will now be solved usjng Westinghouse procedures and PC-based software. The Level 1 PRA will'use the fault tree linking method as described du NUREG/CR~

2300 and NUREG/CR-2815.

I 4:1s: 1N NRCJDocument Control Desk )

September 28, 1990 l

.Page'3 Plant dainage bins will be defined to include all accident - R sequences. Parametric modeling of dependent failures will still  ;

be done using the multiple Greek letter method. Sensitivity and

importance determinations will again be made by determining Fussel-Vesely importance factors for critical systems and components. Human reliability analysis will now use the THERP methodology, supplemented with procedure walk-throughs anditalk-throughs'with plant operators as appropriate. A referenced '

generic data base will be combined with plant-r acific or recent -

industry data as appropriate for component failu.. tates, using

• Bayesian procedures as before. The uncertainty analysis will still be performed using the Sandia-developed TEMAC and LHS codes.-  !

L The limited Level:2 analysis will e.camine the physical processes associated with the dominant accident se;uences-and the response of the Point Beach containment and containment systems.

Containment event trees will be devel ped to address containment. 1 isolation, bypass, containment'systemu, long-term decay heat-

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removal capability,'and phenomenological issues including uncertainties.- The containment analysis will involve hand calculations'. supplemented as necessary w).tn detailed calculations by Wisconsin Electric, using the MAAP code with Point Beach-specific data. The containment event trees will include sufficient nodes to provide the capability to model complex sequences involving phenomena that occur after the onset of core 3 damage. The, unresolved technical issues between IDCOR and the  ;

.NRC will:be addressed in the Point Beach containment analysis in preparing and quantifying the containment event trees.

MILESTONES AND SCHEDULE The attachment to this_ letter givesithe milestone schedule for 1 the Point Beach Nuclear Plant IPE response. The Point Beach Nuclear Plant full-scope Level-1 and limited-scope Level 2 PRA-should be completed by March 1992'for both? units. Our evaluation af plant-specific vulnerabilities and possible measures to address'them and a review of outstanding NRC Unresolved and Generic Safety Issues should take an additional nine months.- If Severe Accident Management Guidelines are available at that time, we also expect to incorporate them into the evaluation. We, thereforW, plan to submit a summary report of the IPE results for Point Du /h according to the guidance in NUREG-1335 by Decembe 1, 1992. Although this submittal schedule extends four months beyond the three-year schedule requested in the Generic Letter .n view of our difficulties with the original contractor, we believe that this extension to necessary to perform the comprehensive, high-quality IPE that both WE and the NRC staff desire. If this schedule extension is not acceptable to the NPC

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LNRC Document Control Desk i September 28, 1990 j Page 4 l l

staff, p1' ease 1 notify:us as-soon as'possible. We also reserve the l

,. .right to recansider this schedule in light of the anticipated l Generic Letter requiring an IPE for external events.- '

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Wo would be pleased to answer any questions you may have about the-above information.

I Very trulyf ours, (h6l L. C. Ti. Fy . .

Vice President Nuclear Power.

' Attachment Copies-to NRC Regional' Administrator, Region III NRC Resident Inspector-Subscribed this pgd dayand of Sswor Lto before me h l;,.3__,

, 1990.

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Notary.Public, State'6fEWisconsin 4

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g EE9 6 REVISED MILESTONE SCHEDULr, i P0 INT BEACH NUCLEAR PLANT. UNIT 5 1 AND 2 .1 n 1

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igpicted Date

. Milestone- ,  ;

-December 1991 - 1. Complete Point Beach Units 1 and 2, Full-Scope, Level 1 PRA.- >

l-( (Includes internal flooding analysis).

4 March 1992 2. Complete Units'1 and 2 Limited-ii Scope, level 2 PRA.

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December 1992 3. Complete Submittal of IPE results. l M- ,

yri" for Point Beach Nuclear. Plant ~ i i

(includes evaluation and disposition of vulnerabilities, .

4- Severe. Accident Management p

W guidelines [if available) and. I u.

USI/GSIs).

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