ML19324B379
| ML19324B379 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 10/27/1989 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CON-NRC-89-134 GL-88-20, VPNPD-89-565, NUDOCS 8911060177 | |
| Download: ML19324B379 (4) | |
Text
l 9; Wisconsin:
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TElectnc POWER COMPANY
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231 W McNgorg Ro Sax 2046. Wwoukee.WI $3201 1414)221-2345 JVPNPD 565 NRC-8 9-134 79
' October 27, 1989 N U'.
S.' NUCLEAR REGULATORY COMMISSION Document Control Desk
- Mail Station Pl-137 o
- Washington, D.C.
20555 Gentlemen:
DOCKET NOS. 50-266 AND 50-301'
. RESPONSE TO GENERIC LETTER NO. 88-20 INDIVIDUAL PLANT EXAMINATION FOR SEVERE ACCIDENT VULNERABILITIES
- POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 NRC Generic Letter No. 88-20, " Individual Plant Examination for Severe Accident Vulnerabilities, 10 CFR 50.54(f)," directed that all' licensees respond within 60 days of receipt of the final guidance documents with their proposed programs for completing the Individual Plant Examination (IPE).
The program description should' identify the method and approash. selected for performing the IPE and identify the schedule for completing the program and providing the results to NRC staff.
The final guidance document, NUREG-1335, Individual Plant Examination Guidance Document,.was issued by the NRC on September 1,
.1989.
DESCRIPTION OF METHOD In order.to comply with the directions'of the generic letter, Wisconsin Electric has electeu to use'the Probabilistic Risk f.ssessment (PRA) methodology as identified in NUREG/CR-2300, PRA Procedures Guide.
A freeze date of March 1, 1989, was selected for the plant design to be modeled with two exceptions:
the switchgear room bypass modification committed to be installed by January 1991 for uompliance with 10 CFR 50 Appendix R, and the associated 13.8kV electrical system modifications.
We will be conducting a detailed Level 1 and a limited-scope Level 2
'PRA on Unit 1 including typical internal initiators and internal flooding.
The Unit 2 PRA will consist of a detailed review of differencets between the units and incorporation of significant differenceu, if any, into a Unit 2 analysis.
Lessons learned from the limited-scope PRA of Point Beach performed by Sandia National 8911060177 891027 5 0\\
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Laboratories for the NRC (NUREG/CR-4450) and updated by EPRI in NSAC-ll3 as part of the shutdown decay heat removal study (Unresolved
' Safety Issue A-45) will be incorporated into this new FRA.
.EI International Inc.-(EI) has been contracted by Wisconsin Electric to assist in the performance of the PRA.
EI is providing software, technology transfer, and technical support to Wisconsin Electric in
' performance of the PRA.
EI has previously performed PRA's for the Salem and Brunswick nuclear plants.
Wisconsin Electric personnel are involved in the PRA to the maximum extent possible through a team of.three engineers responsible for the
- study.
Two additional engineers from different sections in the Nuclear Power Department are expected to provide an independent review
-function.
In addition, Point Beach operations group personnel wil: be involved in the review of selected parts of the study (e.g.,
system fault trees).
Since WE does not currently possess significant PRA expertise in-house, we intend to use an additional outside consultant j;
to provide an in-process independent review of our IPE methodology, i
rather than the in-house review of methodology requested in the Generic Letter.
..The WE IPE methodology involves the use of small event trees
.(primarily systemic) and large fault trees.
The event tree and fault tree logic will be solved using an EI, PC-based PRA Workstation, which uses'the SETS fault tree analysis code originally developed by Sandia.
1 Templates or support system states'will not be used for the fault j
trees.
Plant damage bins will be defined to include all accident j
sequences.
Dependent failure analysis will be done using the multiple R
greek letter method.
Human reliability analysir. will use the perform-i ance shaping factor method documented in NUREG-1278, Handbook for F
Human Reliability, supplemented _with procedure walk-throughs and talk-i throughs with plant operators as a propriate.
A referenced generic i
p data base will be combined with plant-specific or recent industry data as appropriate for component failure rates, using Bayesian procedures.
l Importance and uncertainty analyses will be performed using the TEMAC l
and LHS codes, respectively, also developed by Sandia.
The limited Level 2 analysis will utilize comparative analysis with similar plants for the containment event tree design and quantifica-tion, and for determination of containment failure modes.
The best estimate probabilities of the core damage states from the Level 1 PRA will be used in the quantification of the CETs.
The results will be given in terms of the magnitude, frequency and timing of the different source term release bins, the dominant contributors to the significant releases, dnd the important uncertainties.
Wisconsin Electiic has recently joined the MAAP Users Group and expects to use the MAAP computer code for sensitivity studies.
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NRC Document Control Desk October 27, 1989 Page 3 1
MILESTO*iES AND SCHEDULE The-attachment to this letter provides the milestone schedule for the i
Point Beach Nuclear Plant IPE response.
The Point Beach Nuclear Plant limited Level 2 PRA should be completed by March, 1991 for both Units.
Our evaluation of plant-specific vulnerabilities and possible measures to address'them, as well as a review of outstanding NRC Unresolved and Generic Safety Issues, is expected to take an additional twelve months.
If Severe Accident Management guidelines are-available at if that time, we would also expect to incorporate them into the evalua-U tion.
Therefore, we plan to submit a summary report of the IPE j.
results for Point Beach in accordance with the guidance in NUREG-1335 by March 31, 1992.
t We would be pleased to answer any questions you may have regarding the above information, j
Very truly yours,
[
C. W. Fay Vice President Nuclear Pt::cr J
Attachment Copy to NRC Regional Administrator, Region III NRC Resident Inspector Subscribed an.d sworn to before me this d day of h
,1989.
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Notary Public, Stat 6 of Wisconsin My commission expires: f'- 2 7 7 6
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r PROBABILISTIC RISK ASSESSMENT MILESTONE SCHEDULE POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 Expected Date Milestone l
June 30, 1990 1.
Complete Point Beach Unit 1, Level 1 PRA.
September 30, 1990 2.
Complete Unit 2, Level 1 PRA supplement.
i March 31, 1991 3.
Complete Unit 1 and Unit 2 Limited Level 2 PRA.
March 31, 1992 4.
Complete Submittal of IPE results for Point Beach Nuclear Plant (Includes evaluation and disposition of vulnera-bilities, Severe Accident Management guidelines [if available) and USI/GSIs).
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