ML17305A358

Responds to Generic Ltr 88-20,Suppl 1 Re Proposed Program for Completion of Individual Plant Exams.Level I PRA Already Begun When Generic Ltr Published

ML17305A358
Person / Time
Site:	Palo Verde
Issue date:	10/30/1989
From:	Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
161-02550-WFC-R, 161-2550-WFC-R, GL-88-20, NUDOCS 8911070283
Download: ML17305A358 (8)

Text

ACCELERATED LTRJBUTION DEMONSATION SYSTEM c

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

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SUBJECT:

Responds to Generic Ltr 88-20,Suppl 1 re proposed program for completion of individual plant exams.

DISTRIBUTION CODE:

A001D COPIES RECEIVED:LTR

( ENCL l SIZE: 3 TITLE: OR Submittal:

General Distribution ACCESSION NBR:8911070283 DOC.DATE: 89/10/30 NOTARIZED: NO FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi AUTH.NAME AUTHOR AFFILIATION CONWAY,W.F.

Arizona Public Service Co.

(formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

D NOTES Standardized plant.

Standardized plant.

RECIPIENT ID CODE/NAME PD5 LA CHAN,T INTERNAL: ACRS NRR/DEST/ESB 8D NRR/DEST/MTB 9H NRR/DOEA/TSB 11 OC LF B FILE 01 EXTERNAL: LPDR NSIC NOTES COPIES LTTR ENCL 1

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1 RECIPIENT ID CODE/NAME PD5 PD DAVIS,M.

NRR/DEST/ADS 7E NRR/DEST/ICSB NRR/DEST/RSB 8E NUDOCS-ABSTRACT OGC/HDS1 RES/DSIR/EIB NRC PDR COPIES LTTR ENCL 1

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D NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAMEFROM DISTRIBUTION LIPID FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED:

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Arizona Public Service Company P.O. BOX 53999

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PHOENIX, ARIZONA85072<999 WILLIAMF. CONWAY EXECUTIVEVICEPRESIDENT NUCLEAR IDS 161-02550-WFC/RAB/GAM October 30, 1989 Docket No. 50-528/529/530 Document Control Desk U ~

S. Nuclear Regulatory Commission Mail Station Pl-37 Washington, D.

C.

20555

Reference:

NRC Letter to all Licensees Holding Licenses and Construction Permits for Nuclear Power Reactor Facilities, "Individual Plant Examination for Severe Accident Vulnerabilities - 10 CFR Sec.

50 '4(f)", Generic Letter No. 88-20, dated November 23, 1988

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2,

and 3

Proposed Program for Completion of IPE File:

89-052-026 In response to Generic Letter 88-20, Supplement No.

1, dated August 29,

1989, Arizona Public Service (APS) is submitting a proposed program for completion of the Individual Plant Examinations (IPE) for PVNGS.

The attached program includes (1) identification of the method and approach selected for performing the IPE, (2) description of the method to be used and (3) identification of the milestones and schedule for performing the IPE and submitting the results to the NRC.

With the exception of submittal of the final results to the

NRC, the proposed milestones may be adjusted as the IPE progresses and information obtained is-assessed.

If there are any questions regarding this submittal, please contact A. C. Rogers of my staff at (602) 371-4041.

Sincerely, WFC/RAB/GAM/jle Attachment cc:

A. C. Gehr T. J. Polich J.

B. Martin T. L. Chan M. J.

Davis 83 891030 p

PDR ADOCK 0 8911070283

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Palo Verde Nuclear Generating Station, Units I, 2, and 3

Response

to NRC.Generic Letter 88-20,Supplement No. I:

Individual Plant Examinations for Severe Accident Vulnerabi'lities Pur ose and Summar This submittal contains Arizona Public Service Company's (APS) proposed program for completing the Individual Plant Examinations (IPE) for Palo Verde Nuclear Generating Station Units 1,

2, and 3,

as requested in the August 29, 1989 Supplement No.

1 to the subject Generic Letter.

In response to Item 1. of the, Supplement, APS intends to pursue a full Level I Probabilistic Risk Assessment (PRA) in determining any significant sequence of events that could lead to core damage.

The, approach to the so called "back-end" analysis will follow the standard elements of a Level II PRA, although detailed analyses may not be done in cases where existing calculations from other plants would be applicable.

In response to Item 2. of the Supplement, the PRA methodology for Levels I and II will be based on that outlined in NUREG/CR-2300, PRA Procedures Guide, but with the intention of using applicable calculations from previous studies in the back-end analysis as recommended in Appendix A of NUREG-1335, Individual Plant Examination:

Submittal Guidance.

In response to Item 3. of the Supplement, APS is proceeding expeditiously to complete the examination process, which we currently estimate to require 8.5 man-years of additional effort, excluding internal reviews.

A realistic evaluation of the resources available to carry out the IPE leads to an estimate of Spring of 1991 for completion of the Level I effort, end of 1991 for completion of the Level II effort, and completion of the submittal package during Spring of 1992.

Further details as to approach and schedule are given in the sections that follow.

Method and A roach

. ~

APS had already begun the Level I PRA for the Palo Verde units when Generic Letter 88-20 was published.

This effort willbe continued and expanded with the modifications~ necessary to meet 'the objectives of, the Letter, using the guidance of NUREG-1335.

Since all-three Palo Verde units were built by the same Architect/Engineer (A/E) to a standardized reference

design, the Combustion Engineering System 80, most of the analyses will be carried,out once using the reference design, with unit-specific variations treated as special cases.

The detailed Level I analysis uses the small event tree/large fault tree approach.

Detailed front line and support system fault trees are being developed for the solution of functional event trees.

Sequence quantification willbe done using the SETS computer program.

Plant specific initiating events have been included in the accident sequences, and maintenance-related primary events have been quantified using plant specific data.

Internal flooding events have not been included in the on-going Level I analysis; these will be incorporated into the IPE after the quantification of all other internal event sequences is completed.

Since no Level II activities have been started, the guidance provided in Appendix A of NUREG-1335 will play an important role in shaping the Level II effort.

There are, however, some analysis issues, such as the best approach for obtaining source term values, that input from the various industry groups should help resolve.

Estimated Schedule Our estimated schedule for completion of the IPE is reflected in the following milestones:

May, 1990: Quantification of accident sequence frequencies, no internal flood initiators.,

September, 1990:

December, 1990:

April, 1991:

Quantification of accident sequence frequencies for internal flood initiators.

I Independent review of system models and results.

Identifi'cation of plant vul'nerabilities and proposed remedial action; completion of Level I analysis.

August, 1991:

October, 1991:

December, 1991:

Completion of back-end analysis.

Independent review of containment models and results.

Identification of containment vulnerabilities and proposed remedial action; completion of Level II analysis.

April, 1992:

Submittal of IPE report.

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