ML20094F467

Advises That Individual Plant Exam Completion Date Delayed from June 1992 to 921231,per Generic Ltr 88-20

ML20094F467
Person / Time
Site:	Grand Gulf
Issue date:	02/18/1992
From:	Cottle W ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-88-20, GNRO-92-00010, GNRO-92-10, NUDOCS 9202240330
Download: ML20094F467 (2)

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February 18, 1992 U.S. Nuclear Regulatory Com,31ssion Mall Station Pl-137 Washington, D.C. 20555 At t en t. ion : Document Conttol Desk

Subject:

Grand Gulf Nuclear Statinn Unit 1 Docket No. 50-416 License No. NPF-29 a Graed Gulf Nuclear St ation Individual Plant F.xam ina t ion ,

GNRO-92/00010 Gentlemen:

In c letter dated October 31, 1989 (AECM-89/0200), System Energy Resources (now Entergy Operations, Inc.), submitted the methodology and a schedule for completion of t he Grand Gulf Nuclear Stat ton (GGNS)

Individual Plant Examination 'IPE) as specified in Generic 1.etter (GL) 88-20. In that submittal, it was anticipnted that the GGNS IPC would be completed in June H92.

The purpose of this letter is to inform you that the IPE completion dat.e .

is now expected to be December 31, 1992, This schedule change is due to several factors. The original schedule was bnsed on the opinion that the GGNS IPE would be very similar to the NUREG/CR-4550 analysis of GGNS.

Ilowever, during the course of the GGNS IPE, this assumption of s.imilarity has proven to be erroneoun. At this time we estimate t hat approx imat ely 1200 sequenc s will have to be evaluated for the GGNS IPC (261 sequences were evaluated fer NUREG/CR-4550) . This large number of sequences 18 due to the additional initiators which are being evaluated for GGNS and some differen:es in accident sequence model.ing. While not all of t hese sequences will have to be quant ified due to similarit ios to other sequences, as was done in NUREC/CR-4550, this work scope is still considerably larger than or.iginally anticipated.

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t February 18. 1992

. GNRO-92/00010 page 2 of 3 In the original response to GL 88-20, we indicated the conta l an s t performance analysis or Level 2 portion of thn :06 would be j fc *ed using a methodology consistent wit h the general guidance glvoi i.

Appendix 1 of Gh 88-20. This method allows the use of a "tempie.to" approach where the utility can reference analyses performnd for a similar plant in lieu of performing new plant specific analysis for their plant.

This approach was thought to_ be appropriate for GGNS since GGNS was a reference plant f or t he NUREG-il 50 ana lys is , llowe v e r , since this initial decision was made,-Entergy has become aware thnt most utilities arn performing their own plant specific analyses (primarily with MAAp) or at least some verification of important sequences. In addition, we have also become concerned that the existing calculations may not adequately describe tbo important GGNS accident nequences since our results may i dif f er f rom the NUREG/CR-4550 work. For t hese reasons, we are considering the dovnlopment of a LAAp model for GGNS to use in our hevnl 2 analysis. We believe that this model will allow us to better understand the responso of thn plant in severn accident sequences and provido a product useful in future applications such as accident management.

Should you have any questions please contact. James Owens at (601) 437-6483.

Yours truly, e z) Qw r r WTC/JE0/mtc cc: Mr._D. C. Ilintz Mr. J. L. Mathis Mr. R. B. McGonne Mr. N. S. Reynolds M r. 11. L. Thomas Mr. Stewart D. Ebneter Regional Adminiatrator U.S. Nuclear Regulatory Commission Region 11

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101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30323 Mr. i.i W. O'Connor, project Manager Office of Nuclear Reactor Regulat.fon l

i U.S. Nuclear Regulatory Commission

! Mai1 Stop 13113 Washington, D.C. 20555 G9201161/SNLICFLR - 2

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