ML17332A581

Forwards IPE of External Events Response to NRC Audit Concerns & RAI

ML17332A581
Person / Time
Site:	Cook
Issue date:	02/15/1995
From:	Fitzpatrick E INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17332A582	List: ML17332A581 ML17332A584 ML17332A585 ML17332A586
References
AEP:NRC:1082K, NUDOCS 9502280019
Download: ML17332A581 (5)

Text

PRI(3RI EY 1

ACCELERATED RIDS PROCESSING)

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9502280019 DOC.DATE: 95/02/15 NOTARIZED-NO DOCKET FACIL:50-'315 Donald C.

Cook Nuclear Power Plant, Unit 1, Indiana M

05000315 50-316 Donald C.

Cook Nuclear Power Plant, Unit 2, Indiana M

05000316 AUTH.NAME AUTHOR AFFILIATION FITZPATRICK,E.

Indiana Michigan Power Co.

(formerly Indiana

& Michigan Ele RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk) +~~

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SUBJECT:

Forwards IPE of external events response to NRC audit gsVw&~

concerns 6 RAI.

DISTRIBUTION CODE:

A011D COPIES RECEIVED: LTR J ENCLf SIZE: iS +s ~

0 TITLE: Generic Ltr 88-20 re Individual Plant Evaluations NOTES RECIPIENT ID CODE/NAME PD3-1 PD INTERNAL:~ACR HOUSTON M

FILE CE~EK 0'1 NRR/DRPE/PD1-4 RES/DSIR/SAIB/B RGN 1 RGN 3

EXTERNAL: NOAC COPIES LTTR ENCL 1

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1 RECIPIENT ID CODE/NAME HICKMAN,J AEOD/SPD/RRAB NRR/DOPS/OECB NRR/DSSA/SPSB RES/SAIB RGN 2

RGN 4

NRC PDR COPIES LTTR ENCL 1

1 1

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YOTE TO ALL"RIDS" RECIPIEYTS:

PLEASE HELP US TO RFDUCE KVASTE!COYTACTTIIE DOCL'ifEYTCONTROL DESK, ROOM Pl-37 (EXT. 504-2033 ) TO ELlhf!NATE YOI.'R XAifE FROil DIS'I'RIIIUTIOYLIS'I'S I'OR DOCI. h IEi'I'S YOL'OY"I'LZI'.D!

TOTAL NUMBER OF COPIES REQUIRED:

LTTR 24 ENCL 24

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Indiana Michigan Power Company P.O. Box 16631 Coiumbus, OH 43216 FI February 15, 1995 AEP:NRC:1082K Docket Nos.:

50-315 50-316 U. S. Nuclear Regulatory Commission ATTN:

Document Control Desk Vashington, D; C'."

20555 Gentlemen:

Donald C.

Cook Nuclear Plant Units 1 and 2

INDIVIDUALPLANT EXAMINATIONOF EXTERNAL EVENTS

RESPONSE

TO NRC AUDIT CONCERNS AND REQUEST FOR ADDITIONALINFORMATION In an audit of the individual plant examination for external events by the NRC staff on July 26 to 28, 1994, the NRC identified several concerns with the methods used to perform the fire and seismic portions of the analysis.

Draft revisions to these analyses were developed and presented to the NRC staff during a

meeting on October 25, 1994. At that time, the staff felt that many of the original concerns were substantially addressed;

however, some follow up information was requested in a

letter dated November 14, 1994.

This letter provides the completed fire and seismic probabilistic risk assessment analyses.

Attachment 1 summarizes the NRC concerns and questions'n"these'n'alyses, with a'rief 'suinmary of how each concern or question is addressed in the analyses.

Attachment 2 is the revised fire probabilistic risk assessment, and Attachment 3 is an addendum to the seismic probabilistic risk assessment.

Attachment 4 contains supporting seismic fragility calculations requested by the NRC in the November 14, 1994, letter.

The fire probabilistic risk assessment revision resulted in a

change in core damage frequency from 1.61E-07/yr to 3.76E-06/yr.

This represents an increase in the fire risk magnitude relative to total core damage frequency from 0.2% to 6.0$.

This increase is due to the reevaluation of items such as the fire initiation frequency and the impact of initiating events on each of the fire zones analyzed.

Even though there was an increase in core damage frequency, no new vulnerabilities were identified as a result of the revised fire probabilistic risk assessment.

9502280019 9504i5 PDR ADQCK 05000315 P

PDR

U. S. Nuclear Regulatory Commission Page 2

AEP'NRC:1082K The revised seismic probabilistic risk assessment estimates the total core damage frequency as 3.17E-06/yr, an 80% reduction from the original analysis value of 1.83E-05/yr.

This is primarily due to the conservatism that was removed from the seismic fragility calculations and the subdivision of the second and third seismic intervals.

Although both of these changes were requested by the NRC in order to identify vulnerabilities that might have been hidden by the conservative

analyses, no

new, significant contributors or re-ranking were identified in the revised analysis.

Sincerely, HJ E.

E. Fitzpatrick Vice President eh Attachments cc:

A. A. Blind G. Charnoff J.

B; Martin-"'"

NFEM Section Chief NRC Resident Inspector

- Bridgman J.

R. Padgett

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