PNO-III-96-064, on 961023,shutdown for Evaluation of Environ Qualification Data Made.Licensee Performed Preliminary Assessment of Effect of Higher than Anticipated Temp Profile on safety-related Electrical Equipment Located

PNO-III-96-064:on 961023,shutdown for Evaluation of Environ Qualification Data Made.Licensee Performed Preliminary Assessment of Effect of Higher than Anticipated Temp Profile on safety-related Electrical Equipment Located

ML20134D518
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	10/24/1996
From:	Frederick Brown, Miller L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-96-064, PNO-III-96-64, NUDOCS 9610250042
Download: ML20134D518 (1)

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October 24. 1996 p PRE'LIMINARY NOTIFICATION OF EVENT CR UNUSUAL OCCURRENCE PNO-III-96-064 >

This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation and is basically all that is

known by Region III staff (Lisle. Illinois) on this date.

Facility Licensee Emergency Classification Consumers Power Co. Notification of Unusual Event l Big Rock Point 1 Alert

! Charlevoix. Michigan Site Area Emergency ,

Dockets: 50-155 General Emergency i X Not Applicable l

Subject:

SHUTDOWN FOR EVALUATION OF. ENVIRONMENTAL QUALIFICATION DATA  !

! On October 23. 1996, the Big Rock Point Nuclear Station was shut 'down l because of recently identified information indicating that it is outside i its design basis for environmental qualification temperature profiles  ;

during a postulated "large break" loss of cooling accident (LOCA).  ;

Big Rock Point's program for establishing that safety-related electrical l equipment would operate under the environmental conditions experienced during a large break LOCA (main steam line break) was based on a design maximum temperature of 260 degrees F. inside containment. This design  !

basis temperature was selected based upon computer modeling of the

effects of a spectrum of LOCAs, Plant staff recently ran a new computer i simulation of a large break LOCA which indicated that the maximum temperature inside containment would reach approximately 325 degrees F.

On October 22. 1996, an error in the original computer model was  ;

identified by plant staff who were trying to resolve.the difference in  !

temperature profile results. '

The licensee has performed a preliminary assessment of the effect of the ,

higher than anticipated temperature profile on safety-related electrical '

equipment located inside containment. Based u)on this assessment, the-  !

licensee considers all required equipment to 3e operable, but decided to shut the plant down as a prudent compensatory action while additional evaluations are being performed. .

! The shutdown is expected to last about a week. The resident inspectors j will monitor the licensee's activities during the shutdown.

The State of Michigan will be notified. The information in this Preliminary Notification have been discussed with the licensee.

The resident inspectors were informed of the licensee's findings and plans to shut down at 10:15 a.m. CDT on October 23. 1996. This information is current as of 8 a.m. on October 24. 1996.

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Contact:

FREDERICK BROWN LEWIS MILLER (630)829-9620 (630)829-9629 i

9610250042 961024 NO-I 96-064 PDR 250004

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