ML20107H885
| ML20107H885 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood, 05000000 |
| Issue date: | 02/15/1985 |
| From: | Danni Smith COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 85-01, 85-1, 9770N, NUDOCS 8502270310 | |
| Download: ML20107H885 (2) | |
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Te Commonwealth Edison One First Nation ~l Plazi Chic:go. Illinois I
Address Reply to: Post Othee Box 767 Chicago, Illinois 60690 February 15, 1985 Mr. James G. Keppler Regional Administrator U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137
Subject:
Bryon Station Units 1 and 2 Braidwood Station Units 1 and 2 i
10 CFR 50.55(e) No. 85-01 Report Westinghouse 10 Amp Breaker Low Interrupt Rating j
NRC Docket Nos. 50-454/455 and 50-456/457
Dear Mr. Keppler:
i On January 17, 1985, Commonwealth Edison Company notified your office of a potential deficiency reportable pursuant to 10 CFR l
50.55(e) regarding 10 amp Motor Control Center (MCC) breakers with low interrupt ratings.
This letter provides information to fulfill the thirty-day reporting requirement and is considered a final report.
DESCRIPTION OF DEFICIENCY The 480 volt, 10 amp breakers supplied with the Westinghouse Motor Control Centers did not meet our Specification F/L 2755.
The breakers have an interrupting rating of 4000 to 5000 amps.
The rating should have been equal to or above the 14,000 amp fault current capability of the 480 Volt MCC bus.
The requirement was stated in the specification.
ANALYSIS OF THE SAFETY IMPLICATIONS Depending upon the magnitude and duration of the fault current and time-current characteristic of the backup breaker, electrical penetration feed-throughs intitally protected by the 10 amp breaker may not be adequately protected by the back-up breaker.
This could possibly result in a breakdown of the electrical or pressure boundary of the electrical penetration.
Tripping of the back-up breaker would also result in de-energizing the entire Motor Control Center and any safety related equipment fed from this MCC.
Such an action would prevent this equipment from performing its safety related functions.
8502270310 850215
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%r CORRECTIVE' ACTION TAKEN All ofethe effected safety-related breakers on Byron Unit 1 were replaced by October 18, 1984.
The effected breakers on Byron Unit 2 and Braidwood Unit 1 and Unit 2 will be replaced before fuel load of the respective unit.
Please address.any questions that you or'your staff may have concerning this matter to this office.
er truly yotirs,
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%v David H. Smith Nuclear Licensing Administrator
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NRC Resident Inspector - Byron NRC Resident Inspector - Braidwood Director of Inspection and Enforcement U.S.' Nuclear Regulatory Commission Washington, DC 20555 9770N
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