ML20062G900

Interim Deficiency Rept Re Emergency Diesel Generator Field Relay Failure.Initially Reported on 820702.One Contact on Relay 14FX Found Fused Closed.Relay Replaced.Final Rept Expected by 820902

ML20062G900
Person / Time
Site:	Byron, Braidwood, 05000000
Issue date:	08/02/1982
From:	Tramm T COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
10CFR-050.55E, 10CFR-50.55E, 4643N, NUDOCS 8208130223
Download: ML20062G900 (2)

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x Commonwealth Edison

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( O 7 Addrtss Arply tr Post Offico Box 7@

v/ Chicago, Illinois 60690 August 2, 1982 Mr. James G. Keppler, Regional Administrator Directorate of Inspection and Enforcement - Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137

Subject:

Byron Station Units 1 and 2 Braidwood Station Units 1 and 2 Emergency Diesel Generator Field Relay Failure NRC Docket Nos. 50-454, 50-455, 50-456 and 50-457

Dear Mr. Keppler:

On July 2, 1982 Commonwealth Edison Company notified Mr. J.

Hines of your office of a diesel generator relay deficiency which is reportable pursuant to 50.55(e). For your tracking purposes, this deficiency is numbered 82-04 for Byron Station and 82-03 for

Braidwood Station. This is an interim report. The final report will be submitted by September 2, 1982.

Description of Deficiency During testing of Byron emergency diesel generator 1B it was discovered that one of the contacts on relay 14FX was fused closed. This caused the field flashing circuit to remain energized after the diesel generator had been stopped. That relay was replaced and the test resumed.

Further investigation revealed severe burning and pitting of the contacts on relay 14FRX (the backup to relay 14FX) and the contacts on the voltage sensing relays in the field flashing circuits of both Byron 1 emergency diesel generators. It appears

, that the contacts do not have adequate DC interrupting capability in these applications.

Analysis of Safety Implications The failure of one field flashing relay, either 14FX or 14FRX should not prevent proper operation of the diesel generator.

Failure of both relays would prevent field flashing and would render the diesei inoperable. If the contacts in either relay fused closed, the field would remain energized while the diesel generator was stopped. This would eventually result in degradation of the field winding.

8208130223 B20802 ~2 UI7 PDR 6 ADOCK 05000454 PDR 0 %'

4 97

J. G. Keppler August 2, 1982

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Corrective Action Taken The defective relay has been replaced with one having heavier contacts. Field voltage is being monitored to assure correct relay operation when the diesel generator is stopped. The~

supplier, (Cooper Energy Services) has been contacted for their recommendation on a permanent fix.

Please address questions regrarding this matter to this Very truly yours, fif&v T. R. Tramm Nuclear Licensing Administrator 1m cc: Director of Inspection

.and Enforcement 4643N l'

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