ML20090E458

Supplemental AO 50-237/75-44:diesel Generator Failed to Start.Caused by Air Relay Valve Failure Due to Sticking O-rings.O-rings Replaced

ML20090E458
Person / Time
Site:	Dresden
Issue date:	12/17/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20090E462	List: ML20090E458 ML20090E464
References
830-75, RO-50-237-75-44, NUDOCS 8303310644
Download: ML20090E458 (2)

Text

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v (j Chicago, Illinois 60690 BBS LTR. #830-75 Dresden Nuclear Power Station RR #1 17,1975 8, 50 M.~f '?

604 Morris, 1111 nots December

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t, Mr. James G. Keppler, Regional Director C ** % ' [O.x "")! -

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SUSJECT: SUPPLEMENTAL REPORT TO LETTER DATED OCTOBER 2, 1975. ENTITLED

" UNIT-2 OlESEL GENERATOR FAILURE TO $ TART" (Report No. 50-237/

75-44)

References:

1)

Report No. 50-237/75-44 fEEILE COPY 2)

Drawing No. M173 REPORT NUMBER:

50-237/75-44A REPORT DATE:

December 17, 1975' FACILITY:

Dresden Nuclear Power Station, Morris, 111.

INTRODUCTION in the course of pursuing corrective actions specified by the original abnormal occurrence report, certain aspects of that occurrence were clarified. As a result, the following paragraphs should replace the corresponding items of report no. 50-237/75-44.

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DESIGNATION 0l> APPARENT CAUSE OF' OCCURRENCE (Component Faliure)

The apparent cause of the occurrence was failure of the air relay valve. The air relay valve piston and "0" rings exhibited abnormal stickiness.

In the past, "0" rings used for the valve piston have been off-shelf items sized to fit the "0" rings removed.

Variations in "0" ring sizes from storeroom stock may have accounted for the sluggish valve operation.

8303310644 751217 CORRECTIVE ACTION PDR ADOCK 05000237 S

PDR The diesel generator was removed from service, and the entire air start system was inspected for obstructions. The air relay valve was subsequently dismantled, and the sticking "0" rings were replaced with the proper components.

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Mr. James G. K;ppler ' 0:cember 17, 1975,,

Upon reassembly, the. valve was operated satisfactorily several times. The diesel generator has been started at least three times since the valve was re-installed.

No starting difficulties have been noted.

f "0" rings for the specific valve have been ordered directly from the vendor and will be stocked, safety-related items.

FAILURE DATA The air relay valve is a 2" air-operated valve manufactured by Graham-White Mfg.

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