ML19347C799

AO 50-219/74/5:on 740116,MSIV NS04A Failed to Meet Allowable Leakage Requirement.Caused by Failure of Packing Ground Valve Shaft.Valve Shaft Repacked & Valve Retested Successfully

ML19347C799
Person / Time
Site:	Oyster Creek
Issue date:	01/25/1974
From:	JERSEY CENTRAL POWER & LIGHT CO.
To:
References
AO-50-219-74-5, NUDOCS 8103040567
Download: ML19347C799 (2)

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OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74/5 Report Date:

January 25, 1974 Occurrence Date:

January 16, 1974 Identification of Occurrence:

Violation of the Technical Specifications, paragraph 4.5.F.1.d, failure of Main Steam Isolation Valve NS04A to meet the allowable leakage re-quirements . This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraphs 1.15D 6 E.

Conditions Prior to Occurrence:

The plant was shut down with the reactor coolant less than 212 F and the reactor mode switch in " Refuel".

Description of Occurrence:

It was necessary to operate NSO4A in order to provide adequate ventilation of the reactor vessel while performing maintenance work on Electromatic Relief Valve NR-108-D after the plant shutdown. Valve NS04A, therefore, was not tested in the "as found" condition after initial closure.

1447 - Leak rate test on Main Steam Isolation Valve NSO4A began.

1517 - Leak rate test on Main Steam Isolation Valve NS04A ended.

Leakage rate was 31.7 SCFil, corrected to 20 psi. The maximum allowable leakage rate is 9.945 SCFli, as required by Technical Specifications, paragraph 4.5.F.1.d.

Apparent Cause of Occurrence:

The cause of this occurrence is attributed to component failure.

After checking the test assembly and the components of the MSIV, it was determined that the packing around the valve shaft was the cause of the excessive leak rate.

Analysis of Occurrence:

The safety significance of the failure of NSO4A to pass the leakage rate test was a loss of redundancy in an engineered safety feature designed to minimize the release of fission products under design bases accident conditions.

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Abnormal Occurrence Report No. S0-219/74/S Page 2 Corrective Action:

The valve shaft was repacked and the valve was retested successfully.

NS03A was also retested to insure that it had an acceptable Icak rate, since its test assumes that' the valve NS04A has negligible leakage.

The retest of NS03A indicated no detectable Icakage, b5IV NSO4A has been selected to undergo a complete preventative maintenance inspection during the refueling outage presently scheduled for April'1974.

Failure Data:

The valve stem packing on NSO4A failed on September 27,1973 '(letter to Mr. A. Giambusso from Mr. D. A. Ross, dated October 12, 1973). At that time, the valve was repacked and subsequently passed its leak rate test.

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