ML20039B283

RO 50-219/81-65-01P:on 811203 & 09,two Isolation Valves for Isolation Condenser Sys Found to Have Defects & Valve V-14-30 Found Inoperable.Damaged Threads in Lower Part of Stem Nut Repaired.Cause Under Investigation

ML20039B283
Person / Time
Site:	Oyster Creek
Issue date:	12/10/1981
From:	Carroll J JERSEY CENTRAL POWER & LIGHT CO.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
RO-81-65-01P, RO-81-65-1P, NUDOCS 8112220491
Download: ML20039B283 (3)

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_CcctL21ed Dy Y & y Jh~]g' IO: Ronald Haynes Directorate of Regulatory Operations Region I 631 Park Avenue i King of Prussia, Pennsylvania 19406 FInt: Jersey Central Power & Light Cmpany Oyster Creek Nuclear Generating Station Docket No. 50-219 Forked River, New Jersey 08731 SUIUDCT: BGportable Occurrence Report No. 50-219/81-65/0lP The following is a preliminary report being subnitted in cxxtpliance with the Technical Specifications, paragraphs 6.9.2.,a J? . r, 6.9.2.,b,2.

$Y - <f IWCLt;;;.g t; p - IS0lk Preliminary Approval: hD

?8?N rn.

. T. Carroll, cting Directo ster Creek Director (2)

Office of Managenent Inforniation and Program Control U.S. Nuclear Regulatory Cm mission Washington, D. C. 20555 NRC Resident Inspector (1)

Oyster Creek Nuclear Generating Station

-Forked River, N. J.

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A 8112220491 0112: 0" /

PDR ADOCK 05009219 6 PDR

. m OYSTER CREEK NUCLEAR GENERATING STATICN Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/81-65-OlP Report Date Deceuber 10, 1981 Occurrence Date D e r 9, 1981 Identification of Occurrence Limitorque operators for two isolation valves for the Isolation Condenser Systen were found to have defects which did affect the operability of one valve and could affect those on other systens which perform a reactor coolant pressure boundary and primary contairinent isolation function.

'Itus is considered to be a reportable occurrence in accordance with Section 6.9.2.,a,9 of the Oyster Creek 'Ibcnnical Specifications.

Additionally, valve V-14-30 in the Isolation Condenser Systan was found to be inoperable, and failed to fully close when subjected to a close signal. 'Ihis is determined to be operation in a degraded node pennitted by Section 3.8.C and Table 3.1.1,H.

This is considered to be a reportable occurrence in accordance with Section 6.9.2.,b,2 of the Oyster Creek Technical Specifications.'

Conditions Prior to Occurrence Power: Reactor 1844 M9t.

Generator 645 M4e 4

Flow: Recirculation 15.6 x 10 6 Feedwater 7.06 x 10 lb/hr Description of Occurrence Cn Thursday, p l 3, 1981, during a surveillance test, the "A" isolation condensers' isolation valve V-14-30 failed to properly operate fully in the closed direction until the fourth stroke attenpt. On N W 2 4, V-14-30 was again stroked and failed to fully close. 'Ihe "A" isolation condenser was declared inoperable and the "B" isolation condensers' isolation valves were successfully operated in accordance with the plant's technical sI=W4caticos.

The limitorque operator for valve V-14-30 was in W , and the lower 1 1/2-threads of the sten nut were found to be AW. 'Ibe d=9ad threads were machined and on Sunday, 12/6/81, at approximately 1830, the "A" isolation cxxrlenser was determinea operable after a successful isolation valve operahility test.

Reportable Occurrence Page 2 Report No. 50-219/81-65/0lP On Der 7, in a subsequent action to determine the possibility of a generic actuator probim, the "B" isolation condenser was renoved fran service to repair leaking packing on valve V-14-32. Its st m nut was inspected and found to have three damaged lower threads and also showed indications of r.vlial cracking, approximately two inches in length up the stem nut.

-*OU In a further effort to investigate a possible generic . actuator proble, a reactor shutdown was cmmenced on Wednesday, Decmber 9, at approximately 1809, in order to cmplete further limitorque operator inspections.

Apparent Cause of Occurrence Presently under investigation.

Analysis of Occurrence We purpose of the isolation condensors arc to depressurize the reactor and to renove reactor decay heat in the event that the main condenser is unavailable as a heat sink. The isolation condensers inlet and outlets are equipped with dcuble isolation valves (A.C. and D.C.) that will automatically close on high steam or high condensare flow which is indicative of a pipe break. Failure of these valves to close result in degradation of the reactor coolant pressure boundary.

The safety significance of this event should be considered minimal since the redundant D.C. isolation valvo did close and the alternate isolation condenser was proved operable.

It is suspected that the sts nut failures may be a generic proble which r,ould result in failures of isolation valves in this systs and others importan*. to the reactor coolant pressure boundary and primary containment.

Corrective Action After V-14-30 failed to fully close, the valve operator was taken apart and inspected. Damaged threads in the lower part of the st a nut were repaired and the valve was placed back into service. In a subsequent effort to determine the possibility of a generic actuator probl e , the "B" isolation condenser was removed fr a service in order to inspect isolation valve V-14-32. Since the sts nut for V-14-32 showed indications of thread damage and cracking, the I

reactor was placed into the cold shutdown mode. Further corrective actions will l include inspection of other safety related isolation valve operators that are known to have been backseated and to open at least one suspect valve in order to inspect for possible internal valve damage.

Failure Data 10 inch Anchor Gate Valve Limitorque Operator Type SMB-2 P

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