ML20039G094

Forwards LER 81-065/01T-0.Detailed Event Analysis Encl

ML20039G094
Person / Time
Site:	Oyster Creek
Issue date:	12/23/1981
From:	Carroll J JERSEY CENTRAL POWER & LIGHT CO.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20039G095	List: ML20039G094 ML20039G098
References
NUDOCS 8201150279
Download: ML20039G094 (4)

Text

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i OYSTER CREEK > NUCLEAR GENERATING STATION o

emwe c ..J,

~. ,].v .ad% (609)693-6000 P O BOX 388

• FORKED RIVER

• NEW JERSEY

• 08731 Der 23, 1981

?

Mr. Ronald Haynes, Directer RECEIVED Office of Inspection and Enforcanent f '

Region I C JAN I 31982>' 4- '

United States Nuclear Regulatory Ommission a mim rwIDTcuculs 631 Park Avenue 9 " kW " 7 King of Prussia, Pennsylvania 19406

Dear Mr. Haynes:

4 .MW r0

SUBJECT:

Oyster Creek Nuclear Generating Station Docket No. 50-219 Licensee Event Report Reportable Occurrence No. 50-219/81-65/0lT This letter forwards three copies of a Licensee Event Report to report Peportable Occurrence No. 50-219/81-65/0lT in empliance with paragraphs 6.9.2. ,a,9 and 6.9.2. ,b,2 of the 'Ibchnical Specifications.

Very truly yours,

/ 4W

. T. Carroll, Jr Acting Director ter Creek JTC:dh Enclosures '

cc: Director (40 copies)

Office of Inspmtion and Enforcement United States Nuclear Regulatory Q2mtission Washington, D.C. 20555 Director (3)

Office of Managanent Information and Program Control United States Nuclear Regulatory Ommission Washington, D. C. 20555 8201150279 811223 NRC Resident Inspector (1)

. PDR ADOCK 05000219 S PDR Oyster Creek Nuclear Generating Station Forked River, N. J. d f Si $

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,I l OYSTER CREEK NUCLEAR GENERATING STATICN Ebrked River, New Jersey 08731 Licenseo Event Tuport Reportable Occurrence No. 50-219/81-65-OlT Report Date December 23, 1981 Occurrence Date I Decenber 9,1981 I Identification of Occurrence Limitorque operators and isolation valves for the Isolation Conde.aser Systen were found to have defects whidi did affect the operability of one valve and could affect those m other systems which perform a reactor coolant pressure boundary and prinary containment isolation function.

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

Additionally, valve V-14-30 in the Isolation Condenser Systen was found to be

inoperable, and failed to fully close when subjected to a close signal. This is determined to be operation in a degraded mode permitted 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 Mit

!. Generator 645 W e 4

Flow: Eecirculation 15.6 x 106 99" Feedwater 7.06 x 10 lb/hr f Description of Occurrence On Thursday, Decater 3,1981, during a surveillance test, the "A" isolation condensers' isolation valve V-14-30 failed to properly cperate fully in the closed direction until the third stroke attetpt. The valve was successfully cycled two more times and at the time it was suspected there was a problem with the torque switches. A rcaintenance job order was issued to inspect the switches.

On December 4, after discussions with the NBC Recident Inspector, who questioned the operability / reliability of V-14-30 (based on previous night's testing), a decision was made to stroke the valve to daronstrate operability.

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Ecportable Occurrence Page 2 Report No. 50-219/81-65/0lT On Decmber 4, V-14-30 was again stroked and failed to fully close. 'Ihe "A" isolation condenser was declared inoperable and the "B" isolation mndensers' isolation valves were successfully operated in accordance with the plant's technical specification requirments. 'Ihe limitorque operator for valve V-14-30 was inspected, and the lower 11/2 threads of the stm nut were fourx1 to be damaged. The damaged threads were machined and on Sunday, Decmber 6,1981, at approximately 1830, the "A" isolation condenrer was detennined operable after a successful isolation valve operability test.

On Decmber 7, in a subsequent action to determine the possibility of a generic actuator problem, the "B" isolation condenser, which was in need of packing repair on Valve V-14-32, was restoved frmt service. The stm nut on V-14-32 was inspected and found to have three damaged lower threads and also showed indica-tions of radial cracking, approximately two inches in length up the stm nut.

In a further effort to investigate a possible generic problm, a reactor shutdown was cntmenced on Wednesday, December 9, at approximately 1809, in order to cmplete further limitorque operator inspections. As a result of internal inspections of valve V-14-32, crack indications have been discoverd on the stm in the area of the stem backseat.

Apparent cause of Oc.mrrence It has been determined that the multiple nu:tber of backseating operations performed over the life of the plant in addition to the stresses induced by the thermal cycling of the valves while in the backseated position caused valve damage. After disassmbly of valve V-14-32 (steam inlet to the "B' isolation

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condenser) it was determined the stm backseat had been severely damaged enabling the st m to travel a distance further than designed. This resulted in damage to the limitorque operator stem nut by engagem2nt of the unthreaded portion of the valve st m into the st m nut.

, During the backseating process the limit switch and torque switch are bypassed l

to allow the full motor torque to be used to backseat the valve. This operation is performed at the circuit breaker by electrical personnel while fronitoring the motor amperage for protection of the motor. When a sudden rise in amperage is observed the notor is deenergized and the valve is left in this position until the next required valve operability test.

l i Analysis of Occurrence l 'Ihe purpose of the isolation condensers are to depressurize the reactor and ta

reove reactor decay heat in the event that the main condenser is unavailable as a heat sink. The isolation condensers' inlets and outlets are equipped with l

double isolation valves (A.C. and D.C.) that will automatically close on high l

steam or high condensate flow which is indicative of a pipe break. Failure of l

these valves to close would result in degradation of the reactor coolant pressure boundarf.

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Reportable Orarrence Page 3 Report No. 50-219/81-65/0lT The identified failures have the potential of preventing a safety systm frm cperating, causing a degradation in those systms providcxl to contain fission products, and/or creatiny a situation lmehng to high primary coolant systm leakage Corrective Action After V-14-30 failed to fully close, the valve operator was taken apart and inspected. Dannged threads in the lower part of the stan nut were repaired and the valve was pla d back into service. In a subsequent effort to determLne the possibility of a generic actuator problan, the "B" isolaticn condenser was raroved fran service in order to inspect isolation valve V-14-32. Since the atm. nut for V-14-32 showcx1 indications of thread damage and cracking, the reactor was shutdown and cooled down to less than 212 F.

The suspect isolation valve operators are being inspected for evidence of stan nut danuge. Furthermore, valve inspections are being perfonned on valves wirse sten nut exhibits the characteristics of valve stan over-extension. 'Ihe results of continuinJ inspection and further corrective action will be described in a supplanental report.

Station operating procedures will be reviewed and rnodified such that safety systan isolation valves will be backseated in an approved manner.

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

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