05000219/LER-1981-072, Forwards LER 81-072/03L-0.Detailed Event Analysis Encl

Forwards LER 81-072/03L-0.Detailed Event Analysis Encl

ML20040F513
Person / Time
Site:	Oyster Creek
Issue date:	01/28/1982
From:	Carroll J GENERAL PUBLIC UTILITIES CORP.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20040F514	List: 05000219/LER-1981-072, Forwards LER 81-072/03L-0.Detailed Event Analysis Encl 05000219/LER-1981-072-03, /03L-0:on 811229,core Spray Sys I Parallel Isolation Valve V-20-15 Became Inoperable in Partially Open Position.Caused by High Motor Current Drawn When Valve Close Signal Inadvertently Intiated During Valve Stroking
References
NUDOCS 8202090285
Download: ML20040F513 (3)

LER-1981-072, Forwards LER 81-072/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2191981072R00 - NRC Website

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GPU Nuclear Q

gf P.O. Box 388 Forked River, New Jersey 08731 609-693-6000 Wr;ter's Direct Dia! Number:

January 28, 1982 to I9 Mr. Ibnald C. Haynes, Adninstrator d

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Region I United States Nuclear Regulatory Conmission

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631 Park Avenue King of Prussia, Pennsylvania 19406

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Dear Mr. Haynes:

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SUBJECT: Oyster Creek Nuclear Generating Stati Docket No. 50-219 Licensee Event Report Reportable Occurrence No. 50-219/81-72/3L This letter forwards three copies of a Licensee Event Report to report Reportable Occurrence No. 50-219/81-72/3L in ccmpliance with paragraph 6.9.2.b.2 of the Technical Specifications.

Very truly yours, g

J. T. Carroll, Jr.

Acting Director Oyster Creek J'IC:dh Enclosures cc: Director (40 copies)

Office of Inspection and Enforcement United States Nuclear Regulatory Conmission Washington, D.C.

20555 Director (3)

Office of Management Information and Program Control United States Nuclear Regulatory Ca mission Washington, D. C. 20555 NRC Resident Inspector (1)

Oyster Creek Nuclear Generating Station ForkExl River, N. J.

8202090285 820128

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PDR ADOCK 05000219 S

PDR GPU Nuclear is a part of the General Pubhc Utilities System

OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/81-72/3L Report Date January 28, 1982 Occurrence Date Deceber 29, 1981 Identification of Occurrence The Oore Spray Systs I parallel isolation valve (V-20-15) hamma inoperable in a partially open positicn when its notor breaker tripped.

This event is considered to be a reportable occurrence as defined in the Technical Specifications, paragraph 6.9.2.b 2.

Conditions Prior to Occurrence The plant was in the refueling node with reactor coolant taperature less than 2120F Description of Occurrence On Deceber 29, 1981 during the routine surveillance of the Core Spray Systs I reactor low pressure sensors, the notor circuit breaker of parallel isolation valve V-20-15 tripped when the actuating pressure sensor was reset. Parallel valve V-20-40, which is actuated by the same pressure sensor, operated normally.

The circuit breaker for V-20-15 was not damaged and the notor and electrical syst s was intact. On Drmnhor 30, 1981 va3ve stroking currents were read with the breaker reset. The breaker tripping elments were also tested to de ominn e

their setpoints. All parameters were found to be normal. 'Ihe valve operability 1.

surveillance procedure was repeated, and the valve stroked without incident.

Apparent Cause of Occurrence The alparent cause of occurrence was the inadvertent initiation of a valve closure signal during the period when the~ valve was still' moving toward the open position. This occurs when the valve open signal is rm oved in less time than is required for the valve to assume the full open/stop position. The instant-aneous reversal in direction of the notor operator is not the intended node of operation. The reversal of notor inertia while driving open required greater than normal torque causing an increase in the current to be seen by the notor circuit breaker. The added current would have caused the circuit breaker to trip.

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Reportable Occurrence Page 2 Report No. 50-219/81-72/3L Analysis of Occurrence There are two motor operated isolation valves installed in parallel in each core spray loop outside the drywell. h e valves are normally closed and can be opened by switches in the control rom and by local keylock switches. Wey open automatically on a low reactor pressure of less than 285 psig.

Had the Core Spray System been required at the time the valve became inoperable, the system would have operated as intended. Each of the parallel isolation valves is designed for rated systs flow and the alternate parallel valve, V-20-40, would have functioned as designed. Werefore, the safety significance of this event is considered to be minimal.

Corrective Action

An informal test has been conducted by Plant Engineering to d m onstrate the changes in current magnitude during conditions similar to the events that occurred. We results of this test indicate that the starting current during an instantaneous reversal in notor direction is significantly higher (30-60%) than normal starting current and places the current in the range for a breaker trip.

An engineering investigation is undenray to further analyze this proble and those corrective actions that are found necessary as a result will be imple-mented.

Failure Data Not applicable.