ML19347C803

Ao:On 731218-20,test Spool Valve for MSIV NS04A Failed to Properly Reset & Experienced Pressure Transients During & After 5% Closure Test.Caused by Faulty Operation of Test Valve & Improper Valve Resetting

ML19347C803
Person / Time
Site:	Oyster Creek
Issue date:	01/07/1974
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8103040600
Download: ML19347C803 (2)

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ersey Central Power & Light Company ! @If b

MADISON AVENUE AT PUNCH BOWL ROAD

• MORRISTOWN, N.J. 07960

• 201-533-6111 l

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General { , Public Utahties Corporation mu, January 7, 1974

s Mr. A. Giambusso g ' O '.-

Deputy Director for Reactor Projects y S ,. ~ ,M O j\\

Directorate of Licensing -

If m United States Atomic Energy Commission p  :,, ~J --

Washington, D. C. 20545 ,Q y

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Dear Mr. Giambusso:

$ i y,

Subject:

Cyster Creek Station Docket No. 50-219 Reset Problem with Test Spool Valve for Main Steam Isolation Valve NSO4A This letter serves to report the failure of the test spool valve for NSO4A to properly reset after a 5% closure test. The faulty operation of the test valve resulted in a condition which may have caused the main steam isolation valve (MS1V) to close slower than normal should an isolation signal a have occurred during the test interval. This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15D.

Notification of this event, as required by the Technical Specifications, paragraph 6.6.2.a, was made to AEC Region I, Directorate of Regulatory Oper-ations by telephone and telecopier on Thursday, December 20, 1973.

During the daily 5% closure exercises conducted on MSIV NS04A on December 18 and 19, pressure transients of 6 psig and 10 psig, respectively, were observed due to apparent valve overtravel. An analysis of the problem indicated that possibly the overtravel was caused by the test spool valve not

- resetting properly. On December 19, the reactor power was reduced to 853 MWt

(<401, of rated power) to facilitate further examination of the test spool valve assembly. A 5% valve closure test was performed with an instrument technician observing the valve. The sticking condition had apparently worsened, allowing the MSIV to go approximately 50*. closed before reopening in a normal manner.

During the test interval (approximately 2-3 minutes), if a situation existed whereby had MSIV NS04A received a signa to isolate, it is unlikely that the valve would have met the required closure time of <10 seconds since

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the exhaust air from the underside of the valve operator pis' ton must pass l through the test valve assembly. Because of the malpositioned valve assembly, i

l the exhaust air from the operator would have been restricted, thereby increasing W/03040 Goo __

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Ix s jMr. Giambusso January 7, 1974 the valve closure time. The consequences of this event are minimized since NSO4A would eventually close and the redundant valve, NS03A, would have provided isolation and closed in the required time, in the event of a reactor isolation. Furthermore, the " slow closure condition" was only present for the length of time the 5% closure test was in progress (2-3 minutes).

The test spool valve assembly for NSO4A was replaced. A 5% closure test and also a full closure timing test (6.7 seconds) were satisfactorily completed.

Upon removal and disassembly of the test spool valve, foreign material resembling red powder was found on and between the spool and sleeve assembly.

It has not bee n conclusively determined that this material was the cause of the valve sticking. The spool assembly is being sent to a testing lab for further examination.

Until the laboratory analysis on the defective test spool assembly is completed and a cause for the valve sticking is conclusively determined, the operation of the test valves on all four MSIVs will be closely observed for further evidence of this problem.

It is recognized that sticking is not a new problem with the 4-way air-and-spring operated valves (Numatics) used in the control circuits of the MSIVs at Oyster Creek, and work is in progress to formulate a modification to provide final resolution of this situation. The General Electric Company has recommended a modification to the MSIVs in which the present "Numatic" valves would be replaced with " Automatic" valves and manifold assemblies. This modi-fication is currently being reviewed by appropriate groups within Jersey Central --

Power G Light Company's Generating Department and, if adopted, an attempt will be made to have the installation work completed during the next refueling out-age presently scheduled for April 1974.

Enclosed are forty copies of this report.

Very truly yours,

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• Donald A. Ross .

Manager, Nuc1 car Generating Stations es .

cc: Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, kegion I

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