ML20090D833

AO-50-219/75-01:on 750108,during Surveillance Test,Vacuum Breaker V-26-16 Failed to Demonstrate Operability.Caused by Unstable Balance Condition at Valve Closure Point.Turn Buckle Adjusted

ML20090D833
Person / Time
Site:	Oyster Creek
Issue date:	01/17/1975
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	Giambusso A Office of Nuclear Reactor Regulation
References
AO-50-219-75-01, AO-50-219-75-1, NUDOCS 8303020464
Download: ML20090D833 (4)

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Jersey Central Power & Light Company j(,;

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MADISON AVENUE AT PUNCH BOWL ROAD

• MORRISTOWN, N.J. 07960

• 201-533-6111 anu a w rus ,

General '[f,*[, Public L,alities Corporation SYsta w bi January 17, 1975

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4' Mr. A. Giambusso 'L'/ d. . . 8 xb Deputy Director for Reactor Projects 7 - g 'S Directorate of Licensing United States Atomic Energy Commission Washington, D. C. 20545

Subject:

Oyster Creek Station Docket No. 50-219 Abnormal Occurrence Report No. 50-219/75-1 The purpose of this letter is to fonvard to you the attached Abnormal Occurrence Report in compliance with paragraph 6.6.2.a of the Technical Specifications.

Enclosed are forty copics of this submittal.

V truly yours,

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Donald A. Ross Manager, Generating Stations-Nuclear

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es Enclosures cc: Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Region 1 050 f0EAS0cfaM8fj;i, PDR k

O O Jersey Central Power & l:ight Company k'J MADISON AVENUE AT PUNCH BOWL ROAD

• MORRibIOWN, N. J. 07960

• 201-539-6111

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General jf,] Pubhc Utilities Corporation m r. .

P OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence f-Report No. 50-219/75-1 i

Report Date January 17, 1975 .

Occurrence Date January 8, 1975 -

Identification of Occurrence

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Failure of one reactor building to torus vacuum breaker valve to demonstrate-operability during quarterly surveillance testing. This event is considerdd-to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15D. <* -

Conditions Prior to Occurrence ~'

The plant was at cady state power with major parameters as follows: ' [

Power: Core 1916 MWt ~

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Electric, 674 MWe Recirculation, 15.5 x 104 gpm Flow:

Feedwater, 7.6 x 106 lb/hr Stack Gas: 27,575 pCi/sec 4 Description-of Occurrence

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On Wednesday, January 8, 1975, at approximately 1240, while performin'g quarterly surveillance testing on the two air-o:erated reactor building to torus vacuum breaker valves, it was found that vr _um breaker V-26-16 failed to demonstrate operabilitf. V-26-16 failed to ut.., cat as an increasing differential pressure was applied to_ differential pressure switch DPS66A. Testing was terminated when the maximum allowabic opening -differential pressure (0.5 psid) was reached.

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O O Abnormal Occurrence Report No. 50-2,19/75-1 Page 2 Apparent Cause of Occurrence.

This failure is attributed to an unstable balance condition at the valve closure point. The actuator positioner is a proportional device which relies on negative (position) feedback. With the valve at one extreme (i.e. , closed position), the positioner was adjusted to obtain a balanced condition. When the signal air pressure changed, calling for further closure, air pressure at the bottom of the actuator piston increased to a value of the supply pressure since negative feedback was not realized. The feedback did not occur because

, significant position change will not result at full closure. Therefore, l pressure continued to increase to 100 psi below the piston causing the valve

-disc to drive hard into seat.

s Analysis of Occurrence Since the reactor building to torus vacuum relief system is a redundant system and full capacity is available through either air operated valve (V-26-16 or V-26-18), the safety significance of this event is the loss of redundancy.

Corrective Action

.The following adjustment was made:

(1) Valve was switched to "close" position (2) Tension on turn buckle linkage was then relaxed and actuator piston permitted to bottom out against upper stop.

(3) Turn buckle was then adjusted to cause valve position pointer to just align with "close position" scribe while maintaining actuator shaft stationary, thus preventing overtravel.

Engineering efforts are currently underway in two areas:

(1) A modification of the valve actuator to increase the closing force.

-(2) Replacement of the entire valve assembly, including actuator, due to historical leakage prob 1 cms associated with these valves.

Failure Data Previous reactor building to torus vacuum breaker test failures are listed below:

November 23,1970 - V-26-18 failed to open during operability testing.

December 18, 1970 - V-26-16 and 18 failed to open during operability testing.

January 12, 1971 - V-26-18 failed Icakage test, p *%

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1 i Abnonnal Occurrence Report No'. 50-219/75-1 ~

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[ January 13, 1971 - After linkage adjustinent, V-26-18 passed leakage test, but j

. subsequently failed to open.  !

May 3, 1973 - V-26-18 failed Icakage test. ~

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1 April 9, 1974 - V-26-16 failed Icakage test. ,.

l May 28, 1974 - V-26-16 failed leakage test.

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