ML20086E407

AO 74-17:on 741219,suppression Chamber Outboard Sample Valve Stuck in Open Position.Caused by Accumulation of Dirt Causing Binding of Solenoid Piston.Valve Cleaned

ML20086E407
Person / Time
Site:	Vermont Yankee
Issue date:	12/20/1974
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
AO-74-17, VYV-3484, NUDOCS 8312070092
Download: ML20086E407 (3)

Text

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A f.0O VEtoiONT YANKME N UCLEAR POWER COrwORNPION SCVCNTY SCVEN OROVC STRCCT Rt1TLAND, VEttMONT O~,701 ,

VYV-3484 "*

P. O. DOX 157 VCRNON VERMONT oS354 December 20, 1974 yCb /

Director .

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Directorate of Regulat8ry Operations, Region I j'hy /,s N United States Atomic Energy Commission .; , 8pOg 'Q Cl 631 Park Avenue  ;~

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King of Prussia, Pennsylvania 19406 -

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REFERENCE:

Operating License DPR-28 W/s  !

Docket No. 50-271 (; , i ' "

Abnormal Occurrence No. A0-74-17 (24 Hour Report) ' J.S

Dear Sir:

As defined by Technical Specifications for the Verr'ont Yankee Nuclear Power Station, Section 6.7, we are reporring the following Abnormal Occurrence as A0-74-17 and confirming our telephone conversation with your office.

At 1230 on December 19, 1974, the control room operator attempted to close the suppression chamber outboard sample valve (FS0-109-73a-2) and discovered that the control room panel indicating light did not.

indicate that the valve was closed. It was assumed at that tire that the valve in fact failed to close and as required by Technical Specifications 3.7.D.2, the inboard sample valve was placed in the closed position.

Instrument technicians examined the outboard valve, which is solenoid operated, and discovered that the valve was stuck in the open position. , Failure of this valve to close exceeds the Limiting Condition -

for Operations as stated in Technical Specifications 3.7.D.1, which requires that this valve be operable during power operation. The reactor was operating at 53% power ac the tine.

The valve was repaired and tested and the suppression chamber sample line was returned tc service at 1550 on December 19, 1974.

Very truly yours, 8312070092 741220 *

-[ M' ' 1h PDR ADOCK 05000271 S PDR &  ;

h Bradford W. Riley d Plant Superintendent .,

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COPY SENT REGION- H o

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, . .i O 6 Abnormal Occurrence Report -

i Report Number: 50-271/74-17 ^ \M91 k

Report Date: December 27, 1974 0 t./ gp y ay,  :,

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Occurrence Date: December 19, 1974 -

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Facility: Vermont Yankee, Vernon, Vermont t?.,+"., g s- .v Q Identification of Occurrence  ;,

Failure of Containment Air Sampling System valve to close.

Conditions Prior to Occurrence Steady state power operation at 53%.

Description of Occurrence At 1230 on December 19, 1974, the control room operator attempted to close the suppression chamber outboard sample valve (FS0-109-75A-2) .

and discovered that the control roce panel indicating light did not in-dicate that the valve was closed. It was assumed at that time that.the valve in fact failed to close and as requirec' by Technical Specifications 3.7.D.2, the inboard sample valve was placed in the closed position.

Following examination, the valve was verified to be stuck in the open posi- ,

tion. ,

Designation of Apparent Cause of Occurrence An inspection of the valve internals revealed an accumulation of dirt which caused binding of the solenoid piston. '

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Analysis of Occurrence FS0-109-75A-2 is required to provide primary containment isola- -

tion during the receipt of a Group Three (3) Isolation Signal. At the time of the failure the suppression chamber inboard sample valve (FS0-109-75A-1)

_ closed as required. Based on the containment isolation capability of the redundant sample valve, the failure of valve FS0-109-75A-2 did not present a less safe condition.

Corrective Action i

The valve was inspected, cicaned and satisfactorily tested.

Following this corrective maintenance, the suppression chamber sample line ,

was returned to service at 1550 on December 19, 1974. Based upon review of i their operating history, the Containment Air Sampling System valves will be cleaned and inspected once during each operating cycle in an attempt to prevent a reoccurrence of this incident.

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Abnormal Gecurrence Report Failure Data

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Solenoid Valve Piston - Part No. 15844 #68 Dr. (316 Stn. Stl.),

Atkonatic Valve Company. Previous failure data on FSO-109-75A-2 and related sample valves is as follows:

September 4, 1972 FS0-109-75A-1 and FS0-109-75A-2 Identical Identification. The details of this failure were reported in a Thirty Day Letter dated September 29,

• 1972.

November 1, 1972 FS0-109-75D-1 and FS0-109-76B Identical Identification. The details of this failure '

were reported in a Thirty Day Letter dated November 7, 1972.

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Bradford W. Riley Plant Superintendent w T

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