ML20086E840

AO 73-34:on 731217,station Svc Water Pump a 4-kV Breaker Stationary Auxiliary Switch Assembly Rear Mounting Tie Bolt Found Disengaged.Bolt Tightened

ML20086E840
Person / Time
Site:	Vermont Yankee
Issue date:	12/19/1973
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086E839	List: ML20086E835 ML20086E840
References
AO-73-34, VYV-3102, NUDOCS 8312070535
Download: ML20086E840 (3)

Text

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- I VERMONT YANKEE NUCLEAR POWER CORPOR ATION h

SEVENTY SEVEN OROVE STRCCT

- RuTuxo, VERMONT 03701

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VYV-3102

[ P. O. BOX 15's

[ VERNON, VERMONT oS354

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I December 19, 1973 m i b

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. United States Atomic Energy Commission ._

Directorate of Regulatory Operations, Region I 631 Park Avenue

_ King of Prussia, Pennsylvania 19406 -

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REFERENCE:

Operating License DPR-28 I Docket No. 50-271 Abnormal Occurrence No. AO- 7 3- 34

• Gentlemen:

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As defined by Technical Specifications for the Vermont Yankee Nuclear -

Power Station, Section 6.7.B.1, we are reporting the following Abnormal y Omo i m me oo AC-73 ^A oum u v a f l u.J o e, v u m sclcyhunc evuveu,uciva with yvut

office.

! On December 17, 1973, while investigating a reported problem involving

$ the "A" Station Service ' dater Pump 4 KV breaker, cn electrician noted the y fact that the breaker stationary auxiliary switch assembly rear mounting y bolt had loosened and was disengaged from its mounting plate. This bolt E serves to assist in maintaining proper switch contact alignment. The

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[ loosening and subsequent backing out of the bolt caused some misalignment f g of the switch auxiliary contacts which would have rendered those contacts y inoperable had the breaker operated. This failure is not considered to be an abnormal occurrence, but is merely referenced to detail appropriate ..( -

background information.

t E As a result of this incident, an investigation of all 4 KV breakers . . . .

5 was initiated. This investigation, which was completed on December 19, 1973, i indicated that all 4 KV breakers exhibited varying degrees of bolt loosening.

Due to the fact that some breakers are associated with safety related systems, Y'%'

E it was determined that this condition was in violation of Technical E %.c

. Specifications, Section 1.A.4 in that it could have resulted in one or more %d' 6 engineering safety feature failures which could have caused or threaten to TP7.E cause that feature or component to be incapable of performing its intended 14 W%

h function as defined in the Technical Specifications. .

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VERMONT YANKEE NUCLEAR POWER CORPOMATIO.

Directorate of Regulatory Operations -

December 19, 1973 ;W : ;., ,;

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Tightening of all loose switch bolts was initiated immediately 3 . .q-i . ~.

upon discovery and completed by 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> on December 19, 1973.  :?

. d ,[.3 The reactor was operating at approximately 68% power at t.he time of . ;.,

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this incident.

Sincerely, fjf:[

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VERMONT YANKEE NUCLEAR POWER CORPORATION 's i.. i-:, . -

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B.W. Riley Y TIdd 57 Plant Superintendent -

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MEMO ROUTE SLIP Sac ** a bout th's- For coacurreaca- For actiaa-r,m uc-n inev. sin i4, e>4n .uoi o24o No.e.-d ,e,,,n ro, ,i,n.,o,s. x r., in,o,m.,i.

TO (Name and unit) intTIALS REMARKS RO Chief, FS&EB VERMONT YANKEE NUCLEAR P0lJER CORPORATION RO: LIQ (5)

RO Files oAn A0 73-34 Central Mail & Files Regulatory Standards (3)

TO (Name and unst) WTIALS REMAAK5 Directorate of The above abnormal occurrence is forwarded for Licensing (13)

OGC oAn information. Distribution will be made by this Regional Directors (II, III, IV) office to the PDR, Local PDR, NSIC, DTIE, and TO (Name and unit) W TLAL.S RidAAKS State Representatives after review by the oAn licensee for proprietary information.

FROM (N me and unst) REMAAK$

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8.h E J. Brunner Region I PHOhl MO. DATE 8-337-1246 1/9/74 USE OTHER SIDE FOR ADL4TIONaL REMARKS cpo:3,tg o.4454s, c.c .

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