ML19322E600

LER 80-014/01T-0:on 800302,emergency Diesel Generator 1 Failed to Synchronize & Tripped When Generator 2 Was Tagged for Mod.Caused by Component Failure.Fuse F7,found Loose in Holder.Fuseholder Repaired

ML19322E600
Person / Time
Site:	Oyster Creek
Issue date:	03/24/1980
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19322E598	List: ML19322E597 ML19322E600
References
LER-80-014-01T, LER-80-14-1T, NUDOCS 8004010485
Download: ML19322E600 (3)

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( EVENT DES,CRIPTION AND PROBABLE CONSEQUENCES h

> l:l~ l On March 2, 1980 during a Diesel Generator 20% Plus Load Test. emereenev i MT] l diesel generator #1 failed to syncronize and tripped at a time when 1

>64l l diesel generator #2 was tagged out of service for modification work. l 3 is j ; Both diesels were out of service in violation of T.S. 3.7.C.3 Diesel Il y, i generator No. 2 was restored to service in 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. On March 8, 1980 test- i 3;; l ing revealed that the malfunction of diesel generator #1 was caused by a j g,,, j loose fuse which would have affated operation in any mode. j y e EC t v!T E'? CAU!E cAUSE COVP. ValV F 0002 COLE SUB000E CO*.'FO*;E':7 00DE SL'E 0CE CUE 000E

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42 4 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h 110l l The cause of this occurrence is attributed to component fgilure. Fuse, 1 gl F7, was found loose in its holder. The fuseholder was repaired. The l g; fuse holder for diesel generator #2 will be inspected when it is taken  ;

out of service. The procedure for the annual inspection of the diesel l l

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" ff Q Madison Avenue at Punch Bow! Road Morristown, New Jemey 07960 l (201)455-8200 OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/80-14/lT s

Report Date March 24, 1980 Occurrence Date  !

March 2, 1980 Identification of Occurrence Vio.lation of the Technical Specifications, paragraph 3.7.C.3, when both standby diesel generators were out of service for almost five hours.

This event is considered to be a reportable occurrence as defined in the Tech-nical Specifications, paragraph 6.9.2.a.2.

This was recognized as a reportable occurrence at 10:30 a.m. on March 8, 1980, following identification of cause.

Conditions Prior to Occurrence -

The plant was shutdown for a refueling / maintenance outage.

The reactor was subcritical.

The reactor mode switch was locked in refuel.

The cavity was flooded.

Description of Occurrence On Sunday, March 2, 1980, at 9:26 a.m., during surveillance test (636.4.003)

Diesel Generator 20% Plus Load Test, emergency diesel generator #1 failed to syncronize and tripped. Concurrently, emergency diesel generator #2 was tagged out of service fo- modification work; both diesel generators were inoperable.

At 10:41 a.m., the reactor mode switch was locked in shutdown position. An administrative hold on moving fuel and any work which could cause a reduction of reactor cavity water level was put into effect when both diesels were inoperable.

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l Jerse, Centra' Power & Lgn: Company is a Memm c/ t .e Gene a Pub.:: U:ct es Sys:em

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R2portcble Occurrsnca Ns. 50-219/80-14/1T Peg 2 2 March 24, 1980 Emergency diesel generator #2 was racked in and tested in accordance with Diesel Generator 20% Plus Load Test. Diesel generator #2 was available for service at 2:21 p.m.

After the initial occurrence of this failure on March 2, 1980, extensive testing of #1 diesel generator was performed to determine the cause. The investigation included connection of test instrumentation to identify the failed component.

The problem, however, was intermittent and was not identified until March 8, 1980.

s During this period, it was not known whether the malfunction would affect the fast start capability (emergency mode).of the unit. Testing revealed that a loose fuse in the "A" phase potential transformer circuit to the voltage regula-tor was the cause of the malfunction. It was further determined that this mal-  ;

function would have affected operation of the unit in any mode, thus requiring )

-a licensee event report.

Apparent Cause of Cccurrence i

The cause of this occurrence is attributed to component failure. A fuse, F7, was found loose in its holder.

Analysis of Occurrence The emergency diesel generator system assures there is an adequate supply of standby power for operation of equipment required for a safe plant shutdown, to maintain the plant in a safe shutdown condition, and to operate the required engineered safety feature equipment following an accident. Since this condition  ;

occurred during refueling and maintenance, with the reactor shut down and less than 212*F, the safety significance is minimal. Additional administrative con- ,

trols which stopped fuel movement and limited maintenance work on reactor systems '

further reduced the probability of requiring safety systems to operate. For a refueling accident, the standby gas treatment system is required to operate.

For this specific incident, offsite power was available. Technical Specifications allow degraded emergency core cooling systems during refueling.

l Corrective Action The loose fuse holder on diesel generator #1 was repaired. Diesel generator #2 fuse holder will be inspected when it is taken out of service. The annual inspec-tion procedure of the diesel generators will be revised to incorporate the inspec-tion of fuse holders for tightness and security.

Failure Data Not appilcable, l

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