ML19291C282

AO 50-219/74/17:on 740307,during Transfer of Power from Auxiliary to Startup Transformer,Closing Switch for Breaker S1B Would Not Operate.Caused by Component Failure of Closing Spring Not Being in Charged Position

ML19291C282
Person / Time
Site:	Oyster Creek
Issue date:	03/15/1974
From:	JERSEY CENTRAL POWER & LIGHT CO.
To:
Shared Package
ML19291C260	List: ML19291C259 ML19291C264 ML19291C266 ML19291C270 ML19291C277 ML19291C282 ML19291C283
References
NUDOCS 8001230272
Download: ML19291C282 (3)

Text

NITACINENT VII Page 1 of 3 OiSTER C!H.I.k ::UCLt:AR GENLRAT1:M STAT 10l; F0htID RIVLR, ?E. JER$UY 0S731 Abnormal Occurrence Report lio. 50-219/74/17 Report Date March 15,1974

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Occurrence Date ,

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March 7,1974 -

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Identification of Occurrence Violation of the Technical Specifications, paragraph 3.7.B, when power operation of the reactor continued v;ith the SB transforner unavailabic for service for a tiec period greater than the Technical Specification licit of 7 days out of any 30 day period. This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15B.

Conditions Prior to Occurrence A routine plant shutdown was in progress.

The major plant parameters at the time of the event were as follows:

Power: Electric, 100 ?Tfe neactor, 2300 brit Flew: Recirculation, 7.5 x 104 gpm Feed' eater, 1.2 x 105 lb/hr Stack Gas: 210,000 uCi/sec Description of Occurrence m 2 220 On Thursday, March 7,1974, at 1700, as part of the routine plant shut-down procedure, it was required to transfer plant power from the 1B auxiliary trans former to the SB startup transfot=cr. The control room operator ca dety cperated the closing switch for the S1s breaker with no results. The reactor shutdown was terminated, holding the generator cicetric pcwr at appro.umately 100 Ne in order to maintain a power supply path through the IP, auxiliar,s- t rem s forme r. Inspection of the S1B breaker revealed that the closing spring was not in the charged position; hence, breaker closure was not possible in either the manual or automatic mode. The failure of the spring to wind has been traced to a failed spring can switch chien closes when the spring unwinds.* The can switch closure normally causas a relay, 52Y, to energi:a which in turn deenergices

• See attached repro-!ar:icn of pertir.cnt portion of Cencral Electric Drcuing No. 0223r.0173, Sheet 14

A'"'AClrCU' VII Page 2 of 3 Abnormal Occurrence No. 50-219/74/17 Page 2 the S1B breaker closing cell 52X. Cor. tacts frc= 52X in turn cause the spring winding motor to start and rewind the spring. Since the can switch centacts failed to cause.52Y to energi:c, a ccatinuous current was applied to 52X causing it to burn which resulted in frec:ing the ceil auxiliary contacts in their energited positica. It is thcught at this time that the failure of the spring to rewind occurred following the January 12, 1974 reactor shutdcwn cperation, since this was the last successful operation of the breaker. After replacing' the 52X coil and .

the failed can switch, successful transfer oC lead frof;.,1B auxillary transfer cr to the SB startup transfprcer'Ud:7achi*c~ved. '- t

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Apparent Cause of Occurrence

- t Component failure was the cause of this occurrence. The failure of the cam switch is presently under investigation. ,

Analysis of Occurrence The SIB breaker is ir. tended to close automatically when the IB auxiliary transforcer breaker trips. Had the breaker been required to ocrform this function, it would have resulted in a loss of power to the IL and ID 4100 volt switchgear. The 1-2 cmcrgency diesel generator would have initiated in the fast start mode and assuued Icad on the ID emergency b us .

Corrective Action At this time, it is thought that this occurrence is an isoleted incident.

However, all 4160 volt safeguard and 460 volt safeguard switchgcar will be checked to see that the closing springs have been properly charged.

In addition, the feasibility of installing a clesing circuit monitoring systc= will be explored with the Generation Engineering Departncnt.

Failure Da_ta Manufacturer data pertinent to the failed switch are as follows:

General Electric Company switch Part No. 456-AS568-5 4160V Switdigear 1792 221

ATI"ACIDE.'I' VII age o.

ICSPONSE 'IO DJCIGL?l: CUESTIO";S RENRTABLE OCCURanCE 50-219/74-17 section A of Enclosure Cuestions is pertinent since this event involved only one Startup power source.

BESP0;;SE:

A.1 Two circuits are no mally available; one was lost.

A.2 The cause of the event was the failure of a cam switch on th^ Startup transformer circuit breaker which prevented autantic closure of the breaker.

A.3 Only one switch in one system failed to function.

A.4 !b voltage excursion is pertinent to this event.

A.5 No frequency excursion is pertinent to this event.

A.6 The time out of service was not recorded in the BO. Since an electrician was required to correct the failed switch, it is estimated that the duration of this event was approx. one to two hours. Since the last successful operation occurred on 1/12/74, the switch was assuned and reported to be in this condition for a period of approx. 54 days.

A.7 Date of event: 3/7/74 1792 222