ML19282B674

LER 79-001/03L-0 on 790211:high Dew Point & Air Leakage on Breaker 2-6 Noted.To Preclude Breaker Damage,Breaker 2-6 Was Opened.Caused by Apparent Gasket Leak in Westinghouse C-A Breaker.Feeder & Breaker Repaired

ML19282B674
Person / Time
Site:	Indian Point
Issue date:	03/12/1979
From:	Gumble F POWER AUTHORITY OF THE STATE OF NEW YORK (NEW YORK
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19282B669	List: ML19282B668 ML19282B674
References
LER-79-001-03L-01, LER-79-1-3L-1, NUDOCS 7903160103
Download: ML19282B674 (2)

Text

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• 60 61 DOCKET NUVSER EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h lo l2l l While operating at 100 percent power, a high dew point and air leakage I o 3 l on breaker 2-6 associated with feeder 95331 was noticed by the System o 4 l Operator. In order to preclude possible breaker damage, breaker 2-6 l was opened with its load removed. In order to accomplish this, both [

[5TE"] l 138KV feeders 95331 and 95332 breakers to IP-3 were opened, thus l ,

]o l6 l l F0T7'l 6 I depriving e.9xv buses 5 and e from being energized by the 13axv I o g l feeders, as required by Technical Specification 3.7.A.2. 80 l

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47 CAUSE DESCRIPTION AND CORAECTIVE ACTIONS gl While feeders were de-energized, diesel generators assumed the l

, , 480V load requirements in accordance with Technical Fpecification I g

3.7.B.2. A subsequent investigation indicated gasket leak in l

, , l Westinghouse type C-A breaker. Repairs were effected, and both l l

feeder and breaker were returned to service. l 80 7 8 9

% POWER OTHER STATUS dis O Y DISCOVERY DESCRIPTION STA U Operator Observation l i 5 W h l1l0lOl@l NA l l Al@l A TivtTY CO TENT AMOUNT OF ACTIVITY LOCATION OF RELEASE RELE ASED OF RELE ASE nA l l Na l 7

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ATTACHMENT I

' Docket No. 50-286 Power Authority of the LER 79-001/03L-0 State of New York The plant was operating at 100 percent power.

On February 11, 1979, at 0120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> the System Operator rotified the Control Room Operator of a high dew point and air leakage signal on breaker 2-6 associated with feeder 95331. This feeder is a source of supply for the auxiliary 138KV feed to 6.9KV buses 5 and 6. It was necessary to remove the breakers from service to correct the problem and prevent breaker damage. However, opening the affected breaker while supplying load is not advisable with the indicated condition since it could be damaged. It was, therefore, necessary to remove all loads for 138KV feeder 95331 prior to opening breaker 2-6.

All three diesel generators were run to verify operability, in accordance with the requirements of Technical Specification 3.7.B.2, and generators Nos. 32 and 33 assumed the 480V load requirements for buses 5 and 6, which were previously being fed from outside power.

Breakers ST-5 and ST-6 (normal feed to bus 5 and 6, respectively) were opened and GT-35 and GT-36 were closed to provide power to the 6.9KV buses through the gas turbine sub-station transformer. The District Operator opened breaker 5-6, thereby removing load from 95331 138KV feeder. t;ith load removed, breaker 2-6 was then opened. At 0154 hours0.00178 days <br />0.0428 hours <br />2.546296e-4 weeks <br />5.8597e-5 months <br />, breaker 5-6 was reclosed, and GT-35 and GT-36 opened. ST-5 and ST-6 were reclosed and 480V buses were transferred back to their normal feed. All three generators were then secured and returned to their standby mode. Outside 138KV power to the 6.9 KV buses was thereafter supplied from feeder 95332 which meets the requirements of Technical Specification 3.7. A.2. Neither feeder 95331 nor 9533'2 had been supplying 6.9KV buses for a period of 34 minutes. However, this is well within the 48-hour limit allowed by Technical Specifications.

An investigation showed that fault lay in the manway for breaker 2-6, where a gasket leak was found. The Westinghouse CA-type breaker was subsequently repaired, and breaker 2-6 and feeder 95331 were returned tc service.

Reactor performance was not affected L" this incident. No similar events have been recorded to date.

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