ML20085F910

AO 75-014:on 750630,bus 1D Failed to Transfer from Station Power to Startup Power.Caused by Failure of Incoming Breaker 152-202 to Close Automatically Due to Diesel Generator Breaker 152.213 Interlock.Synchrocheck Circuitry Repaired

ML20085F910
Person / Time
Site:	Palisades
Issue date:	07/08/1975
From:	Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Office of Nuclear Reactor Regulation
Shared Package
ML20085F909	List: ML20085F902 ML20085F910 ML20085F915
References
AO-75-014, AO-75-14, NUDOCS 8308230608
Download: ML20085F910 (3)

Text

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Washington, DC 20555 DOCKET 50-255, LICENSE DPR-20, PALIGADES PLANT, A0-75-14 Abnormal Occurence Report No 75-14 covers the failure of Bus 1D to transfer from station power to start-up power.

Ralph B. Gewell (Signed)

Ralph B. Sewell Nuclear Licensing Administrator CC: JGKeppler, USNRC l

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" ::33 8308230600 751210 DR ADOCK 05000255 PDR COPY SENT REGION, w

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!O ABNORMAL OCCURRENCE REPORT i Palisades Plant l I t

I 1. Report Number: A0-75-lh  !

! 2a. R_eport Date: July 8, 1975 2b. Occurrence Date: June 30, 1975

! Facility: Palisades Plant, Covert, Michigan 3

! 4. Identification of Occurrence: Failure of Bus ID to transfer from station power to start-up power.

l S. Conditions Prior to Occurrence: Reactor made critical at 0503 on i

6-30-75; turbine synchronized at 0930. Plant power was increased to  ;

j 22%. Then a feed-water pump turbine driver trip resulted in a plant trip at 1333

6. D_escription of Occurrence: Following the plant trip, an annunciated i alam indicated Bus 1D was not energized. The 2400 V start-up trans-former was available and diesel generator 1-2 was running. The control operator manually closed the start-up power incoming breaker (152-202) .

The bus was de-energized for less than 30 seconds.

7 Designation of Apparent Cause: The start-up power inccming breaker

, (152-202) failed to close automatically due to a diesel generator breaker

] (152-213) interlock (ie, if the diesel generator is on line and providing power to the bus, the start-up power breaker will not automatically close onto that bus). An auxillary (b-type) contact within the diesel generator breaker provides the interlock function. This contact was out of adjust-ment (ie, open when diesel generator breaker was open).

8. Analysis of Occurrence: Bus 1D power was available from either the start-up transformer or the diesel generator, but manual closing of the breaker was required. Thus, had the engineered safeguards equipment been required to function, it would have been delayed by the time required to identify the situation and close the breaker manually.

9 Corrective Action:

a. Conduct survey to determine if auxillary switch crank arm is properly

, engaged on all engineered safeguards breakers.

b. Verify proper auxillary switch rotor assembly adjustment on all 4

engineered safeguards breakers,

c. Force movable portion of circuit breakers to extreme right of breaker

, cubicle and verify proper engagement of auxillary switch crank arm.

Shim auxillary switch mounting bracket as required to achieve proper engagement.

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! 10. Failure Data: I i

n. A survey of past maintenance orders indicates breaker (152-213) failed to close during a diesel generator test loading in May 1973 Sub-sequent investigation indicated failure was a synchrocheck circuitry.

2 During this repair, it was noted the auxillary switch crank arm had been broken and brazed at an earlier date. It was concluded by the 4

investigator that further maintenance on the auxillary switch crank j arm was not necessary. The above maintenance and evaluation was performed on MO EPS-73-07 and Unusual Incident 73-24  ;

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i all 2400 V bus breakers were  ;

j Subsequent cleaned and inspected to the above maintenance,4-06, under M0 SPS-7 which was cosqpleted on l

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9-26-74. No deficienc3es were noted during this inspection.

b. Equipment Identification: Allis-Chalmers Power Circuit Breaker, Model MA 250B, 4,760 Volts Max 1200 Amps Continuous i

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