ML18353B262

07/08/1975 Letter Submitting Abnormal Occurrence Report No. 75-14 Which Covers Failure of Bus 1D to Transfer from Station Power to Start-up Power

ML18353B262
Person / Time
Site:	Palisades
Issue date:	07/08/1975
From:	Sewell R Consumers Power Co
To:	Office of Nuclear Reactor Regulation
References
LER 1975-014-00
Download: ML18353B262 (3)

Text

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• consumers Power company General Offices: 212 West Michigan Avenue, Jackson, Michigan 49201

• Area Code 517 788-0550 July 8, 1975 Division of Licensing US Nuclear Regulatory Commission Washington, DC 20555 DOCKET _50-255, LICENSE DPR-20, PALISADES PLANT, A0-75-14 Abnormal Occurence Report No 75-14 covers the failure of Bus lD to transfer from station power to start-up power

• CC: JGKeppler, USNRC

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• 1 ABNORMAL OCCURRENCE REPORT Palisades Plant ,. . L Report Number: A0-75-14 2a. Report Date: July 8, 1975 2b. Occurrence Date: June 30, 1975 3. Facility:

Palisades Plant, Covert, Michigan 4. Identification of Occurrence:

Failure of Bus lD to transfer from station power to start-up power. 5. Conditions Prior to Occurrence:

Reactor made critical at 0503 on 6-30-75; turbine synchronized at 0930. Plant power was increased to 22!1/o. Then a feed-water pillrrp turbine driver trip resulted in a plant trip at 1333. 6. Description of Occurrence:

Following the plant trip, an annunciated alarm indicated Bus lD was not energized.

The 2400 V start-up 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 incoming 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 ment (ie, open when diesel generator breaker was open). 8. Analysis of Occurrence:

Bus lD power was available from either the 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 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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• 2 0 * .. 10. Failure Data: a. A survey of past maintenance orders indicates breaker (152-213)'

failed to close during a diesel generator test loading in May 1973. sequent investigation indicated failure was a synchrocheck circuitry.

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 investigator that further maintenance on the auxillary switch crank arm was not necessary.

The above maintenance and evaluation was performed on MO EPS-73-07 and Unusual Incident 73-24. Subsequent to the above maintenance, all 2400 V bus breakers were cleaned and inspected under MO SPS-74-o6, which was co:rr:q>leted on 9-26-74. No deficiencies were noted during this inspection.

b. Equipment Identification:

Allis-Chalmers Power Circuit Breaker, Model MA 250B, 4,760 Volts Max 1200 A:rr:q>s Continuous

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