ML19319E574

RO 50-313/77-13:on 770602,reactor Bldg Cooling Fan VSFM-1A Found Inoperable.Caused by Motor Failure Due to Insufficient Lubrication of Motor Bearings.Vendor Will Repair Motor. Bearings Will Be Lubricated on Frequent Schedule

ML19319E574
Person / Time
Site:	Arkansas Nuclear
Issue date:	07/01/1977
From:	Mardis D ARKANSAS POWER & LIGHT CO.
To:
Shared Package
ML19319E569	List: ML19319E568 ML19319E574
References
NUDOCS 8004110827
Download: ML19319E574 (4)

Text

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L- Reportable Occurrence P.cport No. '

50--313/77-13

2. Report Date: July 1, 1977 3. Occurrence Date: June 2, 1977 4 Facility: Arkansas Nuclear One-llnit 1 Russellville, Arkansas 72801

5. Identification of Occurrence:

The failure of a Reactor Building cooling fan which is a condition leading to operation in a degraded mode pemitted by a limiting condition for operation (Technical Specification 3.3.4). .

6. Conditions Prior to Occurrence:

, Steady-State Power y Reactor Power 2568 MWth Hot Standby Net Output 805 MWe Cold Shutdown Percent of Full Power 100 %

Refueling Shutdown load Changes During Routine D Power Operation Routine Startup _

Operation Routine Shutdown ~

Operation Other (specify)

7. Description of Occurrence: -

At 2159 hours0.025 days <br />0.6 hours <br />0.00357 weeks <br />8.214995e-4 months <br /> on June 2,1977, Feeder Breaker B5-512 opened to Load Center B5, which supplies power to Reactor Building Cooling Fans VSFM- 1A 618. An investigation and meggering of both fan motors indicated grounded phase windings in VSFM-1A after which Load Center B5 was re-energized. The tripping of Breaker B5-512 indicated that selective tripping did not occur since .

Breaker 52-523 (feeder breaker to VSFM-1A) should have tripped.

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C\ Reportabic Occurrence Report No. 50-313/77-13

8. Designation of Apparent Cause of Occurrence:

Design Proc'e dure Manufacture Unusual Service Condition Including Environmental Installation /

Construction Component Failure X (See Failure Data)

Operator

. Cther (specify) X The motor bearings had insufficient lubrication.

9. Analysis of Occurrence:

Since a safety analysis was performed for operation with less than 4 RB cooling fans and the subsequently approved technical specification changes allow 2- cooling units to be operable and powered from independent busses, there was no hazard to the health and safety of the public.

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V Reportable Occurrence Report No. 50-313/77-13

10. Corrective Action:

The motor was removed and shipped to the vendor. (Reliance Electric

-Company) to be rebuilt. The remaining 3 fan unit's bearings were lubricated and will be placed on a more frequent lubrication schedule.

. The bearings in at least one of the redundant fans will be inspected by the end of the next refueling outage. A breaker test was performed on Breaker 52-523 which indicated that the trip had drifted high. A Preventive Maintenance Program is being established to test all vital 480 volt circuit breakers and calibrate all overcurrent relays.

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11. Failure Data:

Fan Motor: VSFM-1A, 480 volt, 125 HP, 1800 RPM, 60 cycle, 3 phase induction motor, fram design 7DB-5003, Reliance Electric Company.

Circuit Breaker: 52-523, 480 volt, 225 AMP ACB, Trip Coil Model OD-5, ITE Manufacturer.

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