ML19347C759

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AO 29-75:on 751206,through Wall Water Leak Seen in Threaded 1-inch Schedule 160 Pipe Nipple at Inlet to Pump Discharge Relief Valve on Sys 1.Possibly Caused by vibration-induced Fatigue.Nipple & Associated Flange Replaced
ML19347C759
Person / Time
Site: Big Rock Point File:Consumers Energy icon.png
Issue date: 12/16/1975
From:
CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
References
NUDOCS 8102130093
Download: ML19347C759 (1)


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ABNORMAL OCCURRENCE REPORT Big Rock Point Plant 1.

Report No: A0-29-75, Docket 50-155 2a.

Report Date: December 16, 1975 2b.

Occurrence Date: December 6, 1975, Classified as A0 on December 9, 1975 3

Facility: Big Rock Point Plant, Charlevoix, Michigan h.

Identification of Occurrence: Failure of piping component in control rod drive pump No 1 discharge piping.

5 Conditions During Occurrence: Plant shut down for minor repairs and rou-tine testing.

6.

Description of Occurrence: A through wall water leak was observed in a threaded 1" Schedule 160 pipe nipple at the inlet to the pump discharge relief valve on the No 1 system. The unit was immediately removed from service and the No 2 pump was immediately put in service. Maintenance was notified to investigate and repair.

7 Designation of Apparent Cause of Occurrence: Unknown. Probable cause is vibration induced fatigue. A metallurgical examination will be conducted.

8.

Analysis of Occurrence: The pump system provides drive cooling water, scram accumulator charging energy and normal drive maneuvering powe" and these functions were not lost due to this deficiency.

9 Corrective Action: The pipe nipple and associated flange were replaced and satisfactorily tested prior to plant start-up on December 7, 1975 10.

Failure Data: One-inch carbon steel Schedule 160 pipe nipple.

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