05000265/LER-1979-004-03, /03L-0 on 790211:suction Isolation Valve Mo 2-1001-50 Failed to Close from Control Room.Caused by Failed Circuit Breaker in Valve Motor Control Center. Valve Taken Out of Svc for Repair During Outages

/03L-0 on 790211:suction Isolation Valve Mo 2-1001-50 Failed to Close from Control Room.Caused by Failed Circuit Breaker in Valve Motor Control Center. Valve Taken Out of Svc for Repair During Outages

ML19276F346
Person / Time
Site:	Quad Cities
Issue date:	03/06/1979
From:	Tietz G COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19276F341	List: 05000265/LER-1979-004, Forwards LER 79-004/03L-0 05000265/LER-1979-004-03, /03L-0 on 790211:suction Isolation Valve Mo 2-1001-50 Failed to Close from Control Room.Caused by Failed Circuit Breaker in Valve Motor Control Center. Valve Taken Out of Svc for Repair During Outages
References
LER-79-004-03L-03, LER-79-4-3L-3, NUDOCS 7903290035
Download: ML19276F346 (2)

LER-1979-004, /03L-0 on 790211:suction Isolation Valve Mo 2-1001-50 Failed to Close from Control Room.Caused by Failed Circuit Breaker in Valve Motor Control Center. Valve Taken Out of Svc for Repair During Outages

Event date:
Report date:
2651979004R03 - NRC Website

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valve MO 2-1001-50 failed to clo_se from the control room.

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the valve's motor control center.

The MO 2-1001-50 valve was electrically taken l

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LEL NUMBER:

LER/R0 79-04/03L-0 11.

LICENSEE NAME: Commonwealth Edison Company Quad-Cities Nuclear Power Station Ill.

FACILITY NAME: Unit Two IV.

DOCKET NUMBER: 050-265 V.

EVENT DESCRIPTION

On February 11, 1979, Unit Two was i ; the REFUEL mode and the shutdown cooling mode of RHRS was operating.

At 10: 30 a.m.,

the control room operator was taking shutdown cooling off when he discovered that the suction valve, M0 2-1001-50, would not close from the control room. Upon notifying the Shift Engineer, it was decided to take the valve out-of-service by tripping the breaker and thus closing the valve.

The second isolation valve, M0 2-1001-47 was also closed.

There has been no previous occurrences of this nature irvolving the M0 2-1001-50 valve.

VI.

PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The safety implications of this occurrence are minimal due to the fact the second Isolation valve, M0 2-1001-47, in the shutdown cooling suctic, line was fully operable at all times.

Therefore, had a Group 11 isolation signal occurred the 47 valve would have isolated the line.

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CAUSE

The initial investigation indicated that equipment failure was the probable cause of this occurrence.

A contact in the valve breaker was not operating properly.

During a future maintenance outage, a full investigation of the problem and the necessary repairs will be completed.

Vill.

CORRECTIVE ACTION

The immediate corrective action was to take the valve out-of-service electrically, closing it.

During a maintenance outage, when the valve can be appropriately operateJ and tested, the necessary repairs will be completed.

Until that t ime, p ri ma ry containment isolation is assured by the closure of M0-2-1001-50, and the operabili ty of valve M0-2-1001-47