05000333/LER-1980-016-03, /03L-0:on 800125,during Normal Operation, Containment Isolation Valve 20-MOV-82 Was Inoperable.Caused by Ground Fault.Replaced Burned Up Motor Limit Switch Assembly,Torque Switch Assembly & Modified Termination Box

/03L-0:on 800125,during Normal Operation, Containment Isolation Valve 20-MOV-82 Was Inoperable.Caused by Ground Fault.Replaced Burned Up Motor Limit Switch Assembly,Torque Switch Assembly & Modified Termination Box

ML19296C833
Person / Time
Site:	FitzPatrick
Issue date:	02/22/1980
From:	W. Verne Childs POWER AUTHORITY OF THE STATE OF NEW YORK (NEW YORK
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19296C823	List: 05000333/LER-1980-016, Forwards LER 80-016/03L-0 05000333/LER-1980-016-03, /03L-0:on 800125,during Normal Operation, Containment Isolation Valve 20-MOV-82 Was Inoperable.Caused by Ground Fault.Replaced Burned Up Motor Limit Switch Assembly,Torque Switch Assembly & Modified Termination Box
References
LER-80-016-03L, LER-80-16-3L, NUDOCS 8002280623
Download: ML19296C833 (2)

LER-1980-016, /03L-0:on 800125,during Normal Operation, Containment Isolation Valve 20-MOV-82 Was Inoperable.Caused by Ground Fault.Replaced Burned Up Motor Limit Switch Assembly,Torque Switch Assembly & Modified Termination Box

Event date:
Report date:
3331980016R03 - NRC Website

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due to ground faults.

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PHONE a o o= so g' NAME OF PREPApER

POWER AUT!!ORITY OF Tile STATE OF NEF 7K JAMES A. FIT: PATRICK NUCLEAR POWER

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DOCKET NO. 50-333 ATTACIDENT TO LER 80-016/03L-0 Page 1 of 1 During normal operation, on January 25, 1980, Drywell Floor Drain Inside Isolation Valve (20-MOV-82) blew a control power fuse. The outside isolation valve (20-A0V-83) for the same containment penetration was placed in the closed position as required by Technical Specifications paragraph 3.7.D.1 while investi-gation into the blown fuse was conducted.

Investigation revealed a ground fault (inside the drywell) on portions of the control circuit associated with 20-MOV-82 which resulted in a short circuit

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'which in turn caused overloading of the control power fuse.

Lifting a ground connection (provided by design) at one side of the control power transformer 3

secondary winding (outside the drywell) eliminated the short circuit and restored the valve to operable status approximately four (4) hours later.

On January 31, 1980, an annunciator indicated loss of control power to 20-MOV-82.

Investigation revealed additional ground faulting of those portions of the control circuit inside of the drywell.

In addition, this ground faulting had apparently caused an open signal to the valve motor operator.

Since the valve was already in the open position, this open signal resulted in cicctrical. failure of the valve operator motor. The outside isolation valve (20-A0V-83) and manual valve RDW-77, just downstream of 20-MOV-83, were both placed in the closed position to satisfy Technical Specification requirements with respect to containment isolation.

Normal system Icakage inside of the drywell to the floor drain system requires periodic pump out of the floor drain sump.

In order to complete this pump down activity 20-A0V-83 and manual valve RDN-77 were opened for apptaxima.ely two minutes out of each hour. Operation in this manner continued until a plant shutdown was initiated on February 4,1980 to effect repairs.

Investigation into the cause of the control circuit ground faults inside the drywell revealed that the valve operator terminal box was physically oriented in such a manner as to permit the flooding due to condensation.

The flooding caused the ground faulting which resulted in destruction of the valve operator motor.

The motor and the associated torque and limit switch assemblies were replaced, the valve operator was reoriented 90 to prevent the co11cetion of condensation within the terminal box and the terminal box was mod-ified to provide a drain path for condensation.

In addition, an inspection of other motor operator valves inside primary containment was conducted to identify other components which might be subjected to the same type of failure.

This investigation revealed three (3) additional motor operators with similar orientation.

In each case, these other motor operators were reoriented to prevent collection of condensation within the terminal box and/or the terminal box was modified to provide a drain path. These actions should preclude recurrence. The event did not represent any significant hazard to the public health and safety.

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