ML20084J138

Ro:On 721223,reactor Water Cleanup Sys Outboard Isolation Valve Mo 2-1201-5 Failed to Close.Caused by Failure of Torque Switch.Switch Replaced

ML20084J138
Person / Time
Site:	Quad Cities
Issue date:	01/05/1973
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084J139	List: ML20084J138 ML20084J143 ML20084J149 ML20084J154
References
BBS-73-4, NUDOCS 8305120182
Download: ML20084J138 (2)

Text

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1. e 4#^ Com ~ wealth Edison Qua Nuclear Power Station .VA {Dd a

Post O Box 216 k, 3,d '

Cordova,Ilhnois 61242 y- Telephone 309/654-2241 e  ?

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January 5, 197 GM J/

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• NO Mr. Angelo Giambusso Deputy Director of Reactor Pro,Jects Directorate of Licensing U. 8. Atomic Energy Commission Washington, D. C. 20545

Reference:

Quad-Cities Nuclear Power Station - Unit 2 DPR-30, Appendix A, Docket No. 50-265 Sections 1.0.A.2, 3.7.D.1, and 3.7.D.2.

Dear Mr. Giambusso:

The purpose of this letter is to inform you of the details regarding an incident in which the Reactor Water Cleanup system outboard isolation valve, MO 2-1201-5, failed to close. This incident was reported to you by telegram on December 24, 1972.

DESCRIPTION OF THE INCIDENT At 6: 00 a.m. on December 23, 1972, Reactor Water cleanup recirculation pump 2A was taken out of service due to leakage at the pump seals. The system was isolated by closing valves 2-1201-2, 5, and 80. All valves operated satisfactorily.

The cleanup system was returned to service later that day with pump 2B in operation. At approximately 9: 00 p.m.,

2B cleanup pump developed seal leakage. Tne load on the unit was re-duced to 60% to maintain a low conductivity.

At 11:20 p.m. , the cleanup sys tem was removed from service' in order to work on the cleanup recirculation pump seals or both A and B pumps. At this time, MO-2-1201-5 did not close when actuated from the control room. Af ter giving the valve a "close" signal, a double indication was received and the 1 valve would not reach the fully closed position. Inboard isolation valve M3 2-1201-2 was clo's'ed to comply wivh Technical T Specifications.

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O Mr. Angelo Giambusso January 5,1973 Electrical maintenance personnel were called in to repair the valve operator on December 24, 1972. After repairs were completed later that day, the valve was operated three times from the control room. Each time the valve closed in 22 seconds. Cleanup recirculation pump 2A was returned to service' at 10: 30 p.m. and the cleanup system returned to normal. ,

INVESTIGATION AND ' CORRECTIVE ACTION The problem was identified as a failure of the tornue

_ switch _ to return to the "close" position af ter the last i valve operation. When maintenance. personnel checked out the torque switch, the internal torsion spring was found )

to be weak and unabic to reclose the switca af ter it had i actuated. The switch must reclose to set up .the valve ,

motor closing circuit. The switch is a type 00 Limitorque.

When it was replaced and reset, the valve operated success-fully.

Similar problems have been encountered in the past as reported in my letters dated July 10, August 3, September 3, and

~ De ce mbe r 6, 19 72. A review of the' status of all valve operators is being conducted by Commonwealth Edison's Station Electrical Engineering Department. This review - has not been -

completed as of this date; however, it program of . corrective action is being developed and will be formally submitted tcv Region III Regulatory Operations in response to a request by ,

them on this same subject. This ' program will be finalized by January 15, 1973.

Very truly yours ,

C0f@iONWEALTil EDISON COMPANY

QUAD-CITIES NUCLEAR POWER STATION e

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N 'B. B. Stephenson Supe rin tenden t -

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