ML20085D095

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Responds to 730713 RO Bulletin 73-02, Malfunction of Containment Purge Supply Valve Switch. Purge Sys Meets Design Requirements & Needs No Mod
ML20085D095
Person / Time
Site: Robinson, 05000000
Issue date: 08/07/1973
From: Utley E
CAROLINA POWER & LIGHT CO.
To: Moseley N
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20085D093 List:
References
REF-SSINS-6820 IEB-73-02, IEB-73-2, NG-73-260, NUDOCS 8307200387
Download: ML20085D095 (3)


Text

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Carohna Power T. Light Company August 7, 1973

-File: 5211.2 Serial: NG-73-260

^

Mr. Norman C. Moscicy '

Directorate of Regulatory Operations U. S. Atomic Energy Commission ,

Region II - Suite 818 230 Peachtree Street, N.W.

Atlanta, Georgia 30303

Dear Mr. Moseley:

H. B. ROBINSON UNIT NO. 2 LICENSE NO. DPR-23 DRO BULIETIN No. 73-2 MALFUNCTION OF CONTAINMENT PURGE SUPPLY VALVE SWITCH In response to your letter of July 13, 1973, concerning DRO Bulletin No. 73-2, a review of the control circuit for the containment ventilation system isolation valves was made.

The review indicated the Robinson Unit 2 purge valve control system is unlike that of Point Beach 2 described in your bulletin. The purge valve control system and the two identical control systems for the two purge fan motors are interlocked. Turning a momentary contact switch on either of the fan control systems will automatically open the purge valves and start the fan motors. Thece switches on the fan control systems are the only means of manually opening the purge valves. Connected in series with the solenoid relays which actuate the valves are two sets of normally closed relay contacts. On receipt of a containment isolation signal or a signal from the radiation monitoring system these contacts will open, de-energir.ing the solenoid relays and closing the purge valves.

In the event that the control switch which manually operates the exhaust fan motors (and, consequently, the purge valves) failed such .

that these valves could not be closed from this switch, a containment isolation signal or a radiation monitoring system signal would independently close the valves. Therefore, under normal operating situations one of these two systems could be manually actuated from the control room to close f the isolation valves until repairs could be made on the failed switch.

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O O Mr. Norman C. Moscicy August 7, 1973 In an accident situation the valves would automatically close on receipt of a signal from these systems despite the failed switch.

We believe that our purge system meets the design requirements and needs no modification.

Yours very truly, hb E.

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't. Uticy  ;[

Vice-President Bulk Power Supply KPY:NBB:mvp cc: Messrs. C. D. Barham N. B. Bessac B. J. Furr D. V. Menscer D. B. Waters

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