ML20024C393

Interim Deficiency Rept Re Malfunction of Limitorque Valve Operator.Initially Reported on 830526.Investigation Continuing to Confirm Extent of Problem & Determine Corrective Action.Final Rept to Be Submitted by Fuel Load

ML20024C393
Person / Time
Site:	Diablo Canyon
Issue date:	06/27/1983
From:	Schuyler J PACIFIC GAS & ELECTRIC CO.
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
10CFR-050.55E, 10CFR-50.55E, NUDOCS 8307120582
Download: ML20024C393 (2)

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Docket No. 50-323

, *rv 50.55(e) Report i SD PACIFIC G-A S AND ELECTR,IC C O /$j[ ANY wy bbM l 77 BEALE STREET . S AN FRANCISCO, CALIFORNI A 94106 * (415) 781 4211 . TWX 910 37 f//[,-

J.o.scHuyten b,t pp W.Ct Pet 1lCf 47 avCLtaa Poeta st%taaT504 June 27, 1983 Mr. John B. Martin, Regional Mministrator U.S Nuclear Regulatory Cnmicision, Region V 1450 Maria lane, Suite 210 Walnut Creek, CA 94596-5368 Re: Docket No. 50-323 Diablo Canyon Unit 2 10 CER 50.55 (e) Report -

Malfunction of Limitorque Valve Operator

Dear Mr. Martin:

On May 26,1983, Mr. Morrill of your office was notified by telephone of a problem concernitw binding of a torque switch on an operator manufactured by Limitorque against the switch assembly mounting bolts.

When Region V was originially notified of this event, it appeared that the cause was manual overtorquing of the valve operator, resulting in the torque switch arm wedging against the mounting bolt.

'Ibe proposed corrective action at that time was to replace the existing mounting bolts with round head bolts with a split lock washer.

Subsequent investigation in conjunction with Limitorque, however, indicates that there is a need to evaluate the cause of the event in greater detail to prevent exacerbating the situation and to identify the specific valves susceptible to this phenomenon.

Investigations to date indicate that the problem has only occurred on one valve, and preliminary analysis showed that it occurred frtxn overtorquing. However, PGandE has only been able to duplicate the problem on other valvas by manually manipulating the torque switch, not by any actual operation. Limitorque does not believe that the torque 1 switch can actually move far enough to bind during actual operation. I PGandE is continuing the investigation in conjunct?on with Limitorque to I confirm the extent of the probl.em arxl determine an appropriate corrective  !

action. I In view of the above, please regard this as an interim report; a l final report will be submitted once the investigation to establish the cause, corrective action, and generic implication is completed.

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8307120582 830627 PDR ADOCK 05000323 l 10  !

S PDR D'YL

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Corrective actions will be empleted and a final 50.55(e) report subnitted before Unit 2 fuel load.

Sincerely, cc: Mr. G. W. Knighton, 011ef Licensing Branch No. 3 Division of Licensing Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory enantasion Washington, D. C. 20555 Service List 4

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