ML20085K232

Ro:On 730528,during Surveillance of Automatic Pressure Relief Sys,Valve 203-3A Failed to Operate.Investigation Revealed That Distortion of Gasket Affected Operation of Valve.Gasket Removed

ML20085K232
Person / Time
Site:	Dresden
Issue date:	06/20/1973
From:	Worden W COMMONWEALTH EDISON CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
467-73, NUDOCS 8310200358
Download: ML20085K232 (2)

Text

gC3 Comm calth Edison 4 m1 93_ pts [_ y_L_ layP Ch(caco, Ili

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Chicado, Illinois 60600 50-249 WFW Ltr.f'57-73 Dresden Nuclear Power Station R. R. #1 .

Morris, Illinois 60450 June 20, 1973 W ~

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Mr. A. Giambusso 2 JUr1231973> _.

Deputy Director for Reactor Projects 6' t.s.grym Directorate of Licensing e gwy U. S. Atomic Energy Co:rmission  % N 3C8 Washington, D. C. 20545 #

N 01 SUEJECT: LICENSE DPR-25, DRESDEN 7:UCLEAR PC'RR STATION, UNIT #3 SECTION 6.6.C.1 0? THE TEC~lNICAL SPECIFICATIONS. *

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Dear Mr. Ciambusso:

This is to report a condition relating to the operation of the unit in which, during a surveillance of the Automatic Pressure Relief System valve 203-3A failed to operate. Ihis condition was reported to Mr. Fred

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' ' ' ' ' Haura of Region III' Regulatory Operations via Yelephons 6n'May '29,1973. ' !

i i PROBLEM AND INVESTICATION (Reference P & ID M-345)

On May 28, 1973 at 0630 hours0.00729 days <br />0.175 hours <br />0.00104 weeks <br />2.39715e-4 months <br />, the unit was heating up following a maintenance outage with the mode switch in the " START" position, reactor l pressure at 240 psig, and reactor water level at 30 inches. As required I by Technical Specifications Section 3.5.D.1, the operability of the Auto-

• mati.c Pressure. Relief, System was.being checked. When the automstic pressure,,

relief valve 203-3A was tested, its pilot valve functioned as indicated by an "OPEN" light actuated in the control room but the main valve showed no indication of operating (i.e., no valve discharge temperature change and no surge in reactor water level.) Although the Technical Specifications Section 3.5.D.2. allows operation for thirty days with one automatic relief valve inoperable (the High Pressure Coolant Injection System operability had been demonstrated earlier in the heat-up), an orderly shutdown and cooldown was performed so that relief valve 203-3A could be repaired. The reactor was shutdoms and below 90 psig at 0918 on Pay 28,1973. ,

l EVALUATIONS AND CORRECTIVE ACTIONS The Auto =atic Pressure Relief System is designed such that four -

of the five installed relief valves will provide adequate pressure relieving capability. Therefore, loss of one valve does not materially affect the operating safety of the reactor plant. In additio , the immediate cessation

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• Wr. A. Giamb.usso June 20, 1973 of reactor startup in order to repair the valve provided an extra margin of safety even though it was not specifically required by the Technical Specifications.

Following reactor cooldown, the discharge elbow on relief valve 203-3A was removed so that the valve internals could be inspected. A 3/16" thick full-face asbestos gasket was found installed on the discharge side of the valve. The gasket had been used in conjunction with a blind flange and another gasket to seal the discharge of the valve earlier in the maintenance outage. Prior to start-up, the blind finnge and one gasket had been recoved but this gasket was inadvertantly left in the valve dis-charge. Distortion of.the gasket showed that valve 203-3A had, in actuality, operated when tested but due to the thickness of the gasket and the low reactor pressure, the valve experienced no flow.

The full-face gasket was removed and the discharge elbow reassem-bled. Valve 203-3A was subsequently rctested and performed satisfactorily.

It should be noted that since the gasket was deformed at 200 psig, sufficient pressure would have existed under operating conditiens to burst the gasket and thereby allow the valve to relieve reactor pressure. Also, the other four relief valves in the system were denonstrated to be fully operational

, ,_ and, were capcale of providing 100~. of design .pressurc relicying . capacity, s ,

Since this is the first time this type of problem has arisen, no maintenance procedure changes have been issued. Ilowever, the personnel involved have been cautioned to be more careful in the future and to ensure that maintenance on a system or co=ponent is indeed complete prior to releasing it for operation.

Sincerely, I.bc S \ W. P. Worden Superintendent WFW:do