ML20084C706

RO 250-74-2 & 251-74-2:while Conducting Normal Shutdown on Unit 3,turbine Stop Valves Failed to Close.Caused by Phosphate Deposits Between Valve Shafts & Bushings.Phosphate Buildup Problems Also Found W/Unit 4

ML20084C706
Person / Time
Site:	Turkey Point
Issue date:	05/30/1974
From:	Schmidt A FLORIDA POWER & LIGHT CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
RO-250-74-2, RO-251-74-2, NUDOCS 8304080174
Download: ML20084C706 (1)

Text

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Mr. John F. O' Leary, Director q[ g"kc}'.p,)

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Dear Mr. O' Leary:

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UNUSUAL EVENT NOS. 250-74-2 AND 251-74-2 TURKEY POINT PLANT UNITS 3 AND 4  :

TURBINE STOP VALVE MALFUNCTION DUE TO PHOSPHATE BUILDUP In accordance with Technical Specification 6.6.2b, the following unusual event is reported.

l Recently, while conducting a normal shutdown on Unit 3, the turbine stop valves failed to close. When all efforts to free the stuck valves proved unsuccessful, the valves were disassembled to deter-

".ine the cauce of the malfunction. Duasacably 4evealed

, phosphate deposits between the valve shafts and bushings. The j phosphate deposits were washed off with warm water and the valves l reassembled. The valves then operated satisfactorily. Subse-quently, phosphate buildup problems have been experienced with the l Unit 4 turbine stop valves. It was found that most of the phos-phate deposits could be removed by periodically flushing the valve shaft-bushing housing with warm water when the turbine is shutdown. The turbine manufacturer recommends performing a field modification to the valves which includes installing a larger diameter valve shaft and bushing assembly which is "self-c1 caning" when the valve is cycled. The modification on the Unit 3 turbine stop valves is scheduled to be accomplished ~during the October, 1974, refueling outage. The modification on Unit 4 will be scheduled during a maintenance outage this year.

Sincerely yours,

(&g-g/r

,. D. Schmidt Director of' Power Resources DNR/kmw cc: Mr. Norman C. Moseley Jack R. Newman, Esquire 5.1.81 8304000174 740530 V; gDRADOCK 05000250 COPY SENf MM - -

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