ML20084C665

ROs 250-74-3 & 251-74-3:capacitor Failures in Rod Control Power Supply Filter Assemblies Caused Control Rod Drops, Initiating Turbine Runbacks.Cause Unknown.Investigation in Process by Vendor

ML20084C665
Person / Time
Site:	Turkey Point
Issue date:	07/15/1974
From:	Schmidt A FLORIDA POWER & LIGHT CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084C659	List: ML20084C665
References
RO-250-74-3, RO-251-74-3, NUDOCS 8304080146
Download: ML20084C665 (1)

Text

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, . e .: i Lq1y 15, 1974

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Mr. John F. O' Leary, Director ,3 JUL2 0 737'/ .%

Directorate of Licensing (.y t.. . .v# nr kSj Office of Regulation b rC U. S. Atomic Energy Conmission  % -

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Washington, D. C. 20545 x ],f

Dear Mr. O' Leary:

UNUSUAL EVENT NOS. 250-74-3 AND 251-74-3 ,

TURKEY POINT PLANT UNITS 3 AND 4

. UTILIZATION OF 151 PROPER CAPACITORS JP THE RuD L% i mL C16"' ' S In accordance with Technical Specification 6.6.2b, the followin; unusual event is reported:

b' Capacitor failures in the rod contrel power supply filter assemblies have caused car. trol rod drous which have initiated turbine runbacks.

These capac1Luin aie used in the mv ohlu and ,Latianary f,rippcr coil; 4 of the control rod drive mechanism. They are manufactured by the Mid-wec Company and use mylar as the dielectric material. The capacitors failed because they were unabic to withstand the voltage spikes i.

herent in the stationary gripper thyrictor circuits. ,

The problem has been taken up wiC 'he .. > .in & '

,e vestigating a suitable replac ciaen t capacitur. Until a replatein s t been found, the reactor vendor recommended that the capacitors be dis connected from the circuit, as this would not prevent the rod contrel

< circuitry from performing its intended safety function. Th'is rec-e ommendation was implemented as a special test to be conducted until the arrangement either proves unsatisfactory or a replacement is available. The capacitors were disconnected from Units 3 and 4 on )

June _12, and 17, 1974, respectively.

Sincerely youn T /,:,/ j/-

,//;',?u (A.o. w. on g (f, l Directo: of Pcwo Re..cu rc e s t p'g 1 D',iN /1.cm i ,I,) ,' (/1, 3; / l i sty y%

cc: 3!:. Norman C. 'to::c l e y Jack R. Newman, Esquire

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8304080146 741009 DR ADOCK 05000250 p

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