ML20084E456

Ro:On 730529,upon Opening Knife for Solenoid Coil of Primary Undervoltage Device 273/IIA,device Armature Discovered Not Dropping Down to Assume Deenergized Condition.Caused by Scale Accumulation on Device.Investigation Continuing

ML20084E456
Person / Time
Site:	Ginna
Issue date:	05/30/1973
From:	Platt C ROCHESTER GAS & ELECTRIC CORP.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20084E438	List: ML20084E436 ML20084E456
References
NUDOCS 8304150076
Download: ML20084E456 (2)

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-ROCHESTER CA' AND ELEC1WC CORPORATION e 69 EAST !. VENUE, ROCHE$TER, N,Yl$N(d9 r

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May 30, 1973

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'. e i 4 Mr. . Tames P. O'Reilly, Director i j Region-), Divinion of Compliance

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s Deae Mr. O'Reilly; i b ,

2 During performance of the monthly surveillance procedure PT-5.2, "Undervoltage

! ij and tinderirequency Protectf on" on 'i/29/73, upon opening the knife switches for j the solenoid coil of primary undervoltage device 273/11A, f t van discovered

• that the device arusture did not drop down to anatune its' de-energized condition.

a As a result of this failuro to operato the Reactor Trip Undervoltage Protection Signst was not generated from this unit,

..$. This undervoltage device, 273/11A, is one of two for the 11A, 4160 voit bus.

J At the tirne of inoperabi.lity of device, 273/ilA, the redundant relay, 274/11A,.

-j did operate satisfactorily, additionally both Reactor Trip Undervoltage Devices 3 for 11B, 4160 volt bus functioned currectly, b

] Undervoltage Reactor Trip Logic is 1/2 + 1/2 fro:n both 4160. volt busses and

. this capability was not trapsf red am s result or the one ualfunctioning device j.-t on 4160 volt hus 11A.

i '1ho Pinnt Operating Review comittee reviewed the occurrence on S/30/73 and .

? approved a procedure for removing the undcrvoltage devices from service to -

r y evaluate the cause of inoperability.

t lipon inspection of the concerned 4cvice (273/11A) a scale accumulation was noted j on the armature plunger opposite the cres of the upper guide bearing. The 1

y secle accinmilation was removed and the plunner polished, subsequent bench

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f testing of complete mechanism (plunger mounted in solenoid cotl), indicated fj freedom of movetnent of the plunger through the guide bearing, without noticable l drag, t

upon returning the device to service, the applicable section of PT-5.2 procedure a was perfortned to verify device operobility. As a precautionary measure,.the . ,

J remaining Reactor Trip Undervoltage devices were also removed and .disme.ntled-q for cleanup unintenanec.

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t Prior to YOiU8talling the protectiVt: device 0 O e411bratiO11 Uno applied tn

!; intuire t. hat the devices would trip when the applied voltage van reduced to the ij device trip point netting, e

e l The RtR.E t.:orporation De16y Department le investinat1Dg the prob 1cm with thir.

Y typa of relay and they ui.ll be report' inn back to the Plant Operating Revieu ConmLLlee with their recomendation l'or preventing a recurrence of thio

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