ML20084E456
| 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: |
| References | |
| NUDOCS 8304150076 | |
| Download: ML20084E456 (2) | |
Text
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-ROCHESTER CA' AND ELEC1WC CORPORATION e 69 EAST !. VENUE, ROCHE$TER, N,Yl$N(d9
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May 30, 1973
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Mr.. Tames P. O'Reilly, Director i'
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970 Broad St.
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Deae Mr. O'Reilly; i
b During performance of the monthly surveillance procedure PT-5.2, "Undervoltage 2
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
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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.
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'1ho Pinnt Operating Review comittee reviewed the occurrence on S/30/73 and.
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approved a procedure for removing the undcrvoltage devices from service to -
y evaluate the cause of inoperability.
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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 y
secle accinmilation was removed and the plunner polished, subsequent bench 1
f testing of complete mechanism (plunger mounted in solenoid cotl), indicated
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fj freedom of movetnent of the plunger through the guide bearing, without noticable l
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upon returning the device to service, the applicable section of PT-5.2 procedure was perfortned to verify device operobility. As a precautionary measure,.the a
J remaining Reactor Trip Undervoltage devices were also removed and.disme.ntled-q for cleanup unintenanec.
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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
l The RtR.E t.:orporation De16y Department le investinat1Dg the prob 1cm with thir.
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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 problem.
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Charles E. Platt I
Superiitt4ndent
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