ML20084A725

AO 75-12:on 750725,during Monthly Surveillance Procedure PT-9,undervoltage & Underfrequency Protection,Primary Undervoltage Device 273/11B Armature Did Not Drop Down to Assume de-energized Position.Caused by Scale Accumulation

ML20084A725
Person / Time
Site:	Ginna
Issue date:	07/25/1975
From:	Lang L ROCHESTER GAS & ELECTRIC CORP.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20084A720	List: ML20084A725
References
AO-75-12, NUDOCS 8304050572
Download: ML20084A725 (1)

Text

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ROCHESTER GAS AND ELECTRIC CORPORATION e 69 EAST AVENUE, ROCHESTER, N.Y. lY49

• ta t e rwo .c anta coor m 546 27oo Ginna Station

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July 25, 1975 I

Mr. James P. O'Reilly, Director E J{,)

.. 3 Directorate of Regulatory Operations .

Region I -

H . 3301975 '

U. S. Atomic Energy Commission .

631 Park Avenue A "

King of Prussia, Pa. 19406 C

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Sub,1ect: Abnormal Occurrence 75-12: Failure of Undervoltage Relay During Monthly Surveillance Test ,

Ginna Station i l

Docket #50-24h ,i

Dear Mr. O'Reilly:

During the performance of the Monthly Surveillance Procedure FT-9, "Under-voltage and Underfrequency Protection" on July 25, 1975, upon opening the knife switches for the solenoid coil of primary undervoltage device 273/11B, it was discovered that the device armature did not drop down to assume its' de-energized position. As a result of this failure to operate, the Reactor l Trip Undervoltage Protection signal was not generated to this relay. The knife switches were in: mediately opened again, and this second time the relay operated properly. The other three undervoltage relays on the 4160 volt bus were tested and they operated properly, i .

l R'G & E Relay Department was contacted and a relay man cane to the station to

! investigate the failure.

':. A scale accumulation was noted on the armature plunger opposite the area of f'

the upper guide bearing. This accumulation was similar to that reported as

, abnormal occurrence 73-1 on May 29, 1973.and 7h-19 on December 5, 1974. All

' four undervoltage relays were removed, one at a time, and the scale accumulation

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l? was removed and the plunger polished. Upon returning the devices to services, the applicable section of PT-9 procedure was performed to verify operability.

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Very truly yours,.

DR O a S A,,, -' '

Lee S. Lang Assistant Superintendent n ec: Mr. J.F.0' Leary,'NRC Mr. G.J.Swarthout, RG&E _. ...

Mr.:L.D.Whitc,;Jr. RG&E. .

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