ML20236U010

PN-75-009:on 750402,Region III Notified That Bus Fault Occurred at Kewaunee Nuclear Plant Main Auxiliary Transformer.Cause of Fault Not Yet Determined.Bus Fault Resulted in Trip of Generator

ML20236U010
Person / Time
Site:	Kewaunee
Issue date:	04/03/1975
From:	Jennifer Davis, Thornburg H, Warnick R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:
References
PN-75-009, PN-75-9, NUDOCS 9807290252
Download: ML20236U010 (1)

Text

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fDR adV.t G %_ fn 5 v.9 s PRELIMINARY NOTIFICATION - NOT FOR PUBLIC DISCLOSURE April 3, 1975 l^ PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PN-75-09 This preliminary notification constitutes EARLY notice of events of POSSIBLE sr.fett or public interest significance. The information presented is as initially received without verification or evaluation l and is basically all that is known by OIE staff as of 1:00 p.m. on l

date of this notification. IT SHOULD BE SPECIFICALLY NOTED THAT THIS NOTIFICATION MAY CONTAIN INFORMATION THAT LATER MAY BE DETERMINED TO BE INACCURATE OR INCONSISTENT. AN OFFICE OF INSPECTION AND ENFORCEMENT NOTIFICATION OF AN INCIDENT OR OCCURRENCE (BLUE SHEET) SUBSEQUENTLY WILL BE ISSUED IF WARRANTED.

~Tacility: Kewaunee Nuclear Power Plant, Wisconsin Public Service Corp.

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Subject:

'dAIN AUXILIARY TRANSFORMER BUS FAULT Our Region III (Glyn Ellen, Illinois) office was notified on April 2,1975 that a bus fault had occurred at the Kewaunee nuclear plant Main Auxiliary Tranformer (20 KV/4.16 KV) at 10:00 a.m. on April 2, 1975.

The cause of the fault has not yet been determined.

The bus fault resulted in a trip of the generator which in turn caused the turbine and reactor to trip. All equipment and systems functioned as designed and the loads being carried by the Main Auxiliary Transformer _,;

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vere automatically switched to backup transformers. Power to and within S the plant was riever interrupted. There were no radioactive releases.

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t The fault on the 4160 V side of the transformer melted two inches of two busses, damaged the third bus, and melted some of the bus duct. The water spray system at the transformer was automatically activated.

Heat from the fault was transferred through the turbine building wall bus penetration and caused smoke inside the building, localized damage to the bus tray, and damage to 30 feet of bus insulation.

Although the event was not required to be reported to the Commission, the plant notified Region III at about 4:00 p.m. on April 2, 1975.

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As permitted by Technical Specifications, reactor operation was resumed about midnfght on April 2, 1975.

b j Based on information received from our resident inspector, the reactor safety implications of this event are minimal. We are distributing ~

this information because of the current interest in electrical fires.

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Contact:

RFWarnick, IE x7261 HDThornburg, IE x7353, JGDavis, IE x7341 0'

@ Distribution:

b Chairman Anders Commissioner Mason Secretary C tv Cou:missioner Gilinsky Commissioner Rowden JCAE ,

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.ch$* Commissioner Kennedy Congressional-M i -.

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s D b b R. V. Gossick, EDO B. C. Rusche, NRR D. F. Knuth, IE H. H. Brown, ISP J. A. Harris, PA j; f o 2

,J.R. Chapman,NMSS H. K. Shapar, ELD

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Transraitted: P Bldg )p  ; H St .3 p

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