ML20084J547

AO-73-13:on 730621,during Power Operation,Diesel Generator 2 Failed to Fully Operate.Caused by Three Transformer Fuses Blowing During Lightning Storm.Two Fuses Replaced & One Jumped

ML20084J547
Person / Time
Site:	Oyster Creek
Issue date:	07/05/1973
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	Giambusso A, James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I), US ATOMIC ENERGY COMMISSION (AEC)
References
AO-73-13, NUDOCS 8305180163
Download: ML20084J547 (6)

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0 Jersey Central Powerj& Light Company

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. MADtSoN AVENUE AT PUNCH BOWL Ro AD e MoRRisToWN. N.J. 079sa e 539-6111 J

July 5, 1973 <

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_3 Mr. A. Giambusso JUL 9 1973 -

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Deputy Director for Reactor Projects Directorate of Licensing

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United States Atomic Energy Commission '% %d Sxnan Washington, D. C. 20545 y 8

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Subject:

Oyster Creek Station Docket No. 50-219 Diesel Generator .

The purpose of this letter is to report a failure of diesel generator No. 2 to be fully operable during power operation in that the diesel generator auxiliary power t.ruusformer fuses were t,lonn during a lightning stora in the vicinity of the plant. This event is considered to be an abnormal occurrence as defined in the Technical Specifications, Paragraph 1.15.D. Notification of this event as required by the Technical Specifications, Paragraph 6.6.2.a, was made to AEC Region I, Directorate of Regulatory Operations on Friday, June 22, 1973.

During a plant start-up, with plant electrical loads being supplied by off-site power, a lightning storm occurred in the vicinity of' the plant causing an cpparent voltage surge on the IB 4160v bus, resulting in blowing the three

. power transformer fuses for diesel generator No. 2. The result of this failure was to render the fuel oil transfer pumps inoperable since they are among auxiliaries supplied by_the transformer. Although the unit would have started and been oper-abic if a loss of off-site power had occurred, its fuel supply would have been limited to the quantity in the day tank.

As a result of a subsequent plant scram and the need to have both diesel generators operable to restart, two of these fuses were replaced (only two were in stock), the third jumped, and a satisfactory operability check was conducted.

Once the reactor had been made critical and the mode switch transferred to "run",

the fuse drawer was pulled out and the unit made' inoperable. Fuses were immediately ordered and daily surveillance testing of the other unit was implemented. ';

'Ihc significance of this event is the loss of redundancy of the AC l emergency power sourecs provided at the plant.

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• 6 S 05000219 PDR h 5306 -

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- COPY SENT REGION 7 l

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Mr. Gia:rbusso July 5, 1973 To prevent this type failure frou reoccurring, an investigation will be conducted to determine the mechanism which caused the blown fuse. The purpose of this investigation will be to determine if it is possible to provide pro-tection against a reoccurrence. In the meantine, an adequate supply of spare fuses will be maintained for the diesel generators to minimize the time required to return it to service.

Enclosed are forty (40) copics of this . report.

Very truly yours, O~rdcS Q G S5 i

Donald A. Ross ['U C Manager, Nuclear Generating Stations DAR:cs Enclosures cc: Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Region I

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Tot Jatms P. O'Reilit]

Directorate of Rcgulatory Oparations Rcgicn Z 970 Droad Street '

!!cuark, licw Jersey 07102  ;

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./ Prome Jorsay Central Powcr & Light Company

. Oyster Crcek fluclear Gcnorating Station Docket 0 $0-219 o Forked Rivers licw Jcracy 08731 l

SubjccLa Abnorr.a1 Occurrenco Roport _73-13 __ .

The folicving is a prolictinary report being subt:titted in compliance with the Tcchnical Spccifications l paragraph 6.6.2 I

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Dato t_ June 21, 1_97_1_ ,

Titte:__L1e25 p.m. _ _

ABt:C2F.AL CCCrn3I::CB f RFFORT 1:0._ 73 13 L iSUEJECT: Violation of the Technical Specification, para. _ _ .

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Failure ol _.Diesal Gennrator_H2 to be' fully operabia during power l opcration, in that pcuor transforcer fuses were bicwn during a '

• l lightning storm in the vicinity of the plant.

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This event is considered to bc an abnomal cccurren,co as define.d in the Techrtical Spicificat. ions, para.. 1,15,n . Hottrication or this c* rent as required by the Technical Spa:ctf tcatl' ens, para. 6.6.8 was nade to AEC Regicn I Directorate cf Regulatot/ Operations on -

Friday June 22, 1973_ __*

SITUATIC!T:

During a plant startup, with plant electrical 1 cads being supplicd by h off sito power, a lightning storen cccurred in tho vicinity of the plant causing an apparcnt voltage surge on the [B 4160v hus o resulting in blowing the three powcr transformerfuscs for Dicsci Generator d2. The result of this failurc was to cander the Fuel Oil Transfor Pumps in- l operabic since they arc among aupillarics supplied by *tiv3 crattsformar. l Althougin tho . unit would have statted and bcen operabic if a loss of l off cita pcwar had occurred, its Euct supply would have been Linited ,

to the quancity in the Day Tank. i

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?W Tha causa of this failura la thought to be as a result of a voltago surga which occurred an tha 1. H bus during a iE9 htning storn in the vicinity of the plant.

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i RDtCDIAL ACTION: h As a rcsult of a subacquent plant scram and the need to have both i

, 3 Dicsci Generators oporabia to rcstart, two of these fuscs stora rc~ t placed (only two wara in stackl, the third jumped,' and a satisfactory h opcrability check was inado once the storat had lef t tho arca. Once l l the reactor had been mado critical and the modo switch transfctred l to "RUl", the fusa drawor was pullod cut and the Unit trude inoperabla. )I 1

Vuses were Jr.mdiataly ordered and daily survoL11ance tcsting of the l l 'other unit was started. t

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4 JETT SIG?fIFICANCE: .

.. ..-. Thc. significance of this cvent is t a loss oE tcdundancy of' the AC cmergency power sources provided at the plant _.

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