ML19331B658

LER 80-014/03L-0:on 800709,transformer T4 of Diesel Generator 1 Failed.Caused by Shorted Coil.Transformer Replaced

ML19331B658
Person / Time
Site:	Fort Calhoun
Issue date:	08/01/1980
From:	Mueller R OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19331B650	List: ML19331B649 ML19331B658
References
LER-80-014-03L, LER-80-14-3L, NUDOCS 8008120552
Download: ML19331B658 (4)

Text

NRC FOIM 384 U.S. NUCLEAR RE ULATcRY COMMISSION (7

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• LICENSEE EVENT REPORT CONTROL BLOCK: l 1

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60 81 DOCK ET NUM8ER 68 89 EVENT DATE 74 75 aEPORT DATE 80 EVENT DESCRIPTION AND pro 8ABLE CONSEQUENCES h t o # 2l l Transfonner (T4) of DG-1 failed. This transformer fed onwar to the dipep1's nil im l

[o tai i mersion hsater as well as alarm circuitry correspondino to the followina items: I i o 141 l Low lube oil pressure, Low lube oil level, and Hioh or Low lube oil temoerature. I io isi i During the thne of the transformer (T4) failure,- DGt-2 as well as the 161KV and 345 KY Io is I I systems were available and operab_le and would have been more than caoable of miti- I 1o17) ! gating.the circumstances of an accident should.the need arise. _In additio.n..DG-1 I was considered inoperable only during the time that the transformer was being i o is i , changed out, i.e. only while DG-1 was in " local maintenance". ,,

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_ l35Z lg lMZl@ 31 40 41 4 43 M 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 27 li)oll The transformer failure was caused by a shorted coil. The transformer was replaced I with an equivalent component and subsequently the diesel generator, immersion heater and all transformer related annunciation circuitry was satisfactorily tested and I mi

,,,,,l returned to operation. The replacement transformer although eletrically equivalent !

was of a different manufacturer. Thus an exact replacement transformer or the trans1 yl rormer wr:cn nas supercedec it will be procurred and installed as soon as time l

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LER 80-014 Omaha Public Power District Fort Calhoun Station Unit No.1 Docket No. 05000285 ATTACHMENT NO.1 Safety Analysis The Fort Calhoun Station Unit No.1 F.ngineered Safety Features System is so designed that no single failure can prevent the safe shut-down of the plant if necessary. During the time diesel generator DG-1 was inoperable, diesel generator DG-2 was operable as were the 161 KV and 345 KV supplies thus providing more than adequate capability for safe shutdown of the plant should the unlikely event of an accident occur.

It should be pointed out that DG-1 was considered inoperable only during the time that the transformer was being changed out since this transformer only feeds the oil immersion heater for DG-1 and associated annunciation. Should the need have arisen, DG-1 would still have automatically started per engineered safeguards and performed its design function as described in the Final Safety Analysis Report.

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LER No.80-014 Omaha Public Power District '

Fort Calhoun Station Unit No.1 Docket Ns. 05000285 ATTACHMENT NO. 2 Corrective Action M.0. #6421 was written to replace tfm failed Westinghouse 480/120, 100 Va, Model 2-F-47-1 transfonner. Since Westinghouse no longer manu-factures this transfonner, (it was superseded by their model 1F0892) and no exact duplicate / spare was available, it was replaced using an equivalent GE 100 Va, 480/120 volt transformer. Upon replacement, the diesel was tested satisfactorily for operation as was all transfonner related circuitry and the diesel DG-1 was returned to service.

As a further note, the Westinghouse model 1F0892 transfonner which has superseded the failed model 2-F-47-1, and is electrically equivalent or superior to the model 2-F-47-1 has been ordered and will be installed in DG-1 circuitry as soon as procurement allows.

LER No.80-014 Omaha Public Power District . 1 Fort Calhoun Station Unit No.1 Docket No. 05000285 ATTACHMENT NO 3 Failure Data This is the first failure of this type at the For: Calhoun Station.

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