ML19337A342

LER 80-059/03L-0:on 800810,during Normal Operation,Lightning Caused Athens 161 Kv Line to Trip Momentarily.Cooling Tower Transformer Tripped,Causing Loss of 4 Kv Tie Board.Cause of Transformer Trip Unknown.Athens Line re-energized

ML19337A342
Person / Time
Site:	Browns Ferry
Issue date:	09/04/1980
From:	TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19337A338	List: ML19337A337 ML19337A342
References
LER-80-059-03L-01, LER-80-59-3L-1, NUDOCS 8009090565
Download: ML19337A342 (2)

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[o l:] l During normal operation, lightning apparently caused Athens 161 kV line to trip

[o; ; gomentarily. Af ter one minute cooling tower transformer No. 1 tripped causing loss g.g gf Unit 3 4 kV bus tie board. After about 30 minutes the transf ormer was reener3Med ,

I g .] gnd it tripped again. Transformer was removed from service for testing and Athens ,

Io1+] ! 161 kV line reenergized. Diesel generators were available. No danger to health or j o l ] l safety of public. No previous occurrences. Re fe rence T. S . 3. 9. B.1.

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..- t iinnessee Valh y Authority Form DF-17

. Browns Ferry Nuclear Plant BF 15.2 1/10/79 LER SUPPLEMENTAL INFORMATION BFRO-50 3.9.B.1 259 / 8C59 Technical Specification Involved Repo'rted Under Technical Specification 6. 7. 2. M 2) .

Date of Occurrence 8/10/80 1639 1 Time of Occurrence _ Unit Identification and Description'of' Occurrence: During normal operation, lightning apparently_ caused the Athens 101 KV line to trip momentarily. Af ter about 1 minute cooling tower transformer No. 1 tripped causing a loss of Unit ,3 4 KV bus tie board.

After about 30 minutes the transformer was reenergized and it tripped again about 1 minute later. .There was no indication that protective current or sudden pressure relays had operated. The transfomer was removed from service for testing and the Athens 161 KV line reenergized.

Condicians prior to Occurrence:

Unit 1 @ 73%

Unit 2 @ 96%

Unit 3 @ 94%

Action :;pecified in the Technical Specification Surveillance Requirements met

!)up to inoper,61e equipment. Describe.

Diesel generators operable Apparent Cause of Occurrence: '

There was no indication of what tripped the transformer. No circuit probless were found which could have tripped the transformer.

,lnalysis of Occurrence:

There was no damage to plant equipment. There was no activity release, no personnel exposure or injury and no danger to the health or safety of the public.

Corrective Action:

All current. relays aad the transformer were tested. Trip indicators were verified operable. Af ter all transformer tests were completed the transformer was reenergized and loaded on 8/11/80. This appears to be a random trip and the trip circuit and feeder transfer scheme will be rechecked when permissible by Technical Specifications.

Athens 161 KV 'line was temporarily removed from ervice in order to reenergize the cooling tower transformer.

Failure Data:

N/A TRetention : . eriod - Lifetime; Responsibility - Administrative Supervisor

• Hevision : . g\ / 5 Q/

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