05000259/LER-1981-013-03, /03L-0:on 810424,Athens 161 Kv Line Tripped & Cooling Tower Transformer 1 de-energized.Caused by Rolled Current Transformer Leads B & C for Breaker 1928.Lead B in Breaker 1922 Loose.Rolled Leads Corrected

/03L-0:on 810424,Athens 161 Kv Line Tripped & Cooling Tower Transformer 1 de-energized.Caused by Rolled Current Transformer Leads B & C for Breaker 1928.Lead B in Breaker 1922 Loose.Rolled Leads Corrected

ML19347F853
Person / Time
Site:	Browns Ferry
Issue date:	05/19/1981
From:	TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19347F852	List: 05000259/LER-1981-013, Forwards LER 81-013/03L-0 05000259/LER-1981-013-03, /03L-0:on 810424,Athens 161 Kv Line Tripped & Cooling Tower Transformer 1 de-energized.Caused by Rolled Current Transformer Leads B & C for Breaker 1928.Lead B in Breaker 1922 Loose.Rolled Leads Corrected
References
LER-81-013-03L, LER-81-13-3L, NUDOCS 8105260471
Download: ML19347F853 (2)

LER-1981-013, /03L-0:on 810424,Athens 161 Kv Line Tripped & Cooling Tower Transformer 1 de-energized.Caused by Rolled Current Transformer Leads B & C for Breaker 1928.Lead B in Breaker 1922 Loose.Rolled Leads Corrected

Event date:
Report date:
2591981013R03 - NRC Website

text

9 rO M ass u. S. NUCLEA3 REGULATORY COMMISSION v"

LICENSEE EVENT REPORT CONTROL RLOCK: l l

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8 60 61 DOCKET NUMB ER 68 69 EVENT DATE 34 75 REPORT DATE 80 EVENT DESCRIPTION AND PROSABLE CONSEQUENCES h 10121 lWhen cooline tower switcheear "D" was transferred to normal feed breaker 1928 for

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1013] leurrent transformer wsing check as part of investigation for LER number BFRO l 1014 l 1259M1012. Athens l61 kv line tripped and cooling tower transformer 1 deenergized I

l o I S I l bv operation of "B" dif ferential relav (BDD 187 CT).

See T.S. 3.9.B.1.

Diesel l

1oI6I lgenarntors 1A. 1B. 3C. and 3D vere operable. There was no danger to the health or l

l0l7I ianfaty of the oublic.

Previous similar events

BFRO-50-259/8059, 81012.

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CAUSE COMP.

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l Iiii1 !were found roll'ed for breaker 1928. A "B" phase current transformer connection

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t iii31 lwas also discovered loose in normal feed breaker 1922 for 4 kv cooling tower switch- ;

y l gear A.

The loose connection was tightened and rolled leads were corrected.

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Tennessee Valley Authority Form BF-17 Browns Ferry Nuclear Plant BF 15.2 3/24/81 LER SUPPLEMENTAL INFORMATION BFRO ?59 /, 81013 Technical Specification Involved 3.9.B.1 (U2) (U3)

Reported Under Technical Specification

6. 7. 2.b (2)

Date of Occurrence 4/24/81 Ti.ne of Occurrence 1520 Unit 0

Identification and Description of Occurrence:

Returning CT switchgear "D" to service, when ACB 1928 was closed it tripped the Athens 161 kV line.

Conditions Prbr to Occurrence:

r Unit 1 rein.,iing outage.

thit 2 at 99%

thit 3 at 91%

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Action specified in the Technical Specification Surveillance Requirements met gue to inoperable equipment. Describe.

Isolated CT transformer switchgear D-U-3 D/G SI's already completed. Unit 1 and 2 diesel generator SI's were not performed (Reference BFRO-50-259/81017).

l l

l ppi arent Cause of Occurrence:

"B" phase current transformer lead (1TC2) and "C" phase transformer lead (ICT03) l were rolled for breaker 1928. The "B" phase current lead in breaker 1922 was l

also loose. Current transformer leads have apparently been rolled since construction.

Analysis of Occurrence:

There was no danger to the health or safety of the public, no release of activity, no damage to the plant or equipment, and no resulting significant chain af events.

l l

Corrective Action

"B" and "C" phase current transformer leads were rs J ed for breaker 1928. The loose "If' phase lead on breaker 1922 was tightened. The correct phasing of current transformer for cooling tower transformer 1 breakers 1922, 1924, and 1928 was verified. This is considered random failure, however, phasing of current trans-formers 1920, 1916, 1918, 1930, 1912 and 1914 will be verified during the next extended unit 2 outage.

Failure Data BFRO-50-259/8059, 81012.

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• Retention : Period - Lifetime; Responsibility - Document Control Supervisor

• Revision :

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