05000366/LER-1980-048-03, /03L-0:on 800415,while Checking Wiring Changes Made During Emergency Bus Alternate Supply Breaker Mod, Current Transformer Terminal Block 3 Found Burned at Termination Points.Caused by Loose Connection in Circuit

/03L-0:on 800415,while Checking Wiring Changes Made During Emergency Bus Alternate Supply Breaker Mod, Current Transformer Terminal Block 3 Found Burned at Termination Points.Caused by Loose Connection in Circuit

ML19309H212
Person / Time
Site:	Hatch
Issue date:	04/29/1980
From:	Nix R GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19309H205	List: 05000366/LER-1980-048, Forwards LER 80-048/03L-0 05000366/LER-1980-048-03, /03L-0:on 800415,while Checking Wiring Changes Made During Emergency Bus Alternate Supply Breaker Mod, Current Transformer Terminal Block 3 Found Burned at Termination Points.Caused by Loose Connection in Circuit
References
LER-80-048-03L, LER-80-48-3L, NUDOCS 8005090364
Download: ML19309H212 (2)

LER-1980-048, /03L-0:on 800415,while Checking Wiring Changes Made During Emergency Bus Alternate Supply Breaker Mod, Current Transformer Terminal Block 3 Found Burned at Termination Points.Caused by Loose Connection in Circuit

Event date:
Report date:
3661980048R03 - NRC Website

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REPoRr o4TE 80 60 65 occKET NuM.ER EVENT DESCRIPTION AND pro 8 ASLE CONSEQUENCES h 7

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With the reactor in cold shutdown, while ch'ecking the wiring changes made o 2 i l

' during the Emergency Bus Alternate Supply Breaker Modification, the cur-gl 1

rent transformer terminal block in Junction Box 2JESB02 was found to be lT]T) I i l Relay

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~ burned at 'the terminal points for the Overcurrent and Different a gi 1

Circuits that monitor the normal and alternalte supplies for Emergency o s l l

Neither public health and safety nor continued safe plant i

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The overheating was caused by a loose connection in the Overcurrent Relay l

g1 Circuit at Terminal Block-3. The affected circuits were removed from term-t i

l Current trans-g inal block-3 and spliced to prevent a possible failure.

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i 15, 1980, while making a verification 4... v.With the reactor in cold shutdewn on April of the wiring changes that were made for the Emergency Bus Alternate Supply

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',, g. ~-Breaker Modification, tenninal block-3 in Junction Box 2JESB02 was found

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burned at the termination points for the Overcurrent Relay Circuit, which

/. monitors the normal supply for Emergency Bus "2F" from the 2D Start-up

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....: Transformer. Although there was heat damage to this circuit and some i

i hich monitors the F '^ heat damage caused to the Differential Relay C rcu t, w alternate supply for Emergency Bus "2F" from the 2C Start-up Transformer, lthere,were no failures as continuity still existed across the terminal block.

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..The overheating was apparently caused by a loose connection in the Over-i current Relay Circuit at terminal block-3. The two affected circuits were

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, removed from terminal block-3 and spliced to prevent the possibility of a future failure. An inspection was then made of the current transformer

' connections in Junction Boxes 2JESB02 and 2JESB10 to ascertain that this.

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was a singular incident.

. Neither public health arJ safety nor continued safe plant operation was

~.'J.*"'",~~ ' af fected by this occu"m a.

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