ML19344F120

LER 80-139/03L:on 800807,during Operation in Mode 2,B Train Transfer Switch for Component Cooling Water Pump Supply Tripped on Three Occasions.Caused by Thermal Overload Assembly.Switches Modified by Defeating Overload Features

ML19344F120
Person / Time
Site:	Sequoyah
Issue date:	09/04/1980
From:	Kirk G TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19344F103	List: ML19344F102 ML19344F120
References
LER-80-139-03L, LER-80-139-3L, NUDOCS 8009120440
Download: ML19344F120 (2)

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io ;2l EV l During NT normal DESCRIPTION operation in Mode AND2,PROBASLE the CONSEQUENCES train transfer switch for the Component h 'B' J

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LER SUPPLEMENTAL INFORMATION

" SQRO-50-327/80139: ' Technical Specification Irvolved 3.7.3.l'

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Reported Under Technical Specification' 6.9.1.13.b Date of Occurrences: 8/07/80 . Times of Occurrences: 1310 CDST 8/10/80 1900 CDST 8/11/80 1430 CDST l

- IdentificationandDescridtionofOccurrences:

> 1. On 8/07/80 at 1310 CDST during normal operation, the Component Cooling. Water Pump C-5 would not start when Unit 2 Operator attempted to start the, pump in preparation for a preoperational test on shutdown board 2B2-B. The system was declared inoperable and the action statement of LCO 3.7.3.1 was

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Investigation revealed that the 'B' train transfer switch was open. The ASE closed the-switch at 1312 CDST, started the pump at 1320 CDST, and declared  !

the system operable. ' Earlier at 1230 CDST the ASE had verified the transfer switch alignment. . The cause of the switch being open was unknown.

i i 2. On-8/10/80 at 1900 CDST during normal operation, the Component Cooling Water Pump C-S 'B' train transfer switch was found tripped. The system was declared i- inoperable and action statement of'LCO 3.7.3.1 was entered.

The transfer switch was reset and the pump was started. The system was declared' operable at.1919 CDST. The cause of the open switch could not be determined.

3. On 8/11/80 at 1430 CDST during normal operation, the component Cooling

' Water Pump C-S ':B' train. transfer switch was discovered tripped. The system was' declared inopersbie and action statement of LCO 3.7.3.1 was entered.

-Investigation revealed ~ that the transfer switch contains a thermal overload

'- assembly. The overload. assembly is not specified on the design drawings.

The overloads were' replaced and-the pump returned to service.at 2350 CDST while an investigation was being made to determine if the design drawing was correct.-

Conditions Prior to occurrences:

Mode-2t 4% Power

' Apparent-Cause of Occurrence:

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_ Improper switch-installed during construction. 13de transfer switch should not have a-thermal = overload assembly..

Follow-Uo Corrective Action:

The 'A' and4'B'; train transfer. switches will be modified by defeating their thermal overload' features.'

Failure-Data':

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