05000327/LER-1980-166-03, /03L-0:on 800927,during Normal Operation in Mode 4,output Breaker for Vital Inverter 2-IV Tripped Rendering Vital Instrument Power Board 2-IV Inoperable.Caused by Bad Auxiliary Switch on K1 Relay.Auxiliary Switch Replaced

/03L-0:on 800927,during Normal Operation in Mode 4,output Breaker for Vital Inverter 2-IV Tripped Rendering Vital Instrument Power Board 2-IV Inoperable.Caused by Bad Auxiliary Switch on K1 Relay.Auxiliary Switch Replaced

ML19339A721
Person / Time
Site:	Sequoyah
Issue date:	10/24/1980
From:	Romine W TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19339A720	List: 05000327/LER-1980-166, Forwards LER 80-166/03L-0 05000327/LER-1980-166-03, /03L-0:on 800927,during Normal Operation in Mode 4,output Breaker for Vital Inverter 2-IV Tripped Rendering Vital Instrument Power Board 2-IV Inoperable.Caused by Bad Auxiliary Switch on K1 Relay.Auxiliary Switch Replaced
References
LER-80-166-03L, LER-80-166-3L, NUDOCS 8011040575
Download: ML19339A721 (2)

LER-1980-166, /03L-0:on 800927,during Normal Operation in Mode 4,output Breaker for Vital Inverter 2-IV Tripped Rendering Vital Instrument Power Board 2-IV Inoperable.Caused by Bad Auxiliary Switch on K1 Relay.Auxiliary Switch Replaced

Event date:
Report date:
3271980166R03 - NRC Website

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60 6t DOCKET NuYOEM 68 69 EVENT DATE 74 FP ptPCRT DAf t 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h Lo_L2_J l Ouring normal operation in mode 4. the outeut breaker for vital invereer

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lo t Al l found tripped on 2 different occastnna The system was declared inoperable ehtm en t erl-foTs l I ing the action statement of LCO 3.8.2.1 on each occurrence. There was no effect on 1

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Sequoyah Nuclear Plant LER SUPPLEMENTAL INFORMATION t

f SQRO-50-327/80166 Technical Specification Involved 3.8.2.1 Reported Under Technical Specification 6.9.1.13.b Date of occurrence: 9/27/80 Time of occurrences: 2040 CDST 10/01/80 1730 CDST Identification and Description of Occurrence:

1.

On 9/27/80 at 2040 CDST during normal operation in mode 4, the output breaker for vital inverter 2-IV tripped rendering the vital instrument power board 2-IV inoperable and the action statement of LCO 3.8.2.1 was entered.

The output breaker was reset and tripped again. Initial investigation by maintenance was unable to determine the cause for the trip. A brush recorder was attached to the inverter and the output breaker was closed.

The inverter was declared operable at 1300 CDST on 9/28/80.

2.

On 10/1/80 at 1730 CDST during normal operation in mode 2, the output breaker for vital inverter 2-IV tripped rendering the vital instrument power board 2-IV inoperable and the action statement for LCO 3.6.2.1 was entered.

The brush recorder, installed on 9/28/80, indicated a trip frem the D. C. link circuit. Further investigation revealed a faulty auxiliary switch on the K1 relay.

Conditions Prior to Occurrences:

1.

Mode 4, 0% power 2.

Mode 2,3 1/2 % power Anparent - Cause of Occurrences:

Faulty Auxiliary Switch on the K1 Relay

Corrective Action

The auxiliary switch on the K1 relay was replaced and the 120 volt vital instrument power board 2-IV was declared operable at 2144 CDST on 10/1/80.

There have been no further trips since the switch was replaced.

Failure Data:

None