05000272/LER-1979-077-03, /03L-0:on 791224,during Startup,Breaker 11ASD tripped,de-energizing 4 Kv Vital Bus 1A & Supplied Plant Loads.Caused by Failure of Components in Logic Circuit.Five Logic Boards & One Relay Replaced

/03L-0:on 791224,during Startup,Breaker 11ASD tripped,de-energizing 4 Kv Vital Bus 1A & Supplied Plant Loads.Caused by Failure of Components in Logic Circuit.Five Logic Boards & One Relay Replaced

ML18081A971
Person / Time
Site:	Salem
Issue date:	01/23/1980
From:	Kapple A Public Service Enterprise Group
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML18081A970	List: 05000272/LER-1979-077-03, /03L-0:on 791224,during Startup,Breaker 11ASD tripped,de-energizing 4 Kv Vital Bus 1A & Supplied Plant Loads.Caused by Failure of Components in Logic Circuit.Five Logic Boards & One Relay Replaced
References
LER-79-077-03L, LER-79-77-3L, NUDOCS 8001290337
Download: ML18081A971 (3)

LER-1979-077, /03L-0:on 791224,during Startup,Breaker 11ASD tripped,de-energizing 4 Kv Vital Bus 1A & Supplied Plant Loads.Caused by Failure of Components in Logic Circuit.Five Logic Boards & One Relay Replaced

Event date:
Report date:
2721979077R03 - NRC Website

text

Report Number:

79-77/03L Report Date:

1/23/80 Occurrence Date:

12/24/79 Facility:

Salem Generating Station Public Service Electric & Gas Company Hancock's Bridge, New Jersey 08038 IDENTIFICATION OF OCCURRENCE:

lA Safeguard Equipment Control (SEC) Inoperable CONDITIONS PRIOR TO OCCURRENCE:

Operational Mode 3 DESCRIPTION OF OCCURRENCE:

At 1004 hours0.0116 days <br />0.279 hours <br />0.00166 weeks <br />3.82022e-4 months <br />, the llASD infeed breaker to the lA 4kV vital bus tripped, de-energizing the bus and causing loss of various plant equipment.

The lA emergency diesel generator started but did not go through the loading sequence.

The control room operator initiated recovery of de-energized equipment and an equipment operator went to the relay room to investigate and reset the lA SEC panel.

Indicated trouble was bus undervoltage and underfrequency brit the operator had no difficulty resetting the panel.

At 1008 hours0.0117 days <br />0.28 hours <br />0.00167 weeks <br />3.83544e-4 months <br />, the llASD breaker was reclosed and the lA emergency diesel was secured.

Recovery from loss of de-energized equipment was complete by 1013 hours0.0117 days <br />0.281 hours <br />0.00167 weeks <br />3.854465e-4 months <br />.

Maintenance electricians investigated the occurrence; and at 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br />, declared the lA SEC inoperable.

Technical Specifications 3.8.1.1 and 3.3.2.1 Action Statements were implemented.

At 2020 hours0.0234 days <br />0.561 hours <br />0.00334 weeks <br />7.6861e-4 months <br />, the lA SEC was returned to service and the Action Statements were terminated.

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE:

The cause of this occurrence was a failure in the lA SEC logic circuitry which incorrectly monitored an undervoltage condition on the lA vital bus and tripped the llASD infeed breaker.

The SEC operated as designed by unloading the bus and starting the emergency diesel generator and not initiating the auto load sequence which requires a fault on two of the three vital busses.

ANALYSIS OF OCCURRENCE:

Technical Specification 3.3.2.1 requires that with the number of operable SEC channels one less than the total number of channels, be in Hot Standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

The reactor was in Hot Standby throughout this occurrence.

The lA SEC channel was repaired and returned to service in 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> 16 minutes.

8001290 ~~

tER 79-77/03L Technical Specification 3.8.1.1 requires that with a diesel generator inoperable, remaining AC sources shall be demonstrated operable by performing 4.8.1.1.la and 4.8.l.l.2a2 surveillances within one hour and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter.

This Technical Specification was implemented and the surveillances performed as required although the offsite-onsite transmission distribution systems and the diesel generators were operable throughout this occurrence.

CORRECTIVE ACTION

The entire logic drawer was replaced with a spare unit and tested satisfactorily before returning the lA SEC to service.

Trouble-shooting of the failed drawer resulted in five logic boards and one faulty relay in the relay stack being replaced.

FAILURE DATA:

Safeguards Equipment Control System Automation Industries, Inc.

Silver Springs, Maryland Prepared By A. W. Kapple Manager -

Salem Generating Station SORC Meeting No.

05-80

17*711,.

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LICENSEE EVENT REPORT

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(())] I During startup operations, the llASD breaker tripped, de-energizing the lA 4kV

((II) I vital bus and supplied plant loads.

The lA SEC panel was reset and the llASD breaker was reclosed.

Maintenance electricians declared the lA SEC inoperable and Action Statements for T/S 3.8.1.l and 3.3.2.1 were implemented.

The lA *SEC was repaired, tested and returned to service in 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> and 16 minutes.

The plant was!

C£:I:I:J I in Hot Standby th~oughout this occurrence.

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Failed components in the logic circuit sensed an erroneous undervoltage condition on lA vital bus and opened the llASD infeed breaker.

The entire logic drawer was replaced to expedite recovery of the lA SEC.

Further troubleshooting of the IJ:II] I failed drawer resulted in five logic boards and one relay beinq replaced.

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