05000206/LER-1982-008, Forwards LER 82-008/03L-0.Detailed Event Analysis Submitted

Forwards LER 82-008/03L-0.Detailed Event Analysis Submitted

ML20050B709
Person / Time
Site:	San Onofre
Issue date:	03/29/1982
From:	Ray H SOUTHERN CALIFORNIA EDISON CO.
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20050B710	List: 05000206/LER-1982-008, Forwards LER 82-008/03L-0.Detailed Event Analysis Submitted 05000206/LER-1982-008-03, /03L-0:on 820227,during Performance of Special Engineering Safety Injection Test,Safeguard Load Sequencer Failed to Activate X Subchannel Sys Relays.Caused by Power Transistor Failure.Circuit Card Replaced
References
NUDOCS 8204070271
Download: ML20050B709 (2)

LER-1982-008, Forwards LER 82-008/03L-0.Detailed Event Analysis Submitted

Event date:
Report date:
2061982008R00 - NRC Website

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U. S. Nuclear Regulatory Commission g

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Region V 2

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9 Mr. R. H. Engelken, Regional Administrato

1. .s Attention:

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DOCKET N0. 50-20 Licensee Event Report No.82-008 San Onofre Nuclear Generating Station, Unit 1

Dear Sir:

This letter describes a reportable occurrence involving the operability of the Safeguard Load Sequencing System (SLSS). Submittal is in accordance with the requirements stipulated in Section 6.9.2.b of Appendix A to the Pro-visional Operating License DPR-13.

On February 27, 1982, the plant was in the process of being shut down and was in hot standby. A special engineering test required per Technical Spect-fication section 4.2.3 was in progress on the Safety Injection System when several of the containment isolation valves failed to close and breakers i

supplying the condensate and heater drain pumps failed to open and strip these loads.

Subsequent investigation revealed that the mis-operation of the com-l ponents and valves was caused by the lack of outputs from the Number 1 SLSS l

Unit. The X sub-channel of this sequencer was tested and shown to be non-operational. The cause of the system failure was traced to a power transistor in one of four identical relay driver circuits on a circuit board. This printed circuit board was replaced and the No.1 SLSS successfully tested February 28. This is the first failure of an output stage transistor in five years of operation. Thus, we do not believe this failure is a generic concern at this time.

The Number 2 SLSS operated properly during this test and successfully actuated its train-related components. As a result, there was no loss of any protective function during this occurrence, including containment isolation.$$

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The Number 1 SLSS had been successfully tested on February 2,1982.

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J Therefore, the Number 1 SLSS could not have been inoperable for more than

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three and one-half weeks.

f204070271 82032 gDRADOCK 05000206 PDR

Mr. R. H. Engelken March 29,1982 A review of the diesel generator's capacity was performed to evaluate the effect of the additional load due to the failure of the sequencer to strip the non-safety related loads. The diesel generator has a design load capacity of 6000 KW. The total additional load would have been 1500 KW. Thus, the diesel could have been loaded with as much as 4650 KW as a consequence of this failure of the automatic sequencer leaving a safety margin of 1350 KW.

There was no release of radiation and no impact on public health and safety associated with this event.

Should you require additional information, please contact me.

Sincerely, itBr%lqtung

Enclosure:

Licensee Event Report. LER No.82-008 cc:

U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Office of Management Information & Program Control Institute of Nuclear Power Operations (INP0)

L. F. Miller (USNRC Resident Inspector) f e

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