05000369/LER-1981-182, Forwards LER 81-182/03L-0.Detailed Event Analysis Encl

Forwards LER 81-182/03L-0.Detailed Event Analysis Encl

ML20039C438
Person / Time
Site:	McGuire
Issue date:	12/16/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20039C439	List: 05000369/LER-1981-182, Forwards LER 81-182/03L-0.Detailed Event Analysis Encl 05000369/LER-1981-182-03, /03L-0:on 811116,source Range Channel N-31 High Voltage Power Supply Failed.Caused by Overheating of Component Transformer.Power Supply Replaced & Aligned
References
NUDOCS 8112290350
Download: ML20039C438 (2)

LER-1981-182, Forwards LER 81-182/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691981182R00 - NRC Website

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December 16' 1981 Vice Pats >0t%T Ttt t p=ow t:Aata 704 STCame PACOuctio*e 373-4083 Mr. J. P. O'Reilly, Director U. S. Nuclear Regulatory Commission g 8' B

Region 11 cP 101 Marietta Street, Suite 3100

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Please find attached Reportable Occurrence Report R0-369/81-182. This report concerns T.S.3.3.1, "As a minimum, the reactor trip system instrumentation channels and interlocks of Table 3.3-1 shall be operable...".

This incident was considered to be of no significance with respect to the health and safety of the public.

Verytrulyyours,]

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PBN/jfw Attachmert cc: Director Records Center Office of Management and Program Analysis Institute of Nuclear Power Operations U. S. Nuclear Regulatory Commission 1820 Water Place Washington, D. C.

20555 Atlanta, Georgia 30339 Mr. P. R. Bemis Senior Resident Inspector-NRC McGuire Nuclear Station

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4 DUKE POWER COMPANY McGUIRE NUCLEAR STATION REPORTABLE OCCURRENCE REPORT NO.81-181 REPORT DATE: December 16, 1981 FACILITY: McCuire Unit 1, Cornelius, NC IDENTIFICATION: Loss of One Channel of Source Range Nuclear Instrumentation Due to Failure of the High Voltage Power Supply

INTRODUCTION

On November 16, while Unit I was in mode 4, hot shutdown, enroute to cold shutdown for maintenance, technicians were conducting Source Range Nuclear Instrumentation Functional tests.

In the process of testing source range channel N-31, its high voltage power supply failed.

The failure of the source range channel in this instance was a degradation of plant status and reportable in accordance with Technical Specification 3.3.1.

The high voltage power supply was replaced and aligned in accordance with the pro-cedure, " Source Range High Voltage Power Supply NQ101 Alignment".

The source range channel was then functionally verified through performance of the " Nuclear Instru-mentation System Source Range Functional Test", and declared operable on November 17.

Inspection of the faulty power supply determined that a component transformer had overheated.

EVALUATION: The failure of the channel during functional verification was indica-tive of a possible personnel error in the conduct of the test.

Therefore, a " walk thru" of the procedure was conducted with the technicians who had performed the test.

Their methods were found not to be suspect and were in conformance with procedural requirements. As a result of this check, the timing of this failure is determined to be coincidental.

It was noted.that the transformer in the replacement power supply was ventilated, i.e., had a ventilated top cover plate.

The failed transformer had a closed top with heat sinks to remove heat from the transformer internals.

The model numbers of the associated power supplies are the same.

The units are 300/2500 VDC, 0-10ma adjustable power supplies; Model No. UFMD-X54/W/M1, manufactured by Power Designs, Incorporated.

CORRECTIVE ACTION

Replacement of the faulty power supply, and alignment of the source range channel were the only measures necessary to correct the condition.

VERIFICATION:

The channel has functioned correctly since the repair.

SAFETY ANALYSIS

During this incident the redundant source range nuclear instru-mentation channel was functional' The health and safety of the public were unaffected by this event.