05000369/LER-1981-062, Forwards LER 81-062/03L-0.Detailed Event Analysis Encl

Forwards LER 81-062/03L-0.Detailed Event Analysis Encl

ML20005A016
Person / Time
Site:	McGuire
Issue date:	05/21/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20005A017	List: 05000369/LER-1981-062, Forwards LER 81-062/03L-0.Detailed Event Analysis Encl 05000369/LER-1981-062-03, /03L-0:on 810421,while in Mode 3,Channel 4 of Steam Generator 1D Narrow Range Level Indicator Failed High. Caused by Loose Plug on Bellow Housing & Condensed Steam Draining from Impulse Line.Plug Tightened
References
NUDOCS 8106290250
Download: ML20005A016 (3)

LER-1981-062, Forwards LER 81-062/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691981062R00 - NRC Website

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May 21, 1981 Mr. James P. O'Reilly, Director U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 Re: McGuire Nuclear Station Unit i Docket No. 50-369

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-369/81-62.

This report concerns Channel 4 of the S/G 1D Narrow Range Level Instrumentation being de-clared inoperable. This incident was considered to be of no significance with respect to the health and safety of the public.

Very truly yours, L

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'41111am O. Parker, Jr.

R'40: pw Attachment cc: Director Mr. Bill Lavallee Office of Management & Program Analysis Nuclear Safety Analysis Center U.S. Nuclear Regulatory Commission Post Offica Bcx 10412

'4ashington, D. C.

20555 Palo Alto, California 94303 Ms. M. J. Graham Resident Inspector - SIC McGuire Nuclear Station

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, c McGUIRE NUCLEAR STATION INCIDENT REPORT Report Number:

81-62

' Report'Date: May 12, 1981-Occurrence Date: April-21, 1981

. Facility: McGuire Unit 1, Cornelius, N. C.

' Identification of Occurrence: ' Channel 4 of Steam Generator (S/G) 1D Narrow Range Level Instrumentation was declared inoperable.

s Condition Prior to Occurrence: Mode 3, Hot Standby Description'of Occurrence: On April 21, 1981 at 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br />, Channel 4 S/G 1D Narrow Range Level Indicator failed high.

The appropriate annunciator alarm

.and status light indications were also actuated. The Shift Supervisor declared that channe1' inoperable and was therefore reportable pursuant to Technical 4

Specification 3.3.2.

Apparent Cause of Occurrence: The Channel 4 Narrow Range Level Instrumentation

.for S/G ID.became inoperable because the appropriate level trans=itter developed a leak.

The plug on one of the bellows' housing was loose which caused the liquid on its reference leg-(impulse line) to drain out.

Analysis of Occurrence: On the morning of April 21, 1981, the S/G ID Narrow

. Range Level' indicators in the Control Room were reading about 25% when an annunciator alarm, "S/G D LEVEL DEVIATION" was actuated.

The Control Room

. operators found that the Channel 4 indicator had failed high. A work request was immediately initiated to troubleshoot and provide any necessary repair on the failed instrument. The affected channel was also placed in the TRIP position.

It was found that the plug on one of'the bellows' housing was loose and the liquid (condensed steam) on its i= pulse line had drained. The trans-mitter was valved out and the loose plug was tightened.

Since this channel had just been recently calibrated under the Preventive Maintenance Program, the transmitter was valved back in and the condensing pot (which condenses steam) filled the drained impulse line. Af ter it was checked that there were no more leaks, the affected channel was removed from the TRIP position, the annunciator alarm had cleared and its receiver gauge was indicating properly.

t This channel was declared operable on April 21, 1981 at 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br />.

Safety Analysis

When Channel 4 of S/G ID Narrow Range Level Instrumentation failed, the other two separate and independent channels were operable; hence, the S/G ID level was being continously. monitored. The transmitter's per-

' missive interlock signal was simulated by placing the channel in the TRIP posi, tion. Therefore, its control' logic to trip the turbine and isolate

feedwater was still. functioning.

If the unit had been at normal power, operation would have continued until the next required functional testing of Channel 4 provided this channel is placed in the tripped position within one hour..The plant's safe operation and the health and safety of the public were not affected by this incident.

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e-Report Number 81-62 Page'2.

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Corrective Action: Channel 4 of S/G ID Narrow Range Level Instrumentation was immediately placed in the TRIP condition when it failed. A work request was

- initiated to prsvide corrective maintenance. The loose plug which had caused the instrument' failure was tightened. The affected channel was checked out-for proper operation and declared operable on April 21, 1981 at 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br />.

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