05000369/LER-1981-091, Forwards LER 81-091/03L-0.Detailed Event Analysis Encl

Forwards LER 81-091/03L-0.Detailed Event Analysis Encl

ML20009G037
Person / Time
Site:	McGuire
Issue date:	06/25/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009G038	List: 05000369/LER-1981-091, Forwards LER 81-091/03L-0.Detailed Event Analysis Encl 05000369/LER-1981-091-03, /03L-0:on 810530,peak Shock Annuciator Amber Light Observed On.Caused by Light Reed Switch from Triaxial response-spectrum Recorder Making Contact.Reed Switch Adjusted,Tested & Delared Operable
References
NUDOCS 8108030270
Download: ML20009G037 (3)

LER-1981-091, Forwards LER 81-091/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691981091R00 - NRC Website

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June 25, 1981 Mr. J. P. O'Reilly, Director U. S. Nuclear Regulatory Connaission k :g Q N'/,N Region II

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Re: McGuire Nuclear Station Unit 1 Ci jUL 3 1]ggj >

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Dear Mr. O'Reilly:

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Co to Please find attached Reportable Occurrence Report R0-369 81=

This report concerns TA 3.3.3.3; "the seismic monitoring instrumentation shown in Table 3.3-7 shall be operable." This incident was considered to be of no significance with respect to the health and safety of the public.

Ve truly yours, U-(b, n

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4114== 0. Parker, Jr.

PBN/php Attachment cc: Director Mr. Bill Lavalee Office of Management and Program Analysis Nuclear Safety Analysis Center U. S. Nuclear Regulatory Commission P. O. Box 10412 Washington, D. C.

20555 Palo Alto, California 94303 l

Ms. M. J. Graham Resident Inspector-NRC McGuire Nuclear Station

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4 McGUIRE NUCLEAR STATION INCIDENT REPORT LER/RO REPORT NUMBER:

81-091/03L-0 REPORT DATE; June 25, 1981 OCCURRENCE DATE: May 30, 1981 LICENSEE: Duke Power Company FACILITY: McGuire Unit 1, Cornelius, NC DOCKET NO.: 05000369 IDr.nnriCATION OF OCCURRENCE: A Tr4 =v4 =1 Response-Spectrum Recorder was declared inoperable.

CONDITION OF OCCURRENCEr Mode 4, Hot Shutdown DESCRIPTION OF OCCURRENCE: The "16 Hz" amber light on the Peak Shock Annunciator in the Control Room had been ON since May 24, 1981. A work request was initiated to troubleshoot the failed equipment. Since Control Room personnel vert. not sure where the signal was coming from, the equipment was not declared inoperable until May 30, 1981. This was a reportable incident pursuant to Technical Specification 3.3.3.3.

APPARENT CAUSE OF OCCURRENCE: The "16 Hz" amber light of the Peak Shock Annunciator was actuated because its reed switch from the Triaxial Response-Spectrum Recorder made contact.

l ANALYSIS OF' OCCURRENCE: The Peak Shock Annunciator (Model PSA-1575, Engdahl Enterprises) in the Control Room.provides instantaneous visual indications when predetermined acceleration limits (2-25 Hz shock spectrum) have been exceeded.

j This equipment receives iPs input signal from cae of the three Tr4=v4=1 Response-Spectrum Recordezaprovided in the plant for seismic monitoring. The appropriate Peak Shock Recorder, (Model PSR 1200-H/V012A, Engdahl Enterprises) is located on the Containment Base Slab. Each recorder (tria=ial) is provided with 12 reeds of different lengths and weights (one for each frequency),11 of which have dual switch contacts.

A_ switch is closed whenever its reed travels a predetermined distance. This in turn causes its respective amber light on the Peak Shock Annunciator to come ON when the design limit (normally 70%) is approached. The red light also comes ON when the design limit is exceeded.

On May 24, 1981, the horizontal (North-South) "16 Hz" amber light came ON but it was not declared inoperable until May 30, 1981 because Control Room personnel did not know that the equipment was part of the Triaxial Response-Sp2ctrum Recorder. A work request was initiated to troubleshoot the equipment and per-sonnel found that the associated switch of the no.10 reed in the recorder was making contact. The switch was readjusted to open and the instrument was tes':ed for proper operation per instrument procedure, " Peak Shock Recorder and Annunciator Calibration." The instrument was calibrated and declared operable on June 3, 1981 at 1027 hours0.0119 days <br />0.285 hours <br />0.0017 weeks <br />3.907735e-4 months <br />.

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LER/RO REPORT NUMBER 81-092/03L-0 Page 2

SAFETY ANALYSIS

Although the failed equipment was not declared inoperable until af ter 7 days, the Action Statement in the Technical Specification 3.3.3.3 was not violated because the equipment was restored to operable status within the 30 day period. No seismic event occurred while the recorder and its Peak Shock. Annunciator were inoperable. Had there been an event during that time, this Triarial Response-Spectrum Recorder would have still recorded the static accelerations, including the "16 Hz" shock spectrum, on their appropriate reeds.

Earthquake data would have also been gathered and analyzed by several independent ceismic monitoring instruments provided in the plant. Hence, the safe operation of the plant and the health and safety of the public were not affected by this incident. In the event of an earthquake during normal operation, the plant is chut down if the recorded seismic data exceeds the Operating Basic Earthquake.

The plant's structures, systems, and equipment are then thoroughly investigated.

CORRECTIVE ACTION

A work r'equest was initiated to troubleshoot the failed instrument. The. setting of the no.10 reed switch contact was adjusted and tested for proper operation. The Peak Shock Annunciator was declared cperable on June 3, 1981 at 1027 hours0.0119 days <br />0.285 hours <br />0.0017 weeks <br />3.907735e-4 months <br />.

Control Room personnel will be instructed to improve their knowledge on.this instrument sa well as the other seismic monitoring equipment. This will enable them to respond more appropriately to this type of incident in the future.

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