05000369/LER-1981-102, Forwards LER 81-102/03L-0.Detailed Event Analysis Encl

Forwards LER 81-102/03L-0.Detailed Event Analysis Encl

ML20009F441
Person / Time
Site:	McGuire
Issue date:	07/21/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009F442	List: 05000369/LER-1981-102, Forwards LER 81-102/03L-0.Detailed Event Analysis Encl 05000369/LER-1981-102-03, /03L-0:on 810621,peak Shock Annunciation 20.2 Hz Red Light Was Actuated.Caused by Wire from Contact Switch in Triaxial response-spectrum Recorder Pinched Between Contact Block & Mounting Frame,Resulting in Short.Wire Cleared
References
NUDOCS 8107310157
Download: ML20009F441 (3)

LER-1981-102, Forwards LER 81-102/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691981102R00 - NRC Website

text

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DUKE POWER COMPANY LON/JCy Powen DUILDtwo 422 SouTu Ctr racu SrazzT, CnAnz.oTTz, N. C. as242

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VeC F P8ESaotNT TELEp=ON E ASEA 704 27 3..o e s src. aaoove*>ow July 21, 1981 Mr. James P. O'Reilly, Director U. S. Nuclear Regulatory Commission 8,\\\\

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101 Marietta Street, Suite 3100

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Atlanta, Georgia 30303 S

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JUL.9 01981 - [-

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McGuire Nuclear Station Unit 1 f. %

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Docket No. 50-369 mince.

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Dear Mr.-O'Reilly:

L sr sp Please find attached Reportable Occurrence Report R0-369/ -

This report concerns Tech;.ical Specification 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 signi icance with respect to the health and safety of the public.

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Ve y truly yours,

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[ / William O. Parker, Jr.

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Attachment cc:

Director Mr. Bill 1.avallee Office of Management and Program Analysis Nuclear Safety Analysis Center U. S. Nuclear Regulatory Commission Post Office Box 10412 Washington, D. C.

20555 Palo Alto, CA 94303 Ms. M. J. Graham Resident Inspector - NRC McGuire Nuclear Station 0

9107310157 810721 PDR ADOCK 05000369 S

PDR

r McGUIRE NUCLEAR STATION REPORTABLE OCCURRENCE Report Numbe_r:

81-102 Report Date:

July 21, 1981 Occurrence Date:

June 21, 1981 Facility: McGuiro Unit 1, F.ornellus, N. C.

Identification of Occurrence:

The Triaxial Response-Spectrum Recorder for the containment base slab was declared inoperable.

Condition Prior to Occurrence:

Mode 5, Cold Shutdown Description of Occurrence:

On June 21, 1981 at 0450 hours0.00521 days <br />0.125 hours <br />7.440476e-4 weeks <br />1.71225e-4 months <br />, the Shift Supervisor noticed that the Peak Shock Annunciator in the Control Room was actuated.

The "20.2 Hz" red light for the horizontal shock in the East-West direction was ON.

Control Room personnel tried to reset the equipment but it would not' reset and it was, therefore, declared inoperable.

This was a reportable incident pursuant to Technical Speci.fication 3.3.3.3.

App'arent Cause of Occurrence: The "20.2 Hz" red light of the Peak Shock Annunci-ator was actuated because a wire from.its contact switch in the Triaxial Response-l Spectrum Recorder was shorted to ground.

Analysis of Occurrence: The Peak Shock Annunciator (Model PSA-1575, Engdahl Enterprises) in the Control Room provides instantaneous visual indication when predetermined acceleration limits (2-25 Hz shock spectrum) have been exceeded.

i This equipment receives its input signal from one of the Triaxial Response-Spectrum Recorders provided in tbe plant for seismic monitoring.

The Peak Shock

- Recorder (Model PSR 1200-H/V012A, Engdahl Enterprises) is located on the Con-tainment Base Stab.

Each recorder (triaxial) is provided with 12 reeds of different lengths and weights (one for each frequency), 11 of which have dual switch contacts.

A switch closes whenever its reed travels a predetermined dis-4 cance.

This causes its respective amber light on the Peak Shock Annunciator to come ON when the design limit (norma ~ly 70%) is approached.

The red light also comes ON when the design limit is exceeded.

Un June 21, 1981 at-0450 hours, the Shift Supervisor noticed that the Peak Shock l

Annunciator's horizontal (East-West) "20.2 Hz" red light was ON.

This equipment was declared inoperable because it would not reset.

A work request was initiated to troubleshoot the failed instrument.

The Peak Shocc Recorder was found to be 4

j sending a false signal because the wire that connects the contact switch to a printed circuit board inside the recorder was shorted to ground.

It was pinched r

between the contact block (where the contacts are mounted) and the metal frame where the contact block is mounted. The pinched wire may have occurred during the last calibration checkout, June 8, 1981, since it required removing, and then replacing, all the recorder's reeds.

The block was lifted and the pinched' wire cleared.

The Peak Shock Annunciator was reset and the "20.2 Hz" red light went 0FF.

The equipment was checked for proper operation and it was declared operable

- on June 22, 1981 at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />.

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Safety Analysis

No seismic event occurred while the recorder and its Peak Shock Annunciator were inoperable.

Had there been an event during that time, this Triaxial Response-S;actrum Recorder would have still recorded the static accelerations, including the "20.2 Hz" shock spectrum, on their appropriate reeds.

Earthquake data would have also been gathered and analyzed by several independent seismic 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.

Corrective Action

A work request was initiated to troubleshoot the failed instrument.

The pinched wire was cleared which corrected the wire to ground

,short.

The Peak Shock Annunciator was reset and the equipm,ent was checked and 3LA(

'de:..ared operational.

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