05000369/LER-1981-087, Forwards LER 81-087/03L-0.Detailed Event Analysis Encl

Forwards LER 81-087/03L-0.Detailed Event Analysis Encl

ML20009C074
Person / Time
Site:	McGuire
Issue date:	06/17/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009C075	List: 05000369/LER-1981-087, Forwards LER 81-087/03L-0.Detailed Event Analysis Encl 05000369/LER-1981-087-03, /03L-0:on 810518,during Initial Fuel Loading,Flow Indicator of Gross Radioactivity Monitor (EMF-31) on Waste Water Treatment Line Was Found Not Functioning.Caused by Clogged Flow Switch & Strainer.Monitor Cleaned
References
NUDOCS 8107200242
Download: ML20009C074 (2)

LER-1981-087, Forwards LER 81-087/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691981087R00 - NRC Website

text

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Mr. James P. O'Reilly, Director.

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Re: McGuire Nuclear Station Unit 1 h/g i Docket No. 50-369 Q

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Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report RO-369/81-87. This report concerns the gross radioactivity monitor on the Conventional Waste Water Treatment Line (EMF-31) being inoperable. This incident was considered to be of significance with respect to the health and safety of the public.

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' William O. Parker, Jr. /

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pw Attachment cc: Director Mr. Bill Lavallee Office of Management & Program Analysis Nuclear Safety Analysis Center U. S. Nuclear Regulatory Commission P. O. Box 10412 Washington, D. C.

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

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McGUIRE NUCLEAR STATION INCIDENT REPORT Report Number: 81-87 Report Date: June 17, 1981 Occurrence Date: May 18, 1981 Iacility: ~McGuire Unit 1, Cornelius, N. C.

Identification of Occurrence: The gross radioactivity monitor, EMF-31, on the conventional waste water (WC) treatment line was declared inoperable.

Conditions Prior to Occurrence: Mode 5, cold shutdown. Prior to initial criticality.

Description of Occurrence: Bits of trash had clogged the flow switch for the EMF-31 sample line. This resulted la the monitor failing in the full flow con-dition. The associated strainer, upstream of the flow switch, had also clogged due to trash. This shut off sample flow to the monitor, thus rendering it in-operabic.. This was reportable pursuant to Technical Specification 3.3.3.8 and required bnplamentation of Action Statement #29 of Table 3.3-12.

Failure of this monitor wss not immediately detected due to the clogged flow switch.

Apparent Cause: The sample tap for EHF-31 extends from the bottom of the WC discharge line. bediment, present in the liquid discharge, accumulated in the flow switch and in the strainer to a suf ficie : degree to clog them both and tender the monitor inoperable.

Analysis of Occurrence:

On May 18, about 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br />, an engineer noticed that the flow indicator of EMF-31 was not functioning. The Shift Supervisor de-clared the system inoperable and notified H.P. to repair the monitor.

A technician examined the monitor and the problem was found to be caused by bits of solid trash in the flow switch and in the sample line. He cleaned out the flow switch, strainer, and sample line with compressed air and returned the system to operation. The system was declared operable at 1920 hours0.0222 days <br />0.533 hours <br />0.00317 weeks <br />7.3056e-4 months <br /> of that same day.

Safety Analysis

The function of EMF-31 is to monitor radioactivity present in liquid effluents which exit the plant via the WC discharge line. The presence of only new, non-irradiated fuel on site and weekly results of the analyses which are performed on this system confirmed that neither the health and safety of the public nor the safe operation of the plant were affected by this in-cident.

Corrective Action

H.P. initiated a work request to have the system repaired and returned to service. The sample tap will be reoriented 90 on the WC discharge line to minimize the potential of sediment restricting the flow and operation of the EMF. Additionally, this system will be checked out and cleaned on a weekly basis.