ML20008E907

LER 81-005/03L-0:on 810202,power Supply to Both Excore Range Monitors Was Interrupted.Caused by Maint Personnel Cutting Off Power to Investigate Steam Generator Status Lights & lo-lo Level Alarms.Personnel Instructed

ML20008E907
Person / Time
Site:	McGuire
Issue date:	03/04/1981
From:	Ouellette R DUKE POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20008E890	List: ML20008E889 ML20008E907
References
LER-81-005-03L, LER-81-5-3L, NUDOCS 8103100494
Download: ML20008E907 (2)

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MCGUIRE NUCLEAR STATION ISCIDENT REPORT Report Number: 369/81-05 Report Date: February 11, 1981 Occurrence Date: February 2, 1981 Facility: McGuire Unit 1, Cornelius, North Carolina Identification of Occurrence: Both source range monitors (Excore Instrumentation) were inoperable for 30 seconds.

Conditions Prior to Occurrence: Initial Fuel Loading, Mode 6 Description of Occurrence:

On February 2, 1981 at 0802 hours0.00928 days <br />0.223 hours <br />0.00133 weeks <br />3.05161e-4 months <br />, the source range monitors' power supplies were interrupted causing the indicating lights associated with the monitors to go of f for approximately 30 seconds and then come back on. This happened while I&E personnel were perforning maintenance work on steam generators 10-10 level alarms. The 30 second power interruption of these monitors caused a degraded mode of operation and was therefore reportable pursuant to Technical Specification 3.9.2.

Anparent Cause of Occurrence:

ISE personnel were investigating why the status lights on the steam generator A, B, and C lo-lo level alarms were actuated. As a troubleshooting technique, they attempted to completely isolate all input sigrsls that might have actuated the status lights in the Control Room. Since these signals could be coming from either Train A or B, both ' INPUT ERROR IFHIBIT' switches on the Solid State Protective System (SSPS) panel were inadvertently placed in the ' INHIBIT' position causing power interruption to the source range monitors.

Analysis of Occurrence:

The 30 second power interruption on the source range monitors occurred while there was maintenance work going on at the fuel transfer tube; the air pump that runs the conveyor was being replaced. Since there was no fuel movement at the time the incident occurred, there was no significant effect as to the ,

safety and health of the public.

Corrective Action:

Power to the source range monitors were restored after 30 seconds of interrup-tion when I&E personnel placed the ' INPUT ERROR INHIBIT' switch back in the

' NORMAL' position. I&E personnel were instructed not to perform maintenance work on testing on both trains of the SSPS cabinets at the same time even in Mode 6.

IP/0/A/3010/05, SSPS Safeguard Test, prohibits testing of both trains at the same t ime .