ML19323H314

LER 80-044/03L-0:on 800510,control Power Fuses for Containment Particulate & Gas Radiation Monitors Blew When Restarting Sample Pump.Possibly Caused by Current Feedback from Motor Contactor

ML19323H314
Person / Time
Site:	North Anna
Issue date:	06/09/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19323H310	List: ML19323H309 ML19323H314
References
LER-80-044-03L, LER-80-44-3L, NUDOCS 8006120362
Download: ML19323H314 (2)

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t l o t a l brole numo for RM-FMS-159 af ter charcoal filter replacement. Since the  !

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Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 1 Docket No. 50-338 Report No. 80-044/03L-0 Description of Event On May 10, 1980, with the unit at 100 percent power, control power fuses for the containment particulate and gas radiation monitors blew when restarting sample pump of RM-RMS-159 after charcoal filter replacement.

This resulted in loss of sample flow from the containment atmosphere to the containment gas and particulate monitors.

Probable Consequences of Occurrence The containment particulate and gas radiation monitoring systems are used as a primary means of detecting a Reactor Coolant System leak. The time that the system was out of commission was on the order of five minutes, which was the time necessary to replace the fuse. The effects of this event was also minimized because the containment sump discharge flow measurement system was in operation at the time and the containment air purge and exhaust system was closed and no escape of air from the containment could occur. As a result, the health and safety of the general public were not affected by this event.

Cause of Occurrance The exact cause for the fuses blowing is unknown at this time. It is suspected that the reason for the fuses blowing is due to possible current feedback from the motor contactor. However, there is question at this time as to the proper type of fuse necessary to prevent spurious failure of the fuse and also protect the radiation monitoring equipment. The control circuits for five other radiation monitors are protected by the same fuse.

Immediate Corrective Action A new power fuse was immediately installed and both radiation monitors were then returned to service.

Scheduled Corrective Action An Engineering study will be performed to determine the cause of the ,

failure of this fuse. There is a question as to the correct fuse required 1 as well as to determine whether an electrical overload exists due to l fusing additional equipment.

Actions Taken to Prevent Recurrance No further actions are required.

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