05000336/LER-1980-029-03, /03L-0:on 800812,during Surveillance Test on 12 U diesel,125 Vdc Ground Alarm Received.Caused by Frayed Insulation on Wire in Bendix Connector Allowing Contact Between Bare Wire & Connector Shell.Wire Recovered

/03L-0:on 800812,during Surveillance Test on 12 U diesel,125 Vdc Ground Alarm Received.Caused by Frayed Insulation on Wire in Bendix Connector Allowing Contact Between Bare Wire & Connector Shell.Wire Recovered

ML19343A224
Person / Time
Site:	Millstone
Issue date:	09/08/1980
From:	Harris J NORTHEAST NUCLEAR ENERGY CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19343A219	List: 05000336/LER-1980-028-03, /03L-0:on 800811,at 100% Power,Control Element Assembly 41 Dropped from 180 to Zero Steps.Caused by Faulty Jumper Cable from Refuel Disconnect Panel to Reactor Head. Power Reduced & Assembly Realigned.Replacement Planned 05000336/LER-1980-029-03, /03L-0:on 800812,during Surveillance Test on 12 U diesel,125 Vdc Ground Alarm Received.Caused by Frayed Insulation on Wire in Bendix Connector Allowing Contact Between Bare Wire & Connector Shell.Wire Recovered 05000336/LER-1980-030-03, /03L-0:on 800812,during Routine Operation, Containment Air Temp Exceeded 120 F.Caused by Svc Water Temp Control Valve to Reactor Bldg Closed Cooling Water Heat Exchangers Being Set Too High.Valve Readjusted ML19343A218
References
LER-80-029-03L, LER-80-29-3L, NUDOCS 8009160464
Download: ML19343A224 (1)

LER-1980-029, /03L-0:on 800812,during Surveillance Test on 12 U diesel,125 Vdc Ground Alarm Received.Caused by Frayed Insulation on Wire in Bendix Connector Allowing Contact Between Bare Wire & Connector Shell.Wire Recovered

Event date:
Report date:
3361980029R03 - NRC Website

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60 61 CCCKET NUMB ER 68 63 EVENT OATE 74 75 REFCRT CATE 83 EVENT DESCRIPTION AND PROB AB'.E CONSEQUENCES h 1o 121 lWhile the 120 diesel was being run for surveillance testing, a 125 VDC (Bus 201A) ground]

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33 34 35 26 37 40 41 42 43 4A 47 CAUSE CESCRIPTION AND CCRRECTIVE ACTICNS l i l o l l The cause of the ground was frayed insulation on one wire in the Bendix connector wnichi It li j l connects the sceed sensor to the governor allowing a bare wire to contact the connectori li#2l l shell causing a short circuit.

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r BOSTON EDISON COMPANY PILGRIM NUCLEAR POWER STATION DOCKET No. 50-293 Attachment to LER 80-049/03L-0

Description

On August 10 and 11, 1980 SSW P208B tripped.

On August 11 and 17, 1980 SSW P208E tripped.

On each occasion the trips resulted from thermal overload of their respective breaker's B1533 and B1444.

I= mediate investigation revealed no cause for these trips.

A detailed analysis was initiated to ascertain the cause of the trips and recommend corrective action.

Cause & Corrective Action The analysis indicates that the major conditions contributing to these trips are:

1.

An improvement in the SSW inlet water flow due to maintenance performed during the refuel IV outage.

2.

A reduction in heat transfer capability of the THCCW system in non essential loops.

3.

The number of SSW pumps in operation.

4.

The inlet water level to the SSW pumps.

5.

The inlet water temperature to the SSW pumps.

It is believed at this time that simultaneous operation of four SSW pumps with specific inlet water levels shifted the dynamic operating characteristic of B & E SSW pumps and resulted in protective trips of their respective breaker.

Permanent corrective action is being contemplated ; meanwhile, inlet water temperature decrease has alleviated the problem.

Emergency mode of operation requires two pump operation and therefore the safety margin, in this mode has not been reduced.

Following the completion of the analysis and implementation of permanent corrective measures an update report will be issued.