05000254/LER-1980-009-03, /03L-0:on 800410,while Performing Motor Operated Valve Operability Test,Thermal Overload Relay for B-loop Suppression Chamber Cooling Valve Tripped.Caused by High Motor Starting Currents.Torque Switch Adjusted

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/03L-0:on 800410,while Performing Motor Operated Valve Operability Test,Thermal Overload Relay for B-loop Suppression Chamber Cooling Valve Tripped.Caused by High Motor Starting Currents.Torque Switch Adjusted
ML19309H666
Person / Time
Site: Quad Cities 
Issue date: 04/30/1980
From: Eagle J
COMMONWEALTH EDISON CO.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19309H664 List:
References
LER-80-009-03L-04, LER-80-9-3L-4, NUDOCS 8005130634
Download: ML19309H666 (2)


LER-1980-009, /03L-0:on 800410,while Performing Motor Operated Valve Operability Test,Thermal Overload Relay for B-loop Suppression Chamber Cooling Valve Tripped.Caused by High Motor Starting Currents.Torque Switch Adjusted
Event date:
Report date:
2541980009R03 - NRC Website

text

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8 60 61 DOCK ET NUMBER 68 69 EV ENT QATE 74 75 PEPCRT DATE 80 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h l"oT2 l l While performing the LPCI Motor Ooerated Valve Operability Test. procedure QOS 1000-31 1 o 131 l the thermal overload relay for the B-loop suppression chamber cooling valve, MO l ITTTIi 1001-368, tripped while attempting to open the valve. The test was performed to l

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LER NUMBER:

LER/R0 80-09/03L-0 ll.

LICENSEE NAME: Commonwealth Edison Company Quad-Cities Nuclear Power Station lli.

FACILITY NAME: Unit One IV.

DOCKET NUMBER: 050-254 V.

EVENT DESCRIPTION

On April 10, 1980, while performing the LPCI Motor Operated Valve Operability Test, procedure QOS 1000-3, the thermal overload relay for the B-loop suppression chamber cooling valve (MO-1-1001-36B) tripped while attempting to open the valve. The relay was reset and upon actuation. the thermal overload relay tripped again.

The relay was re-set a sect.id time, and when attempting to open the valve the third time, the v41ve functioned properly. On the same day, while performing the RHRS Pump Operability Test, procedure QOS 1000-2, the tFtrmal overload relay tripped when attempting to open the same valve.

~he relay was re-set and the valve functioned properly. Work Request q0-4581 was written to investigate and repair the problem.

Unit One was in the RUN mode at 787 MWe and 2355 MWt.

VI.

PROBABLE CONSEQUENCES OF THE OCCURRENCE The probable consequences of this occurrence were minimal. The valve failed in the closed position, which is the normal operating position.

The valve is used for testing the "B" RHR loop and for suppression chamber cooling. The valve could have been manually operated if needed. The "A" Containment Cooling loop was also available for use if needed.

Safe operation of the reactor was not affected as a result of this occurrence.

Vll. CAUSE The probable cause of the thermal overload relay trip is attributed to high motor starting currents caused by a torque switch setting which was too high.

The valve is a 14 inch globe valve manufactured by Crane Company. The motor operator is a SMB-3 type operator made by Limi torque.

Vill. CORRECTIVE ACTION The immediate corrective action was to reset the thermal overload relay and continue attempting to operate the valve from the control room. Later, the torque switch was adjusted down from a setting of 2-1/4 to 2.

The valve was then successfully stroked three times and declared operable.

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