ENS 41468
ENS Event | |
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10:54 Mar 8, 2005 | |
Title | Rhr Pump Tripped Due to Loss of Valve Position Indication |
Event Description | The following information was provided by the licensee (licensee text in quotes)
During isolation of the 'A' Safety Relief Valve, the 12 Residual Heat Removal (RHR) Pump tripped while in service for shutdown cooling. The isolation and shutdown cooling were subsequently restored such that shutdown cooling was lost for approximately 13 minutes. Several Control Room alarms were received at approximately 0454 [CST] while the isolation was being hung. The Control Room Supervisor investigated the alarms and the Reactor Operator identified that the 12 RHR Pump had tripped. The isolation was lifted and shutdown cooling was restored at approximately 0507 [CST]. Operators observed that reactor water temperature and level remained stable at 99 degrees F and 651 inches (above the bottom of the vessel), respectively, during the event. The isolation being hung apparently caused a loss of position indication for the RHR pump inlet valve. With no position indication, the pump logic sensed a loss of suction flow path, which caused the RHR pump to trip. The event is under investigation. The NRC resident has been notified. |
Where | |
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Monticello ![]() Minnesota (NRC Region 3) | |
Reporting | |
10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
Time - Person (Reporting Time:+0.78 h0.0325 days <br />0.00464 weeks <br />0.00107 months <br />) | |
Opened: | Randy Sand 11:41 Mar 8, 2005 |
NRC Officer: | Bill Gott |
Last Updated: | Mar 8, 2005 |
41468 - NRC Website
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Unit 1 | |
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Reactor critical | Not Critical |
Scram | No |
Before | Cold Shutdown (0 %) |
After | Cold Shutdown (0 %) |