ENS 44957
ENS Event | |
|---|---|
10:43 Apr 2, 2009 | |
| Title | |
| Event Description | At 0543 [CDT] on April 2, 2009 at the Monticello Nuclear Generating Plant (MNGP) an Operator made the following discovery during performance of his rounds. The flowrate and pressure of the #14 Residual Heat Removal Service Water (RHRSW) pump motor cooling appeared to be low. Investigation found the flow to be approximately 1 gpm. The cooling water supply flow to the pump motor cooler comes from either RHRSW or Service Water. Based on these indications, Operators declared the RHR Shutdown Cooling inoperable and entered actions for Technical Specifications 3.9.7. Actions have been completed to provide an alternate water supply to the RHRSW pump motor oil cooler. Based on the inoperability of the RHR Shutdown Cooling, this event is reportable under 10 CFR 50.72(b)(3)(v), 'An Event or Condition that could have Prevented the Fulfillment of a Safety Function-Capability to Remove Residual Heat.' The station is performing further investigation into the event and will develop corrective actions based on the results of the investigation.
The Licensee notified the NRC Resident Inspector.
Monticello is retracting the event reported based on further evaluation. An investigation of the event found test data that demonstrates the RHRSW pump would not have lost its ability to provide cooling water to the shutdown cooling system and therefore no loss of safety function occurred. The test data provides documentation that the thrust bearing oil bath temperature of the RHRSW pump motor would not have exceeded the 200 deg F limit imposed by the motor supplier (GE) at the flow rate found by the operator. The test data indicated with the cooling water at a flow rate of less than 0.9 GPM, at 65 deg F the service water temperature and flow would be sufficient to maintain the motor oil bath temperature below 200 deg F. During the event, the actual event parameters (cooling water flow rate >1 gpm and temperatures< 65 deg F) were less severe than the test parameters and therefore are bounded by the test. Since there was no impact on the RHRSW system's ability to provide cooling water to the RHR system, the RHR system maintained the ability to provide shutdown cooling and residual heat removal. Therefore the event can be retracted since the condition that was reported in the initial event notification report would not have resulted in the prevention of the fulfillment of a safety function (residual heat removal). The licensee notified the NRC Resident Inspector and will notify the State of Minnesota. Notified R3DO(Lara) |
| Where | |
|---|---|
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:+2.78 h0.116 days <br />0.0165 weeks <br />0.00381 months <br />) | |
| Opened: | Randy Sand 13:30 Apr 2, 2009 |
| NRC Officer: | Vince Klco |
| Last Updated: | May 28, 2009 |
| 44957 - NRC Website
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