ENS 47449
ENS Event | |
|---|---|
22:00 Nov 16, 2011 | |
| Title | Hpci Declared Inoperable Due to Dual Position Indication on Closed Steam Admission Isolation Valve |
| Event Description | On November 16, 2011, at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> [EST], with the reactor at 100% core thermal power and steady state conditions, the High Pressure Coolant Injection (HPCI) system was removed from service for planned testing and the appropriate Limiting Condition for Operation was entered (14 days per TS 3.5.C.2). At 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> during restoration from the testing, the normally closed HPCI steam admission isolation valve (HPCI-2301-3) displayed dual indication (not full closed). The HPCI-2301-3 is a motor-operated valve (MOV) whose safety function is to open upon a HPCI injection/actuation signal.
The Limiting Condition for Operation (LCO) that had been entered in a planned manner was continued as of 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> due to the apparent degraded performance of the HPCI-2301-3 valve. Currently, troubleshooting into the cause of the anomalous dual indication on HPCI-2301-3 is in progress. However, it is projected that the troubleshooting will not be complete within reportability assessment requirements. Therefore, in accordance with 50.72(b)(3)(v)(D), Pilgrim Nuclear Power Station is providing an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> non-emergency notification that the HPCI System is inoperable. This event had no impact on the health and/or safety of the public. The NRC Resident Inspector has been notified.
The licensee is retracting this report based on the following: Event Notification Number 47449 was conservatively made to ensure that the Eight-Hour Non-Emergency reporting requirements of 10 CFR 50.72 were satisfied pending further evaluation of HPCI system operability due to dual valve position indication when the HPCI Turbine Steam Supply Valve (MO-2301-3) valve was taken to the fully closed position after HPCI system surveillance testing from the Alternate Shutdown Panel. Evaluation of the MO-2301-3 valve condition was performed. The dual position indication from the valve position instrumentation was determined to be valid based on the as-found valve position. The valve did not fully close because the torque switch opened prematurely due to high stem torque. The apparent cause evaluation identified that a lack of grease due to a tight stem to valve configuration and inadequate guidance to perform proper periodic stem lubrication were the apparent cause of the valve closure failure. The valve is limit switch controlled in the open direction and torque switch controlled in the closed direction. The valve is normally closed and has no automatic closing function necessary to ensure HPCI System safety functions are satisfied. The valve has an active safety function to open to allow steam to the HPCI Turbine. The surveillance test that was performed verified capability of the valve to open on demand. Based on the surveillance test, failure of the HPCI Turbine Steam Supply Valve to close would not have prevented the HPCI System from operating and meeting required safety functions. Therefore, the initial 50.72(b)(3)(v)(D) report is being retracted. The licensee will inform the NRC Resident Inspector. Notified R1DO (Trapp). |
| Where | |
|---|---|
| Pilgrim Massachusetts (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+1.27 h0.0529 days <br />0.00756 weeks <br />0.00174 months <br />) | |
| Opened: | Ken Goodall 23:16 Nov 16, 2011 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Jan 16, 2012 |
| 47449 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |