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| Entered date | Event description | |
|---|---|---|
| ENS 50134 | 23 May 2014 15:32:00 | At 1210 EDT on Friday, May 23, 2014, the Massachusetts Department of Environmental Protection and the Plymouth Massachusetts Fire Department were notified of a hydrogen release in accordance with plant procedures and 310CMR40.300, Massachusetts Contingency Plan Notification for Oil and Hazardous Material; Identification and Listing of Oil and Hazardous Material. This was due to a release of hydrogen gas to the environment exceeding the reportable quantity of ten pounds. The release was from the generator hydrogen cooling system. There was no plant damage. Hydrogen system pressure has been restored to the normal operating band and is stable. The cause of the event is under investigation. This event posed no danger to the health and safety of plant personnel or members of the general public. The NRC Resident Inspector has been notified. |
| ENS 49454 | 19 October 2013 09:57:00 | On Saturday, October 19, 2013 at 0331 hours, with the reactor critical at approximately 1% core thermal power and the mode switch in start-up, a high reactor water level condition resulted in a main turbine trip and a valid Group 1 isolation signal. As a result, the Main Steam Isolation Valves (MSIVs) closed. The plant was in start-up from a forced outage. The initial plant conditions were reactor pressure at approximately 280 psig with a corresponding reactor coolant temperature for that pressure. Currently reactor pressure and water level are being maintained with the MSIVs closed in normal bands. The reactor is being cooled down in preparation for operation in shutdown cooling. Off-site power is supplying station power from the Start-up Transformer (normal power supply for shutdown operations). All plant systems responded as designed. The cause of the increase in reactor water level is currently under investigation. This event had no impact on the health and/or safety of the public. The USNRC Senior Resident Inspector has been notified. |
| ENS 47449 | 16 November 2011 23:16:00 | On November 16, 2011, at 1600 hours (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 hours 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 hours 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 hour 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). |
| ENS 42597 | 22 May 2006 22:05:00 | During ongoing activities to remove non-fuel material from the Pilgrim Spent Fuel Pool it has been identified that an irradiated neutron detector containing a very small quantity (less than 0.003 grams) of special nuclear material is not in its expected location. Per the inventory sheets the neutron detector should have been enclosed in a "dry tube" in the Spent Fuel Pool. Processing of the "dry tube" for shipment identified that the neutron detector is not in its expected location. This condition is being conservatively reported under 10CFR74.11. There is no evidence of theft or diversion. Investigation is continuing. The licensee notified the NRC Resident Inspector.
In Event Notifications 42597 and 42599 on May 22 and May 23, 2006, respectively, Pilgrim Nuclear Power Station notified the NRC that during ongoing activities to remove non-fuel material from the Pilgrim Spent Fuel Pool it had been identified that 2 irradiated neutron detectors containing very small quantities (less than 0.003 grams each) of special nuclear material were not in their expected locations. Per the inventory sheets the neutron detectors should have been enclosed in 'dry tubes' in the Spent Fuel Pool. Processing of the 'dry tubes' identified that the neutron detectors are not in their expected locations. There were a total of twelve (12) 'dry tubes' that our records show enclosed neutron detectors. As part of the investigation associated with Event Notification 42597, all twelve (12) of these 'dry tubes' have been inspected. Three (3) of the 'dry tubes' were found to contain neutron detectors consistent with plant records. Nine (9) of the 'dry tubes' were found to contain no neutron detector which is not consistent with the plant records. The irradiated neutron detectors would have each contained a very small quantity (less than 0.003 grams each) of special nuclear material. This condition is being conservatively reported under 10CFR74.11. There is no evidence of theft or diversion. Investigation is continuing. The licensee notified the NRC Resident Inspector. Notified IRD (Blount and Leach), R1DO (Gray), NRR (Haney), ILTAB (English), DHS SWO (Cassandra), FEMA (S. Kimbrell), DOE (Ronnie), EPA (Crews), USDA (Margaret), and HHS (Marcy). |