Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 49355 | 18 September 2013 18:48:00 | On 9/18/13, during performance of the High Pressure Coolant Injection (HPCI) pump operability surveillance, a minor steam leak was discovered on the governor valve inspection cover flange. Due to the leak, HPCI was declared inoperable. Actions taken: A 14-day LCO per TS 3.5.E.2 has been entered and corrective actions are in progress. The licensee has notified the NRC Resident Inspector.
After further evaluation, the gasket leak at the flange was determined to have no impact on the operability of the HPCI system, and therefore the HPCI system was able to perform all safety functions with the identified condition. The immediate determination, made on September 18, 2013, that the HPCI system was inoperable was revised based on the results of an analysis of the HPCI room heat up rate. The heat up rate was modeled using a calculated steam leak rate based on actual measurements of the damaged gasket after removal from the HPCI turbine flange. The time to heat up was based on the first set point at which isolation due to a temperature increase would occur. It was determined that the existing gap in the gasket represented approximately one-tenth of the approximate size of a steam leak that would be expected to result in an isolation, therefore the existing flange leak had no impact on operability of the HPCI system or its ability to mitigate the consequences of an accident. The licensee has notified the NRC site Resident Inspector. Notified R1DO (Krohn). |
| ENS 47241 | 5 September 2011 09:40:00 | On 9/5/11 at 0403 EDT, Vermont Yankee Nuclear Power Station experienced a lightning strike which resulted in a loss of all vertical temperature difference instrumentation. This condition is being reported as a loss of emergency assessment capability in accordance with 10CFR50.72(b)(3)(xiii) Procedure OPOP-PHEN-3127, Natural Phenomena, was entered and the lightning damage indicator walkdown checklist was performed with no additional damage found. Several other spurious alarms were received at the time of the lightning strike and are being investigated. None of these alarms indicate any other potentially reportable conditions. The plant is continuing normal power operation at approximately 98 percent rated thermal power. The NRC Resident Inspector has been informed. The licensee reports that repairs are currently underway. |
| ENS 45987 | 8 June 2010 15:10:00 | On 6/8/10 at 10:15, primary containment was declared inoperable and a 24 (hour) Limiting Condition for Operation (LCO) was entered due to Engineered Safety Features leakage in excess of the 1.0 gpm value assumed in the Alternative Source Term (AST) analysis as described in the UFSAR. The leakage was from the 'B' RHR heat exchanger relief valve (SR-10-86B) and was estimated at 1.25 gpm. On 6/8/10 at 11:26, commenced a power reduction for a Technical Specification required shutdown per TS 3.7.A.8. Actions Taken: Isolating the 'B' RHR system per Technical Specifications that will allow us to exit the 24 hour LCO. Planning to replace the relief valve. Verified relief valve on 'A' RHR system is not leaking. The licensee has notified State and local authorities and the NRC Resident Inspector. The licensee also anticipates a press release.
The licensee exited the 24 hour LCO TS required shutdown condition at 1548 EDT based on isolation of the 'B' RHR system. R1DO (Henderson) notified. |
| ENS 45613 | 7 January 2010 16:55:00 | On January 6, 2010, Vermont Yankee (VY) was notified that the results of fourth quarter 2009 ground water sampling, performed as part of the voluntary ground water monitoring program, identified a very low concentration of tritium in one well that is used to monitor station ground water. VY has notified state, local and other government agencies of this condition. Since no other wells indicated the presence of tritium and the concentration detected is below the reporting threshold identified in the Off-site Dose Calculation Manual, notifications were considered voluntary consistent with NEI 07-07 'Industry Ground Water Initiative - Final Guidance Document.' This report is being made in accordance with 10 CFR 50.72(b)(2)(xi) to notify the NRC of these voluntary notifications. There is no impact on public health and safety as a result of this event. The NRC Resident Inspector has been notified. |
| ENS 44042 | 7 March 2008 13:00:00 | On 3/7/08, at 1045, Vermont Yankee experienced a telephone service interruption that resulted in a loss of the dedicated phone line used to contact the NRC Operations Center via the Emergency Notification System (ENS) - FTS phone as well as a loss of the Nuclear Alert System (NAS) from the control room. Alternate phone communications remain available from the control room to both the NRC Operations Center as well as the states of Vermont, Massachusetts, and New Hampshire. The Emergency Planning organization has verified proper ENS - FTS and NAS communications from the Emergency Operations Facility (EOF). The licensee notified the NRC Resident Inspector. * * * UPDATE FROM KRITZER TO SNYDER ON 3/7/08 AT 1552 * * * Vermont Yankee's ENS and other phone lines are back in service. The licensee notified the NRC Resident Inspector. Notified R1DO (Caruso). |