Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 45518 | 24 November 2009 14:19:00 | On Monday, October 19, 2009, Limerick Unit 1 was operating at 100% power. At 1105 hours, an invalid actuation of the 1B Reactor Enclosure Ventilation Exhaust Radiation Monitor occurred. The actuation caused a Division 2 Group 6C isolation signal, which caused primary containment isolation valves (PCIVs) to automatically close on the Containment Leak Detector Radiation Monitor (10-S182) and the Drywell Hydrogen/Oxygen Analyzer (10-S205). The 1A, 1C, and 1D channels were unaffected and indicated normal ventilation exhaust radiation levels during the event. The cause of the event was a failure of a fuse holder in the 1B Reactor Enclosure Ventilation Exhaust Radiation Monitor. The radiation monitor is designed to fail-safe on a loss of power. The automatic closure of the PCIVs placed them in their fail-safe position. The failed fuse holder has been replaced and the radiation monitor was declared operable on Tuesday, October 20, 2009 at 1348 hours. The portion of the primary containment isolation system that received an actuation signal functioned successfully. All of the affected open isolation valves automatically closed. The only equipment malfunction during the event was the failed fuse holder. The Division 2 Group 6C isolation was a partial actuation. This event is reportable per 10CFR50.73(a)(2)(iv)(A) since isolation valves for the Containment Leak Detector Radiation Monitor and Drywell Hydrogen/Oxygen Analyzer automatically closed due to an invalid signal. The licensee notified the NRC Resident Inspector. |
| ENS 44283 | 11 June 2008 00:59:00 | On June 10, 2008, at 2255 hours it was determined that 54 of the 165 Limerick Generating Station's Emergency Offsite Sirens were inoperable due to a loss of power. The loss was a result of heavy storms which passed through the area resulting in power outages throughout the region. Efforts are underway to restore power to the affected sirens. The licensee notified the NRC Resident Inspector
On June 11, 2008 at 1645 restoration efforts have recovered 44 of the 54 sirens rendered inoperable by the storm. The remaining 10 inoperable sirens no longer represents a major loss of emergency preparedness capabilities. Restoration of power to the remaining inoperable sirens continues under normal prioritization and using routine siren operating and maintenance procedures. No completion time was provided concerning repair of the remaining sirens. The licensee will be notifying the NRC Resident Inspector. Notified R1DO (Summers). |
| ENS 43231 | 13 March 2007 15:14:00 | It was discovered that a valid Low Main Condenser Vacuum group 1A Nuclear Steam Supply Shutoff System (NS4) isolation for the Main Steam Isolation Valves (MSIV's) had been received while breaking main condenser vacuum while in Mode 4 for planned refueling outage 2R09. The isolation actuation was received as main condenser vacuum lowered below the isolation setpoint during the planned evolution of breaking of main condenser (vacuum). All valves for this isolation signal had previously been closed by approved plant procedures while in Mode 3. The valid isolation signal was caused by not having the isolation signal bypassed as allowed by approved plant procedures. The licensee will notify the NRC Resident Inspector. |