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| Entered date | Event description | |
|---|---|---|
| ENS 47081 | 21 July 2011 00:53:00 | At 2129 EST on 7/20/2011, Unit 1 reactor/turbine automatically tripped. Following the reactor trip, all safety-related equipment operated as designed. Auxiliary Feedwater automatically actuated as expected from the Feedwater Isolation Signal. Primary PORVs and/or safety valves lifted and reseated as indicated by tailpipe temperatures and PRT pressure. Unit 1 is currently being maintained in Mode 3 at NOT/NOP, approximately 548 F and 2235 psig, with Auxiliary Feedwater supplying the steam generators. At the time of the trip, maintenance was in progress on Preferred Inverter #1. AOP-P.09 'Loss of 120VAC Preferred Power' was used to restore power to #1 Preferred board after the trip. Method of decay heat removal is via steam dumps to the condenser with MSIVs open. Current temperature and pressure: Temperature - 548 degrees Fahrenheit and stable, Pressure 2235 - psig and stable No indication of any primary/secondary leakage. All rods are inserted. Electrical alignment is normal, supplied from off-site power. No impact on Unit 2. Unit 2 is operating at 100% power/Mode 1 The NRC Resident Inspector has been informed. The licensee notified the State of Tennessee. |
| ENS 47249 | 8 September 2011 10:34:00 | This report is a 60-day telephone notification in lieu of a written licensee event report being made under 10CFR50.73(a)(2)(iv)(A) and 10CFR50.73(a)(1). The event was an invalid actuation of a Unit 2 Containment Ventilation Isolation (CVI). At the time of the event Unit 1 was at 100% power and Unit 2 was at 85% power. At 1520 EDT on 5/5/2011, an 'A' train CVI signal was inadvertently initiated during a surveillance test for containment purge air exhaust radiation monitor 2-RM-90-130. The inadvertent CVI signal was initiated due to incorrect connection of test equipment. The signal caused the 'A' train containment upper and lower compartment radiation monitor isolation valves to close. Unit 2 entered Technical Specification Limiting Condition for Operation (LCO) 3.3.3.1 Action 27 and LCO 3.4.6.1 Action b, due to the isolation of lower compartment radiation monitor 2-RM-90-106. The inadvertent CVI signal was also received by the containment vent system, but the containment vent system was not in service and no valves were actuated. The radiation monitoring (system 90) and the containment vent (system 30) systems received a complete 'A' train CVI signal. The 'A' train radiation monitoring isolation valves closed as designed. The containment vent system was not in service, and since the valves were already closed, no valves were actuated. Actual plant conditions did not exist that required a CVI signal. Therefore, this actuation was invalid. The delay in reporting this event was due to an initial interpretation that the event did not result in an actuation of the systems listed in paragraph 10CFR50.73(a)(2)(iv)(B), because only one system was in service which was affected by the actuation. Subsequent discussions noted that while only one system was in service, both systems received the CVI signal. The event is reported as a 60-day telephone notification in lieu of a written licensee event report being made under 10CFR50.73(a)(2)(iv)(A) and 10CFR50.73(a)(1). The date, when the final determination of the invalid system actuation was made, was not provided. The licensee notified the NRC Resident Inspector. |