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| Entered date | Event description | |
|---|---|---|
| ENS 51527 | 10 November 2015 20:13:00 | On 11/10/2015 at 1502 (EST), Unit 2 MCR (main control room) was notified by workers in containment that 2 ice suits had been dropped into the Unit 2 Containment Reactor Cavity Equipment Pit. Based upon size and location of the dropped suits, Unit 2 entered LCO 3.6.15 (Containment Recirculation Drains) Condition B and LCO 3.0.3 for refueling canal drains being inoperable. The two refueling canal drains and the ice condenser drains function with the ice bed, Containment Spray System and ECCS to limit the pressure and temperature that could be expected following a DBA (Design Basis Accident). Following performance of a Safety Function Determination it was determined that, during the short duration when both coats were in the process of being retrieved, they could have potentially clogged the drains and prevented the fulfillment of safety functions if there was a DBA. Both suits were retrieved from the equipment pit by 1556 (EST) and all LCO conditions were exited. The licensee notified the NRC Resident Inspector. |
| ENS 51259 | 24 July 2015 17:04:00 | At 1351 EDT on 7/24/2015, Sequoyah Unit 1 reactor/turbine automatically tripped. Following the reactor trip, all safety-related equipment operated as designed. Auxiliary Feedwater automatically initiated as expected from the Feedwater Isolation Signal. 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 and decay heat removal via the condenser steam dumps. The immediate cause of the trip was an electrically-induced turbine trip. There was no associated work in progress related to this and all systems were normally aligned. There is no indication of any primary/secondary leakage. All rods fully inserted on the reactor trip and remain inserted. The electrical alignment is normal with shutdown power supplied from off-site power. The 2B-B Emergency Diesel Generator is currently in service for the performance of an unrelated surveillance. There is no operational impact to Unit 2. Unit 2 continues to operate in Mode 1 at 100%. There was no impact on public health and safety. Post-trip investigation is in progress and planned restart timeline has not yet been determined. The licensee notified the NRC Resident Inspector. The cause of the main generator lockout is under investigation. |