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| Entered date | Event description | |
|---|---|---|
| ENS 51628 | 30 December 2015 13:16:00 | This 60-day telephone notification is being made per the reporting requirements specified by 10CFR50.73(a)(2)(iv)(A) and 10CFR50.73(a)(1) to describe an invalid actuation of the Emergency AC electrical power systems, due to invalid start of an emergency diesel generator (EDG). On November 6, 2015, at 0815 (CST), EDG A received a fast start signal inadvertently. Maintenance Fix-It-Now (FIN) personnel, working in the vicinity of the relay panel, made incidental contact with one of the relays in the Diesel Generator Logic Relay Panel which initiated the engine start. The engine started and obtained rated speed and voltage in single unit mode. This was not a valid initiation of EDG A. Operations personnel responded to the EDG actuation by ensuring that the engine was shut down and placed in standby condition in accordance to plant operating instructions. The plant conditions at the time of the EDG A initiation would not have actuated the EDG; therefore, the actuation of EDG A was invalid. There were no safety consequences or impact to the health and safety of the public as a result of this event. This event was entered into the Corrective Action Program (CAP) as Condition Report (CR) 1101730. The NRC Resident Inspector was notified of this event. |
| ENS 48623 | 22 December 2012 16:39:00 | On 12/22/2012 at 1152 CST, the Unit 2 reactor automatically scrammed due to actuation of the Reactor Protection System (RPS) from loss of power to RPS. At 1134 CST, the D 4kV Shutdown Board unexpectedly de-energized during performance of post-maintenance testing for the 3D Diesel Generator paralleling circuitry, resulting in loss of power to the 2B RPS subsystem. Primary Containment Isolation System (PCIS) groups 2, 3, 6, and 8 isolations were received along with automatic initiation of A, B, and C Standby Gas Treatment subsystems and A Control Room Emergency Ventilation subsystem due to loss of power to the 2B RPS subsystem. While attempting to reenergize the 2B RPS subsystem, the 2A RPS subsystem was inadvertently de-energized resulting in Unit 2 reactor automatic scram. All affected safety systems responded as expected for the loss of RPS and reactor scram. Due to the loss of RPS, the Main Steam Isolation Valves (MSIVs) closed. Reactor pressure did not rise to the automatic initiation set point for Safety Relief Valve (SRV) actuation. Reactor Core Isolation Cooling System (RCIC) and High Pressure Coolant Injection System (HPCI) reactor water level initiation set point of -45" was reached and RCIC and HPCI automatically initiated as designed to restore water level above the initiation set point. Both Recirculation Pumps also tripped on reactor water level of -45". Reactor pressure control was established by manually operating one SRV and water level control established with RCIC. HPCI was returned to standby readiness. The scram was reset, MSIVs were opened, and the Main Condenser was established as a heat sink. The scram event from critical is reportable within 4 hours per 10 CFR 50.72(b)(2)(iv)(B). It is also reportable within 8 hours per 10 CFR 50.72(b)(3)(iv)(A) and requires an LER within 60 days per 10 CFR 50.73(a)(2)(iv)(A). The NRC Resident Inspector was notified. The 2A and 2B RPS subsystems were returned to service. The electrical grid is stable and supplying shutdown loads on Unit 2. Unit 1 and Unit 3 were unaffected and continue to operate at 100% power. |
| ENS 46066 | 2 July 2010 14:23:00 | This 60 day telephone notification is being made in-lieu of a written report under the requirements specified by 10 CFR 50.73(a)(2)(iv) and 10 CFR 50.73(a)(1) to describe an invalid actuation of general containment isolation signals affecting more than one system. On May 12, 2010, at 1232 hours Central Daylight Time (CDT), with Unit 3 operating at 100 percent thermal power the electrical power to the 3A RPS was interrupted during the transfer of the 3A 480V shutdown board from its alternate supply to its normal power supply. During the transfer, the normal breaker did not close for several seconds. This resulted in the interruption of power to the 3A shutdown board which caused the 3A RPS to de-energize, resulting in a half scram and the actuation of PCIS logic Groups 2, 3, 6, and 8, and the initiation of Trains B and C of Standby Gas Treatment, and the initiation of Train A Control Room Emergency Ventilation. Plant conditions which require PCIS actuations and the associated system initiations (e.g., low reactor water level, high drywell pressure, abnormal area radiation level, or high area temperature) did not exist; therefore, the actuation was invalid. The affected equipment responded as designed. On May 12, 2010, by approximately 1342 hours CDT, Unit 3 operations personnel restored the 3A RPS power and realigned affected equipment as appropriate. There were no safety consequences or impact on the health and safety of the public as a result of this event. The event was entered into the corrective actions program as PER 229613. The NRC Senior Resident Inspector has been notified. |
| ENS 45950 | 24 May 2010 19:24:00 | Browns Ferry Nuclear Plant (BFN) is notifying state and local agencies of an oil sheen at the Intake Structure Forebay of approximately 1 gallon. The sheen came from a center motor oil leak on Intake Structure Gate #3. Leak has been secured and oil sheen Is being cleaned up. BFN Procedure RWI-007, Spill Prevention Control and Countermeasure Plan requires the National Response Center as well as other state and local agencies be notified of any oil sheen on the water. This event is reportable as a 4-hour Non-Emergency Notification report in accordance with 10CFR50.72(b)(2)(xi) Any event or situation, related to the health and safety of the public or onsite personnel, or protection of the environment, for which a news release is planned or notification to other government agencies has been or will be made. The licensee notified the NRC Resident Inspector. |