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On March 30, 2011 at 1443 CDT, during a re … On March 30, 2011 at 1443 CDT, during a refueling outage, Browns Ferry Unit 2 received an invalid Common Accident Signal (CAS) as a result of maintenance activities. All four Unit 1/2 diesel (generators) auto started and all four Unit 3 diesel (generators) auto started. Unit 2 received a full Reactor SCRAM and Core Spray pumps A, B, C, and D auto started and injected into the reactor. Unit 2 Division I RHR (Residual Heat Removal) system was in Shutdown Cooling with only the C pump in service. The A RHR pump auto started and Shutdown Cooling flow increased, as expected. Unit 2 Division II RHR system was tagged out for maintenance. HPCI (High Pressure Coolant Injection) and RCIC (Reactor Core Isolation Cooling) received auto initiation signals, however the steam isolation valves were tagged closed and the systems did not start. MSIVs (Main Steam Isolation Valves) isolated as a result of the CAS signal.</br>Unit 1 was at 100% power when the CAS on Unit 2 occurred. This caused initiation of the Preferred Pump Logic which designates Division I CS (Core Spray) and LPCI (Low Pressure Coolant Injection) pumps on Unit 1 (1A and 1C) and the Division II pumps on Unit 2 (2B and 2D) and prevents Unit 1 Division II pumps from auto starting. This resulted in the Division II RHR and CS pumps (being) inoperable for Unit 1. Unit 1 subsequently entered Technical Specification 3.5.1, Condition H (two or more low pressure ECCS (Emergency Core Cooling System) injection/spray subsystems inoperable) which requires entering LCO 3.0.3 immediately.</br>Unit 1 entered LCO 3.0.3 at 1443, which requires that actions shall be initiated within one hour to place the unit in Mode 2 within 10 hours; Mode 3 within 13 hours; and Mode 4 within 37 hours. At 1542 Unit 1 began lowering power in order to comply with LCO 3.0.3.</br>CAS logic was reset at 1812 and Unit 1 exited LCOs 3.5.1.H and 3.0.3.</br>This condition requires a four hour report in accordance with 50.72(b)(2)(i) - 'The initiation of any nuclear plant shutdown required by the plant's Technical Specifications.'</br>The NRC Resident Inspector was notified. Service Request #346544 was initiated in the Corrective Action Program.nitiated in the Corrective Action Program.
20:42:00, 30 March 2011 +
19:57:00, 30 March 2011 +
20:42:00, 30 March 2011 +
On March 30, 2011 at 1443 CDT, during a re … On March 30, 2011 at 1443 CDT, during a refueling outage, Browns Ferry Unit 2 received an invalid Common Accident Signal (CAS) as a result of maintenance activities. All four Unit 1/2 diesel (generators) auto started and all four Unit 3 diesel (generators) auto started. Unit 2 received a full Reactor SCRAM and Core Spray pumps A, B, C, and D auto started and injected into the reactor. Unit 2 Division I RHR (Residual Heat Removal) system was in Shutdown Cooling with only the C pump in service. The A RHR pump auto started and Shutdown Cooling flow increased, as expected. Unit 2 Division II RHR system was tagged out for maintenance. HPCI (High Pressure Coolant Injection) and RCIC (Reactor Core Isolation Cooling) received auto initiation signals, however the steam isolation valves were tagged closed and the systems did not start. MSIVs (Main Steam Isolation Valves) isolated as a result of the CAS signal.</br>Unit 1 was at 100% power when the CAS on Unit 2 occurred. This caused initiation of the Preferred Pump Logic which designates Division I CS (Core Spray) and LPCI (Low Pressure Coolant Injection) pumps on Unit 1 (1A and 1C) and the Division II pumps on Unit 2 (2B and 2D) and prevents Unit 1 Division II pumps from auto starting. This resulted in the Division II RHR and CS pumps (being) inoperable for Unit 1. Unit 1 subsequently entered Technical Specification 3.5.1, Condition H (two or more low pressure ECCS (Emergency Core Cooling System) injection/spray subsystems inoperable) which requires entering LCO 3.0.3 immediately.</br>Unit 1 entered LCO 3.0.3 at 1443, which requires that actions shall be initiated within one hour to place the unit in Mode 2 within 10 hours; Mode 3 within 13 hours; and Mode 4 within 37 hours. At 1542 Unit 1 began lowering power in order to comply with LCO 3.0.3.</br>CAS logic was reset at 1812 and Unit 1 exited LCOs 3.5.1.H and 3.0.3.</br>This condition requires a four hour report in accordance with 50.72(b)(2)(i) - 'The initiation of any nuclear plant shutdown required by the plant's Technical Specifications.'</br>The NRC Resident Inspector was notified. Service Request #346544 was initiated in the Corrective Action Program.nitiated in the Corrective Action Program.
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