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At 14:34 hours on June 24, 2010, with the … At 14:34 hours on June 24, 2010, with the unit in MODE 5, Cold Shutdown, with approximately 50% pressurizer level, during Refueling Outage 26, Instrument Buses 3 and 8 unexpectedly de-energized during performance of testing in accordance with procedure OST-163, 'Safety Injection Test and Emergency Diesel Generator Auto Start on Loss of Power and Safety Injection.' The loss of Instrument Buses 3 and 8 occurred during the loss of power and Safety Injection testing of the 'A' Train. </br>Instrument Buses 3 and 8 are normally powered from Inverter 'B' which is normally supplied by the Train 'B' DC Bus. During the test, it was noted that the power supply to Instrument Buses 3 and 8 had tripped. The cause of the failure of Inverter 'B' is not currently known. The failure of inverter 'B' caused the closure of the Residual Heat Removal (RHR) Heat Exchanger discharge valve (HCV-758) and the RHR Heat Exchanger bypass valve (FCV-605). </br>Both trains of RHR continued to operate and reactor coolant system temperature remained in the range of approximately 93 to 96 degrees Fahrenheit. Abnormal Operating Procedure AOP-020, 'Loss of Residual Heat Removal (Shutdown Cooling)' was entered. Power was restored to Instrument Buses 3 and 8 by use of the alternate power supply at 14:49 hours. Normal configuration of the RHR system was restored and AOP-020 was exited at 14:51 hours. </br>Currently Instrument Buses 3 and 8 are being powered from the alternate power supply which causes the associated 'B' EDG to be inoperable due to the inoperability of the automatic load sequencer that starts the associated Service Water and Component Cooling Water pumps. The 'A' EDG is inoperable due to the need to complete required post-maintenance testing. Therefore, both EDGs are currently inoperable.</br>Both EDGs are currently considered available and are aligned for automatic starting. Both EDGs would be expected to automatically supply their respective buses if a loss of offsite power were to occur. Manual action would be required to start the required loads on the 'B' Train due to the current alignment of the Instrument Buses 3 and 8 on the alternate power supply.</br>It is expected that the 'B' EDG will be restored to operable status when Inverter 'B' is restored to operable status and realigned to supply Instrument Buses 3 and 8.</br>The Technical Specifications (TS) Action Statement currently in effect for loss of Inverter 'B' (TS 3.8.8 Condition A) requires initiation of action to restore AC instrument bus sources to OPERABLE status immediately. The actions to restore Inverter 'B' were initiated immediately and are continuing.</br>This report is being made in accordance with 10 CFR 50.72(b)(3)(v)(D), for any event or condition that at the time of discovery could have prevented the fulfillment of structures or systems that are needed to mitigate the consequences of an accident.</br>The licensee has notified the NRC Resident Inspector.</br>* * * UPDATE AT 1408 ON 6/27/2010 FROM ASHLEY VALONE TO MARK ABRAMOVITZ * * *</br>This is a follow-up notification to Event Notification EN #46045 regarding Instrument Buses 3 and 8 that unexpectedly de-energized during performance of testing in accordance with procedure OST-163, 'Safety Injection Test and Emergency Diesel Generator Auto Start on Loss of Power and Safety Injection.' </br>Power was restored to Instrument Buses 3 and 8 by use of the normal power supply at 08:03 hours on June 27, 2010. Inverter 'B' has been realigned to supply Instrument Buses 3 and 8. The restoration of inverter 'B' has returned the associated 'B' EDG to operable status at 11:09 hours with the return of the automatic load sequencer that starts the associated Service Water and Component Cooling Water pumps. The 'A' EDG continues to be inoperable due to the need to complete required post-maintenance testing. Currently 'A' EDG is considered available and aligned for automatic starting.</br>The Technical Specifications (TS) Action Statement for loss of Inverter 'B' (TS 3.8.8 Condition A) that requires initiation of action to restore AC instrument bus sources to OPERABLE status immediately was exited at 11:09 hours on June 27, 2010. TS Action Statement for loss of 'B' EDG (TS 3.8.2 Condition B) that requires initiation of action to restore required DG to OPERABLE status immediately was also exited at 11:09 hours on June 27, 2010.</br>The licensee is still investigating the cause of the failure.</br>The licensee notified the NRC Resident Inspector.</br>Notified the R2DO (Shaeffer).t Inspector.
Notified the R2DO (Shaeffer).
18:34:00, 24 June 2010 +
46,045 +
21:34:00, 24 June 2010 +
18:34:00, 24 June 2010 +
At 14:34 hours on June 24, 2010, with the … At 14:34 hours on June 24, 2010, with the unit in MODE 5, Cold Shutdown, with approximately 50% pressurizer level, during Refueling Outage 26, Instrument Buses 3 and 8 unexpectedly de-energized during performance of testing in accordance with procedure OST-163, 'Safety Injection Test and Emergency Diesel Generator Auto Start on Loss of Power and Safety Injection.' The loss of Instrument Buses 3 and 8 occurred during the loss of power and Safety Injection testing of the 'A' Train. </br>Instrument Buses 3 and 8 are normally powered from Inverter 'B' which is normally supplied by the Train 'B' DC Bus. During the test, it was noted that the power supply to Instrument Buses 3 and 8 had tripped. The cause of the failure of Inverter 'B' is not currently known. The failure of inverter 'B' caused the closure of the Residual Heat Removal (RHR) Heat Exchanger discharge valve (HCV-758) and the RHR Heat Exchanger bypass valve (FCV-605). </br>Both trains of RHR continued to operate and reactor coolant system temperature remained in the range of approximately 93 to 96 degrees Fahrenheit. Abnormal Operating Procedure AOP-020, 'Loss of Residual Heat Removal (Shutdown Cooling)' was entered. Power was restored to Instrument Buses 3 and 8 by use of the alternate power supply at 14:49 hours. Normal configuration of the RHR system was restored and AOP-020 was exited at 14:51 hours. </br>Currently Instrument Buses 3 and 8 are being powered from the alternate power supply which causes the associated 'B' EDG to be inoperable due to the inoperability of the automatic load sequencer that starts the associated Service Water and Component Cooling Water pumps. The 'A' EDG is inoperable due to the need to complete required post-maintenance testing. Therefore, both EDGs are currently inoperable.</br>Both EDGs are currently considered available and are aligned for automatic starting. Both EDGs would be expected to automatically supply their respective buses if a loss of offsite power were to occur. Manual action would be required to start the required loads on the 'B' Train due to the current alignment of the Instrument Buses 3 and 8 on the alternate power supply.</br>It is expected that the 'B' EDG will be restored to operable status when Inverter 'B' is restored to operable status and realigned to supply Instrument Buses 3 and 8.</br>The Technical Specifications (TS) Action Statement currently in effect for loss of Inverter 'B' (TS 3.8.8 Condition A) requires initiation of action to restore AC instrument bus sources to OPERABLE status immediately. The actions to restore Inverter 'B' were initiated immediately and are continuing.</br>This report is being made in accordance with 10 CFR 50.72(b)(3)(v)(D), for any event or condition that at the time of discovery could have prevented the fulfillment of structures or systems that are needed to mitigate the consequences of an accident.</br>The licensee has notified the NRC Resident Inspector.</br>* * * UPDATE AT 1408 ON 6/27/2010 FROM ASHLEY VALONE TO MARK ABRAMOVITZ * * *</br>This is a follow-up notification to Event Notification EN #46045 regarding Instrument Buses 3 and 8 that unexpectedly de-energized during performance of testing in accordance with procedure OST-163, 'Safety Injection Test and Emergency Diesel Generator Auto Start on Loss of Power and Safety Injection.' </br>Power was restored to Instrument Buses 3 and 8 by use of the normal power supply at 08:03 hours on June 27, 2010. Inverter 'B' has been realigned to supply Instrument Buses 3 and 8. The restoration of inverter 'B' has returned the associated 'B' EDG to operable status at 11:09 hours with the return of the automatic load sequencer that starts the associated Service Water and Component Cooling Water pumps. The 'A' EDG continues to be inoperable due to the need to complete required post-maintenance testing. Currently 'A' EDG is considered available and aligned for automatic starting.</br>The Technical Specifications (TS) Action Statement for loss of Inverter 'B' (TS 3.8.8 Condition A) that requires initiation of action to restore AC instrument bus sources to OPERABLE status immediately was exited at 11:09 hours on June 27, 2010. TS Action Statement for loss of 'B' EDG (TS 3.8.2 Condition B) that requires initiation of action to restore required DG to OPERABLE status immediately was also exited at 11:09 hours on June 27, 2010.</br>The licensee is still investigating the cause of the failure.</br>The licensee notified the NRC Resident Inspector.</br>Notified the R2DO (Shaeffer).t Inspector.
Notified the R2DO (Shaeffer).
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00:00:00, 27 June 2010 +
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18:34:00, 24 June 2010 +
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