Event Notification Report for June 21, 2005
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
06/20/2005 - 06/21/2005
EVENT NUMBERS
41787
Power Reactor
Event Number: 41787
Facility: LASALLE
Region: 3 State: IL
Unit: [] [2] []
RX Type: [1] GE-5,[2] GE-5
NRC Notified By: JOHN WASHKO
HQ OPS Officer: JOHN KNOKE
Region: 3 State: IL
Unit: [] [2] []
RX Type: [1] GE-5,[2] GE-5
NRC Notified By: JOHN WASHKO
HQ OPS Officer: JOHN KNOKE
Notification Date: 06/22/2005
Notification Time: 05:56 [ET]
Event Date: 06/21/2005
Event Time: 23:40 [CDT]
Last Update Date: 06/23/2005
Notification Time: 05:56 [ET]
Event Date: 06/21/2005
Event Time: 23:40 [CDT]
Last Update Date: 06/23/2005
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
BRUCE BURGESS (R3)
BRUCE BURGESS (R3)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | Y | 100 | Power Operation | 100 | Power Operation |
MULTIPLE SPECIFIED SYSTEMS ACTUATIONS DUE TO LOSS OF AC SAFETY RELATED BUSES
"At 23:40 CDST, LaSalle Unit 2 experienced a trip of the 4160 Volt AC feed breaker to 480 Volt AC Safety Related buses 235X & 235Y. As a result of this feed breaker trip, containment isolation valves closed in multiple systems. The systems which isolated included Containment Monitoring System, Drywell Floor Drains and Drywell Equipment Drains, Reactor Recirculation Flow Control Hydraulic System, Drywell Instrument Nitrogen System, Reactor Water Cleanup System, and Reactor Recirculation Sample System. This event is reportable under 10 CFR50.72(b)(3)(iv)(A). In addition to the- above mentioned system isolations, the following plant responses occurred due to the loss of these 480 Volt AC buses: Reactor Building Ventilation was lost due to the closure of the secondary containment isolation dampers; Multiple Division 1 containment isolation valves lost their AC power source, a 1/2-SCRAM occurred due to the loss of the 2A Reactor Protection System Motor-Generator set, the DC charger feed to the Division 1 DC Battery/Bus was lost, and the battery is currently maintaining availability of DC power to the bus. Troubleshooting has determined that the cause of the breaker trip was due to a defective neutral ground current protective relay. This relay has been replaced and the buses have been re-energized. System restoration is currently in progress."
The plant is in multiple LCOs, however, the limiting LCO is a 12 hour requirement to reestablish operability to the DC Battery. The half scram has been restored and all ECCS systems can function correctly when required.
The licensee informed the NRC Resident Inspector.
* * * UPDATE FROM JEFF WILLIAMS TO GERRY WAIG AT 1217 EDT ON 06/22/05 * * *
"The following is an update to EN# 41787. Restoration of all required safety systems with the exception of the Reactor Core Isolation Cooling (RCIC) system has been completed. The associated ECCS systems were filled, vented and restored to an available status at 0630 CDST and full operability established at 0803 CDST. The Division 1 DC battery was fully recharged and returned to an operable status at 0803 CDST. Restoration of the RCIC system and investigation into the cause of the relay failure is currently in progress."
The licensee has notified the NRC Resident Inspector. Notified R3DO (Bruce Burgess) of the update.
"At 23:40 CDST, LaSalle Unit 2 experienced a trip of the 4160 Volt AC feed breaker to 480 Volt AC Safety Related buses 235X & 235Y. As a result of this feed breaker trip, containment isolation valves closed in multiple systems. The systems which isolated included Containment Monitoring System, Drywell Floor Drains and Drywell Equipment Drains, Reactor Recirculation Flow Control Hydraulic System, Drywell Instrument Nitrogen System, Reactor Water Cleanup System, and Reactor Recirculation Sample System. This event is reportable under 10 CFR50.72(b)(3)(iv)(A). In addition to the- above mentioned system isolations, the following plant responses occurred due to the loss of these 480 Volt AC buses: Reactor Building Ventilation was lost due to the closure of the secondary containment isolation dampers; Multiple Division 1 containment isolation valves lost their AC power source, a 1/2-SCRAM occurred due to the loss of the 2A Reactor Protection System Motor-Generator set, the DC charger feed to the Division 1 DC Battery/Bus was lost, and the battery is currently maintaining availability of DC power to the bus. Troubleshooting has determined that the cause of the breaker trip was due to a defective neutral ground current protective relay. This relay has been replaced and the buses have been re-energized. System restoration is currently in progress."
The plant is in multiple LCOs, however, the limiting LCO is a 12 hour requirement to reestablish operability to the DC Battery. The half scram has been restored and all ECCS systems can function correctly when required.
The licensee informed the NRC Resident Inspector.
* * * UPDATE FROM JEFF WILLIAMS TO GERRY WAIG AT 1217 EDT ON 06/22/05 * * *
"The following is an update to EN# 41787. Restoration of all required safety systems with the exception of the Reactor Core Isolation Cooling (RCIC) system has been completed. The associated ECCS systems were filled, vented and restored to an available status at 0630 CDST and full operability established at 0803 CDST. The Division 1 DC battery was fully recharged and returned to an operable status at 0803 CDST. Restoration of the RCIC system and investigation into the cause of the relay failure is currently in progress."
The licensee has notified the NRC Resident Inspector. Notified R3DO (Bruce Burgess) of the update.