U.S. Nuclear Regulatory Commission
Event Reports For
01/12/2011 - 01/13/2011
** EVENT NUMBERS **
|Power Reactor ||Event Number: 46535 |
| Facility: QUAD CITIES |
Region: 3 State: IL
Unit: [ ]  [ ]
RX Type:  GE-3, GE-3
NRC Notified By: KEN HILL
HQ OPS Officer: JOHN SHOEMAKER
| Notification Date: 01/12/2011 |
Notification Time: 15:16 [ET]
Event Date: 01/12/2011
Event Time: 10:20 [CST]
Last Update Date: 01/12/2011
| Emergency Class: NON EMERGENCY |
10 CFR Section:
50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
| Person (Organization): |
MICHAEL KUNOWSKI (R3DO)
|Unit ||SCRAM Code ||RX CRIT ||Initial PWR ||Initial RX Mode ||Current PWR ||Current RX Mode |
|2 ||N ||Y ||100 ||Power Operation ||100 ||Power Operation |
|LOSS OF UNIT 2 ESSENTIAL SERVICE 480V BUS |
"On January 12, 2011, at 1020 hours, Unit 2 480V Essential Service Bus 29 was inadvertently deenergized. The cause of the bus trip was inadvertent contact with a bus feed breaker by a station employee during unrelated work activities. Normal power to Bus 29 was restored at 1026 hours. While Bus 29 was deenergized Division II core and containment cooling systems were unavailable and inoperable.
"The plant responded normally to the loss of Bus 29 with the exception of Bus 28/29-5 which should have automatically transferred from Bus 29 to the reserve feed from Bus 28. This condition renders both divisions of the Low Pressure Cooling Injection (LPCI) mode of the Residual Heat Removal (RHR) system inoperable. Technical Specifications 3.5.1.E has been entered, requiring restoration of LPCI in 72 hours.
"Bus 28/29-5 was manually energized from Bus 28 at 1213 hours; however, LPCI remains inoperable pending investigation and restoration of Bus 28/29-5 auto-transfer function.
"This event is reportable under 10 CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented fulfillment of a safety function."
LPCI mode of the RHR system is inoperable because the auto-transfer function for Bus 28/29-5 provides a back-up power supply to the LPCI injection motor operated valves from Bus 28.
A swing diesel test was in progress during this bus loss, however the diesel was not loaded and had no impact on the bus failure. The diesel was subsequently secured.
The licensee notified the NRC Resident Inspector.