Event Notification Report for September 12, 2004
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
09/11/2004 - 09/12/2004
EVENT NUMBERS
41037
Power Reactor
Event Number: 41037
Facility: OCONEE
Region: 2 State: SC
Unit: [1] [] []
RX Type: [1] B&W-L-LP,[2] B&W-L-LP,[3] B&W-L-LP
NRC Notified By: NOEL CLARKSON
HQ OPS Officer: HOWIE CROUCH
Region: 2 State: SC
Unit: [1] [] []
RX Type: [1] B&W-L-LP,[2] B&W-L-LP,[3] B&W-L-LP
NRC Notified By: NOEL CLARKSON
HQ OPS Officer: HOWIE CROUCH
Notification Date: 09/12/2004
Notification Time: 19:14 [ET]
Event Date: 09/12/2004
Event Time: 15:55 [EDT]
Last Update Date: 09/12/2004
Notification Time: 19:14 [ET]
Event Date: 09/12/2004
Event Time: 15:55 [EDT]
Last Update Date: 09/12/2004
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
10 CFR Section:
50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Person (Organization):
CAROLYN EVANS (R2)
CAROLYN EVANS (R2)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
BOTH TRAINS OF REACTOR BUILDING SPRAY INOPERABLE FOR THREE MINUTES
The following information was obtained from the licensee via facsimile:
"With the 1A Reactor Building Spray (RBS) train declared inoperable, due to an inoperable ES [Engineered Safeguards] digital channel, the suction valve to the 1B RBS train was stroked closed, rendering the 1B RBS train inoperable, concurrent with the 1A RBS train inoperability. The duration of the valve stroke, and dual RBS train inoperability was 3 minutes. This dual RBS train inoperability resulted in entry into TS [Technical Specification] 3.0.3 for the 3 minute duration of the valve stroke.
"At the time of this event, all three Reactor Building Cooling Unit (RBCU) trains were operable. The RBCUs provide a redundant, post-accident, containment heat removal function to the RBS trains. However, the RBS system is credited with post-accident iodine removal for the maximum hypothetical accident. Additionally, should an Engineered Safeguards actuation have occurred during the 3 minute stroke time, the RBS pumps in the 1B train would have started without the suction valve being fully open. This degraded suction flow could have impacted proper RBS pump operation in the event of an ES actuation.
"The 1B RBS train suction valve stroke was completed before it was noted that the valve stroke had resulted in the inoperability of the 1B RBS train, concurrent with the inoperability of the 1A RBS train. The 1B RBS train suction valve has been returned to an open condition and the 1B RBS train is currently operable."
The operations personnel were performing valve stroke time surveillances when the event occurred.
The licensee has notified the NRC Resident Inspector.
The following information was obtained from the licensee via facsimile:
"With the 1A Reactor Building Spray (RBS) train declared inoperable, due to an inoperable ES [Engineered Safeguards] digital channel, the suction valve to the 1B RBS train was stroked closed, rendering the 1B RBS train inoperable, concurrent with the 1A RBS train inoperability. The duration of the valve stroke, and dual RBS train inoperability was 3 minutes. This dual RBS train inoperability resulted in entry into TS [Technical Specification] 3.0.3 for the 3 minute duration of the valve stroke.
"At the time of this event, all three Reactor Building Cooling Unit (RBCU) trains were operable. The RBCUs provide a redundant, post-accident, containment heat removal function to the RBS trains. However, the RBS system is credited with post-accident iodine removal for the maximum hypothetical accident. Additionally, should an Engineered Safeguards actuation have occurred during the 3 minute stroke time, the RBS pumps in the 1B train would have started without the suction valve being fully open. This degraded suction flow could have impacted proper RBS pump operation in the event of an ES actuation.
"The 1B RBS train suction valve stroke was completed before it was noted that the valve stroke had resulted in the inoperability of the 1B RBS train, concurrent with the inoperability of the 1A RBS train. The 1B RBS train suction valve has been returned to an open condition and the 1B RBS train is currently operable."
The operations personnel were performing valve stroke time surveillances when the event occurred.
The licensee has notified the NRC Resident Inspector.