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Event Notification Report for June 22, 2005

U.S. Nuclear Regulatory Commission
Operations Center

Event Reports For
06/21/2005 - 06/22/2005

** EVENT NUMBERS **


41786

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Power Reactor Event Number: 41786
Facility: WOLF CREEK
Region: 4 State: KS
Unit: [1] [ ] [ ]
RX Type: [1] W-4-LP
NRC Notified By: EDWIN TAYLOR
HQ OPS Officer: MARK ABRAMOVITZ
Notification Date: 06/21/2005
Notification Time: 16:35 [ET]
Event Date: 05/10/2005
Event Time: 16:55 [CDT]
Last Update Date: 06/21/2005
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(ii)(B) - UNANALYZED CONDITION
Person (Organization):
RUSSELL BYWATER (R4)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
1 N N 0 Cold Shutdown 0 Cold Shutdown

Event Text

EMERGENCY SAFETY SYSTEM ACTUATION DAMPERS INOPERABLE

"During integrated ESFAS System Testing coming out of RF 14, it was noted [on 5/10/05] that 4 dampers receiving an SI signal did not reposition full closed as required. The dampers serve to isolate the Condenser Air Removal Ductwork in the Turbine Building from the Filtration train in the Auxiliary Building. Failure of these dampers to close was determined on 05/27/2005 to constitute an unanalyzed condition in that this path is assumed isolated in the accident analysis.

"The dampers receive a signal to close but are powered from an AC source requiring a Diesel Generator to supply power from a safety related motor control center. The problem occurs when a signal for loss of offsite power is inserted coincident with an SI signal. The dampers start to close, but there was no seal in circuit so that motion to the closed condition would continue once the affected Diesel Generator reenergized the safety related bus and power supply.

"The plant was in Mode 5 at time of discovery, but has operated at power with this configuration since the initial startup of the unit. The dampers could have been closed as evidenced by troubleshooting at the time relying on operator action once the Diesel Generator had reenergized the bus. There is no requirement for Sl and Auxiliary Building isolation in Mode 5. A modification was completed to the circuitry prior to entering Mode 4 where automatic isolation is required.

"The Reportability Evaluation was completed on 5/27/2005 but was not reported within the required 8 hours. The reportability of 8 hours was discovered during review on 06/21/2005 of the completed evaluation. Licensing personnel were immediately contacted."

The licensee notified the NRC Resident Inspector.

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Friday, March 30, 2012