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Event Notification Report for January 26, 2007

U.S. Nuclear Regulatory Commission
Operations Center

Event Reports For
01/25/2007 - 01/26/2007

** EVENT NUMBERS **


43119 43121

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Power Reactor Event Number: 43119
Facility: WOLF CREEK
Region: 4 State: KS
Unit: [1] [ ] [ ]
RX Type: [1] W-4-LP
NRC Notified By: LANCE LANE
HQ OPS Officer: JOHN MacKINNON
Notification Date: 01/25/2007
Notification Time: 15:38 [ET]
Event Date: 01/25/2007
Event Time: 05:42 [CST]
Last Update Date: 01/25/2007
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(xiii) - LOSS COMM/ASMT/RESPONSE
Person (Organization):
MICHAEL HAY (R4)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
1 N Y 100 Power Operation 100 Power Operation

Event Text

LOSS OF SAFETY PARAMETERS DISPLAY SYSTEM (SPDS)


"On 01/25/07 at 05:42am CT, the Wolf Creek Generating Station Nuclear Plant Information System (NPIS) computer 'C' primary and all backup MUX's failed. Subsequent troubleshooting failed to restore all primary MUX's to operation in a short period of time.

"The failure to restore the NPIS computer has resulted in a loss of functionality of the SPDS. Due to SPDS being lost for longer than a short period of time, Wolf Creek Nuclear Operating Corporation is making this ENS notification pursuant to the criteria of 10 CFR 50.72(b)(3)(xiii). There was no other loss of emergency assessment capability concurrent with the ongoing loss of SPDS. Plant personnel entered the appropriate Off-Normal procedure and obtained local readings for the equipment that is normally monitored by SPDS and NPIS during the loss of the plant computer.

"NPIS was restored to service and declared operable on the primary plant computer at 13:57 CT. The return of the NPIS computer to an operable condition restored the SPDS assessment capability function.


"The licensee notified the NRC Resident Inspector"

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Power Reactor Event Number: 43121
Facility: ARKANSAS NUCLEAR
Region: 4 State: AR
Unit: [ ] [2] [ ]
RX Type: [1] B&W-L-LP,[2] CE
NRC Notified By: JAMES CRABILL
HQ OPS Officer: JOHN MacKINNON
Notification Date: 01/25/2007
Notification Time: 20:11 [ET]
Event Date: 01/25/2007
Event Time: 17:17 [CST]
Last Update Date: 01/25/2007
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(i) - PLANT S/D REQD BY TS
Person (Organization):
MICHAEL HAY (R4)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
2 M/R Y 45 Power Operation 0 Hot Standby

Event Text

TECHNICAL SPECIFICATION SHUTDOWN DUE TO DROPPED CONTROL ELEMENT ASSEMBLY (CEA)


"Notification of shutdown required by the Technical Specifications per 10CFR50.72(b)(2)(i). Arkansas Nuclear One Unit 2 is shut down in Mode 3 (Hot Standby) due to Control Element Assembly misalignment as required by Technical Specification 3.1.3.1.d (All CEAs shall be OPERABLE with each CEA of a given group positioned within 7 inches, indicated position, of all other CEAs in its group). CEA #35 dropped to the bottom of the core due to power supply breaker trip during maintenance and was unable to be recovered within the allowed time. All rods were verified to trip normally as part of the controlled shutdown."

The reactor was manually tripped from approx. 20% power. The reactor trip was preplanned.

The NRC Resident Inspector and the county were notified of this event by the licensee. Licensee will also notify the State of this event.

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Thursday, March 29, 2012