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Event Notification Report for April 20, 2010

U.S. Nuclear Regulatory Commission
Operations Center

Event Reports For
04/19/2010 - 04/20/2010

** EVENT NUMBERS **


45855 45856

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Power Reactor Event Number: 45855
Facility: PRAIRIE ISLAND
Region: 3 State: MN
Unit: [1] [ ] [ ]
RX Type: [1] W-2-LP,[2] W-2-LP
NRC Notified By: JOHN KEMPKES
HQ OPS Officer: DONALD NORWOOD
Notification Date: 04/19/2010
Notification Time: 03:12 [ET]
Event Date: 04/18/2010
Event Time: 22:25 [CDT]
Last Update Date: 04/19/2010
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(ii)(B) - UNANALYZED CONDITION
50.72(b)(3)(v)(A) - POT UNABLE TO SAFE SD
50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Person (Organization):
STEVE ORTH (R3DO)

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

LCO 3.0.3 ENTRY AND LOSS OF SAFETY FUNCTION DUE TO LOSS OF TURBINE BUILDING HIGH ENERGY LINE BREAK COMPENSATORY MEASURE

"At 2225 CDT on 4/18/2010, Operations discovered that the Unit 1 Turbine Building Truck Aisle Rollup Door Security Fence was closed. This fence was to be maintained open as the truck aisle is a required drainage path from the Unit 1 Turbine Building to outside in the event of flooding resulting from a High Energy Line Break (HELB). With the expanded metal mesh door [fence] closed, turbine building debris could clog the drainage path and result in a higher than calculated water level being reached for this event. As the final water level cannot be predicted, this represented an unanalyzed condition. The higher water levels would be reached at least one hour after the postulated turbine building HELB event. High water levels could result in a Loss of Safety Function for Unit 1 Emergency Diesel Generators. Auxiliary Feedwater (both units) and DC Electrical Power (both units) if water levels exceed critical heights in the associated rooms.

"The doors [fence] were reopened at 2227 CDT. Unit 1 entered LCO 3.0.3 for this two minute period. With the doors [fence] opened, Unit 1 and 2 LCO conditions were again satisfied.

"The Unit 2 truck aisle was in the assumed condition, and Unit 2 is in Mode 5 so loss of AFW or DC power would not result in an LCO 3.0.3 entry. Unit 2 Emergency Diesel Generators are not affected as the Unit 2 truck aisle drain path would prevent water levels from reaching critical heights.

"The initial investigation determined that a Security Officer had closed the gate at approximately 1855 CDT on 4/18/2010.

"The NRC Resident Inspector has been notified. A press release is not planned."

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Power Reactor Event Number: 45856
Facility: COOPER
Region: 4 State: NE
Unit: [1] [ ] [ ]
RX Type: [1] GE-4
NRC Notified By: JOHN MYERS
HQ OPS Officer: STEVE SANDIN
Notification Date: 04/19/2010
Notification Time: 06:20 [ET]
Event Date: 04/19/2010
Event Time: 01:58 [CDT]
Last Update Date: 04/19/2010
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(xiii) - LOSS COMM/ASMT/RESPONSE
Person (Organization):
BLAIR SPITZBERG (R4DO)

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

TSC EMERGENCY VENTILATION SYSTEM DISCOVERED NON-FUNCTIONAL WHILE PLACING A CLEARANCE

"At 0158 [CDT] on 4/19/2010, during implementation of clearance order activities, it was identified that the Technical Support Center (TSC) ventilation system would not transition to the emergency mode of operation. This condition is reportable under 10CFR50.72(b)(3)(xiii).

"The TSC ventilation system consists of normal ventilation equipment, including a normal air supply unit OAF-1, and an emergency air supply unit OAF-2 which provides conditioned air with HEPA and charcoal filtration. The system is placed in the emergency mode as follows:

"When TSC HEPA FILTER BYPASS switch is placed to EMER UP, the Energy Management System (EMS) receives an emergency signal and the following actions occur:

1. Air Dampers AD1443 and AD1445 close and cause OAF-1 to stop.
2. Air Dampers AD1442 and AD1444 open and cause OAF-2 to start.
3. Outside air to the TSC is routed through HEPA filter unit.

"During the clearance order activities, the TSC HEPA FILTER BYPASS switch was placed to EMER UP, but the actions above did not occur. A second attempt was made to place the system in the emergency mode, without success. Based upon these indications, it is considered that the TSC ventilation cannot be placed in the emergency mode. This is reportable under 10CFR50.72(b)(3)(xiii) as an event that results in a major loss of emergency assessment capability due to the loss of the emergency response facility. Per Emergency Plan Implementing Procedure 5.7.7 for Activation of TSC, personnel can relocate to the Alternate TSC (control room) and Alternate Operations Support Center (OSC) where the TSC functions will be performed. Both of these alternate facilities are equipped with emergency ventilation systems and are currently fully functional.

"Troubleshooting of the TSC ventilation system discrepancy will commence today."

This system was last tested successfully on 10/20/2008 and due for retest on 6/21/2010.

The licensee will inform the NRC Resident Inspector.

Page Last Reviewed/Updated Thursday, March 29, 2012
Thursday, March 29, 2012