Nearly 9 Months after flooding Fort Calhoun deemed unable to mitigate design basis floods

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Last year two American nuclear power plants were threatened by flooding in the Midwest.  The head of the Nuclear Regulatory Commission was dispatched to a nuclear power plant in Fort Calhoun, Neb.,  after flooding Missouri River waters to reach containment buildings and transformers and forcing the shutdown of electrical power.


The Omaha World-Herald ran an article in June of 2011 describing the scene.

Sunday’s event offers even more evidence that the relentlessly rising Missouri River is testing the flood worthiness of an American nuclear power plant like never before. The now-idle plant has become an island. And unlike other plants in the past, Fort Calhoun faces months of flooding.

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Power Reactor Event Number: 47658
Region: 4 State: NE
Unit: [1] [ ] [ ]
RX Type: (1) CE
Notification Date: 02/10/2012
Notification Time: 18:54 [ET]
Event Date: 02/10/2012
Event Time: [CST]
Last Update Date: 02/10/2012
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(ii)(B) – UNANALYZED CONDITION
Person (Organization):
Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
1 N N 0 Cold Shutdown 0 Cold Shutdown
UNANALYZED CONDITION – GUIDANCE NOT ADEQUATE TO MITIGATE A DESIGN BASIS FLOOD”During a review of the station’s procedures for responding to external flooding conditions, it was determined that the guidance is not adequate to mitigate a design basis flood event (1014 feet mean sea level [msl]).”Compensatory actions have been identified and are being implemented. Additional corrective actions are being evaluated.

“The plant is currently in Mode 5, Cold Shutdown, with a river level of 986 feet 2 inches msl with no predictions for river level to pose a threat to safety related components.”

NRC inspectors identified procedural inadequacies relating to the mitigation of flooding. The licensee is addressing the procedural inadequacies.

The NRC Resident Inspector has been notified.

Source: NRC Event Notifications

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