Icy conditions have temporarily pulled the plug on power generation at the Fort Calhoun power plant.
The Omaha Public Power District says sub-freezing temperatures caused an ice build-up on one of six sluice gates in the plant's Missouri River water-intake structure.
That build-up was enough to keep the gate from fully closing. All of the gates must be able to close in case of flooding, so this meant the plant had to shut down, even though no flooding is predicted.
The icing was detected Wednesday night. The Nuclear Regulatory Commission was notified of the non-emergency issue and OPPD had the plant off line by Thursday morning.
Workers have since cleared the ice and are taking steps to manually lower the affected sluice gate.
The river water that comes through the intake structure is used to cool and condense steam that has gone through the power turbine. OPPD says it does not get near the water that flows through the reactor.
When the intake structure is operable, workers plan to return the plant to service. Some repairs will be made to the sluice gate before it can operate.