"This was an additional, a secondary, level of protection that we had put up," OPPD spokesman Mike Jones told CNN. "The plant remains protected to the level it would have been if the aqua berm had not been added."
The plant remained under an unusual event declaration, the lowest of the Nuclear Regulatory Commission's four-tiered emergency classification system. The plant's 500-megawatt Combustion Engineering pressurized water reactor has been out of operation since refueling in April. Downstream, the power district's Cooper nuclear plant also remains under an usual event declaration and is still operating.
River levels at Fort Calhoun recently stood at 1,006 feet above sea level and are not expected to exceed 1,008 feet above sea level – six feet below the maximum flood level anticipated in the plant's design. A number of flood control measures have been taken at both plants, including sandbag barriers and extra diesel shipments for emergency generators.
On Sunday, Nuclear Regulatory Commission Chairman Gregory Jaczko visited the Cooper plant and reiterated that it was operating safely. He plans to visit Fort Calhoun today.