The Omaha Public Power District on Monday declared a low-level emergency at its Fort Calhoun Nuclear Station due to rising Missouri River waters.
The U.S. Army Corps of Engineers projects the river level elevation at the plant site is expected to reach 1,004 feet above mean sea level later this week, and is expected to remain above that level for more than one month.
OPPD notified the U.S. Nuclear Regulatory Commission and emergency management agencies in Nebraska and Iowa of the declaration.
Such a "Notification of Unusual Event" is the least-serious of four emergency classifications that are standard in the U.S. nuclear industry, OPPD said in a news release.
Fort Calhoun Nuclear Station will not move out of this emergency classification until it is confident the water will remain below the 1,004-foot level, OPPD said.
Fort Calhoun has been in safe shutdown mode since early April for refueling the plant, and remains in that condition.
In addition to the existing flood-protection at the plant, OPPD employees and contractors have built earth berms and sandbagged around the switchyards and additional buildings on site.
They also are filling water-filled berms around the plant and other major buildings on site, have staged additional diesel fuel inside the protected area and are building additional overhead power lines to provide another option for power for the plant's administration building, training center and one of its warehouses.