|Tuesday, July 12, 2011 3:00 pmThe plant, about three miles south of Brownville along the Missouri River, was threatened by floodwaters.
As required by federal regulations, NPPD and Cooper management declared a "notification of unusual event" on June 19 due to the steady rise of the river.
A notification of unusual event is the lowest and least serious of four emergency classifications established by the U.S. Nuclear Regulatory Commission for nuclear power plants.
At 9:47 a.m. Tuesday, the plant exited that emergency status because river water levels near Cooper had dropped to 895.8 feet above sea level, which is more than three feet below the average sea level at which Cooper is required to enter the emergency classification status, NPPD said in a news release.
Weather forecasts and expected upstream dam releases indicate the river's level at Brownville will slowly continue to drop, the Columbus-based utility said. The plant continues to operate safely.
The nuclear plant issued a notification of unusual event as part of its emergency preparedness plan that includes procedures to follow when flooding conditions are in effect.
Cooper was in such status for about 23 days. NPPD officials said there was no threat to plant employees or the public throughout the event.
Utility officials made the decision after several days of river elevations measuring consistently below the 899-foot mark and discussing the decision with county and state agencies.
Plant staff also conducted an assessment of the site's emergency preparedness plan and made a decision to keep a majority of the flood barricades in place, while removing selected others for accessibility in and around the plant.
Fort Calhoun Station, the state's second nuclear power plant about 20 miles north of Omaha along the Missouri River, remains at emergency status.
Omaha Public Power District management declared a notification of unusual event on June 6 when floodwaters were projected to reach 1,004 feet above sea level. It reached that level three days later.
Fort Calhoun Station is protected to a river level of 1,014 feet.
OPPD has said it will not not start generating electricity until floodwaters surrounding Fort Calhoun Station recede. It was shut down in April for a scheduled refueling outage.
