The Nebraska Public Power District issued a flooding alert Sunday for its nuclear power plant as the Missouri River continues to rise in southeast Nebraska and northwest Missouri.
Mark Becker, a spokesman for the Columbus-based utility, said the "notification of unusual event" sent to the Nuclear Regulatory Commission was expected as the river swells above record levels. The declaration is the least serious of four emergency notifications established by the federal commission.
"We knew the river was going to rise for some time," Becker said. "It was just a matter of when."
The plant was operating Sunday at full capacity, and there was no threat to plant employees or to the public, he said.
The notification was issued about 4 a.m. Sunday, when the river reached 42.5 feet, or 899 feet above sea level, at the Cooper Nuclear Station near Brownville, which is across the river from Atchison County, Mo. Cooper is at 903 feet elevation, and NPPD officials said the river would have to climb to 902 feet at Brownville before officials would shut down the plant.
Becker said the river is expected to crest there at a little over 900 feet. At such a level, officials would need to barricade internal doorways at the plant to protect equipment.
The plant has been preparing for the flooding since May 30. More than 5,000 tons of sand have been brought in to construct barricades around it and access roads, according to NPPD. Becker said workers will continue to monitor the flood protection to ensure it's holding up against the swollen river.
"It seems to be doing pretty well," he said.
The corps said Sunday that the river level at Brownville had surged about 2 feet from Saturday morning to Sunday morning and continued to rise. Col. Bob Ruch attributed that to heavy rain on the Nishnabotna River, which flows into the Missouri River, and to some erosion along a levee upstream at Hamburg, Iowa, that created a water pulse.
Water was flowing over a levee near Brownville and into farmland but the levee was being built up to alleviate that, said Jodi Fawl, spokeswoman for the Nebraska Emergency Management Agency.
Nemaha County emergency manager Renee Critser said that as workers were building up one section of the levee Sunday to alleviate the overtopping between Brownville and Nemaha, water would flow over in another spot. Workers continued Sunday afternoon to add sandbags along the levee to keep the water at bay.
"It's nothing major," Critser said.
The Cooper Nuclear Station is one of two plants along the Missouri River in eastern Nebraska. The Fort Calhoun Station, operated by the Omaha Public Power District, is about 20 miles north of Omaha. It issued a similar alert June 6.
The river has risen at least 1.5 feet higher than Fort Calhoun's 1,004-foot elevation above sea level. The plant can handle water up to 1,014 feet, according to OPPD. The water is being held back by a series of protective barriers, including an 8-foot rubber wall outside the reactor building.
Flooding remains a concern all along the river because of the massive amounts of water released by the Army Corps of Engineers from upstream reservoirs. The river is expected to rise as much as 5 to 7 feet above flood stage in much of Nebraska and Iowa and as much as 10 feet over flood stage in parts of Missouri.
The corps expects the river to remain high at least into August because of heavy spring rains in the upper Plains and substantial Rocky Mountain snowpack melting into the river basin.
NPPD's flood page: http://www.nppd.com/flood/