OMAHA, Neb. (AP) — Federal regulators have approved a small change in a Fort Calhoun's flood preparations and they plan to re-examine the worst-case scenario for flooding at the Nebraska nuclear plant.
The Nuclear Regulatory Commission license change issued Wednesday should ensure Fort Calhoun shuts down quickly enough to be protected in a flood. NRC spokeswoman Lara Uselding said the change reflects an issue identified before the 2011 Missouri River flooding and it will make the nuclear plant's flood plan more conservative.
The Omaha Public Power District-owned plant will now shut down whenever the river rises to 1,004 feet above sea level. Previously, the plan didn't require shutdown until the water reached 1,009 feet above sea level.
In 2011, flood waters reached 1,006 feet above sea level and surrounded the nuclear plant on the banks of the Missouri River, which had already been shut down for maintenance and several safety violations. Fort Calhoun's main power plant buildings are at 1,004 feet above sea level.
At the height of the flooding, OPPD erected a network of barriers and set up an assortment of pumps to help protect its buildings. But the plant, 20 miles north of Omaha, remained dry inside.
The concern with flooding is that the water could damage a nuclear plant's equipment and possibly disable its electrical and cooling systems. Without cooling for an extended period, a nuclear plant core could be damaged and harmful radiation might be released.
Fort Calhoun remained shut down from April 2011 until December while officials assessed and repaired flood damage and addressed regulatory violations. OPPD had to deal with a small electrical fire in June 2011, address structural concerns and retrain workers to respond aggressively to safety concerns.
OPPD officials did not immediately respond to questions Wednesday.
Uselding said OPPD has plans in place to protect Fort Calhoun in a flood at least up to 1,014 feet above sea level.
The U.S. Army Corps of Engineers estimates that floodwaters would reach 1,014 feet above sea level if either the Oahe or Fort Randall dams fail at a time when there is already flooding near Fort Calhoun.
But that flood estimate doesn't address what might happen in the unlikely event of the dam closest to the nuclear power plant — Gavin's Point dam on the South Dakota-Nebraska border — failing.
An internal NRC memo examining the flood threat at Fort Calhoun that environmental groups obtained in 2012 said that dam failure upriver from Fort Calhoun could create flooding as high as 1,060 feet above sea level.
NRC officials have said that worst-case scenario report was preliminary. The agency is in the process of reviewing the threat that flooding and other natural disasters present to the nation's nuclear plants. Nebraska's two nuclear plant operators are due to submit a report on the risks to regulators this spring.
The state's other nuclear power plant, Nebraska Public Power District's Cooper station, also sits along the Missouri River, but it faces less risk of flooding because it sits on higher ground next to the river near Brownville, Neb. Cooper nuclear power plant is also about 100 miles downriver from Fort Calhoun.
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NRC page on Fort Calhoun: http://1.usa.gov/GBq2TF
Omaha Public Power District: http://www.oppd.com