More than 2 feet of water has flooded around containment buildings and electrical transformers at a 478-megawatt nuclear plant 20 miles north of Omaha Nebraska. The Nuclear Regulatory Commission (NRC) said the breach in the 2,000-foot inflatable berm around the Fort Calhoun station occurred around 1:25 a.m. local time. Reuters:
"Reactor shutdown cooling and spent-fuel pool cooling were unaffected, the NRC said. The plant, operated by the Omaha Public Power District, has been off line since April for refueling.
Crews activated emergency diesel generators after the breach, but restored normal electrical power by Sunday afternoon, the NRC said.
Buildings at the Fort Calhoun plant are watertight, the agency said. It noted that the cause of the berm breach is under investigation."
Luckily Fort Calhoun has been inactive since April but its fellow nuclear plant along the Missouri River, Cooper Station, remains running. NRC visited the site Sunday as the facility has been closely watched as Missouri River waters continue to rise from heavy rains and snow melt. NY Times:
"At Cooper on Sunday, plant officials led Gregory Jaczko, the N.R.C. chairman, past thousands of feet of new berms that would hold back the river if it overtopped the levees, past buildings where every doorway was barricaded with four-foot high water barriers that are intended to survive even if an earthquake hits during a flood, and into the building that holds the diesel generators, which would supply vital electricity if the water knocked out the power grid."
"Flooding is always a potential problem for nuclear reactors, but the threat has a higher profile lately because of the tsunami that hit the Fukushima Daiichi reactors in northeastern Japan on March 11. Nuclear reactors require electric power to pump cooling water even when they are shut down, and at Fukushima, the tsunami destroyed the connection to the electric grid, flooded the emergency diesel generators, washed away the extra tanks of diesel fuel and damaged the switches that would have controlled the flow of electricity from the emergency generators to pumps, valves and other vital equipment.
Unlike a tsunami, the challenges posed by the Missouri River was obvious for days in advance. At Cooper, the plant’s license specifies that it would have to shut down if the river reached 902 feet above sea level, and it came close, but then a levee on the Missouri side broke on Thursday night, and the water level fell precipitously."
To make matters more uncomfortable the trip comes at a time when N.R.C Chairman Jaczko is being heavily criticized by House Republicans and his own agency's inspector general for decisions he made about Yucca Mountain, the proposed nuclear wast repository. On June 24, four long-time members of the Commission staff complained in testimony to a House subcommittee that much of their work had been discarded when Mr. Jaczko suddenly ordered the staff to drop work on evaluating whether the Yucca project should get a license. The inspector general found that Mr. Jaczko was "not forthcoming" with the other four commissioners about what he was doing when making the Yucca project order.