Concern at Nebraska Reactors as Floodwaters Rise
Published: June 26, 2011
BROWNVILLE, Neb. — Like inhabitants of a city preparing for a siege, operators of the nuclear reactor here have spent days working to defend it against the swollen Missouri River at its doorstep. On Sunday, eight days after the river rose high enough to require the operators to declare a low-level emergency, a swarm of plant officials got to show off their preparations to the chairman of the Nuclear Regulatory Commission.
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The reactor, Cooper Station, is one of two nuclear plants on the Missouri River that are threatened by flooding. The second reactor, Fort Calhoun, 85 miles north, came under increased pressure for a brief period on Sunday. Before dawn, a piece of heavy equipment nicked an eight-foot-high, 2,000-foot-long temporary rubber berm, and it deflated. Water also began to approach electrical equipment, which prompted operators to cut themselves off from the grid and start up diesel generators. (It returned to grid power later Sunday.) Both nuclear plants appeared prepared to weather the flooding, their operators and federal government regulators said.
Fort Calhoun was shut down in April for refueling and stayed closed because of predictions of flooding. Plant officials say the facility is designed to remain secure at a river level of up to 1,014 feet above sea level. The water level stabilized at 1,006.5 feet on Sunday, according to the Omaha Public Power District, the operator of the Fort Calhoun plant.
Cooper Station, which is owned by the Nebraska Public Power District, is still running. Managers brought in two tankerloads of extra diesel fuel and have stocked up on all the other consumable materials the plant uses, including hydrogen and carbon dioxide, in case of problems bringing in materials by truck.
At Cooper on Sunday, plant officials led Gregory B. Jaczko, the N.R.C. chairman, on a tour, past thousands of feet of new berms and 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. Mr. Jaczko also toured the building that holds the diesel generators, which would supply vital electricity if the water knocked out the power grid.
Getting into that space required some doing. First, Mr. Jaczko climbed over a makeshift metal staircase to get over the flood barrier at the entrance to the building. Then, past a security guard armed with a military-style rifle, he stepped through a doorway into a small hallway blocked with a four-foot-high flood barrier. Visitors climbed three steps up an A-frame ladder, and then took a long step onto a temporary wooden platform, stepped over the four-foot-high barrier onto another platform, and then down a ladder on the other side.
“And if the water gets in here, what would be the result?” Mr. Jaczko asked.
“We’ve got a sump pump over here,” said Dan Goodman, the assistant operations manager, leading him around to the other side of the giant diesel generator, which is the size of a tractor-trailer.
“One of the things we learned at the Fukushima event is the importance of dealing with natural hazards,” Mr. Jaczko said at a news conference. “Fundamentally, this is a plant that is operating safely.”
Twice an hour, 48 times a day, a technician with a tape measure gauges the water level at the water intake building, and other operators check the level recorded by the Army Corps of Engineers four miles upstream, in Brownville. Plant workers walk the levees near the river and add sandbags where they find soft spots or leaks.
Flooding is always a potential risk for nuclear reactors, but the threat has a higher profile lately because of the tsunami that hit the Fukushima Daiichi reactors in northeastern Japan in March.
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.