FORT CALHOUN, Neb. — The Omaha Public Power District is reinstalling the plastic, water-filled dam that — until bursting — had kept Missouri River floodwaters away from the buildings that house its nuclear reactor.
After the Aqua Dam ruptured on June 26, water flowed around the Fort Calhoun Nuclear Station to a depth of more than 2 feet.
However, OPPD officials said, the water did not reach the reactor or other critical areas because additional barriers, including sandbags, were in place.
Mike Jones, a spokesman for the utility, said Wednesday that the Aqua Dam is expected to be in place by Saturday.
The utility has not experienced any significant difficulties in reinstalling the barrier, he said. If completed by Saturday, it will have been out of commission about two weeks.
When in place, the Aqua Dam gives employees room to walk around outside of the reactor buildings, making it easier to work.
The 16-foot-wide, 8-foot-tall Aqua Dam is made of an industrial plastic fabric and has been used in other parts of the United States and Canada to protect highways, businesses and homes, said Matthew Wennerholm, a salesman for Aqua Dam Inc.
Jones said the Aqua Dam ruptured after an employee driving a Bobcat loader brushed a wheel up against it. Employees have worked around the clock to protect the plant, and this accident took place at 1:25 a.m. on a Sunday.
The Fort Calhoun reactor, located about 20 miles north of Omaha, had been shut down for maintenance in early April and has remained idle because of the flooding.
Both OPPD and the Nuclear Regulatory Commission say loss of the Aqua Dam has not affected the safety of nuclear materials at the plant.
OPPD disconnected the plant from the nation's electrical grid for about 12 hours on June 26, the day of the rupture, because water also leaked through barriers protecting the plant's tranformers. During that time, nuclear safety equipment was powered by backup diesel generators.
After pumping water away from the transformers and verifying that they weren't damaged, OPPD reconnected to the electrical grid that same day.
Gregory Jaczko, Nuclear Regulatory Commission chairman, said during a recent visit to Omaha that he wasn't surprised by the Aqua Dam's failure. Because the barrier is not part of the NRC's required protections for nuclear plants, its durability hadn't been vetted by the agency, he said.
Today, OPPD said, the Missouri River level at Fort Calhoun was at 1,006 feet above sea level.
The Army Corps of Engineers has forecast that the river could reasonably be expected to crest at 1,008 feet above sea level at Fort Calhoun this summer.
The Aqua Dam would be considered protective to 1,010 feet, Jones said. Federally mandated protections are in place to keep the plant safe to 1,014 feet, and additional backup systems should kick into gear should water get higher, OPPD and NRC officials say.
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