– Nuclear Plant’s Vital Equipment Dry, Officials Say (New York Times, June 27, 2011):
FORT CALHOUN, Neb. — When safety regulators arrive for a tour of a nuclear plant, the operators usually give the visitors a helmet, safety glasses and earplugs. When Gregory B. Jaczko, chairman of the Nuclear Regulatory Commission, got to the Fort Calhoun plant on Monday morning, the Omaha Public Power District offered him a life jacket.
Technically, what the plant is undergoing is not a flood but a “water event,” as the regulatory commission classifies it. But Fort Calhoun has clearly been outflanked by the Missouri River, first at its front door and now at its back door as well. The only access route to the plant is over a sinuous path of catwalks built over the submerged parking lot and walkways in recent weeks.
Vital equipment like generators, pumps and controls are dry, according to the power company and to Mr. Jaczko, who spent a couple of hours clambering over walls of sandbags and inspecting waterproof barriers, some of which were added in recent months at the commission’s insistence.
In the control room, the commission chairman stopped to look at a display that said, in huge numerals, “1006.46,” referring to how far in feet the Missouri stands above sea level. Another display, in red, showed a squiggly history of the river’s rise.
The Army Corps of Engineers and other experts say the plant is safe for up to 1,014 feet above sea level, which is higher than they expect the water to get. Despite the alarming sight of a plant surrounded by sandbag walls and a dozen pumps sucking in and spitting out water, Mr. Jaczko said later at a news conference that the operators had the situation in hand.
Among the more striking scenery at this plant a few miles north of Omaha was the floating carcass of a 2,000-foot-long rubber berm that was supposed to help protect the plant. A plant worker driving a small earth mover called a Bobcat accidentally sideswiped it early Sunday morning, pulling it open like a zipper.
“That was a huge morale dump for us,” said the plant’s manager, Timothy Nellenbach. But the barrier was not required by the regulatory commission’s rules, and its chief purpose was solely to keep water away from the barriers that the safety agency does require, he said.
N.R.C. inspectors agreed. “Sometimes visually you’ll see things at the site, see changes at the site, but those don’t always have an impact on the safety aspect of facilities,” Mr. Jaczko said at the news conference.
The chairman’s tour, after a stop on Sunday at another nuclear plant threatened by the flooding, was partly an effort to reassure the public. In a room at the Fort Calhoun plant crammed with television monitors showing vital equipment in radioactive areas, Mr. Nellenbach showed safety pumps that are in the basement but remain dry. So is the plant’s pool of radioactive spent fuel, which is at 1,035.5 feet above sea level.
“There are Internet reports that river water had risen to the level of the spent fuel pool, but that is obviously impossible,” Mr. Nellenbach said.
If all cooling of the plant’s nuclear fuel ceased — considered an unlikely prospect because the plant is connected to the power grid and has also shown that it can also operate its emergency diesel generators — water would begin boiling in the nuclear reactor after 36 hours, plant officials said. Yet it would take weeks for the water to fall to a level at which the reactor core would be damaged, they added.
The spent fuel pool would begin to boil in 80 hours. In both cases, the solution would be to pour in more water, and diverse pumps are available for that job, plant officials said. The plant has been shut since early April, and heat production in the core is down to half a megawatt, compared with 1,500 megawatts when the plant is running normally, they said.
If the plant did lose outside power, “it would be nothing like Fukushima, where they lost all of their infrastructure,” Mr. Nellenbach declared. At the Fukushima plant in Japan, an earthquake set off a tsunami that wiped out the diesel generators, and the quake itself shut off the grid and key electrical switches.
– Even In Shutdown Mode Fort Calhoun Nuclear Plant Requires Electricity To Avoid Melting Of The Core
At Fort Calhoun, where the river has risen gradually, the water seeps in through sandbag walls, electrical conduits and other places that workers had not thought much about before. There are so many small water pumps running to keep up with the leaks that keeping them supplied with gasoline and diesel requires something akin to a bucket brigade.
Orange plastic fuel cans are rolled on a cart over the catwalks and then handed off to employees who are headed deeper into the plant. Climbing over the sandbags at the entrances, they carry them in, and workers on their way out pick up a few empties and carry them out for refilling.
As the river still flows silently past, at perhaps 15 miles an hour instead of the normal 7 or 8, the drone of pumps is punctuated by the trill of birdsong. Birds seem more plentiful, some say, because of the bumper crop of mosquitoes that the flooding has produced. Speed-limit signs in the neighborhood poke out of enormous ponds of water, and there are so many “Road Closed” signs that it is a wonder that Nebraska has not run out of them.
“We’ve had water at nuclear plants before, but this is the only time we can recall it to this extent or duration,” said Jeffrey Clark, a Nuclear Regulatory Commission staff member from the regional office in Arlington, Tex., who arrived here on June 9 for a quick look around but then stayed on.
The river is not expected to get substantially higher, but it may not get lower anytime soon, either. On Monday morning, Mr. Jaczko met with the Army Corps of Engineers but did not get a great deal of encouragement.
“We don’t like to give worst-case scenarios anymore because every time it rains, we get a new worst case,” said Col. Robert J. Ruch, commander of the Omaha District.