"Fukushima was designed by General Electric, as Oyster Creek was around the same time, and the two plants are similar. The problem, he said, was that the hookup is done through electric switching equipment that is in a basement room flooded by the tsunami, he said. “Even though you have generators on site, you have to get the water out of the basement,” he said.
Another nuclear engineer with long experience in reactors of this type, who now works for a government agency, was emphatic. “To completely stop venting, they’re going to have to put some sort of equipment back in service,” he said. He asked not to be named because his agency had not authorized him to speak.
The central problem arises from a series of failures that began after the tsunami. It easily overcame the sea walls surrounding the Fukushima plant. It swamped the diesel generators, which were placed in a low-lying area, apparently because of misplaced confidence that the sea walls would protect them. At 3:41 p.m. Friday, roughly an hour after the quake and just around the time the region would have been struck by the giant waves, the generators shut down. According to Tokyo Electric Power Company, the plant switched to an emergency cooling system that operates on batteries, but these were soon depleted.
Inside the plant, according to industry executives and American experts who received briefings over the weekend, there was deep concern that spent nuclear fuel that was kept in a “cooling pond” inside one of the plants had been exposed and begun letting off potentially deadly gamma radiation. Then water levels inside the reactor cores began to fall. While estimates vary, several officials and industry experts said Sunday that the top four to nine feet of the nuclear fuel in the core and control rods appear to have been exposed to the air — a condition that that can quickly lead to melting, and ultimately to full meltdown.
At 8 p.m., just as Americans were waking up to news of the earthquake, the government declared an emergency, contradicting its earlier reassurances that there were no major problems. But the chief cabinet secretary, Yukio Edano, stressed that there had been no radiation leak.
But one was coming: Workers inside the reactors saw that levels of coolant water were dropping. They did not know how severely. “The gauges that measure the water level don’t appear to be giving accurate readings,” one American official said.
Another nuclear engineer with long experience in reactors of this type, who now works for a government agency, was emphatic. “To completely stop venting, they’re going to have to put some sort of equipment back in service,” he said. He asked not to be named because his agency had not authorized him to speak.
The central problem arises from a series of failures that began after the tsunami. It easily overcame the sea walls surrounding the Fukushima plant. It swamped the diesel generators, which were placed in a low-lying area, apparently because of misplaced confidence that the sea walls would protect them. At 3:41 p.m. Friday, roughly an hour after the quake and just around the time the region would have been struck by the giant waves, the generators shut down. According to Tokyo Electric Power Company, the plant switched to an emergency cooling system that operates on batteries, but these were soon depleted.
Inside the plant, according to industry executives and American experts who received briefings over the weekend, there was deep concern that spent nuclear fuel that was kept in a “cooling pond” inside one of the plants had been exposed and begun letting off potentially deadly gamma radiation. Then water levels inside the reactor cores began to fall. While estimates vary, several officials and industry experts said Sunday that the top four to nine feet of the nuclear fuel in the core and control rods appear to have been exposed to the air — a condition that that can quickly lead to melting, and ultimately to full meltdown.
At 8 p.m., just as Americans were waking up to news of the earthquake, the government declared an emergency, contradicting its earlier reassurances that there were no major problems. But the chief cabinet secretary, Yukio Edano, stressed that there had been no radiation leak.
But one was coming: Workers inside the reactors saw that levels of coolant water were dropping. They did not know how severely. “The gauges that measure the water level don’t appear to be giving accurate readings,” one American official said.
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