the nuclear crisis

Japan's nuclear crisis deepens as third reactor loses cooling capacity

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By Steven Mufson and Chico Harlan
Tuesday, March 15, 2011

Japan's nuclear emergency turned more dire on Tuesday after the third explosion in four days rocked the seaside Fukushima Daiichi complex and fire briefly raged in a storage facility for spent fuel rods at a fourth, previously unaffected reactor.

Officials from Tokyo Electric Power Co., owner of the nuclear complex, said radioactive substances were emitted after a 6:14 a.m. explosion, which took place in the unit 2 reactor. The blast took place near or in the suppression pool, which traps and cools radioactive elements from the containment vessel, officials said. The explosion appeared to have damaged valves and pipes, possibly creating a path for radioactive materials to escape.

Prime Minister Naoto Kan told the nation Tuesday morning that radiation had already spread from the reactors and there was "still a very high risk of further radioactive material escaping." He advised people within 19 miles of the plant to remain indoors. He urged calm.

Tokyo Electric, which over the weekend said it had 1,400 people working at the complex, said it was evacuating all but 50 workers. Kan hailed those workers, who he said "are putting themselves in a very dangerous situation."

The setbacks came as Tokyo Electric was still wrestling to regain control of ultra-hot fuel rods in two other nuclear units, nos. 1 and 3, by flooding them with seawater.

Tuesday began with a fire that broke out in a pool storing spent fuel rods at the base of unit 4, which had been shut down for inspection before last Friday's earthquake. Radioactive substances might have spewed outside from the fire, officials said, because the structure housing the pool was damaged by Monday's explosion at unit 3.

Half an hour later, the explosion at unit 2 took place. Experts said that, unlike the two previous explosions that destroyed outer buildings, this explosion might have damaged portions of the containment vessel designed to bottle up radioactive materials in the event of an emergency.

The explosion - more serious than the earlier ones - was followed by a brief drop in pressure in the vessel and a spike in radioactivity outside the reactor to levels more than eight times what people ordinarily receive in a year, the company said.

The new setbacks came on the heels of a difficult Monday at Fukushima Daiichi unit 2, one of six reactors at the site. Utility officials there reported that four out of five water pumps being used to flood the reactor had failed and that the other pump had briefly stopped working. As a result, the company said, the fuel rods, normally covered by water, were completely exposed for 140 minutes.

That could have grave consequences, worsening the partial meltdown that most experts think is underway. By comparison, in the 1979 Three Mile Island, Pa., nuclear plant accident, it took just two hours for half the plant's nuclear fuel to melt.

According to a report by the Kyodo news agency, the fifth pump was later restarted, and seawater mixed with boron was again injected in a desperate bid to cool the reactor, but the fuel rods remained partially exposed and ultra-hot. On Tuesday morning, Tokyo Electric said that 2.7 meters, or less than half, of the rods were still exposed.

The other four pumps were thought to have been damaged by a blast Monday that destroyed a building at the nearby unit 3 reactor, Kyodo reported. That blast, like one on Saturday at unit 1, was caused by a buildup in hydrogen generated by a reaction that took place when the zirconium alloy wrapped around the fuel rods was exposed to steam at 2,200 degrees Fahrenheit.


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