Japan nuclear crisis eclipses Three Mile Island, nears 'Chernobyl league'
Fifty workers and fire hoses are all that remain at Japan's Fukushima I plant to cool three hot reactors and six pools containing spent fuel rods – perhaps for months to come.
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The head of France's Nuclear Safety Authority, Andre-Claude Lacoste, also characterized the situation in Japan as still less serious than the Chernobyl disaster but worse than the partial core meltdown at Three Mile Island in Pennsylvania. "We are now in a situation that is different from yesterday's. It is very clear that we are at a Level Six," the ASN president said at a news conference in Paris.Skip to next paragraph
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Systems at the plant no longer provide any cooling function, say Japanese authorities. All of the cooling for the three endangered reactors (three others are in cold shutdown) and six spent-fuel pools is from fire hoses. Teams have been alternately venting radioactive steam and then injecting water into each reactor in a bid to cool it down.
At the current rate, the cooling of the reactors must continue for weeks, Dr. von Hippel and others agree. If rising radioactivity at the site or mechanical failure prevents these workers from continuing to cool the reactors steadily, meltdown becomes likely.
The good news so far is that most of the cesium 137 and iodine 131 – dangerous radioactive isotopes from each of the reactors – have been captured in "suppression pools," a type of filtering system beneath each reactor, von Hippel says.
The bad news is that if just one reactor core melts, it is likely to melt through the steel containment vessel and could easily drop into this highly radioactive pool of water. That could cause either an explosion or a rapid vaporization, releasing all the highly radioactive elements to go with the wind, says von Hippel. At two reactors, the secondary containment systems – the concrete buildings surrounding the reactors – were destroyed in earlier explosions.
Cesium 137 blowing on the wind made the area around the Chernobyl site, equivalent to half the size of New Jersey, from being inhabitable, even today.
Von Hippel and Dr. Lyman both say a critical issue is keeping water from boiling off in the six spent-fuel pools. A fire at the spent-fuel pool for the plant's No. 4 reactor was extinguished Monday, but radiation spiked afterward.
Though water is evaporating from these pools more slowly than from around the reactors, long-term damage from the Fukushima crisis may hang less on the reactors and more on whether the spent-fuel pools remain intact.
Temperatures in the No. 5 and No. 6 spent-fuel pools seemed to be rising, Yukio Edano, chief cabinet secretary and government spokesman, said in a press conference on Tuesday. While water in these large pools is unlikely to evaporate completely soon, workers are finding it hard to reach them because the water is so hot, a spokesman for Japan's Nuclear and Industrial Safety Agency, which oversees nuclear plants, told The New York Times.
"Where the fire took place in the No. 4 pool, there is essentially a whole core's worth of fuel," says Lyman. "The problem is, they can't rule out whether it's boiling right now. There just hasn't been any conclusive information. But they have to keep these pools covered – and at the same time keep the reactors cool."
In the meantime, emergency workers may have to vent the reactors and pour in water "for weeks and weeks," he says. "I hope they can sustain that."