In Japan, fears mount at nuclear reactors

TOKYO

Japan faced the likelihood of a catastrophic nuclear accident this morning, as an explosion at the most crippled of three reactors at the Fukushima Dai-ichi Nuclear Power Station damaged its crucial steel containment structure, emergency workers were withdrawn from the plant and much larger emissions of radioactive materials appeared imminent. • Radiation is spewing from damaged reactors at the crippled nuclear power plant in tsunami-ravaged northeastern Japan in a dramatic escalation of the 4-day-old catastrophe. The prime minister warned residents to stay inside or risk getting radiation sickness.

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

Chief Cabinet Secretary Yukio Edano said a fourth reactor at the complex was on fire and more radiation had been released.

"Now we are talking about levels that can damage human health. These are readings taken near the area where we believe the releases are happening. Far away, the levels should be lower," Edano said.

The sharp deterioration came after government officials said the containment structure of the Unit 2 reactor, the most seriously damaged of three reactors at the Dai-ichi plant, had suffered damage during an explosion this morning.

They initially suggested that the damage was limited and that emergency operations aimed at cooling the nuclear fuel at three stricken reactors with seawater would continue. But the New York Times reported, relying on industry executives, that in fact the situation had spiraled out of control and that all plant workers needed to leave the plant to avoid excessive exposure to radioactive leaks.

If all workers do in fact leave the plant, the nuclear fuel in all three reactors is likely to melt down, which would lead to wholesale releases of radioactive material — by far the largest accident of its kind since the Chernobyl disaster 25 years ago.

Reports of an imminent worsening of the problem came after a frantic day and night of rescue efforts focused largely on the Unit 2 reactor. There, a malfunctioning valve prevented workers from manually venting the containment vessel to release pressure and allow seawater to be injected into it. That meant that the extraordinary remedy emergency workers have been using to keep the nuclear fuel from overheating no longer worked.

As a result, the nuclear fuel in that reactor was exposed for many hours, increasing the risk of a breach of the container vessel and a more dangerous emissions of radioactive particles.

By this morning, the plant's operator, Tokyo Electric Power, said it had fixed the valve and resumed seawater injections, but that they had detected possible leaks in the containment vessel that prevented water from fully covering the fuel rods.

Then the explosion hit the same reactor.

Even if a full meltdown is averted, Japanese officials have been facing unpalatable options. One was to continue flooding the reactors and venting the resulting steam, while hoping that the prevailing winds, which have headed across the Pacific, did not turn south toward Tokyo or west, across northern Japan to the Korean Peninsula. The other was to hope that the worst of the overheating was over and that with the passage of a few more days the nuclear cores would cool enough to essentially entomb the radioactivity inside the plants, which clearly will never be used again. Both approaches carried huge risks.

"It's way past Three Mile Island already," said Frank von Hippel, a physicist and professor at Princeton. "The biggest risk now is that the core really melts down and you have a steam explosion."

The toll of Japan's triple disaster — first an earthquake, then a tsunami, then a related nuclear crisis — is both visceral and hard to see. Coastal town officials say they are running low on body bags; homes and the people inside them have been pulverized.

Four days after the earthquake and resulting tsunami destroyed much of the northeastern coastline here, the U.S. Geological Survey updated the magnitude of the quake from 8.9 to 9.0, making it the fourth-largest in the world since 1900.

So far, more than 500,000 people have been removed from the hardest-hit areas and 15,000 have been rescued. But time was running low for rescuers to help those stranded by flooding or trapped in debris. Officials said about 2,000 bodies were found Monday along the coast of battered Miyagi Prefecture, and a survey of local governments conducted by the Kyodo news agency found that about 30,000 people in the devastated areas remain unaccounted for.

The death toll from last week's earthquake and tsunami jumped today as police confirmed the number killed had topped 2,400, though that grim news was overshadowed by a deepening nuclear crisis. Officials have said previously that at least 10,000 people may have died in Miyagi province alone.

Japan wrestled to regain control of ultra-hot fuel rods in three nuclear reactors at the Fukushima plant.

Tokyo Electric, which over the weekend said it had 1,400 people working at the complex, said it was evacuating all nonessential personnel, leaving about 50.

The string of earthquake- and tsunami-triggered troubles at the Fukushima Dai-ichi plant began last Friday when a loss of grid power (because of the earthquake) followed by a loss of backup diesel generators (because of the tsunami) led to the failure of cooling systems needed to keep reactor cores from overheating.

Although government officials say that radiation levels around the plant are not dangerous, several thousand people have been tested for exposure. On Monday, the U.S. 7th Fleet repositioned its ships about 100 miles away from the nuclear plant after 17 crew members were found to have trace amounts of radioactive material on their bodies and clothing.

The International Atomic Energy Agency said Japan has distributed 230,000 units of stable iodine to evacuation centers. The iodine has not been administered to residents; the distribution is a precautionary measure.

The ingestion of stable iodine can help prevent the accumulation of radioactive iodine in the thyroid.

Information from the New York Times, Associated Press and Washington Post was used in this report.

In Japan, fears mount at nuclear reactors 03/15/11 [Last modified: Tuesday, March 15, 2011 12:34am]

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