Blast, radiation leak at Japanese nuclear plant

TOKYO, March 12,2011: Japanese authorities confirmed Saturday that radiation had leaked from a quake-hit nuclear plant after an explosion rocked the site.

The blast at the Fukushima Daiichi nuclear facility occurred just hours after officials said they feared a reactor could melt down.

Footage on Japanese TV showed that the walls of one building had crumbled, leaving only a skeletal metal frame standing. Plumes of smoke were spewing out of the plant.

It was not clear if the damaged building housed the reactor.
Several workers were injured by the blast at Fukushima Unit 1, Japanese TV station NHK reported.

The hourly amount of radiation leaking from Fukushima was equal to the amount permitted in one year, an official told the Kyodo news agency.

Area residents were told to stay indoors, not to drink tap water and to cover their faces with masks or wet towels, Britain's Sky News reported.

"We are now trying to analyze what is behind the explosion," government spokesman Yukio Edano said, stressing that people should quickly evacuate a six-mile radius. "We ask everyone to take action to secure safety."

Authorities had warned Friday of a failure of a cooling system resulting from a powerful earthquake and tsunami.

'Radioactive vapors'
Pressure had been building up in the reactor and Japan's Nuclear and Industrial Safety Agency told reporters Saturday that it was venting "radioactive vapors" to relieve that pressure. Officials said they were measuring radiation levels in the area.

Before the blast, the reactor in trouble had already leaked radiation: Operators at the Fukushima Daiichi plant's Unit 1 detected eight times the normal radiation levels outside the facility and 1,000 times normal inside Unit 1's control room.
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Two reactors had lost cooling ability and a meltdown was possible at one of the reactors because of the overheating, said Ryohei Shiomi, an official with Japan's nuclear safety commission.

Speaking before the explosion, he said that ven if there was a meltdown, it wouldn't affect people outside a six-mile radius. Most of the 51,000 residents living within the danger area had been evacuated, Shiomi added.
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Jiji news agency quoted nuclear authorities as saying that there was a high possibility that nuclear fuel rods at No. 1 reactor may be melting or have melted.

Experts said earlier that if that is the case, it means the reactor is heating up. If that is not halted, such as by venting steam which releases small amounts of radiation, there is a chance it would result in a rupture of the reactor pressure vessel.

But the risk of contamination can be minimized as long as the external container structure is intact, they said. The worry then becomes whether the quake has weakened the structure.

There has been no official word so far on whether the structure was damaged by the quake.
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The 8.9 magnitude quake and the tsunami that followed cut off electricity to the site and disabled emergency generators, knocking out the main cooling system.

'No Chernobyl is possible'
The Tokyo Electric Power Co. (TEPCO), which operates the six-reactor Daiichi site, said Friday that it had also lost cooling ability at a second reactor there and three units at its nearby Fukushima Daini site.

The government declared state of emergency at all those units.

Prior to the blast, Japanese officials and experts were at pains to say that while there would be radiation leaks, they would be very small and have dismissed suggestions of a repeat of a Chernobyl-type disaster.
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"No Chernobyl is possible at a light water reactor. Loss of coolant means a temperature rise, but it also will stop the reaction," said Naoto Sekimura, a professor at the University of Tokyo.

"Even in the worst-case scenario, that would mean some radioactive leakage and equipment damage, but not an explosion. If venting is done carefully, there will be little leakage. Certainly not beyond the 3-km (1.8-mile) radius."

Edwin Lyman, a senior scientist with the Union of Concerned Scientists, which opposes nuclear energy, told msnbc.com Friday that TEPCO was facing a potential catastrophe.

"It's just as bad as it sounds," he said. "What they have not been able to do is restore cooling of the radioactive core to prevent overheating and that's causing a variety of problems, including a rise in temperature and pressure with the containment (buildings).

Source : NBC, msnbc.com and news services