Radiation rising beyond exclusion zone

Sackiko Sakamaki, Jonathan Tyrone – Sidney Morning Herald April 1, 2011

Pressure is growing on Japan to expand the 20-kilometre exclusion zone around Fukushima after the International Atomic Energy Agency said radiation in one village 40 kilometres away had reached evacuation level.

However, Japan said it had no immediate plans to widen the zone around the stricken nuclear plant.

Many countries have told their citizens in Japan to respect an 80-kilometre exclusion zone.

”We have advised [Japan] to carefully assess the situation,” Denis Flory, the agency’s deputy director-general, said.

The station operator, Tepco, said that iodine-131 in the sea near the plant had risen to a new high of 4385 times the legal level.

Meanwhile, the Prime Minister, Naoto Kan, said the nuclear plant must be scrapped entirely.

He told the Japanese Communist Party leader Kazuo Shii that the whole of the crippled Fukushima Daiichi power station should be decommissioned, Kyodo News reported.

Japan has been considering pouring concrete into the plant, and the United Nation’s nuclear watchdog agency has warned that a potential uncontrolled chain reaction could cause further radiation leaks.

The chief cabinet secretary, Yukio Edano, ruled out yesterday that the two undamaged reactors at the six-unit plant would be salvaged. Units 1 to 4 suffered from hydrogen explosions, presumed meltdowns and corrosion from seawater sprayed on radioactive fuel rods after the earthquake and tsunami three weeks ago cut power to reactor cooling systems.

Workers have averted a total meltdown by injecting water into the damaged reactors for the past two weeks. The complex’s six units are connected with the power grid and two are using temporary motor-driven pumps. Work to repair monitoring and cooling systems has been hampered by discoveries of hazardous radioactive water.

The risk to workers may be greater than previously thought because melted fuel in the No.1 building might be causing isolated, uncontrolled nuclear chain reactions, Mr Flory said at a media conference in Vienna.

Nuclear experts call these reactions localised criticality, which will increase radiation and hamper the ability to shut down the plant. Twenty-one workers have been killed by ”criticality accidents” in the past, the website of the Los Alamos National Laboratory in the US said.

Radioactive chlorine found last Friday in the unit 1 turbine building suggests chain reactions continued after the reactor shut down, Ferenc Dalnoki-Veress of the James Martin Centre for Nonproliferation Studies in California, wrote in a paper this week. Radioactive chlorine has a half-life of 37 minutes, the report said.

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