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Radiation levels soar at Japan nuclear plant

27 marca, 2011

Very high levels of radiation detected in water leaking from a reactor at a nuclear plant in Japan dealt a new setback Sunday to efforts to bring the stricken facility under control.

The operator of the Fukushima Daiichi plant said it had detected radiation levels 10 million times higher than usual in leaked water at reactor two, as white steam continued to rise from the tsunami-battered facility.

The radiation level was 1,000 millisieverts per hour, making it too dangerous to remain at the reactor turbine building and forcing the evacuation of workers there, plant operator Tokyo Electric Power said.

"It is an extremely high figure," nuclear safety agency spokesman Hidehiko Nishiyama said of the latest reading. "There is a high possibility that (the water) came from the reactor."

A single dose of 1,000 millisieverts can cause temporary radiation sickness, including nausea and vomiting. An exposure of 100 millisieverts per year is considered the lowest level at which an increase in cancer risk is evident.

Amid concerns that fuel rod vessels or their valves and pipes are leaking, chief government spokesman Yukio Edano admitted progress at the site was slow.

"We\'d like to be able to give a clear outline as to when this will be resolved," Edano told public broadcaster NHK on Sunday.

"But I can\'t be any more optimistic than what the reality of it is."

There was also a warning from the head of the world\'s atomic watchdog agency that Japan\'s nuclear emergency could go on for weeks, if not months, given the enormous damage to the plant, The New York Times reported.

Japanese authorities were still unsure about whether the reactor cores and spent fuel were covered with the water needed to cool them, Yukiya Amano, director general of the International Atomic Energy Agency, told the newspaper.

Urgent efforts to pump away pools of highly radioactive water near the reactors began Sunday, after several workers suffered radiation burns while installing cables as part of work to restore critical reactor cooling systems.

The incident has heaped yet more pressure on under-fire TEPCO after the workers, aged in their 20s and 30s, were exposed to highly radioactive water while wearing inadequate safety gear.

Edano pledged more effort would be made to improve the reporting of developments at the plant amid growing public unease over a flow of seemingly erratic and opaque information.

"We will have more detailed monitoring in high-risk areas and increase the capability of making forecasts so as not to be late in tackling this problem," he said.

Slow progress at the Fukushima site has added to the gloom hanging over the country since a 9.0-magnitude quake struck on March 11, sending a huge tsunami crashing into the northeast coast in Japan\'s worst post-war disaster.

The wave easily overwhelmed the world\'s biggest sea defences and erased entire towns.

The confirmed death toll stood at 10,489 Sunday, with 16,621 missing and 2,777 injured, the National Police Agency said.

The tsunami knocked out cooling systems for the six reactors at the Fukushima plant, leading to suspected partial meltdowns in three of them. Hydrogen explosions and fires have also ripped through the facility.

A worst-case scenario feared at the number-three reactor is that the fuel inside the reactor core -- a volatile uranium-plutonium mix -- has already started to burn its way through its steel pressure vessel.

Fire engines have hosed huge amounts of seawater onto the plant in a bid to keep the fuel rods inside reactor cores and pools from being exposed to the air, and prevent a full meltdown.

Several hundred metres offshore in the Pacific Ocean, levels of radioactive iodine some 1,850 times the legal limit were reported on Sunday, up from 1,250 times on Saturday, TEPCO said.

Japan\'s nuclear safety agency has ruled out an immediate threat to marine life and seafood safety, saying the radiation would be quickly dispersed by tides, amid some signs of gradual progress at the site.

The nuclear safety agency on Sunday said workers planned to start using electric pumps instead of firetrucks for cooling operations at reactor number one.

High-voltage electric cables have been reconnected to the reactors and power has been partially restored to enable lighting in some reactor control rooms.

Worried about the salt buildup in the crippled plant, engineers have started pumping fresh water into some of the reactors. The US military has supported the effort by sending two full water barges from a naval base near Tokyo.

Radioactive vapour from the plant has contaminated farm produce and dairy products in the region, leading to shipment halts in Japan as well as the United States, European Union, China and a host of other nations.

Singapore extended a ban on food imports from Japan on Saturday, suspending imports of all fruit and vegetables from the whole Kanto region, a large area including greater Tokyo.

Higher than normal radiation was last week detected in tap water in and around Tokyo, some 250 kilometres (155 miles) from the plant, leading authorities at one stage to warn against using it for baby milk formula.

Japan has encouraged those living up to 10 kilometres beyond the plant\'s 20 kilometre exclusion zone to leave. The 30 kilometre zone is below the 80 kilometres advised by the United States.