Setagaya Radiation likely came from radium in bottles beneath floor of empty house

Setagaya Ward officials said Thursday night that an extremely high level of radiation has been detected in bottles kept in a box beneath the floorboards of an unoccupied house in Setagaya, and that this is most likely the source of radiation detected on a nearby street on Wednesday.Researchers found radiation levels of 3.35 microsieverts per hour in tree leaves at a height of one meter by the fence of the unoccupied house along the street in Tsurumaki — much higher than previously reported levels. Initially, officials thought that the radiation may have come from the crippled Fukushima Daiichi nuclear power plant which is 220 kilometers away.

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Robots to gauge radiation at Japan’s Nuclear Plant

The operator of Japan’s stricken nuclear plant said Sunday it will send two remote-controlled robots into a reactor building damaged by a hydrogen explosion to gauge radiation and temperature levels.

Emergency workers battling to stabilise the plant after a massive earthquake and tsunami knocked out cooling systems on March 11 have not been able to enter any of the reactor buildings since the disaster.

The explosion — one of several caused when a build-up of hydrogen reacted with oxygen in the atmosphere in the days immediately after the quake — blew the roof off the outer structure housing reactor three.

A spokesman for the Tokyo Electric Power Co. (TEPCO) said the two American-made robots would enter the reactor three building on Sunday to check radiation, temperature, humidity and oxygen levels.

Radiation from the overheating reactors has made its way into the air, land and sea, leading the government to impose exclusion zones around the plant in Fukushima prefecture and damaging local fishing and farming industries.

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Japan Cites Possibility of Breach in Reactor Vessel of the No. 3 Unit

Japan’s effort to contain the crisis at the Fukushima Daiichi nuclear plant suffered a setback, an official said on Friday,  citing evidence that the reactor vessel of the No. 3 unit may have been damaged.

The development, described at a news conference by Hidehiko Nishiyama, deputy director-general of the Japan Nuclear and Industrial Safety Agency, raises the possibility that radiation from the mox fuel in the reactor — a combination of uranium and plutonium — could be released.

One sign that a breach may have occurred in the reactor vessel, Mr. Nishiyama said, took place on Thursday when three workers who were trying to connect an electrical cable to a pump in a turbine building next to the reactor were injured when they stepped into water that was found to be significantly more radioactive than normal in a reactor. The No. 3 unit, the only one of the six reactors at the site that uses the mox fuel, was damaged by a hydrogen explosion on March 14. Workers have been seeking to keep it cool by spraying it with seawater along with a more recent effort to restart the reactor’s cooling system.

In another development on Friday, the Japanese government said it would help people who wish to leave the area around the crippled plant, a sign that efforts to reassure frightened residents have failed to persuade people to stay.

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TEPCO hikes radiation limits as workers’ exposure rises

Tokyo Electric Power Company said some workers at the Fukushima Daiichi plant have already been exposed to more than 100 millisieverts and that the company, citing the unprecedented nature of the crisis, has raised the limit to 150 millisieverts for some outdoor workers.

After a single acute exposure of 1,000 millisieverts, people tend to start feeling nauseated and vomiting, Frey said. At 5,000 millisieverts over the course of a few hours, “people start dying.”
After exposure to 150 millisieverts per day, “you’re definitely in the range where you have significantly increased risk of radiation-induced cancers.”

For work involving recovery and restoration in an emergency operation, the International Commission on Radiological Protection recommends no more than 50 millisieverts in any given year. But in cases where the lives of a great number of people may be at stake, the ICRP says it recommends no restriction on dose as long as “the benefit to others clearly outweighs the rescuer’s risk.”

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