Detection of radiation 650km from the Japanese coast

Radioactivity from the nuclear disaster at the Fukushima plant was discovered about 650 km away from the Japanese coast, in the Pacific Ocean, with a radiation index 1,000 times higher than the previous one.

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However, radioactive cesium-137 concentrations are below the danger for animals and seafood eaters, said Ken Buesseler, of Woods Hole, Massachusetts Institute of Oceanography.

The information was published yesterday in Salt Lake City, during the annual Ocean Science conference, attended by more than 4,000 researchers.

The results came from water samples in June, three months after the Fukushima nuclear power plant disaster. In addition to thousands of water samples, the researchers also took samples of fish and plankton, but found that cesium-137 was much lower than the health limit.

Fukushima Power Plant

According to Buesseler, water samples were taken from a range of about 30 to 650 km from the east coast of the Fukushima plant. The concentration of radioactive cesium-137, likely to cause cancer, is 10 - 1,000 times higher than normal. However, this level is still only about 1/10 of the level considered harmful.

Cesium-137 is not the only radioactive substance released from the Fukushima plant, but is of particular interest because it exists long in the environment. Its life cycle or decay period is up to 30 years.

Buesseler said the highest radioactivity index last June was not always close to the Fukushima plant. Because swirling currents have created the accumulation of radioactivity.

In addition, most of the radioactive cesium-137 has probably been absorbed into the ocean through waste water, not in air dust.

Hartmut Nies, of the International Atomic Energy Agency, said Buesseler's discovery is not surprising, due to its vast ocean and its ability to absorb and dilute substances.'This is what we had anticipated,' Mr. Nies said after Mr. Buesseler presented his research.

Mr. Nies also said that the concentration of cesium-137 in the country was greatly diluted when it was only 30km from the coast.'If it is not sea water, you can drink water without any problems'.