The Fukushima nuclear disaster released twice as much of a radioactive substance into the atmosphere as Japanese authorities estimated, reaching 40 percent of the total from Chernobyl, a preliminary report says.
The estimate of much higher levels of radioactive cesium-137 comes from a worldwide network of sensors. Study author Andreas Stohl of the Norwegian Institute for Air Research says the Japanese government estimate came only from data in Japan, and that would have missed emissions blown out to sea.
Last summer, the Japanese government estimated that the March 11 Fukushima accident released 15,000 terabecquerels of cesium. Terabecquerels are a radiation measurement. The new report from Stohl and co-authors estimates about 36,000 terabecquerels through April 20. That’s about 42 percent of the estimated release from Chernobyl, the report says.
The amount of radioactive cesium-137 that flowed into the Pacific after the start of Japan’s nuclear crisis was probably nearly 30 times the amount stated by Tokyo Electric Power Co. in May, according to a recent report by a French research institute.
The Institute for Radiological Protection and Nuclear Safety said the amount of the isotope that flowed into the ocean from the Fukushima Daiichi nuclear plant between March 21 and mid-July reached an estimated 27.1 quadrillion becquerels.
A quadrillion is equivalent to 1,000 trillion.
A trillion becquerels equals a terabecquerel. so the Cesium-137 release into the ocean as estimated would equal 27,100 terabecquerels.
But the institute warned that a significant degree of pollution would remain in waters off the coast of Fukushima Prefecture, northeast of Tokyo.