Fukushima Daiichi nuclear disaster for caesium-137, which is about 11% of Chernobyl emissions. Earlier estimations were 150 PBq and 12 PBq. In 2011, scientists working for the Japan Atomic Energy Agency, Kyoto University and other institutes, recalculated the amount of radioactive material released into the ocean: between late March through April they found a total of 15 PBq for the combined amount of iodine-131 and caesium-137, more than triple the 4.72 PBq estimated by TEPCO. The company had calculated only the direct releases into the sea. The new calculations incorporated the portion of airborne radioactive substances that entered the ocean as rain. In the
Timeline of the Fukushima Daiichi nuclear disaster Economist reports that high levels of radioactive particles, including plutonium have been found in an extended irregular zone that extends well outside the 30 km evacuation radius around the Fukushima Dai-ichi nuclear power plant. A French study by the Institute for Radiological Protection and Nuclear Safety revealed that the Fukushima nuclear disaster caused the biggest discharge of radioactive material into the ocean in history. The radioactive caesium that flowed into the sea from the Fukushima Dai-Ichi nuclear plant was 20 times the amount estimated by its owner, Tokyo Electric Power Co. Atmospheric releases were cited as amounting to 35,800 terabecquerels