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
Radiation effects from the Fukushima Daiichi nuclear disaster put out a total of 85 PBq of caesium-137. However, later reporting on 12 April estimated total caesium releases at 6.1 PBq to 12 PBq, respectively by NISA and NSC – about 2–4 kg. On 23 April, NSC updated this number to 0.14 TBq per hour of caesium-137 on 5 April, but did not recalculate the entire release estimate. On 12 October 2011 a concentration of 195 becquerels/kilogram of Strontium-90 was found in the sediment on the roof of an apartment building in the city of Yokohama, south of Tokyo, some 250 km from the plant in Fukushima. This first