From NHK: "A group of Japanese researchers say that a total of 15,000 terabecquerels of radioactive substances is estimated to have been released from the crippled Fukushima Daiichi nuclear power plant into the sea. Researchers at the Japan Atomic Energy Agency, Kyoto University and other institutes made the calculation of radioactivity released from late March through April. The combined amount of iodine-131 and cesium-137 is more than triple the figure of 4,720 terabecquerels earlier estimated by Tokyo Electric Power Company, the plant operator. The utility only calculated the radioactivity from substances released from the plant into the sea in April and May. The researchers say the estimated amount of radioactivity includes a large amount that was first released into the air but entered the sea after coming down in the rain. They say they need to determine the total amount of radioactivity released from the crippled Fukushima Daiichi plant in order to accurately assess the impact of the disaster on the sea."