Chernobyl disaster substantial levels of caesium, which were believed to have been passed onto them during their consumption by wild boars, a significant number of which already contained radioactive particles above the allowed level. Like many other releases of radioactivity into the environment, the Chernobyl release was controlled by the physical and chemical properties of the radioactive elements in the core. Particularly dangerous are the highly radioactive fission products, those with high nuclear decay rates that accumulate in the food chain, such as some of the isotopes of iodine, caesium and strontium. Iodine-131 and caesium-137 are responsible for most of the radiation
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