Environmental radioactivity part of the Chernobyl release was the caesium-137, this isotope is responsible for much of the long term (at least one year after the fire) external exposure which has occurred at the site. The caesium isotopes in the fallout have had an effect on farming. A large amount of caesium was released during the Goiânia accident where a radioactive source (made for medical use) was stolen and then smashed open during an attempt to convert it into scrap metal. The accident could have been stopped at several stages; first, the last legal owners of the source failed to make arrangements
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