Chernobyl event

An accident at the Chernobyl nuclear power plant (Ukraine) on April 26th, 1986 to be assigned a index 7 on the International Nuclear Event Scale (INES). The explosion exposed the reactor core and released radioactive fission and neutron activation products, including transuranics from the reactore to the atmosphere. More than 140 000 km2 of the territory of Ukraine, Belarus and the Russian Federation, and more than 45 000 km2 of other European countries were contaminated with 137Cs over 40 kBq/m2.