1976 - near Greifswald, East Germany - at the Libmin nuclear power plant; the radioactive core almost melted down. There had been a fire, safety systems failed.
1979 - Three Mile Island, near Harrisburg, Pa., USA - a reactor lost its coolant, causing overheating and partial meltdown of an uranium core. The worst accident in American history. Some radioactive gases and water were released.
1986 - Chernobyl, near Kiev, Ukraine, Soviet Union - a graphite core of one of four reactors caught fire and exploded. Radioactive material spread far, to other parts of the Soviet Union, Scandinavia, eastern Europe, and eventually western Europe. Although authorities claimed 31 dead, nobody is really sure what the true figure was. The worst nuclear accident on earth.