The Chernobyl disaster was a nuclear reactor accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine (then part of the Soviet Union). It is considered to be the worst nuclear power plant disaster in history and the only level 7 event on the International Nuclear Event Scale. It resulted in a severe release of radioactivity following a massive power excursion that destroyed the reactor. Most deaths from the accident were caused by radiation poisoning.
On April 26, 1986 at 01:23 a.m. (UTC+3) reactor number four at the Chernobyl plant, near Pripyat in the Ukrainian Soviet Socialist Republic, exploded. Further explosions and the resulting fire sent a plume of highly radioactive fallout into the atmosphere and over an extensive geographical area. Four hundred times more fallout was released than had been by the atomic bombing of Hiroshima.
