On 26 April 1986 the Number 4 reactor of the V.I. Lenin nuclear power station at Chernobyl (Ukraine) exploded.
The Soviet Union admitted the accident four days after it occurred as high radiation levels were detected in Scandinavia.
According to the brief Russian statement, the other three reactors in the plant had been shut down, and two people had been killed with nearby places evacuated.
Pictures taken by American satellites indicated that the top of the reactor was blown off in an explosion.
The reactor was on fire and the Russians asked for help in fighting it from Sweden and West Germany. Other offers of assistance, including one from the International Atomic Energy Agency, were refused.
Russian reactors did not have containment buildings, normal in the West, to prevent the release of radioactivity after an accident.