Nuclear reactor disaster - The worst nuclear reactor disaster was that at Chernobyl, USSR in April 1986. At the time reports quoted a figure of 31 dead, although estimates for the eventual death toll vary between 200 and 600 (a 1987 Soviet estimate) and 75,000 (an American estimate), and Moscow News reported on 8 Nov 1989 that at least 250 people working at Chernobyl or involved in the rescue operation had died in the 3 1/2 years since April 1986. One of the major tasks following the accident was the decontamination of buildings (Photo: Gamma/Novosti)