Nuclear accidents - Chernobyl (USSR)

At the time of the accident on April 26, 1986, Reactor No. 4 at the Chernobyl nuclear power plant was not in normal operation: it was undergoing a safety-related electrical test prior to a maintenance shutdown. After a few details on the design of RBMK reactors, this article describes how this test was carried out under conditions different from those initially planned, by transgressing various rules for this type of reactor with low-power instability ranges, which led to the reactor's explosion. The article then presents some of the effects of the accident on the environment and the population. Finally, it describes the lessons learned from this disaster by the former USSR and the Western world.