Chernobyl

On April 26, 1986, an accident occurred at Unit 4 of the Chernobyl nuclear power plant. The accident destroyed the reactor, contaminated large areas surrounding the reactor, and led to an increase in radiation levels over practically the whole of the Northern Hemisphere. The site is near the present borders of Belarus, the Russian Federation, and Ukraine; at the time of the accident, the plant was in the Ukrainian Republic of the Union of Soviet Socialist Republics.

The Chernobyl power station consisted of four Soviet-designed light water-cooled graphite-moderated (in Russian the Reaktor Bolshoy Moshchnosti Kanalnyy, meaning “high-power channel-type reactor”) reactors of 950 MW each. These units used graphite to moderate the nuclear reaction and used water flowing through channels holding the fuel elements to cool it. ...