One of the most catastrophic man-made disasters happened in April 1986, both in terms of cost and casualties, when an explosion at the Chernobyl nuclear power plant in the USSR occurred during a late-night safety test. The test’s objective was the simulation of the station blackout power-failure. Therefore, both emergency safety and power-regulating systems were intentionally turned off. A combination of many errors led to an uncontrolled reaction conditions. Water flashed into steam generating a destructive explosion. The heat was so intense that it melted firefighters’ boots. The fire was finally contained on 4 May 1986.
Article : https://bigreflect.com/chernobyl-distaster-the-unforgettable-nuclear-catastrophe-that-took-place-in-1986/