At 1:24 AM local time, 40-60 seconds after commencing the experiment, two large explosions at Chernobyl nuclear power plant took place. According to some accident investigators, taking off all the absorbing sticks from the active zone of the reactor, together with the reactor’s growing power capacity, the crash was unavoidable.
It was recorded that safety systems were shut off or even out of service at the time of the initial explosion and the explosion of steam and hydrogen blew the 1200 ton cover of the reactor and destroyed the roof. After a few seconds there came the second explosion.
According to several independent studies, while the first explosion was normal – chemical, the second explosion with the burning of the prompt neutrons, it had characteristics of a nuclear explosion with a yield of 0.3 kilotons (equal to around 300 tons of TNT). According to witnesses the first explosion was followed by a red blaze and the second explosion had a light-blue blaze, after which a mushroom cloud rose above the reactor.