25-26 April 1986 Engineers on the night move at Chernobyl’s number four reactor began an investigation to see whether the cooling pump framework could in any case work using the power created from the reactor under low power should the partner control supply crash and burn.
At 11:00pm control poles, which deal with the splitting procedure in an atomic reactor by holding neutrons and directing the chain response, were brought down to decrease yield to around 20% of ordinary yield required for the test. Be that as it may, an excessive number of poles were brought down, and yield dropped too rapidly, bringing about a relatively entire shutdown. Security systems disabled Stressed by conceivable insecurity, engineers started to raise the poles to build yield. At 00:30am the decision was taken to proceed. By 01:00am power was still just at around 7%, so more poles were raised. The programmed shutdown framework was hindered to empower the reactor to continue working under low power conditions. The architects kept on raising bars. By 01:23am, control had achieved 12% and the test started.
Be that as it may, seconds after the fact, control levels suddenly raced to hazardous levels. Overheating The reactor started to overheat, and its water coolant began to swing to steam. Now it is trusted that everything except six control bars had been segregated from the reactor centre. The crisis shutdown catch was squeezed.
Control bars began to enter the centre, yet their reinsertion from the best uprooted coolant and centred reactivity in the lower centre. Blasts With control at around 100 times ordinary, fuel pellets in the centre started to detonate, breaking the fuel channels. At around 01:24am, two blasts happened.
As air was sucked in to the smashed reactor, it lighted combustible carbon monoxide gas causing a reactor fire which burned for nine days. The building managed extreme harm and bountiful measures of radioactive flotsam and jetsam got away into the climate.