How did the Chernobyl nuclear reactor disaster occurr?

Answer 1

The explanations of the Chernobyl disaster are, in a nutshell:

• The No.4 reactor operators were testing the emergency cooling system of the reactor, by doing this they took out all of the control rods to allow the reactor to get hot.
• A power surge occurred knocking out the power in the power plant and disabling the main water pumps and allowing the reactor to rise in temperature uncontrollably.
• Pressure was lost inside the reactor and the water started to boil increasing the reactors temperature.
• The fuel rods got very hot and expanded and cracked preventing the control rods being re-inserted back into the reactor.
• The graphite moderator caught fire increasing the reactors temperature even more.
• Reactor got to critical temperature and a meltdown occurred(when the nuclear core melts), molten uranium melted straight through the reactor floor until it reached cold water.
• This contact of hot uranium and cold water causes a high pressure steam burst(thermal explosion) which rushes up the reactor and blowing the roof off.
• Smoke from the graphite fire mixed in with the radioactive dust and was carried all over Europe.