On 26th April 1986, a routine safety test went catastrophically wrong and triggered the worst nuclear accident of all time. The incident at the Chernobyl Nuclear Power Plant near Pripyat, Ukraine led to the release of 400 times more radiation than the atomic bomb dropped on Hiroshima during WW2.
Throughout Friday, 25th April 1986, Chernobyl's engineers lowered power at Reactor No. 4 in preparation for a safety test to be conducted later that evening. The test was supposed to check whether the reactor turbines could continue powering emergency water coolant pumps in the event of a power failure. Ironically, the safety test was anything but safe as human error and substandard reactor design led to a partial meltdown of the core. The experiment was poorly conceived and equally badly executed. Firstly, the less-experienced night shift crew carried out the safety test and later claimed they had not received full instructions from the day shift crew on how to properly conduct it. Secondly, the emergency core cooling system for Reactor 4 was disabled along with the emergency shutdown system. Finally, the reactor’s power level dropped to a dangerously unstable level at which point the engineers removed most of the control rods in violation of safety guidelines. Although power began to return, it was far from under control.
