" from a distance of 50 miles, were brought down in 10 seconds by demolition explosives, and that was that. The fuel-reprocessing industry in the UK has reported only one criticality accident in which fissile material managed to come together accidentally in a supercritical configuration. Just about every other country that has tried to separate plutonium from uranium in spent reactor fuel has experienced at least one such excursion, and this was Britain’s. This incident at the Windscale Works on August 24, 1970, is described by the criticality review committee at "

― James Mahaffey , Atomic Accidents: A History of Nuclear Meltdowns and Disasters: From the Ozark Mountains to Fukushima