the 'demon core incident' is another name for the second failed demonstration of a plutonium core made as part of the manhattan project during world war ii. the plutonium core, on may 21st 1946, accidentally had its neutron reflector dropped upon it. the person who was demonstrating it, louis slotin, was only using a screwdriver to hold the neutron reflector above the plutonium core in a subcritical position. the screwdriver fell out of place, causing the beryllium shell to fall onto the plutonium mass, causing it to go supercritical. the reaction of it killed everyone present in the demonstration in less than a month.
