On January 3, 1961, a three-man night crew -- CE1 Richard Legg and Army specialists John Byrnes and Richard McKinley -- had to restart the reactor after it had been shut down two weeks prior for the holidays. This task involved raising the central rod only four inches. For some reason, Byrnes lifted the rod 26 inches, and that's all it took to send the reactor supercritical. Its fuel melted and explosively vaporized, launching the reactor nine feet into the air and spreading radioactive debris all over the room.
This chain reaction took four seconds and killed Byrnes and Legg immediately. Emergency personnel rescued a heavily irradiated McKinley from the reactor room, but he passed away from his injuries while en route to a medical facility. In order to prevent him from contaminating anyone, the ambulance containing his body -- which was wrapped in lead blankets -- was dumped in the middle of the desert until it could be dealt with properly.
While McKinley and Byrnes were accounted for, no one could locate Legg. After they returned to the site for a brief search, his body was found pinned to the ceiling by a large plug that entered through his groin and out through his shoulder. It took six days to recover him, via a careful operation that involved guys with long poles knocking him off the ceiling onto a stretcher below, like the world's most horrifying carnival game.
Investigators were never able to figure out why Byrnes lifted the control rod so damn high. The best guess anyone can come up with is that the rod got stuck in its channel, and Byrnes, eager to get the job done, set about wrenching it free ... only for the rod to come loose and suddenly fly up. So let this be a cautionary tale about the value of elbow grease.