On this day in 1946, Louis Slotin accidentally triggered a supercritical nuclear chain reaction, which released a burst of hard radiation. He was rushed to the hospital and died nine days later on 30 May. Slotin had become the second fatal victim of a criticality accident in history, following Harry Daghlian, who had died of a related accident with the same plutonium “demon core” the previous year.
The demon core was a sphere of plutonium–gallium alloy. It was a subcritical mass that weighed 6.2 kilograms (14 lb) and was 89 millimeters (3.5 in) in diameter; the core was prepared for shipment to the Pacific Theater as part of the third nuclear weapon to be dropped on Japan, but when Japan surrendered, the core was retained for testing and potential later use in the case of another conflict.
The core, once assembled, was designed to have only a small safety margin against extraneous factors that might increase reactivity, causing the core to become supercritical, and then prompt critical, a brief state of rapid energy increase. the addition of more nuclear material, or provision of an external reflector which would reflect outbound neutrons back into the core would lead to supercriticality.
he experiments conducted at Los Alamos leading to the two fatal accidents were designed to guarantee that the core was indeed close to the critical point by arranging such reflectors and seeing how much neutron reflection was required to approach supercriticality.
On May 21, 1946, physicist Louis Slotin and seven other personnel were in a Los Alamos laboratory conducting another experiment to verify the closeness of the core to criticality by the positioning of neutron reflectors. It required the operator to place two half-spherical shells of beryllium (a neutron reflector) around the core to be tested and manually lower the top reflector over the core using a thumb hole at the polar point. As the reflectors were manually moved closer and farther away from each other, neutron detectors indicated the core’s neutron multiplication rate. The experimenter needed to maintain a slight separation between the reflector halves to allow enough neutrons to escape from the core in order to stay below criticality.
On the day of the test, Slotin used a screwdriver to keep the two halves of the reflector slightly apart. Slotin’s screwdriver slipped outward a fraction of an inch while he was lowering the top reflector, allowing the reflector to fall into place around the core. Instantly, there was a flash of blue light; the core had become supercritical, releasing an intense burst of neutron radiation. Slotin quickly twisted his wrist, flipping the top shell to the floor. There was an estimated half-second between when the sphere closed to when Slotin removed the top reflector. The reaction in the room was one of immediate, somber realization. Slotin received a lethal dose in less than a second. While the position of his body over the apparatus shielded the others from much of the neutron radiation, his own exposure was irreversible. Slotin reportedly turned to his colleagues in the hushed room and famously uttered the remark, “Well, that does it.” He died nine days later from acute radiation poisoning.
Louis Slotin’s Los Alamos badge mugshot
When you want to rough it by going camping…
Today is the birthday, in 1955, of Stan Lynch, American musician, songwriter and record producer who was the original drummer for Tom Petty & The Heartbreakers, (1977 single ‘American Girl’, 1989 UK No.28 single ‘I Won’t Back Down’, 1991 UK No.3 album ‘Into The Great Wide Open’). He partnered with longtime friend Don Henley to help put together Eagles’ reunion album Hell Freezes Over and as a producer and writer, Lynch has worked with a diverse array of acts, such as The Band, Eagles, Don Henley, Jackopierce, Joe 90, Scotty Moore, The Fabulous Thunderbirds, The Jeff Healey Band, Tim McGraw and Ringo Starr. https://www.youtube.com/watch?v=nvlTJrNJ5lA
