The Demon Core Claims Slotin: Nuclear Dangers Exposed

The plutonium sphere had already killed one physicist. On May 21, 1946, it claimed another. Louis Slotin stood in a Los Alamos laboratory, demonstrating a criticality experiment by lowering a beryllium hemisphere over a 6.2-kilogram plutonium core using nothing but a screwdriver to maintain the gap. His hand slipped, the hemisphere dropped, and the room filled with a blue flash of ionizing radiation. Nine months earlier, Harry Daghlian had received a fatal dose from the same core during a similar experiment. Scientists at Los Alamos had already nicknamed it the "demon core," and the hand-assembly technique Slotin was performing was known internally as "tickling the dragon's tail." Richard Feynman compared it to playing Russian roulette. Slotin instinctively flipped the beryllium hemisphere off the core, stopping the chain reaction within a second. That single second delivered roughly 1,000 rads to his body. He calmly told the seven other people in the room their positions relative to the core, information that would determine their medical treatment and their odds of survival. All seven lived. Slotin did not. Over the following nine days, Slotin's body deteriorated in a pattern that became a landmark case study in acute radiation syndrome. His hands blistered first, then internal organs began failing. He died on May 30, 1946, at age 35, fully conscious until near the end. The accident ended hand-assembly criticality experiments at Los Alamos permanently. The demon core was melted down and recycled into the nuclear stockpile. Slotin's death helped establish the remote-handling safety protocols that govern nuclear research to this day.