The Demon Core: Plutonium Sphere That Killed Two Scientists

Added: 2026-06-02

[00:00:00]Did you know a single sphere of plutonium killed two brilliant scientists and nearly caused a nuclear disaster? They called it the demon core.

[00:00:08]In 1945, Los Alamos scientist Harry Daghlian was working alone late at night. He was stacking tungsten bricks around the plutonium sphere when one brick slipped from his hand. It fell onto the core. Instantly, the room filled with blue light. The core had gone critical. Daghlian knocked the brick away with his bare hand, but it was too late. He died 25 days later, his body slowly destroyed by radiation.

[00:00:30]9 months later, physicist Louis Slotin was demonstrating the same core to colleagues. He was holding two half spheres apart with just a screwdriver.

[00:00:38]The screwdriver slipped. The spheres closed. Another blue flash filled the room. Slotin quickly separated them, saving everyone else, but he had absorbed a lethal dose. He died 9 days later in agony. The same 6 kg sphere.

[00:00:51]Two dead scientists, and it almost became the third atomic bomb dropped in anger. The demon core lived up to its name.