Critical Mass

Critical mass is the minimum amount of fissile material, such as uranium-235 or plutonium-239, needed to sustain a nuclear chain reaction. When sufficient atoms of the material are present, each fission event releases neutrons that can trigger further fission in nearby atoms. If there’s too little material, neutrons escape without causing more reactions, and the chain reaction stops. At critical mass, the reaction becomes self-sustaining, leading to the release of a significant amount of energy. This concept is crucial for the design of nuclear reactors and atomic bombs, where controlling the chain reaction is essential for safety and functionality.