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How does an uncontrolled nuclear fission chain reaction produce an atomic explosion?
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actinoid element
Modern version of the periodic table of the elements (printable).
An atomic explosion is the result of an uncontrolled, rapidly multiplying nuclear fission chain reaction involving fissile material, such as uranium-235 or plutonium-239.123
The process occurs as follows:
- Fission Initiation: When a neutron strikes a heavy, unstable nucleus, the nucleus splits into two lighter fragments, releasing a significant amount of energy, gamma rays, and two or more additional neutrons.43
- Chain Reaction: These newly released neutrons strike nearby nuclei, inducing further fissions. If the system is supercritical—meaning more than one neutron from each fission event successfully triggers another—the number of fissions grows exponentially.123
- Explosive Release: In an atomic bomb, this process is designed to occur as rapidly as possible. By bringing subcritical masses together or compressing material via implosion, the material reaches a supercritical state. The resulting near-instantaneous release of energy creates a devastating explosion characterized by intense heat, a powerful shock wave, and radioactive fallout.13
Unlike a nuclear reactor, which uses control rods to maintain a steady, critical state, an atomic weapon seeks to maximize the multiplication factor to ensure the maximum amount of material fissions in a fraction of a second.125