Chain Reaction
In nuclear fission, a self-sustaining series of reactions where neutrons released by splitting one atom cause additional atoms to split, releasing more neutrons and energy. Reactors control this process; bombs let it run away.
Why It Matters
Understanding that reactors maintain a controlled chain reaction (not an explosion) is fundamental to understanding nuclear safety. The reactor operates at "criticality" — each fission event triggers exactly one more.
Related Topics
Related Terms
Nuclear Fission
The process of splitting a heavy atomic nucleus (such as uranium-235 or plutonium-239) into two lighter nuclei, releasing a large amount of energy. This is the reaction that powers all current nuclear power plants.
Uranium
A naturally occurring radioactive element used as fuel in nuclear reactors. Natural uranium is 99.3% U-238 and 0.7% U-235. Most reactors require enrichment to 3-5% U-235.