Nuclear Fission
A nuclear reaction in which a heavy nucleus splits into two or more smaller daughter nuclei accompanied by the release of neutrons and substantial energy.
Governing formula
¹₀n + ²³⁵₉₂U → ²³⁶₉₂U* → ¹⁴¹₅₆Ba + ⁹²₃₆Kr + 3 ¹₀n + Q (~200 MeV)
SI unit
MeV (Mega-electronvolts)
In depth
Fission occurs when absorbing a thermal neutron causes a heavy fissile nucleus (like Uranium-235 or Plutonium-239) to distort beyond its stability threshold. The combined mass of fission fragments is less than the original mass, converting the mass defect into ~200 MeV of kinetic and gamma energy per reaction according to E = Δm c².
Examples in the real world
Uranium-235 fuel fission sustaining thermal energy output in commercial nuclear power plants.