A succession of generation after generation of acts of division (called fission) of certain heavy nuclei. The fission process releases about 200 MeV (3.2 × 10^-4 erg = 3.2 × 10^-11 joule) in the form of energetic particles including two or three neutrons. Some of the neutrons from one generation are captured by fissile species (²³³U, ²³⁵U, ²³⁹Pu) to cause the fissions of the next generations. The process is employed in nuclear reactors and nuclear explosive devices.