Civil Nuclear Fission

The use of nuclear fission to generate power. The atom that undergoes fission is the naturally unstable and fissile isotope uranium U235, which is present in small quantities in natural uranium. The natural fission reaction — splitting of the nucleus into two smaller nuclei — is accelerated in the reactor using a nuclear fuel enriched with U235. This reaction releases heat, radiation and neutrons that in turn cause nearby atoms to split, in what is known as a chain reaction. The intense heat released is used to generate power.