This list comprises radioisotopes that are fissionable by neutrons of low kinetic energy. A simple way of distinguishing a 'fissile' nuclide from a 'fissionable' nuclide is that a fissile nuclide (such as uranium-233 or plutonium-239), when bombarded with neutrons, can be used to start off a nuclear chain reaction, producing a nuclear explosion. Most fissionable nuclides (such as uranium-238) fission at much higher energies than fissile materials.
Only isotopes with long enough half-lives to be used in a nuclear weapon or in a thermal reactor are listed.