Fissile material
material capable of sustaining a nuclear fission chain reaction
In nuclear engineering, fissile material is material that can undergo nuclear fission when struck by a neutron of low energy. A self-sustaining thermal chain reaction can only be achieved with fissile material. The predominant neutron energy in a system may be typified by either slow neutrons (i.e., a thermal system) or fast neutrons. Fissile material can be used to fuel thermal-neutron reactors, fast-neutron reactors and nuclear explosives.
Fissile vs fissionable
The term fissile is distinct from fissionable. A nuclide that can undergo nuclear fission (even with a low probability) after capturing a neutron of high or low energy is referred to as fissionable. A fissionable nuclide that can undergo fission with a high probability after capturing a low-energy thermal neutron is referred to as fissile. Fissionable materials include those (such as uranium-238) for which fission can be induced only by high-energy neutrons. As a result, fissile materials (such as uranium-235) are a subset of fissionable materials.
Uranium-235 fissions with low-energy thermal neutrons because the binding energy resulting from the absorption of a neutron is greater than the threshold required for fission; therefore uranium-235 is fissile.
This brief starts where responsible research should: with the source description of “Fissile material” as material capable of sustaining a nuclear fission chain reaction. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the general reference register because the source frames it as material capable of sustaining a nuclear fission chain reaction. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Feb 13, 2026. The linked authority identifier is Q483674. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Fissile material” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.