Fissile Material [Energy] Law and Legal Definition

According to 10 CFR 71.4 [Title 10 – Energy; Chapter I -- Nuclear Regulatory Commission; Part 71 -- Packaging and Transportation of Radioactive Material; Subpart A -- General Provisions], the term Fissile material means the radionuclides uranium-233, uranium-235, plutonium-239, and plutonium-241, or any combination of these radionuclides. Fissile material means the fissile nuclides themselves, not material containing fissile nuclides. Unirradiated natural uranium and depleted uranium and natural uranium or depleted uranium that has been irradiated in thermal reactors only, are not included in this definition. Certain exclusions from fissile material controls are provided in § 71.15.