radioactive matter
any matter exposing noticable radioactivity
nuclear material
any isotope or form of one of the metals uranium, plutonium, and according to some definitions thorium; material crucial for nuclear power and nuclear weapons
depleted uranium
uranium with a lower content of the fissile isotope U-235 than natural uranium
enriched uranium
uranium in which the proportion of uranium-235 has been increased through the process of isotope separation
radioactive waste
waste containing radioactive material and emitting ionizing radiation