The nuclear fuel is the material used for the generation of nuclear energy. It is a material that can be fissionable or fused according to whether their use is nuclear fission or nuclear fusion.
We refer to both nuclear fuel material (uranium, plutonium ...) as the set made with such nuclear material (fuel rods, nuclear material compositions and the moderator or any other combination.
The best known nuclear fuel is uranium because it is the most used in nuclear fission reactors. All nuclear reactors currently in production for the generation of electrical energy are fission. At another level, plutonium is also used as nuclear fuel.
Tritium and deuterium light isotopes are used in the process of nuclear fusion. Nuclear fusion, for the moment, is not sufficiently developed so that it can be applied in nuclear power plants although in France is building a nuclear fusion reactor (ITER) for study.