Natural uranium can be used to fuel both low- and high-power nuclear reactors.
However, experimental fuelings with uranium trioxide (UO3) and triuranium octaoxide (U3O8) have shown promise.
[2] The 0.72% uranium-235 is not sufficient to produce a self-sustaining critical chain reaction in light water reactors or nuclear weapons; these applications must use enriched uranium.
On rare occasions, earlier in geologic history when uranium-235 was more abundant, uranium ore was found to have naturally engaged in fission, forming natural nuclear fission reactors.
During the Manhattan Project, the name Tuballoy was used to refer to natural uranium in the refined condition; this term is still in occasional use.