Enriched uranium

Enriched uranium is uranium that has been processed to increase the concentration of the isotope uranium-235, which is necessary for nuclear reactors and weapons. Natural uranium contains about 0.7% uranium-235, but enrichment raises this level to around 3-5% for reactor fuel or much higher for weapons. The process removes most of the uranium-238 isotope, making the remaining uranium more suitable for sustained nuclear fission reactions. Enriched uranium is carefully controlled because of its potential for energy production and, in higher grades, for weaponization.