In naitur, uranium is foond as uranium-238 (99.2739–99.2752%), uranium-235 (0.7198–0.7202%), an a verra smaw amoont o uranium-234 (0.0050–0.0059%). Uranium decays slawly bi emittin an alpha pairticle. The hauf-life o uranium-238 is aboot 4.47 billion years an that o uranium-235 is 704 million years, makkin them uisefu in datin the age o the Yird.
Mony contemporary uises o uranium exploit its unique nuclear properties. Uranium-235 is the anly naiturally occurrin fissileisotope, that maks it widely uised in nuclear pouer plants an nuclear wappens. Houiver, acause o the teenie amoonts foond in naitur, uranium needs tae unnergae enrichment sae that eneuch uranium-235 is present. Uranium-238 is fissionable bi fest neutrons, an is fertile, meanin it can be transmutit tae fissile plutonium-239 in a nuclear reactor. Anither fissile isotope, uranium-233, can be produced frae naitural thorium an is an aa important in nuclear technology. Uranium-238 haes a smaw probability for spontaneous fission or even induced fission wi fest neutrons; uranium-235 an tae a lesser degree uranium-233 hae a muckle heicher fission cross-section for slaw neutrons. In sufficient concentration, thir isotopes mainteen a susteened nuclear cheen reaction. This generates the heat in nuclear pouer reactors, an produces the fissile material for nuclear wappens. Depletit uranium (238U) is uised in kinetic energy penetrators an airmour platin. Uranium is uised as a colourant in uranium gless, producin leemon yellae tae green colors. Uranium gless fluoresces green in ultraviolet licht. It wis an aa uised for tintin an shadin in early photografie.