| Abstract from DBPedia | Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (238U with 99.2739–99.2752% natural abundance), uranium-235 (235U, 0.7198–0.7202%), and uranium-234 (234U, 0.0050–0.0059%). 235U is the only nuclide existing in nature (in any appreciable amount) that is fissile with thermal neutrons. Enriched uranium is a critical component for both civil nuclear power generation and military nuclear weapons. The International Atomic Energy Agency attempts to monitor and control enriched uranium supplies and processes in its efforts to ensure nuclear power generation safety and curb nuclear weapons proliferation. There are about 2,000 tonnes of highly enriched uranium in the world, produced mostly for nuclear power, nuclear weapons, naval propulsion, and smaller quantities for research reactors. The 238U remaining after enrichment is known as depleted uranium (DU), and is considerably less radioactive than even natural uranium, though still very dense. Depleted uranium is used as a radiation shielding material and for armor-penetrating weapons.濃縮ウラン（のうしゅくウラン）は、ウラン濃縮により、ウラン235の濃度を天然ウランよりも高めたものである。天然ウランには、非核分裂性のウラン238に対して、核分裂性のウラン235が約0.7%の割合で含まれている。濃縮ウランはこの割合を人工的に高めたもので、濃縮後のウラン235の割合を濃縮度という。濃縮度が20%以下のものを低濃縮ウラン、20%を超えるものを高濃縮ウランという。なお、ウラン235の濃度が天然ウランを下回るものは劣化ウラン（減損ウラン）という。 (Source: http://dbpedia.org/resource/Enriched_uranium) |
