highly enriched uranium

== English == === Noun === highly enriched uranium (uncountable) (nuclear physics, military) Enriched uranium containing at least 20% uranium-235 (some applications, such as fission weapons and naval reactors, use uranium enriched to as high as 80-95% uranium-235), and therefore capable of sustaining a nuclear fission chain reaction without needing a moderator; used in nuclear weapons and in a few types of nuclear reactors requiring very high power density or high neutron flux. Alternative forms: HEU (initialism), highly-enriched uranium Synonym: weapons-grade uranium Hypernyms: enriched uranium < U, uranium Coordinate terms: SEU, slightly enriched uranium; LEU, low-enriched uranium; NU, natural uranium; DU, depleted uranium