uranium

ura*ni*um

noun

{bc}a silvery heavy radioactive polyvalent metallic element that is found especially in {a_link|uraninite} and exists naturally as a mixture of mostly nonfissionable isotopes {dx}see {dxt|Chemical Elements Table|element|table}{/dx}

uranium hexa*flu*o*ride

noun

{bc}a volatile compound UF{inf}6{/inf} of uranium and fluorine that is used in one major process of enriching uranium in uranium 235

uranium 238

noun

{bc}an isotope of uranium of mass number 238 that is the most stable uranium isotope, that constitutes over 99 percent of natural uranium, that is not fissile but can be used to produce a fissile isotope of plutonium, and that has a half-life of 4.5 billion years

uranium 235

noun

{bc}a light isotope of uranium of mass number 235 that constitutes less than one percent of natural uranium, that when bombarded with slow neutrons undergoes rapid fission into smaller atoms with the release of neutrons and energy, and that is used in nuclear reactors and atomic bombs