Assertion: natural uranium | /r/MadeOf | a mixture of various isotopes
Facets:
value: primarily
type: DEGREE
Source sentences:
text: Natural uranium consists of a mixture of various isotopes, primarily U-238 and a much smaller amount (about 0.72% by weight) of U-235. U-238 can only be fissioned by neutrons that are fairly energetic, about 1 MeV or above.