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Natural uranium is made weapons-grade through isotopic enrichment. Initially only about 0.7% of it is fissile U-235, with the rest being almost entirely uranium-238 (U-238). They are separated by their differing masses. Highly enriched uranium is considered weapons-grade when it has been enriched to about 90% U-235. [citation needed]
Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235 U) has been increased through the process of isotope separation.Naturally occurring uranium is composed of three major isotopes: uranium-238 (238 U with 99.2732–99.2752% natural abundance), uranium-235 (235 U, 0.7198–0.7210%), and uranium-234 (234 U, 0.0049–0.0059%).
The nominal spherical critical mass for an untampered 235 U nuclear weapon is 56 kilograms (123 lb), [6] which would form a sphere 17.32 centimetres (6.82 in) in diameter. The material must be 85% or more of 235 U and is known as weapons grade uranium, though for a crude and inefficient weapon 20% enrichment is sufficient (called weapon(s)-usable).
Iran is "dramatically" accelerating its enrichment of uranium to up to 60% purity, close to the roughly 90% level that is weapons grade, U.N. nuclear watchdog chief Rafael Grossi told Reuters on ...
North Korea has disclosed the first photos of a uranium enrichment site designed to produce weapons-grade fuel for its nuclear bombs. Here's what we know about its growing nuclear arsenal.
Uranium enriched up to 60% purity is just a short, technical step away from weapons-grade levels of 90%. Iran has further increased its stockpile of uranium enriched to near weapons-grade levels ...
Natural uranium (NU or U nat [1]) is uranium with the same isotopic ratio as found in nature. It contains 0.711% uranium-235 , 99.284% uranium-238 , and a trace of uranium-234 by weight (0.0055%). Approximately 2.2% of its radioactivity comes from uranium-235, 48.6% from uranium-238, and 49.2% from uranium-234.
Iran has begun enriching uranium close to weapons-grade levels, according to a report released by the United Nations nuclear watchdog Wednesday.