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Uranium-238 (238 U or U-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239.
Consequently, uranium-238 is fissionable but not fissile. [4] [5] An alternative definition defines fissile nuclides as those nuclides that can be made to undergo nuclear fission (i.e., are fissionable) and also produce neutrons from such fission that can sustain a nuclear chain reaction in the correct setting.
Natural uranium contains about 0.72% 235 U. Depleted uranium has lower mass fractions—up to three times less—of 235 U and 234 U than natural uranium. Since 238 U has a much longer half-life than the lighter isotopes, DU is about 40% less radioactive than natural uranium.
Uranium-238 is the most stable isotope of uranium, with a half-life of about 4.463 × 10 9 years, [7] roughly the age of the Earth. Uranium-238 is predominantly an alpha emitter, decaying to thorium-234. It ultimately decays through the uranium series, which has 18 members, into lead-206. [17]
Despite the U.S. women's water polo team's success — winning gold medals at the 2012, 2016 and 2020 Summer Olympics — the sport doesn't get the same support that soccer, basketball and ...
Maggie Steffens asked for more support for the U.S. women’s water polo team, and the captain received one particularly surprising response. From a clock-wearing rap icon.
HIGH SCHOOL BOYS WATER POLO. SOUTHERN SECTION PLAYOFFS. THURSDAY’S RESULTS. DIVISION 1. First Round . Westlake 13, Portola 12. El Segundo 17, La Habra 10. Yucaipa 12, Crean Lutheran 7. San Juan ...
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] U-233 is produced from thorium-232 by neutron capture. [19]