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Uranium-235 has a half-life of about 7.04 × 10 8 years; it is the next most stable uranium isotope after 238 U and is also predominantly an alpha emitter, decaying to thorium-231. [7] Uranium-235 is important for both nuclear reactors and nuclear weapons, because it is the only uranium isotope existing in nature on Earth in significant amounts ...
Uraninite crystals from Topsham, Maine (size: 2.7 × 2.4 × 1.4 cm) Uraninite is a major ore of uranium. Some of the highest-grade uranium ores in the world were found in the Shinkolobwe mine in the Democratic Republic of the Congo (the initial source for the Manhattan Project) and in the Athabasca Basin in northern Saskatchewan, Canada.
This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds.
A further 10 nuclides, platinum-190, samarium-147, lanthanum-138, rubidium-87, rhenium-187, lutetium-176, thorium-232, uranium-238, potassium-40, and uranium-235 have half-lives between 7.0 × 10 8 and 4.83 × 10 11 years, which means they have experienced at least 0.5% depletion since the formation of the Solar System about 4.6 × 10 9 years ...
Uranium-235 makes up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a fission chain reaction. It is the only fissile isotope that is a primordial nuclide or found in significant quantity in nature. Uranium-235 has a half-life of 703.8 million years.
In a fission nuclear reactor, uranium-238 can be used to generate plutonium-239, which itself can be used in a nuclear weapon or as a nuclear-reactor fuel supply. In a typical nuclear reactor, up to one-third of the generated power comes from the fission of 239 Pu, which is not supplied as a fuel to the reactor, but rather, produced from 238 U. [5] A certain amount of production of 239
Because radon is a product of the radioactive decay of uranium, underground uranium mines may have high concentrations of radon. Many uranium miners in the Four Corners region contracted lung cancer and other pathologies as a result of high levels of exposure to radon in the mid-1950s.
Technetium is a silvery-gray radioactive metal with an appearance similar to platinum, commonly obtained as a gray powder. [25] The crystal structure of the bulk pure metal is hexagonal close-packed. Atomic technetium has characteristic emission lines at wavelengths of 363.3 nm, 403.1 nm, 426.2 nm, 429.7 nm, and 485.3 nm. [26]