All articles starting with U

Uranium series

The uranium series is the radioactive decay chain of uranium-238, passing through thirteen radioactive daughters before reaching stable lead-206. It supplies most natural radioactivity in the environment, including radon-222.

Uranium silicide

Uranium silicide, mainly the compound U3Si2, is a high-density nuclear fuel used in aluminum-matrix research reactor plates and tested as an accident tolerant light water reactor fuel.

Uranium tetrafluoride

Uranium tetrafluoride (UF4), known as green salt, is a green crystalline solid of uranium in the +4 oxidation state, the key intermediate between uranium oxide and uranium hexafluoride.

Uranium trioxide

Uranium trioxide (UO₃) is the highest oxide of uranium, in which uranium is in the +6 oxidation state, and serves as a high-purity intermediate in uranium refining.

Uranium-233

Uranium-233 is a fissile artificial isotope of uranium with a half-life of about 160,000 years, bred from natural thorium-232 by neutron capture and used as a nuclear reactor fuel.

Uranium-235

Uranium-235 is a naturally occurring uranium isotope making up 0.72% of natural uranium, and the only one that can sustain a nuclear chain reaction with slow neutrons.

Uranium-238

Uranium-238 is the most abundant uranium isotope, making up 99.27% of natural uranium, with a half-life of about 4.5 billion years, close to the age of the Earth.

Uranium-plutonium-zirconium metal fuel

Uranium-plutonium-zirconium metal fuel (U-Pu-Zr) is a ternary metallic alloy nuclear fuel, developed at Argonne National Laboratory as the driver fuel for the Integral Fast Reactor.

Uranium-zirconium alloy

Uranium-zirconium alloy, or U-Zr, is a metallic nuclear fuel, usually uranium with 10 weight percent zirconium, valued for high thermal conductivity and use in sodium-cooled fast reactors like EBR-II.

Uranium-zirconium hydride

Uranium-zirconium hydride (UZrH) is a nuclear fuel combining uranium metal and a zirconium hydride moderator, developed by General Atomics in 1957 for the TRIGA research reactors.

Uranium–lead dating

Uranium–lead dating, or U–Pb dating, is a radiometric method that determines the age of geological materials from uranium's decay to lead, most reliably applied to zircon crystals.

Uranium–thorium dating

Uranium–thorium dating (U-series, 230Th/234U dating) is a radiometric method dating carbonates like speleothems and corals up to about 640 ka, assuming a closed system and no initial thorium, with ~1% precision and radiocarbon cross-checks.

Sep 29, 2026

Uranium–thorium–helium thermochronology

Uranium–thorium–helium ((U-Th)/He) thermochronology is a geochronology method dating minerals by radiogenic helium from uranium and thorium decay, used to study exhumation, fault slip, and landscape evolution.

Uranium–uranium bond

A uranium–uranium bond is a direct chemical bond between two uranium atoms, detected in gas-phase U2 and proposed inside fullerene cages, but never realized in an isolable compound.

Uranium(II) metallocene

Uranium(II) metallocenes are sandwich compounds with uranium in the rare +2 oxidation state between two cyclopentadienyl-type ligands; the linear [U(η⁵-C₅ⁱPr₅)₂], reported in 2019, is the best-studied example.

Uranium(II) sandwich complex

A uranium(II) sandwich complex is an organometallic uranium compound with uranium in the rare +2 oxidation state between two π ligands; the first example was reported in 2020.

Uranium(VI) terminal nitride

A uranium(VI) terminal nitride is a molecular complex with a nitride ligand bound by a formal uranium–nitrogen triple bond to a single uranium(VI) center, uncapped by any bridging atom.

Uranius Dorsum

Uranius Dorsum is a 542-km-long ridge on Mars on the northwest edge of Kasei Valles, IAU-named in 1985 for an albedo feature, a Hesperian chain of 58 aligned cratered cones of uncertain origin.

Uranius Fossae

Uranius Fossae: IAU-named (1985) graben system on Mars, about 394 km across near 25.3°N, 269.9°E, east of Uranius Mons; multidirectional cross-cutting graben in old Noachian-Hesperian terrain.

Uranius Mons

Uranius Mons is a 274-km-diameter shield volcano in northeast Tharsis, Mars, at 26.83°N, 267.80°E, about 4.8 km high with a summit caldera, the northern end of the Tharsis Montes axial trend, distinct from nearby Uranius Patera and Uranius Tholus.

Uranius Patera

Uranius Patera is a low, broad shield volcano in northeast Tharsis, Mars, part of the Uranius group with Uranius Tholus and Ceraunius Tholus; Late Hesperian basaltic shield, 3 km relief, large 110 by 90 km caldera.

Oct 20, 2026

Uranotaenia

Uranotaenia (Heaven Mosquito) is a genus of small culicine mosquitoes, sole genus of tribe Uranotaeniini, with about 276 species in subgenera Pseudoficalbia and Uranotaenia; Ur. sapphirina uniquely feeds on annelids.

Uranus

Uranus is the seventh planet from the Sun, an ice giant tipped on its side, discovered by William Herschel in 1781 and visited once by Voyager 2 in 1986.

Uranus (mythology)

Uranus (Ancient Greek: Οὐρανός, Ouranos), known to the Romans as Caelus, is the primordial Greek god of the sky, castrated by his son Cronus and father by Gaia of the Titans, Cyclopes, and Hundred-Handers.

Uranus 2324

Uranus 2324 (ยูเรนัส 2324) is a 2024 Thai sci-fi romance GL film, Thailand's first space movie, directed by Thanadol Nualsuth, starring Freen Sarocha Chankimha and Becky Armstrong as an astronaut and free diver reunited across parallel worlds; released 4 July 2024.