An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 12 Search : uranium
enriched uranium
  اورانیوم ِ پرداریده   
urânium-e pordâridé

Fr.: uranium enrichi   

Uranium in which the → proportion of the → isotope U-235 has been increased (above the 0.7% value in natural uranium).

enriched; → uranium.

natural uranium
  اورانیوم ِ زاستاری   
urâniom-e zâstâri

Fr.: uranium naturel   

Uranium as found in nature. It contains 0.7% uranium-235, 99.3% uranium-238, and a trace of uranium-234 by weight.

natural; → uranium.

transuranium element
  بن‌پار ِ ترا-اورانیومی   
bonpâr-e tarâ-urâniomi

Fr.: élément transuranien   

An element beyond uranium in the periodic table, with atomic number greater than 92. Such elements do not occur in nature, but may be obtained by suitable nuclear reactions. They are all radioactive and members of the actinide group.

trans-; → uranium; → element.

uranium
  اورانیوم   
urâniyom (#)

Fr.: uranium   

A → radioactive metallic → chemical element; symbol U. → Atomic number; → atomic weight 238.0289; → melting post 1,132 °C; → boiling point 3,818°C; → specific gravity 19.1 at 25 °C. Uranium has 14 known → isotopes of which 238U is the most abundant in nature. This isotope (→ half-life 4.5 billion years) is 138 times more abundant than 235U (half-life 710 million years). The metal was first isolated by the French chemist Eugène-Melchior Peligot in 1841. See also: → uranium oxide, → uranium conversion, → uranium dioxide, → uranium enrichment, → uranium hexafluoride, → uranium-233, → uranium-235, → uranium-238, → plutonium, → fissile isotope, → fertile isotope, → yellowcake.

From the name of the planet → Uranus. The German chemist Martin-Heinrich Klaproth discovered the element in 1789, following the German/English astronomer William Hershel's discovery of the planet in 1781.

uranium conversion
  هاگرد ِ اورانیوم   
hâgard-e urâniom

Fr.: convesrion de l'uranium   

A chemical process converting the → yellowcake to → uranium hexafluoride. The uranium hexafluoride is heated to become a gas and loaded into cylinders. When it cools, it condenses into a solid.

uranium; → conversion.

uranium dioxide
  دی‌اکسید ِ اورانیوم   
dioksid-e urâniyom

Fr.: dioxyde d'uranium   

A black crystalline solid (UO2pitchblende, carnotite, and autunite and is used chiefly as a source of nuclear energy by fission of the radioisotope uranium-235. After the → uranium hexafluoride is enriched, a fuel fabricator converts it into uranium dioxide powder and presses the powder into fuel pellets.

uranium; → dioxide.

uranium enrichment
  پُردارش ِ اورانیوم   
pordâreš-e urâniyom

Fr.: enrichissement de l'uranium   

The process by which the percentage of → fissile uranium in a sample is increased. Uranium obtained from mining contains several → isotopes of uranium in different compositions, such as U-238 (~99%), U-235 (~0.7%), and U-234 (~0.02%). Among them, U-235 is the only one that is fissile, i.e. can be used in a → nuclear reactor to produce heat (and consequently electricity) in a controlled manner. As such, the concentration of U-235 as a fuel used in a reactor needs to be increased, which is done using several techniques, such as → gaseous diffusion.

uranium; → enrichment.

uranium hexafluoride
  هگزافلویءورید ِ اورانیوم   
hegzâfluorid-e urâniyom

Fr.: hexafluorure d'uranium   

A white solid compound (UF6) of → uranium and → fluorine obtained by chemical treatment of → yellowcake, forming a vapor at temperatures above 56 °C. It contains both of the naturally occurring → isotopes of uranium U-235 and U-238. The isotopes are separated on the basis of differences in their diffusion properties. UF6 is the process medium for all separation processes for → uranium enrichment. It is essential that fluoride be a pure element and therefore solely the mass differences of U-235 and U-238 determine the separation process.

uranium; → hexa-; → fluoride.

uranium oxide
  اکسید ِ اورانیوم   
oksid-e urâniyom

Fr.: oxyde d'uranium   

A chemical compound made up of → uranium and → oxygen. The most common forms of uranium oxide are U3O8 and UO2. Both oxide forms are solids that have low solubility in water and are relatively stable over a wide range of environmental conditions. Triuranium octaoxide (U3O8) is the most stable form of uranium and is the form most commonly found in nature. → Uranium dioxide (UO2) is the form in which uranium is most commonly used as a → nuclear reactor fuel. At ambient temperatures, UO2 will gradually convert to U3O8.

uranium; → oxide.

uranium-233
  اورانیوم-۲۳۳   
urâniyom-233

Fr.: uranium-233   

A → fissile isotope bred by the → fertile isotope thorium-232. It is similar in weapons quality to → plutonium-239.

uranium.

uranium-235
  اورانیوم-۲۳۵   
urâniyom-235

Fr.: uranium-235   

The only naturally occurring → fissile isotope. Natural uranium has 0.7 percent of 235U; light water reactors use about 3 percent and weapons materials normally consist of 90 percent of this isotope.

uranium.

uranium-238
  اورانیوم-۲۳۸   
uranium-238

Fr.: uranium-238   

A → fertile isotope from which → plutonium-239 can be bred. It comprises 99.3 percent of natural uranium.

uranium.