Uranium and its applications

Uranium plays one of the important roles in nuclear fuel, uranium-238 is converted into fissionable plutonium by the following reactions: 238U (n, gamma) --> 239U -- (beta) --> 239Np -- (beta) --> 239Pu. This nuclear conversion will be brought about in breeder reactors where it is possible to produce more and more new fissionable material than the fissionable material used in maintaining the chain reaction.

Uranium-235 is even greater importance because it is the key to utilize the uranium. While 235U is occurring in natural uranium to the extent of only 0.71%, is so fissionable with slow neutrons that a self-sustaining fission chain reaction can be made in a reactor constructed from natural uranium and a suitable moderator, such as heavy water or graphite, alone.

Uranium-235 can be concentrated by gaseous diffusion and other physical processes, if preferred, and used directly as a nuclear fuel, instead of natural uranium, or can be used as an explosive.

Natural uranium, lightly enriched with 235U by a small percentage, is used to fuel nuclear power reactors to generate the electricity. Natural thorium can be irradiated with neutrons as follows to make the important isotope 233U: 232Th (n, gamma) --> 233Th -- (beta) -> 233Pa -- beta) --> 233U. While thorium itself is not fissionable one, but, 233U is, and can be used as a nuclear fuel. One pound of completely fissionable uranium has the fuel value of over 1500 tons of coal.

The uses of nuclear fuels to produce the electrical power, to make isotopes for peaceful purposes, and to make explosives are well known. The predictable world-wide capacity of the 429 nuclear power reactors in operation in January 1990 amounted to about 311,000 megawatts.

In U.S.A. uranium is controlled by the U.S. Nuclear Regulatory Commission. Further more uses are being found for depleted uranium, i.e., uranium with the percentage of 235U lowered to about 0.2%.

Uranium is also used in inertial guidance devices, in gyro compasses, as counter weights for aircraft control surfaces, as ballast for missile reentry vehicles, and as a shielding material. Uranium metals are used for X-ray targets for the production of high-energy X-rays; the nitrate was once used as a photographic toner, and the acetate was once used in analytical chemistry.

Crystals of uranium nitrate are also triboluminescent. Uranium salts have been used for producing the yellow "Vaseline" glass and glazes and its compounds are highly toxic, both from a chemical and radiological standpoint.