isotope separation (redirected from Electromagnetic isotope separation)

isotope separation [′ī·sə‚tōp ‚sep·ə¦rā·shən]

(nucleonics)

The physical separation of different stable isotopes of an element from one another.

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Isotope separation

The physical separation of different isotopes of an element from one another. The different isotopes of an element as it occurs in nature may have similar chemical properties but completely different nuclear reaction properties. Therefore, nuclear physics and nuclear energy applications often require that the different isotopes be separated. However, similar physical and chemical properties make isotope separation by conventional techniques unusually difficult. Fortunately, the slight mass difference of isotopes of the same element makes separation possible by using especially developed processes, some of which involve chemical industry distillation concepts.

Isotope separation depends on the element involved and its industrial application. Uranium isotope separation has by far the greatest industrial importance, because uranium is used as a fuel for nuclear power reactors. The two main isotopes found in nature are ²³⁵U and ²³⁸U, which are present in weight percentages (w/o) of 0.711 and 99.283, respectively. In order to be useful as a fuel the weight percentage of ²³⁵U must be increased to between 2 and 5. The process of increasing the ²³⁵U content is known as uranium enrichment, and the process of enriching is referred to as performing separative work. See Nuclear fuels, Nuclear reactor

The production of heavy water is another example of isotope separation. Heavy water is obtained by isotope separation of light hydrogen (¹H) and heavy hydrogen (²H) in natural water. Heavy hydrogen is usually referred to as deuterium (D). All natural waters contain ¹H and ²H, in concentrations of 99.985 and 0.015 w/o, respectively, in the form of H₂O and D₂O (deuterium oxide). Isotope separation increases the concentration of the D₂O, and thus the purity of the heavy water.

The development of laser isotope separation technology provided a range of potential applications from space-flight power sources (²³⁸Pu) to medical magnetic resonance imaging (¹³C) and medical research (¹⁵O).

The isotope separation process that is best suited to a particular application depends on the state of technology development as well as on the mass of the subject element and the quantities of material involved. Processes such as electromagnetic separation, thermal diffusion, and the Becker Process which are suited to research quantities of material are generally not suited to industrial separation quantities. However, the industrial processes that are used, gaseous diffusion, gas centrifugation, and chemical exchange, are not suited to separating small quantities of material. See Centrifugation

Three experimental laser isotope separation technologies for uranium are the atomic vapor laser isotope separation (AVLIS) process, the uranium hexafluoride molecular laser isotope separation (MLIS) process, and the separation of isotopes by laser excitation (SILEX) process. The AVLIS process, which is more experimentally advanced than the MLIS and SILEX processes, exploits the fact that the different electron energies of ²³⁵U and ²³⁸U absorb different colors of light (that is, different wavelengths). AVLIS technology is inherently more efficient than either the gaseous diffusion or gas centrifuge processes. It can enrich natural uranium to ²³⁵U in a single step. In the United States, the AVLIS process is being developed to eventually replace the gaseous diffusion process for commercially enriching uranium. See Laser