Isotope separation

Isotope separation is the generic name of methods with which the isotopes contained in a natural chemical element can be separated. It does not involve radioisotopes in the process.

By the separation process occurs practically not a pure isotope, but the method divides the original amount of fuel into two portions ( fractions), one of which is enriched in the other isotope of interest, and accordingly depleted. By multiple repetition of the procedure with the enriched subset, higher enrichment levels can be achieved.

The isotopes of the same element do not differ from each other in a chemical sense, almost. The isotope separation process therefore almost always based on physical processes. Exceptions there are only very light elements such as hydrogen and lithium, where the relative difference in mass of the atoms is so large that it makes itself felt in the chemical behavior.

Method

For isotope separation, the following procedure can be applied:

  • Mass spectrometry ( for analytical purposes )
  • Centrifugation with gas centrifuges
  • Gas diffusion method according to the membrane process
  • Separation nozzle method
  • Fractional distillation (eg mercury isotopes, heavy water)
  • Electrolysis (eg enrichment of deuterium)
  • Photochemically on selective excitation of isotopes in a mixture with laser light, the excited isotopes are more reactive and can be removed by subsequent reactions.

Applications

The quantitatively most important by far is the separation of isotopes of uranium enrichment, increasing the content of uranium -235, for the production of nuclear fuel for nuclear power plants. For nuclear weapons purposes and lithium of lithium -6 is enriched. For nuclear fusion reactors for the duration also enriched lithium will be required to the fusion fuel erbrüten tritium in the blanket. Here the separation of the hydrogen isotopes protium, deuterium and tritium from each other is necessary.

Further applications of ( almost) pure isotopes or isotopically enriched materials are available for research purposes. Under the Avogadroprojektes highly enriched silicon 28 is used for the manufacture of mass standards.

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