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Tritium

Tritium

Tritium is a radioactive isotope of hydrogen whose nucleus consists of a proton and two neutrons. The most important application of tritium is its use as a nuclear fuel for obtaining energy through nuclear fusion.

It is usually designated by the symbol T, although systematically it should be symbolized as 3H. It was discovered in 1934 by Rutherford, Oliphant and Harteck in the study of the bombardment of deuterium with deuterons.

Tritium is generated in the atmosphere in proportion to one atom for every 1017 of hydrogen, and is continuously formed to the upper atmosphere in nuclear reactions induced by cosmic rays. This isotope can be obtained industrially by lithium bombardment with low energy neutrons.

Tritium has a half-life of 12.4 years and emits very low energy β radiation (0.018 MeV), completely free of γ radiation, so it has practically no radiotoxicity. As regards chemical properties, tritium constitutes the exception to the general rule that the radioactive isotopes of an element behave analogously to their non- radioactive forms, due to the large difference in mass that it presents with respect to hydrogen. However, when it is incorporated into heavy molecules, this difference becomes insignificant, so that it is widely used in the labeling of molecules. It acts properly as a tracer, especially when replacing non-labile hydrogens.

Apart from being used to obtain energy through nuclear fusion, it is also used, to a lesser extent, for the preparation of luminous paints, apart from that already mentioned as a tracer.

Tritium radiation hazard

Tritium is a hydrogen isotope, which allows it to easily bind to hydroxyl radicals, forming tritiated water (HTO) and carbon atoms.

Tritium has a half-life (12.32 ± 0.02) years. In the tritium decomposition reaction, 18.59 keV of energy are released, of which 5.7 keV falls on the electron (beta particle) on average, and the rest on the antineutrino electron. The beta particles formed propagate in the air only 6.0 mm and cannot even overcome the upper layer of human skin.

Due to the low decomposition energy of tritium, emitted electrons can be easily stopped even by the simplest barriers, such as clothing or rubber surgical gloves. However, this isotope presents a radiation hazard when inhaled, absorbed with food and absorbed through the skin. The drinking action of drinking water contaminated with tritium once does not lead to a long-term accumulation of tritium in the body, since its half-life is 7 to 14 days.

Uses of Tritium

Tritium can be used in different applications with different objectives:

  • Self-powered lighting
  • Nuclear weapons
  • Controlled nuclear fusion
  • Analytic chemistry
  • Power source

Self-powered lighting

Beta particles emitted by the radioactive decay of small amounts of tritium cause chemicals called phosphors to shine. This radioluminescence is used in self-powered lighting devices called betalights, which are used for night lighting of firearms, watches, output signals, map lights, navigation compasses, knives and a variety of other devices.

Nuclear weapons

Tritium is an important component in nuclear weapons. It is used to improve the efficiency and performance of nuclear fission bombs and the fission stages of hydrogen bombs in a process known as reinforcement, as well as in external neutron initiators for such weapons.

Controlled nuclear fusion

Tritium is an important fuel for controlled nuclear fusion in nuclear fusion reactor designs by magnetic confinement and inertia. The ITER experimental fusion reactor and the National Ignition Facility (NIF) will use deuterium-tritium fuel. The deuterium-tritium reaction is favorable since it has the largest fusion cross section and reaches this maximum cross section with the lowest energy of any potential fusion fuel.

Analytic chemistry

Tritium is sometimes used as a radiolabel. It has the advantage that almost all organic chemicals contain hydrogen, so it is easy to find a place to place tritium in the molecule under investigation. It has the disadvantage of producing a relatively weak signal.

Power source

Finally, it is worth mentioning tritium as a source of electrical energy. Tritium can be used in a betavoltaic device to create an atomic battery to generate electricity.

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References

Last review: October 23, 2019