CANDU reactors typically produce 130 g of tritium per year, which is recovered at the Darlington Tritium Recovery Facility (DTRF). Ontario Power Generation's "Tritium Removal Facility" processes up to 2,500 tonnes (2,500 long tons 2,800 short tons) of heavy water a year, and it separates out about 2.5 kg (5.5 lb) of tritium, making it available for other uses. Even so, cleaning tritium from the moderator may be desirable after several years to reduce the risk of its escaping to the environment.
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This reaction has a quite small absorption cross section, making heavy water a good neutron moderator, and relatively little tritium is produced. Tritium is also produced in heavy water-moderated reactors whenever a deuterium nucleus captures a neutron. See also: Heavy water § Tritium production High-energy neutrons irradiating boron-10 will also occasionally produce tritium: 10Ī more common result of boron-10 neutron capture is 7Īnd a single alpha particle. This was discovered when the 1954 Castle Bravo nuclear test produced an unexpectedly high yield. High-energy neutrons can also produce tritium from lithium-7 in an endothermic (net heat consuming) reaction, consuming 2.466 MeV. For applications in proposed fusion energy reactors, such as ITER, pebbles consisting of lithium bearing ceramics including Li 2TiO 3 and Li 4SiO 4, are being developed for tritium breeding within a helium cooled pebble bed, also known as a breeder blanket. In comparison, the fusion of deuterium with tritium releases about 17.6 MeV of energy. The production of tritium from lithium-6 in such breeder ceramics is possible with neutrons of any energy, and is an exothermic reaction yielding 4.8 MeV.
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The release and diffusion of tritium and helium produced by the fission of lithium can take place within ceramics referred to as breeder ceramics. Tritium is most often produced in nuclear reactors by neutron activation of lithium-6. The low energy of tritium's radiation makes it difficult to detect tritium-labeled compounds except by using liquid scintillation counting. The unusually low energy released in the tritium beta decay makes the decay (along with that of rhenium-187) appropriate for absolute neutrino mass measurements in the laboratory (the most recent experiment being KATRIN). Beta particles from tritium can penetrate only about 6.0 mm of air, and they are incapable of passing through the dead outermost layer of human skin. The electron's kinetic energy varies, with an average of 5.7 keV, while the remaining energy is carried off by the nearly undetectable electron antineutrino. It decays into helium-3 by beta decay as in this nuclear equation:Īnd it releases 18.6 keV of energy in the process. While tritium has several different experimentally determined values of its half-life, the National Institute of Standards and Technology lists 4,500 ± 8 days ( 12.32 ± 0.02 years). Willard Libby recognized that tritium could be used for radiometric dating of water and wine. However, their experiment could not isolate tritium, which was accomplished in 1939 by Luis Alvarez and Robert Cornog, who also realized tritium's radioactivity. Deuterium is another isotope of hydrogen. Tritium was first detected in 1934 by Ernest Rutherford, Mark Oliphant and Paul Harteck after bombarding deuterium with deuterons (a proton and neutron, comprising a deuterium nucleus). 7.3.3 Tritium in hydrogen bomb secondaries.Tritium is also used as a nuclear fusion fuel, along with more abundant deuterium, in tokamak reactors and in hydrogen bombs. It is used in a medical and scientific setting as a radioactive tracer. Tritium is used as the energy source in radioluminescent lights for watches, gun sights, numerous instruments and tools, and even novelty items such as self-illuminating key chains. It can be artificially produced by irradiating lithium metal or lithium-bearing ceramic pebbles in a nuclear reactor, and is a low-abundance byproduct in normal operations of nuclear reactors. The atmosphere has only trace amounts, formed by the interaction of its gases with cosmic rays. Naturally occurring tritium is extremely rare on Earth. The nucleus of tritium ( t, sometimes called a triton) contains one proton and two neutrons, whereas the nucleus of the common isotope hydrogen-1 ( protium) contains just one proton, and that of hydrogen-2 ( deuterium) contains one proton and one neutron. Tritium ( / ˈ t r ɪ t i ə m/ or / ˈ t r ɪ ʃ i ə m/, from Ancient Greek τρίτος (trítos) 'third') or hydrogen-3 (symbol T or 3H) is a rare and radioactive isotope of hydrogen.