Tritium is the heaviest of the three hydrogen isotopes, with a nucleus having two neutrons and a proton. Tritium does not occur in Nature, since it is radioactive with a half-life of 12,3 years. However, tritium can be found around the Sun and probably through the space as a result of interstellar matter bombardment by cosmic rays.
This isotope can be produced through the nuclear bombardment of deuterium by hydrogen, or through the reaction of thermal neutrons with lithium-6 in nuclear reactors. It is commercially available in the solution form.
Tritium is mainly used as an hydrogen substitute in reactions, in order to study the process mechanisms or to identify and analyze products. This substitution makes the compounds radioactive (and heavier), making the monitoring of its presence and concentration an easier task, with radiation detectors.