In deuterium–tritium fusion, one deuterium nucleus fuses with one tritium nucleus, yielding one helium nucleus, a free neutron, and 17.6 MeV, which is derived from approximately 0.02 AMUs.[1] The amount of energy obtained is described by the mass-energy relation: .
80% of the energy (14.1 MeV) becomes kinetic energy of the neutron traveling at 1⁄6 the speed of light.
The mass difference between D+T and neutron+4He is described by the semi-empirical mass formula that describes the relation between mass defects and binding energy in a nucleus.
About 1 in every 5,000 hydrogen atoms in seawater is deuterium, making it easy to acquire.[1][4]
Tritium, however, is a radioactive isotope, and difficult to source naturally. This can be circumvented by exposing the more readily available lithium to energetic neutrons, which produces tritium nuclei.[1][4] In addition, the deuterium–tritium reaction itself emits a free neutron, which can be used to bombard lithium.[5] A 'breeding blanket', which consists of lithium, is often placed along the walls of fusion reactors such that free neutrons created during deuterium–tritium fusion react with it to produce more tritium.[6][7] This process is called tritium breeding.
Deuterium–tritium fusion is planned to be used in ITER,[6] as well as many other proposed fusion reactors. It provides many advantages over other types of fusion, as it has a relatively low minimum temperature of 100 million degrees C.[8]