A radioactive isotope of hydrogen having one proton and two neutrons in the nucleus. It decays spontaneously to Helium-3 by the emission of an electron (beta ray), with a half-life of 12.3 years. Symbol 1H3. Atomic weight 3.01605 (C-12 = 12.0000). It is one of the radioisotopes commonly used to label chemical compounds for use as tracers in biochemistry and chemistry. It is also used as one of the fusionable components of a hydrogen bomb.
The heaviest hydrogen isotope, containing one proton and two neutrons in the nucleus, produced most effectively by bombarding lithium-6 with neutrons. In a fission weapon, tritium produces excess neutrons, which set off additional reactions in the weapon's fissile material. In this way, tritium can either reduce the amount of fissile material required, or multiply (i.e., boost) the weapon's destructive power as much as five times. In fusion reactions, tritium and deuterium, another hydrogen isotope, bond at very high temperatures, releasing approximately 14 million electron-volts of energy per set of neutrons.