A radioactive isotope of hydrogen having an atomic weight of 3.02 and a half-life of 12.3 years. Its nucleus is called a triton and consists of one proton and two neutrons. It decays by beta decay and is used in thermonuclear bombs, thermonuclear fusion devices, as a radioactive tracer, etc. Tritium occurs in natural water with an abundance 10^-18 that of ordinary hydrogen.

Tritium was discovered in 1934 by the physicists Ernest Rutherford, M. L. Oliphant, and Paul Harteck by bombarding deuterium with high-energy deuterons. Tritium is produced most effectively by the nuclear reaction between lithium-6 and neutrons from nuclear fission reactors.

Symbol: T