Tritium

Tritium is a radioactive isotope of hydrogen, denoted as hydrogen-3 (³H). It contains one proton and two neutrons in its nucleus, making it heavier than the more common isotopes of hydrogen, which include protium (¹H) with one proton and deuterium (²H) with one proton and one neutron. Tritium is produced naturally in the atmosphere through the interaction of cosmic rays with atmospheric gases, and it can also be manufactured in nuclear reactors.

Tritium is notable for its use in various applications, including in nuclear fusion reactions, where it acts as a fuel alongside deuterium. It is also used in self-luminous devices, such as exit signs and watch dials, where it provides a low-level glow due to its beta decay emissions. Tritium has a half-life of approximately 12.32 years, meaning it decays relatively slowly compared to other radioactive materials. Safety measures are important when handling tritium, despite its low radiation hazard compared to more radioactive substances.