Isotopes of Hydrogen – Tritium is radioactive substance

Hydrogen (H) is the simplest atom (atomic number 1), is abundant, and has 1 protons and no neutrons. Two normal hydrogen atoms when combined with an oxygen atom create an ordinary (light) water molecule, or H2O. Every one knows about the uses of water.

Deuterium is another isotope of hydrogen with atomic mass of 2 (1 proton + 1 neutron). Unlike tritium, Deuterium is not radioactive. Two deuterium atoms combine with an oxygen atom to create Deuterium Oxide (D2O) or heavy water. Deuterium occurs naturally, for every 7,000 molecules of ordinary “light” water, there is one molecule of “heavy” water; approximately 100000 liters of ordinary water are needed to produce a single liter of pure heavy water. It is a very expensive procedure. India has mastered the heavy water production technology. Indian PHWR reactors use the heavy water (D2O) as the moderator and coolant.

Tritium is a radioactive form or isotope of hydrogen with atomic mass of 3 units (1 proton + 2 neutrons), with a radioactive half-life of 12.3 years and a biological half-life (the amount of time the body requires to excrete one half of the tritium absorbed) of about 10 days. Tritium decays to emit beta radiation of very low energy of 18.6 keV (kilo electron volt, maximum). The energy of tritium is not enough to penetrate human skin. Tritium is one of the least harmful radioactive substances. Comparatively, highly soluble Tritiated water is more harmful than tritium gas. The Annual Limit of Intake for tritiated water is 1 Giga Bq (Bq is the unit of activity; 1 Bq is the amount of radioactive material which decays at the rate of 1 disintegration per second). The decay product of tritium is 3He, an isotope of Helium, a non-radioactive noble gas.

Less than 1% of tritium occurs naturally (e.g. through the interaction of cosmic rays with molecules of certain elements in the upper atmosphere. Most of tritium is man made; fallout from thermonuclear weapons testing, begun in the 1940s, is a source of tritium in the global environment; nuclear power reactors, particularly of Indian type (PHWRs), are also a large source of tritium. Deuterium atom absorbs one more neutron in the nuclear reactor to form Tritium.

Tritium is used commercially as a light source in flares, emergency lights, exit signs and luminous dials (watches and clocks); tritium is also an essential fuel for experimental nuclear “fusion” and has been used for nuclear weapons production.