Glossary / Nuclear fusion
Deuterium
A heavy form of hydrogen with one proton and one neutron. It is not radioactive and is found in seawater.
In 1932 Harold Urey and colleagues found a very faint line right beside the spectral lines of hydrogen, showing that a hydrogen of about twice the mass exists[1]. Urey received the 1934 Nobel Prize in Chemistry for it. Roughly one in every 6,400 hydrogen atoms in water is deuterium.
It is the most basic fusion fuel. Since it can be extracted from seawater, supply is effectively unlimited. Deuterium can fuse with itself, but the D-T reaction with tritium happens far more readily, so most reactors under development use D-T. Experimental machines often run on deuterium alone, avoiding radioactive tritium.
Related terms
- TritiumA heavy form of hydrogen with one proton and two neutrons. It is weakly radioactive, almost absent in nature, and serves as fusion fuel.
- D-T fusionThe fusion of deuterium (D) and tritium (T) into a helium-4 nucleus and a neutron. Almost every fusion reactor now under development is built around this reaction.
- Nuclear fusionA reaction in which light atomic nuclei join to form a heavier one, releasing a large amount of energy. It is what makes the Sun and the stars shine.