ABSTRACT
Small amounts of heavy water are not toxic, and some think that it would need perhaps 20-–25% of the water content of the body to be heavy water for serious poisoning to occur. It is like ordinary water, H2O, but the two hydrogen atoms are the ‘heavy hydrogen’ isotope, deuterium (D), which has a mass twice that of an ordinary hydrogen atom. In late 1938, the German scientists Otto Hahn and Friedrich ‘Fritz’ Strassmann found that uranium atoms could be split by slow neutrons, releasing energy, and more neutrons. They had discovered nuclear fission. Other scientists, including the Frenchman Jean Frederic Joliot-curie started working on this as well. Canada did use heavy water as the moderator in nuclear power plants, which used natural-abundance uranium. These days heavy water is obtained using the Girdler process, which employs an exchange reaction for which the equilibrium constant is very favorable.
