Heavy Water

Heavy water, formally called deuterium oxide or 2H2O or D2O, is a form of water that contains the hydrogen isotope deuterium, rather than the common protium isotope. The colloquial term heavy water is often also used to refer a highly enriched water mixture that contains mostly deuterium oxide but also contains some ordinary water molecules as well: for instance heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction. In comparison, in ordinary water, there are only about 156 deuterium atoms per million hydrogen atoms).

Heavy water is not radioactive. In its pure form, it has a density about 11% greater than water, but otherwise, is physically and chemically similar. This difference in density (especially affecting the biological properties) is larger than in any other commonly occurring isotope-substituted compound because deuterium is unique among heavy stable isotopes in being twice as heavy as the lightest isotope. This difference increases the strength of water's hydrogen-oxygen bonds, and this in turn is enough to cause differences that are important to some biochemical reactions. The human body naturally contains deuterium equivalent to five grams of heavy water, which is harmless. When a large fraction of water (> 50%) in higher organisms is replaced by heavy water, the result is cell dysfunction and death.

Heavy water was first produced in 1932, a few months after the discovery of deuterium. With the discovery of nuclear fission in late 1938, and the need for a neutron moderator that captured few neutrons, heavy water became a component of early nuclear energy. Partly because of Nazi Germany's over-reliance on heavy water, not realizing that pure carbon could be used instead, it did not produce a functioning reactor for the duration of World War II. Since then, heavy water has been an essential component in some types of reactor, both those that generate power and those designed to produce isotopes for nuclear weapons, such as plutonium-239. These heavy water reactors have the advantage of being able to run on natural uranium without the use of graphite moderators which can pose radiological and dust explosion hazards in the decommissioning phase. Most modern reactors use enriched uranium and normal "light water" (H2O) moderator.

Read more about Heavy Water:  Physical Properties (with Comparison To Light Water), History, Effect On Biological Systems, Production

Other articles related to "heavy water":

Robert Döpel - Career - In Germany
... In August 1940, Döpel showed the utility of using heavy water as a moderator in a research nuclear reactor ("Uranmaschine") together with his wife Klara ... with a spherical geometry (hollow spheres) of uranium surrounded by heavy water ... in the first half of 1942, indicated that the spherical geometry, with five metric tons of heavy water and 10 metric tons of metallic uranium, could sustain a fission reaction ...
Leif Tronstad - World War II - Heavy Water Sabotage
... Already in 1941, Tronstad was aware that heavy water production at Vemork had greatly increased ... Tronstad had not been aware of the connection between heavy water and atomic weaponry, but it eventually became clear that Germany could be running a nuclear ... later learned from Jomar Brun that further expansion of heavy water production was being discussed ...
Leif Tronstad
... at the Norwegian Institute of Technology from 1936, he was also among the pioneers of heavy water research, and was instrumental when a heavy water plant was built at Vemork ... rocket and the growing German interest in heavy water ... Tronstad planned Operation Gunnerside, in which the German access to heavy water processing at Vemork was severely impeded ...
Leif Tronstad - Academic Career
... career, Tronstad penned about eighty scientific publications, including fourteen on heavy water-related topics ... The properties of heavy water had been discovered in 1932 by Harold Urey ... Norsk Hydro Rjukan, created a plan for industrial production of heavy water in Norway ...
Heavy Water - Applications - Tritium Production
... Some is created in heavy water moderated reactors when deuterium captures a neutron ... fluxes, or with a very high proportion of heavy water to nuclear fuel and very low neutron absorption by other reactor material ...

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