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Related to heavy water: light water
Either of two isotopic forms of water, especially deuterium oxide, consisting chiefly of molecules that contain deuterium instead of protium. Heavy water is used as a moderator in certain nuclear reactors.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Elements & Compounds) water that has been electrolytically decomposed to enrich it in the deuterium isotope in the form HDO or D2O
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
water in which hydrogen atoms have been replaced by deuterium, used as a nuclear reactor coolant.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
Water formed of oxygen and deuterium. Heavy water is much like ordinary water but has higher freezing and boiling points. It is used in certain nuclear reactors for cooling.
Did You Know? How can one drop of water be heavier than another? The answer lies at the atomic level. Normal hydrogen has a nucleus consisting entirely of one proton, around which whirls one electron. However, in a variety of hydrogen called heavy hydrogen or deuterium, a neutron accompanies the proton in the nucleus. Deuterium thus weighs about twice as much as standard hydrogen. The substance we call heavy water is H2O in which many of the hydrogen atoms are replaced by deuterium. Heavy water played a part in the development of the atomic bomb during World War II. It is an excellent absorber of the neutrons that are produced in large quantities in a nuclear chain reaction. It therefore provided a means of regulating the reactions so that they could be studied safely. Once it was shown that a controlled chain reaction was possible, making a device that could create a powerful uncontrolled chain reaction—an atomic bomb—seemed within reach. Heavy water is still found today in nuclear power plants that use natural uranium fuel.
The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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|Noun||1.||heavy water - water containing a substantial proportion of deuterium atoms, used in nuclear reactors|
moderator - any substance used to slow down neutrons in nuclear reactors
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