Heavy water . It is a somewhat heavier class of water (has a higher density) than common. A liter of heavy water weighs 1,105 grams, while a liter of ordinary water weighs 1,000 grams. Deuterium oxide is called heavy water (D2O).
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- 1 Chemical formula
- 2 Applications
- 3 Materials used for the production of heavy water
- 4 Properties in relation to common water
- 5 Methods of making heavy water
- 6 Lifespan of heavy water
- 7 Main producing plants
- 8 Sources
The chemical formula of deuterated water, deuterium oxide or heavy water is: D2O or 2H2O. The chemical formula for tritiated water, tritium oxide or super heavy water is: T2O or 3H2O. As already indicated, this form is radioactive. There are also other isotopic varieties such as: semi-heavy water whose chemical formula is HDO, DHO or 1H2H O. and an unnamed form that would correspond to a “semi-super heavy water”, sometimes called tritiated water, whose chemical formula is HTO, THO or 1H3H O. This form is radioactive. It is also extremely useful for neutrino detectors such as the kamiokande.
The main technological application of heavy water has been as a moderator in nuclear fission processes, which is why it became a strategic substance during the development of the first nuclear reactors. During World War II , the Allies undertook a set of direct actions to prevent Nazis from accessing heavy water (see Battle of Heavy Water). Today it has lost part of its importance, as other materials such as normal water or graphite are also used as moderators in nuclear power plants .
When natural uranium fuel is used in a reactor, only heavy water can fulfill the dual function of moderating neutrons and transferring the generated heat. Natural water, which has the same heat transmission capacity, produces such a high absorption of neutrons that it would prevent the chain reaction of this type of reactors from being maintained, being used only in enriched uranium reactors.
It is useful as a moderator and coolant in natural uranium reactors. Making heavy water is a challenge to technology. Argentina sought nuclear power plants of the natural uranium-heavy water type, thus seeking control of the fuel cycle. Considering the need to ensure the supply of heavy water, which is a critical input produced on an industrial scale by a very small number of countries, easily susceptible to international pressure, and in order to achieve technological independence in this field, The National Atomic Energy Commission resolved in a timely manner the execution of the Heavy Water Projects. There is a Heavy Water Plant in Arroyito (Neuquén), occupying an area of 20 hectares, along route 237, 50 km south of theNeuquén city , there an average of 200 tons of heavy water is produced / year.
Materials used for the production of heavy water
Theoretically, any compound that has hydrogen can be used , but given the low natural concentration of deuterium on an industrial scale, large volumes of raw material must be processed to obtain a reasonable production, so the most used raw materials are water and natural gas.
Properties in relation to common water
This difference in the elements of the core modifies some of its physical properties, such as density or boiling point. Heavy water is present, in small quantities, mixed with normal water, and can be separated from it by fractional distillation. It can also be separated from water by absorption with ammonia containing deuterium.
Heavy water brewing methods
Chemical exchange : also called isotopic exchange. Two phases are brought into contact, one liquid and the other gaseous, each one made up of a different hydrogenated compound (the gaseous phase can be directly hydrogen). Depending on the pressure and temperature conditions, a preferential accumulation of deuterium is obtained in one of the phases (generally the liquid phase), due to the fact that a hydrogen-deuterium exchange takes place between the different phases. Systems can be hydrogen / water, hydrogen / ammonia, hydrogen sulfide / water, hydrogen / methylamine. The PIAP uses the hydrogen / ammonia exchange method, taking natural water from the river as a source of deuterium.
Distillation : These methods are based on the small differences in vapor pressure between the deuterated and hydrogenated species (water, ammonia, and hydrogen). They are used to concentrate heavy water from water previously enriched by other methods to values of 10%.
Electrolysis : It is carried out by decomposition of water by means of an electric current. This method has high operating costs and requires the association of a plant that produces hydrogen for other uses. The first heavy water plant (Norway) used this method.
Heavy water life
Heavy water in a natural uranium reactor is considered a capital good, since when the nuclear power plant starts up the initial load is carried out and lasts for the entire operational life of the reactor. The annual need for heavy water in nuclear power plants is estimated to be around 1% of the initial inventory. These demands are due to small technical replacements that are produced by maintenance and normal operation tasks.
Main producing plants
- Argentina is the main producer and exporter, producing in a plant with a capacity of 200 t / year; It is located in Arroyito( Neuquen province ), operated by the state company ENSI.
- The United States produced heavy water until the 1980s.
- Canada was the world’s largest producer until the closure of the heavy water plant in 1997.
- Norway: The Norsk Hydro company opened the world’s first commercial production plant in 1934.
- India is the second largest heavy water producer through the Heavy Water Board.
- Romania produces heavy water at the Drobeta Girdler Sulfide plant and exports occasionally.
- France operated a small plant until 1970.
- United Kingdom: in 1958 itexported 20 t to Israel.