Heavy water tritium

DEUTERIUM. The isotope of hydrogen having an atomic mass of two. Ordinary hydrogen has one electron, one proton, and a mass of one, whereas deuterium has one electron, one proton, and one neutron. Deuterium is a stable isotope, meaning that it does not undergo decay and is not radioactive. See also HEAVY WATER TRITIUM. 

DifficultSepa.ra.tions, Difficult separations, characterized by separation factors in the range 0.95 to 1.05, are frequentiy expensive because these involve high operating costs. Such processes can be made economically feasible by reducing the solvent recovery load (260) this approach is effective, for example, in the separation of m- and -cresol, Hnoleic and abietic components of tall oil (qv), and the production of heavy water (see Deuteriumand TRITIUM, deuterium). 

Tritium is produced in heavy-water-moderated reactors and sometimes must be separated isotopicaHy from hydrogen and deuterium for disposal. Ultimately, the tritium could be used as fuel in thermonuclear reactors (see Fusionenergy). Nuclear fusion reactions that involve tritium occur at the lowest known temperatures for such reactions. One possible reaction using deuterium produces neutrons that can be used to react with a lithium blanket to breed more tritium. 

Thermodynamic Properties. Ordinary water contains three isotopes of hydrogen [1333-74-0] (qv), ie, H, H, and H, and three of oxygen [7782 4-7] (qv), ie, O, and The bulk of water is composed of and O. Tritium [15086-10-9] H, and are present only in extremely minute concentrations, but there is about 200-ppm deuterium [16873-17-9], H, and 1000-ppm in water and steam (see Deuterium and tritium). The thermodynamic properties of heavy water are subtly different from those of ordinary water. lAPWS has special formulations for heavy water. The properties given herein are for ordinary water having the usual mix of isotopes. 

Production in Target Elements. Tritium is produced on a large scale by neutron irradiation of Li. The principal U.S. site of production is the Savaimah River plant near Aiken, South Carolina where tritium is produced in large heavy-water moderated, uranium-fueled reactors. The tritium may be produced either as a primary product by placing target elements of Li—A1 alloy in the reactor, or as a secondary product by using Li—A1 elements as an absorber for control of the neutron flux. 

Production in Heavy Water Moderator. A small quantity of tritium is produced through neutron capture by deuterium in the heavy water used as moderator in the reactors. The thermal neutron capture cross section for deuterium is extremely small (about 6 x 10 consequendy the... 

Heavy water [11105-15-0] 1 2 produced by a combination of electrolysis and catalytic exchange reactions. Some nuclear reactors (qv) require heavy water as a moderator of neutrons. Plants for the production of heavy water were built by the U.S. government during World War II. These plants, located at Trad, British Columbia, Morgantown, West Virginia, and Savaimah River, South Carolina, have been shut down except for a portion of the Savaimah River plant, which produces heavy water by a three-stage process (see Deuterium and tritium) an H2S/H2O exchange process produces 15% D2O a vacuum distillation increases the concentration to 90% D2O an electrolysis system produces 99.75% D2O (58). 

It is rare and found in "heavy" water (DOD), and it is present as only one part in almost 7,000 parts of regular water. Tritium ( T or H-3), another variety of heavy water (TOT), has nuclei consisting of one proton and two neutrons. It is man-made by nuclear reactions and is radioactive. 

Starting with the atmospheric thermonuclear tests, tritium concentration in the Northern Hemisphere has increased considerably above the natural background of approximately 10 pCi/liter of water (5). Since the cessation of these tests, environmental tritium concentrations have decreased gradually. Tritium is, however, produced in every nuclear reactor to some extent as a product of fission (1) or the activation of deuterium. In particular, reactors with heavy water as the moderator or cooling agent produce a large amount of tritium. Inasmuch as no... 

Heavy water - [NUCLEARREACTORS - ISOTOPE SEPARATION] (Vol 17) -use m tritium production [DEUTERIUM AND TRITIUM - TRITIUM] (Vol 8)... 

Deuterium is abundant, naturally occurring and in wide use now as D20 in heavy-water-mo derated reactors. Tritium is a radioactive isotope with a 12.3-year half-life and does not occur in natnre. Tritium emits an electron and decays to stable helium-3. 

Plutonium-239 and tritium for use as military explosives are the two major transmutation products. The nuclear process for Pu-239 production is the same as for energy generation, but there are some differences (a) metallic natural uranium clad with aluminum facilitates later dissolution for plutonium recovery, and the reactor operates at a relatively low temperature because of the aluminum clad and better heat transfer (due to the metallic natural uranium) (b) the irradiation cycle is limited to a few months to minimize the Pu-239 conversion to Pu-240 and Pu-241 and (c) a carbon or a heavy water moderator is used to increase the neutron efficiency. 

A number of isotopically different forms of water can be prepared, which greatly facilitates experimental studies. Replacing both of the usual hydrogen atoms with deuterium (2H) results in heavy water, or deuterium oxide, with a molecular weight of 20. The role of water in chemical reactions can then be studied by analyzing the deuterium content of substances involved as reactants or products. Tritium (3H), a radioactive isotope with a half-life of 12.4 years, can also be incorporated into water. Tritiated water has been used to measure water diffusion in plant tissues. Another alternative for tracing the pathway of water is to replace the usual 160 isotope with lsO. This labeling of water with lsO helped determine that the O2 evolved in photosynthesis comes from H20 and not from CO2 (Chapter 5, Section 5.5A). 

Grosse etal measured highly concentrated heavy water samples produced from surface waters that contained concentrations of natural tritium approximately one million times higher than the original water. Observations have shown that concentrated samples are indeed radioactive to a level corresponding to a natural abundance of tritium of about 10 by atomic ratio. 

Use Moderator in some types of nuclear reactors. Tritium (hydrogen of atomic weight 3) combines with oxygen to give another variety of heavy water, TOT, i.e., tritium oxide. 

The deuteron and triton are the nuclei of two isotopes of hydrogen, called deuterium and tritium. Deuterium occurs naturally in water. When the D2O is purified as heavy water, it can be used for several types of chemical analysis. 

D2O is also an excellent coolant and as both moderator and coolant, it is not consumed, but does get downgraded and leaks out of the system. Fortunately, these losses are manageable. A few neutrons, captured by D2O in the reactor, result in the formation of tritium, which exists in the form of DTO and presents hazards in the handling irradiated heavy water. ... 

D2O-DT exchange can be used for transferring tritium from heavy water to deuterium. Further enrichment is achieved by cryogenic distillation. Because of the similarity between deuterium and tritium, platinum on charcoal is the catalyst for vapor phase exchange, whereas hydrophobic catalyst is used for liquid-gas exchange. 

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