Heavy water production processes

Table V. Process Variables for Heavy Water Production Processes...

Benedict, M., Survey of Heavy Water Production Processes, Conference, Switzerland, 30 June, 1955... 

Benedict, M., "Survey of Heavy Water Production Processes". Pioc. Int l Conf. on Peaceful Uses of Atomic Energy, (19561, 8, 577, Uhlted Nations, N. Y. 

The recognition in 1940 that deuterium as heavy water [7789-20-0] has nuclear properties that make it a highly desirable moderator and coolant for nuclear reactors (qv) (8,9) fueled by uranium (qv) of natural isotopic composition stimulated the development of industrial processes for the manufacture of heavy water. Between 1940 and 1945 four heavy water production plants were operated by the United States Government, one in Canada at Trail,... 

Table 8.4 Possible processes for heavy water production (Rae, H. K., Ed., Separation of hydrogen isotopes, ACS Symp. Ser. 68, 134 (1978)) ...

Sadhankar, R.R. and Miller, A.I, New heavy water production and processing technologies, 3rd Conference Isotopic and Molecular Processes PIM2003, Sep. 25-27, 2003, Cluj-Napoca, Romania, 2003. 

Utility requirements reported for heavy-water production by the GS process are as follows ... 

Heavy-water production in Canada began on a small scale in a plant operated by Cominco for the United States Atomic Energy Commission (USAEC) in 1944 (14) and continued until 1956. This was also a period of initial research into heavy-water processes at CRNL (15). By the mid-1950 s the USAEC and the E. I. Dupont de Nemours and Company had put into operation two large, heavy-water plants using the GS process. The... 

O Table 51.7 contains a partial list of possible processes for heavy water production. Distillation, while the simplest, is prohibitively expensive (except for low-temperature... 

These condensates come from thermal or hydrogen cracking operations where carrier steam is used in injection or aeration. The heavy viscous products processed are rich in sulfur which is hydrogenated and carried off by the steam. Demineralized water may also be added upstream from the FCC to decrease the H2S and NH3 partial pressures in the steam and carry off these gases by dissolving them (Fig. 10b). 

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). 

Tar sand, also variously called oil sand (in Canada) or bituminous sand, is the term commonly used to describe a sandstone reservoir that is impregnated with a heavy, viscous black extra heavy cmde oil, referred to as bitumen (or, incorrectly, as native asphalt). Tar sand is a mixture of sand, water, and bitumen, but many of the tar sand deposits in the United States lack the water layer that is beHeved to cover the Athabasca sand in Alberta, Canada, thereby faciHtating the hot-water recovery process from the latter deposit. The heavy asphaltic organic material has a high viscosity under reservoir conditions and caimot be retrieved through a weU by conventional production techniques. 

In the heavy-water plants constmcted at Savannah River and at Dana, these considerations led to designs in which the relatively economical GS process was used to concentrate the deuterium content of natural water to about 15 mol %. Vacuum distillation of water was selected (because there is Httle likelihood of product loss) for the additional concentration of the GS product from 15 to 90% D2O, and an electrolytic process was used to produce the final reactor-grade concentrate of 99.75% D2O. 

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). 

The facilities at Savannah River(j)) consist of five heavy-water-moderated and cooled production reactors, two chemical separations areas as a heavy water extraction plant, several test reactors, reactor fuel and target processing facilities, the Savannah River Laboratory, and many other facilities necessary to support the operations. During the 1960 s, two of the... 

A process involving water electrolysis is the production of heavy water. During cathodic polarization the relative rates of deuterium discharge and evolution are lower than those of the normal hydrogen isotope. Hence, during electrolysis the solution is enriched in heavy water. When the process is performed repeatedly, water with a D2O content of up to 99.7% can be produced. Electrochemical methods are also used widely in the manufacture of a variety of other inorganic and organic substances. 

Figure 21.2 shows the entire low-temperature process in block flow format. Following the reactor and cooler, the liquid EDC is washed, removing unreacted chlorine and catalyst. Product EDC is obtained in two distillation steps drying, where water and a small amount of light by-products are removed and purification, which removes a small amount of heavy by-products. Both of these distillation steps use steam-heated reboilers. 

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