Large scale isotope separation

AnXe species are known for fluorides of uranium, neptunium, and plutonium and for UCle. The hexafluorides are volatile compounds obtained by fluorinating Anp4. The highly volatile UFs is the compound used for the large-scale isotope separation of from UCle can be made by the reaction of AICI3 and UFe. The hexa-halides have octahedral geometry. 

A large scale isotope separation plant consists of a large number of separating units arranged in the form of an ideal (or no-mixing) cascade. An ideal cascade is sketched in Fig. 4. To differentiate the process... 

Oliphant, Shire, and Crowther, Proc. Roy. Soc., 1934, cxlvi, 922 this method was used later on the large scale to separate uranium isotopes. 

K. Cohen, The Theorg of Isotope Separation as Applied to Large Scale Production of235V, McGraw-HiU Book Co., Inc., New York, 1951. 

Electrolysis. For reasons not fiiUy understood (76), the isotope separation factor commonly observed in the electrolysis of water is between 7 and 8. Because of the high separation factor and the ease with which it can be operated on the small scale, electrolysis has been the method of choice for the further enrichment of moderately enriched H2O—D2O mixtures. Its usefiilness for the production of heavy water from natural water is limited by the large amounts of water that must be handled, the relatively high unit costs of electrolysis, and the low recovery. 

The need for a large number of stages and for the special equipment makes gaseous diffusion an expensive process. The three United States gaseous diffusion plants represent a capital expenditure of close to 2.5 x 10 dollars (17). However, the gaseous diffusion process is one of the more economical processes yet devised for the separation of uranium isotopes on a large scale. 

The extraction of deuterium from natural water feed forms an excellent case study of the application of large scale distillation and exchange distillation to isotope separation. The principal historical demand for deuterium has been as heavy water, D20, for use in certain nuclear reactors. Deuterium is an excellent neutron moderator, and more importantly, it has a low absorption cross section for slow neutrons. Therefore a reactor moderated and cooled with D20 can be fueled with natural uranium thus avoiding the problems of uranium isotope enrichment. This was the... 

The other major springboard for the fluorocarbon chemical industry was the "Manhattan Project to develop the atomic bomb. This required the large-scale production of highly corrosive elemental fluorine and uranium(VI) fluoride for the separation of the radioactive 235U isotope. Oils capable of resisting these materials were needed to lubricate pumps and compressors, and polymers were needed to provide seals. Peril uorinated alkanes and polymers such as PTFE and poly(chlorotrifluoroethylene) (PCTFE) proved to have the appropriate properties so practical processes had to be developed for production in the quantities required. In 1947 much of this work was declassified and was published in an extensive series of papers3 which described the fundamental chemistry on which the commercial development of various fluoro-organic products, especially fine chemicals, was subsequently based. 

CARRIER. (I) A neutral material such as dialomaceous earth used to support a catalyst in a large-scale reaction system. (2) A gas used in chromatography to convey the volatilized mixture to be analyzed over the bed of packing that separates the components. (3) An atomic tracer carrier a stable isotope or a natural element lo which radioactive atoms of the same element has been added for purposes of chemical or biological research. 

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