Isotope separation methods

Year of publication Bile acids assayed" Serum extraction Isotope Separation method Assay sensitivity (pmol/assay) Normal fasting serum cone, range (p.mol/liter) Reference... 

The IR multiphoton dissociation of CF3H, pre-excited to the second C-H stretch overtone, has been examined with a view to developing a laser isotope-separation method for C. This single stage process resulted in a C2F4 product... 

Some general conclusions regarding Isotope separation methods drawn by Manson Benedict (11) almost twenty years ago, have not been Invalidated to date by any direct experimental demonstration. 

National Defense Research Committee s early priorities were studies on radar, proximity fuzes, and anti-submarine warfare), the Uranium Committee recommended that isotope separation methods and the chain reaction work continue to receive funding for the remainder of 1940. Bush approved the plan and allocated the funds. 

O Equations (15.4) andO (15.5) show that the deflections of the ions of the lighter isotope are greater than those of the heavier isotope, provided that their velocities and charges are the same. The isotope analysis by mass spectrometry and the electromagnetic isotope separation method using large-scale mass spectrometers, called Calutrons because of their early development at the University of California Cyclotron Laboratory, are based on these effects. 

Lead (208) constitutes about 52% of most naturally occurring lead deposits, and is therefore abundant however, an economic isotope separation method is necessary to ensure the economic viability of utilizing lead (208) as a coolant.. There is also the potential for obtaining lead (208) from specific actinide decay chains for example the thoria chain yields essentially pure lead 208, although quantities are small. 

In natural uranium ores, the fraction of the atoms of the fissile isotope is about 0.72%. For many commercial applications, like production of fuel for light water reactors or several types of research reactors and other nuclear functions, its fraction must be increased, that is, isotope enrichment is carried ont. The main isotope separation methods, or isotope enrichment processes, ntilize the small differences in between the mass of U-235 and U-238. The two major commercial methods that have supplied most of the enriched uranium to date, gaseous diffusion and gas centrifuges, use the only gaseous compound of nraninm, nranium hexafluoride (UFg), as the feed material. Both methods utilize the difference between the mass of UFg (349 Da) and UFg (352 Da) where the mass ratio difference that is 0.86%. The product and tails of the enrichment process are also with the same chemical form, but the isotope composition of the material is altered in the enrichment process. Schematic diagrams of the principle of operation of these methods can be found on the web and in many textbooks, so will not be shown here. 

Finally, it should be noted that all the methods that rely on mass differaice, mass ratio, or kinetics to separate U-235 from U-238 will also lead to enrichment of U-234 (even to greater relative extent than U-235). Elevated levels of U-234 may complicate the utilization of the enrichment product. Similarly, use of reprocessed uranium that contains U-236 (and perhaps some U-232) may also affect the product quality. On the other hand, laser isotope separation methods will selectively enrich U-235 with only very slight changes in the U-234 and U-236 content. 

Based on established isotope uses, on the projected increase in the pollution problem, and on the apparent social and economic pressure for pollution abatement, a significant demand for enriched isotopes appears to be developing for the assessment and control of air, water, and soil pollutants. Isotopic techniques will be used in combination with conventional methods of detection and measurement, such as gas chromatography, x-ray fluorescence, and atomic absorption. Recent advances in economical isotope separation methods, instrumentation, and methodology promise to place isotopic technology within the reach of most research and industrial institutions. Increased application of isotope techniques appears most likely to occur in areas where data are needed to characterize the movement, behavior, and fate of pollutants in the environment. 

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