Chemistry: electrical and wave energy – Processes and products – Processes of treating materials by wave energy
Patent
1994-09-21
1997-01-07
Mai, Ngoclan
Chemistry: electrical and wave energy
Processes and products
Processes of treating materials by wave energy
42218603, 250423P, B01D 500
Patent
active
055919472
DESCRIPTION:
BRIEF SUMMARY
The discovery of a method and the invention of a system for obtaining high selectivity with very high dissociation yield in the Molecular Laser Isotope Separation (MLIS) route of Uranium Hexafluoride (UF.sub.6) are described. The system described here will improve the efficiency (by greatly increasing the selectivity and dissociation yield) and minimize the capital and maintenance costs of the molecular laser isotope separation method by enormous factors.
It had generally been accepted in the past that for a commercial separation plant the Uranium Hexafluoride (UF.sub.6) is the most attractive gas for the enrichment of Uranium and the Molecular Laser Isotope Separation (MLIS) is the most desirable process. The technoeconomics of the molecular route (MLIS) for commercially separating the UF.sub.6 isotopes can be grouped into two main areas: (i) The performance of the laser systems and their capital and maintenance cost; (ii) The efficient use of photons in the selectivity and dissociation process.
In the past it has been estimated that the capital and maintenance cost of the laser systems would amount for half of the total expenditure (e.g. Los Alamos Science report on isotope separation 1982). My parallel International patent application based CB 9111310.0 describes an extremely simple laser system which fulfils all the technological requirements for the MLIS method in terms of efficiency, performance and output characteristics, and in addition its capital and maintenance costs are extremely small. This very simple laser system could make the MLIS method more efficient than the AVLIS method on its own.
The second area concerning the commercial realization of the MLIS method is the efficiency of the process of interaction which has hitherto run into certain problems because of the poor selectivity obtained between the UF.sub.6 isotopes when high laser pumping powers are used. A method for obtaining high dissociation yield in a single highly selective step in the Molecular Laser Isotope Separation (MLIS) process is embodied in the present invention and it is described with reference to FIGS. 1-9:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the spectrum of the expansion supercooled UF.sub.6 molecular gas enriched to 3% in .sup.235 UF.sub.6.
FIG. 2 shows the density of the vibrational states of various polyatomic molecules as a function of vibrational energy.
FIG. 3a shows the standard Raman scattering process and FIG. 3b shows the spectrum of the Stokes and Antistokes frequencies with the higher orders of Stokes radiation appearing simultaneously i.e. having approximately the same threshold.
FIG. 4 shows a schematic set-up for the application of perpendicularly crossed sets of beams to the UF.sub.6 molecular gas.
FIG. 5a shows an arrangement for .sup.235 UF.sub.6 large dissociation yield in a single highly selective step and FIG. 5b depicts the equivalence of the Mach-Zehnder interferometer principle to the arrangement of FIG. 5a with the molecular gas placed in the position of the reuniting beamsplitter.
FIG. 6a shows a schematic set-up for Uranium Hexafluoride (UF.sub.6) isotope separation based on the arrangement of FIG. 5a, and FIG. 6b shows a repetition of the arrangement of FIG. 6a along the direction of expansion of the molecular gas, the positions marked .sym. being those where the two sets of pumping beams cross each other perpendicularly, the system allowing for a completely uniform and efficient illumination of the UF.sub.6 supercooled gas.
FIG. 7a shows a vibrational ladder with .omega..sub.mn +.omega..sub.nl =.omega..sub.ml and FIG. 7b shows the experimental dependence of the two frequency dissociation yield (=fluorescence) on the CO.sub.2 frequency .omega..sub.2.
FIG. 8 shows how a .sup.235 UF.sub.6 molecule will be excited through the lower vibrational levels and thereafter to dissociation by absorption of radiation at .omega..sub.1 =.omega..sub.0, .omega..sub.2 =.omega..sub.0 +.omega..sub.12 and .omega..sub.12 =.omega..sub.2 -.omega..sub.1, when two frequencies .omega..sub.1 and .omega..
REFERENCES:
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"Spectral Dependence of Excitation of High Vibrational Levels in a Uranium Hexaflouride Molecule", Alimpiev et al, Chemical Abstracts, vol. 97, No. 24, Dec. 13, 1982, p. 493.
"Uranium Hexaflouride Photodissociation Through Measurement of Visible and Infrared Luminescence", Oyama et al., Chemical Abstracts, vol. 105, No. 8, Aug. 25, 1986, p. 619.
Mai Ngoclan
Synergetic Resiurces Limited
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