Uranium laser isotope separation

Laser isotope separation techniques have been demonstrated for many elements, including hydrogen, boron, carbon, nitrogen, oxygen, sHicon, sulfur, chlorine, titanium, selenium, bromine, molybdenum, barium, osmium, mercury, and some of the rare-earth elements. The most significant separation involves uranium, separating uranium-235 [15117-96-1], from uranium-238 [7440-61-1], (see Uranium and uranium compounds). The... 

Uranium enrichment using LIS has been exhaustively studied and the conceptual outlines of two different methods can be found in the open literature. These methods are multi-photon dissociation of UF6 (SILEX, or Separation of Isotopes by Laser Excitation) and laser excitation of monatomic uranium vapor (Atomic Vapor Laser Isotope Separation, or AVLIS). Following an enormous investment, AVLIS was used by the United States DOE in the 1980s and early 1990s, but due to the present oversupply of separated uranium, the plant has been shut down. 

Spectral Considerations in the Laser Isotope Separation of Uranium Hexafluoride," App, Phys., 1976, 10, 15. 

Accurate results of this type are needed for determining laser utilization in laser isotope separation of uranium. The application of this technique to obtain results for other elements would be useful in astronomy and plasma physics. 

Janes, G. S. Itzkan, I. Pike, C. T. Levy, R. H. and Levin, L.,"Two-Photon Laser Isotope Separation of Atomic Uranium Spectroscopic Studies, Excited-State Lifetimes, and Photoionization Cross Sections," IEEE, J. Quantum Electron, 1976, QE-12, 111-120. 

Davis, J. I. and Davis, R. W., "Some Aspects of the Laser Isotope Separation Program at Lawrence Livermore Laboratory," in "Developments in Uranium Enrichment, AIChE Symposium Series, V.73, No. 169" Benedict, M., Ed.,... 

This text can describe only briefly the incomplete information publicly available on laser separation of uranium isotopes. For a more detailed discussion of the history and principles of laser isotope separation, reference may be made to the review articles of Letokhov and Moore [LI] and Aldridge et al. [A2], and to Farrar and Smith s report on uranium [FI]. 

Laser Isotope Separation of Uranium Metal Vapor... 

History. In the United States, laser isotope separation (LIS) with uranium metal vapor has been investigated experimentally by the Lawrence Livermore Laboratory (LLL) of the U.S. DOE at Livermore, California, and by Jersey-Nuclear-Avco Isotopes, Inc. (JNAI), a joint venture of Exxon Nuclear Company of Bellevue, Washington, and Avco-Everett (Massachusetts) Research Laboratory, which holds a number of patents on this method, of which the most significant are those of Levy and Janes [Jl, L2]. 

Table 14.27. Estimated characteristics of uranium metal laser isotope separation plants...

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. 

Rao, P.R. (2003). Laser isotope separation of uranium— Research account, Curr. Res. 85, 615-632. 

The impetus for laser isotope separation studies is given by UFg. As mentioned in the previous section the presently known infrared lasers emit in the vicinity of 2.7 [xm (HF), 5 [xm (CO), and 10 [xm (CO2). Thus to employ the laser approach in uranium isotope separation requires the development of a new high-power, low-frequency, laser source since the V3 excitation mode used in the SFg experiments appears at 16.0 [xm in... 

When the first tunable dye lasers made their appearance late in the 1960s (see Stuke 1992), suggestions were put forward as to the use of resonance stepwise ionization for separating isotopes on the basis of isotope shifts in atomic spectra (Letokhov 1969). Following the first successful experiments on the selective ionization of Rb atoms and their isotopes (Ambartzumian et al. 1971), programs were initiated in a number of countries on laser separation of uranium isotopes ( U/ U) by a method that came to be known as the atomic-vapor-laser-isotope-separation (AVLIS) technique (Paisner... 

Experiments on the sky. Two experiments have been carried out at the sky, using two laser installations built for the American and French programmes for Uranium isotope separation, respectively AVLIS at the Lawrence Livermore Nat l Lab (California) in 1996 and SILVA at CEA/Pierrelatte (Southern France) in 1999. The average power was high pa 2 x 175 W, with a pulse repetition rate of 12.9 and 4.3 kHz, a pulse width of 40 ns and a spectral width of 1 and 3 GHz. Polarization was linear. The return flux was < 5 10 photons/m /s (Foy et al., 2000). Thus incoherent two-photon resonant absorption works, with a behavior consistent with models. But we do need lower powers at observatories ... 

Bradley reported that homoleptic uranium hexakis(alkoxide) complexes coordinated by secondary and tertiary alkoxides (U(OR)6 R = Pr , Bu , Bu ) were produced from thermal disproportionation of U0(0R)4 vide suprd) U(OMe)6 was initially prepared from oxidation of U (OMe)5 in the presence of benzoyl peroxide. Interest in a more convenient synthetic route to U(OMe)6 was stimulated by its potential use in uranium isotope separation, which can be achieved with a CO2 laser. Facile syntheses of U(OMe)6 were reported by different groups (see Equations (48) to (51)) ... 

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