Actinides, separation

The elucidation of actinide chemistry in solution is important for understanding actinide separation and for predicting actinide transport in the environment, particularly with respect to the safety of nuclear waste disposal.72,73 The uranyl CO + ion, for example, has received considerable interest because of its importance for environmental issues and its role as a computational benchmark system for higher actinides. Direct structural information on the coordination of uranyl in aqueous solution has been obtained mainly by extended X-ray absorption fine structure (EXAFS) measurements,74-76 whereas X-ray scattering studies of uranium and actinide solutions are more rare.77 Various ab initio studies of uranyl and related molecules, with a polarizable continuum model to mimic the solvent environment and/or a number of explicit water molecules, have been performed.78-82 We have performed a structural investigation of the carbonate system of dioxouranyl (VI) and (V), [U02(C03)3]4- and [U02(C03)3]5- in water.83 This study showed that only minor geometrical rearrangements occur upon the one-electron reduction of [U02(C03)3]4- to [U02(C03)3]5-, which supports the reversibility of this reduction. 

Fission products and actinides in spent nuclear fuels have also been analyzed using cation-exchange LC [98]. Chromatography was essential in order to separate fission Cs from Ba for the analysis of the lanthanides and to eliminate isobaric interferences in the separation of the actinides. Separation of fission... 

Examples of the Compositions of Scrubbing and Stripping in Processes for Actinides Separation... 

Ozawa, M., Hirano, H., Koma, Y., Kawata, T. 1995. Enhancing actinides separation by consolidated PUREX and TRUEX processes intensified by salt-free requisite. Int. Conf. Evaluation of Emerging Nuclear Fuel Cycle Systems. GLOBAL 95, Vol. 1, Versailles, France, September 11-14, pp. 585-594. 

Del-Cul, G.D., Bond, W.D., Toth, L.M. et al. 1994. Citrate based TALSPEAK lanthanide-actinide separation process. ORNL/TM-12785. 

Miguirditchian, M., Chareyre, L., Heres, X. et al. 2007. GANEX Adaptation of the DIAMEX-SANEX process for the group actinide separation. GLOBAL 2007, Boise, ID, September 9-13. 

Morita, Y., Sasaki, Y., Tachimori, S. 2001. Development of TODGA extraction process for high-level liquid waste Preliminary evaluation of actinide separation by calculation. Proc GLOBAL 2001, Paris, France, September 9-13. 

Mason, G.W. Griffin, H.E. Demonstration of the potential for designing extractants with preselected extraction properties possible application to reactor fuel reprocessing, In Actinide Separations, J.D. Navratil and W.W. Schulz (Eds.), American Chemical Society, Washington, DC (1980), pp. 89-99. 

It should be noted, however, that a simplified version of the DIAMEX-SANEX/ HDEHP process was also successfully implemented on a genuine highly active DIAMEX product (An(III) + Ln(III) fraction) in 2005, as the second step of an An(III)/Ln(III) partitioning scheme, in the scope of the technical feasibility validation of minor-actinide separation proposed by the CEA to address the issues of the 1991 French radioactive waste management act (154). 

Choppin, G., Nash, K. 1995. Actinide separation science. Radiochimica Acta 70/71 225-236. 

Facchini, A., Amato, L., Nannicini, R. 1996. A two-cycle process for enhanced actinide separation from radioactive liquid wastes. Separation Science and Technology 31(16) 2245-2256. 

Musikas, C. 1988. Potentiality of nonorganophosphorus extractant in chemical separations of actinides. Separation Science and Technology 23(12 13) 1211-1226. 

Geist, A., Weigl, M., Gompper, K. 2004. Hydrometallurgical minor actinide separation in Hollow Fibre Modules. ATALANTE 2004 Advances for Future Nuclear Cycles, June, Nimes, France. 

Sasaki, Y., Sugo, Y., Tachimori, S. 2000. Actinide separation with a novel tridentate ligand, diglycolic amide for application to partitioning process. ATALANTE 2000 Scientific Research on the Back-end of the Fuel Cycle for the 21st Century, October, Avignon, France. 

Magnusson, D., Christiansen, B., Glatz, J.P., Malmbeck, R., Modolo, G., Serrano Purroy, D., Sorel, C. 2008. Demonstration of minor actinide separation from a genuine PUREX raffinate by TODGA/TBP and SANEX reprocessing. ATALANTE 2008 Nuclear Fuel Cycles for a Sustainable Future, May, Montpellier, France. 

In order to find compounds able to perform an efficient lanthanide/actinide separation, the Twente group prepared two cavitands (Cvl and Cv2) functionalized with CMPO groups and two cavitands (Cv3 and Cv4) with carbamoylmethylphosphonate (CMP) groups192193 (see Section 4.7). Distribution ratios displayed by CMPO cavitands are much lower than those found for the calixarene counterpart. This important decrease of extracting ability of cavitand is probably due to the presence of a carbon atom between the benzene unit and the nitrogen atom, causing N-protonation below pH 2. Furthermore, the Am/Eu selectivity is less than that of CMPO-calix[4]... 

However, the conditions are often far from those of industrial situations. In order to better simulate solvent degradation during the PUREX process, a test loop was created in the 1990s in a CEA laboratory (Fontenay-aux-Roses, France), with the EDIT loop (Extraction Desextraction Irradiation Traitement) (21, 22). The laboratory simulation of industrial conditions consisted of a succession of representative physical and chemical treatments after the irradiation of the solvent (i.e., alkali and acid treatments, distillation). Indeed, these treatments can modify the final solvent composition because of the elimination of some compounds or the occurrence of secondary reactions. A few years later, the MARCEL (Module Avance de Radiolyse dans les Cycles d Extraction Lavage) test loop was built at Marcoule to follow the regeneration efficiencies of degraded solvents involved in actinide separation processes (4, 5). 

Actinide Separations in Flow Systems using CMPO Chemistry on TRU-Resin... 

Actinide separation method development in automated FI format On-line liquid scintillation 81... 

Actinide separations conditions investigated using column separation automated in ion chromatographic instrument ICP-MS 61... 

Briefly compares UTEVA-Resin unfavorably with TRU-Resin for actinide separations for ICP-MS ICP-MS 60... 

FIGURE 9.11 Capacity factors, k, against nitric acid concentration for three resins used in actinide separations. (Data for these plots were originally published in Refs. 30, 31, 127, and data traces were adapted from www.eichrom.com where they are shown in color. With permission.) (From Horwitz, E. P., Dietz, M. L., Chiarizia, R., Diamond, H., Maxwell, S. L., and Nelson, M. R., Anal. Chim. Acta, 310, 63-78, 1995. With permission.)... 

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