Actinides dissolution

For complexation experiments, a known mass of dendrimer was dissolved in the aqueous phase containing actinides (dissolution was accelerated by ultrasonication), and the solution was filtered. The filtrate was recovered and contacted with a new known mass of dendrimer and filtered again. These operations were repeated three or four times. 

In 1995, Nevissi and Strebin described a simple fluidic system to deliver sample and reagents to a TRU-Resin column for the separation of Pu and Am.79 A filter was included on-line to capture a precipitate containing the actinides dissolution of the precipitate transferred the sample onto the column downstream. Radionuclides were detected with a-spectrometry off-line. 

While actinide metals are easily soluble in some mineral acids such as HCl an.d HCIO4, they are typically found in solution in valences IV to VI. However, Baluka and co-workers first reported in 1981 that dissolution of U and Np metals in superacids produces initially trivalent actinides (Baluka et al. 1981). The UV-visible spectra of the U and Np solutions, shown in fig. 2, are characteristic of the trivalent actinides found in aqueous acidic or basic systems. Avens and colleagues (1988) have dissolved both Pu and Am metal and observed trivalent species by UV-visible spectroscopy. The stability of oxidation state (111) for U, Np and Pu is all the more striking especially in light of the lower stability of the series U (lll)-Pu (111) relative to higher oxidation states e.g., trivalent uranium (111) is able to reduce water under normal conditions. In addition to the unusually low oxidation state obtained, another feature of actinide dissolution in... 

Heimann, R.B. and Vandergraaf T.T. (1988) Cubic zirconia as a candidate waste form for actinides dissolution studies. J. Mater. Sci. Lett., 7, 583-586. 

Synthesis in liquidAl Al as a reactive solvent Several intermetallic alu-minides have been prepared from liquid aluminium very often the separation of the compounds may be achieved through the dissolution of Al which dissolves readily in several non-oxidizing acids (for instance HC1). For a review on the reactions carried out in liquid aluminium and on several compounds prepared, see Kanatzidis et al. (2005) binary compounds are listed (Re-Al, Co-Al, Ir-Al) as well as ternary phases (lanthanide and actinide-transition metal aluminides). Examples of quaternary compounds (alumino-silicides, alumino-germanides of lanthanides and transition metals) have also been described. As an example, a few preparative details of specific compounds are reported in the following. 

Since the water movement will be very slow compared with the rate at which the wastes dissolve, we are concerned first and foremost with equilibrium solubility. Also, if only to relate behaviour on the geological time scale to that on the laboratory time scale, we will need to know about the mechanisms and kinetics of dissolution and leaching. The waste forms envisaged at present are glass blocks containing separated fission products and residual actinides fused into the glass and, alternatively, the uranium dioxide matrix of the used fuel containing unseparated fission products and plutonium. In the... 

The different methods of actinide refining are based in part on experience in refining rare earth metals In these methods, actinide metals and their impurities undergo selective phase transitions like evaporation and condensation, melting and dissolution which result in a separation of the constituents of the sample to be purified. 

Trofimov, T.I. Samsonov, M.D. Kulyako, Y.M. Myasoedov, B.F. Dissolution and extraction of actinide oxides in supercritical carbon dioxide containing the complex of tri-n-butylphosphate with nitric acid, C.R. Chimie 7 (2004) 1209-1213. 

This review will exclusively deal with studies related to solvent-extraction processes (neither solid-phase precipitation nor ion-exchange chromatography) aiming at separating trivalent actinides from PUREX raffinates or spent-fuel dissolution... 

Spencer, B., Egan, B.Z., Beahm, E.C., Chase, C.W., Dillow, T.A. 1999. Dissolution of ORNL HLW sludge and partitioning of the actinides using the TRUEX process. Separation Science and Technology 34(6 7) 1021-1042. 

Distribution ratios and transport were carried out on real HAW arising from dissolution of a mixed oxide of uranium and plutonium (MOX) fuel (burnup 34,650 MW d/tU), where uranium and plutonium have been previously extracted by TBP.86 The experiments were performed in the CARMEN hot cell of CEA Fontenay aux Roses with two dialkoxy-calix[4]arene-crown-6 derivatives (diisopropoxy and dini-trophenyl-octyloxy). High cesium distribution ratios were obtained (higher than 50) by contacting the HAW solution with diisopropoxy calix[4]arene-crown-6 (0.1 M in NPHE). Moreover, the high selectivity observed with the simulated waste was confirmed for most of the elements and radionuclides (actinides or fission products Eu, Sb, Ce, Mo, Zr, and Nd). The residual concentration or activity of elements, other than cesium, was less than 1% in the stripping solution, except for iron (2%) and ruthenium (8%) the extraction of these two cations, probably under a complexed... 

Samsonov, M. D. Trofimov, T. I. Vinokurov, S. E. Lee, S. C. Myasoedov, B. F. Wai, C. M. Dissolution of actinide oxides in supercritical carbon dioxide modified with various organic ligands. In Proceedings of the International Solvent Extraction Conference 2002, ISEC 2002, eds. K. C. Sole, P. M. Cole, J. S. Preston, and D. J. Robinson, SAIMM, Johannesburg, South Africa, 2002, pp. 1187-1192. 

---