Alexander Osipenko

Joint solubility of PuF3 and CeF3 in ternary melts of lithium, thorium, and uranium fluorides

Joint solubility of PuF3 and CeF3 in melts of the molar composition 78LiF-7ThF4-15UF4 and 72.5LiF-7ThF4-20.5UF4 in the temperature range 550°-800°C was studied. Anhydrous PuF3 and CeF3 spiked with 144Ce, and also anhydrous ThF4 were synthesized. Isothermal saturation method was used for studying the solubility of pressed PuF3 and CeF3 pellets in these melts in an inert (argon) atmosphere. The dependence of the joint solubility of PuF3 and CeF3 on the melt temperature was determined.

Electrochemistry of Curium in Molten Chlorides

Molten salts and especially fused chlorides are the convenient medium for selective dissolution and deposition of metals. The existence of a wide spectrum of individual salt melts and their mixtures with different cation and anion composition gives the real possibility of use the solvents with the optimum electrochemical and physical-chemical properties, which are necessary for solving specific radiochemistry objects. Also molten alkali metal chlorides have a high radiation resistance and are not the moderator of neutrons as aqua and organic mediums [Uozumi, 2004; Willit, 2005].

Preparation of the intermetallic compound PuPd3 and its electrochemical properties in the 3LiCl–2KCl salt eutectic

The intermetallic compound (IMC) PuPd3 was synthesized by induction fusion of the components in a vacuum. The phase composition of the compound was confirmed by X-ray diffraction analysis. SEM analysis revealed the presence in the sample obtained of three metastable PuPdx phases (2.3 < x < 4.4) differing in the extent of enrichment in Pu. Data on the electrochemical properties of PuPd3 in the 3LiCl–2KCl salt eutectic were obtained for the first time. Three main peaks of anodic oxidation are observed in the cyclic voltammogram of PuPd3 at potentials of–1.74,–1.24, and–0.09 V (vs. Ag/AgCl). At potentials exceeding +0.6 V (vs. Ag/AgCl), PuPd3 passes into the transpassive state. At lower potentials, anodic oxidation of IMC leads to the Pu dissolution in the form of Pu(III), but the simultaneously oxidized Pd is reduced on the electrode, which results in the enrichment of its surface in Pd.

Thermodynamics of Nuclear Waste Reprocessing: Separation of Lanthanides Using Liquid Metals and Alloys

Thermodynamics of separation of praseodymium and neodymium employing liquid low-melting metals and alloys is considered. Pr/Nd separation factors on liquid Ga, In, Bi, and Ga-In eutectic were calculated from the thermodynamic data. The obtained results are compared with the literature data on experimentally determined separation factors on “traditional” liquid metals: Bi, Zn, and Cd. It is shown that one-stage selective extraction of praseodymium or neodymium from the mixture using any of the mentioned metals is not possible. In the separation process of lanthanides from minor actinides using a chloride molten salt–liquid metal system, cerium group lanthanide fission products will be accumulated in the salt phase.

Electrochemistry of Tm(III) and Yb(III) in Molten Salts

Pyrochemical processes appeared today gives an interesting option for future nuclear fuel cycles in several aspects. These latter will have to provide high recovery yields for actinides elements, (taking into account the sustainability requirement) to be safe, resistant versus proliferation risks, and cost-effective. This lead to a rather prolific research today, with many innovative concepts for future reactors, future fuels, and obviously future processes. Pyrochemical processes seems in this context to offer significant-established or presumed-advantages: (i) low radiolytical effects versus solvent processes (which increases the ability to process high burn-up, short-time cooled hot fuels); (ii) ability to dissolve new ceramic or dense fuel compounds; (iii) presumed compactness of technology (low number of transformation steps, small size of unit operations) [Uozumi, 2004; Willit, 2005]. Partitioning and transmutation (PT Castrillejo et al., 2005a, 2005b, 2005c, 2009; De Cordoba et al., 2004, 2008; Kuznetsov et al., 2006; Novoselova &