Curium in molten chlorides
Study of Curium Thermodynamics in Molten Chlorides
Tech Area / Field
- ENV-RWT/Radioactive Waste Treatment/Environment
8 Project completed
Senior Project Manager
Tocheny L V
NIIAR (Atomic Reactors), Russia, Ulianovsk reg., Dimitrovgrad
- Royal Institute of Technology / Division of Reactor Physics, Sweden, Stockholm\nCEA, France, Paris\nEuropean Commission / Joint Research Center / Institute for Transuranium Elements, Germany, Karlsruhe\nCiemat, Spain, Madrid
Project summaryCurium isotopes contained in spent nuclear fuel have a high specific heat rate and long half-life, and they should be recovered from high-level wastes (HLW) and transmutated. The objective of the proposed investigation is to obtain the data on thermodynamics of curium compounds formation in molten chlorides. These fundamental data can be subsequently used for feasibility assessment of the processes of curium recovery in molten chlorides.
Molten chlorides have a high radiation resistance compared with that of aqueous and organic media. This fact is of significant importance because curium has a high specific activity. The data on curium behavior in the molten chlorides are not comprehensive enough, and they refer to curium conventional standard potential in the alloy with zinc  and distribution coefficient between salt and liquid metal phases . There is no data on thermodynamics of formation of oxygen and oxygen-free curium compounds in a wide range of molten chlorides, including those proposed at present for spent fuel reprocessing and partitioning of wastes. The obtaining of these data will contribute to providing a fundamental basis for development of the curium recovery processes in molten media.
During a long period of time the RIAR has been studying the properties of oxygen and oxygen-free compounds of minor actinides (Am, Np) in the molten chlorides [3, 4, and 5] for the purpose of transmutation using the methods of potentiometric titration, cyclic voltammetry, and chronopotentiometry. The application of the method of potentiometric titration, using an oxygen pump made of zirconium-yttrium or zirconium-scandium ceramics, makes it possible to reduce by a factor of tens the amount of the studied element, which is involved in the experiment. This fact is of great importance because of a high curium cost.
The curium studies at the RIAR [1, 6-10] have been mainly related to production of radioisotope products.
The proposed project will contribute to integration of Russian weapon scientists into the international scientific community.
The results of the proposed project are expected to contribute to obtaining the fundamental data on curium behavior, which can be used for feasibility assessment of the curium recovery processes in the molten chlorides.
The following studies are planned to be performed by RIAR:
- Task 1: Thermodynamics of formation of oxygen curium compounds.
The RIAR will carry out the experiments using the potentiometric titration method in several solvents (LiCl-KCl, NaCl-CsCl, NaCl-KCl) at several temperatures (in the range from 450 to 850оС). The data on instability constant for soluble compounds, products of solubility for insoluble curium compounds, Gibbs energy change during formation of these compounds will be obtained. The dependences of the above parameters on the inverse effective radius of a solvent cation will be determined. It will be useful for calculation of similar thermodynamic data for other solvents.
- Task 2: Thermodynamics of formation of oxygen-free curium compounds.
The RIAR will carry out the experiments using the methods of cyclic voltammetry, chronopotentiometry in several solvents (LiCl-KCl, NaCl-CsCl, NaCl-KCl) at several temperatures (in the range from 450 to 850оС). The data on conventional standard potentials of curium depending on the inverse effective radius of a solvent cation, Gibbs energy change during formation of these compounds will be obtained. It will be useful for calculation of similar thermodynamic data for other solvents.
- Task 3: Simulation of curium behavior in molten chlorides.
On the basis of the data obtained under Tasks 1 and 2 Pyurbe diagrams will be plotted for the studied solvents, and a three-dimensional model of curium behavior in the molten chlorides will be obtained.
- V.P.Kolesnikov, V.N. Kazantsev, O.V.Skiba Electrochemical behavior of americium and curium in molten alkali metal chlorides. Radiochemistry, 1977, 19, No.4, pp. 545–548
- T.Koyama., et al.:J.Alloys Compounds, 189,37 (1992)
- A.G. Ossipenko, et al.: Study of Americium Behavior in molten chlorides in presence of oxygen// J. of NUCLEAR SCIENCE and TECHNOLOGY, Supplement 3(November 2002), p.p.592-594
- M.V.Kormilitsyn, A.V. Bychkov Features of electrochemical behavior of neptunium in the pyroelectrochemical processes of MOX-fuel production form molten chlorides “First All-Russian Radiochemistry Conference, Dubna, 17-19.05,1994” Abstracts, Moscow, 1994, p. 176
- A.V. Byckkov, O.V. Skiba, A.A. Maershin, V.A. Kisly, S.K. Vavilov, M.V. Kormilitsyn, L.S. Demidova, L.G. Babikov, R.A. Kuznetsov Fuel cycle of actinide burner-reactor. Review of investigation by “DOVITA” program, Global 97, p. 657
- V.M. Radchenko, M.A. Ryabinin, N.N. Andreytchuk, V.D. Gavrilov, Ye.A. Karelin Curium-248 standard neutron source, Appl. Radiat. Isot. Vol. 53, No.4-5, pp. 833-835, 2000
- V.M. Radchenko, A.G. Seleznyov, M.A. Ryabinin, R.R. Droznik, Synthesis and study of binary compounds of actinides and lanthanides. Irradiation effects on the structure of intermetallides of curium-244. Radiochemistry, 1999, Vol. 41 No.1, pp.44-48
- V.M. Radchenko, A.G. Seleznyov, R.R. Droznik, M.A. Ryabinin Synthesis and study of binary compounds of actinides and lanthanides. Curium intermetallides with silicon. Radiochemistry, 1998, Vol.40, No.1, pp. 6-8
- V.M. Radchenko, A.G. Seleznyov, M.A. Ryabinin, R.R. Droznik., V.Ya. Vasilyev Synthesis and study of binary compounds of actinides and lanthanides. Curium intermetallides with nickel. Radiochemistry, 1995, Vol. 37, No.4, pp. 317-321
- V.M. Radchenko, A.G. Seleznyov, M.A. Ryabinin, R.R. Droznik., V.Ya. Vasilyev Synthesis and study of binary compounds of actinides and lanthanides. Study of 244Cm alloy with platinum, iridium and rhodium obtained by metal curium vapor condensation. Radiochemistry, 1994, Vol.36, No. 4, pp. 229-303
The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.
ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.