Seversk Technological Institute of National Research Nuclear University “MEPhI

A. S. Buynovskiy, Professor, Department of Chemistry and Technology of Contemporary Energetics’ Materials, Technological Faculty, e-mail: bas@ssti.ru

E. P. Marinenko, Senior Research, Department of Chemistry and Technology of Contemporary Energetics’ Materials, Technological Faculty

V. L. Sofronov, Professor, Dean of Technological Faculty

This article contains the results of the research on refining plutonium trichloride by vacuum distillation of impurities from the melt at temperatures above the melting point of plutonium trichloride (760 ^oC) and from the layer of powdered product at temperatures below the melting point of plutonium trichloride (PTC). The results of theoretical analysis of the process of removing impurities from molten PTC showed the possibility of efficient removal of impurities such as chlorides of magnesium, nickel, manganese, chromium, uranium, silicon, aluminum, lead, iron, and molybdenum at temperatures above the melting temperature of PTC. It is shown that to improve the process of refining it is necessary to organize an intensive mixing of the melt. The effectiveness of treatment of powdered PTC by molecular distillation of the impurities, depends on particle size of PTC and on diffusion coefficient of impurities. Diffusion coefficient is determined by the temperature of the process. Consequently, the efficiency of the process will be determined not only by the above-mentioned factors, but also by the speed of removal of impurities from the surface of the particles. Therefore it is recommended to hold the cleaning process of PTC's powder with a continuous purge by argon, chlorine, or any other gas. The paper contains descriptions of plants to clean up plutonium's trichloride from impurities by vacuum distillation (the typical plant consists of vacuum furnace ShP-1, systems of pumping argon and evacuation of gases); methods of conducting research and analysis; the results of the experiments of the process of PTC purification by molecular distillation of impurities of Ni, Fe, Al, Mn, Cr, Pb, Ca, Cr, Mg chlorides from the layer of powder or molten plutonium trichloride; experimentally determined relaxation time and coefficients of diffusion of chloride impurities in the melt plutonium trichloride.

The authors thank V. P. Korobtsev, V. A. Khokhlov, P. Shtephan, M. Chigryaev for their creative contributions in the present research.

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