Application of Aluminium Nitrate for Extraction Reprocessing of Spent Nuclear Fuel
V. A. KARELIN, I. V. PETLIN, N. A. ZHURAVLEV, N. V. KARELINA, I. V. RASPUTIN
National Research Tomsk Polytechnic University, Tomsk, Russia
Keywords: aluminium nitrate as a salting-out agent, uranyl nitrate UO(NO), plutonyl nitrate PuO(NO), tributyl phosphate, distribution coefficients of uranium and Pu, tetravalent uranium (U)
Pages: 311-316
Abstract
The effect of the salting-out agent, aluminium nitrate (Al(NO3)3), on the extraction properties of hexavalent uranyl and plutonyl nitrates (UO2(NO3)2 and PuO2(NO3)2) is studied. It is shown that in 4-8 М HNO3 solutions (aqueous phase) with an increase in Al(NO3)3 concentration from 0.1 to 1 M, uranium distribution coefficient increases sharply during extraction in 30 % solution of tributyl phosphate (TBP) in a hydrocarbon solvent (organic phase). In the presence of aluminium nitrate, the distribution coefficient of Pu6+ increases most significantly in comparison with other valence forms of Pu. The efficiency of salting-out action increases with an increase in TBP concentration in the organic phase: in the presence of 0.1-2.0 М Al(NO3)3, the distribution coefficient of Pu6+ in a 30 % solution of TBP increases three times faster than in its 4.5 % solution. The efficiency of reductive stripping of hexavalent plutonium (Pu6+) by tetravalent uranium (U4+) increases in the presence of aluminium nitrate. In the presence of 1 M Al(NO3)3, the coefficient of PuO22+ distribution does not exceed 1.0 even at low concentrations of U(NO3)4 (50 g/L) and HNO3 (0.5 M). The concentration of HNO3 in the aqueous phase strongly affects the change in Pu6+ distribution coefficient. However, with an increase in the concentration of U(NO3)4 in the stripping solution, the rate of a decrease in the coefficient of Pu6+ distribution drops down. With an increase in U(NO3)4 concentration from 50 to 150 g/L, this parameter decreases by a factor of 2.6, and in more concentrated U(NO3)4 solutions (150-250 g/L) it decreases by a factor of 1.1.
DOI: 10.15372/CSD2021308
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