MATHEMATICAL MODELLING OF THE SYSTEM OF UO_2(NO_3)_2-HNO_3 -H_2O/30% (VOL.) TBP-KEROSENE IN SOLVENT EXTRACTION PROCESS——Ⅲ. A MODEL FOR CALCULATING THE DISTRIBUTION COEFFICIENTS OF URANYL, PLUTONIUM NITRATES AND NITRIC ACID

Using data published in the literature and based on the mathematical model for estimating distribution coefficients of uranium and nitric acid in system UO2 (NO3)2-HNO3 -H2O/30% TBP-kerosene, a relation for the estimation of distribution coefficients of plu-tonium in microconcentration is obtained.In the case of plutonium in macroconcentration, the effect of plutonium quantity on its distribution and on uranium distribution must be considered. Therefore the factor Ru found in system of UO2 (NO3)2-HNO3 is revised and the mathematical model for estimating distribution coefficients for plutonium, uranium nitrates and nitric acid in system of UO2 (NO3)2-Pu (NO3)4-HNO3-H2O/30% TBP-kerosene established.Using this model, the average deviation of calculated values compared with those obtained experimentally is 11.0% for micro-quantity of Pu and 9.6%, 9.4% and 15.9% for macroquantity of plutonium, uranium and nitric acid respectively.This mathematical model may be applied for the calculation and selection of technological parameter in solvent extraction process.