Mathematical modelling of extraction equilibria of actinoids and extraction technology

A brief review of works conducted by Soviet authors on the description of extractional equilibria of actinides (determination of activity coefficients by the extraction data included) and on mathematical simulation of extraction processes, technetium effect on uranium - plutonium separation in particular, is presented. A model of technetium (7) distribution is plotted, formation of HTcO4(H2O)·TBP complexes is taken into account. Algorithm for solution isopiesticity detection is suggested. Diddiculties in the simulation of the calculation of uranium - plutonium separation devices for reprocessing of the WWER fuel elements with a high burnup which contain large amounts of technetium (up to tens mg/l), are considered. It is shown that at present it is possible to simulate practically all the stages of extraction reprocessing of spent fuel quite reliably