MODELS OF URANIUM DISSOLUTION IN NATURAL WATERS OF VARIOUS COMPOSITIONS

Abstract

Computer simulations were used to clarify some principal problems of the interaction of natural waters of various types with natural and anthropogenic U-bearing phases U(cr), UO2(cr), U 4O9(cr), U3O8(cr), UO 2(OH)2(cr), and UO3(cr), in a thermodynamically closed system. The problems discussed include the solubilities of these phases, modes of U occurrence in waters in equilibrium with each of the solid phases, transformations of the solid U-bearing phases in contact with waters, and the alterations in the waters themselves in contact with the U-bearing phases. The effect of external factors that are able to change the physicochemical conditions in the contact of U with waters on these processes is elucidated. The factors encompass differences in the R/W ratios, drastic changes in pH and Eh due to the simultaneous dissolution of U and other anthropogenic products, and the heating of the reaction zone.