An Evaluation of solubility limits on maximum uranium concentrations in groundwater

Iwatsuki, Teruki  ; Arthur, R. C,*

Maximum uranium concentrations in groundwaters associated with a uranium ore deposit in Japan appear to be controlled by the solubility of the amorphous hydrous oxide, UO(am). This conclusion is supported by calculated saturation indices for this mineral using geochemical data characterizing the deposit and its surroundings. The conclusion that UO(am) appears to be solubility controlling in a natural system that has evolved over long periods of time supports the assumption adopted in many international studies that the solubility of this phase would limit the aqueous concentrations of U released from a deep geologic repository for nuclear wastes over similar time scales. Natural systems can thus provide a useful framework for testing assumptions and models used in repository safety assessments.