Characterization of radium-226 in uranium mill tailings

The choice of an input source term to define radium concentration for numerical transport models and quantification of the total mass of radium available for transport has been a challenge when attempting to predict long term impacts of uranium mill tailings storage. A study of fresh uranium mill tailings from Cluff Lake was undertaken to examine the distribution of radium within the tailings mass. Techniques used to characterize the tailings included solid and liquid chemical analyses, batch tests, scanning electron microprobe examination, physical separation using sieve analysis and chemical separation using sequential leaching. The study concluded that less than 0.5 % of the total radium mass was mobilized by deionized water leaching. Evidence was obtained which indicated that equilibrium pore fluid concentrations for radium may be estimated from the solid and liquid chemistry. Calculated radium predictions reasonably represent the empirical data obtained from Cluff Lake uranium mill tailings pore fluids.