Sorption of radionuclides on sandstones and mudstones

As an extension to earlier work, the sorption of a range of radionuclides on Darley Dale sandstone and London clay is being investigated. Techniques employed are batch, through-diffusion, in-diffusion and high-pressure convection. The last named has been found to show much potential for studying both hard and soft rock types with low or medium sorbing nuclides. At the 80 bar pressure used, breakthrough times are shortened by nearly 10000 times, in the case of sandstone for example. Any non-equilibrium effects with this technique lead to an under-estimate of the sorptivity. In-diffusion studies have shown that this method also has some potential but further refinement in the area of sample sectioning is required. Through-diffusion and batch continue to be extremely useful techniques within their respective limitations of timescale and unrealistic surface area. (orig.)