fracture-filling clays in Beishan granite, Gansu: Application to selecting the site of high-level radwaste repository in China

The first results of sorption experiments of U(VI), 234 U(VI) and 238 U(VI) onto original (unpurified) fracture-filling clays from No.1 monzonitic granite intrusion, Beishan area, Gansu Province, China are reported. The monzonitic granite intrusion is a potential location for a high-level radwaste (HLW) repository in China. The present experimental results show that the maximum U(VI) sorption reached 92% at near-neutral pH and the distribution coefficient (Kd) was 1226 mL/g. A high sorption capacity of the fracture-filling clays in host rock on radioactive ele- ments is necessary for HLW deep geological disposal repository. No preferential sorption of 234 U onto the clays was found. Finally, the sorption of U(VI) onto the clays was also modeled using a surface complexation model.