Sorption of Ba and Ra on montmorillonite in the presence of Ca

Ishidera, Takamitsu ; Shibutani, Sanae*; Hamamoto, Takafumi*

In the geological disposal of high-level radioactive waste, Ra-226 is one of the relevant radionuclides for the safety assessment. In this study, the sorption behavior of Ba and Ra on Na-type and Ca-type montmorillonite was investigated by batch sorption experiments to confirm the applicability of Ba sorption data as an analogue for Ra. The results of sorption experiments indicated that the there was no significant difference in the selectivity coefficients and surface complexation constants of Ba and Ra. This implies that the sorption data of Ba can be applied to estimate the sorption of Ra both on Na-type and Ca-type bentonite.