Influence of bentonite colloids on the migration of the radionuclide Se(IV) in granite fracture under reducing conditions

Bentonite colloids and fluid velocity significantly influence the migration behavior of the redox sensitive nuclide Se(IV) in the disposal repository. In this study, the migration behavior of Se(IV) in artificial fracture, which was created by Beishan granite and polyethylene pipe, was studied under reduced condition, with Br − as a tracer. The effects of bentonite colloids and fluid flow rate on the migration of Se(IV) in the fracture were explored. The results show that a part of Se(IV) would adsorb on the surface of granite in reduced condition. The maximum penetration rate of Se(IV) increases with the decrease of water flow rate. In addition, the colloids hindered the migration of nuclide Se(IV) in the fissure to some extent during the process of co-migration.