Fe distribution, redox state and electrochemical activity in Boom Clay

In the context of radioactive waste disposal in clay formations, the sorption of a number of redox sensitive radionuclides (e.g. U, Se, Tc) is controlled by the presence of Fe-containing minerals, mainly smectite (Guimaraes et al., 2016), illite (Bruggeman and Maes, 2010), and pyrite (Breynaert et al., 2010). In the repository lifetime, oxidizing conditions will prevail during the open drift phase enhanced by ventilation followed by recovery of reducing conditions after back-filling. Thus Fe-containing minerals will be subjected to redox cycles in the course of the repository operation. In order to evaluate the sensitivity of different Fe containing minerals in the Boom Clay to changing redox conditions, Fe2+/Fe3+ partitioning was determined in various size fractions (