Radioiodine 129I is included in TRU waste, and causes human thyroid gland. The sorption/ desorption behavior of IO3－ into/from ettringite (AFt), which is one of the representative cement hydrates, was investigated. In the sorption experiment, AFt was immersed in KIO3 solution. The time dependence of sorption amounts and the changes of lattice constants were analyzed. In the desorption experiment, the sample sorbed by IO3－, was extracted by different desorption solutions, and the concentrations of desorbed IO3－ and the changes of lattice constants were measured.
cement, ettringite, IO3－, sorption, desorption.