Sorption and migration of Cs, Sr, and Eu in gypsum - groundwater system

The distribution of 137Cs, 152Eu, and 85Sr in a solid/aqueous system, gypsum in contact with groundwater, was investigated using gamma-spectrometry. The sorption and migration of the radionuclides were investigated. The aqueous phase was characterized using instrumental neutron activation analysis (INAA) and high performance liquid chromatography (HPLC). The solid phases were characterized using X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The investigations included three kinds of gypsum: mineral, commercial, and own prepared gypsum. The influence of some parameters on sorption/migration of the radionuclides were studied, such as contact time, pH, and concentrations of concurrent elements. The effect of element concentration was also investigated. The results show the ability of gypsum to keep Sr and Eu in the solid phase in all three cases. The incorporation of Cs in the solid phase depends on the conditions and used materials, and varies between 93 and 97%.