The Influence of γ-Rays Irradiation and Thermal Sequence Aging on the Mineral Composition of GMZ Sodium Bentonite

Abstract

This paper aims to determine the impacts of γirradiation and thermal sequence aging on the mineral composition of Gaomiaozi natural sodium bentonite with Beishan groundwater and to broaden the assessment and scope of buffer materials for geological disposal of high-level radioactive waste (HLW). FTIR, XRD and Mössbauer spectra of the bentonite (contain groundwater from Beishan area) have been studied that under accumulative radiation with doses at 3.0 MGy, hereafter heated at 90 °C, 150 °C, 170 °C, 190 °C and 210 °C respectively continue 2 monthes, 4 monthes, 6 monthes, 8 monthes, 10 monthes and 12 monthes. In addition, the solubility of silicon in groundwater from Beishan area have been tested. The results indicate that, the content of montmorillonite decreased significantly with the increment of the thermal temperature and time. The concentration of SiO3 2- in groundwater increased obviously as the thermal temperature and time increased. There have the tendency that Fe (IItransformed to Fe(III) in the bentonite after aged, however, the content of Fe(II) increased and the content of Fe(III) decreased aged by γ irradiation. But the types of mineral and functional groups remain the same. All in all, the mineral composition of GMZ natural sodium bentonite have been varied after thermal aged, and further research is needed to comprehend specific sitiations.