LIANG Dong, LIU Wei, YANG Zhong-tian*, LI Hong-hui, LIU Yu-chen

(China Institute for Radiation Protection, CNNC Key Laboratory on Geological Disposal of High-Level Radioactive Waste, Taiyuan 030006, China)

Abstract: In order to understand the impact of gamma irradiation on the mineral components and microstructures of the Gaomiaozi (GMZ) natural sodium-based bentonite and to expand the assessment scope of properties of buffer materials for the geological disposal of high-level radioactive wastes (HLW), the GMZ natural sodium-based bentonite in Inner Mongolia and groundwater from the Beishan area have been selected as research objects for studying the variation of functional groups, mineral components, and occurrences and contents of iron of the GMZ natural sodium-based bentonites which were gamma irradiated with accumulative irradiation dosages of 500 kGy, 1000 kGy, 1500 kGy, 2000 kGy, 2500 kGy, and 3000 kGy, respectively by using methods of the FTIR, XRD, and M？ssbauer spectrometry in this paper. In addition, the Si solubility of the bentonite into groundwater in the Beishan area has also been studied. The results indicate that Fe(Ⅱ) contents of bentonites are obviously increased but Fe(Ⅲ) contents of bentonites are decreased significantly with the increase of the accumulative irradiation dosages. The concentrations of SiO32- in groundwater are increased obviously with the increase of irradiation dosages. The gamma irradiation may cause a certain variation of numbers of functional groups in the irradiated bentonite. The percentages of montmorillonite are increased, but those of quartz and albite are decreased, with no variation in numbers of minerals and functional groups in the bentonite. In general, some properties of the GMZ natural sodium-based bentonite are obviously varied after the γ-ray irradiation on the bentonite. The detailed variation of those properties needs to be furtherly studied.

Keywords: The γ-ray irradiation; the natural sodium-based bentonite; mineral component; high-level radioactive waste；geological disposal

ACTA MINERALOGICA SINICA Vol. 40, No.3, 2020, page 281-288