MOISTURE MOVEMENT UNDER A TEMPERATURE-GRADIENT IN HIGHLY COMPACTED BENTONITE

The heat induced moisture movement in buffer materials to be used for the geologic disposal of high-level radioactive waste is investigated by a series of experiments and numerical simulations. Highly compacted blocks of Japanese Na bentonite are used in the experiments as the bu ffer materials. Mechanistic models including those proposed by Philip et al. and Ewen et al. are formulated to the finite-element program wh ich are applied to interpret the experimental results. The applicabili ty of the mechanistic models to the compacted bentonite is examined. T he numerical results agree well with the experimental results qualitat ively, though a few quantitative discrepancies are found. Those discre pancies demand better descriptions for material properties on compacte d bentonite and introducing an effect of volume change associated with change in water content.