Measurement of thermal diffusivity of compacted bentonite filled with silica sand as a buffer material of HLRW in underground disposal

Bulk effective thermal diffusivity, aBS, of compacted bentonite specimens mixed with silica sand to improve heat conducting properties of pure compacted bentonite has been measured by a constant rate heating (or cooling) method under various conditions at temperature ranges from 20 to 80degC. Bentonite used is Na-bentonite produced in Yamagata prefecture, Japan (commercial name:KUNIGEL-V1). Physical properties of the specimens were varied between 1490 and 2010 kg/m3 of dry density, ρD, 25 and 45% of porosity, Φ, 42 and 95% of degree of water saturation, S, at a constant filling rate, f, of 30% of silica sand. A correlation formula for the aBS based on a three phase model to clarify the effect of f, ρD, Φ and S on the aBS of the compacted bentonite filled with silica sand. (author)