Investigation of dry unit weight for Bentonite buffer block

In terms of dry unit weight, its value should be higher at least 1600 kg/m³ in order to satisfy the performance criteria, and it is necessary to investigate dry density of buffer material exactly. Therefore, this paper analyzed the method for investigating dry unit weight of cylindrical bentonite buffer block. This paper investigated methods to obtain dry unit weight for bentonite buffer material which is a very important component in the EBS system for the geological disposal of HLW. Measured value showed 3⁓5% higher than calculated one. Since bentonite buffer block is confined with rock mass and backfill materials in the real disposal condition, volume change may not occur according to temperature and water content variation. Therefore, it might be more accurate to use calculated value in order to obtain dry unit weight of benotonite buffer material, not measured value after drying in the oven