Evaluation of geomechanical properties in HLW near-field for a long term. Centrifuge and X-ray CT model test

The objective of this paper is to evaluate the geomechanical properties of HLW near-field for a long term by the centrifuge and X-ray CT model test. The model specimen consists of rock mass, bentonite buffer and model waste. The specimen was enclosed with the pressure vessel and centrifuge model tests were conducted at 30 G of centrifugal force field with confining pressures and injection pressures. As results, 1.5 - 1.6 MPa for swelling pressure of the bentonite, approximately 2 mm for subsidence of the overpack, and strain of the bed rock were observed in 30 - 100 equivalent years. In the X-ray CT tests, the bed rock, bentonite and model waste were clearly distinguished in the CT images and it was observed that a gap between the disposal holes is buried by swelling of bentonite. (author)