Abstract
Bentonite has been studied as the buffering materials in the project of the low-level radioactive waste disposal and high-level radioactive waste disposal, since bentonite has high abilities of water interception, self-sealing, absorption, chemical buffring and material migration retardation. In order to realize those abilities, it is prefer to install bentonite under the high density condition. The granular bentonite was developed which utilize the different size of bentonite particles, it make it possible to realize the easy installation under the high density condition.
In this study, swelling process of the bentonite is visualized and analyzed by X-ray CT method. The soaking tests of bentonite under the displacement constraint using acrylic molds were conducted during over 200 days. The swelling and homogenization process during soaking tests were visualized, and the soaking and swelling process were analyzed from X-ray CT image data. The parameters, such as water content ratio, wet density and dry density were also measured and the fundamental properties of the bentonite were verified. It was also found that those parameters can be accurately evaluated from X-ray CT image data. The water permeation tests under the displacement constraint and displacement free conditions were also conducted. The evaluated intrinsic permeability were low enough in both conditions, and it was confirmed that the displacement constraint does not gives crucial effects to the permeability of bentonite.
