Development of Experimental System to Measure Waster Suction of Compacted Bentonites beyond 100 °C

The compacted bentonite buffer is one of the most important components in an engineered barrier system(EBS) to dispose of high-level radioactive waste (HLW) produced by nuclear power generation. The design temperature of the bentonite buffer is below 100 °C. However, if the design temperature can be increased above 100 °C, the disposal area can be reduced. For this reason, it is necessary to investigate its properties at 
temperatures above 100 °C to increase the target temperature of the buffer. Although some studies have investigated the thermal-hydraulic properties above 100 °C, few have evaluated the water suction of compacted bentonite. Therefore, this study developed experimental system to measure water suction above 100 °C, and measured relative humidity for compacted Korean bentonite between 25 and 150 °C with initial saturations of 0, 0.22, and 0.47 under constant saturation conditions. Water suction decreased as the temperature increased. In particular, there was an approximately 5–20% decrease in the water suction between 100 and 150 °C.