Thermal impacts on the erosion of compacted bentonite under flow rate

Abstract

Compacted bentonite is widely used as a filling and barrier material for underground storage of spent nuclear fuel waste due to its favorable properties. Over its design life, this compacted clay may be exposed to groundwater from the surrounding host rock. Depending on the modeling approaches and assumptions, the temperature to which the compacted bentonite will be exposed can vary. This paper presents the findings of laboratory investigations on the erosion of compacted bentonite at ambient temperature (26 °C) and elevated temperature (80 °C) temperatures. The compacted bentonite samples, with dry densities of 1.72 g/cm³ and 1.73 g/cm³ were subjected to erosion under a flow rate of 0.22 ml/min at 26 °C and 80 °C, respectively. The dynamic light scattering (DLS) method was employed to measure the size and quantity of the eroded particles. The amount of daily erosion and the size of the eroded particles were determined from effluent samples. The results indicate that the amount of eroded bentonite particles increased significantly with increasing temperature. Additionally, as temperature increased, the size of bentonite particles in the effluent decreased within a specific range. At 26 °C, particle sizes ranged from 59 to 6358 nm, whereas at 80 °C, the particle size distribution narrowed.