Development of a model for the mass loss rate of chemical erosion in fracture intersection with the deposition hole

Abstract

Abstract The erosion of bentonite buffer in a fracture intersecting a deposition hole will affect the safety function. The purpose of this study was to build up a model which was to predict the rate of erosion of buffer/backfill, and this research focused on the KTH model which was developed by SKB. The KTH model consists of fluid pressure, sodium concentration, and smectite volume fraction, which is governed by Darcy’s Law and advection-diffusion equations respectively, and the mutual dependencies of these variables were considered. This model was implemented using the COMSOL Multiphysics, and the results show the different behavior of sodium concentration and smectite in various seeping water velocity, the erosion rate increases with the seeping water velocity, but the distance to the smectite rim border decreases with the water velocity. The KTH considers the relationship between sodium and smectite, and with scalability. it lays a foundation for the evaluation buffer/backfill mass loss by erosion.