Effects of time-dependent deformation of shale on the integrity of a geological nuclear waste repository

Safety assessment of geological nuclear waste repositories is essential for the permanent disposal spent fuels and high-level radioactive waste. The long-term integrity host rock as well engineered barrier system (e.g., bentonite buffer) surrounding canisters particular importance decay heat from canisters, which will last over thousands years, significantly disturbs thermo-hydromechanical (THM) state repository. In this study, THM coupled simulations were carried out to investigate effect time-dependent deformation (i.e., creep) shale on a generic subsurface Norton-Bailey creep model, also known Lemaitre-Menzel-Schreiner was employed simulate power-law type that observed in shales. TOUGH-FLAC simulator modeling objective study assess different shales high vs. low shale) stress permeability changes Results show potential advantages constructing shale, deviatoric levels formation decreased zero 100 years since emplacement undamaged, intrinsic 10,000 years. Also, mean effective buffer increased by 100% case relative at due creep-induced contraction tunnel. However, earlier periods 1000 years), twice smaller than case, shows tradeoff between intermediate- (∼1000 years) (>10,000 compaction depending characteristics shale.