Coupled hydro-transport analysis study of geochemical reaction due to unsaturated around the disposal tunnel; Application of the coupled Thermo-Hydro-Mechanical and Chemical (THMC) processes model/analysis code in the geological disposal for the high-level radioactive waste

Suzuki, Hideaki; Fujisaki, Kiyoshi; Fujita, Tomoo 

The development of excavation disturbed zone (EDZ) around the disposal tunnel affects such as the corrosive environment of the over-pack and environmental condition of the nuclear species migration on the geological disposal for the high-level radioactive waste (HLW). It is necessary to consider aftermath of EDZ in initial condition of the realistic numerical simulation of the long-term behavior of near-filed HLW repository after emplacement of engineered barrier system. This report presents the analysis assessment geochemical reaction with the development of the unsaturated zone around the disposal tunnel by developed the coupled Thermo-Hydro-Mechanical and Chemical (THMC) processes model / analysis code. As a result, the THMC processes analysis model apply a change of the solution composition by degasification of the carbon dioxide gas to the pore water and the change of the oxidation-reduction potential due to unsaturated zone around the disposal tunnel.