Research for the erosion of buffer material with the vertical disposal concept, 4; Numerical analysis of inflow control into the disposal pits using discrete fracture network model

Atsumi, Hiroyuki*; Masumoto, Kazuhiko*; Ishii, Tomoko*; Jo, Mayumi*; Nakayama, Masashi ; Ono, Hirokazu 

In the vertical disposal concept of high level radioactive waste, it is important to evaluate influence of the groundwater inflow into the disposal pits against performance of buffer material as an artificial barrier because the inflow might cause the erosion of buffer material. The target of this study was to estimate the inflow control technique (e.g. grouting) around the disposal pits using numerical analysis. The model for the simulation should be a discrete fracture network model when the groundwater mainly flows along the fractures in the rock mass, therefore, the discrete fracture network model was selected to estimate the inflow control technique in this study. The results of numerical flow analysis showed that the effectiveness of grouting for the disposal pits and the impact of grouting for the other disposal pits or surrounding disposal tunnel could be evaluated quantitatively.