Study on flow and mass transport through fractured sedimentary rocks (Contract research)

Shimo, Michito*; Kumamoto, So*; Karasaki, Kenji*; Sawada, Atsushi ; Maekawa, Keisuke  ; Sato, Hisashi

It is important for safety assessment of HLW geological disposal to evaluate groundwater flow and mass transport in deep underground accurately. The objective of this study is to expand the data of flow and mass transport properties in fractured sedimentary rocks, and to estimate these properties in larger scale rocks, such as in situ test scale, using the results of the laboratory tests and the borehole investigations. This study was carried out under the following three tasks: (1) laboratory hydraulic and tracer experiments using the rock specimens of Koetoi formation obtained at underground research facility under construction in the Horonobe area, (2) a numerical study on the influence that a difference of the groundwater flow velocity in the fractures gives a mass transport in the fractured sedimentary rocks, (3) a numerical study on the contributing factors to groundwater flow such as effect of low permeability layers.