Study on flow and mass transport through fractured sedimentary rocks, 2

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

It is important for safety assessment of HLW geological disposal to evaluate groundwater flow and mass transport in deep underground. The fractures might dominate flow and transport even though it is soft sedimentary rocks. In this study the following three tasks were carried out. Firstly, non-sorbing tracer experiments were carried out. The obtained breakthrough curve was interpreted and mass transport parameters, such as longitudinal dispersivity, matrix diffusion coefficient, transport aperture, were obtained. Secondary, several cases mass transport simulations using single fracture model that the hydraulic aperture, transport aperture, and porosity is different were performed to study on the influence that a difference of the aperture and porosity gives a mass transport in the fractured sedimentary rocks. Finally, groundwater flow was simulated to estimate the flow direction and recharge from the surface using the temperature distribution data obtained in Horonobe boreholes.