Study of advection-dispersion calculation method by using the random-walk method for the purpose of application to biosphere assessment for geological disposal of radioactive waste

Itazu, Toru; Kato, Tomoko ; Maekawa, Keisuke  

Biosphere assessment, which is a part of safety assessment for geological disposal of radioactive waste, addresses the migration of radionuclide from underground to near the ground surface. Advection-dispersion calculation for this purpose must take into the consideration the following factors: long-distance migration of solute, a requirement to calculate the inflow of solute into the rivers or sea bed supposed to be the final position, demand to control numerical dispersion in heterogeneous field. In this study, we adopt the Random-Walk Method having functions required to biosphere assessment and developed a program available to groundwater analysis by using MODFLOW. The program is verified by comparison with the analytical solution and studied about application method to biosphere assessment.