Study on groundwater flow system in a sedimentary rock area; Regional groundwater analysis

Munakata, Masahiro ; Namekawa, Maki; Sakai, Ryutaro; Kimura, Hideo

In the safety assessment for a geological disposal of long-lived radioactive waste such as high-level radioactive waste and TRU waste etc, it is important to estimate radionuclide migration to human society associated with groundwater flow. Japan Atomic Energy Agency (JAEA) has started to investigate a sedimentary rock area in the Yoro river basin, in Chiba Prefecture. The analytical study on regional groundwater flow system was performed by numerical code using FEM. As a result, a range of flow rates was estimated from 0.5 m/y to 30.0 m/y in this region and frow direction was generally from south-east to north-west. These numerical results show the local and regional flow system is reasonable to the observed data.