Study on modeling and analysis of groundwater flow with inverse analysis (Joint research)

In Japan, high-level radioactive waste (HLW) will be emplaced in a stable host rock formation deeper than 300 meters underground for geological disposal. It is important to understand heterogeneous distribution of hydraulic conductivity from the viewpoints of the safety assessment of geological disposal of HLW and construction of underground facilities. Inverse analysis based on the transient data is an efficient technique for estimating the heterogeneous distribution. In this study, numerical experiments with the adjoint state method and the ensemble Kalman filter method were carried out in order to understand effective method for application of these inverse analysis. As a result, the capability of each analysis technique was shown. (author)