In the Fukushima nuclear accident, the contaminated water with radioactive nuclides are a serious problem. In order to prevent spreading of the pollutants and make an effective arrange of barrier, a better model of migration is desired. Specifically,  a model that enables us to know the whole site from measurements at a small part of the site. One of the candidates of those models is the Continuous-Time Random Walk model (CTRW) which leads to a fractional order (in time) of a differential equation.  We present some experimental findings and simulation results and discuss the appropriateness of the model.