A probabilistic model for the simulation of radioactivity transport through a heterogeneous porous medium

The subsurface transport of radioactivity is critically governed by the nature of the medium. In general, the near earth surface medium is a mixture of a homogeneous (sand/soil) part and small stones sitting at few arbitrary locations. A probabilistic approach is adopted to estimate the locations of stones inside a 2D domain and the migration through such a medium for a given distribution is modelled. The entire process is repeated to arrive at a probabilistically averaged concentration value. Results show that the overall transport decreases systematically with the increase of heterogeneity of the medium. Next, simulations are carried out for different heterogeneity and different durations of the migration process. Here also a systematic trend is observed. Concentration corresponding to any in-homogeneity or time of migration falling within this range of modelling can be estimated by interpolation.