Application of the Weibull Distribution Function in Cs-137 Vertical Migration Modelling

Radiocesium, as one of the most important radioactive released material from accident happening in nuclear installations, make a global attraction in radioecology community. Quantitative insight of its depth profile since the initial ground deposition has a direct impact on the future exposure pattern of the inhabitant living in contaminated areas. Among the available sophisticated and precise numerical models, there still exists a global interest to invoke a robust analytical counterpart including the main physico-chemical basis of radioactive species transport. Because of the more flexibility inherent in the Weibull distribution function, it can be adopted as a suitable alternative choice of the Gaussian distribution function for the analytical solution of the advection-dispersion equation. It has two adjustable parameters of the shape and scale which with them, we can manage reasonably the interpolation quality of the measured Cs-137 depth profile showing a local subsurface peak or a prolongation tail. In this research, using the measured Cs-137 depth profile data and numerical simulation results, we have shown that the Weibull distribution stay at trustable level to describe the time evolution of experimental Cs-137 depth profile.