Transfer of 137Cs from soil to grass--analysis of possible sources of uncertainty.

On the basis of experimental data on the fallout of 137Cs from the Chernobyl accident, a statistical analysis was made of possible values of the coefficients of transfer via the soil-grass pathway. Model calculations of the possible radionuclide concentration in milk are performed by the Monte Carlo method using the probability distribution function obtained. It is shown that not only our limited knowledge and the possible diversity of the external conditions, but also the very nature of the phenomenon under consideration, make it desirable to switch from a deterministic to a stochastic formulation of the model. The fact that the dependence of the soil-to-grass radionuclide transfer coefficients on the initial concentration in soil might be non-linear in character is an indication of the limitation of the conventional linear model.