Prediction of the migration of radionuclides to the boundary of a shallow land burial trench

A general model which predicts the source term, radionuclide release rate, as a function of water flow, container degradation rate, waste form leach rate, and radionuclide migration rate from a low-level waste shallow land burial trench is being developed. This paper discusses modeling radionuclide migration, one component of the source term. Simulations of radionuclide transport from a generic shallow land burial trench have been performed for a range of water flow rates, dispersivity values, and distribution coefficients. For the modeling assumptions used and the range of parameters tested, the water flow rate plays the major role in redistributing radionuclides within the trench, except in the case of extremely high dispersion. Dispersion was always found to play a significant role in determining transport. This was particularly apparent upstream from the source. Sorption decreased the magnitude of the radionuclide concentration and had the apparent effect of reducing the velocity with which the radionuclides were transported. Diffusion was found to be unimportant in determining radionuclide transport