The migration of radionuclides in the
U-series in soils and their up-take by plants is of interest in various contexts, including the geological disposal of radioactive waste and the remediation of former sites of uranium mining and milling. In order to investigate the likely patterns of behaviour of U-series radio-nuclides being transported upward through the soil column, a detailed soil-plant model originally developed for studying the behaviour of radionuclides in soil-plant systems has been adapted to make it applicable to the U-series. In this paper, a brief account is given of the mathematical basis of the adapted model and key parameters are identified and then estimated. Hydrological data appropriate to a situation in which upwelling groundwater interacts with meteoric water in the soil zone are also selected, using meteorological data from a former uranium mining site in Spain as a key input. On this basis, a reference calculation are defined and run for a unit input rate of either U or Ra at the base of the soil column and for a simulation period of 5,000 years. Results for this case are then used to comment on potential long-term patterns of behaviour of U-series radionuclides in soils and their uptake by plants.