radiation dosimetry model HYDRUS HYDRUS is a software package for modelling water flow and solute transport in variably saturated porous media, applied at BfS for simulating radionuclide migration in soils and groundwater systems relevant to radioactive waste disposal and contaminated land assessment. It enables prediction of radionuclide transport and breakthrough curves under realistic hydrological conditions. The software is freely available and not subject to committee review requirements. Located at BfS Federal Office for Radiation Protection, SW 1.6. http://www.bfs.de Paul Schofield