Mobilisation and migration of decay series radionuclides - a basis of estimation radiation exposures at remediation sites of former uranium mining

For the assessment of radionuclides dissolved in groundwater with respect to the remediation measures at the former uranium mine Koenigstein three different types have to considered. Only in special cases the migration of radionuclides can be described as a retarded and decaying tracer (''isolated migration''). The dissolved concentrations of the short-lived nuclides do not correspond to the radioactive equilibrium. Rather, they are determined by the water-rock interaction. For a homogeneous aquifer an analytical solution of the ''coupled migration'' can be derived and easily used in radioecological models. A third process which has been widely neglected till now may occur in special cases. If the source releases water of significantly changed chemical composition (e.g. acid mine water), the radionuclide composition at a user site will change after this water has arrived (''induced mobilisation''). The assessment of the latter mechanism requires a new approach of determining parameters. (orig.)