Modelling radionuclide distribution and transport in the environment

Mathematical models of radionuclide distribution and transport in the envir onment have been developed to assess the impact on people of routine and ac cidental releases of radioactivity from a variety of nuclear activities, in cluding: weapons development, production, and testing; power production; an d waste disposal. The models are used to estimate human exposures and doses in situations where measurements have not been made or would be impossible or impractical to make. Model results are used to assess whether nuclear f acilities are operated in compliance with regulatory requirements, to deter mine the need for remediation of contaminated sites, to estimate the effect s on human health of past releases, and to predict the potential effects of accidental releases or new facilities, This paper describes the various ap plications and types of models currently used to represent the distribution and transport of radionuclides in the terrestrial and aquatic environments , as well as integrated global models for selected radionuclides and specia l issues in the fields of solid radioactive waste disposal and dose reconst ruction. Particular emphasis is placed on the issue of improving confidence in the model results, including the importance of uncertainty analysis and of model verification and validation. (C) 1999 Elsevier Science Ltd. All r ights reserved.