Safety assessment of radioactive waste disposal On the basis of a reference biosphere methodology, biosphere modelling has been developed and applied in long-term safety studies for performance assessment of nuclear waste disposals. Climate Change and Environment © PhotoDisc The BioMoSA project focused on the development of site-specific biosphere models for performance assessment of nuclear waste disposals. Within this context, the description and characterisation of five different European locations with varied environmental and agricultural conditions was originally provided. Most commonly radionuclides used in performance assessment studies, such as 36Cl, 79Se, 99Tc, 129I, 135Cs, 226Ra, 231Pa, 230Th, 237Np, 239Pu, and 238U were selected for investigation. For each location, a site-specific biosphere model was generated with parameters chosen to be element -independent (human consumption rates) and element -dependent (migration of radionuclides in soil). Each site-specific model was applied in each location selected resulting in calculations of annual individual doses, identifications of key processes and parameters and estimations of the results' uncertainties. The results were normalised to a specific activity concentration level for each of the radionuclides considered for comparison purposes. All features and processes of the site-specific models were included in a more generic model developed for the same purpose. This was tested to model the five locations and the results derived were in good agreement with those coming from the in-site specific models. Therefore, this model could be used for a common-basis investigation of different sites with varied climates and geosphere/biosphere interfaces. The tool is available for use provided that a software licence for the numerical solution method is given. Furthermore, the BioMoSA project also resulted in key conclusions related to the development of site-specific assessment tools. All project results are expected to significantly contribute in the minimisation of the uncertainty involved in the long-term dose assessment of population groups. These results will improve the public confidence in such studies related to the assessment of potential radiological risks. They will also provide authorities and regulator bodies with sound-basis guidelines for performance assessments of repository systems.