Near surface disposal of low and intermediate level radioactive waste is probably the best solution for a long term radioactive waste management today. For safety assurance all near surface disposal aspects and evolution scenarios should be reviewed and analyzed including repository design and site selection, because releases of radionuclides from the repository into the environment cause radiation exposure to the public. Mechanisms of 14C, 129I and 137Cs transportation from the repository into the environment, modelled for the hypothetical radioactive waste disposal facility in Lithuania, are investigated and the results of effective dose calculations for the main exposure pathways are discussed in this paper. The RESRAD-OFFSITE code has been used in this study for modelling purposes. It is shown that the radionuclide transport time into the environment, its radioactive contamination and the radiation exposure to the public mostly depends on the mobility and sorption properties of radionuclides and on the appropriate transport pathways from the repository into the environment.