The assessment of environmental impact of tritium release from nuclear facilities is a topic of interest in many countries. In the IAEA's Environmental Modelling for Radiation Safety (EMRAS I) programme, there have been done progresses for routine releases and in the present, a dedicated working group (WG 7 - “Tritium” Accidents) of EMRAS II programme is focused on the potential accidental releases (liquid and atmospheric pathways). This working group tries to develop more robust models in international cooperation, analyzing the processes involved concerning tritium transfer in the environment. Briefings of the actual progresses in this working group, as well as other tritium studies, are presented. Romania, having CANDU reactors, is interested in both liquid and atmospheric accidental release consequences. Progresses done in the frame of EMRAS are presented, as well as tritium washout, transfer in aquatic media, and transfer to farm animals and birds. An extension of the metabolic model for tritium transfer applied to humans is briefly described. Further needs of process understanding and experimental efforts will be noted.