The assessment of the 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, progresses for routine releases were done and in the EMRAS II programme a dedicated working group (WG 7 _ “Tritium” Accidents) focused on the potential accidental releases (liquid and atmospheric pathways). The progresses achieved in WG 7 were included in a complex report _ a technical document of IAEA covering both liquid and atmospheric accidental release consequences. A brief description of the progresses achieved in the frame of EMRAS II WG7 is presented.  Further needs of the processes understanding and the experimental efforts are emphasised.