Source term and their consequences have been estimated for some postulated severe accident scenarios in a 220 MWe Indian Pressurised Heavy Water Reactor (IPHWR). Thermal-hydraulic analysis for the core and the containment has been studied with fission product transport within and outside the plant. The results form a data base to train a neural network based diagnostic tool useful for emergency planning and management. The paper describes in detail the assessment methodology, analyses for different events and the computed values of the doses to public.