Modelling of Tritium Behaviour in the Environment

In view of the operation of fusion reactors the release of tritium may play a dominant role during normal operation as well as after accidents. Because of its physical and chemical properties which differ significantly from those of other radionuclides, the model UFOTRI for assessing the radiological consequences of accidental tritium releases has been developed. It describes the behaviour of tritium in the biosphere and calculates the radiological impact on individuals and the population due to direct exposure and by the ingestion pathways. Processes like the conversion of tritium gas into HTO in the soil, re-emission after deposition and the conversion of HTO into organically bound tritium are considered. Probabilistic calculations with UFOTRI show a spectrum of the radiological impact together with its probability of occurrence.