Dose to the population from unit releases of tritium and activation products in EU DEMO

Releases of tritium and activation products may occur during normal operation conditions or during incidents and accidents of the EU DEMO. In particular unit source terms allow to compare the consequences for different materials in a well-defined manor. One gram of tritium in form of HT and HTO as well as six different activated materials identified in DEMO were investigated. For accidental releases, deterministic and probabilistic release scenarios were defined and evaluated with two assessment models. Under normal operation conditions, uniform releases of one gram over one year were assumed. Doses to the most exposed individual in particular at 1 km distance from the source were assessed. Further, concentrations in several key food products were calculated. Tritium in form of HTO dominates all results. For activation products, Tungsten dust and Activation Corrosion Products (ACP) show in most cases highest values, however, clearly below tritium. The simulations demonstrated the importance of the ingestion pathways. Even if doses from accidental releases are generally rather low and far below criteria for early countermeasures, HTO concentrations in food products may exceed limits proposed by the World Health Organisation (WHO) up to several tens of kilometres. For normal operation releases, doses are in the order of one micro Sievert and concentrations in food products below limits from 1 km onwards.