Activation analysis for the HCPB blanket module in the European DEMO

The activity and decay heat inventories were assessed for the HCPB DEMO blankets making use of a code system that enables performing 3D activation calculations by linking the Monte Carlo transport code MCNP and the fusion inventory code FISPACT through an appropriate interface. The dedicated full scale geometry MCNP model of a 10° HCPB DEMO torus was adapted to the requirements for the coupled 3D neutron transport and activation calculations. The sensitivity analyses were performed to assess the effect of the homogenized geometry cells to the final results. The importance of the use of the impurities in the material definitions was pointed out and accounted for in the simulations. The activity of the HCPB blanket modules is dominated by the tungsten protecting layer up to one month after shutdown. After that it's dominated by the breeding zone mixture of Eurofer, breeder ceramic and beryllium pebbles with impurities. The decay heat generation in blankets is especially high in the casing that requires intensive cooling efforts for their treatment after the shutdown. The accumulation of the poisoning 239Pu could make complicated the recycling of the beryllium pebbles extracted from the blankets.