Activation of breeder materials in the blanket of a (d,t)-fusion reactor

The present work analyses the activation behavior of two breeder materials in the blanket of a power generating (d,t)-fusion reactor: ceramic lithium orthosilicate (Li4SiO4) and eutectic lithium-lead (Pb - 17Li). The references for the analyses were two blanket concepts, which have been developed at the Forschungszentrum Karlsruhe within the European Fusion Technology program for a demonstration (d,t)-fusion reactor: a self-cooled liquid metal blanket with Pb - 17Li as a breeder/coolant with helium-cooled first wall (Dual Coolant Blanket Concept) and a helium-cooled solid breeder blanket with Li4SiO4 as a breeder and beryllium as a neutron multiplier (Breeder Outside Tube Blanket Concept). The analyses were performed based on a three-dimensional neutronic modeling. By coupling the Monte Carlo transport code MCNP with the fusion inventory code FISPACT from European Activation SYstem (EASY), a code system was developed which enables activation analyses for (d,t)-fusion reactor in a three-dimensional geometry. With this approach, the geometrical complexity of the tokamak-reactor and its neutronic behavior can be taken into account significantly reducing the model-related uncertainties. The reliability of the results is, therefore, determined by the uncertainties of the underlying differential data. The standard method of sensitivity and uncertainty analysis and a simple analytic approximation have been used to quantify the data related uncertainties. For this purpose, a code system has been set up based on the sensitivity/uncertainty code SUSD and the deterministic SN-transport code TWODANT. The basic activation behavior of the considered breeder materials, the time-dependent spatial distribution of activation quantities in the blanket, and the effects of impurities and sequential charged particle reactions (SCPR) have been analyzed. Important reactions and nuclides relevant for the activation of the considered breeder materials have been identified. The activation behavior exhibits substantial contributions from activated impurities at the intermediate and long cooling times relevant for recycling and disposal of the activated breeder materials. Nuclides induced through SCPR have substantial contribution to the activation of Li4SiO4. On the other hand, they are of no significance for the activation of Pb - 17Li. The contribution of the breeder materials activation to the total activity inventory and the total afterheat generation of the