DEMO tritium breeding performances with different in-vessel components configurations

This article presents a global study of the tritium breeding performances in DEMO for the two breeding blanket concepts helium-cooled pebble bed (HCPB) and water-cooled lithium lead (WCLL). In order to consider the impact of cut-outs in the breeding blanket to integrated plasma limiters and auxiliary systems a set of 22.5° sector models was elaborated for diverse geometry configurations. The cut-outs in the breeder blankets were implemented making use of simplified CAD models for limiters (central inboard, upper, equatorial mid plane and equatorial lower limits) as well as for EC and NBI systems. These models were converted into the MCNP geometry representations making use of SuperMC code. The TBR calculations were performed with MCNP code for all geometry models. Interference effects due to non-symmetric distribution of limiters and auxiliary systems around the torus are shown to be negligible making use of a dedicated 360° model. Therefore the total TBR can be calculated considering the separate results regarding the impact of the different In-Vessel Components (IVCs) included in the 22.5° models. The TBR decrease due to the allocation of all currently considered limiters and auxiliary systems is ∼11% and ∼10% for the HCPB and the WCLL blanket respectively. Depending on the TBRtarget value adopted in the DEMO project (assumed range being 1.02–1.05) the required TBR can vary from TBRreq = 1.13÷1.16 accounting for the impact of the integration of limiters and auxiliary systems.