Advancements in the HELIAS 5-B breeding blanket structural analysis

•The proposed segmentation for the far end regions of a HELIAS 5-B breeding blanket half sector has been assessed.•A refined FEM model has been set-up.•A sensitivity analysis on the main design assumptions has been performed.•A 3D temperature profile has been imposed.•Results encourage the continuation of the design on the basis of the proposed segmentation strategy. Within the framework of EUROfusion consortium, the work package S2 aims at developing the HELIcal-axis Advanced Stellarator (HELIAS) as a possible long-term alternative to a tokamak DEMO. From the plasma physics standpoint, the HELIAS 5-B machine is the most promising concept. It is a large 5 field period stellarator reactor directly extrapolated from Wendelstein 7-X (W7-X), the largest stellarator reactor currently run by W7-X team [1]. Researches are currently ongoing at KIT in order to attain a preliminary design of the HELIAS 5-B breeding blanket (BB), taking into account as initial input the design experience acquired in the pre-conceptual design phase of the tokamak DEMO BB. To this end, the Helium-Cooled Pebble Bed (HCPB) and the Water-Cooled Lithium Lead (WCLL) BB concepts have been considered, focusing on the investigation of the suitability of their main structural features to the stellarator geometry. In this regard, possible design constraints coming from the Remote Maintenance have to be fulfilled in order to better orient the blanket segmentation. In the present work, a more sophisticated assessment of the BB modules structural behavior has been performed. Attention has been also paid to the refinement of the numerical models so far adopted, investigating the impact of the major assumptions, such as Vacuum Vessel temperature and equivalent Young’s Modulus, on the obtained results. To this purpose, dedicated parametric assessment has been carried out and discussed in this work. The obtained results are herewith presented and critically discussed, giving an overview of the follow-up of this activity.