Neutronic and thermo-mechanical analysis in support of the design of the water-cooled lead ceramic breeder breeding blanket concept for the EU DEMO

The Water-cooled Lead Ceramic Breeder (WLCB) Breeding Blanket (BB) concept is conceived in order to merge the Helium-Cooled Pebble Bed (HCPB) and the Water-Cooled Lithium Lead (WCLL) BB concepts, studied for a long time within the EUROfusion consortium, taking the best from each of them. The WLCB BB is characterised by the adoption of a solid breeder, molten lead as neutron multiplier and water at PWR conditions as coolant. Its design relies on the presence of actively cooled first wall and vertical stiffeners. Cassettes to clad functional materials are adopted as well. The ultimate scope is to develop a BB concept capable of fulfilling the high-level DEMO requirements with proven technology and acceptable risk level, overcoming the critical aspects characterising the WCLL and HCPB BB development. In this context, the University of Palermo is involved in the WLCB BB design in close cooperation with EUROfusion. Several architectures have been investigating over the years, to find the best in terms of heat removal, tritium breeding, shielding, structural integrity and manufacturing. In this paper, neutronic and thermo-mechanical analysis to sustain the WLCB BB design based on the baseline architecture are presented. From the nuclear standpoint, analysis to calculate the deposited heat power has been performed, considering either Eurofer or SiC as cassettes structural material. Afterwards, thermo-mechanical analysis of the Central Outboard Blanket segment Top Cap (TC) region has been performed, to obtain a robust layout of such a critical region under steady-state nominal conditions. To this scope, the impact of the non-ideal contact between cassettes and structural components on the segment thermo-mechanical performances has been assessed in detail. The obtained outcomes allowed highlighting the potential benefits of adopting SiC instead of Eurofer for the cassette and suggesting design improvements to increase the WLCB BB neutronic and thermo-mechanical performances.