Conceptual Design of Solid Breeder Blankets for Fusion Pilot Plants

Demonstrating high-grade heat extraction, tritium self-sufficiency, and structural reliability of breeding blankets remains a key technological challenge in progressing from International Thermonuclear Experimental Reactor (ITER) toward demonstration power plant (DEMO)-class fusion reactors. This work investigates solid breeder blanket design options for a fusion pilot plant (PP) with a fusion power of 300 MW. Three solid breeder configurations are considered: a vertically layered sandwich-type blanket with distinct ceramic breeder (CB) and beryllium multiplier regions; a radially stacked variant introduced as an alternative geometric arrangement; and a mixed pebble-bed concept that replaces beryllium with titanium beryllide (Be12Ti) and adopts tube-based cooling rather than plate-based coolant channels. Thermal–hydraulic and structural assessments were carried out using computational fluid dynamics (CFD) and finite-element simulations in ANSYS to evaluate temperature fields, coolant performance, and mechanical behavior under nominal operating conditions. The mixed bed configuration demonstrates higher average breeder temperatures ($\sim\!660~^{\circ }$C) compared to the sandwich-type blanket ($\sim\!565~^{\circ }$C), while remaining below material limits. Helium outlet temperatures of$\sim\!\!\!470~^{\circ }$C and tritium breeding ratios in the range of 0.72–0.73 were obtained for the evaluated concepts. Structural evaluation based on RCC-MR criteria confirms that both analyzed configurations meet primary stress limits, with peak stresses occurring locally at edges and corners. Overall, this study provides a comparative assessment of solid breeder blanket concepts suitable for near-term fusion PP deployment and identifies key areas for further development, including full 3-D neutronic validation, coolant flow, and structural refinement.