Component-Level Tritium Transport Modelling of a Stellarator Ceramic Breeder Blanket

The helium-cooled pebble bed (HCPB) breeding blanket is one of the most extensively studied blanket concepts for a future fusion power plant. Modelling the transport of tritium within the blanket is essential for assessing both plant safety and tritium-extraction performance. This presentation demonstrates how tritium transport in an HCPB blanket can be modelled using FESTIM v1, an open-source finite-element code for hydrogen-isotope transport. It introduces the main physical processes involved and discusses how they can be represented within a component-level transport model. The presentation focuses on three modelling challenges. The first is the representation of tritium retention and release within the ceramic breeder pebbles. The second concerns the treatment of the pebble bed as a porous medium, including its influence on gas-phase transport and inventory. The third is the definition of an effective solubility for gaseous hydrogen isotopes, enabling gas transport to be represented consistently within FESTIM v1.