A smart three-loop fuel cycle architecture for DEMO

Abstract In the framework of the EUROfusion Programme the EU is preparing the conceptual design of the fuel cycle for a pulsed fusion DEMO. Over the last years, a smart fuel cycle architecture has been developed, driven by the need to reduce the tritium inventory to an absolute minimum. To achieve this goal, batchwise processes used in the fusion fuel cycle so far were replaced by continuous processes wherever possible. This includes the change from discontinuous cryopumping to mercury based continuous vacuum pumping with zero demand on cryoplant power, and the introduction of temperature swing absorption processes for isotope separation in the tritium plant instead of large cryogenic distillation columns with tritiated liquid hold-ups. To circumvent handling of high inventories of tritium-bearing liquid fuel in cryogenic distillation columns of the tritium plant, superpermeable metal foils will be installed in the divertor ports of the vacuum vessel to extract pure DT continuously from the exhaust gas. Direct internal fuel recycling takes place via the pellet injection system. The paper discusses the design drivers and limitations, and describes the development status of the novel technologies.