Recent progress in the WCLL breeding blanket design for the DEMO fusion reactor

The water-cooled lithium lead breeding blanket is one of the candidate systems considered for the implementation in the European Demonstration Power Plant (DEMO) nuclear fusion reactor. This concept employs lithium-lead liquid metal as tritium breeder and neutron multiplier, water pressurized at 15.5 MPa as coolant, and EUROFER as structural material. Current design is based on the Single Module Segment approach and follows the requirements of the DEMO-2015 baseline design. The module is constituted by a basic toroidal-radial cell that is recursively repeated along the poloidal direction where the liquid metal flows along a radial-poloidal path. The heat generated by the fusion reactions is extracted by means of separate cooling systems for the breeding zone and the first wall. A back supporting structure is dedicate to withstand the loads of the module during normal and off-normal operations. Water and lithium-lead manifolds are integrated with primary heat transport and tritium extraction systems. The status of the conceptual design is presented, critically discussing its rationale and main features as supported by neutronic, thermal-hydraulic, magneto-hydrodynamic and thermo-mechanic analyses. Recent results are outlined, pointing out open issues and development needs