Development of a helium-cooled divertor for Demo: thermohydraulic design and CFD analyses

A helium-cooled modular divertor concept with integrated heat transfer promoters is currently being investigated at the Forschungszentrum Karlsruhe within the framework of the European Power Plant Conceptual Study (PPCS). Design goals are to manage peak heat loads as high as 10 MW/m² and keep the temperatures in all components having a structural function within the design limits that are generally restricted by the operational temperature windows for refractory alloys and structural material. By using small modules, the thermal stresses are reduced. High heat transfer coefficients are achievable, while the coolant mass flow rate and, hence, the pressure loss as well as the pumping power can be kept rather small. The thermohydraulic performance was investigated by using different computational fluid dynamics (CFD) programs. The results were compared in order to establish a reliable basis for the simulations. They show good agreement.