Passive system for cooling the inboard region in case of a severe accident

Previous calculations performed for different fusion reactor concepts indicated that the absence of an effective heat sink for the after-heat in the inboard region can cause concerns for the temperatures reached in case of a severe accident. This can compromise the mechanical stability of the vacuum vessel (VV) or cause unacceptable temperatures of the inboard in-vessel components with consequence in the overall safety strategy. This paper describes a design solution that has been proposed for the European Helium Cooled Solid Breeder Reactor that allows transporting the heat from the inboard to the outboard side with a passive cooling system located in the VV and based on natural circulation of liquid lead. The presented calculations aim to demonstrate the feasibility and effectiveness of such a system. The presented results have been obtained for a geometry and parameters based on a particular reactor, nevertheless the system can be adopted for a large variety of reactor concepts being relatively independent of a particular blanket or maintenance schema.