Design of a tritium breeding blanket for volumetric neutron source

A water-cooled and austenitic stainless-steel-structured breeding blanket system is designed for a volumetric neutron source (VNS), based on a steady-state tokamak device. The designed VNS with super-conducting coils has a 4.5 m main radius and a total of 300 MW in fusion power. It yields the tritium consumption of approximately 10 kg per year with 50% availability. It is unrealistic to assume that this amount of tritium could be supplied by other nuclear facilities, therefore, tritium breeding with the VNS device itself should be accommodated. The capability of tritium breeding for the Li-Pb breeder is examined. Compared to ceramic breeding materials, in general, the Li17Pb83 breeder has the potential for a higher tritium breeding ratio. In addition, the compatibility of Li-Pb with water coolant and with structure material at low temperature and low flow velocity may be acceptable. The calculated local TBR in the present design reached 1.4 or more in the Li-Pb breeder with a sufficient thickness of the breeding zone. The temperature distribution in the breeding region of the Li-Pb blanket was controlled to avoid corrosion of the structure material, using a double-walled cooling panel. The net TBR might attain the acceptable value when only the outboard Li-Pb blanket is used, since the contribution of outboard blanket to tritium breeding is higher than its coverage.