Damage study for various materials at the first wall of a magnetic fusion reactor using protective liquid wall

A new magnetic fusion reactor design called APEX uses a liquid wall between fusion plasma and solid first wall to reach high neutron wall loads and eliminate the replacement of the first wall structure during the reactor's operation. In this paper, the radiation damage behavior of various first wall materials (W–5Re, V–4Cr–4Ti and SiC/SiC composite) was investigated in the APEX blanket where a protective liquid wall of 75% LiF–23% ThF4–2% 233UF4 was considered. Tritium breeding potential of this salt with respect to the investigated structural materials was also examined in this blanket. Neutron transport calculations were carried out with the aid of the code, SCALE4.3 by solving the Boltzmann transport equation. Computations were performed with respect to the liquid wall thickness to determine the effective thickness satisfying both the radiation damage and the tritium breeding criteria. Numerical results showed that the flowing wall consisting of 75% LiF–23% ThF4–2% 233UF4 with a thickness of ∼35 cm and ∼50 cm would be required to extend the lifetime of the first wall to ∼30 years and to supply sufficient tritium to the (DT) fusion driver for W–5Re and V–4Cr–4Ti, respectively whereas, SiC/SiC composite would require a flowing wall thickness of >60 cm to comply with both the damage and the tritium limits.