Possibility of tritium self-sufficiency in low aspect ratio tokamak reactor with the outboard blanket only

Hayashi, Takao; Tobita, Kenji; Nishio, Satoshi; Sato, Satoshi; Nishitani, Takeo; Yamauchi, Michinori

We have studied the possibility of tritium self-sufficiency with the outboard blanket only in low aspect ratio tokamak reactor to simplify the inboard structure in high magnetic field. The tritium breeding ratio (TBR) of the outboard blanket increases by applying the inboard reflector working as a neutron multiplier such as lead and beryllium. Assuming that the coverage of the breeder zone to plasma facing components is 0.78, the requirement of local TBR is above 1.35. The local TBR calculated with both the inboard reflector of lead and the outboard blanket using beryllium multiplier and LiO breeder is larger than 1.35 for aspect ratios smaller than 2.9. These results indicate there is a solution for tritium self-sufficiency using the outboard breeding blanket only in low-A tokamak reactor when the appropriate inboard reflector and outboard blanket are adopted. In case both inboard and outboard blankets are applied, the total TBR with the combination of LiO and Be is more than 1.5. However, BeTi and LiTiO are recommended from the viewpoint of safety, and the TBR with the combination is slightly larger than 1.35 for aspect ratios from 2 to 4.