Tritium recovery from solid breeder blanket by water vapor addition to helium sweep gas

Kawamura, Yoshinori; Iwai, Yasunori; Nakamura, Hirofumi; Hayashi, Takumi; Yamanishi, Toshihiko; Nishi, Masataka

Adding some amount of hydrogen to the helium sweep gas is effective for tritium extraction from blanket, but it causes permeation of tritium to a cooling system. In the design study of a demonstration reactor in JAERI, tritium leakage has been estimated to be about 20% of bred tritium under typical sweep gas conditions. If these tritiums are recovered under the ITER-WDS condition, tritium leakage limitation has to be less than 0.3% of typical case. Water vapor addition to the sweep gas is effective not only for blanket tritium extraction but also for permeation prevention. The reaction rate of isotope exchange is larger than the case of H, and the equilibrium constant is also expected to be about 1.0. When the H/T ratio is 100, tritium inventory of breeder material is larger than the case of H addition. However it is not so large. In case of HO sweep, separation of tritiated water from helium seems to be easyer, but the process that changes HTO to HT is necessary.