Hydrogen isotopes permeation evaluation in the advanced material for nuclear fusion blanket use

Behavior of hydrogen isotopes such as permeation, diffusion, and dissolution infusion blanket materials were investigated from a viewpoint of the material development and a material design for a fusion reactor. Experiments were conducted with Reduced Activation Ferritic Steel (F82H) and various kinds of SiC materials at elevated temperature. To evaluate permeability of SiC materials and RAFM, deuterium gas permeability was measured using newly designed device. Permeation of hydrogen through RAFM was not significantly different from that of Austenitic Steel, however the temperature dependence of the permeability diffusivity, and solubility showed marked discontinuous change around 850 degree C. Change in crystal structure from bcc to fee is a suspected cause. The measurement of permeability of deuterium gas in Hexoloy and CVD SiC samples were attempted at the temperature above 800 degree C The permeability and deuterium diffusivity of Hexoloy is 2 orders of magnitude smaller than that of CVD SiC. On the pressure dependence of permeability, both linear and square-root dependence were seen.