Clarification of Tritium Behavior in Pb­Li Blanket System

In order to clarify the tritium behavior in Pb­Li blanket system, the solubility of hydrogen isotopes in the Pb­Li eutectic alloy was experimentally investigated. The effects of (i) Li preferential evaporation from Pb­Li, (ii) thermal convection in a quartz-glass reaction tube and (iii) difference in crucible materials between Al2O3 and W on the solubilities were discussed. Another important issue of the Pb­Li blanket system is to develop a new ceramic coating to decrease tritium permeation rate. Tritium permeation test was performed for Er2O3 coating on F82H. The permeation reduction factor achieved here was higher than 10 3 . Precise experiments were carried out to determine the solubility, diffusivity and permeability of hydrogen isotopes in Pb­Li eutectic alloy by means of a transient permeation method. The isotope effects in solubility and diffusivity between H and D were clarified. No isotope effect in solubility was observed between H and D, and the H diffusivity was 1.4 times larger than the D one. The ratio was near to a value predicted from the classical theory. Experiment using tritium is designed under the collaboration work with INL. [doi:10.2320/matertrans.MG201203]