Permeation behavior of gaseous tritium through the assembly composed of Zr and Al₂O₃ simulating Li rod

For starting up a fusion reactor stably, the tritium production by the nuclear reaction of neutrons and lithium in a high-temperature gas-cooled reactor has been studied. In order to suppress the migration of tritium to the whole reactor, it is important to design a Li rod with tritium confinement function and understand tritium behavior. A Li rod structure consisting of Zr - LiAlO₂ - Zr - Al₂O₃ was proposed, and an assembly simulating proposed Li rod was fabricated. In the previous work using tritium gas containing mainly HTO rather than HT, the present authors succeeded in confining tritium in the assembly at 700 ℃ for 87 h. In this work, tritium gas containing mainly HT rather than HTO was supplied to the assembly, tritium permeation behavior was observed. Unlike the case of HTO, tritium permeated immediately after the introduction of HT. This result indicates that the chemical form of tritium significantly affects tritium confinement performance of the Li rod.