Tritium permeation behavior through pyrolytic carbon in tritium production using high-temperature gas-cooled reactor for fusion reactors

• Published in: Nuclear materials and energy Vol. 9; no. C; pp. 524 - 528
• Main Authors: Ushida, H., Katayama, K., Matsuura, H., Yamamoto, R., Fukada, S., Goto, M., Nakagawa, S
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2016; Elsevier
• Subjects: Hydrogen permeation; Pyrolytic carbon; Tritium permeation barrier; Hydrogen permeation; Tritium permeation barrier; Pyrolytic carbon
• ISSN: 2352-1791; 2352-1791
• DOI: 10.1016/j.nme.2016.09.004

•Hydrogen permeation experiments through a PyC-coated isotropic graphite tube were conducted.•Hydrogen permeation flux through PyC in a steady state is proportional to the hydrogen pressure.•Obtained hydrogen permeability in PyC is larger than that in Al2O3.•Obtained hydrogen diffusivity in PyC is smaller than that in Al2O3. Under tritium production method using a high-temperature gas-cooled reactor loaded Li compound, Li compound has to be coated by ceramic materials in order to suppress the spreading of tritium to the whole reactor. Pyrolytic carbon (PyC) is a candidate of the coating material because of its high resistance for gas permeation. In this study, hydrogen permeation experiments using a PyC-coated isotropic graphite tube were conducted and hydrogen diffusivity, solubility and permeability were evaluated. Tritium permeation behavior through PyC-coated Li compound particles was simulated by using obtained data. Hydrogen permeation flux through PyC in a steady state is proportional to the hydrogen pressure and is larger than that through Al2O3 which is also candidate coating material. However, total tritium leak within the supposed reactor operation period through the PyC-coated Li compound particles is lower than that through the Al2O3-coated ones because the hydrogen absorption capacity in PyC is considerably larger than that in Al2O3.