Tritium permeation at 350°C through stainless steel wall of a vessel filled with deuterium-tritium gas of 6.1 × 106 Pa pressure was practically suppressed by Au plating of 20 μm thick applied to the outside surface. The apparent diffusivity of hydrogen through plated Au layer, derived from the experimental data, was 2 × 10-11 cm2/s for 470°C, which is 10-510-6 times smaller than what would be expected from values reported for wrought Au, and the apparent solubility was very significantly higher than similarly expected level. Gas analysis of the Au layer indicated that the effective suppression of tritium permeation is attributable to trapping of hydrogen by C contained in the Au as impurity. Adequate tightness against tritium leakage has been achieved by Au plating on a vessel used for loading glass microspheres with deuterium-tritium gas, intended for laser fusion targets.
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