Influence of Chromium Oxide Layer on Surface Tritium Contamination of Type 316 Stainless Steel

Sheet type specimens of type 316 stainless steel covered by Cr oxide layers were exposed to tritium gas at 300 °C together with the specimens covered by Fe-rich oxide layers and pure Fe specimens to compare tritium behaviors in oxide films with different Cr contents. Tritium concentration in the oxide layers decreased with increasing Cr content due to reduction in concentrations of hydroxyl species and adsorbed water. In addition, release rate of tritium from Cr oxide layers was larger than that from Fe-rich oxide layers. It was concluded that preparation of thin Cr oxide layer is effective to reduce surface tritium contamination of austenitic stainless steels.