Study of Outgassing and Removal of Tritium from Metallic Construction Materials of ITER Vacuum Vessel Components

Abstract

The subject of this study is the evaluation of tritium outgassing and removal from metals such as tungsten, beryllium, stainless steel, and copper alloy. In addition, a composite sample assembled from tungsten, copper alloy, and stainless steel was also studied. Samples of individual materials and composite samples were of thicknesses and compositions representing the internal components of the ITER vacuum vessel. The samples of materials were loaded with tritium by exposure to a gaseous tritium-deuterium mixture (about 1:1) at a temperature of 473 K and a pressure of about 0.05 MPa. The rate of outgassing was measured at temperatures of about 295, 308, and 323 K under static or dynamic atmospheres either of ambient air or dry air or argon. The study allows recommendation of conditions for storage of in-vessel components and reduction of the rate of tritium outgassing. The metals’ samples were also subject to study of tritium removal by thermal desorption under purge with argon containing 5 vol % of hydrogen. The study has demonstrated that this detritiation procedure allows for removal of large portions of the tritium inventory and substantial reduction in tritium outgassing rates.

Keywords:

• Tritium in metals
• metals detritiation
• fusion reactor

Acknowledgments

This work was funded by the ITER Organization. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization.