Modelling Of Diffusion And Trapping Of Hydrogen Isotopes In Ss316l Steel H/F CEA

Stainless steel 316L is used in tokamaks such as WEST and ITER and interacts with the hydrogen isotopes that are involved in the fusion reaction. During long plasma operation, the teams operating WEST suspect that increased temperature on non-actively cooled elements triggers hydrogen outgassing, which perturbates the plasma. ITER is also looking at this issue for its start-up. To better understand this phenomenon, experimental analyses have been performed at IRFM using two devices (permeation and thermodesorption). Using these results, desorption and permeation kinetics have been evaluated for this material with the help of modelling tools.

The objective of this intership work is to use the experimental results to complete the work that has been started by the team and obtain hydrogen isotopes diffusion and trapping parameters relevant to this nueance of steel. To that end, the diffusion-trapping code MHIMS will be used to reproduce experiments. A parametric study will be conducted to evaluate the importance and role of each parameter on the possible models. These models will be critiqued by comparing them to additional experimental data, taken from existing literature. The preferred models will then be used to evaluate hydrogen retention and outgassing for typical WEST and ITER scenarios.