Numerical simulation by finite element modelling of diffusion and transient hydrogen trapping processes in plasma facing components. (May 2019)

• Record Type: Journal Article
• Authors: Benannoune, S.; Charles, Y.; Mougenot, J.; Gaspérini, M.; De Temmerman, G.
• Is Part Of: Nuclear materials and energy. Volume 19(2019)
• Page Start: 42
• Page End: 46
• Publication Date: 2019-05
• Subjects: Hydrogen -- Kinetic trapping -- Modelling -- Finite elements -- Abaqus -- User subroutine -- Macroscopic Rate Equations; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2019.01.023
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: A Generalized Oriani's Approximation (GOA) is proposed to take into account the transient trapping of hydrogen in Macroscopic Rate Equation models. The GOA ensures a correct convergence in finite element codes and is implemented in 3DS Abaqus code. Direct confrontations with classical McNabb and Foster MRE codes are performed to valid GOA and its implantation for a large set of diffusion/trapping material parameters. An experimental TDS spectrum is reproduced which shows the capability to take into account multi-trapping and the thermal loading of GOA. Simulations are performed for 2D thermally active structure of the diagnostics first wall of ITER tokamak. Abstract: In order to simulate hydrogen charging and discharging cycles of mechanically loaded structures full 3D Macroscopic Rate Equation (MRE) modelling is proposed based on a finite element method (FEM). The model, implemented in the 3DS Abaqus software, uses a generalized transport equation, which accounts for mechanical fields, hydrogen transport and trapping, and their evolution with time. The influence of a-priori known thermal field has also been included. To ensure the solution convergence and the numerical stability, the trapping kinetic is introduced by using an approximation of the analytical solution the McNabb and Foster equation. Comparisons with a relevant 1D MRE code and with thermal programmed desorption (TPD) experimental results are performed on a 1D configuration to validate the model. Next, the model is used to simulate the tritium diffusion and trapping in a 2D geometry of interest in the upper plug of ITER tokamak, and results of tritium inventory are compared with an equivalent 1D calculation.