Influence of interface conditions on hydrogen transport studies

Abstract

This work investigates the influence of hydrogen chemical potential continuity across solid material interfaces. The implementation of the mathematical model in FESTIM is verified using the Method of Exact Solutions (MES) and the Method of Manufactured Solutions (MMS) in 1D, 2D, with complex material properties and inhomogeneous temperature fields. A comparison test between FESTIM, TMAP7 and Abaqus codes is also performed and the codes show good agreement. The chemical potential continuity condition has an impact up to 40% on the outgassing particle flux on 4 mm composite slabs (W/Cu and Cu/EUROFER) compared to mobile concentration continuity. A method for rapid identification of materials properties from outgassing flux measurements is given. The influence of chemical potential conservation on monoblock inventory is then studied. It is shown that, for the 1D and 2D ITER divertor monobolocks cases, discrepancies only start to appear after approximately 5 × 10 6 s of full power.

Modelling of hydrogen isotopes trapping, diffusion and permeation in divertor monoblocks under ITER-like conditions

“…2D retention fields Figure 7 shows the deuterium retention in the half-monoblock after 10,000 seconds of plasma exposure for scenario I (a) and II (b). As already mentioned in [10,11,12], and as observed in the 1D depth profiles (figure 3), the presence of the thermal gradient implies that the maximum of D concentration is not at the exposed surface but near the cooling pipe. This is especially visible for scenario I (hottest scenario) for which the maximum of retention tends to follow the shape of the cooling pipes.…”

“…The continuity of the chemical potential chosen here leads to a discontinuity of the concentration of mobile particles at the W/Cu and Cu/CuCrZr interfaces. Especially, as shown in [12], this tends to enhance the retention in the CuCrZr part.…”

“…The transport and trapping parameters for Cu and CuCrZr used for these simulations are the same as the one given in [11]. At material interfaces, the conservation of the chemical potential is guaranteed with the model described in [12]. This interface model required the solubility of HIs in the different materials taken from this same reference.…”

Fuel retention in WEST and ITER divertors based on FESTIM monoblock simulations

“…Numerical modelling of H transport and retention in and outgassing from plasma facing components [4, 5,6,7] is therefore often required in order to tackle both issues. These simulations are supported by experimental work to determine key properties of fusion materials.…”

Numerical simulation of the transient hydrogen trapping process using an analytical approximation of the McNabb and Foster equation. Part 2: Domain of validity

“…In the frame of hydrogen-material interactions, such a scheme has been proposed to solve the McNabb & Foster trapping equation [23] and to provide Abaqus these extra needed functions [1]. This scheme (named thereafter "Generalized Oriani's Approximation" or GOA) has been successfully compared to results obtained from experiments or computations [1] and successfully applied to several configurations in terms of geometries, mechanical behaviors and boundary conditions [34][35][36][37][38][39][40].…”