Specific programme: EURATOM
UPV/EHU Partner Status: Linked Third Party with CIEMAT
UPV/EHU PI: Igor Peñalava
Project start: 07/02/2019
Project end:   06/02/2021

Brief description:

The characterization of H isotope transport parameters through containment (Eurofer/reduced activation ferritic-martensitic steels) and functional structures (e.g. tritium extraction systems) is a key factor for the safety and design concepts of fusion systems. In particular, surface rate constants which are essential for the numerical methods used for the tritium inventory control calculations, have not been properly determined for the reference structural material (Eurofer). The Thermoperm (Ciemat) and PERMRIG (UPV/EHU) facilities have been successfully employed in the past for D/H permeability measurements in Eurofer from ~ 350 to 550 ºC in a wide range of pressures.

For the present task, double-ckeck validation of dissociation and recombination coefficients will be carried out by using both installations. The measuring method is similar in the two facilities, the material of interest acting as a membrane which separates a high gas pressure region and a low-pressure region which initially presents vacuum conditions. Surface limited regime will be first established according to sample thickness and pressure range, and surface constants determined from the stationary flux under those conditions. The maximum difficulty relies on the achievement of low enough driving pressures, presumably in the order of 1-100 Pa. Direct permeation experiments have been carried out in PermRIG and Thermoperm at pressures above ~100 Pa and ~ 10 Pa respectively, lower pressures being achieved by inverse permeation (~1 Pa). Due to the higher difficulty in the mathematical analysis for inverse permeation and hence the increased error that it represents, direct permeation is preferred. Direct permeation measurements are projected from 10 to 100 Pa in Thermoperm facility, that represents an improvement when compared with the only available data for surface coefficients (direct permeation) in Eurofer which were obtained at higher pressures.