Experimental verification of the classical theoretic isotope ratio of protium and deuterium permeability in Eurofer-97 and AISI 316 steels

The isotope effect of hydrogen transport parameters has been a well-studied phenomenon over the years, particularly interesting for the experimental characterisation of fusion materials by means of the protium-based tests. The veracity of the classical value has often been questioned, although no further consensus has been reached. However, this theoretical development is based on some ideal conditions that are not really checked during experimental tests, which may be precisely one of the main reasons for so much inconsistency with it. Based on this hypothesis, an experimental study of protium and deuterium permeability has been carried out with two samples, Eurofer-97 and AISI 316, taking care of the quality of the signal, the regime of the process, as well as the stability of the sample, in order to try to reduce as much as possible any cause of error or uncertainty. The study has been focused only on permeabilities, as it is the most reliable parameter for the experimental procedure used. The results have been clear, since when all these factors are ensured, the isotope ratio is surprisingly close to the expected root-of-two value, with errors of <5 %, and it also remains constant with temperature. Moreover, it has been shown that not taking these factors into account, messes up the results and increases the error, giving rise to possible misleading trends and conclusions.