Deuterium permeability of the austenitic stainless steel AISI 316

The permeability in membranes of stainless steel AISI 316 was determined at different membrane temperatures and upstream deuterium driving pressures. The results are in good agreement with others reported in the literature. Measurements were also performed with membranes having an upstream surface covered with a layer of the liquid Pb-17Li alloy, to represent the Pb-17Li/steel interface of a cooling tube in the blanket of a fusion reactor. In this case, the values for the permeability decreased by a factor of 1 to 4 with respect to the absence of Pb-17Li, and also the activation energy of the permeation decreased from 52000 to 34000 J/mol. This means that the solubility of deuterium in Pb-17Li is lower than in AISI 316 and nearly independent of temperature, acting therefore as a permeation barrier for deuterium. Also the values of the diffusivities have decreased by a factor of about 2 with respect to those obtained in absence of Pb-17Li. Since the diffusivities have been derived from the same type of deuterium flux measurements than the permeabilities, it was concluded that the Pb-17Li had acted as a diffusion barrier. (orig.)