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Abstract

The design of structural steels for the construction of the regenerating casing of the future demonstration fusion reactor (DEMO) is in accordance with thermo-mechanical and neutron activation criteria. One additional basic aspect to be borne in mind in the manufacture and choice of the best structural steel to be used in DEMO are hydrogen isotopes (protium, deuterium and tritium) transportation properties through the surface and within the said material. Transportation properties under a diffusive system (diffusivity, solubility, permeability) and a surface system (consisting of absorption and recombination) together with trapping parameters (density of traps and trapping energy) are the variables which control important aspects of the reactor with regard to safety, fuel economy and plasma stability, such as the permeation of tritium through the casing, the inventory of tritium retained in the structural material and the recycling of deuterium and tritium to plasma.

Two techniques based on the build-up of gas, method of permeation and isovolumetric desorption have been traditionally used in the JRC-Ispra to assess the afore-mentioned hydrogen transportation properties in materials used in fusion. In this work a check of hydrogen transportation parameters obtained for the structural steel in question - 316L, MANET, F 2H and Batman - is made, together with the parameters recently assessed for OPTIFER-IVb martensitic steel, a promising candidate for making the structure of the reactor casing. Superficial oxidation of the steel as a restricting effect on the transportation of hydrogen in the material, as well as the influence of the microstructural configuration of the steel and the isotopic effect on transportation parameters are discussed.

Additional information

Authors: ESTEVAN GUSTAVO A, JRC EI, RE (IT);PERUJO A, JRC EI, RE (IT);LEGARDA F, UPV/EHU, E.T.S.I.I.T BILBAO;SEDANO LUIS A, UPV/EHU, E.T.S.I.I.T BILBAO
Bibliographic Reference: Oral Report delivered at: XXVI Reunion Annual De La Sociedad Nuclear Espanola, Hosted at: SNE, Leon (FR) 4-6 October 2000
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