ICSI Contributions Regarding Barriers Against Hydrogen Isotope Permeation Through Stainless Steel and EUROFER97 in DEMO Applications

One of the essential requirements for the future fusion power plants is the tritium self-sufficiency. Still, during transport from the breeding blanket towards the extraction system, a fraction of tritium permeates through the piping and containment walls, and it might escape into the outer environment. To reduce the amount of permeated tritium in the coolant, the obvious solution is coating of the tritium exposed surfaces with anti-permeation barriers. Stainless steels and EUROFER97 are the main materials for DEMO systems construction. While EUROFER97 is a reduced activation martensitic steel specially designed for the construction of fusion reactor blankets which will be exposed to neutron irradiation, stainless steels like 316(L) are used for constructing the other components and systems. Hydrogen isotopes in various gas mixtures are permanently circulated through the reactor systems as they are the fuel which drive it. This paper is a detailed analysis of different technologies and materials conceived for creating efficient barriers against hydrogen permeation through stainless steel and EUROFER97. This literature review presents some investigation of important aspects regarding the development of stable hydrogen permeation barriers in order to prevent adsorption in structural materials and permeation of hydrogen isotopes. These barriers will help avoid the corrosion and embrittlement effects, and also, they will prevent the migration of tritium towards other systems and environment which poses radiation protection issues.