RIPER: An irradiation facility to test Radiation Induced Permeation and release of deuterium for fusion blanket materials

An efficient reduction of gaseous hydrogen isotope permeation through a metal wall is essential in several applications for the tritium inventory control of fusion energy devices. Tritium is also a safety and biological hazard and tritium losses by permeation through the materials is a critical point to be avoided to ensure safety in fusion energy. Ceramic coatings are candidates to reduce tritium permeation, into the breeder blankets of future devices, due to its low hydrogen permeation rate, excellent corrosion resistance and good mechanical properties. Furthermore, these functional materials of future fusion reactors are expected to be subjected to elevated temperature and high level of radiation fluxes and their impact on the tritium inventory has not been properly assessed mainly due to the lack of data available in the literature on this effect. Radiation induced changes in the composition and microstructure of the materials may alter tritium control in future devices. In this context, a new permeation facility “Radiation Induced Permeation” (RIPER)has been developed at CIEMAT in order to obtain relevant data on permeation of hydrogen isotopes in structural/functional materials under irradiation. This system allows one to differentiate and characterize gas concentration driven permeation, and permeation due to different parameters applied to the sample conditions like temperature, irradiation dose or electric field. The reliability of the system has been checked by means of permeation measurements for different materials in comparison with values found in literature and different measurements during irradiation have been performed. The experimental challenges of these types of measurements are reflected in this paper.