Surface modification of alloys to reduce Hydrogen permeability in fusion alloys

It is imperative to reduce the loss of Tritium to provide safe and sustainable fusion energy. Hence, preventing accumulation and permeation of Tritium in reactor walls is critical. The purpose of this project is to understand Hydrogen (H), Deuterium (D) and Tritium (T) permeation in current fusion alloys and the influence of microstructural features/surface modifications to provide as barrier. It is

well known that different alloys and metals have drastically different permeabilities and while these are quite high for Austenitic steels and Tungsten, the materials themselves also need to serve as structural materials while withstanding radiation damage at high temperatures. While several options of barrier coatings have been considered for reduced activation steels and tungsten, the

influence of complex interfaces and near surface modifications has not been investigated on an atomic scale. The project plans to explore and perform surface modification of Eurofer and Tungsten using traditional and advanced methods and subsequent heat treatment to tailor material features (e.g. defects, grain boundaries and precipitates) in the first 10 -30 microns of these materials. Techniques

like Thermal Desorption Spectroscopy (TDS), Nano-SIMS and Nuclear Reaction Analysis (NRA) and Heavy Ion Elastic Recoil Detection Analysis (HE-ERDA) will also be used to deduce the binding energies of various material features and to quantify the depth profile of H/D/T. In-situ TEM in hydrogen atmosphere will also be used to understand at atomic level, interaction of H with tailored

material features. The experiment will utilise the UKAEA's Hydrogen-3 Advanced Technology (H3AT) infrastructure to expose materials samples to hydrogen isotopes using DELPHI (Device for Exposure to Low-energy Plasma of Hydrogen Isotopes). Primarily H and D will be used as a substitute for T, however the

UKAEAs TDS and DELPHI systems are tritium compatible