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