Non-Destructive Characterization of Ion Irradiated Yttrium Hydride for Microreactor Applications

As energy demands increase, nuclear reactors, especially microreactors, become a promising energy source. These reactors run at high temperatures (>280°C), requiring moderators that can endure these environments. Yttrium hydride is a possible moderator, but little is known about the material’s phase stability and hydrogen retention under irradiation. Through the use of a gold ion beam, samples with stoichiometries ranging from 1.6 to 2.0 were irradiated and tested. Through Vickers hardness testing, a model was created showing a correlation between hydrogen content and hardness. Raman spectroscopy showed high temperature and irradiated samples have significant hydrogen loss. XRD quantified this hydrogen loss and showed that YH1.8 may retain hydrogen under irradiation. Nanoindentation supported this and proved that mechanical testing methods can help determine hydrogen content in yttrium hydride. Through these methods, yttrium hydride’s hydrogen retention and phase stability can be better understood and its use in a microreactor can be determined.