NSUF 25-5487: Evaluating the role of FeCrAl Alloy as a Hydrogen Permeation Barrier in Irradiated Yttrium Hydrides through In-Situ Synchrotron X-Ray Diffraction Studies
Factory-fabricated and truck-transportable nuclear microreactors rely on solid-state moderators to reduce reactor footprint while maintaining performance under extreme temperature and space-constrained environments. Among candidate materials, sub-stoichiometric yttrium hydride (YHx) is highly attractive due to its high hydrogen number density, thermal stability and mechanical integrity. Given all advantageous properties, the yttrium hydrides are susceptible to hydrogen redistribution and loss under fast-neutron irradiation, compromising moderation efficiency and reactor safety margins. A promising mitigation strategy is to envelop YHx moderators with barrier coatings, such as FeCrAl alloys, that is known to suppress hydrogen permeation. However, the coupled behavior of FeCrAl and irradiated YHx under reactor-relevant thermal conditions remains unexplored. This project addresses that knowledge gap through a multimodal investigation combining in-situ synchrotron X-ray diffraction and transmission electron microscopy studies. YHx disks, neutron irradiated at the High Flux Isotope Reactor (HFIR) facility at Oak Ridge National Laboratory (ORNL), will be paired with oxidized or non-oxidized FeCrAl plates to make distinct YHx–FeCrAl assemblies. The selected YHx disks have identical stoichiometry and irradiation dose, but differ in irradiation temperature. Synchrotron XRD experiments, under controlled thermal cycling, will track crystallographic evolution, hydrogen desorption kinetics and irradiation-induced damage recovery. On the other hand, complementary TEM characterizations of pre-annealed and post-heating alloy specimens will resolve barrier microstructure and hydrogen-induced features at the YHx–FeCrAl interface. This experimental design systematically isolates the effect of irradiation temperature and barrier oxidation, providing fundamental understanding of the influence of FeCrAl on hydrogen retention in irradiated hydrides. The anticipated scientific outcome will be the first mechanistic framework for temperature-driven hydrogen transport in irradiated YHx coupled with engineered permeation barriers. If successful, this work will significantly advance the state-of-knowledge on hydride moderators and inform design strategies for microreactor deployment. The novel study is expected to be published in a high-impact journal.
Additional Info
| Field | Value |
|---|---|
| Awarded Institution | Oak Ridge National Laboratory |
| DOI | 10.46936/NSUF/60015714 |
| Embargo End Date | 2028-01-22 |
| Facility Tech Lead | Kory Linton, Simerjeet Gill |
| NSUF Call | FY 2025 Super RTE Call |
| PI | Shaileyee Bhattacharya |
| PIE Facilities | Low Activation Materials Design and Analysis Laboratory, National Synchrotron Light Source II |
| Prep Facilities | Low Activation Materials Design and Analysis Laboratory |
| Project Member | Professor David Sprouster, Assistant Research Professor - Stony Brook University (https://orcid.org/0000-0002-2689-0721) |
| Project Member | Dr. Caleb Massey, R&D Staff Member - Oak Ridge National Laboratory (https://orcid.org/0000-0003-1093-3958) |
| Project Member | Dr. Matthew deJong, Postdoctoral Research Associate - Oak Ridge National Laboratory (https://orcid.org/0000-0003-1281-9825) |
| Project Member | Dr. Shaileyee Bhattacharya, Postdoctoral Research Associate - Oak Ridge National Laboratory (https://orcid.org/0000-0001-5711-7443) |
| Project Type | RTE |