NSUF 26-5622: Post-Irradiation Examination of MITR-Irradiated Advanced Moderator Module (AMM) Capsules: Multilayer Barrier Integrity, Hydrogen Retention, and Microstructural Evolution
This project will perform post-irradiation examination (PIE) of a MITR-irradiated Advanced Moderator Module (AMM) developed under the DOE-NE Microreactor Program to validate hermetic containment of yttrium hydride (YH₂−x) for high-temperature neutron moderation. The primary objectives are to (i) assess overall AMM containment integrity after irradiation, (ii) recover the irradiated YH₂−x pellet by controlled disassembly and independently characterize the H₂ permeation-barrier coating/Nb liner, Nb weld seals, and outer SiC composite shell, (iii) quantify irradiation-driven microstructural and chemical evolution at critical interfaces that could enable hydrogen loss or degradation, and (iv) measure irradiation-induced changes in thermal transport behavior of the coating/liner system.
Methods will include shielded sample preparation (sectioning/opening and cross-section preparation), SEM (imaging, EDS mapping, EBSD where applicable) for microstructural screening, site-specific FIB liftouts from coating/Nb/SiC/weld regions, high-resolution TEM/STEM with EDS/EELS for nanoscale defect and interfacial reaction-layer characterization, powder XRD of the recovered pellet to assess hydride phase stability and stoichiometry trends, and thermophysical measurements via laser flash analysis (and/or thermal conductivity microscopy depending on specimen geometry).
If successful, the work will provide the first direct irradiation-performance dataset linking hydrogen retention, barrier-coating integrity, and interfacial stability in an integrated microreactor moderator containment architecture (YH₂−x/Nb + barrier/SiC). This will significantly advance the state-of-the-knowledge by identifying irradiation-induced degradation modes (e.g., cracking, delamination, diffusion-assisted reaction layers, hydride phase changes) and establishing microstructural acceptance criteria for long-duration operations.
The anticipated scientific outcomes include quantitative evidence of hydride phase stability, nanoscale characterization of coating and weld performance under irradiation, and validated thermal-transport property changes, together enabling informed design optimization and down-selection of moderator containment strategies for deployable high-temperature microreactors.
Additional Info
| Field | Value |
|---|---|
| Awarded Institution | Argonne National Laboratory |
| DOI | 10.46936/NSUF/60017670 |
| Embargo End Date | 2028-04-22 |
| Facility Tech Lead | Noé Morales |
| NSUF Call | FY 2026 RTE 1st Call |
| PI | Sumit Bhattacharya |
| PIE Facilities | Irradiated Materials Characterization Laboratory |
| Prep Facilities | Irradiated Materials Characterization Laboratory |
| Project Member | Dr. Yinbin Miao, Principal Materials Scientist - Argonne National Laboratory (https://orcid.org/0000-0002-3128-4275) |
| Project Member | Dr. Sumit Bhattacharya, Principle Material Scientist - Argonne National Laboratory (https://orcid.org/0000-0002-6251-6075) |
| Project Type | RTE |