Insights into the uranium-H2O corrosion mechanism from the atomic-scale coexistence relationship between UH3 and UO2

This study investigates the corrosion products formed on the surface of metallic uranium (U) during H2O corrosion in an open to air system. The results unambiguously reveal the presence of UH3 nanoparticles dispersed in the non-adherent corrosion layers, albeit in small quantities. High-resolution transmission electron microscopy provides an atomic-scale depiction of the coexistent structure of UH3 and UO2, which is described by an innovative “Core (UH3) – Shell (UO2)” model within the corrosion layers. The direct observation of UH3 in this form provides evidence supporting the U-H2O corrosion mechanism postulated to be catalyzed by the interfacial hydrides.