Density Measurement of Irradiated and Nonirradiated Zirconium Oxide by Ptychographic X‐Ray Computed Tomography (PXCT)

This study establishes a fundamental groundwork for understanding the mass density of zirconium oxide formed on Zircaloy‐4 nuclear fuel cladding under in‐reactor and autoclave oxidation conditions, providing reference data for future applications. Ptychographic X‐ray computed tomography (PXCT) is employed to investigate the mass density of zirconium oxide samples. Pillar‐shaped specimens are produced from zirconium oxide layers grown in a pressurized water reactor (PWR) and an autoclave environment. A novel sample preparation protocol enables PXCT measurements of irradiated oxide. Electron density profiles are mapped along the oxide thickness with a spatial resolution of approximately 80 nm. The derived average bulk mass densities are equal to 5.11 ± 0.80 and 5.10 ± 0.97 g cm −3 for the irradiated and autoclaved oxides, respectively. Additionally, micro‐X‐ray diffraction (µXRD) mapping of the irradiated oxide sample confirms the dominance of the monoclinic (m‐ZrO 2 ) phase.