Application of the Al2O3–Zr material system in simulating UO2–Zr fuel rod melting behavior

Understanding the melting behavior of nuclear fuel rods is crucial for ensuring reactor safety. This study investigates the potential of the Al2O3–Zr material system, which is similar to that of UO2–Zr, to serve as a substitute for fuel rods in simulating their melting behavior. The research employed the FROMA device, a high-temperature melting apparatus, to conduct experiments on Al2O3 and Zr materials. The samples were subsequently analyzed using SEM, EDS, and XRD techniques. The experimental observations and post-processing analysis revealed several key findings. First, molten materials migrated downward along the outer wall of the cladding, exhibiting a region with violent reactions and spattering. This migration pattern displayed characteristics of both thin film and rivulet flow, indicating the influence of surface tension and gravitational forces. Second, element diffusion played a crucial role in the reaction between Al2O3 and Zr, leading to the formation of a layered structure within the cladding. This structure, characterized by layers of Al2O3, Zr oxide, and Al–Zr alloys, closely resembled the composition of UO2–Zr fuel rods. Finally, the microstructural analysis revealed the presence of various Al–Zr alloys and ZrO2 compounds, highlighting the complex interplay between the two materials during the melting process. The findings of this study demonstrate the feasibility of using the Al2O3–Zr material system as a substitute for UO2–Zr fuel rods in simulating their melting behavior. The similarities in the observed phenomena and microstructure provide valuable insights into the fundamental mechanisms governing the melting of nuclear fuel rods. This research contributes to a better understanding of the melting behavior of nuclear fuel rods and offers a practical alternative for further investigation. The findings have implications for the development and validation of numerical analysis programs, as well as for the design and safety assessment of nuclear reactors.