A Representative Volume Element Model for Investigating the Hydride Inclusion Effect on Ductility of Zry-Based Nuclear Fuel Cladding

Zirconium-based cladding degradation results from various factors during in-reactor operation, such as temperature change, irradiation, and hydrogen uptake. Hydride formation is the most crucial one, causing mechanical changes and negatively affecting cladding material ductility. Therefore, studying the effects of hydride formation on cladding ductility is important for maintaining nuclear fuel integrity. This paper proposes a representative volume element (RVE)-based modeling approach to explore the relationship between hydride inclusion parameters and cladding ductility. The RVE model incorporating Zircaloy-4 matrix and hydride fibers was created from a Python script by specifying the model parameters including RVE size/fiber size ratio, volume fraction, distribution, and orientation of the fibers. The material properties were optimized according to experimental data from uniaxial tensile tests. The model reasonably predicted cladding ductility, and the results agreed well with the reference experimental data. The evaluation results showed the promising applicability of the proposed RVE model to incorporate different hydride fiber characteristics.