U-50Zr helical cruciform fuel performance analysis based on MOOSE framework.

• A MOOSE-based application for the HCF under normal conditions and RIA is developed and verified. • Couple radiation-thermal-mechanics physics modules and focus on heat conduction, coolant convection heat transfer, thermal expansion, solid swelling, gaseous swelling, irradiation growth, and creep of the HCF. • The distribution of the HCF stress and temperature under normal operating conditions is investigated, and corresponding improvement measures are put forward. • The stress and temperature distribution of the HCF and the mechanical behavior of the cladding under RIA are investigated, and proposals for accident-tolerant design are put forward. Helical Cruciform Fuel (HCF) represents a groundbreaking innovation that merges unique geometric structure with advanced metallic alloy materials. Due to the heat transfer optimization resulting from its distinctive geometric structure, HCF demonstrates the potential to achieve higher power output. Moreover, the utilization of U-Zr metal fuel in HCF contributes to enhancing the accident tolerance of the fuel system. Fuel performance analysis encompasses a series of intricate physical processes. To effectively model and simulate the 3D multi-physics coupling of these processes, advanced computational tool and software platform MOOSE framework is essential. In this work, thermo-mechanical capability for analysis of HCF was conducted in MOOSE-based fuel performance code PHOENIX. The operation of high burnup HCF behavior and reactivity-initiated accident (RIA) conditions are simulated. As the irradiation and burnup processes persist, the distribution of stress within the fuel tends towards a state of uniformity, with the stress concentration within the cladding occurring predominantly at the concave arc position. During RIA, the central height position of fuel stress exhibits a sharp increase and significant stress drop at the concave arc position of cladding, rendering it incapable of supporting the fuel. Furthermore, the cladding at various heights exhibits distinct mechanical behaviors, which can be categorized into three regions: a region relatively unaffected by the accident, a transition region, and a plastic deformation region. [ABSTRACT FROM AUTHOR]