Performance analysis of U-50Zr helical cruciform fuel during loss-of-coolant accidents Based on MOOSE framework

Abstract

Helical Cruciform Fuel (HCF) embodies advancement in the fusion of unique geometric design with state-of-the-art metallic alloy materials. This innovative design leverages the optimized heat transfer characteristics of its distinctive geometry to potentially achieve elevated power output levels. Additionally, the employment of U-50Zr fuel contributes significantly to reducing the risk of potential accidents. The operation of nuclear fuel is a typical multi physics process, and accurate evaluation and prediction require advanced research methods. The open-source, parallel finite element framework MOOSE, a renowned software platform, is integral to the effective modeling and simulation of these intricate processes. Based on the MOOSE framework, simulate the operational behavior of HCF under high burnup conditions in pressurized water reactor environment and challenging scenarios of loss of coolant accident (LOCA). The calculation results indicate that U-10Zr experiences excessive swelling during the initial burnup period, and stress will concentrate at the concave arc position of the cladding. The swelling of U-50Zr gradually increases with stress, rendering it a more suitable alternative fuel for HCF. During LOCA accidents, the mechanical behavior of the fuel assembly, particularly the cladding, undergoes a sharp decrease in stress after an increase.

Notably, the minimum axial stress post-cladding stress drop occurs near the central height. Furthermore, the two axial helices of the concave and convex arcs of the cladding exhibit opposing characteristics during such accidents. A comparative analysis between LB-LOCA and SB-LOCA reveals a significant lag in the reduction of cladding stress in the case of SB-LOCA.