Study on single-phase flow and irradiation mechanics multi-physics field coupling properties of three-petal fuel rod

As a new type of fuel assembly, the thermo-hydraulic and mechanical properties of petal-shaped fuel rod are directly related to the safe operation of the reactor. In this study, the multi-physics field coupled model for coolant single-phase flow heat transfer, and mechanical properties of three-petal fuel rod is established through ABAQUS-STAR CCM+, realizing real-time data interaction between different computational domains. The results show that the transverse flow of coolant affects the temperature field distribution, and the multi-physics field coupling is closer to the real situation of convective heat transfer of fuel rods. Under the irradiation swelling, the maximum Mises stress moved from the inner concave arc to the outer convex arc, and increased to 433.23 MPa at the burnup of 8.22 % fissions of initial mental atoms (FIMA). In addition, the properties of the fuel rod at different inlet flow velocities are analyzed. When the burnup reaches 3.31 % FIMA at 2.5 m/s inlet flow velocity, it enters the plastic stage earlier. The effect of different coupling modes on displacement deformation is also discussed, which shows that it is feasible to ignore the influence of displacement deformation of the fuel rod on coolant.