Numerical Simulation of Thermo-Hydraulic Characteristics of 7-Pin SFR Test Fuel Bundle With Variable-Pitch Helical Wire

Abstract

Abstract This paper is focused on the applicability of variable-pitch helical wire in a 7-pin SFR test fuel bundle by using CFD method. The differences between the variable-pitch helical wire scheme and the even-pitch helical wire scheme in the pressure loss, velocity, temperature field of the test fuel bundle are compared and analyzed. The simulation results show that it is reliable to carry out the thermo-hydraulic analysis of SFR test fuel bundle by using CFD numerical simulation method. The helical wire mixing ability to the coolant and the pressure drop is influenced by the helical wire pitch. Compared with the even-pitch helical wire scheme on fuel rod surface, the variable-pitch helical wire doesn’t drastically change the flow field structure while the pitch changes, but gradually increases its mixing ability to the coolant along the axial direction, which is more conducive to accelerating balance the thermal inhomogeneity and inhomogeneity ratio of the coolant, solve the problem of temperature rise caused by the coolant congestion on the contact structure between the helical wire and fuel rod surface. The stronger the mixing ability of the helical wire to the coolant, the more effective it is to lower the maximum temperature of the coolant. The application of the variable-pitch helical wire can well match the demand of the coolant for thermal and hydraulic needs, and the safety and economy of the assembly can be correspondingly improved.