ANALYSIS OF FLOW-INDUCED VIBRATION OF WIRE-WRAPPED FUEL BUNDLE CONSIDERING THE EFFECTS OF GEOMETRICAL AND BOUNDARY CONDITIONS

For the wire-wrapped fuel assemblies in liquid metal reactors, high-speed scouring of the liquid metal coolant, and the lateral flow caused by the presence of wires lead to the vibration of fuel rods. And the vibration may induce micro-motion wear and damage the integrity of the cladding. In this paper, the flow-induced vibration problem of a 7-pin bundle assembly with filament winding positioned under axial flow of lead-bismuth alloy was analyzed by FSI numerical simulation method. Firstly, the vibration response of the wire-wrapped rod bundle with different pitch was calculated by changing the pitches of the winding wire. Then the vibration response of the wire-wrapped rod bundle with different pitch to diameter ratio was calculated by changing the pitch value. Finally, the vibration response of the wire-wrapped rod bundle with different inlet velocities was calculated by changing the inlet velocity. The analysis results show that the change of pitch of wire will affect the amplitude, vibration balance position and vibration frequency of the wire-wrapped fuel bundle; the change of pitch to diameter ratio will affect the vibration balance position, but not the amplitude and vibration frequency; the change of inlet velocity will affect the vibration balance position and vibration frequency, but not the amplitude.