The Grid Strap Vibration Characteristics of the 5×5 Nuclear Fuel Mock-up

Abstract

Since the fuel is always exposed to turbulent flow, the grid strap shows flow induced vibration characteristics that impact on the nuclear fuel soundness. The dynamic behavior of grids in nuclear fuels is quite complex, since two pairs of spring and dimple support are contacted with rods by friction in the limited space. This paper focuses on investigation of the grid strap(test fuel strap, TFS) vibration in one cell. TFS consists of a single spring and double dimples. To identify the grid strap vibration, modal analysis of the strap is performed using finite element method(FEM). Modal testing on a 5×5 grid structure without rods is performed. The modal testing results are compared to analytic results. In addition, random test considering rod effect is performed about a 5×5 grid with rods under real contact condition in the air. Finally, the strap vibration of a 5×5 fuel bundle in inves-