The Effect of Spacer Grids on the Formation of Added Mass under the Bending Vibrations of a Fuel-Element Bundle in a Covered Fuel-Element Assembly of a VVER-440 Reactor

Abstract

A significant effect of spacer gratings exerted on the dynamic characteristics of the covered fuel-element assemblies is shown. The calculated and experimental values of the added mass in the course of the bending vibrations of a bundle of fuel elements (fuel elements) are in good agreement between each other only when taking into account the flow of liquid in a narrow gap between the hexahedral surface of the spacer gratings and the hexahedral border of the cover of fuel-element assemblies. The small dimensions inherent in the spacer gratings in the axial direction of fuel-element assemblies lead to uneven distribution of the added mass along the length of the fuel-element assemblies, which is a significant factor in the study of bending oscillations of a bundle of fuel elements in liquid.