Modelling and modal properties of nuclear fuel assembly

The paper deals with the modelling and modal analysis of the hexagonal type nuclear fuel assembly. This very \ncomplicated mechanical system is created from the many beam type components shaped into spacer grids. The \ncyclic and central symmetry of the fuel rod package and load-bearing skeleton is advantageous for the fuel assembly \ndecomposition into six identical revolved fuel rod segments, centre tube and skeleton linked by several \nspacer grids in horizontal planes. The derived mathematical model is used for the modal analysis of the Russian \nTVSA-T fuel assembly and validated in terms of experimentally determined natural frequencies, modes and static \ndeformations caused by lateral force and torsional couple of forces. The presented model is the first necessary step \nfor modelling of the nuclear fuel assembly vibration caused by different sources of excitation during the nuclear \nreactor VVER type operation.