Contribution to the structural analysis of cylindrical fuel rods of nuclear reactors with consideration of multidimensional behaviour, based on finite-element-method

A critical review of the state-of-the-art in fuel rod structural analysis shows, that in general analyses are based on one-dimensional models. Complementary this investigation considers the two-dimensional aspects of the fuel rod design. Therefore the FEM-codes: ZIDRIG and FINEL have been developed, which show the following features: - two-dimensional in r-phi or r-z-plane - materials nonlinearities (e.g. creep, plasticity) - geometrical nonlinearities (large deflections) - time dependent behaviour (e.g. creep, time dependent externel loads) For the cladding the influences of manufacturing tolerances, integral ribs and end-plugs as well as the behaviour during LOCA (ballooning) have been calculated. The pellets have been analysed with their real dimensions and with consideration of plasticity and cracks. Finally the mechanical pellet-cladding-interaction is considered, i.e. bamboo like deformation. (orig.)