[en] The fresh fuel for Bushehr Nuclear Power Plant-1 is due to be transported inside special containers which are supposed to be designed to stand against vibrations and impacts in order to protect the fuel from any possible damage. In order to perform die structural dynamic analysis of the containers, while being subjected to impact of dynamic forces, it is necessary to perform the vibration analysis which will lead to the vibrational modes and their natural frequencies for the structure of the containers. The vibration opposition of the containers must be far beyond the critical resonance. The resonance frequencies about the natural frequency of the structure will cause the enhancement of the oscillation range and may be ended with its disintegration. Determination of the natural frequencies and their mode shapes can be achieved by vibration-analyzing-methods. The amount of the natural frequency of any structure depends strongly on its shape, material and its lean points, as well as the amount and the type of the loads which the structure will be subjected to. In the present research, the container of the fresh fuel of Bushehr Nuclear Power Plant-1 is simulated by ANSYS^R10.0 and their ten natural frequency modes have been calculated

[en] The spent fuel assemblies of Bushehr Nuclear Power Plant are planed to be transported by TK-13 casks. Each spent fuel transportation cask holds 12 spent spent fuel assemblies and has a thick steel container to provide shielding. The calculations have been performed for fuel assemblies with burn ups of 60 MWd/kg and a 3-years cooling period. The ANSYS10.0 general finite element analysis package was selected for this analysis, since it is an analytical tool, widely used for licensing of spent nuclear fuel casks. The selected model included all the significant heat transfer paths within the casks and between the casks and the external environment. The computational model was subjected to the thermal environment of the tunnel during the fire transient using boundary conditions derived from the results of the fire dynamics simulator computational fluid dynamics code. The model of cask constructed in ANSYS10.0 consists of a detailed 3-D representation of a symmetric half cross section of the spent fuel transportation cask and a complete cross section of the surrounding tunnel wall. In this model, the cask is oriented horizontally within the tunnel. This orientation gives the cask's outer surface the maximum exposure to the highest temperatures in the fire environment. This includes exposure from the tunnel surfaces by thermal radiation exchange and the flow of hot gases generated by the fire, which results in significant convection heat transfer to the package during the fire transient. The results of this evaluation strongly indicated that neither spent nuclear fuel particles nor fission products would be released from the spent fuel transportation cask. The internal temperature of TK-13 cask which was analyzed through the fire tunnel scenario did not reach the level that could result in rupturing of the fuel cladding