Abstract The structural strength of fuel assemblies in the nuclear reactor core during the energy generation process is an important characteristic to consider, due to the need to withstand lateral static and dynamic loads resulting from external forces, an outcome from postulated accidents, such as an earthquake. This requirement demands a sustained cooling activity for the fuel assembly by keeping a proper geometry, i.e., avoiding structure deformation. This can be achieved mainly by an adequate mechanical design for the spacer grids since this component would be the first to get in contact with the ordered mechanical structure (neighboring fuel assembly or the core baffle). In this way, the understanding of nuclear fuel mechanical behavior becomes essential, even to any subsequent geometrical modifications to optimize the performance of the fuel assembly. The main goal of the present study was to analyze the structural strength behavior of this component in order to provide consistent predictions of 16x16-type fuel assembly lateral stiffness when submitted to external forces. Thus, a beam-based finite element model was proposed to predict this fuel behavior, in which the hold-down spring force, spacer grid to guide thimble connection stiffness, and spacer grid stiffness were varied, in order to get more information about the fuel assembly rigidity sensitivity and verify if the proposed strengthening mechanisms for the structure are effective. Rigidity predictions of nuclear fuels allow verification of adequate design regarding functionality and reliability. Finally, the proposed finite element model was validated in terms of fuel assembly deflection by comparison with experimental results.

中文翻译：

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梁式有限元通过强化机制评价16×16燃料组件横向刚度的有效性

摘要 能量产生过程中核反应堆堆芯中燃料组件的结构强度是一个需要考虑的重要特性，因为需要承受外力产生的横向静态和动态载荷，假设事故（如地震）的结果。 . 这一要求要求通过保持适当的几何形状，即避免结构变形，对燃料组件进行持续的冷却活动。这主要可以通过对间隔网格进行适当的机械设计来实现，因为该组件将首先与有序的机械结构（相邻的燃料组件或堆芯挡板）接触。这样，对核燃料机械行为的理解就变得必不可少，甚至是为了优化燃料组件的性能而进行的任何后续几何修改。本研究的主要目标是分析该部件的结构强度行为，以便在受到外力时提供对 16x16 型燃料组件横向刚度的一致预测。因此，提出了一种基于梁的有限元模型来预测这种燃料行为，其中压紧弹簧力、引导套管连接刚度的间隔网格和间隔网格刚度是变化的，以获得有关燃料的更多信息。装配刚度敏感性并验证建议的结构加固机制是否有效。核燃料的刚性预测允许验证有关功能和可靠性的适当设计。最后，