Abstract Understanding the dynamic response of core structure in a fast reactor under earthquake could provide a guideline for the reactor design. A core consists hundreds of ducts; this fact challenges full-scale experiments or simulations. A popular solution is to use a matrix of 7 ducts to represent the whole core, yet the effect of boundary constraint on the experiment or simulation representation has not been reported so far. In this article, two types (type 1 and type 2 as in graphical abstract) of boundary constraint, as a bracketing limit to the real-world situation, has been investigated with a coupled acoustic-structural (CAS) model, and the effects of the gap size on the dynamics and the seismic response are explored. Results show that type 2 constraint exerts a stronger constraint than type 1 constraint does and synchronizes ducts with ground excitations. In addition, a smaller gap under type 1 boundary constraint reduces the eigenfrequencies and introduces stronger coupling effect between ducts.

中文翻译：

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浸入流体中的 7 六边形燃料管道动态响应的边界效应

摘要 了解地震作用下快堆堆芯结构的动力响应可为反应堆设计提供指导。一个核心由数百个管道组成；这一事实挑战了全面的实验或模拟。一种流行的解决方案是使用 7 个管道的矩阵来表示整个核心，但目前尚未报告边界约束对实验或模拟表示的影响。在本文中，两种类型（图形摘要中的类型 1 和类型 2）边界约束，作为对现实世界情况的包围限制，已经使用耦合声学结构 (CAS) 模型进行了研究，以及探讨了动力学和地震响应的间隙大小。结果表明，类型 2 约束施加比类型 1 约束更强的约束，并使管道与地面激励同步。此外，在类型 1 边界约束下较小的间隙会降低特征频率并在管道之间引入更强的耦合效应。