Abstract The lead-based fast reactor is very attractive as one of the Generation-IV nuclear energy systems due to high-power density, heavy liquid metal coolants with a high boiling point as well as harmless interaction with air or water. Nuclear heat is generated from very high neutron flux that is regulated and controlled by the drop of the Control Rods (CRs) for safe operation. The resisting effect of the Lead Bismuth Eutectic (LBE) due to high density on the driving force of the CR Assembly (CRA) during the fall is crucial, which some delays may lead to unavoidable accidents. The mathematical approach has been applied to investigate the CRA dynamics of lead-based research reactor. The non-linear differential equations governing the motion of the CRA as well as the LBE flow have been ascertained to capture the pertinent parameters. Using the Fourth-Order Runge-Kutta iteration method, a computer program was developed with MATLAB and it can be used to calculate the drop time of the CRA and other important parameters described and presented in the study. Compared with the results of the experiment in the available literature, the program developed was proved to be applicable and reliable. The results showed that among the LBE flow characteristics, the density is the most influential parameter on the drop time and tends to have a positive relationship with the drop time. The total CRA mass contributes to the driving force of the CRA to reduce drop time when increased. Finally, the result of the theoretical model will serve as a basis to analyse the auxiliary mechanism and thus, help make informed choice on LBE flow parameters during modification to improve safety.

中文翻译：

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LBE冷却研究堆控制棒组件下落动力学分析

摘要 铅基快堆作为第四代核能系统之一，具有高功率密度、高沸点的重金属液态冷却剂以及与空气或水的无害相互作用等优点，因此非常具有吸引力。核热是由非常高的中子通量产生的，该通量由控制棒 (CR) 的下降调节和控制，以确保安全运行。铅铋共晶 (LBE) 由于高密度对 CR 组件 (CRA) 坠落过程中的驱动力的抵抗作用至关重要，一些延误可能会导致不可避免的事故。数学方法已被应用于研究铅基研究堆的 CRA 动力学。控制 CRA 运动和 LBE 流的非线性微分方程已被确定以捕获相关参数。使用四阶 Runge-Kutta 迭代方法，用 MATLAB 开发了一个计算机程序，它可以用来计算 CRA 的下降时间和研究中描述和呈现的其他重要参数。与现有文献中的实验结果相比，证明了所开发的程序是适用的和可靠的。结果表明，在 LBE 流动特性中，密度是对下落时间影响最大​​的参数，并且往往与下落时间呈正相关。总 CRA 质量有助于 CRA 的驱动力，以在增加时减少下降时间。最后，理论模型的结果将作为分析辅助机制的基础，从而有助于在修改过程中对 LBE 流动参数做出明智的选择，以提高安全性。