池式快堆泵支承热变形简化计算方法研究

Research on Simplified Method for Calculating Thermal Deformation of the Pump Support in the Sodium-Cooled Fast Reactor

摘要: 池式快堆主容器的热钠池上部空间内的主泵、中间热交换器(IHX)、独立热交换器(DHX)等设备的支承结构贯穿主容器的上封头，钠池中的钠液面上方覆盖有氩气。在反应堆正常运行工况下，高温液钠通过自然对流、热辐射等方式将热量传递给这些上部结构。为了评估这些结构的完备性，需要计算它们的温度分布及热变形。目前一般采用数值模拟方法获得这些结构的温度场和热变形，而传统数值模拟需要建立三维模型，这将耗费大量计算资源和计算时间，而且计算结果往往难于获得实验验证。因此，在工程设计上迫切需要建立起一套快速便捷且经过实验验证的热钠池上部结构的温度场分布及热变形的计算方法。本研究提出了一套池式快堆泵支承温度分布及热变形简化计算方法，采用局部二维建模计算替代详细三维建模计算，有助于降低网格数量，显著节约计算资源。首先通过与快堆上部空间换热特性缩比试验的比较验证了该方法的合理性，进而采用同样的方法对池式快堆上部空间流动传热行为进行建模与分析。计算结果表明氩气空间内存在较明显的自然循环流动，主泵支承颈在相同高度下靠近堆芯的一侧的温度高于远离堆芯的一侧温度，且远离堆芯一侧的温度在高度方向上下降的更快。最后将得到的主泵支承颈的温度场用于热变形计算，为池式快堆泵支承结构热变形优化设计提供重要数值参考。

Abstract: In the sodium-cooled fast reactor, the supporting structures of the main pump, intermediate heat exchanger (IHX), independent heat exchanger (DHX) and other equipment in the upper space of the sodium pool of the primary container penetrate the upper head of the primary container. The upper region above the sodium level is covered with argon. Under the normal operating conditions of the reactor, high-temperature liquid sodium transfers heat to these upper structures through nat-ural convection, thermal radiation, etc. In order to evaluate the completeness of these structures, their temperature distribution and thermal deformation need to be calculated. At present, numerical simulation methods are generally used to obtain the temperature field and thermal deformation of these structures. However, traditional numerical simulation requires the establishment of detailed three-dimensional models, which will consume a lot of computing resources and calculation duration, and the calculation results are usually difficult to obtain experimental verification. Therefore, there is an urgent need to establish a fast, convenient and experimentally verified calculation method for temperature field distribution and thermal deformation of the upper structures of the hot sodium pool. In this study, a simplified calculation method for temperature distribution and thermal deformation of the pump support in the Sodium-cooled fast reactor is proposed, and local 2D modeling calculation is used instead of detailed 3D modeling calculation, which helps to reduce the number of meshes and significantly save computing resources. Firstly, the legitimacy of the proposed method is verified by comparison with the scaled test of the heat transfer characteristics of the upper space in the fast reactor. Then, the same method was used to model and analyze the heat transfer behavior of the upper space in the large Sodium-cooled fast reactor. The calculation results show that there is an obvious natural circulating flow in the argon space, and the temperature of the main pump support neck near the core at the same height is higher than that of the side away from the core, and the temperature on the side away from the core drops faster in the height direction. Finally, the temperature field of the main pump support neck is used for the calculation of thermal deformation, which provides an important numerical reference for the optimal design of thermal deformation of the pump support in the sodium-cooled fast reactor.