The major objective of the present study is to verify a method for the FLUENT code applying the user defined function (UDF) which enables the coupling simulation of neutronics and thermal-hydraulics of a molten salt fast reactor based on the one-point kinetics. The UDF with the added logic to control the control rod drive (CRD) is linked to the FLUENT code to analyze the reactivity change when the fuel pump of the molten salt reactor MSRE was started and tripped. These experiments were carried out under zero power conditions. The core of the MSRE is modeled on a cylinder with the same flow channel area as MSRE, and the control rod in the simulation model can compensate for the reactivity changes that accompany with the flow rate changes. When the pump is started, the response of the control rod overshoots because the reactivity change is in a form close to the stepwise change. This behavior has been reproduced almost correctly using a simple proportional-integral-derivative (PID) controller program. The response when the control constant is changed has been also investigated. In the fuel pump trip experiment, the transient change is relatively moderate. This behavior is also reproduced almost correctly with the same control logic. These simulations show that the UDF has been programmed correctly, and the discretized point kinetic model with prompt jump assumption can be applied to the molten salt reactor in combination with the code-to-code benchmarks already performed.

本研究的主要目的是验证一种使用用户定义函数（UDF）的FLUENT代码的方法，该方法能够基于单点动力学对熔盐快堆的中子学和热工流体进行耦合仿真。具有附加逻辑以控制控制杆驱动器（CRD）的UDF链接到FLUENT代码，以分析启动和跳闸熔融盐反应堆MSRE的燃料泵时的反应性变化。这些实验是在零功率条件下进行的。MSRE的核心建模在具有与MSRE相同的流道面积的圆柱体上，并且仿真模型中的控制杆可以补偿与流速变化相伴的反应性变化。泵启动后，控制杆的响应过冲，因为反应性变化呈接近逐步变化的形式。使用简单的比例积分微分（PID）控制器程序，几乎可以完全重现此行为。还研究了控制常数改变时的响应。在燃油泵行程试验中，瞬态变化相对适中。使用相同的控制逻辑几乎也可以正确再现此行为。这些仿真表明，UDF已正确编程，并且可以结合已经执行的代码到代码基准将具有快速跳跃假设的离散点动力学模型应用于熔盐反应堆。使用简单的比例积分微分（PID）控制器程序，几乎可以完全重现此行为。还研究了控制常数改变时的响应。在燃油泵行程试验中，瞬态变化相对适中。使用相同的控制逻辑几乎也可以正确再现此行为。这些仿真表明，UDF已正确编程，并且可以结合已经执行的代码到代码基准将具有快速跳跃假设的离散点动力学模型应用于熔盐反应堆。使用简单的比例积分微分（PID）控制器程序，几乎可以完全重现此行为。还研究了控制常数改变时的响应。在燃油泵行程试验中，瞬态变化相对适中。使用相同的控制逻辑几乎也可以正确再现此行为。这些仿真表明，UDF已正确编程，并且可以结合已经执行的代码到代码基准将具有快速跳跃假设的离散点动力学模型应用于熔盐反应堆。