Abstract

The Molten Salt Reactor Experiment (MSRE), which operated at Oak Ridge National Laboratory from 1965 to 1969, was an experimental reactor that used UF₄ fuel dissolved in molten fluoride salt. Criticality was achieved when the fuel salt mixture passed through the graphite-moderated core region. Therefore, because the fuel and fission products flowed through the system, delayed neutron precursors were not confined to the core, and decay heat was released outside the core, which is a unique challenge relative to more traditional reactor designs with solid fuel. Therefore, research and demonstration reactors such as MSRE have become a valuable source of information for benchmarking modeling and simulation tools for advanced reactor designs. One such tool being considered is GOTHIC, which is a coarse-grid computational fluid dynamics multiphysics software package. GOTHIC includes attributes and physical phenomena needed for modeling these advanced, non–light water reactor designs. For example, GOTHIC includes fluid property tables for various molten salts; a tracer-tracking module for modeling fission products and the radioactive decay and heat release by delayed neutron precursors locally in the fluid outside the core; and other necessary capabilities for modeling molten salt reactor (MSR) designs, including the ability to model dissolved gases. GOTHIC is used to benchmark steady-state and transient conditions from the MSRE. Zero-power physics testing included fuel salt pump start-up and coast-down transients with a control rod automatically moving to maintain criticality. The control rod motion calculated by GOTHIC is a reasonable match to measured data from these transients. Further, low-power testing included a natural convection transient with no control rod motion such that reactor power was responding to heat load demand from the radiator. The reactor power and fuel salt and coolant salt temperatures calculated by GOTHIC exhibit good agreement with measured data. These results confirm GOTHIC capabilities for modeling MSR designs with circulating fuel.

摘要

1965 年至 1969 年在橡树岭国家实验室运行的熔盐反应器实验 (MSRE) 是一个使用 UF ₄的实验反应器燃料溶解在熔融的氟化盐中。当燃料盐混合物通过石墨缓和的核心区域时达到临界状态。因此，由于燃料和裂变产物流经系统，延迟中子前驱体不限于堆芯，衰变热在堆芯外释放，相对于使用固体燃料的更传统的反应堆设计而言，这是一个独特的挑战。因此，MSRE 等研究和示范反应堆已成为先进反应堆设计基准建模和仿真工具的宝贵信息来源。正在考虑的一个这样的工具是 GOTHIC，它是一个粗网格计算流体动力学多物理场软件包。GOTHIC 包括为这些先进的非轻水反应堆设计建模所需的属性和物理现象。例如，GOTHIC 包括各种熔盐的流体特性表；一个示踪剂跟踪模块，用于模拟裂变产物以及堆芯外流体中局部延迟中子前体的放射性衰变和放热；以及模拟熔盐反应堆 (MSR) 设计的其他必要功能，包括模拟溶解气体的能力。GOTHIC 用于对来自 MSRE 的稳态和瞬态条件进行基准测试。零功率物理测试包括燃料盐泵启动和滑行瞬变，控制棒自动移动以保持临界状态。由 GOTHIC 计算的控制棒运动与这些瞬变的测量数据合理匹配。更远，低功率测试包括无控制棒运动的自然对流瞬态，以便反应堆功率响应散热器的热负荷需求。GOTHIC 计算的反应堆功率和燃料盐和冷却剂盐温度与实测数据显示出良好的一致性。这些结果证实了使用循环燃料对 MSR 设计进行建模的 GOTHIC 能力。