Korea Atomic Energy Research Institute (KAERI) and Argonne National Laboratory (ANL) conducted steady-state tests at constant heat flux conditions to investigate the scale effect on heat removal behavior of the air-cooled Reactor Cavity Cooling System (RCCS). Two differently scaled-down test facilities were used in this study, KAERI’s ¼ scale with 4.0-m cavity height, and ANL’s ½ scale with 6.8-m cavity height. Two scaling laws were proposed to simulate the radiation across the cavity and the buoyancy-driven duct flow in the riser, respectively. The test matrix for KAERI and ANL test facilities focused on the scaling effect of the heated riser length with constant heat flux at the PMR200 RCCS design. The test results showed that mixed convection in the riser duct is an important factor for accurately extrapolating the thermo-fluid behavior in the prototype from the test results in the scale-down facilities. The system analysis code, GAMMA+, with improved heat transfer models predicted fairly well the air-cooled RCCS test data from two facilities. GAMMA+ analysis results showed that the predicted radiation fractions on the heated plate in the scale-down test conditions were larger than those on the reactor vessel in the prototype. The scaling law for air-cooled RCCS was improved by considering the mixed convection in the riser duct and the same radiation fraction on the heated plate. The mixed convection effect was calculated by the height ratio. The same radiation fraction provided a conservative extrapolation from the scale-down test results.

韩国原子能研究所 (KAERI) 和阿贡国家实验室 (ANL) 在恒定热通量条件下进行了稳态测试，以研究规模效应对空冷反应堆腔冷却系统 (RCCS) 的排热行为的影响。本研究中使用了两种不同比例的缩小测试设备，KAERI 的 1/4 比例尺具有 4.0 米的腔高，而 ANL 的 ½ 比例尺具有 6.8 米的腔高。提出了两个比例定律来分别模拟穿过空腔的辐射和立管中浮力驱动的管道流动。KAERI 和 ANL 测试设施的测试矩阵侧重于 PMR200 RCCS 设计中具有恒定热通量的加热立管长度的缩放效应。测试结果表明，提升管中的混合对流是从按比例缩小设施的测试结果准确推断原型中的热流体行为的重要因素。系统分析代码 GAMMA+ 具有改进的传热模型，可以很好地预测来自两个设施的风冷 RCCS 测试数据。GAMMA+ 分析结果表明，按比例缩小测试条件下加热板上的预测辐射分数大于原型中反应堆容器上的预测辐射分数。通过考虑立管内的混合对流和加热板上相同的辐射分数，改进了风冷RCCS的缩放规律。混合对流效应由高度比计算。相同的辐射分数从按比例缩小的测试结果提供了保守的推断。