小型压水堆下腔室交混特性实验研究

为研究小型压水堆下腔室的交混特性，本文基于比例模化方法，开展小型压水堆1∶3比例模型水力学实验，通过测量溶液浓度变化，获得在冷管流量均衡和非均衡工况下堆芯入口的交混因子矩阵。研究结果表明，均衡流量工况下，冷管流量的变化对堆芯入口交混因子矩阵未产生明显影响；非均衡流量工况下，靠近出口管的燃料组件交混因子受流量不均衡的影响较大，而中心区域的交混因子变化幅度较小。由此可见，小型压水堆在均衡流量下具有较稳定的下腔室交混特性，而在非均衡工况下需要重点关注出口附近燃料组件交混特性的变化。 

Experimental Study on Flow Mixing Characteristics of Lower Plenum of Small PWR

In order to study the flow mixing characteristics of lower plenum of small pressurized-water reactor (PWR), this study conducts a hydraulic experiment on the reactor model in scale of 1∶3 based on the scaling method, and obtains the flow mixing factor matrices for the core inlet under the balanced and unbalanced flow conditions of the cold leg by measuring the solution concentration change. The results show that under the balanced flow condition, the changes of cold leg flow have slight effect on the core inlet flow mixing factor matrix, while under the unbalanced flow condition, the fuel assembly flow mixing factor near the outlet pipe is significantly affected by the flow unbalance, and that small change occurs to the flow mixing factor in the central region. Therefore, the flow mixing characteristics of lower plenum of small PWR are stable at the balanced flow, and focus should be put on the change in flow mixing characteristics of fuel assemblies near the outlet under the unbalanced flow condition.