双环路压水堆非对称入口条件下物理-热工特性研究

双环路压水堆存在反应堆入口流量、温度不对称的非正常运行工况。本文建立了基于CFD方法的反应堆整体三维流场模型，并耦合中子动力学计算程序和RELAP5程序，对这种非对称入口条件下的反应堆物理-热工特性进行了数值模拟。结果表明：反应堆入口流量不对称会加剧堆芯入口流量分配的不均匀性，并进一步导致局部功率变化，对反应堆安全不利；在入口温度不对称的条件下，冷却剂在下腔室的混合非常不充分，并导致堆芯入口温度分布不均匀，引起局部功率变化较大，对反应堆安全不利。

Operation Behaviors of Pressure Water Reactor With Double Loops Under Asymmetrical Inlet Conditions

The pressure water reactor (PWR) with double loops exists abnormal operation mode with asymmetrical coolant flux and temperature on the inlet of reactor. The paper constructs a local three dimensional thermal-hydraulics model applying computational fluid dynamics (CFD) method and coupling with three dimensional neutron kinetics code. Using this model, a numerical simulation of the reactor neutron kinetics and thermal hydraulics behavior was realized on the asymmetrical reactor inlet condition. The coolant mixing inside the reactor pressure vessel was analyzed using CFD method in detail. The effects of dissymmetrical reactor inlet coolant flux and temperature on core coolant flux and neutron flux distribution were researched. The computational results were compared with the results computed by RELAP5 code. The results demonstrate that the reactor asymmetrical inlet condition sharply increases the heterogeneity of the core inlet coolant flux and temperature distribution, ulteriorly induces the heterogeneity of reactor power distribution, and finally results in the increase of core power distribution peak factor. It also can be concluded that the more accurate CFD method and three dimensional neutron kinetics code based on neutron diffusion method are necessary for steady-state and transient/accident analysis on reactor asymmetrical inlet condition.