Study on Hydrodynamic Characteristics of Transient Process of Reactor Coolant Pump Shaft Stuck Accident
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摘要: 为探究核主泵卡轴事故瞬变过程的水动力特性,通过动态匹配核主泵水力特性与系统管路阻力特性,建立了反应堆一回路系统的全三维简化模型。借助计算流体动力学(CFD)方法对核主泵卡轴事故工况进行了瞬态数值模拟,得到不同卡轴工况下核主泵外特性、内部压力场、叶轮叶片载荷与受力特性的瞬时变化。研究表明:卡轴时间越短,核主泵相应特性参数的瞬时变化越剧烈,事故造成影响越严重。以叶轮转速刚降为0 r/min时为节点,在卡轴时间为0.1、0.3、0.5 s三种卡轴工况下,流量分别降低到正常运行时的82.3%、61.4%、49.6%;核主泵扬程达到反向极值,分别为正常运行时的−137.7%、−87.4%、−56.9%;叶轮叶片两侧压力差值达到最大,分别为1.34、0.73、0.47 MPa,且在叶轮叶片工作面一侧和导叶流道中间部分形成相对集中的低压区;叶轮所受轴向力达到反向极值,分别为正常运行时的−159.3%、−96.5%、−65.5%。本数值预测方法对反应堆水动力系统的动态安全性评估提供了一定的数据支撑。Abstract: In order to explore the hydrodynamic characteristics of transient process of the reactor coolant pump shaft stuck accident, a full three-dimensional simplified model of the reactor primary circuit system was established by dynamically matching the hydraulic characteristics of the reactor coolant pump and the resistance characteristics of the system pipeline. The transient numerical simulation of the reactor coolant pump shaft stuck accident condition is carried out by using the computational fluid dynamics (CFD) method, and the transient variations of external characteristics, internal pressure field, impeller blade load and force of the reactor coolant pump under different shaft stuck conditions are obtained. The study shows that the shorter the shaft stuck time, the more dramatic the transient variation of the reactor coolant pump characteristic parameters, and the more serious the impact of the accident. Taking the moment when the impeller speed just drops to 0 r/min as the node, under three shaft stuck conditions (i.e. shaft stuck time = 0.1 s, 0.3 s and 0.5 s), the flow rate decreases to 82.3%, 61.4% and 49.6%, respectively, of that under the normal operation. The head of the reactor coolant pump reaches the reverse extreme value, i.e. −137.7%, −87.4% and −56.9% , respectively, of the value under the normal operation. The pressure difference between the two sides of the impeller blade reaches the maximum, i.e. 1.34 MPa, 0.73 MPa and 0.47 MPa, respectively, and a relatively concentrated low-pressure area is formed on the side of the blade working surface in the impeller blade and in the middle part of the guide vane flow channel. The reverse extreme value of the axial force on the impeller reaches −159.3%, −96.5% and −65.5%, respectively, of the value under the normal operation. The numerical prediction method provides certain data support for the dynamic safety assessment of the reactor hydrodynamic system.
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表 1 核主泵额定参数
Table 1. Rated Parameters of Reactor Coolant Pump
参数名 参数值 额定流量/(m3·h−1) 24680 设计扬程/m 102.8 额定转速/(r·min−1) 1485 参考压力/MPa 15.5 叶轮叶片数 4 导叶叶片数 11 -
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