核电厂定子冷却水泵切换失败原因分析

Cause Analysis on Switching Failure of Stator Cooling Water Pump in Nuclear Power Plant

国内某核电厂定子冷却系统运行泵在切换到备用泵过程中曾多次发生切换失败现象。对该机组定子冷却水泵历史切换情况、系统管路布置、泵性能、出口逆止阀弹簧断裂情况进行了收集与分析,明确了泵切换失败的主要原因为运行泵出口逆止阀弹簧断裂,备用泵出口逆止阀弹簧完好,备用泵启动时无法克服逆止阀弹簧力;次要原因为备用泵叶轮直径相对运行泵偏小,导致泵性能出力不足。明确原因后对出口逆止阀进行了改造,备用泵能正常切换。

In a domestic nuclear power plant,the operating pump of the stator cooling system has failed to switch many times during the process of switching to the standby pump.This paper collects and analyzes the historical switching situation of the stator cooling water pump of the unit,system piping layout,pump performance,and outlet check valve spring rupture.The main reason for the failure of pump switching is determined to be the break of the check valve spring at the outlet of the running pump,the check valve spring at the outlet of the standby pump is intact,and the spring force of the check valve cannot be overcome when the standby pump is started;the secondary reason is that the impeller diameter of the standby pump is smaller than the impeller diameter of running pump,resulting in insufficient pump performance.After clarifying the reason,the outlet check valve is modified,and the standby pump can be switched normally.