某核电厂循环水管道牺牲阳极脱落原因及改进建议

Causes and Improvement Suggestions of Sacrificial Anode Shedding in a Nuclear Power Plant Circulating Water Pipe

某核电厂循环水管道牺牲阳极在短时间内出现非均匀溶解和局部脱落.通过化学成分分析、电化学性能测试、阳极背面涂层厚度分析及不同安装方式下海水对牺牲阳极冲刷作用的模拟,分析了牺牲阳极脱落的原因.结果表明:铟元素含量偏低导致牺牲阳极非均匀溶解;牺牲阳极背面与被保护管道之间的安装间隙较大、牺牲阳极背面涂层厚度不足以及牺牲阳极体内存在超尺寸铸造缩孔缺陷等因素均会降低牺牲阳极体与铁芯之间的结合力,进而加速牺牲阳极脱落.

Non-uniform dissolution and partial breakdown were found in aluminum sacrificial anodes in a nuclear power plant circulating water pipe in a short time.Through chemical composition analysis,electrochemical performance test,coating thickness analysis on the back of anode and the simulation of scour effect of seawater on sacrificial anodes with different installation methods,the reasons for sacrificial anode shedding were analyzed.The results showed that the low content of indium element resulted in non-uniform dissolution of sacrificial abodes.The large installation clearance between the back of sacrificial anode and protected pipe,insufficient coating thickness on the back of sacrificial anode and super-size casting shrinkage in sacrificial anode,reduced the binding force between anode body and anode iron core,and then caused sacrificial anode to fall off.