690合金在核电厂一、二回路工况下的均匀腐蚀性能研究

Research on General Corrosion of Alloy 690 in Primary andSecondary Loops of Nuclear Plants

690合金是当前核电厂应用最广泛的蒸汽发生器传热管材料。传热管的破损主要是由腐蚀造成,因此有必要对690合金在核电厂工况下的耐腐蚀性能进行研究。当前对690合金的均匀腐蚀实验方法可以实现对温度、压力、介质化学成分的控制,但未考虑流质冲刷的影响。蒸汽发生器传热管在实际服役时,其一、二次侧接触的介质是高速流动的,高速流质冲刷很可能对均匀腐蚀具有促进作用。本实验通过新开发的一套搅拌装置,首次实现对介质流速的实验控制。在模拟核电厂一、二回路工况下,精确控制回路水化学和介质流速,获得了国产690合金的均匀腐蚀速率和金属腐蚀产物释放速率,并与进口同规格管材作对比,评价其耐均匀腐蚀性能。结果表明,国产690合金传热管的耐均匀腐蚀性能与进口材料基本相当;流质冲刷对690合金传热管一次侧均匀腐蚀具有一定的促进作用,而对二次侧均匀腐蚀没有明显的促进作用。

Alloy 690 is the most widely used material for steam generator(SG)heat transfer tubes of nuclear power plants.The failure of heat transfer tubes is caused mainly by corrosion.So it’s necessary to study the corrosion resistance of alloy 690 in nuclear power plant.The current experiment on general corrosion of alloy 690 can control the parameters of temperature,pressure and chemical component,but not yet consider the influence of flow.Actually,the primary and secondary water in contact with SG tubes flows at high speed,and the flow possibly has some promoting effect on general corrosion.The experimental method of this paper can control the flow rate for the first time by means of a newly developed set of agitation equipment.The experiments of general corrosion in this paper are conducted in simulated primary and secondary loops of nuclear plants,to acquire the corrosion rate and the metal corrosion product release rate of domestic alloy 690 tubes,which are compared with tubes from Valinox.In the experiments,water chemistry and flow rate are controlled accurately.The results indicate that,the general corrosion resistance of domestic alloy 690 tubes is almost equal to the imported tubes;erosion has some effect on primary general corrosion of alloy 690,but has no obvious effect on secondary general corrosion.