模拟压水堆一回路条件添加Pt技术研究

采用SEM,XPS,XRD和电感耦合等离子体原子发射光谱(ICP-AES)法并结合线性极化曲线研究了模拟压水堆一回路加氢水化学条件下预氧化的316LN不锈钢表面沉积贵金属Pt的方法及其对材料电化学行为的影响。结果表明,预氧化实验中,材料表面形成了双层氧化膜,外层为富Ni层,内层为富Cr层,与反应堆实际运行中材料表面产生的氧化膜结构和成分相似;在模拟热停堆实验条件下,用Na2Pt(OH)6配制含Pt量为0,10,50和100μg·kg-1的溶液能够在316LN材料表面沉积达到目标要求的Pt。电化学实验结果表明,Pt沉积量越多,材料的腐蚀电流密度变化越小,腐蚀电位急剧降低,说明材料抗腐蚀性能提高。

Effect of Pt Deposit on Corrosion Behavior of 316LN in Simulated Primary Loop Water Environment of Pressurized Water Reactor

A method of Pt deposition on a pre-oxidized 316LN steel surface was developed in an artificial environment, which aims to simulate hydrogenated water chemistry (HWC) condition of the primary loop of PWR and then its effect on the electrochemical behavior in the same environment of the structural material 316LN steel was studied by SEM, XPS, XRD, ICP-AES and linear dynamic polarization etc. At first, all the test steel samples were exposed in 320 ℃water with less than 100 μgkg^-1 oxygen for 400 h in order to form an oxide scale on the steel surface. Next, the pre-oxidized steel were immersed for 48 h at 150 ℃ to the water with addition of Na₂Pt(OH)₆ to deposit Pt (0, 10, 50 and 100 μgkg^-1, respectively) on the pre-oxidized steel. Finally, the samples were exposed to 300 ℃ high temperature water with ＜100 μgkg^-1 oxygen, 200 μgkg^-1 hydrogen while measuring the linear polarization curve of the treated steel. The result showed that a two layered oxide scale with the Ni-rich outer layer and Cr-rich inner layer were form on the steel, which is similar to the oxide scale formed during PWR service; the amount of the deposited Pt on the pre-oxidized steel was from 4.37 to 7.37 μgcm^-2 while the water containing Pt from 10 to 100 μgkg^-1. With the increase of the Pt concentration of the treated solutions, E_corr decreased sharply while current density slightly changed, which revealed that the pre-oxidized steel samples with Pt deposit exhibit a better corrosion resistance.