Bojinov Martin, Betova Iva, Karastoyanov Vasil
Department of Physical Chemistry, University of Chemical Technology and Metallurgy, 1756 Sofia, Bulgaria.
Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
Materials (Basel). 2024 Apr 17;17(8):1846. doi: 10.3390/ma17081846.
During the power operation of the primary loop of a water cooled-water moderated energy reactor (WWER), the water chemistry evolves from a high-boron high-potassium composition to significantly lower concentrations of both constituents at the end of a campaign, and the Li concentration reaches ca. 0.7-0.9 ppm. In the present paper, the effect of primary water chemistry evolution during operation on the corrosion rate and conduction mechanism of oxides on Alloy 690 is studied by in situ impedance spectroscopy at 300 °C/9 MPa during 1-week exposures in an autoclave connected to a re-circulation loop. At the end of exposure, the samples were anodically polarized at potentials -0.8 to -0.1 V vs. SHE to evaluate the stability of the passive oxide. Simultaneously exposed samples of Alloy 690 were subsequently analyzed by XPS to estimate the thickness and in-depth composition of oxides. Impedance data were quantitatively interpreted using the mixed-conduction model (MCM) for oxide films. The effect of water chemistry evolution on the corrosion rate and conduction mechanism in the oxide on Alloy 690 in a primary coolant is discussed based on the obtained parameters.
在水冷 - 水慢化能量反应堆（WWER）一回路的功率运行期间，水化学组成从高硼高钾成分演变为在一个运行周期结束时两种成分的浓度显著降低，并且锂浓度达到约0.7 - 0.9 ppm。在本文中，通过在300°C/9 MPa下于连接再循环回路的高压釜中进行为期1周的暴露期间采用原位阻抗谱，研究了运行期间一回路水化学演变对690合金上氧化物的腐蚀速率和传导机制的影响。在暴露结束时，将样品相对于标准氢电极（SHE）在 - 0.8至 - 0.1 V的电位下进行阳极极化，以评估钝化氧化物的稳定性。随后通过X射线光电子能谱（XPS）对同时暴露的690合金样品进行分析，以估计氧化物的厚度和深度成分。使用氧化物膜的混合传导模型（MCM）对阻抗数据进行定量解释。基于所获得的参数，讨论了水化学演变对一回路冷却剂中690合金上氧化物的腐蚀速率和传导机制的影响。
