Abstract
The corrosion behaviors of A106B carbon steel and 304L stainless steel (SS) in seawater with different Cu2+ concentrations were studied by the immersion test and the potentiodynamic polarization test. The results showed that with the increasing Cu2+ concentration, the mass lot rates of A106B and 304L SS all increased in the immersion test, and compared with A106B, the mass lot rates of 304L SS were all smaller. In the potentiodynamic polarization test, following the concentration of Cu2+ increased, the corrosion potential of A106B firstly shifted negatively; then, when Cu2+ increased to 100 ppm, the polarization curve moved to the upper right direction; namely, both the corrosion potential and corrosion electrical density increased. The corrosion potential of 304L SS increased with the increasing Cu2+, and the passive region was reduced; the pitting sensitivity improved.
Highlights
The important plant water system (SEC system), i.e., the safety plant water system, function was to transfer the heat from the structures, systems, and components related to safety to the final sink-seawater under normal operation and accident conditions
In the existing nuclear power plants, the SEC pipes were made of stainless steel [2, 3], carbon steel lined with coating, rubber, plastic or cement mortar, and resin pipes
During the service of the SEC pipes, the addition of the cupric fungicide to prevent microbial corrosion, the corrosion of copper components, or other reasons could lead to the local enrichment of Cu2+ in the SEC system and the precipitation of Cu on the surface of components; the interaction between Cu2+ and seawater may accelerate the corrosion of SEC system material, even leading to the breaking of the components and inducing the addition of Cu2+ into the secondary circuit system
Summary
The important plant water system (SEC system), i.e., the safety plant water system, function was to transfer the heat from the structures, systems, and components related to safety to the final sink-seawater under normal operation and accident conditions. The corrosion of steels in seawater had been widely investigated all over the world [4–20], and the influence of Cu2+ on material corrosion is mainly focused on different materials in nonseawater environment, such as steel [21–30], aluminum alloy [31, 32], 690 alloy [33], and copper alloy [34]. The works focused on the corrosion behavior of steels in seawater containing Cu2+ and the influence of the Cu2+ and copper oxides on the corrosion of the equipment in the secondary circuit system were little reported [35]. The corrosion behaviors of steels in seawater containing Cu2+ were studied by the immersion test, potentiodynamic polarization, and SEM observation, which could provide a certain basis and guidance for the operation of nuclear power stations
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