Influence of flow on the corrosion behavior of pure iron in simulated geological repository conditions

As the first barrier in direct contact with high-level waste (HLW) during deep geological disposal, the corrosion behavior of the metal canister in deep groundwater directly affects the longevity and effectiveness of the disposal process. In this paper, we investigated the corrosion behavior of pure iron under different flowing conditions through electrochemical tests, weightlessness tests combined with characterization analysis. The results showed that in SG (simulated groundwater) and SG + CaCl2 solutions, the increase of flow velocity improved the mass transfer rate, resulting in the gradual increase of the corrosion rate, and when the flow velocity reached a certain degree, the loose corrosion products became denser, which led to the decline of the corrosion rate. In the SG + Na2CO3/Na2SiO3 solutions, the flow of the medium would promote the formation of stable passivation film, resulting in the improvement of the corrosion resistance of pure iron. The corrosion products of pure iron in simulated flowing groundwater were mainly composed of FeOOH, Fe2O3 and Fe3O4, while the passive film was mainly consisted of siderite, silica and silicate.