Development of prediction method of flow accelerated corrosion (2). Evaluation of water-chemical factors and proposal of prediction model

The prediction model of flow accelerated corrosion (FAC) rate based on the FAC mechanism is required in the wall thinning management of the power plant. The dominant factors of FAC are water chemistry, material, and fluid dynamics. It is expected that the solubility of iron can express the effect of water chemistry on FAC. The correlation between solubility and FAC rate has not been adequately discussed. In this study, a novel model of chemical effect on FAC that was developed by taking into account the diffusion of iron, chromium, dissolved hydrogen and dissolved oxygen and under steady-state condition is proposed. The FAC model reproduces qualitatively effect of major water chemistry parameters on FAC rate. The equation to evaluate a critical dissolved oxygen concentration for FAC suppression is also proposed. (author)