Corrosion Behavior of Carbon Steel in Flowing Water Contaminated by Seawater

Abstract

At the spent fuel pool of the Fukushima Daiichi Nuclear Power Plant, it was necessary to reduce the possibility of corrosion caused by salt contamination. For the carbon steel piping used in the alternative system for cooling the spent fuel pool, careful consideration must be given to corrosion caused by the flow of diluted seawater. In this paper, studies on the corrosion behavior of carbon steel in flowing water containing seawater are reviewed. In fluid-diluted artificial seawater, the corrosion rate of carbon steel decreases significantly with the test time, and the difference in corrosion behavior depending on the flow rate is relatively small. The addition of inorganic corrosion inhibitors such as sodium nitrite and sodium pentaborate is effective in suppressing the corrosion of carbon steel. The effect of flow rate on the critical concentration of the inorganic corrosion inhibitor required for corrosion control depends on the inhibitor. The critical concentration of nitrite ion is affected by the flow rate, whereas that of pentaborate ion is not. Purification of water is an effective in controlling carbon steel corrosion under various flow conditions.