Abstract
Radioactive waste is stored in carbon-steel double-shell tanks at the Hanford site. The waste is transferred between the tanks and other assets using transfer lines that consist of carbon steel encased carrier and casing pipes. Recent inspection data of the transfer lines have shown extensive corrosion on both interior of the casing and exterior of the carrier pipes. The visual inspections have shown presence of extensive amount of corrosion products near the pipeline risers and beyond. It has been hypothesized that the corrosion is predominantly due to the high humidity conditions driven by raw water accumulation used during hydrotesting and by water accumulation due to the cold fingering effect. Drying of the transfer lines could lead to corrosion mitigation. Experimental studies were conducted to understand the effect of environmental conditions, especially, relative humidity and temperature, on the initiation of corrosion and mitigation of pre-existing pitting corrosion. The experimental conditions are selected based on the seasonal temperature changes, and relative humidity conditions ranging from 30 to 100 percent. The experimental data were used to determine the operation parameters that could mitigate the corrosion.
