Abstract
Legacy nuclear process waste is stored in 1,000 kgal (3,780 kL) capacity, underground, carbon steel, double-shell tanks on the Hanford Site. Many of these tanks contain a considerable quantity of settled solids under a nitrate-rich supernatant liquid, and the solids can have a large chemical diversity due to the receipt of waste from multiple plutonium separation and waste management processes over several decades of use. Therefore, knowing the chemical content through the entirety of the waste is critical to assessing the risk of corrosion. This challenge is further increased by the radiological risks imposed by the hazards of handling the waste during chemical characterization and testing. A tank waste sampling strategy has been developed to profile the chemical diversity in the storage tanks, and the subsequent samples are used to support corrosion testing for corrosion risk assessments of the tank bottom, liquid-to-air interface, and chemically unique waste layers. Additional information is obtained from a tank potential monitoring program to ensure the tank steel is below critical pitting and cracking potentials. Together, the corrosion testing and tank potentials are used to minimize corrosion risks, ensuring the integrity of the double-shell storage tanks is maintained on the Hanford Site.
