Development of a Corrosion Control Program for Liquid Radioactive Wastes Stored in Carbon Steel Waste Tanks

摘要

Large underground, carbon steel tanks are used for interim storage of liquid radioactive waste at the Hanford site. The Hanford Waste Treatment and Immobilization Plant (WTP) is being constructed to treat the high-level waste (HLW) and low-activity waste (LAW) stored in the tanks. Secondary waste will be generated by condensation and scrubbing of the LAW melter off-gas stream. A portion of this stream, which will contain substantial amounts of chloride, fluoride, ammonia, and sulfate ions, may be returned to the tank farms for storage and evaporation. Presently, there are no restrictions on the halide or sulfate concentrations of this return stream prior to transferring to the carbon steel waste tanks. Prior to initiating the process, the current corrosion control program needs to be updated to account for the susceptibility to pitting corrosion of waste tanks due to the halide content of the secondary waste. Cyclic potentiodynamic polarization tests were utilized to determine the nitrite inhibitor requirements needed to safely receive and store the secondary waste.