Surface decontamination of radioactive metal waste using choline chloride-based deep eutectic solvents

Abstract

During the operation of nuclear reactors, a large of volume of stainless steel waste is generated, and its decontamination allows an economic disposal of the waste. Removal of radionuclides from the oxide layer of the waste reduces the level of the waste from intermediate level to low level. This can alleviate the limited storage and reduce the cost of waste disposal. Current decontamination agents utilize strong aqueous solvents such as strong acids and complexing agents or non-aqueous solvents such as ionic liquids and molten salts. However, aqueous solvents are concerned by their inherent toxicity. Ionic liquids are too expensive to apply in industrial processes, and molten salts require a high temperature, which is not easy for an industrial application. In this thesis, a decontamination scheme for stainless steel waste using deep eutectic solvents, an inexpensive room-temperature liquid, is studied. Simulated stainless steel specimens are leached in various conditions of deep eutectic solvents to assess the decontamination feasibility. Metal behaviors in the solvents are studied to understand the results and suggest a liquid recycling method for the used liquid.