Decontamination of uranium-contaminated concrete

This study examined the decontamination method by washing with nitric acid for uranium contaminated concrete pieces produced from the decommissioning of a uranium conversion plant and evaluated the amount of waste sludge generated from the treatment. In addition, carbonate solution, nitric acid and sulfuric acid were used as the extraction reagents for the uranium, and their efficiencies were also compared. For concrete pieces coated with and without epoxy, the separation method of cement paste from aggregates was preferable to the leaching of uranium from concrete because of its simpler decontamination process. When concrete pieces with epoxy were heated for 2 h at 400 °C, pulverized and sequentially washed with 0.1, 2.0 and 1.0 M of nitric acid, their radioactivity reached below the limit value of uranium for self-disposal. Unlike previous results, uranium dissolved in 1 and 2 M sulfuric acid solutions was not removed by strong anion exchange resins such as IRA 910 and Ag1×8.