Decontamination of concrete waste from nuclear power plant decommissioning in South Korea

Abstract

This study investigates for optimizing thermal treatment conditions for the effective decontamination of cobalt(Co)-contaminated concrete waste. About 21 g of ordinary Portland cement (OPC, Type I), 37 g of dry sand, 5 g of fly ash, and 24 g of aggregates were mixed, cured for 28 days, and used for characterization and thermal treatment. Thermal treatment was conducted at different temperatures between 105 degrees C and 600 degrees C. The samples were characterized using SEM, XRD, FTIR, XRF, and XAS. Up to 600 degrees C, mass loss only occurred for water molecules in the concrete with similar to 60% volume reduction, suggesting an optimum temperature between 500 degrees C and 550 degrees C. During thermal treatment, Co phase changed from Co3O4 to CoO, and among the various chemical solutions, chloric acid exhibits the highest Co decontamination efficiency. The results suggest that a combination of thermal and chemical treatments can enhance Co removal from concrete waste. (C) 2020 Elsevier Ltd. All rights reserved.