Abstract
Numerous low-level and intermediate-level radioactive wastes are generated from the decommissioning processes of nuclear power plants; these wastes are immobilized to prevent the release of radionuclides under disposal conditions. In this study, we investigated the leaching behavior of Cs, Sr, Co, and Eu, which are common in immobilized decommissioning wastes. Ordinary Portland cement (OPC) was used as an immobilization agent. During the test, leaching of the nuclides occurred in the order of Cs, Sr, Co, and Eu and decreased over time. The results showed that 41.4% of the total Cs leached over 90 days, although the other elements leached in quantities less than 1.5%. CaCO3 was precipitated by the release of cementitious materials, indicating carbonation of the leachate. The leachability indexes in all cases exceeded the acceptable criteria (>6). The results of the present study suggest that OPC can be effectively used as a binding material to immobilize nuclides (Cs, Sr, Co, and Eu) contained in decommissioning wastes.
Highlights
Many facilities that use nuclear and other radioactive materials are expected to shut down in the near future as they reach the ends of their operating lifetimes [1]
Radioactive wastes are produced mostly from the operation or decommissioning of nuclear facilities and unexpected leakages from nuclear power plants [2,3]. These radioactive wastes are classified as High-Level Waste (HLW), Intermediate-Level Waste (ILW), Low-Level Waste (LLW), and Very-Low-Level Waste (VLLW) [4,5]
The pH value of the ultrapure water used in the test was about 5.6 because the ultrapure water was exposed to carbon dioxide in the atmosphere
Summary
Many facilities that use nuclear and other radioactive materials are expected to shut down in the near future as they reach the ends of their operating lifetimes [1]. Radioactive wastes are produced mostly from the operation or decommissioning of nuclear facilities and unexpected leakages from nuclear power plants [2,3] These radioactive wastes are classified as High-Level Waste (HLW), Intermediate-Level Waste (ILW), Low-Level Waste (LLW), and Very-Low-Level Waste (VLLW) [4,5]. Radioactive wastes, such as ILW and LLW, produced from decommissioning processes are disposed in near-surface facilities and landfills to isolate these wastes from the natural ecosystem for sufficient periods of time [6,7,8]. Fluidizable radioactive wastes such as concentrated wastes, spent resins, sludge, and dry active wastes must be solidified or immobilized homogeneously to limit the release of radionuclides and maintain the structural integrity of the disposal environment [9]
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