Radionuclides in low- and intermediate-level radioactive wastes from the decommissioning process of nuclear power plants were generally immobilized by cementation methods. Ethylenediaminetetraacetic acid (EDTA), which is extensively used as a decontamination agent, can affect the behaviors of radionuclides immobilized in cement waste forms. In this study, the effects of EDTA contained in simulated radioactive decommissioning wastes on the leaching characteristics of immobilized Co and Cs and the microstructure evolution of cement waste form. Co leaching was accelerated by the formation of Co–EDTA complexes with high mobility and solubility. Cs leaching was hindered by the ion competition with other metal–EDTA complexes for releasing from the cement waste form. Cs leaching was also retarded by carbonated layer at edge of the cement waste form, which process is facilitated by the presence of EDTA. Finally, the effects of EDTA on the leaching characteristics of immobilized Cs and Co and the microstructure evolution of the cement waste form should be considered to ensure the safety of disposal for lowand intermediate-level radioactive wastes.

• Ja-Young Goo(Korea Atomic Energy Research Institute (KAERI), Korea University) Corresponding author
• Seonggyu Choi(Korea Atomic Energy Research Institute (KAERI))
• Bong-Ju Kim(Korea Atomic Energy Research Institute (KAERI))
• Jongtae Jeong(Korea Atomic Energy Research Institute (KAERI))
• Jang-Soon Kwon(Korea Atomic Energy Research Institute (KAERI))
• Ho Young Jo(Korea University)