Abstract
The dissolution behavior of U, contained in the soils, was examined through chlorination with ZrCl4 to reduce the U concentration to clearance levels. Natural soils, composed of Si, Al, and approximately 2 ppm U, acted as surrogates for the contaminated soils. A salt mixture of LiCl-KCl-ZrCl4 was prepared in an Al2O3 crucible at 500°C, and SiO2 or natural soils were loaded for the chemical reactions. The reaction of SiO2 and Al2O3 with ZrCl4 was monitored by cyclic voltammetry, and no obvious change was observed. The results showed that SiO2 and Al2O3 were stable against ZrCl4. The reaction of natural soils with ZrCl4 indicated that the U content decreased from 2 to 1.2 ppm, while ∼0.4 ppm U appeared in the salt. Thus, the U, in the soils, dissolved into the salt by chlorination with ZrCl4. Therefore, based on these results, a new method to remediate U-contaminated soil wastes by chlorination with ZrCl4, followed by electrorefining of U, is suggested.
Highlights
Technologies that contribute to the effective decommissioning and/or dismantling of nuclear power plants are essential, especially considering that many power plants are close to the end of their design life. e dismantling of nuclear facilities produces a significant amount of radioactive waste; one such major waste is radiation-contaminated soil [1]
E following results were obtained: (i) SiO2 and Al2O3 were estimated to be stable for the chlorination with ZrCl4, while UO2 was destabilized, as indicated by the thermodynamic calculations (ii) e chlorination test of SiO2 and Al2O3, which were the main component of soils, confirmed their stability against ZrCl4 in LiCl-KCl (iii) e U in the natural soils was successfully dissolved into LiCl-KCl by chlorination with ZrCl4, even though the initial U was extremely small
Based on these results of the laboratory test that 40% of U was dissolved from natural soils into LiCl-KCl salt by the chlorination with ZrCl4, we suggest a new method to remediate the U-contaminated soils by chlorination and followed by U electrorefining
Summary
Technologies that contribute to the effective decommissioning and/or dismantling of nuclear power plants are essential, especially considering that many power plants are close to the end of their design life. e dismantling of nuclear facilities produces a significant amount of radioactive waste; one such major waste is radiation-contaminated soil [1]. Technologies that contribute to the effective decommissioning and/or dismantling of nuclear power plants are essential, especially considering that many power plants are close to the end of their design life. E dismantling of nuclear facilities produces a significant amount of radioactive waste; one such major waste is radiation-contaminated soil [1]. It is necessary to develop suitable technology for decontaminating the soil for disposal. Two research reactors and a U conversion facility have been decommissioned in Korea, generating a significant amount of radioactive soil, which is currently in temporary storage. E majority of these soils show very low-level radioactivity, i.e., 60 Bq/g Despite the extremely low levels of radioactivity, these soils are considered as radioactive waste and cannot be disposed normally. Despite the extremely low levels of radioactivity, these soils are considered as radioactive waste and cannot be disposed normally. us, decontamination of the soils, to a level below that of deregulation, is essential
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