• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.340-341
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• 2017

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.366-367
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• 2017

• Environmental Engineering Research
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• v.24 no.1
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• pp.173-179
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• 2019

Prussian blue (PB) is known to be an effective material for radioactive cesium adsorption, but its nano-range size make it difficult to be applied for contaminated water remediation. In this study, a simple and versatile approach to immobilize PB in the supporting matrix via surface functionalization was investigated. The commercially available poly vinyl alcohol (PVA) sponge was functionalized by acrylic acid (AA) to change its major functional group from hydroxyl to carboxylic, which provides a stronger ionic bond with PB. The amount of AA added was optimized by evaluating the weight change rate and iron(III) ion adsorption test. The FTIR results revealed the surface functional group changing to a carboxyl group. The surface functionalization enhanced the attachment of PB, which minimized the leaching out of PB. The $Cs^+$ adsorption capacity significantly increased due to surface functionalization from 1.762 to 5.675 mg/g. These findings showed the excellent potential of the PB-PAA-PVA sponge as a cesium adsorbent as well as a versatile approach for various supporting materials containing the hydroxyl functional group.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.05a
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• pp.401-402
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• 2018

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.10a
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• pp.241-242
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• 2017

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.342-343
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• 2017

• Journal of Korean Society of Water and Wastewater
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• v.27 no.2
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• pp.155-164
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• 2013

The main purpose of this research was to examine the adsorption/ion exchange characteristics of radioactive species such as cesium and strontium onto synthetic Na-birnessite (sodium-birnessite). As part of efforts to investigate the sorption behavior of cesium and strontium onto synthetic Na-birnessite, batch isotherm tests were performed under different experimental conditions. Na-birnessite was synthesized by the oxidation of $Mn^{2+}$ ions in sodium hydroxide solution. The synthetic Na-birnessite was characterized by powder x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) surface area analysis. Cesium and strontium concentrations were determined by atomic absorption spectroscopy (AAS). The removal efficiency of strontium by Na-birnessite was around 95 % which was much higher than that of cesium (~ 32 %). The results imply that strontium has a higher affinity for Na-birnessite than cesium because strontium, divalent cation leads to larger electrostatic attraction than monovalent cesium.

• Journal of Radiation Industry
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• v.9 no.4
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• pp.209-216
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• 2015

It has been about 5 years since the Fukushima nuclear power plant accident, which contaminated large area with radioactive materials. It is necessary to assess radiation dose to establish evacuation areas and to set decontamination goal for the large contaminated area. In this study, we assessed temporal trend of radiation dose to the public living in the large area contaminated with radioactive materials after the Fukushima nuclear power plant accident. The dose assessment was performed based on Chernobyl model and RESRAD model for two evacuation lift areas, Kawauchi and Naraha. It was reported that deposition densities in the areas were $4.3{\sim}96kBq\;m^{-2}$ for $^{134}Cs$, $1.4{\sim}300kBq\;m^{-2}$ for $^{137}Cs$, respectively. Radiation dose to the residents depended on radioactive cesium concentrations in the soil, ranging $0.11{\sim}2.4mSv\;y^{-1}$ at Kawauchi area and $0.69{\sim}1.1mSv\;y^{-1}$ at Naraha area in July 2014. The difference was less than 5% in radiation doses estimated by two different models. Radiation dose decreased with calendar time and the decreasing slope varied depending on dose assessment models. Based on the Chernobyl dosimetry model, radiation doses decreased with calendar time to about 65% level of the radiation dose in 2014 after 1 year, 11% level after 10 years, and 5.6% level after 30 years. RESRAD dosimetry model more slowly decreased radiation dose with time to about 85% level after 1 year, 40% level after 10 years, and 15% level after 30 years. The decrease of radiation dose can be mainly attributed into radioactive decays and environmental transport of the radioactive cesium. Only environmental transports of radioactive cesium without consideration of radioactive decays decreased radiation dose additionally 43% after 1 year, 72% after 3 years, 80% after 10 years, and 83% after 30 years. Radiation doses estimated with cesium concentration in the soil based on Chernobyl dosimetry model were compared with directly measured radiation doses. The estimated doses well agreed with the measurement data. This study results can be applied to radiation dose assessments at the contaminated area for radiation safety assurance or emergency preparedness.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3957-3961
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• 2022

Deposition behaviors of Sr and Cs in various liquid cathodes, such as Zn, Bi, Cd, and Pb, were examined to evaluate their recovery from LiCl-KCl eutectic salt. Cations in the salt were deposited on the liquid cathode, exhibiting potential of -1.8 to -2.1 V (vs. Ag/AgCl). Zn cathode had successful deposition of Sr and exhibited the highest recovery efficiency, up to 55%. Meanwhile, the other liquid cathodes showed low current efficiencies, below 18%, indicating LiCl-KCl salt decomposition. Sr was recovered from the Zn cathode as irregular rectangular SrZn₁₃ particles. A negligible amount of Cs was deposited on the entire liquid cathode, indicating that Cs was hardly deposited on liquid cathodes. Based on these results, we propose that liquid Zn cathode can be used for cleaning Sr in LiCl-KCl salt.

• Economic and Environmental Geology
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• v.51 no.2
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• pp.113-120
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• 2018

Radioactive cesium($^{137}Cs$) can be released into the environment through severe nuclear accidents such as the Chernobyl and Fukushima, The $^{137}Cs$ is one of major monitoring radionuclides due to its chemical toxicity, ${\gamma}$ radiation and long half-life($t_{1/2}=30.2yrs$). It has been known well that illite adsorb selectively and strongly the cesium due to frayed edge sites. The quantity of the FES in the illite could be controlled by weathering processes. Therefore, this study was modified illite samples through artificial weathering in the laboratory to increase sorption efficiency for cesium. Abundant interlayer cations(i.e., K, Ca) were eluted within 1 day, while Si and Al were gradually released from the crystal structure. In addition, broad peaks of XRD indicated the occurrence of chemical weathering. The cesium sorption distribution coefficients increased up to approximately 2 times after the weathering. These results suggested that sorption capacity of illite could be enhanced for cesium through artificial weathering under low temperature.