• Nuclear Engineering and Technology
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• 제52권2호
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• pp.328-336
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• 2020

Cesium is a major product of uranium fission, which is the most commonly existed radionuclide in radioactive wastes. Various technologies have been applied to separate radioactive cesium from radioactive wastes, such as chemical precipitation, solvent extraction, membrane separation and adsorption. Crown ethers and calixarenes derivatives can selectively coordinate with cesium ions by ion-dipole interaction or cation-π interaction, which are promising extractants for cesium ions due to their promising coordinating structure. This review systematically summarized and analyzed the recent advances in the crown ethers and calixarenes derivatives for cesium separation, especially focusing on the adsorbents based on extractants for cesium removal from aqueous solution, such as the grafting coordinating groups (e.g. crown ether and calixarenes) and coordinating polymers (e.g. MOFs) due to their unique coordination ability and selectivity for cesium ions. These adsorbents combined the advantages of extraction and adsorption methods and showed high adsorption capacity for cesium ions, which are promising for cesium separation The key restraints for cesium separation, as well as the newest progress of the adsorbents for cesium separation were also discussed. Finally, some concluding remarks and suggestions for future researches were proposed.

• 한국환경과학회지
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• 제12권10호
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• pp.1061-1069
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• 2003

The adsorption behaviors of strontium and cesium ions on fly ash, natural zeolites, and zeolites synthesized from fly ash were investigated. The zeolites synthesized from fly ash had greater adsorption capabilities for strontium and cesium ions than the original fly ash and natural zeolites. The maximum adsorption capacity of synthetic zeolite for strontium and cesium ions was 100 and 154 mg/g, respectively, It was found that the Freundlich isotherm model could fit the adsorption isotherm. The distribution coefficients (K$\_$d/) for strontium and cesium ions were also calculated from the adsorption isotherm data, The distribution coefficients decreased with increasing equilibrium concentration of strontium and cesium ions in solution. By studying the removal of cesium and strontium ions in the presence of calcium, magnesium, sodium, potassium, sulfate, nitrate, nitrite, and EDTA (in the range of 0.01 - 5 mM) it was found that these coexistence ions competed for the same adsorption sites with strontium and cesium ions.

• 환경위생공학
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• 제19권4호
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• pp.1-8
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• 2004

This study has been investigated to analyze the thermal stability of cesium reacted with fly ash with changing mole ratio of Cs/Al in hydrogen atmosphere. When the $CsNO_3$ and fly ash were reacted at $1000^{\circ}C$ in hydrogen atmosphere, cesium $nepheline(CsAlSiO_4)$ Phase began to emerge in addition to $pollucite(CsAlSi_2O_6)$ phase when the cesium loading quantity was greater than $0.32(g-Cs_2O/g-fly\; ash)$. Cesium $nepheline(CsAlSiO_4)$ Phase increased with increasing cesium loading quantity. When cesium trapped on a fly ash was exposed to $1200^{\circ}C$ in hydrogen atmosphere, no weight loss due to the volatilization was shown until the cesium loading quantity was reached at $0.32(g-Cs_2O/g-fly\; ash)$. In the case of the cesium loading quantity of $0.48-0.74(g-Cs_2O/g-fly\;ash)$ in hydrogen atmosphere, the weight loss increased with increasing the cesium loading quantity. This is considered to be due to the cesium $nepheline(CsAlSiO_4)$ whose vapor pressure is higher than that of $pollucite(CsAlSi_2O_6)$.

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1145-1152
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• 2024

To realize an initial objective of the negative ion-based neutral beam injection (N-NBI) at the Comprehensive Research Facility for Fusion Technology (CRAFT) test facility, which targets an H⁰ beam power of 2 MW at an energy of 200-400 keV and a pulse duration of 100 s, it is crucial to study the cesium dynamics of the negative ion source. Here a numerical simulation program CSFC3D is developed and applied to simulate the distribution and time dynamics of cesium during short pulses. The calculations show that most of the cesium on the plasma grid (PG) area originates from the release of cesium that is accumulated within the ion source in the plasma phase. Increasing the wall temperature reduces the loss of cesium on the wall of the ion source. Furthermore, the thickness of the cesium monolayer is directly influenced by the PG temperature. Both simulated and experimental results demonstrate that maintaining the PG temperature between 180 ℃ and 200 ℃ is essential for enhancing the performance of the ion source and optimizing the cesium behavior.

• Current Optics and Photonics
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• 제2권5호
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• pp.443-447
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• 2018

We propose a diode-pumped cesium laser using frequency locking of a pump laser that can effectively increase the maximum output power of the cesium laser. We simultaneously monitored the absorption spectrum of cesium and the laser output power, and the frequency of pump laser was locked at the center of the $D_2$ absorption line of the cesium atom to obtain an effective gain enhancement. Using this scheme, we have achieved output power increase of ~0.1 W compared to when frequency locking was not applied. Furthermore, by optimizing the temperature of the cesium cell and the reflectivity of the output coupler, we successfully achieved an output power of 1.4 W using the pump power of 2.9 W, providing a slope efficiency of 61.5% and optical-to-optical efficiency of 49%.

• 한국표면공학회지
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• 제21권1호
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• pp.47-52
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• 1988

The purpose of th this study was to determine an adsorption capaty of cesium by domestic zeolite, clinoptilolite, which has adsorption selectivity and resistence to radiolytic degradation, and to find the operation of column packed natural or Na cinoptiloite. The exchange capacity of cesium was 0, 875 m eq-per gram of clinopilolite. Na clinoptilolite was mire effective for cesium removal than naturl clioptilolite. Then, the results show that the domestic cilnoptilolite activated with sodium hydroxide colud be applicable for removal of cesium from liquid radwastes.

• 상하수도학회지
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• 제27권2호
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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.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.167-173
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• 2004

The amount of cesium released from the leaching of spent fuels in contact with and without the compacted bentonite bloc]t which was compacted as the density of $1.4g/\textrm{cm}^3$, up to 5.7 years were measured and the empirical formula of the fractional release rate of cesium were derived from these measured values. The empirical formulas show that the long-term release rate of cesium under a repository would become a constant, as about $3{\times}10_{-6}$ fraction/day, after a certain period. The cumulative fractions of cesium released from the spent fuel with bentonite and with copper and stainless steel sheets were steadily increased, but the fraction from bare fuel was rapidly increased and then sluggishly increased. However, the remained value except its gap inventory from the cumulative fraction of cesium released from bare fuel was almost very close to the others. This suggests that the initial release of cesium from bare fuel might be dependant on its gap inventory.

• 한국환경과학회지
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• 제23권9호
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• pp.1609-1618
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• 2014

In this study, as a fundamental study for the remediation of the radionuclides-contaminated soil, the adsorption of cobalt, strontium, and cesium on natural soil and kaolin were experimently investigated and adsorption characteristics were evaluated by using several adsorption kinetic and isotherm models. The pseudo-first-order kinetic model (PFOM), pseudo-second-order kinetic model (PSOM), one-site mass transfer model (OSMTM), and two compartment first-order kinetic model (TCFOKM) were used to evaluate the kinetic data and the pseudo-second-order kinetic model was the best with good correlation. The adsorption equilibria of cobalt, strontium, and cesium on natural soil were fitted successfully by Redlich-Peterson and Sips models. For kaolin, the adsorption equilibria of cobalt, strontium, and cesium were fitted well by Redlich-Peterson, Freundlich, and Sips models, respectively. The amount of adsorbed radionuclides on natural soil and kaolin was in the order of cesium > strontium > cobalt. It is considered that these results could be useful to predicting the adsorption behaviors of radionuclides such as cobalt, strontium, and cesium in soil environments.

• 자원환경지질
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• 제41권6호
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• pp.709-717
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• 2008

대표적 오염 방사능 핵종인 세슘(cesium)으로 오염된 수계를 정화하기위하여 해바라기(Sunflower; Helianthus annuus L.)와 강낭콩(Bean; Phaseolus vulgaris var.)을 이용한 뿌리여과(rhizofiltration) 실내 실험을 실시하였다. 해바라기의 경우 뿌리여 과실험 24시간 내에 세슘의 98%를 제거하였으며, 강낭콩은 99%의 제거율을 나타내어 친환경적이며 녹색 정화방법인 뿌리여과법이 세슘으로 오염된 수계 정화에 매우 효과적으로 적용 할 수 있음을 제시하였다. 수용액의 pH에 따른 뿌리여과법의 세슘 제거 실험 결과, 두 식물 모두에서 오염수의 pH가 $5{\sim}9$인 경우 98%이상의 제거효율을 나타내었다. 뿌리여과법 실험 후 식물에 농축된 세슘량을 부위별로 측정한 결과, 수용액으로부터 식물로 이동한 총 세슘의 80% 이상이 뿌리에 농축되어 있는 것으로 나타났다. 이러한 결과는 대규모 오염 현장에서 뿌리여과법을 적용 시, 농축이 심한 뿌리 부분만을 후 처리함으로써 비용과 시간을 절감할 수 있음을 의미한다. 뿌리여과법 적용 후 식물 뿌리 표면의 SEM이미지와 EDS성분 분석 결과, 수용액 내 세슘은 먼저 뿌리 표면에 이온상으로 흡착한 후 서서히 뿌리 내부로 흡수되는 것으로 판단되었다.