• Nuclear Engineering and Technology
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• 제46권1호
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• pp.93-100
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• 2014

The paper deals with the application of radio isotopic non-destructive technique in the characterization of two industrial grade anion exchange resins Indion GS-300 and Indion-860. For the characterization of the two resins, $^{131}I$ and $^{82}Br$ were used as tracer isotopes to trace the kinetics of iodide and bromide ion-isotopic exchange reactions. It was observed that the values of specific reaction rate ($min^{-1}$), amount of iodide ion exchanged (mmol), initial rate of iodide ion exchange (mmol/min) and log $K_d$ were calculated as 0.328, 0.577, 0.189 and 19.7 respectively for Indion GS-300 resin, which was higher than the respective values of 0.180, 0.386, 0.070 and 17.0 calculated for Indion-860 resins when measured under identical experimental conditions. Also at a constant temperature of $40.0^{\circ}C$, as the concentration of labeled iodide ion solution increases 0.001 M to 0.004 M, the percentage of iodide ions exchanged increases from 75.16 % to 78.36 % for Indion GS-300 resins, which was higher than the increases from 49.65 % to 52.36 % compared to that obtained for Indion-860 resins. The overall results indicate that under identical experimental conditions, Indion GS-300 resins show superior performance over Indion-860 resins.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.379-379
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• 2018

MXenes are a new family of 2D transition metal carbide nanosheets analogous to graphene (Lv et al., 2017; Sun et al., 2018). Due to the easy availability, hydrophilic behavior, and tunable chemistry of MXenes, their use in applications for environmental pollution remediation such as heavy metal adsorption has recently been explored (Li et al., 2017). In this study, three-dimensional (3D) MXene ($Ti_3C_2T_x$) films with high adsorption capacity, good mechanical strength, and high selectivity for specific radionuclide from aquose solution were successfully fabricated by a polymeric precursor method using vacuum-assisted filtration. The highest removal efficiency on the films was 99.54%, 95.61%, and 82.79% for $Sr^{2+}$, $Co^{2+}$, and $Cs^+$, respectively, using a film dosage of 0.06 g/ L in the initial radionuclide solution (each radionuclide concentration = 1 mg/L and pH = 7.0). Especially, the adsorption process reached an equilibrium within 30 min. The expanded interlayer spacing of $Ti_3C_2T_x$ sheets in MXene films showed excellent radionuclide selectivity ($Cs^+$ and/or $Sr^{2+}/Co^{2+}$) (Simon, 2017). Besides, the MXene films was not only able to be easily retrieved from an aqueous solution by filtration after decontamination processes, but also to selectively separate desired target radionuclides in the solutions. Therefore, the newly developed MXene ($Ti_3C_2T_x$) films has a great potential for radionuclide removal from aqueous solution.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.689-695
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• 2003

Electrochemical decontamination process has been applied for recycle or self disposal with authorization of large amount of metallic wastes contaminated with uranium compounds such as $UO_2$, ammonium uranyl carbonate (AUC), ammonium di-uranate (ADU), and uranyl nitrate(UN) with tributylphosphate(TBP) and dodecane, which are generated by dismantling the contaminated system components and equipment of a retired uranium conversion plant in Korea Atomic Energy Research Institute (KAERI). Electrochemical decontamination for metallic wastes contaminated with uranium compounds was evaluated through the experiments on the electrolytic dissolution of stainless steel as the material of the system components in neutral salt electrolytes. The effects of type of neutral salt as the electrolyte, current density, and concentration of electrolyte on the dissolution of the materials were evaluated. Decontamination performance tests using the specimens taken from a uranium conversion plant were quite successful with the application electrochemical decontamination conditions obtained through the basic studies on the electrolytic dissolution of structural material of the system components.

• 한국환경과학회지
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• 제33권9호
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• pp.675-685
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• 2024

This study aimed to analyze the effects of cesium (Cs) treatment concentrations and organic matter on the growth of Chinese cabbage plants. The growth responses of cabbage to the Cs treatment varied depending on the concentration of Cs and the organic matter content in the soil. Higher concentrations of Cs in the soil presented a detrimental effect on cabbage growth. Specifically, increased Cs levels led to a reduction in leaf number, leaf area, chlorophyll content, and fresh and dry weights. However, an increase in the soil organic matter content positively affected the fresh and dry weights. These trends were particularly pronounced in Chinese cabbage plants grown for 80 days after treatment. Soil organic matter proved to effectively mitigate the negative effects of Cs on plant growth. Incorporating organic matter into Cs-contaminated soils can, therefore, enhance the immobilization of radioactive isotopes and contribute to the stabilization of contaminated soils, making it a useful strategy for managing radioactive contamination.

• 한국환경과학회지
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• 제24권3호
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• pp.275-280
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• 2015

In order to measure the Radionuclides and Concentration, the directly grinded land samples (river soil, pine leaves and mugwort) among the environment samples around the nuclear power plant were filled in a 450 mL Marinelli beaker and weighed to obtain the dry mass ratio of the samples. Then the background and land samples were measured for 80,000 sec. The analysis of the collected land samples showed that most of them contained less radiation nuclide than the detection minimum limit in the 'Ministry of Education, Science and Technology Public Notice No. 2010-32.'In others, the natural radionuclides $^{40}K$ were detected. Of the products of nuclear reaction discharged by a nuclear reaction, $^{134}Cs$ and $^{137}Cs$ are more easily detected, and their discharge sources can be traced using the relative ratio. Although the radioactive concentration in the vicinity of Kori Nuclear Power Plant, which is more than 1,100km away from Fukushima, the Japanese nuclear accident site, continuous monitoring is needed as the radionuclides can still be accumulated in the soil or animals and plants.

• Nuclear Engineering and Technology
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• 제50권5호
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• pp.806-813
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• 2018

$^{222}Rn$ exists in nature in the form of a rare radioactive gas. In terms of environmental radiation, issues regarding $^{222}Rn$ have persisted because of its radiological hazardousness. Ulju County is one of the regions of Ulsan metropolitan city, with a population of 227,699. Ulju County has the highest density of industrial complexes in Korea. In this study, $^{222}Rn$ radioactivity concentration was measured and analyzed in 57 schools in Ulju County using 114 passive LR-115 type detectors to secure radiological safety and confirm basic information for reduction of resident exposure to $^{222}Rn$. The effective dose of $^{222}Rn$ was assessed to find the actual risk of the concentration surveyed in schools to human beings. The dose depended on four factors: subjects, $^{222}Rn$ concentration, dose coefficient, and time. The individuals subjected to dose estimation were classified into three types: students, teachers, and office workers. The subjects had different dwelling locations and times. The findings demonstrate that the radiological hazard to students and workers at schools in Ulju County owing to $^{222}Rn$ is negligible in terms of $^{222}Rn$ activity recommendation level.

• 방사성폐기물학회지
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• 제21권1호
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• pp.43-53
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• 2023

Sulfide concentrations critically affect worker safety and the integrities of underground facilities, such as deep geological repositories for spent nuclear fuel. Sulfide is highly sensitive to oxygen, which can oxidize sulfide to sulfate. This can hinder precise measurement of the sulfide concentration. Hence, a literature review was conducted, which revealed that two methods are commonly used: the methylene blue and sulfide ion-selective electrode (ISE) methods. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used for comparison with the two methods. The sulfide ISE method was found to be superior as it yielded results with a higher degree of accuracy and involved fewer procedures for quantification of the sulfide concentration in solution. ICP-OES results can be distorted significantly when sulfide is present in solution owing to the formation of H₂S gas in the ICP-OES nebulizer. Therefore, the ICP-OES must be used with caution when quantifying underground water to prevent any distortion in the measured results. The results also suggest important measures to avoid problems when using ICP-OES for site selection. Furthermore, the sulfide ISE method is useful in determining sulfide concentrations in the field to predict the lifetime of disposal canisters of spent nuclear fuel in deep geological repositories and other industries.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1225-1232
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• 2023

The ¹⁸⁰W is the lightest isotope of Tungsten with small abundance ratio. It is slightly radioactive (α decay), with an extremely long half-life. Its separation is possible by non-conventional single withdrawal cascades. The ¹⁸⁰W is used in radioisotopes production and study of metals through gamma-ray spectroscopy. In this paper, single withdrawal cascade model is developed to evaluate multicomponent separation in non-conventional transient cascades, and available experimental results are used for validation. Numerical studies for separation of ¹⁸⁰W in a transient single withdrawal cascade are performed. Parameters affecting the separation and equilibrium time of cascade such as number of stages, cascade arrangements, feed location and flow rate for a fixed number of gas centrifuges (GC) are investigated. The Salp Swarm Algorithm (SSA) as a bio-inspired optimization algorithm is applied as a novel method to minimize the feed consumption to obtain desired concentration in the collection tank. Examining different cascade arrangements, it is observed in arrangements with more stages, the separation is further efficient. Based on the obtained results, with increasing feed flow rate, for fixed product concentration, the cascade equilibrium time decreases. Also, it is shown while the feed location is the farthest stage from the collection tank, the separation and cascade equilibrium time are well-organized. Finally, using SSA optimal parameters of the cascade is calculated, and optimal arrangement to produce 5 gr of ¹⁸⁰W with 90% concentration in the tank, is proposed.

• 방사성폐기물학회지
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• 제8권3호
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• pp.215-220
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• 2010

수중 지표동물인 어류의 $^{137}Cs$ 및 $^{85}Sr$ 전이계수 측정 실험이 수행되었다. 실험 어종은 우리나라 고유 담수종인 버들치(Chinese Minnow, Rhynchocypris Oxycephalus)였다. 버들치는 가로, 세로, 높이가 각각 45cm, 85cm, 50cm의 아크릴 수족관 내에서 사육되었다. 수족관 물은 바닥과 벽면에 설치된 여과기에 의해 연속적으로 정화되었다. 먹이로는 과립 형태의 어류 분말을 1일 2회 투여하였다. 수중 $^{137}Cs$ 과 $^{85}Sr$의 초기 농도가 각각 약 $0.02{\mu}Ci/l$ 및 $0.1{\mu}Ci/l$가 되도록 방사성 용액을 가한 다음 1개월 간 총 10회에 걸쳐 어류와 물 시료를 채취하였다. 전이계수는 $^{137}Cs$ 이 $(0.085\sim3.988)lkg^{-1}$, $^{85}Sr$는 $(0.348\sim13.906)lkg^{-1}$로 측정되었다.

• 한국가축번식학회지
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• 제9권2호
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• pp.133-139
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• 1985

An immunoassay may be defined as an analytical procedure involving the competitive reaction between a limiting concentration of specific antibody and two populations of antigen, one of which is labelled or immobillized. The advent of immunoassay has revolutionised our knowledge of reproductive physiology and the practice of veterinary and clinical medicine. Radioimmunoassay (RIA) was the first of these methods to be developed, which meausred the analyte with good sensitivity, accuracy and precision (1,2). The essential components of RIA are:-(i) a limited concentration of antibodies, (ii) a reference preparation, and (iii) an antigen labelled with a radioisotope (usually tritium or iodine-125). Most procedures invelove isolating the antibody-bound fraction and measuring the amount of labelled antigen. Good facilities are available for scintilltion counting, data reduction nd statistical analysis. RIA is undergoing refinement through:-(i) the introduction of new techniques to separate the antibody-bound and free fractions which minimize the misclassification of labelled antigen into these compartments, and the amount of non-specfic binding. (3), (ii) the development of non-extration for the measurement of haptens (4), (iii) the determination of a, pp.rent free (i.e. non-protein bound) analytes (5), and (iv) the use of monoclonal antibodies(6). In 1968, Miles and Hales introduced in important new type of immunoassay which they termed immunora-diometric assay (IRMA) based on t도 use of isotopically labelled specific antibodies(7) in a move from limited to excess reagent systems. The concept of two-site IRMAs (with a capture antibody on a solid-phase, and a second labelled antibody to a different antigenic determinant of the analyte) has enabled the development of more sensitive and less-time consuming methods for the measurement of protein hormones ovar wide concentration of analyte (8). The increasing use of isotopic methos for diverse a, pp.ications has exposed several problems. For example, the radioactive half-life and radiolysis of the labelled reagent limits assay sensitivity and imposes a time limit on the usefulness of a kit. In addition, the potential health hazards associated with the use and disposal of radioactive cmpounds and the solvents and photofluors necessary for liquid scientillation counting are incompatable with the development of extra-laboratory tests. To date, the most practical alternative labels to radioisotopes, for the measurement of analytes in a concentration > 1 ng/ml, are erythrocytes, polystyrene particiles, gold sols, dyes and enzymes or cofactors with a visual or colorimetric end-point(9). Increased sensitivity to<1 pg/ml may be obtained with fluorescent and chemiluminescent labels, or enzymes with a fluorometric, chemiluminometric or bioluminometric end-point. The sensitivity of any immunoassay or immunometric assay depends on the affinity of the antibody-antigen reaction, the specific activity of the label, the precision with which the reagents are manipulated and the nonspecific background signal (10). The sensitivity of a limited reagent system for the measurement of haptens or proteins is mainly dependent upon the affinity of the antibodies and the smalleest amount of reagent that may be manipulated. Consequently, it is difficult in practice to improve on the sensitivity obtained with iodine-125 as the label. Conversely, with excess reagent systems for the measurement of proteins it is theoretically possible to increase assay sensitivity at least 1000 fold with alternative luminescent labels. To date, a 10-fold improvement has been achieved, and attempts are being made to reduce the influence of other variables on the specific signal from the immunoreaction.