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JNFCWT(Journal of Nuclear Fuel Cycle and Waste Technology) - 방사성폐기물학회지
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Journal Abbreviation 'J. Nuel. Fuel Cycle Waste Technol.'
Frequencyquarterly
Doi Prefix10.7733/jnfcwt
ISSN 1738-1894 (Print)
ISSN 2288-5471 (Online)
Current Issue : 2024년 12월 / 22권 4호
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Occupational Radiation Doses to Workers Transporting Spent Nuclear Fuel by Using Metal Overpack
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저자
Shin Dong Lee, Geon Woo Son,Jeong Woo Lee,Kwang Pyo Kim
학술지JNFCWT 22권 4호 523-528p / 2024년 12월
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The transportation of spent nuclear fuel between management stages is expected, and the transportation workers may be exposed to radiation. When transporting spent nuclear fuel, the ALARA principle must be observed for the workers. The obj!ective of this study is to assess a radiation dose for workers transporting spent nuclear fuel using metal overpacks. For this obj!ective, the cask to be handled was selected and the radiation source term was set. Then, the radiation exposure scenario for the transportation workers was defined. Finally, the dose rates for each location of operation were assessed using Monte Carlo simulations, and collective doses were derived for each operation considering the radiation exposure scenario. Each worker performed 11 operations to transport spent nuclear fuel to other facilities and was exposed to a total of 1.138 man-mSv. The operation of removing the bottom shield ring resulted in the highest radiation exposure at 0.503 man-mSv. In contrast, the operation of installing the impact limiter resulted in the lowest radiation exposure at 0.0009 man-mSv. The results of this study can be used to strengthen radiation protection measures for workers transporting spent nuclear fuel in dry storage facilities using metal overpacks.
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The World Leading Deep Geological Repository Projects: A Synthetic Description of the High-Level Waste Long-Term Management Facilities Programed in Finland, Sweden, France and Switzerland and an Overview of the Deep Geological Repository Site Selection M
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저자
Pascal Claude LEVERD
학술지JNFCWT 22권 4호 503-522p / 2024년 12월
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Deep geological repositories (DGR) count amongst the world largest environmental protection projects. They are the internationally advocated reference solution for the long-term management of high-level radioactive waste (HLW) and spent nuclear fuel (SNF). Many countries have engaged in programs to develop their own DGR. In Europe, four countries have passed the important milestone of choosing or announcing the appropriate site for the location of their HLW disposal facilities. Finland has almost finished the commissioning of its DGR and should start industrial disposal operations in 2025. Sweden has authorized the construction of its DGR and is finalizing the licensing document to start construction. France is reviewing the construction license application of its DGR. Switzerland has proposed the location of its DGR and is carrying out the production of the documentation for the license application. These four countries took decades to choose the location for their DGR. The length of this process is explained by 1) the amount of technical investigations and studies that were carried out to first identify, select and then fully characterize the suitable site and 2) the progressive decision-making process defined by their respective legal frameworks, including the participation and engagement of communities and stakeholders.
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Analyses on the Thickness of the Bentonite Buffer in Deep Geological Disposal for Spent Nuclear Fuels
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저자
Jongyoul Lee, Heuijoo Choi,Changsoo Lee,Sunghoon Ji,Dongkeun Cho
학술지JNFCWT 22권 4호 491-501p / 2024년 12월
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A multi-barrier can be applied for the deep geological disposal of high-level radioactive waste. The multi-barrier comprises an engineered barrier and the natural barrier of the host rock. In the engineered barrier, the bentonite buffer is the key component for the disposal container, and the bentonite buffer thickness is given important consideration when designing the engineered barrier. This study reviewed the safety functions of bentonite buffers. Subsequently, the requirements and factors necessary to determine the thickness of the bentonite buffer, including criteria for radiological safety and the thermal stability of the disposal system, were identified. Additionally, the bentonite buffer thicknesses required for the top, bottom, and side of the disposal container were calculated. A double-layered emplacement method is also proposed for the bentonite buffer to improve disposal efficiency in terms of thermal management. Based on radiological safety and thermal stability analyses, an optimal thickness of 0.36 m was found to be appropriate for the bentonite buffer surrounding the disposal container. The thickness of the bentonite buffer above the disposal container can be determined based on the excavation damaged zone depth. The study findings can be used as a reference when designing deep geological disposal systems.
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Alteration of Bentonite in Hydrogen Sulfide-Rich Deep Borehole
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저자
Minsoo Lee, Mihye Kong,Jinseop Kim
학술지JNFCWT 22권 4호 477-489p / 2024년 12월
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We analyzed the mineral composition of compacted calcium bentonite (GJ-I) and uncompressed sodium bentonite (MX80), both of which were exposed for two years in the YS03 borehole. The YS03 borehole is characterized by a high concentration of anaerobic microorganisms, including sulfate-reducing bacteria, elevated levels of hydrogen sulfide, and high pH conditions. The compacted Ca bentonite showed minimal alteration, with a small amount of new magnetite formation. However, an X-ray diffraction (XRD) analysis revealed that the uncompressed Na bentonite underwent a complete transformation from montmorillonite to muscovite, goethite, and magnetite. Therefore, it is suspected that the compactness of the bentonite significantly impacts the rate of alteration. Furthermore, an X-ray fluorescence (XRF) analysis demonstrated a marked increase in iron oxide in the Na bentonite, whereas key elements of montmorillonite such as alumina (Al<sub>2</sub>O<sub>3</sub>), silica (SiO<sub>2</sub>), and magnesium oxide (MgO) showed substantial decreases. The presumed cause of the alteration in the uncompressed MX80 bentonite is the presence of Fe cations coupled with a high pH environment. We believe that Fe cations, which were likely released from the corrosion of cast iron, played a significant role in altering the montmorillonite lattice.
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Sensitivity Analysis for Factor of the On-link Public Assessment Model in Radioactive Waste Overland Transportation
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저자
Ga Eun Oh, Min Woo Kwak,Dong Gyu Lee,Kwang Pyo Kim
학술지JNFCWT 22권 4호 465-476p / 2024년 12월
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The increase in radioactive waste increased the demand for transportation to the disposal facility. Prior to transporting radioactive waste, confirming that the potential exposure is insignificant is crucial. Overland transportation risk assessment models were developed tailored to domestic characteristics. Dose assessment using this model requires selecting appropriate factors. However, users may struggle to derive appropriate values, leading to inaccuracies. Additionally, if assessment results show outliers, prioritizing factors for review can be challenging. Therefore, sensitivity analysis is necessary to prioritize factors for accurate assessment. In this study, sensitivity analysis was conducted on the on-link public risk assessment model factors for radioactive waste overland transportation. Initially, assessment models were analyzed by each detailed exposure scenario. Subsequently, uncertainty propagation-based sensitivity analysis methodology was applied. The default values for the assessment model factors were set, and sensitivity analysis was conducted based on road type for maximum individual and collective dose assessment models. For the maximum individual dose model, the distance to the samedirection
vehicle was the most sensitive, whereas for the collective dose model, vehicle velocity was the most sensitive. The
results of this study can be used as the basic data on radioactive waste transportation risk assessment in Korea in the future.
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Infiltration Analysis of a Multi-Layer Cover System Considering Bedrock Heterogeneity and Rainfall Variability
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저자
Soo-Gin Kim, Jae-Yeol Cheong,Chan-Hong Kim,Jeoung Seok Yoon
학술지JNFCWT 22권 4호 451-464p / 2024년 12월
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This study evaluates the long-term performance of a multi-layer cover system (MLCS) for near-surface disposal facilities using numerical modeling to estimate infiltration rates under various rainfall scenarios. An effective cover system is essential to prevent radionuclide migration and protect groundwater inflow within disposal facility. The analysis incorporated different bedrock characteristics (homogeneous and discrete fracture networks) and rainfall patterns throughout a 300-year post-closure period, assuming constant initial hydraulic properties. A comprehensive modeling approach incorporating both saturated and unsaturated flow dynamics was employed to assess system performance. Results showed that the cover system effectively limited infiltration rates to 15.94%−21.25% of the design criterion (32 mm∙year<sup>−1</sup>) across all scenarios. Although infiltration patterns showed minimal sensitivity to bedrock heterogeneity, preferential flow along fractures was observed in the unsaturated zone, necessitating further investigation. These findings emphasize the importance of considering fracture-dominated flow in cover system design and highlight the need for detailed analysis of chemical degradation effects, experimental validation, and uncertainty quantification. The study provides valuable insights for optimizing disposal facility designs and improving long-term performance assessment methodologies.
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Study on the Quench Curve for Low-Level Tritium Measurement Using a Liquid Scintillation Counter
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저자
Seongkyeong Cho, Byoung-Chul Kim,Myoung Jung Kim,Kyoung Beom Lee,Yeong Jae Park,Dong Hye Heo,Tae Hee Kim,Jong-Man Lee
학술지JNFCWT 22권 4호 441-449p / 2024년 12월
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The recent release of contaminated water from the Fukushima Daiichi Nuclear Power Plant highlights the need for accurate tritium measurement, particularly near the minimum detectable activity (MDA) of 5 Bq·L<sup>−1</sup> set by South Korea’s Nuclear Safety and Security Commission. This study aims to improve low-level tritium measurement accuracy by optimizing the region of interest (ROI) for quench curve determination. These adjustments are crucial for separating tritium signals from background noise. Quench standards were prepared and measured using a liquid scintillation counter (LSC). Three ROIs were analyzed to assess the impact of channel selection on measurement precision: A 20-148 channel range optimized via figure of merit (FOM) analysis, a 20-250 channel range covering tritium’s full beta spectrum, and a broad 1-1024 channel range. Quench curves were obtained by fitting the counting efficiency of each ROI to the quench standards. Tritium samples with six different activity levels were prepared, and their radioactivity was calculated using the quench curves. Selecting appropriate ROIs for quench curve determination is critical for measuring low-concentration tritium accurately. This approach reduces uncertainty and emphasizes reliable methods to improve the precision and consistency of tritium measurements.
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Fabrication and Characterization of Multi-Shell Structure Quantum dot Doping Organic Scintillator
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저자
Su Jung Min, Hyun Soo Kim,Heung Su Joung,Bum Kyoung Seo,Chang Hyun Roh,Sang Bum Hong
학술지JNFCWT 22권 4호 421-440p / 2024년 12월
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A scintillator using organic materials can be easily manufactured in various shapes and sizes to suit the user’s purpose. A quantum dot (QD)-based scintillator has a number of advantages over commercial scintillators, including emission wavelength control, high-purity emission of a specific wavelength, high photoluminescence efficiency, and good photostability. The organic scintillators doping with various agents into the polymer media to increase scintillation efficiency and to control the emissioning wavelength through energy transfer process. In this study, scintillator enhancement was observed with different QDs material and detection response to gamma and neutron was investigated in energy spectrum. Multishell-structure QDs (CdS/CdZnS/ZnS) were fabricated and utilized to offset the shortcomings of single-shell-structure QDs, and the optical properties and the gamma and neutron detection performance capabilities were evaluated. The results of the evaluation of the detection response of the QD-based scintillator confirmed that the neutron/gamma classification performance was similar to that of a commercial scintillator. Furthermore, the gamma detection efficiency was improved by 34–38% (in the case of <sup>137</sup>Cs) compared to a commercial scintillator. This study is especially notable in that the organic scintillator incorporated with the newly fabricated QDs can be utilized for gamma and neutron detection for the operation and decommissioning various nuclear facilities.
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Development of Training Course and Evaluation Model for Dismantling Process of Large Radioactive Components for the Application of eXtended Reality (XR)
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저자
Chang-Sig Kong, Sang-Hwa Shin,Chang-Lak Kim
학술지JNFCWT 22권 4호 411-419p / 2024년 12월
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The irradiated large components in a nuclear power plant must perform dismantling after performing a lot of training
through mockup, but this mockup training is different the realistic environment such as a high radiation environment.
Therefore, to develop a training system deployed in eXtended Reality (XR) that mimics a realistic environment, a suitable training and evaluation processes need to be developed. The target components for the training system select reactor, reactor internal and steam generator, and the training work of dismantling processes select dismantling, packaging and dismantling support work by reviewing the dismantling process of each component for XR application. By analyzing the detailed process of the selected dismantling process, Virtual Reality (VR) and Augmented Reality (AR) application processes will be developed. The basic contents of training system present purpose, goal, period, and evaluation for training and the training contents develop the basic, improvement and intensified course by level. The basic model for evaluation develop 3 stages (reaction, training, behavior) and evaluation process present detail training contents, target and evaluation method, evaluation criteria by level. Additionally, the developed training course and evaluation models will be useful for worker training in dismantling process of nuclear power plant.
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Soil Washing Technology Demonstration for Removal of Multi-Nuclides in Natural Background Soil
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저자
Choong Sup Byun, Suin Lee,Jihyun Kang,Wonseok Park,Dohyung Kim,Jongyoul Lee
학술지JNFCWT 22권 4호 399-410p / 2024년 12월
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Industries that use or produce radionuclides have unintentionally released these substances into surrounding soils and sediments. To address this problem, Beautiful Environmental Construction (BEC) Co. developed the BEC’s Radioactive Soil Decontamination (BERAD) system to remove contaminants and reduce the volume of radionuclide-contaminated soils. Owing to the limited availability of radioactive isotopes such as <sup>60</sup>Co, <sup>90</sup>Sr, <sup>137</sup>Cs, and uranium-contaminated soil, naturally occurring elements in soil were used in this demonstration. The soil was divided into six size fractions via manual wet sieving and the BERAD system. Then, the concentrations of uranium, cobalt, strontium, cesium, and iron in each fraction were measured. The results of both separations showed that a considerable amount of each element is retained in the finer size fractions (<0.2 mm). After BERAD separation, the corresponding values yielded 53% uranium, 45% strontium, 66% cobalt, and 53% cesium in the fine size (<0.2 mm) fractions of 35% by weight. The study found that the concentrations of these elements increased as the particle sizes decreased. Iron and micaceous minerals played a significant role in retaining the elements. The pilot scale BERAD system yielded results that were similar to those obtained via laboratory wet-sieving and was successfully demonstrated as a soil washing technology.
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Comparative Tolerance of Legume Species at Seed Germination and Initial Seedling Growth to Cesium (137Cs) in Electric Arc Furnace Dust Leaching Effluent
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저자
Thunyaras Akharawutchayanon, Phitthaya Nookongbut,Witsanu Katekaew,Nikom Prasertchiewchan,Vichai Puripunyavanich,Lamai Maikaeo
학술지JNFCWT 22권 4호 387-397p / 2024년 12월
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Increasing resource use is the primary motivator for the development of technology industries, which is leading to severe consequences, such as the release and disposal of radioactive waste containing radionuclides in the environment. Cesium (<sup>137</sup>Cs) is one of the most hazardous radionuclides in the environment. In particular, the steel manufacturing process produces hazardous waste in the form of electric arc furnace dust contaminated with <sup>137</sup>Cs. In this study, the tolerances of five legume species to different activity concentrations of <sup>137</sup>Cs in both seed germination and initial seedling growth were compared.
To determine <sup>137</sup>Cs tolerance, several parameters related to the growth and development of legumes were measured. Among the five legumes studied, Crotalaria juncea L. was the most <sup>137</sup>Cs tolerant at 50,000 Bq·L<sup>−1</sup>. Sesbania javanica Miq. and Vigna mungo L. Hepper were moderately tolerant to 30,000 Bq·L<sup>−1</sup> <sup>137</sup>Cs. After 10 days, the stress tolerance indices in all legume species decreased by more than 50% at activity concentrations greater than or equal to 20,000 Bq·L<sup>−1</sup> <sup>137</sup>Cs. This
approach allows the selection of desirable traits, making more-effective application possible in the phytoremediation of <sup>137</sup>Cs through stress tolerance. In conclusion, legumes are promising candidates for the phytoremediation of environmental pollutants.