The bentonite buffer material is a crucial component in an engineered barrier system used for the disposal of high-level radioactive waste. Because a large amount of heat from the disposal canister is released into the bentonite buffer material, the thermal conductivity of the bentonite buffer is a crucial parameter that determines the design temperature. At the Korea Atomic Energy Research Institute (KAERI), a new standard bentonite (Bentonil-WRK) has been used since 2022 because Gyeongju (KJ) bentonite is no longer produced. However, the currently available data are insufficient, making it essential to investigate both the basic and complex properties of Bentonil-WRK. Thus, this study evaluated its geotechnical and thermal properties and developed a thermal conductivity empirical model that considers its dry density, water content, and temperature variations from room temperature to 90°C. The coefficient of determination (R2) for the model was found to be 0.986. The thermal conductivity values of Bentonil-WRK were 1–10% lower than those of KJ bentonite and 10–40% higher than those of MX-80 bentonites, which were attributable to mineral-composition differences. The thermal conductivity of Bentonil-WRK ranged between 0.504 and 1.149 W·(m−1·K−1), while the specific heat capacity varied from 0.826 to 1.138 (kJ·(kg−1·K−1)).

Effects of glutamic acid (Glu) and monosodium glutamate (MSG) on oxidative stability of oil-in-water (O/W) emulsions with different emulsifier charges during riboflavin (RF) photosensitization were evaluated by analyzing headspace oxygen content and conjugated dienes. Cetyltrimethylammonium bromide (CTAB), Tween 20, and sodium dodecyl sulfate (SDS) were used as cationic, neutral, and anionic emulsifiers, respectively. Glu acted as an antioxidant in CTAB- and Tween-20-stabilized O/W emulsions during RF sensitization, whereas Glu acted as prooxidants in SDS-stabilized O/W emulsions in the dark. However, adding MSG did not have a constant impact on the degree of oxidation in O/W emulsions irrespective of the emulsifier charge. In RF-photosensitized O/W emulsions, the emulsifier charge had a greater influence on antioxidant properties of Glu than on those of MSG.

A force-free field (FFF) is determined solely by the normal components of magnetic field and current density on the entire boundary of the domain. Methods employing three components of magnetic field suffer from overspecification of boundary conditions and/or a nonzero divergence-B problem. A vector potential formulation eliminates the latter issue, but introduces difficulties in imposing the normal component of current density at the boundary. This paper proposes four different boundary treatment methods within the vector potential formulation. We conduct a comparative analysis of the vector potential FFF solvers that we have developed incorporating these methods against other FFF codes in different magnetic field representations. Although the vector potential solvers with the new boundary treatments do not outperform our poloidal-toroidal formulation code, they demonstrate comparable or superior performance compared to the optimization code in SolarSoftWare. The methods developed here are expected to be readily applied not only to force-free field computations but also to time-dependent data-driven simulations.

Hypertension is characterized by excessive renin-angiotensin system activity, leading to blood vessel constriction. Several synthetic compounds have been developed to inhibit renin and angiotensin-converting enzyme (ACE). These drugs often have adverse side effects, driving the exploration of plant protein-derived peptides as alternative or supplementary treatments. This study assessed the phenolic compound and amino acid content and the antioxidant and antihypertensive activity of 5 South Korean staple crops. Sorghum had the highest phenolic compound content and exhibited the highest antioxidant activity. Millet grains, particularly finger millet (38.86%), showed higher antihypertensive activity than red beans (14.42%) and sorghum (17.16%). Finger millet was found to contain a large proportion of branched-chain, aromatic, and sulfur-containing amino acids, which are associated with ACE inhibition. In particular, cysteine content was positively correlated with ACE inhibition in the crops tested (r=0.696, p<0.01). This study confirmed that the amino acid composition was more correlated with the antihypertensive activity of grains than the phenolic compound content. Finger millet mainly contained amino acids, which have higher ACE inhibitory activity, resulting in the strongest antihypertensive activity. These findings underscore the antihypertensive potential of select crops as plant-based food ingredients, offering insight into their biological functions.

본 연구는 온라인 절화 도매 플랫폼에 대한 이용자 인식, 이용 현황을 알아보고, 본 플랫폼의 발전 방향을 제시하기 위 하여 국내 화훼 장식 종사자 300명을 대상으로 조사 연구하 였다. 연구 결과 화훼 장식 종사자의 99%가 온라인 절화 도매 플랫폼에 대해 인지하고 있었으며, 실제 이용 경험 역시 68% 로 높게 나타났다. 이용자들의 서비스 이용 기간은 1~2년이 46.5%로 가장 많았으며 월평균 구매 횟수는 6~15회가 과반 을 차지하였고, 온라인 절화 도매 플랫폼의 1회 기준 소비 금 액은 15만 원 미만이 62.4%로 나타났으나, 오프라인 절화 도 매시장의 사용 빈도 및 소비 금액이 더 높은 것으로 나타났다 (p<0.001). 화훼 장식 종사자들은 절화의 품질(4.85) 및 상품 의 다양성(4.75)이 절화 구매 시 가장 중요한 고려 요인이었 으며, 온라인 절화 도매 플랫폼에서의 상품 구매 시 과거 구매 경험(3.97)과 상품의 사진(3.87)을 보고 절화 품질을 판단하 는 경우가 가장 많았다. 온라인 절화 도매 플랫폼의 가장 큰 장점으로는 시간을 절약(4.39)할 수 있다는 점으로 인식하고 있었으나, 상품 구매 시 불안 요인으로는 절화 신선도(4.30)와 품질(4.02)에 대한 우려가 높은 것으로 나타났다. 온라인 절화 도매 플랫폼에서 제공하는 서비스 품질에 대해 이용자들은 주 문한 상품과 배송 상품이 일치(4.19)하며, 사용하기 쉬운 페이 지로 구성(4.03)되어 있어 구매 과정(4.00)이 편리하다고 응 답하였으나, 상품 품질에 대한 만족도는 모두 보통 이하로 낮 게 나타났다. 온라인 절화 도매 플랫폼과 오프라인 절화 도매 시장에서의 절화 구매 후 만족도를 비교한 결과 온라인 절화 도매 플랫폼에서는 가격과 반품 처리에 있어 오프라인에 비해 강점을 가지고 있었으나, 가장 중요한 절화 구매 결정 요인인 절화 신선도와 상품 다양성에 있어서 오프라인 절화 도매시장 에 비해 부족함을 보였다. 결론적으로 온라인 절화 도매 플랫 폼의 발전을 위해서는 절화 상품 품질 향상 및 다양성 확보가 필요하며 국내 화훼산업의 지속적인 발전과 성장을 위하여 새 로운 화훼 시장 형태에 대한 다양한 추가 연구가 필요할 것으 로 판단된다.

When the parent radionuclide decays, the progeny radionuclide is produced. Accordingly, the dose contribution of the progeny radionuclide should be considered when assessing dose. For this purpose, European Commission (EC) and International Atomic Energy Agency (IAEA) provide weighting factors for dose coefficient. However, these weighting factors have a limitation that does not reflect the latest nuclide data. Therefore, in this study, we analyzed the EC and IAEA methodology for derivation of weighting factor and used the latest nuclide data from ICRP 107 to derive weighting factors for dose coefficient. Weighting factor calculation is carried out through 1) selection of nuclide, 2) setting of evaluation period, and 3) derivation based on ICRP 107 radionuclide data. Firstly, in order to derive the weighting factor, we need to select the radionuclides whose dose contribution should be considered. If the half-life of progeny radionuclides sufficiently short compared to the parent radionuclide to achieve radioactive equilibrium, or if the dose coefficient is greater of similar to that of the parent radionuclide and cannot be ignored, the dose contribution of the progeny radionuclide should be considered. In order not to underestimate the dose contribution of progeny radionuclides, the weighting factors for the progeny nuclides are taken as the maximum activity ratio that the respective progeny radionuclides will reach during a time span of 100 years. Finally, the weighting factor can be derived by considering the radioactivity ratio and branch fraction. In order to calculate the weighting factor, decay data such as the half-life of the radionuclide, decay chain, and branch fraction are required. In this study, radionuclide data from ICRP 107 was used. As a result of the evaluation, for most radionuclides, the weighting factors were derived similarly to the existing EC and IAEA weighting factors. However, for some nuclides, the weighting factors were significantly different from EC and IAEA. This is judged to be a difference in the half-life and branch fraction of the radionuclide. For example, in the case of 95Zr, the weighting factor for 95mNb showed a 35.8% difference between this study and previous study. For ICRP 38, when 95Zr decays, the branch fraction for 95mNb is 6.98×10-3. In contrast, for ICRP 107, the branch fraction is 1.08×10-2, a difference of 54.7%. Therefore, the weighting factor for the dose coefficient based on ICRP 107 data may differ from existing studies depending on the half-life and decay information of the nuclide. This suggests the need for a weighting factor based on the latest nuclide data. The results of this study can be used as a basis for the consideration of dose contributions for progeny radionuclides in various dose assessments.

The demand for transportation is increasing due to the continuous generation of radioactive wastes. Especially, considering the geographical characteristics of Korea and the location characteristics of nuclear facilities, the demand for maritime transportation is expected to increase. If a sinking accident happens during maritime transportation, radioactive materials can be released into the ocean from radioactive waste transportation containers. Radioactive materials can spread through the ocean currents and have radiological effects on humans. The effect on humans is proportional to the concentration of radioactive materials in the ocean compartment. In order to calculate the concentration of radioactive materials that constantly flow along the ocean current, it is necessary to divide the wide ocean into appropriate compartments and express the transfer processes of radioactive materials between the compartments. Accordingly, this study analyzed various ocean transfer evaluation methodologies of overseas maritime transportation risk codes. MARINRAD, POSEIDON, and LAMER codes were selected to analyze the maritime transfer evaluation methodology. MARINRAD divided the ocean into two types of compartments that water and sediment compartments. And it was assumed that radionuclides are transfered from water to water or from water to sediment. Advection, diffusion, and sedimentation were established as transfer process for radionuclides between compartments. MARINRAD use transfer parameters to evaluate transer processes by advection, diffusion, and sedimentation. Transfer parameters were affected by flow rate, sedimentation rate, sediment porosity, and etc. POSEIDON also divided the ocean into two types that water and sediment compartment, each compartments was detaily divided into three vertical sub-compartment. Advection, diffusion, resuspension, sedimentation, and bioturbation were established as transport processes for radionuclides between compartments. POSEIDON also used transfer parameters for evaluating advection, diffusion, resuspension, sedimentation, and bioturbation. Transfer parameters were affected by suspended sediment rates, sedimentation rates, vertical diffusion coefficients, bioturbation factors, porosity, and etc. LAMER only considered the water compartment. It divided the water compartment into vertical detailed compartments. Diffusion, advection and sedimentation were established as the nuclide transfer processes between the compartments. To evaluated the transfer processes of nuclides for diffusion and advection, LAMER calculated the probability with generating random position vectors for radionuclides’ locations rather than deterministic methods such as MARINRAD’s transfer parameters or POSEIDON’s transfer rates to evaluate transfer processes. The results of this study can be used as a basis for developing radioactive materials’ ocean transfer evaluation model.

Wolsong Unit 1 nuclear power plant, which was permanently shut down in 2019, has a 678 MWe calandria vessel of the CANDU-6 type pressurized heavy-water reactor model. The calandria inside the vault is a horizontal cylindrical vessel made of stainless steel with a length of 7.8 m and a thickness of 28.6 mm. For the entire dismantling processes of a nuclear power plant, dismantling works cannot be performed using only one cutting technology and method, and when performing dismantling of a calandria vessel, various systems and components can be used for cutting and dismantling. The calandria vessel is located in a concrete compartment called a vault, and in order to safely dismantle the calandria vessel, the spread of radioactive contaminants from inside of the vault to the outside must be prevented. We designed dismantling processes using the laser cutting method to dismantle the calandria vessel and end shields. We must minimize the risk of internal radiation exposure to workers from aerosols derived from the thermal cutting processes. Therefore, we need a way to prevent secondary contamination from spreading outside the vault and within the reactor building. The path through which radioactive contaminants move is that the flying airborne products generated during the cutting process inside the vault where the calandria is located do not stay in place but spread outward through the opening of the RM-Deck structure at the top. Therefore, facilities or devices are needed to effectively prevent the spread of radioactive contaminants by blocking the expected movement path. By using these facilities or devices, it is possible to prevent the movement of radioactive aerosol particles between the location of the worker and the location of the cutting area where the calandria is located, thereby preventing internal exposure through the worker’s breathing. In addition, by using these, the cutting area where airborne pollutants are generated can be designed as an isolated work space to prevent the spread of radioactive contaminants. In this study, we propose a method of facilities for confining radioactive aerosol particles and preventing the spread of contamination when thermal cutting of the calandria vessel within the vault.

As unit 1 of Kori was permanently shut down in June 2017, domestic nuclear industry has entered the path of decommissioning. The most important thing in decommissioning is cost reduction. And volume reduction of radioactive waste is especially important. According to the IAEA report, more than 4,000 tons of metallic waste is generated during the decommissioning of a 1,000 MWe reactor and most of these wastes are LLW or VLLW. To reduce amount of metallic waste dramatically, we should choose efficient decontamination method. In this study, we conducted dry ice and bead blasting decontamination. We prepared Inconel-600 and STS-304 specimen with dimensions of 30 mm × 30 mm × 5 mm. Loose and fixed contamination was applied on the surface of specimen using SIMCON method. Bead and dry-ice blasting was conducted by spraying alumina and dry ice pellet at the same pressure and distance for the same time. The removal of loose contamination was observed using microscope. It was found that contaminants are significantly removed using both dry ice blasting and bead blasting. However, some abrasive material remained on the surface of specimen. The removal of fixed contamination was verified by weight comparison before and after experiment and cobalt concentration comparison before and after experiment using X-ray Fluorescence Spectroscope (XRF). At least 90% of the cobalt was removed, but some abrasive particle was also remained on the surface of specimen. In this study, it is confirmed that the effectiveness of manufacturing a large-scale abrasive decontamination facility, and it is expected that this technology can be used to effectively reduce the amount of metallic waste generated during decommissioning.

The post-closure safety assessment of a repository is typically conducted over an extensive timescale from ten thousand to a million years. Considering that biosphere ecosystems may undergo significant changes over such lengthy periods, it is essential to incorporate the long-term evolution of the biosphere into the safety assessment. Climate change and landscape development are identified as critical drivers with the potential to impact the hydrogeological and hydrogeochemical characteristics of the biosphere. These changes can subsequently alter the migration patterns of radionuclides through the biosphere and influence human exposure doses. Therefore, this study formulates scenarios within the context of long-term biosphere evolution. We examine biosphere assessment processes employed in other countries and conduct a comparative study on scenario conditions. For example, biosphere assessment in Finland has identified sea-level changes and land-use alterations as significant factors in the long-term evolution of the biosphere. These factors are linked to Features, Events, and Processes (FEPs) associated with climate change and human activities. Sea-level changes are related to FEPs regarding climate change, land uplift, and shoreline displacement, while land-use changes are based on human activity-related FEPs (e.g., crop type, livestock and forest management, well construction, and demographics). Based on the literature review, this study has configured long-term evolution scenarios for the safety assessment of a deep geological repository for spent fuels.

Safety assessments for geological disposal systems extend over tens of thousands of years, taking into account the radiotoxicity decay period of spent nuclear fuel. During this extensive period, the biosphere experiences multiple glacial cycles, and fluctuations in seawater amounts, attributed to the formation and melting of glaciers, lead to global sea level changes known as eustacy. These sea level changes can directly influence the land-sea interface and groundwater flow dynamics, consequently affecting the pathways of radionuclide transport - an essential element of dose assessment. Therefore, this study aims to investigate how glacial cycles and sea level changes impact radionuclide transport within geological disposal systems, especially in the biosphere. To achieve this objective, we obtained climate evolution data including sea level changes for the Korean Peninsula over a 200,000-years, simulated by a General Circulation Model (GCM). These data were then employed to predict site and hydrology evolutions. The study site was conceptualized biosphere of Artificial Disposal System (ADioS), and we utilized the Soil and Water Assessment Tool (SWAT) to simulate hydrological evolution. These datasets, encompassing climate, site, and hydrology evolution, were collectively employed as inputs for the biosphere module of Adaptive Process-Based Total System Performance Assessment Framework (APro). Subsequently, the APro’s biosphere module calculated radionuclide transport in groundwater flow and its release into surface water bodies, considering the influences of glacial cycles and sea level changes. The results show that hydrologic changes due to sea level change are relatively minor, while the impact of sea level change on groundwater flow and discharge is significant. Additionally, we identified that among the water bodies within ADioS, including rivers, lakes, and oceans, the ocean exhibits the most substantial radionuclide outflow throughout the entire period. The spatiotemporal distributions of radionuclides computed within APro will be further processed into a grid format and used as input for the dose assessment module. Through this study, it was possible to determine the impact of long-term glacial cycles and sea level changes on radionuclide transport. Additionally, this module can serve as a valuable tool for providing the spatiotemporal variability of radionuclides required for enhanced dose assessments.

Engineered Barrier Systems (EBS) are a key element of deep geological repositories (DGR) and play an important role in safely isolating radioactive materials from the ecosystem. In the environment of a DGR, gases can be generated due to several factors, including canister corrosion. If the gas production rate exceeds the diffusion rate, pore pressures may increase, potentially inducing structural deterioration that impairs the function of the buffer material. Therefore, understanding the hydraulic-mechanical behavior of EBS due to gas generation is essential for evaluating the longterm stability of DGR. This study employed X-ray computed tomography (CT) technology to observe cracks created inside the buffer material after laboratory-scale gas injection experiments. After CT scanning, we identified cracks more clearly using an image analysis method based on machine learning techniques, enabling us to examine internal crack patterns caused by gas injection. In the samples observed in this study, no cracks were observed penetrating the entire buffer block, and it was confirmed that most cracks were created through the radial surface of the block. This is similar to the results observed in the LASGIT field experiment in which the paths of the gas migration were observed through the interface between the container and the buffer material. This study confirmed the applicability of high-resolution X-ray CT imaging and image analysis techniques for qualitative analysis of internal crack patterns and cracks generated by gas breakthrough phenomena. This is expected to be used as basic data and crack analysis techniques in future research to understand gas migration in the buffer material.

The Korea Atomic Energy Research Institute (KAERI) is currently developing a process-based performance assessment model known as APro. Distinguished from the previous system-level safety assessment model developed by KAERI, APro exhibits the capacity to encompass a threedimensional biosphere domain, evolving over the long term. In this study, we elucidate the methodology employed in developing the dose assessment module of APro and present the module’s functionalities. The procedural steps underlying radiation dose calculations within the APro framework can be succinctly outlined as follows: 1) Definition of a landscape model, utilizing information derived from a specified snapshot period provided by the APro biosphere transport module; 2) Generation of unit biotope objects spanning the landscape; 3) Evaluation of radionuclide transfer within the soil medium; 4) Calculation of activity concentration for flora and fauna groups; 5) Assessment of the distribution of effective dose among representative human groups; 6) Progressing through successive time steps. The APro dose calculation module exhibits notable capabilities that encompass: 1) Accounting for radionuclide decay and ingrowth; 2) Facilitating transfer through unsaturated porous media; 3) Considering sorption effects; 4) Addressing the inheritance of radioactivity between various landscape models; 5) Offering customizable ecosystem parameters; 6) Providing flexibility for user-defined exposure pathways. Leveraging these functionalities of the dose assessment module, APro is proficient in evaluating the distribution of radiological doses and associated risks for representative population groups, all while accounting for the dynamic, long-term evolution of the biosphere, including alterations in land cover.