This study investigates the behavior of the thermal conductivity among material properties in order to develop a thermal evaluation methodology of spent fuel assembles in a transport cask. It is inefficient to model each element of the spent fuel assembly in detail, and it is generally calculated by modeling the effective thermal conductivity (ETC). The ETC model was developed to allow a much simpler representation of a spent fuel assembly within a fuel compartment by treating the entire spent fuel rod array and the surrounding fill gas within the confines of the compartment as a homogenous solid material. The fuel rod assembly and surrounding gas are modeled with an effective conductivity that is designed to yield an overall conduction heat transfer rate that is equivalent to the combined effect of local conduction and radiation heat transfer in a plane through the assembly. When this model is applied to the transport cask, it tends to predict the cladding peak temperature lower than the results of detailed model in which the fuel rod arrangement and shape of the fuel assembly are simulated. As for the tendency of the error, the model tended to under-predict when basket temperature was lower than a certain temperature, and over-predict when it was higher. The purpose of this study is to investigate the attenuation effect of the cladding peak temperature on the related variables when the ETC model is applied to the transport cask. In addition, based on the thermal characteristics of this model, a correction factor that can compensate for this attenuation effect is presented. This correction factor is obtained by finding the difference between a separate ETC homogeneous model and a separate detailed fuel model, rather than directly applying the ETC calculated from the detailed fuel model to the transport cask.

Spent nuclear fuels released from the reactor are stored in cooling pools and then stored in dry storage casks. During the transition from the wet storage to dry storage cask, a vacuum drying process is used to remove residual water in the cask. During the vacuum drying process, gas pressure is reduced to below 400 Pa to promote evaporation and water removal. KAERI is developing a PWR single assembly (PLUS7) test equipment to simulate the thermal flow in spent fuel assembly. In this study, the thermal conductivity of air at low pressure was derived to perform the thermal analysis of the canister in vacuum. In addition, thermal analyses were performed for the canister with backfill gases of helium, air, and a vacuum in the vertical orientation using the COBRA-SFS code. At low pressure, the thermal conductivity of air depends on pressure and temperature. The reduced thermal conductivity, kr (W/m-K) was calculated using the curve fit for air at reduced pressure in thin gaps presented in the General Electric Fluid Flow Handbook. 􀝇􀯥/􀝇􀬴 = 􀬵 􀬵􀬾 􀮼􀯍/􀯉􀰋 Where, k0 is the thermal conductivity at atmospheric pressure (W/m-K), P is the reduced (vacuum) pressure (Pa), δ is the gap size (m), T is the temperature (K), and C is the Lasance constant (7.657E-5 N/m-K). The thermal conductivity of air decreases as the pressure decreases. The reduced thermal conductivity of air at pressures of 400 Pa and 40 Pa was calculated to be 0.97 and 0.77, respectively. For the analysis in vacuum, no enhancement of the convective heat transfer was assumed (Nu=1.0). For the helium backfill, the peak cladding temperature was the lowest and the axial temperature profile was the flattest due to the higher thermal conductivity and lower density of the helium. For the vacuum backfill, the peak cladding temperature was the highest and temperature gradient was the sharpest due to the only radiative heat transfer effect in the fuel assembly.

본 연구는 1959년 일본의 재일조선인 북한송환(북송) 발표 직후인 2월 부터 6월까지 한일 양국의 국회에서는 재일조선인 북송에 대해 어떻게 논의를 전개하였는지 분석하였다. 즉, 본 연구의 질문은 ‘1959년 초반 한국 국회와 일본 국회는 재일조선인 북송 문제에 대해 어떠한 논의를 했는가?’이다. 이에 답하기 위해 본 연구는 한국 국회와 일본 국회의 1959년 회의록을 분석했고 그 결과는 다음과 같다. 우선 한국의 국회는 북한을 주권국가가 아니라고 보며 일본의 재일조선인 북송 계획에 반대 하는 논의를 하였다. 그러나 시간이 지나면서 국회 내의 의견 차이로 한 국 국회가 재일조선인 북송 문제 해결을 위한 구체적이고 본격적인 논의 를 진행하는 것은 어려웠다. 반면 일본의 국회는 한국 정부와의 관계 악 화를 우려해 재일조선인 북송 문제를 한일회담과 구분하여 처리하는 방 안을 논의했다. 또한, 일본 국회는 일본 정부가 북송 문제에 직접 관여하 지 않도록 국제적십자위원회가 재일조선인 북송 문제를 주도하여 해결해 야 한다는 방침을 세우며, 동시에 북송 실행을 위해 북한적십자사와의 회담에서 원만한 해결을 위해 논의를 확장하였다. 그러므로 재일조선인 북송 문제에 대한 1959년 2월부터 6월까지의 한국과 일본의 양국 국회 의 논의를 비교하면, 일본 국회의 논의가 한국의 국회 논의보다 구체적 이고 적극적이었다는 사실을 알 수 있다. 이후 1959년 12월 재일조선인 의 북송은 결국 실행되었다.

The intermediate shaft of sliding type is assembled with coated shaft joint and tube joint. Since the intermediate shaft plays a role of absorbing displacement change due to vibration, the intermediate shaft must have a sliding force value in an appropriate range. In this study, an intermediate shaft assembly system for post-processing of defective intermediate shafts was developed. The intermediate shaft assembly system consists of a wear count prediction model and an automatic wear system. A wear count prediction model was created with the initial assembly sliding force, quality, and set values. As a result of applying the intermediate shaft assembly device, the sliding force of the intermediate shaft was induced within the set value range. And it was prevented from the intermediate shaft defect and eliminated manual work.

Owing to their simplicity and ease of synthesis, carbon nanotubes (CNTs) have captivated attention of researchers. Many engineering applications have investigated the new features of nanostructured carbon nanotubes, such as large surface area, stiffness and durability. CNTs have opened up new opportunities for environmental improvement, pollution management and application in a variety of fields. Multiple types of pollution are produced as a result of population growth, urbanization and industrialization. CNTs are used to solve a variety of challenges, including environmental difficulties, water pollution, biomedical applications, and so on. It becomes an unavoidable present and future material. Different applications of CNTs have been presented in this review paper. CNTs are potential material having number of uses, including water purification, drug delivery, preservatives, catalysis, genetic engineering and artificial implants which are reviewed in this review article. This paper is presenting an explicit and systematic progress of CNTs for water treatment, medicinal uses drug delivery, artificial implants and so on, and a multitude of CNT applications in broad disciplines and their purification methods have been covered. The issues related to synthesis technologies, purification technology, bio-medicinal application and catalytic property of CNTs within the framework of different engineering applications and environmental impact are discussed in this study.

Gwaebultaeng is a cultural property of painting, a large Buddhist painting used for special ceremonies in Buddhism. It is stored in an indoor temple environment, and there is a greater risk of contamination and damage due to environmental factors compared to other cultural properties. In 2021, the treasure Hanging Painting of Anguksa Temple and storage chest stored in Geungnakjeon Hall of Anguksa Temple in Muju-gun, Jeollabuk-do were investigated. As a result, one genus and three species fungi, one species bacteria were found on the surface of the painting. In addition, five genera and 11 species fungi, eight genera and 12 species bacteria were confirmed on the surface of the storage chest. Among them, the same three species of Aspergillus genus were identified in both Gwaebultaeng and the storage chest. These results suggest the possibility of introduction and spread from airborne fungi in the indoor air outside the chest. Among the identified microorganisms, one genus and two species fungi in Gwaebultaeng and three genera and four species fungi, four genera and five species bacteria were identified as those that could cause damage to the storage chest. In addition, it was confirmed that one species fungus in Gwaebultaeng and one genus and two species fungi could cause harm to the human body. The results of this study will serve as a basis for careful discussion and management regarding the storage of cultural properties in the future.

본 연구는 2022년 2월 발발한 러시아-우크라이나 전쟁과 분쟁에 대응 하는 국제기구의 역할을 살펴보는 것을 목적으로 한다. 구체적으로 본 연구는 분쟁과 국제기구 간 관계에 대한 기존 논의를 확인하고, 우크라 이나 전쟁이 촉발한 국제기구의 최근 활동에 대해 살펴본다. 특히 UN 총회는 안전보장 이사회의 상임이사국 거부권 행사에 대해 유엔 총회의 견제 역할을 강조하는 4월 26일 결의안을 통과시켰고, 이는 제한적이지 만 기존의 유엔 개혁에 대한 진일보한 활동으로 평가된다. 우크라이나 전쟁 직후 안전보장이사회의 상임이사국 중 하나인 러시아의 지속적인 반대로 유엔 차원에서의 강력한 우크라이나 지원 및 러시아 규탄이 나타 나지 않았다. 이에 대한 대응으로 유엔 총회는 안전보장이사회의 상임이 사국 거부권 행사 행위를 총회에서 설명해야하는 결의안을 채택하였다. 이를 통해 본 연구는 국제기구가 분쟁발발을 억지하거나 분쟁을 종식시 키는 적극적 역할을 수행하기 어렵지만 국제분쟁이 국제기구의 기존 개 혁논의를 촉진시켜 분쟁에 대응하는 국제기구의 역할을 다각화하는 요인 이라는 점을 제시한다.

본 논문에서는 프리팹 구조물의 품질관리를 위한 딥러닝 및 비전센서 기반의 조립 성능 평가 모델을 개발하였다. 조립부 검출을 위 해 인코더-디코더 형식의 네트워크와 수용 영역 블록 합성곱 모듈을 적용한 딥러닝 모델을 사용하였다. 검출된 조립부 영역 내의 볼트 홀을 검출하고, 볼트홀의 위치 값을 산정하여 k-근접 이웃 기반 모델을 사용하여 조립 품질을 평가하였다. 제안된 기법의 성능을 검증 하기 위해 조립부 모형을 3D 프린팅을 이용하여 제작하여 조립부 검출 및 조립 성능 예측 모델의 성능을 검증하였다. 성능 검증 결과 높은 정밀도로 조립부를 검출하였으며, 검출된 조립부내의 볼트홀의 위치를 바탕으로 프리팹 구조물의 조립 성능을 5% 이하의 판별 오차로 평가할 수 있음을 확인하였다.

Dry head end process is developing for pyro-processing at KAERI (Korea Atomic Energy Research Institute). Dry processes, which include disassembling, mechanical decladding, vol-oxidation, blending, compaction, and sintering shall be performed in advance as the head-end process of pyro-processing. Also, for the operation of the head-end process, the design of the connecting systems between the down ender and the dismantling process is required. The disassembling process includes apparatus for down ender, dismantling of the SF (Spent Fuel) assembly (16×16 PWR), rod extraction, and cutting of extracted spent fuel rods. The disassembling process has four-unit apparatus, which comprises of a down ender that brings the assembly from a vertical position to a horizontal position, a dismantler to remove the upper and bottom nozzles of the spent fuel assembly, an extractor to extract the spent fuel rods from the assembly, and a cutter to cut the extracted spent fuel rods as a final step to transfer the rod-cuts to the mechanical decladding process. An important goal of dismantling process is the disassembling of a spent nuclear fuel assembly for the subsequent extraction process. In order to design the down ender and dismantler, these systems were analyzed and designed, also concept on the interference tools between down ender and dismantler were considered by using the solid works tool.

This study is to investigate fuel cladding temperature in a transport system for the purpose of developing a methodology for evaluating the thermal performance of spent fuel. Detailed temperature analysis in the transport system is important because the degradation mechanism of the fuel cladding is generally sensitive to temperature and temperature history. In such a system, the magnitude of the temperature change is determined by examining the temperature sensitivity of fuel assemblies and system components including fuel cladding temperature, considering the material properties, component specifications, component aging mechanism, and heat transfer mechanism. The sensitivity analysis is performed using heat transfer models by computational fluid dynamics for the horizontal transport system. The heat transfer within the system by convection, conduction and thermal radiation is calculated by thermal-hydraulic analysis code FLUENT. The calculation region is divided into a basket cell and a transport cask. The thermal analysis of the basket cell is for predicting the fuel cladding temperature. And the reason for analyzing the transport cask is to provide the boundary condition for the basket cell by reflecting the external environmental conditions. Here, the basket cell containing the spent fuel assembly is modeled on the homogeneous effective thermal conductivity. The purpose of this analysis is to evaluate fuel cladding temperatures for the following four main items. That is the effect of surface emissivity changes in basket due to the oxide layer of the fuel cladding, the effect of degradation of the canister backfill helium gas, the effect of fuel assembly position in basket cell on fuel cladding and basket temperatures in canister, and the effect of using the homogeneous effective thermal conductivity model instead of the fuel assembly in basket cell. As a result of the analysis, the maximum temperatures in basket cells are evaluated for the above four items. Thermal margins for each item are investigated for thermal performance requirements (e.g., peak clad temperature below 400oC).

In the design of a spent-fuel (SF) storage, the consideration of burnup credit brings the benefits in safety and economic views. According to it, various SF burnup measurement systems have been developed to estimate high fidelity burnup credit, such as FORK and SMOPY. Recently, there are a few attempts to localize the SF burnup measurement system in South Korea. For the localization of SF burnup measurement systems, it is very important to build the isotope inventory data base (DB) of various kinds of SFs. In this study, we performed DeCART2D/MASTER core follow calculations and McCARD single fuel assembly (FA) burnup analyses for Hanbit unit 3 and confirmed the characteristic of the isotope inventory over burnup. Firstly, the core follow calculations for Cycles 1~7 were performed using DeCART2D/MASTER code system. The core follow calculation is very realistic and practical because it considers the design conditions from its nuclear design report (NDR). Secondly, the Monte Carlo burnup analyses for single FAs were conducted by the McCARD Monte Carlo (MC) transport code. The McCARD code can utilize continuous energy cross section library and treat complex geometric information for particle transport simulation. Accordingly, the McCARD code can provide accurate solutions for burnup analyses without approximations, but it needs huge computing resources and time burden to perform whole-core follow calculations. Therefore, we will confirm the effectiveness of the single McCARD FA burnup analyses by comparing the DeCART2D/MASTER core follow results with the McCARD solution. From the results, the use of single FA burnup analyses for the establishment of the DBs will be justified. Various FAs, that have different 235U enrichments and loading pattern of fuel rods and burnable absorbers, were considered for the burnup analyses. In addition, the results of the sensitivity analyses for power density, initial enrichment, and cooling time will be presented.

The skeleton of fuel assembly is composed of top nozzle, bottom nozzle, grids, and guide tubes. In the reactor core, all the parts of the fuel assembly suffer degradations due to the condition of high temperature, pressure and water environment. Therefore, many material properties of high temperature mechanical strength, corrosion and irradiation resistance have been considered to choose the material for fuel assembly parts in the fuel development stage. The guide tubes have important roles to connect each parts and support the load of fuel assembly while the fuel is lifted. In Westinghouse 14×14 standard fuel assembly, Zircaloy-4 was used for the material of the guide tubes. Zircaloy-4 has a resistance to water corrosion and maintain good mechanical properties after the discharge from the core, so this alloy is also utilized for a fuel rod cladding material although the microstructure is slightly different due to the heat treatment difference. Thus, it is expected that there is no issue regarding the guide tube integrity after the discharge and during the storage in the pool, especially in case of low burn-up. However, the surface oxidation and resultant hydrogen pick-up can affect to the embrittlement to the Zr alloy. So, it is needed to know the actual status of spent fuel assembly by performing post-irradiation examination. In this study, the degradation level of the guide Tubes in low burn-up spent fuel assembly was investigated using the KAERI PIE facility in order to make some data which can be utilized to the baseline for evaluating the integrity of the spent fuel skeleton.

본 논문은 14~20대 국회 고용보험 관련 법률안 318건을 대상으로 의 원·정부의 입법관심 정책영역과 정책영역별 입법결과를 분석했다. 한 법 률 전체를 동일 정책영역으로 간주하는 기존 연구와는 달리 본 논문은 정책과정모형, 사회보험분석틀을 수정 및 보완하여 의안원문의 개별 개 정안을 정책영역별로 분류했다. 분석결과, <정책의제>에서 의원·정부의 입법관심이 가장 높은 정책영역은 실업급여사업이었고 정부의 이념적 성 향이 정책 입안에도 드러났다. 고용안정·직업능력개발사업은 경제상황에 따라 의원·정부의 입법관심이 증감했고, 모성보호사업은 정부보다 의원이 더 높은 입법관심을 보였다. 입법결과의 경우 정부는 고용안정·직업능력 개발사업의 정책 수에서 의원을 앞섰는데, 실업급여사업과 모성보호사업 은 정부안 가결률이 높고 입법성공 정책 수는 의원안에서 더 많았다. <행정체계>의 전체 정책영역에서 정부 정책안의 입법 성공률이 의원안보 다 더 높고 특히 재정정책은 정부가 주된 입법주체임을 확인했다. 결론 적으로 정책영역에 따라 법률적 변화를 견인하는 입법주체가 다르다는 점과 의원·정부의 입법관심 영역과 입법성공 가능성을 고려해 입법논의 가 이뤄진다면 효율적일 것이다.

본 논문은 민정 이양 후 1964년 3월부터 계엄령 직전인 5월까지 한국 국내의 한일회담 반대 운동과 관련하여 한국 국회에서 어떠한 논의가 진 행되었는지 고찰한다. 이를 위해 본 연구는 국회회의록, 신문기사 등의 1차 자료를 활용하여 분석한다. 본 논문은 핵심질문인 ‘1964년 한일회담 반대 운동과 관련하여 한국 국회 논의는 어떻게 진행되었는가?’에 대해 다음 두 가지의 특징으로 답한다. 첫째, 3-4월 국회에서는 여당과 야당 모두 한일회담 반대 운동을 우려하여 반대시위의 원인과 해결책을 찾으 며 한일회담과 관련된 논의를 하였다. 둘째, 5월 국회의 논의는 한일회 담 반대 운동에 대한 박정희 정권의 대처와 시위 주체의 위법성을 중심 으로 진행되었다. 특히 여당은 5월 20일의 한일회담 반대 운동을 공산주 의와 연결하여 보았고 일부 정치인들이 개입되었다고 판단하였다. 반면, 야당은 한일회담 반대시위를 여전히 평화적 시위라 여겨 박정희 정권의 대응이 과격하다고 주장하였다. 결국, 1964년 3월의 한일회담 반대 운동 확산 후 계엄령 전까지 한국 국회는 한국 국내의 불안정 상황을 해결하 기 위해 여당과 야당이 여러 논의를 시도하였지만 역부족이었다.

Detailed temperature distributions of the spent fuel are required to evaluate the long-term integrity of the dry storage system. In this study, a subchannel analysis method was established to obtain the detailed temperatures of a spent fuel using the COBRA-SFS code. The SAHTT (Single Assembly Heat Transfer Test) model was selected as the subchannel analysis. It was developed at the PNL to investigate heat transfer characteristics of spent PWR fuel under dry storage conditions. The SAHTT has a 15×15 rod array with simulated rods 0.42 in. (10.7 mm) in diameter. Control rod thimbles were modeled with unheated rods. The COBRA-SFS input consists a detailed subchannel model with 256 subchannels, 225 rods, and 8 slab nodes. The heat generation rate was axially uniform with total power of 1.0 kW. Subchannel analyses were performed for the vertical orientation under three different backfills of air, helium, and vacuum. For the vacuum backfill, the peak temperature was the highest and temperature gradients the sharpest only due to the radiation heat transfer effect. For the helium backfill, peak temperature was lowest and the axial profiles flattest due to the higher conductivity and lower density of helium. Subchannel analyses were also performed to evaluate the effect of thermal parameters such as surface emissivity, convective heat transfer coefficients, and flow resistance coefficients on the PCT (Peak Cladding Temperature). The PCT was affected by the emissivity of the fuel rod and the basket, and in particular, the basket emissivity had a greater effect. The PCT was affected by the Nusselt number, but the range of the Nusselt number is around 3.66. Therefore, the effect of the Nusselt number on the PCT will not be significant. As a result of the analysis according to the flow resistance coefficients, the PCT was affected by the wall friction factor, but the loss coefficients from the space grid had little effect. Subchannel technique obtained from this work can be used to predict the detailed temperature distributions of spent fuel assembly.

Dry storage is a predominantly used method as a spent nuclear fuel storage system after spent nuclear fuel is cooled in the spent fuel pool. Spent nuclear fuel is highly radioactive and it generates heat called decay heat originated by fission products and radiation. Therefore, temperature of spent nuclear fuel should be predicted whether its cladding temperature is maintained under 400°C, which is the allowable temperature limit of cladding in a dry storage. ANSYS Fluent and COBRA-SFS are predominantly used computational method to investigate the temperature of spent nuclear fuels in a dry storage. Herein, thermal analysis results with the methods were compared based on a Single Assembly Heat Transfer Test, which is a heat test with an electrically heated model of a single PWR fuel assembly in a dry cask performed at the Pacific Northwest Laboratory. Decay heat was 1kW and backfill gas was air. Fix temperature boundary condition is applied to inner shell according to measured temperature. In case of peak cladding temperature (PCT), Fluent predicted 240–284°C, while COBRA-SFS gave 243–292°C. The discrepancy between the codes is under 2.5%. The location where PCT took place was 3.65 m from the bottom of the assembly in both results. However, temperature difference between the upper and lower region of the assembly based on the Fluent was smaller than the temperature difference based on the COBRA-SFS. It means the heat was well transferred in an axial direction with Fluent compared to COBRA-SFS. In lower plenum region where air was naturally circulated, COBRASFS had disadvantages compared to Fluent because it modeled the lower plenum by single node, so it was hard to simulate convection heat transfer by natural circulation. natural circulation speed of air in a center region of the assembly was 0.07–0.1 m·s−1 in both cases.