In general, systems are developed by repeatedly performing the processes of design, analysis, manufacturing, and performance testing. In particular, systems with temperature, pressure, and flow rate often utilize computational fluid dynamics tools at the design stage. In this paper, we aim to verify the reliability of the analysis results of Solidworks Flow Simulation, which is widely used in heat flow analysis at the design stage. A tube furnace was manufactured, various experiments were performed, and a study was conducted to compare the analysis results. The details of the experiment are as follows. First, an experiment was conducted in which the heater was heated to 900°C without insulating the exposed part of the tube. The detailed contents of the experiment are as follows; - Heating heater and measuring temperature without supplying flow inside the tube, - Tube flow supply (25°C, 15 lpm air) and heater heating/temperature measurement. Second, an experiment was performed in which the exposed part of the tube was insulated (thickness 50 mm) and the heater was heated to 900°C. The detailed contents of the experiment are as follows; - Insulate the outside of the tube except for the flanges at both ends of the tube, and heat the heater and measure the temperature without supplying flow inside the tube. - Insulate the outside of the tube except for the flanges at both ends of the tube, supply flow rate inside the tube (25°C, 15 lpm air) and measure heater heating/temperature. - Insulate the flange of the flow supply section, heat the heater and measure temperature without supplying flow inside the tube. - Insulate the flange of the flow supply section, heat the supply air (277°C, 15 lpm) and measure the temperature using a heating gun without heating the heater. - Insulate the flange of the flow supply section, supply heated air (277°C, 15 lpm) and measure heater heating/temperature. - Insulate the flange of the flow supply section and measure temperature according to heater heating (900°C) and supply temperature (25°C, 277°C 15 lpm). The following results were derived from the experimental and analysis results. - When the exposed part of the tube is insulated, the temperature inside the tube increases and the steady-state power decreases compared to non-insulated. - In areas with insulation, the temperature error between experiment and analysis results is not large. - When flow rate is supplied, there is a large temperature error in experiment and analysis results. - The temperature change after the center of the heater is not large for a temperature change of 15 lpm flow rate. From these results, it can be seen that Solidworks Flow Simulation has a significant difference from the experimental results when there is a flow rate in the tube. This was thought to be because the flow rate acts as a disturbance, and this cannot be sufficiently accounted for in the analysis. In the future, we plan to check whether there is a way to solve this problem.

Pyroprocessing technology has emerged as a viable alternative for the treatment of metal/oxide used fuel within the nuclear fuel cycle. This innovative approach involves an oxide reduction process wherein spent fuel in oxide form is placed within a cathode basket immersed in a molten LiCl-Li2O salt operating at 923 K. The chemical reduction of these oxide materials into their metallic counterparts occurs through a reaction with Li metal, which is electrochemically deposited onto the cathode. However, during process, the generation of Li2O within the fuel basket is inevitable, and due to the limited reduction efficiency, a significant portion of rare earth oxides (REOx) remains in their oxide state. The presence of these impurities, specifically Li2O and REOx, necessitates their transfer into the electrorefining system, leading to several challenges. Both Li2O and REOx exhibit reactivity with UCl3, the primary electrolyte within the electrorefining system, causing a continuous reduction in UCl3 concentration throughout the process. Furthermore, the formation of fine UO2 powder within the salt system, resulting from chemical reactions, poses a potential long-term operational and safety concern within the electrorefining process.Various techniques have been developed to address the issue of UO2 fine particle removal from the salt, utilizing both chemical and mechanical methods. However, it is crucial that these methods do not interfere with the core pyroprocessing procedure. This study aims to investigate the impact of Li2O and REOx introduced from the electrolytic reduction process on the electrorefining system. Additionally, we propose a method to effectively eliminate the generated UO2 fine powder, thereby enhancing the long-term operational stability of the electrorefining process. The efficiency of this proposed solution in removing oxidized powder has been confirmed through laboratory-scale testing, and we will provide a comprehensive discussion of the detailed results.

In this paper, a basic study was conducted to observe the temperature inside the tube according to the heating temperature of the tube furnace. In a tube furnace, a tube is inserted, and the air space outside the tube is heated to increase the temperature of the gas inside the tube through conduction of the tube. Tube furnaces are widely used in research to capture volatile nuclides. In this case, a volatile nuclide capturing filter is inserted inside the tube, and an appropriate temperature is required to capture it. Since the tube furnace heats the air space outside the tube to the target temperature, a difference from the temperature inside the tube occurs. In particular, if a flow of gas occurs inside the tube, a larger temperature difference may occur. In order to confirm this temperature difference, an experimental device was constructed, and basic data was produced through several experiments. The following studies were conducted to produce data. First, the temperature of the air layer of the heating unit and the temperature inside the tube were measured in real time in the absence of gas flow inside the tube. Second, the temperature of the air layer of the heating unit and the temperature inside the tube were measured in real time while air having a certain temperature was flowing inside the tube. As a result of the experiment, when there is no flow inside the tube, when the heating target temperature is low, the temperature inside the tube is significantly lower than the target temperature, and when the target temperature is high, the temperature inside the tube approaches the target temperature. It was found that when there is about 20°C air flow inside the tube, the temperature inside the tube is significantly lowered even if the heating target temperature is high. In the future, additional research on changing the temperature of the gas flowing inside the tube will be conducted, and the results of this study are expected to greatly contribute to the design of a tube furnace that captures volatile nuclides.

The Korea Atomic Energy Research Institute is developing a nuclide management process that separates high heat, high mobility, and long half-life nuclides that burden the disposal of spent fuel, and disposes of spent fuel by nuclide according to the characteristics of each nuclide. Various offgases (volatile and semi-volatile nuclides) generated in this process must be discharged to the atmosphere below the emission standard, so an off-gas trapping system is required. In this study, we introduce the analysis results of the parameters that affect the design of the off-gas trapping system. The analyzed contents are as follows. The physical quantities of the Cs, Tc/se, and I trapping filters according to the amount of spent nuclear fuel, the maximum exothermic temperature of the Cs trapping filter and the absorbed dose by distance by Cs radioactivity were analyzed according to the amount of spent nuclear fuel. In addition, a three-dimensional CFD (Computational Fluid Dynamics) analysis was performed according to operating parameters by simply modeling the off-gas trapping system, which is easy to modify mechanical design parameters. It is considered that the analysis results will greatly contribute to the development of the off-gas trapping system design requirements.

Ti-Al-Si target and Cr-Si target are sputtered alternately to develop a multi-layered nitride coating on a steel mold to improve die-casting lifetime. Prior to the multi-layer deposition, a CrN layer is developed as a buffer layer on the mold to suppress the diffusion of reactive elements and enhance the cohesive strength of the multi-layer deposition. Approximately 50 nm CrSiN and TiAlSiN layers are deposited layer by layer, and form about three μm-thickness of multi-layered coating. From the observation of the uncoated and coated steel molds after the acceleration experiment of liquid metal injection casting, the uncoated mold is severely eroded by the adhesion of molten metallic glass. On the other hand, the multi-layer coating on the mold prevents element diffusion from the metallic glass and mold erosion during the experiment. The multi-layer structure of the coating transforms the nano-composite structured coating during the acceleration test. Since the nano-composite structure disrupts element diffusion to molten metallic glass, despite microstructure changes, the coating is not eroded by the 1,050 oC molten metallic glass.

피암터널은 낙석방지시설 중 하나로 비교적 큰 낙석이 발생할 수 있는 급경사지 도로위에 건설된다. 일반적으로 피암터널은 약 200kJ에서 3,000kJ 까지의 낙석에너지에 저항할 수 있도록 설계된다. 기존 연구에서 이러한 피암터널의 효율성을 증대하기 위하여 콘크리트 충전강관(CFT, Concrete-Filled Tube)를 주구조체로 사용하는 신형식 피암터널을 제시하였다. CFT를 주구조체로 활용함으로서 급속시공이 가능하며 높은 하중저항 능력과 연성 또한 확보할 수 있는 장점이 있다. 하지만, 기존 연구에서는 선현 탄성 해석을 통하여 거동을 분석하여 한계를 가지고 있어 보다 실제적인 낙성하중을 고려한 3차원 유한요소해석을 통하여 제안된 피암터널의 거동을 분석할 필요가 있다. 본 연구에서는 먼저 제안된 피암터널 주구조체에 대한 실제 낙석하중을 포함한 3차원 유한요소해석을 개발하였다. 이후 최대 낙석에너지에 대한 제안된 피암터널 주구조체의 낙석 저항능력에 대하여 연구를 수행하였다.