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.

As part of strengthening pyro safety measures, the Korea Atomic Energy Research Institute is developing LIBS (Laser-Induced Breakdown Spectroscopy) application technology to analyze molten salt components in electrolytic recovery device in real time. LIBS performs qualitative and quantitative analysis by analyzing the spectrum of energy emitted by atomizing and ionizing elements on the surface of a salt sample with a high-focused laser. Since salt easily corrodes metal, it must be managed in an environment with a dew point of -40°C or lower. In this study, we designed and manufactured a device that places a rod-type sampling stick on a mounting base, automatically moves it to the optimal measurement position for LIBS, and retrieves the sample. Its characteristics are as follows. First, LIBS is stationary and does not move. Second, the sample stick is placed on a mounting base and can rotate 360 degrees. Third, according to the command, the sample stick automatically moves to the optimal measurement position of LIBS with three degrees of freedom (X, Y, Z). Fourth, the salt attached to the sampling stick is recovered for chemical analysis by driving the gripper mounted at the bottom of the Z axis, Z axis, and rotation axis (R). The X, Y, and Z movement distances of this device are each 100 mm, rotation is 360 degrees, grip stroke is 50 mm, and position accuracy is ±20 m. Once the performance test of the automated salt sample analysis device is completed, it will be installed in a dry room with a dew point of - 40°C or lower. Samples will be collected remotely in connection with the electrolytic recovery device and gantry robot built in the dry room. We plan to conduct experiments to seat the sample stick. Ultimately, we plan to conduct comprehensive experiments in conjunction with LIBS.

It has been investigated on the management of Strontium-90 in KAERI. It is needed to separate the solute from the salt solution for the recovery of strontium after the chlorination of the strontium oxide in molten salt. A vacuum distillation technology was used for the separation of strontium from the molten salt in our previous study. Strontium chloride was successfully carbonated by reactive distillation of SrCl2 – K2CO3 – LiCl – KCl system. In this study, it was tried to develop another route to recover strontium from the salt solution by a solid-solid reaction for avoiding the entrainment of product and the salt-K2CO3 reaction. Reactive distillation experiments were carried out for SrCl2 - K2CO3 – LiCl – KCl system. The carbonation temperature and pressure were 520°C and 0.8 bar. After the carbonation reaction, the temperature was elevated to 820°C to remove KCl from the reaction product. SrCO3 and KCl peaks were found in the XRD analysis of the residual product. It could be concluded that SrCl2 can be successfully carbonated after salt removal by the solid-solid reaction.

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.

It has been investigated on the management of the nuclides in KAERI. Strontium-90 is a high heatgenerating nuclide in spent nuclear fuel. It is needed to separate the salt from the salt solution for the recovery of strontium after the chlorination of the strontium oxide in molten salt. A vacuum distillation technology was used for the separation of strontium from the molten salt. It was investigated on operating conditions of reactive distillation process for the recovery of the strontium from the salt solution. At a reduced pressure, considerable amount of the carbonation agents such as K2CO3 and Li2CO3 were reduced during heating in the distiller due to the thermal decomposition. Therefore, the two step process was proposed, which is composed of a reaction step at an atmospheric pressure and a salt distillation step at a reduced pressure. In the reaction step, the condition of low temperature and high pressure is suitable to suppress the decomposition of the carbonation agent. In the salt distillation step, reduced pressure is preferable at a suitable temperature depending on the evaporation rate of the salt.

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.