Ag-containing aluminosilicate sorbents capable of capturing iodine were prepared by sol-gelation from Na, Al, and Si alkoxides using co-solvent exchange, Ag/Na ion exchange, solvent exchange, and ambient-pressure drying. The Na+AlSi-OH gel was prepared using sodium methoxide (NaOMe): aluminum tri-sec-butoxide (Al(OsBu)3): tetraethyl orthosilicate (TEOS) molar ratios of 1.05:1:1, 1.3:1.1:1, 1.5:1.3:1. The solvent effect on textural properties such as Brunauer-Emmett-Teller (BET) surface areas and pore size distributions and Ag0 particle sizes was investigated using water with high surface tension, isopropanol and n-heptane with low surface tension. The BET surface area, average pore size, and cumulative pore volume for sorbents strongly increased with decreasing surface tension of solvents and increasing Al/Si atomic ratios. In addition, Ag0 particle sizes increased with decreasing surface tension of solvents.

The damaged spent fuel rods must be stabilized by encapsulation or dry re-fabrication technologies before geological disposal. For applying the dry re-fabrication technology, we manufactured a vertical type furnace to perform both fuel material recovery from damaged fuel rods by oxidative decladding and sinterability improvement of fuel powder by repetition of oxidative and reaction treatment. A horizontal type furnace provides only a diffusion-controlled reaction resulting in longer reaction time and decreasing amount of powder for oxidation and reduction, whereas a vertical type furnace with a submerged gas distributor gives rapid reaction due to flowing gas-solid contact by fluidization. For observation of fluidization behaviors of uranium oxides at room temperature, fluidized column was prepared with transparent cylindrical tube, pressure transmitter and gas flow meter. Number of size of orifice holes was determined by equations in Fluidization Engineering [D.Kunii, O. Levenspiel]. Before uranium oxide test, as surrogates, WO2 (10.8 g/cm3) and Ta2O5 (8.2 g/cm3) powder similar to density of UO2 (10.96 g/cm3) and U3O8 (8.3 g/cm3), respectively were used to achieve fluidization operation conditions in the region from minimum to expanded fluidization. Fluidization behaviors and pressure drop of powder bed was observed according to operation parameters such as gas velocity, number and size of orifice holes, and powder amount.

Interests in molten salt reactor (MSR) using a fast spectrum (FS) have been increased not only for having a high power density but for burning the high-level waste generated from nuclear power plants. For developing the FS-MSR technologies, chloride-based fuels are considered due to the advantage of higher solubility of actinides and lanthanides over fluoride-based salts. Despite significant progress in development of MSR technology, the manufacturing technology for production of the fuel is still insufficiently understood. One of the option to prepare the MSR fuel is to use products from pyroprocessing where oxide form of spent nuclear fuel is reduced into metal form and useful elements can be collected via electrochemical methods in molten salt system at high temperature. In order to chlorinate the products into chloride form, previous study used NH4Cl to chlorinate U metal into UCl3 in an airtight reactor. It was found that the U metal was completely chlorinated into chloride forms; however, impurities generated by the reaction of NH4Cl and reactor wall were found in the product. Therefore, in this work, the air tight reactor was re-deigned to avoid the reaction of reactor wall by insertion of Al2O3 crucible inside of the reactor. In addition, the reactor size was increased to produce UCl3 over 100 g. Using the newly designed reactor, U metal chlorination experiments using NH4Cl chlorinating agent were performed to confirm the optimal experimental conditions. The detailed results will be further discussed.

Irradiated uranium dioxide in damaged used fuel could oxidize during transportation, interim storage or disposal, resulting that the fuel pellet fragments are reduced to a grain-sized powder that can easily escaped from the damaged rod. It has been reported that oxidized spent fuel (i.e. U4O9+x) that was in contact with water could increase the dissolution rate by making the grain boundaries more accessible to the water. Therefore, the damaged used fuel requires stabilization technology including nuclear material recovery, pellet manufacturing process, and stabilization fuel rod manufacturing that can secure safety in terms of permanent disposal. In this study, we prepared pure UO2 and SIMFUEL pellets that are a mixture of UO2 and surrogated metallic oxides for fission products equivalent to a burn-up of 35 GWd/tU and 55 GWd/tU as the stabilized spent fuel. The UO2 and fission products powders were milled and pressed into pellets at 250 MPa and sintered at 1,550°C and 1,700°C for 6 hours in an atmosphere of 4%H2-Ar. The prepared UO2 and SIMFUEL pellets were placed in PTFE Teflon vessels and filled with deionized water to identify the leaching behavior by a long-term leaching experiment under the similar condition to a repository for the safe disposal.

B4C/Al composite is mainly used for neutron absorbing materials, which is one of the components of equipment that manages spent nuclear fuel. There are various processes for manufacturing neutron absorbing materials, but most of them are based on the powder metallurgy. In this study, B4C/Al composite in which the reinforcement was uniformly dispersed was manufactured by using the stir casting process. The microstructure, thermal neutron absorption rate, mechanical properties and dispersibility of the reinforcement of the prepared B4C/Al composite were analyzed.

The crisis of climate change aroused international needs to reduce the greenhouse gas emission in energy sector. Government of South Korea formulated an agenda of carbon neutrality through announcing 2050 Net-Zero Carbon Scenario A and B in October 2021. As the power supply from renewable energy increases, it becomes a core element to take into account the daily intermittency of renewable energy in analyzing the upcoming energy plans. However, the existing yearly Load Duration Curve is insufficient for applying day and night power change in daily scale into energy mix analysis, since it derives the energy mix for whole year on the basis of classifying annual base load and peak load. Therefore, a new energy mix simulation model based on the daily power load and supply simulation is needed for the future energy analysis. In this study we developed a new model which simulates the average power supply and demand daily (over a 24 hour period) for each season. The model calculates the excess and shortage power during day and night by integrating each energy’s daily power pattern. The 2050 Net-Zero Carbon Scenario A was used for the model verification, during which the same amounts of power production from each energy source were applied: nuclear, renewable, carbon-free gas turbine, fuel cell and byproduct gas. Total power demand pattern and renewable energy production pattern were drawn from the data of 2017 power production, and Pumped-storage Hydroelectricity and Energy Storage System were used as day-to-night conversion. Detailed assumptions for each energy were based on the Basis of Calculation for Net-Zero Carbon Scenario from Government. The model was verified with three cases which were divided depending on the method of hydrogen production and whether the Curtailment and Conversion Loss (CCL) of renewable energy were considered or not. Case 1 assumed production of hydrogen occurred for 24 hours while not considering CCL, had 0% relative error in comparison of total annual power production, and case 2, considering CCL, had a 1.741% relative error. Case 3 assumed production of hydrogen occurred only during daytime with excess power and CCL consideration, yielded 0.493% relative error in total amount of hydrogen production, confirming that the model sufficiently describes the Government’s Scenario A with the input of total power production. This model is expected to be used for analyzing further energy mix with different ratios of each energy source, with special focus on nuclear and renewable energy sources.