Decontamination of spent nuclear fuel from decommissioned nuclear reactors is crucial to reduce the volume of intermediate-level waste. Fuel cladding hulls are one of the important parts due to high radioactivity. Their decontamination could possibly enable reclassification as low-level waste. Fuel cladding hulls used in research reactors and being developed for conventional light water reactors are Al-Mg and Fe-Cr-Al alloys, respectively. Therefore, the recovery of these component metals after decontamination is necessary to reduce the volume of highly radioactive waste. Electrochemical approach is often chosen due to its simplicity and effectiveness. Non-aqueous solvents, such as molten salts (MSs) and ionic liquids (ILs), are preferred to aqueous solvents due to the absence of hydrogen evolution. However, MSs and ILs are limited by high temperature and high synthesis cost, along with toxicity issues. Deep eutectic solvents (DESs) are synthesized from a hydrogen bond acceptor (HBA) and donor (HBD) and exhibit outstanding metal salt solubility, wide electrochemical window, good biocompatibility, and economic production process. These characteristics make DES an attractive candidate solvent for economic, green, and efficient electrodeposition compared with aqueous solvents such acids or nonaqueous solvents such as MSs or ILs. In this research, the feasibility of electrodeposition of Al-Mg and Fe-Cr-Al alloys in ChCl:EG, the most common DES synthesized from choline chloride (ChCl) and ethylene glycol (EG), will be tested. A standard three-electrode electrochemical cell with an Au plated working electrode and Al wires for counter and reference electrodes is utilized. Two electrolyte solutions (Al-Mg and Fe-Cr-Al) are prepared by dissolving 100 mM of each anhydrous metal chloride salts (AlCl3, MgCl2, CrCl3, and FeCl2) in ChCl:EG. Cyclic voltammogram (CV) is measured at 5, 10, 15, and 20 mV·s−1 to observe the redox reactions occurring in the solutions. Electrodeposition of each alloy is performed via chronoamperometry at observed reduction potentials from CV measurements. The deposited surfaces and cross-sections are examined by scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) to analyze the surface morphology, cross-section composition, and thickness. Authors anticipate that the presence of different metals will greatly affect the possibility of electrodeposition. It is expected that although all metals are distributed throughout the surface, the morphology, in terms of particle size and shape, would differ depending on metals. Different metals will be deposited by layers of an approximate thickness of a few μm each. This research will illustrate a potential for recovery and electrodeposition of other precious radioactive metals from DES.

Cutting reactor pressure vessels (RPV) into acceptable sizes for waste disposal is a key process in dismantling nuclear power plants. In the case of Kori-1, a remote oxyfuel cutting method has been developed by Doosan Heavy Industry & Construction to dismantle RPVs. Cutting radioactive material, such as RPV, generates a large number of fine and ultrafine particles incorporating radioactive isotopes. To minimize radiological exposure of dismantling workers and workplace surface contamination, understanding the characteristics of radioactive aerosols from the cutting process is crucial. However, there is a paucity of knowledge of the by-products of the cutting process. To overcome the limitations, a mock-up RPV cutting experiment was designed and established to investigate the characteristics of fine and ultrafine particles from the remote cutting process of the RPV at the Nuclear Decommissioning Center of Doosan Heavy Industry & Construction. The aerosol measurement system was composed of a cutting system, purification system, sampling system, and measurement device. The cutting system has a shielding tent and oxyfuel cutting torch and remote cutting robot arm. It was designed to prevent fine particle leakage. The shielding tent acts as a cutting chamber and is connected to the purification system. The purification system operates a pressure difference by generating an airflow which delivers aerosols from the cutting system to the purification system. The sampling system was installed at the center of the pipe which connects the shielding tent and purification system and was carefully designed to achieve isokinetic sampling for unbiased sampling. Sampled aerosols were delivered to the measurement device. A high-resolution electrical low-pressure impactor (HR-ELPI+, Dekati) is used to measure the size distribution of inhalable aerosols (Aerodynamic diameter: 6 nm to 10 μm) and to collect size classified aerosols. In this work, the mock-up reactor vessel was cut 3 times to measure the number distribution of fine and ultrafine particles and mass distribution of iron, chromium, nickel, and manganese. The number distribution of aerosols showed the bi-modal distribution; two peaks were positioned at 0.01−0.02 μm and 0.04–0.07 μm respectively. The mass distribution of metal elements showed bi-modal and trimodal distribution. Such results could be criteria for filter selection to be used in the filtration system for the cutting process and fundamental data for internal dose assessment for accidents. Future work includes the investigations relationships between the characteristics of the generated aerosols and physicochemical properties of metal elements.

To dispose of spent nuclear fuel, the most promising method is disposal in a deep geological repository with a multi-barrier system. Among the multi-barrier system, canisters are used to contain the spent nuclear fuel. A role of the canister is to withstand corrosion load from the deep geological environment as possible as long. Corrosion processes consist of corroding agents transport to the canister surface and electrochemical reactions between the corroding agents and the canister surface. According to previous King’s electrochemical experiments, the mass-transport rate of corroding agents is slower than the electrochemical reaction rate with copper when the canister is surrounded by dense bentonite blocks. Therefore, the mass-transport rate is a rate-determining step for the whole corrosion process. Despite of the importance of transportation of oxidizing agents in bentonite, the transportation process was not paid attention. For example, existing models which are called continuum models assumed that the corroding agents pass through the pore in the porous medium because the continuum model does not consider the fracture networks in the bentonite. Here we develop a dualpermeability and dual-porosity model. In this model, the transport of corroding agents is considered that they pass through fracture within the porous medium. The difference between the dual-permeability and dual-porosity model is whether the corroding agents can pass through the pore. The dual-permeability model assumed that the mass-transport occurs within both fracture and porous medium. On the other hand, the dual-porosity model assumed that the mass-transport occurs only within fractures. Through both models, we found that the transport rate in the fractures is much higher than through the pores, and the canister lifetime at a point where contacting the fracture tip is much shorter than other parts when the canister lifetime is calculated by the transport-governed condition. In addition, the temperature distributions in the fracture are different compared to the existing continuum model. Our results show the effect of fractures in terms of not only corroding agents transport but also the canister lifetime. We anticipate our model to be a first step for the corrosion estimation model coupled with fracture networks.

Corrosion of copper (Cu) canisters is one of the important factors to ensure the safety of a deep geological repository site. This is because the corrosion of a canister may induce failure of the canister which can lead to a release of radionuclides into the environment. Corrosion of canisters for highlevel wastes is affected by the following multiphysics: thermal-hydraulics, transportation of chemical species, chemical reactions, and interface reactions. This research aimed to develop a multiphysics numerical model for the corrosion of spent nuclear fuel canisters for a deep geological repository in South Korea. The multiphysics model is based on MOOSE (Multiphysics Object-Oriented Simulation Environment) which uses a finite element method. In the multiphysics model, the following multiphysics are coupled and solved together for a deep geological repository design of South Korea: interface redox reactions, porous flow, and heat transport in porous flow. The proposed model was validated with experimental data before being applied to a KAERI reference disposal unit. It was found that the corrosion potential of a Cu canister shows an uneven distribution of corrosion potential along with the surface. In addition, top, bottom, and side surfaces of the canisters show a different lifetime and corrosion potential. Important redox reactions for corrosion are changed along with time from a reduction of O2 and anodic dissolution of Cu by Cl− to sulfidation of Cu and reduction of water. The proposed model will be coupled with some important chemical reactions in engineering buffers and will be the base for the understanding of the behavior of Cu canisters in the KAERI reference disposal unit.

The denuclearization of North Korea was unpredictable and resulted in radical changes. Despite the skepticism and disappointment surrounding denuclearization, it is important for certain verification technologies to establish what is technically possible or practically impossible, and how reliable these technical means are. This article presents the technical hurdles in nuclear verification by systematically categorizing them into issues of correctness and completeness. Moreover, it addresses the safety and security risks during the denuclearization process, including the radiological impact on humans, environmental effects, and the illegal transfer of material, information, and technologies.

The objective of this study was to evaluate the quality characteristics of mozzarella cheese added wine concentrate. Mozzarella cheese was produced with different additives of wine concentrate which were 0~5%. The pH and the total acidity of the Cheese were analyzed. We also examined the radical scavenging activities for the antioxidant effect of samples and evaluated for their total polyphenol, and total flavonoid contents. The pH of Meoru wine cheese (6.28~6.37) was significantly higher and total acidity tended to decrease compared to that of the control. L* (lightness) of the wine cheese decreased with increasing amounts of wine concentrates whereas a* (redness) tended to increase. In the texture profile analysis, Meoru wine cheese showed higher values of hardness, gumminess, and chewiness. The ABTS radical scavenging activity of Meoru wine cheese showed the highest value when wine concentrate amounts were 2%. The DPPH radical scavenging activity was significantly increased in cheese added with wine concentrate. Total polyphenol contents and total flavonoid contents of Meoru wine cheese tended to increase with increasing amounts of wine concentrate. This research result highlights the positive influence of wine concentrate addition in cheese. Also, these results are expected to impact the experience programs in farm wineries.

In this study, we attempted to compare the maceration processes in the white wine made of Muscat of Alexandria grape having different the fermentation· maceration periods. These wine were sampled and analyzed by fermentation periods. The pH of wines ranged from 3.25 to 3.27 and the total acidity of wines ranged from 0.85~0.91% (w/v) on the 12th day of fermentation period. The ethanol concentration in these wines increased during the alcoholic fermentation period, on the other hand, the soluble solid concentrations (°Brix) decreased. The b value (yellowness) of Muscat of Alexandria wine was the highest at 8.31 in C treatment, which is a wine with a long maceration period, and B (7.19) and A (5.27) were significantly decreased as the maceration period was shorter. The total polyphenol and tannin content of wine increased with the period of maceration. Total polyphenol and tannin contents had the highest values (64.20 and 67.11 mg%, respectively) in the C treatment, which is a wine with a long maceration period on the 12th day of fermentation period. The physiological activities of Alexandria wine were highest level in the treatment with a long maceration period. As a result, this study provides useful scientific information that quality characteristics and physiological activities in white wine.

In this study, vin chaud were manufactured with eight types of vin chaud-bomb containing different amounts of ingredients, and Campbell Early wine. Samples were analyzed for pH, total acidity, volatile acidity, ethanol content, total polyphenol, and anthocyanins, and radical scavenging activities for antioxidant effect. Based on the results of this study the pH of the samples ranged from 3.34 to 3.41 and the total acidity of wines ranged from 0.55 to 1.00%. The alcohol contents of the vin chaud samples ranged from 3.8~5.8% to and the color intensity of the vin chaud samples was higher than that of the wine. Total polyphenol content was 145.90~262.98 mg% and the tannin content of the C-1 (236.90 mg%) was the highest among the samples. The ABTS and DPPH radical scavenging activity of the samples were 57.39~75.10% and 63.71~80.00% respectively. α-Glucosidase inhibitory activity ranged from 21.54 to 33.49%, on the other hand, wine was not detected and tyrosinase inhibitory activity had the highest values (39.26%) in the C-1 sample. The findings of the present study provide insightful scientific information on vin chaud, and forms a basis for further innovations in the food and wine industry.

The objective of this study was to investigate the quality characteristics of Cheongsoo wine using freeze concentration fermented with 5 kinds of yeast strains (Saccharomyces cerevisiae EJ18, EJ30, HK22, HK32 and Fermivin). We compared the characteristics, volatile flavor component and physiological activity of 5 wines. The freeze concentration can increase the sugar concentration in grape juice by reducing its water content and the alcohol content of freeze-cententrated Cheongsoo wines ranged between 15.0~15.8%. The pH of wines ranged from 2.92 to 2.94 and the total acidity and soluble solid of wines ranged from 12.40~13.27. °Brix. The major organic acid in the wines was tartaric acid (4.49~5.11 mg/mL) and malic acid (7.00~7.97 mg/mL). It contains higher functional compounds in wine fermented with yeast (EJ18, EJ30, HK22, HK32) than wine fermented with fermivin. α-glucosidase and tyrosinase inhibitory activity had the highest values (78.87% and 62.25%) in wine fermented with HK22 and EJ18 yeast, respectively. 16 volatile flavor compounds (alcohols, esters, ketones, acids, and others) were detected in the Cheongsoo wines by freeze concentration. These results provide useful information that the quality characteristics of wine developed by the freeze-concentration method using grapes cultivated in Korea.