Molten Salt Reactor (MSR) is one of the 4th generation nuclear power systems which is its verified technology in physically and chemically. Among the various salts used for MSR system, the eutectic composition of NaCl-MgCl2 system maintains the liquid state at around 450°C, in the same time, it has high solubility for nuclear fuel chlorides. This characteristic has high advantage for lowering the operating temperature for the MSR, which could reduce the problem of hightemperature corrosion by salt for structural materials significantly. In particular, since MgCl2 has the similar standard reduction potential with nuclear fuel, is used as a surrogate for, many basic researches have been conducted for verifying characteristic of MgCl2. It is well-known that main short-advantage of MgCl2 is hygroscopic properties. MgCl2 changes to MgCl2-xH2O state easily by absorbing moisture in air condition. The hydrated MgCl2 is producing MgOHCl by thermally decomposing at high temperature, the formed MgOHCl corrodes structural materials, even small amount of MgOHCl gives significant damage. Therefore, the purification of MgCl2 has been required for long-term operation of MSR using MgCl2 as a base salt. In this study, the purification of eutectic composition salt for NaCl-MgCl2 has been mainly performed by considering its thermodynamic properties and electrochemical characteristic, and the experimental results have been discussed.

Radioactive iodine released from nuclear power plants has been recognized to pose significant risks and environmental hazards. In response to these challenges, extensive investigations into iodine sorbents have been conducted with a particular focus on the utilization of layered double hydroxides (LDH) as a promising candidate. Herein, we have focused on the investigation of LDH materials featuring diverse transition metals for their synthesis, with specific emphasis on CoAl LDH for its proficiency in removing iodine species, particularly IO3 –. Nevertheless, a comprehensive understanding of the removal mechanisms employed by these LDH materials remained elusive. Hence, the primary aim of this study is to elucidate the intricacies of the removal mechanisms through sorption tests, spectroscopic techniques, and theoretical chemistry analyses, subsequently contrasting the experimental outcomes with computational results. For the experimental facet, the synthesis of CoAl LDH was conducted utilizing 0.15 mol L−1 of Co(NO3)2⋅6H2O and 0.06 mol L−1 of Al(NO3)3⋅9H2O to attain a molar ratio (M2+:M3+) of 2.5:1. Subsequently, pH-dependent IO3 – sorption tests were carried out, coupled with X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy, facilitating the elucidation and discourse of the removal mechanism. The theoretical chemistry in this research harnessed ab initio molecular dynamics (AIMD) simulations for structural modeling, atomic density profiles, radial distribution function, analysis of oxide species, and MD-EXAFS spectrum analysis. In summary, this study aims to elucidate iodine removal mechanisms using diverse experimental results, culminating in the revelation that ion-exchange with NO3 – present in the interlayer predominates as the principal mechanism for IO3 – removal. Notably, a distinct spectral feature at approximately 33,190 eV emerged, defying identification through XANES and EXAFS analyses conducted under experimental conditions. In the AIMD simulations, meticulous scrutiny of individual iodine atoms uncovered the prevalence of I−O and I−O−H molecular species, marked by interactions between O and H atoms, with a coordination number of I−O = ~3. This transformation was primarily instigated by proton hopping. As a result, the comparative investigation reveals the dominance of IO3 – intercalation in the CoAl LDH material with the potential to undergo a transformation to the I−O−H molecule upon interaction with protons.

The nuclear fuel that melted during the Fukushima nuclear accident in 2011 is still being cooled by water. In this process, contaminated water containing radioactive substances such as cesium and strontium is generated. The total amount of radioactive pollutants released by the natural environment due to the nuclear accident in Fukushima in 2011 is estimated to be 900 PBq, of which 10 to 37 PBq for cesium. Radioactive cesium (137Cs) is a potassium analog that exists in the water in the form of cations with similar daytime behavior and a small hydration radius and is recognized as a radioactive nuclide that has the greatest impact on the environment due to its long half-life (about 30 years), high solubility and diffusion coefficient, and gamma-ray emission. In this study, alginate beads were designed using Prussian blue, known as a material that selectively adsorbs cesium for removal and detection of cesium. To confirm the adsorption performance of the produced Prussian blue, immersion experiments were conducted using Cs standard solution, and MCNP simulations were performed by modeling 1L reservoir to conduct experiments using radioactive Cs in the future. An adsorption experiment was conducted with water containing standard cesium solution using alginate beads impregnated with Prussian blue. The adsorption experiment tested how much cesium of the same concentration was adsorbed over time. As a result, it was found that Prussian blue beads removed about 80% of cesium within 10-15 minutes. In addition, MCNP simulation was performed using a 1 L reservoir and a 3inch NaI detector to optimize the amount of Prussian blue. The results of comparing the efficiency according to the Prussian volume was shown. It showed that our designed system holds great promise for the cleanup and detection of radioactive cesium contaminated seawater around nuclear plants and/or after nuclear accidents. Thus, this work is expected to provide insights into the fundamental MCNP simulation based optimization of Prussian blue for cesium removal and this work based MCNP simulation will pave the way for various practical applications.

When decommissioning of nuclear facilities happens, large amounts of radioactive wastes are released. Because costs of nuclear decommissioning are enormous, effective and economical decontamination technologies are needed to remove radioactive wastes. During NPP operation, corrosion product called Chalk River Unidentified Deposits (CRUD) is generated. CRUD is an accumulation of substances and corrosion products consisting of dissolved ions or solid particles such as Ni, Fe, and Co on the surface of the NPP fuel rod coating. CRUD is slowly eroded by the circulation of hot pressurized water and later deposits on the fuel rod cladding or external housing, thereby reducing heat production by the nuclear fuel. Decontamination of radiologically contaminated metals must be performed before disposal, and several methods for decontaminating CRUD are being studied in many countries. Decontamination technology is an alternative to reducing human body covering and reducing radioactive waste disposal costs, and much research and development has been conducted to date. Currently, the importance of decontamination is emerging as the amount of waste stored in radioactive waste storage is close to saturation, and the amount of radioactive waste generated must be minimized through active decontamination. In this study, a preliminary study was conducted on the removal of CRUD by multiple membrane in an electro-kinetic process using an electrochemicalbased decontamination method. Preliminary research to develop a technology to electrochemically remove CRUD by using a self-produced electrochemical cell to check the pH change over time of the CRUD cell according to voltage, electrolyte, membrane and pH change.

Wide-area surface decontamination is essential during the sudden release of radioisotopes to the public, such as nuclear accidents or terrorist attacks. A spray coating composed of a reversible complex between poly (vinyl alcohol) (PVA) and phenylboronic acid-grafted poly (methyl vinyl ether-alt-mono-sodium maleate) (PBA–g–PMVE–SM) was developed to remove radioactive cesium from surfaces. The simultaneous spay of PVA and PBA–g–PMVE–SM aqueous polymer solutions containing Cs adsorbent to contaminated surfaces resulted in the spontaneous formation of a PBA–diol ester bond-based gel-like coating. The Cs adsorbent suspended in the gel-like coating selectively removed Cs-137 from the Cs-contaminated surface. The used gel-like coating were removed from surfaces by simple water rinsing. This recovery way has advantages compared with costly incineration to remove the organic materials for final disposal/storage of the radioactive waste. Thus, our spray coating is suitable for practical wide-area surface decontamination. In radioactive tests, the hydrogel containing Cs-adsorbent showed substantial Cs-137 removal efficiencies of 96.996% for painted cement and 63.404% for cement, which are 2.33 times better than the values for the commercial surface decontamination coating agent DeconGel.

A Partially hydrolyzed poly (vinyl acetate) (PHPVA)-borax complex-based gel-like coating was successfully developed for the decontamination of Simulated nuclear fallout (SFO) from surfaces. The sprayable coating was self-generated on the surface by borate-diol ester bonds after simultaneously mixing two solutions of borax and PHPVA. The SFO particles, synthesized at 1,200°C for melting, were glassy while some crystalline phases (e.g., SiO2 and Fe2O3) existed together. The SFO particles were fixed onto the Stainless steel (SS) substrate by dropping and evaporating water. for examination of the dust-removal performance of PHPVA-borax based coating. The dusts on the SS surface was successfully removed by casting the PHPVA-borax based coating within 1 minute, demonstrating the excellent dust-removal property of the PHPVA-borax based coating. The used PAB complex in wet state was recovered by using vacuum suction machine in short time. The solid-state PHPVA-borax based film was self-delaminated from the SS substrate after fully drying the used PHPVA-borax coating but this requires long period of time.

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.

This paper evaluates the adsorptive removal of sunset yellow (SY) from aqueous solutions using a new magnetic glycodendrimer (MGD). To synthesize the MGD, chitosan dendrons were cultivated on amine-functionalized magnetic graphene oxide. A number of analytical methods were employed to physicochemically characterize the synthesized MGD. Batch adsorption conditions were optimized using the Box–Behnken design. An optimized initial SY content of 633 mg/L, an optimized contact time of 33.37 min, and an optimized pH of 3.72 maximized the MGD adsorption capacity to 485 mg/g. The Langmuir isotherm was employed to describe adsorption equilibrium, while adsorption kinetics was studied via the Lagergren kinetics model. The SY adsorption onto the MGD was thermodynamically found to be spontaneous (ΔG° < 0) and exothermic (ΔH° = – 19.120 kJ/mol), leading to a decreased disorder (ΔS° = – 54.420 kJ/mol) in the solid–liquid interface. The MGD showed reusability and unique magnetic characteristics. It was concluded that the MGD could be a potential alternative for the adsorptive and magnetic removal of SY from an aqueous solution.

Combat-armored vehicles were equipped with an automatic-fire-extinguishing system to ensure the safety of the crew and vehicle from fires on the vehicle. When a fire was occurred, the automatic-fire-extinguishing system automatically detects the fire through sensors and detection lines, sprays a fire extinguisher, and notifies the crew visually and audibly. Recently, there had been cases of automatic-fire-extinguishing systems malfunction on combat-armored vehicles. In this study, in order to resolve the automatic-fire-extinguisher's malfunction phenomenon, ground noise and inter-circuit noise generated from the fire detection line were identified, and the resistance connected on the circuit was revised to remove noise. As a result of resistance revision, the noises was eliminated and the electromotive force difference between input circuits was made constant, thereby improving the malfunction of the automatic-fire-extinguishing system. By applying the result, it was confirmed that the control device sensed a temperature similar to the actual temperature on actual vehicles, and it was confirmed that the automatic-fire-extinguishing system's malfunction phenomenon was not founded in the field vehicles after then.

This study was performed to evaluate the pollutants removal characteristics of two types of RBFs(Riverbank filtration, Riverbed filtration) intake facilities installed in Nakdong River and in Hwang River respectively. The capacity of each RBF is 45,000 ㎥/d for riverbank filtration intake facility and 3,500 ㎥/d for riverbed filtration intake facility. According to data collected in the riverbank filtration site, removal rate of each pollutant was about BOD(Biochemical oxygen demand) 52%, TOC(Total organic carbon) 57%, SS(Suspended solids) 44%, Total coliforms 99% correspondingly. Furthermore, Microcystins(-LR,-YR,-RR) were not found in riverbank filtered water compared to surface water in Nakdong River. DOC(Dissolved organic carbon) and Humics which are precursors of disinfection byproduct were also reported to be removed about 59% for DOC, 65% for Humics. Based on data analysis in riverbed filtration site in Hwang River, removal rate of each contaminant reaches to BOD 33.3%, TOC 38.5%, SS 38.9%, DOC 22.2%, UV254 21.2%, Total coliforms 73.8% respectively. Additionally, microplastics were also inspected that there was no obvious removal rate in riverbed filtered water compared to surface water in Hwang River.

담관 결석은 폐쇄성 황달, 담도염 및 췌장염 등 합병증을 일으킬 수 있으며, ERCP가 1차 치료로 권유된다. 그러나 ERCP 후 부작용의 발생이 적지 않은 만큼, 이를 최소화하기 위해서는 시술 전 담석의 크기 및 개수, 환자의 출혈성 경향 등 위험인자의 확인이 필요하며, 이에 따른 담석 제거를 위한 적절한 방법이 무엇인지에 이해가 필수적이다. 또한 풍선도관이나 바스켓과 같은 부속기구의 장, 단점 및 적응증 그리고 부작용 대처법에 대해서 충분한 숙지가 필요하다.