Si-based anodes are promising alternatives to graphite owing to their high capacities. However, their practical application is hindered by severe volume expansion during cycling. Herein, we propose employing a carbon support to address this challenge and utilize Si-based anode materials for lithium-ion batteries (LIBs). Specifically, carbon supports with various pore structures were prepared through KOH and NaOH activation of the pitch. In addition, Si was deposited into the carbon support pores via SiH4 chemical vapor deposition (CVD), and to enhance the conductivity and mechanical stability, a carbon coating was applied via CH4 CVD. The electrochemical performance of the C/Si/C composites was assessed, providing insights into their capacity retention rates, cycling stability, rate capability, and lithium-ion diffusion coefficients. Notably, the macrostructure of the carbon support differed significantly depending on the activation agent used. More importantly, the macrostructure of the carbon support significantly affected the Si deposition behavior and enhanced the stability by mitigating the volume expansion of the Si particles. This study elucidated the crucial role of the macrostructure of carbon supports in optimizing Si-based anode materials for LIBs, providing valuable guidance for the design and development of high-performance energy-storage systems.

To improve the lithium-ion battery performance and stability, a conducting polymer, which can simultaneously serve as both a conductive additive and a binder, is introduced into the anode. Water-soluble polyaniline:polystyrene sulfonate (PANI:PSS) can be successfully prepared through chemical oxidative polymerization, and their chemical/mechanical properties are adjusted by varying the molecular weight of PSS. As a conductive additive, the PANI with a conjugated double bond structure is introduced between active materials or between the active material and the current collector to provide fast and short electrical pathways. As a binder, the PSS prevents short circuits through strong π‒π stacking interaction with active material, and it exhibits superior adhesion to the current collector, thereby ensuring the maintenance of stable mechanical properties, even under high-speed charging/discharging conditions. Based on the synergistic effect of the intrinsic properties of PANI and PSS, it is confirmed that the anode with PANI:PSS introduced as a binder has about 1.8 times higher bonding strength (0.4 kgf/20 mm) compared to conventional binders. Moreover, since active materials can be additionally added in place of the generally added conductive additives, the total cell capacity increased by about 12.0%, and improved stability is shown with a capacity retention rate of 99.3% even after 200 cycles at a current rate of 0.2 C.

Once decommissioning begins, it is expected that large amount of radioactive wastes will be produced in a short period of time. The expected amount of radioactive wastes from Kori unit 1 NPP are approximately 80,000 drums (base on 200 L). By minimizing the amount of radioactive wastes generated through decontamination and reduction, KHNP has set the final target for the amount of radioactive wastes to be delivered to the disposal site at approximately 14,500 drums. Here, plasma torch melting technology is an essential technology for radioactive wastes treatment during nuclear power plants decommissioning and operation, because of its large volume reduction effects and the diversity of disposable wastes. KEPCO KPS was able to secure experience in operating Plasma Torch Melter (PTM) by conducting a research service for ‘development of plasma torch melting system advancement technology’ at KHNP-CRI. This study will compare kilo and Mega-Watt class PTM, largely categorized into facility configurations, operating parameters, and waste treatment. Based on this study, it would be desirable to operate PTM with approximate capacity according to the frequency and amount of waste production, and suggest volume for a kilo and Mega-watt class plasma torch in the melting furnace respectively. This plays to its strengths for both a kilo and Mega-watt class PTM.

The thermocatalytic decomposition of methane is a promising method for hydrogen production. To determine the cause of carbonaceous catalyst deactivation and to produce high-value carbon, methane decomposition behavior and deactivated catalysts were analyzed. The surface properties and crystallinity of a commercial activated carbon material, MSP20, used as a methane decomposition catalyst, varied with the reaction time at a reaction temperature of 900 °C. During the initial reaction, MSP20 provided a methane conversion of ≥ 50%; however, the catalyst exhibited rapid deactivation as crystalline carbon grew at surface defects; after 15 min of reaction, approximately 33% methane conversion was maintained. With increasing reaction time, the specific surface area of the catalyst decreased, whereas crystallinity increased. The R-square value of the conversion–crystallinity relationship was significantly higher than that of the conversion–specific surface area relationship; however, neither profile was linear. The activity of the activated carbon catalyst for methane decomposition is mainly determined by the complex actions of the specific surface area and defect sites. The activity was maintained after an initial sharp decline caused by the continuous growth of crystalline carbon product. This study presents the application of carbonaceous catalysts for the decomposition reaction of methane to form COx- free hydrogen, while simultaneously yielding porous carbon materials with an improved electrical conductivity.

KHNP-CRI has developed small-capacity and Mega-Watt Class PTM (Plasma Torch Melter) for the purpose of reducing the volume of radioactive waste and immobilizing or solidifying radioactive materials. About 1 MW PTM is a treatment technology that operates a plasma torch and puts drumshaped waste into a melter and radioactive waste in the form of slag is discharged into a waste container. The small-capacity PTM is a treatment technology that operates a plasma torch and puts small amounts of radioactive waste by directly putting it into the melter through a waste input machine. Mega-Watt Class PTM was able to inject radioactive waste in drums, so it was disposed of without backloging. On the other hand, The small-capacity PTM put radioactive waste without a package, and the waste input was blocked. If even small-capacity PTM put radioactive waste in the form of small packages such as drums, it is expected that various types of radioactive waste can be processed for a long time. Packaging also reduces the risk of radioactive contamination.

In additive manufacturing, the flowability of feedstock particles determines the quality of the parts that are affected by different parameters, including the chemistry and morphology of the powders and particle size distribution. In this study, the microstructures and flowabilities of gas-atomized heat-resistant alloys for additive manufacturing applications are investigated. A KHR45A alloy powder with a composition of Fe-30Cr-40Mn-1.8Nb (wt.%) is fabricated using gas atomization process. The microstructure and effect of powder chemistry and morphology on the flow behavior are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and revolution powder analysis. The results reveal the formation of spherical particles composed of single-phase FCC dendritic structures after gas atomization. SEM observations show variations in the microstructures of the powder particles with different size distributions. Elemental distribution maps, line scans, and high-resolution XPS results indicate the presence of a Si-rich oxide accompanied by Fe, Cr, and Nb metal oxides in the outer layer of the powders. The flowability behavior is found to be induced by the particle size distribution, which can be attributed to the interparticle interactions and friction of particles with different sizes.

The depth of geological disposal of high-level radioactive waste (HLW) varies from country to country, but it is generally considered below 300 m underground. As one of the reliable methods to understand the geological characteristics of these deep areas, the site investigation through drilling is recommended. This paper deals with multidisciplinary research that evaluates the geological characteristics of the site using deep drilling. The deep drilling is 750 m, which is higher than the planned disposal depth. Prior to drilling, literature and surface geological surveys of the target area were conducted, and during drilling, real-time measurement of excavated information for obtaining drilling information, circulating water management and chemical composition through a closed system were monitored. After drilling, field tests such as geophysical borehole logging, deep groundwater sampling, constant pressure injection test, and hydraulic fracturing test were performed. Analysis of the recovered drilling core from a geological point of view such as age dating, rock formation and structural geological analysis, and from geochemical perspectives such as concentration of major/ minor cationic elements, major anions, and trace elements along with the water quality parameters pH, DO, Ec, Eh, etc., from geothermal perspective such as thermal conductivity and coefficient of thermal expansion, from rock mechanical aspects such as physical and mechanical properties of intact rocks and joints, joint distribution, etc. Deep drilling has been completed with 2 holes for granite and 2 holes for sedimentary rocks, and further drilling for gneiss and sedimentary rocks is in progress.

The amount of radioactive waste generated during decommissioning directly affects the disposal cost of waste. Most of the radioactive waste generated is a concrete waste. Therefore reducing the amount of concrete waste can ensure the economic feasibility of the decommissioning project. The activated concrete in a concrete waste can reduce waste only by physical cutting. Therefore it is most important to accurately identify and categorize radionuclides, radioactivity levels, and radioactivity distribution. In the case of radioactive concrete, radiological characteristics are generally evaluated by laboratory analysis after sampling. However it is difficult to apply to all facilities (accelerator & NPP, etc.) because it is a destructive method. Therefore it is necessary to secure verified in-situ measurement technology that can be applied to operational monitoring or decommissioning plans. In this study, the applicability of cyclotron facilities was evaluated based on the evaluation algorithm derived from the Peak to Compton (PTC) method of in-situ measurement technology. And the reliability of the PTC method was verified through qualitative analysis and quantitative analysis. In the case of qualitative analysis, the analysis results of KAERI which has core technology are compared. To this end SAEAN and KAERI conducted field application tests on the front concrete shielding wall of the cyclotron facility at the same time. After removing the background spectrum from the measured spectrum the PTC method was applied to calculate the Q-value for the counting rate in the peak area per counting rate in the Compton continuum area was calculated. As a result the Q-values of SAE-AN and KAERI were 0.52 and 0.24 respectively, and the result of deriving activation distribution(β) by substituting this for the β-Q correlation equation was found that 14.78 and 12.94. As a result of evaluating the activation by the thickness of the shielding wall it was found that 89.1% (SAE-AN) and 91.9% (KAERI) of the total radioactivity were exist at a depth of 5 cm. And it was found that 97.7% and 99.05% of the total radioactivity exists at a depth of 10 cm. The relative error between SAE-AN and KAERI is 1.35%, indicating that the analysis results of the two institutions are highly consistent. A core drill was performed on the concrete shielding wall in the cyclotron facility for the technical verification of the quantitative analysis method. A core sample (6 cm in diameter, 10 cm in depth) was cut to a depth of 2 cm and analyzed in the laboratory. The activation distribution(β) was calculated based on the radioactivity level of each depth sample, and it was found to be 16.99. The relative error between the quantitative analysis and the on-site measurement results was 14.95% confirming that the accuracy is relatively high.

An application of the final decommissioning plan for unit 1 of Kori NPP was submitted to NSSC on 14 May 2021. We have been implementing the project related to the radiological characterization for the plan since 2019. However, the project was not running smoothly due to the regulatory environment. The destructive sampling from the objects was not allowed, so only smear (swipe) samples are available. In this study, the sampling way and the analytical results of radionuclides are presented. In addition, we propose in-situ measurement using gamma camera and in-situ gamma spectroscopy to obtain more comprehensive radiological information on the object.