[en] Research reactor fuel is manufactured as a dispersed fuel by mixing metal powder and uranium alloy powder in order to efficiently release heat by nuclear fission. Due to the mixing characteristics of dissimilar powders, non-uniform mixing such as segregation is likely to occur, and there is a limit to the uranium loading density because the base material must be contained at least 50 vol.%. In this study, a research on the manufacturing technology was conducted to dramatically improve the uranium homogeneity and loading density by directly coating the matrix material on the uranium alloy powder. A stirring device for spherical powder coating that can be used in the PVD method was designed and manufactured, and Al coating process was established through optimization of process parameters. Al homogeneous coating layer having a thickness of 10 µm or more was prepared and analyzed for its characteristics. Using Al-coated U-7 wt.%Mo powder, it was developed in an efficient dispersion fuel manufacturing technology consisting of a powder-extrusion process to produce a dispersion fuel at the level of a test piece. The uranium loading density was about 12 gU/cm³, exceeding the existing manufacturing limit of dispersed fuel by more than 50%, and a semi-perfect dispersion fuel was manufactured with a homogeneity within ±2%. Through additional research, we have completed the commercialization of uranium ultra-high density and semi-perfect homogeneous dispersion fuel manufacturing technology, and will contribute to strengthening export competitiveness through research reactor and nuclear fuel

[en] The aim of this study was to investigate effects of hafnium content on the corrosion behavior of Ti alloys in electrolyte containing chloride ion. For this study, Ti-Hf binary alloys contained 10 wt%, 20 wt% and 30 wt% Hf were manufactured in a vacuum arc-melting furnace and subjected to heat treatment for 12h at 1000 .deg. C in an argon atmosphere. The pitting corrosion behavior of the specimens was examined through potentiodynamic and potentiostatic tests in 0.9 wt% NaCl electrolyte at 36.5 ± 1 .deg. C. The corrosion morphology of Ti-xHf alloys was investigated using optical microscopy (OM) and X-ray diffractometer (XRD). From the optical microstructures and XRD results, needle-like martensite (α') phases of the Ti-xHf alloys increased with an increase of Hf addition. Corrosion current density (I_corr) and current density (I_300mV) in passive region decreased, whereas, corrosion potential increased with Hf content. At the constant potential (300 mV_SCE), current density decreased as time increased

[en] This paper describes the probabilistic analysis of generating cost results in the final of the process of the APR+ standard detailed design. In this simulation, the results of the generating cost (COE, Cost of Electricity) of APR+ dual unit were determined using the probability cost analysis technique, the COE range was shown to be 39.60 won/kWh∼52.82 won/kWh. As a part of a national long-term R and D program, the Advanced Power Reactor plus (APR+) project was launched in 2007. The APR+ project consists of three phases. In the first phase, the basic design was developed. the second phase involves the development of the standard detailed design and the submittal of the request for Standard Design Approval (SDA) to the Korean nuclear regulatory body. The third phase is the completion of the APR+ design optimizing core part

[en] In this study, we fabricated and characterized a UV-curable plastic scintillation resin for 3D printing technology. The resin for 3D printing was prepared by using the co-polymers MMA (methyl meta-acrylate, DHPA (dipentaerythritol hexa-acrylate), naphthalene and PPO (2,5- diphenyloxazole) organic scintillator obtained from Sigma Aldrich. Irgacure 184 (BASF Co.) was used as a photo-initiator. Protons and X-ray-induced luminescence spectra of the UV-cured plastic scintillator were measured. For the emission spectrum, QE65000 and USB4000 optic spectrometers (Ocean Optics) were used. The cured plastic scintillator showed an emission spectrum at wavelength between 380 and 650 nm, peaking at 405 nm and 550 nm, excited by using 100 MeV proton. The observed emission matched well with the quantum efficiency curve of the photodiode. The result showed that the scintillator provided the possibility of adding 3D printing technology, and applications can be found in human dosimetry, etc.

[en] How to fabricate metal nanoparticles decorated on CRTs? They are chemical functionalization, defect induced loading and thermal evaporation. MeV electron beam irradiation are an easy method for decorating MWCNTs with size-homogeneous metal NPs and a universal method for obtaining any metal NPs on MWCNTs if the metal form a compound with Cl

[en] High-density U-Mo alloys are regarded as promising candidates for advanced research reactor fuel as they have shown stable irradiation performance when compared to other uranium alloys and compounds. However, interaction layer formation between the U-Mo alloys and Al matrix degrades the irradiation performance of U-Mo Dispersion fuel. Therefore, the addition of Ti in U-Mo alloys, the addition of Si in a Al matrix, and silicide or nitride coating on the surface of U-Mo particles have been proposed to inhibit the interaction layer growth. In this study, U-Mo alloy powder was produced using a centrifugal atomization method. In addition, silicide coating layers were fabricated by several mixing process changes on the surface of the U-Mo particles. The coated powders were characterized by using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDAX). Decreased annealing duration did not affect the forming of silicide coating layers on the surface of U-7wt%Mo powders. The variation in the mixing ratio between U-7wt%Mo and Si powders had an effect on the quality of silicide coating on the U-7wt%Mo powders. The weight of Si powders should be smaller than that of U-7wt%Mo powders for better silicide coating when it comes to the mixing ratio

[en] The excessive interaction between the U-Mo alloys and their surrounding Al matrix lead to excessive local swelling called 'pillowing'. For this reason, KAERI suggested several remedies such as alloying U-Mo with Ti, or Al matrix with Si. In addition, silicide or nitride coatings on the surface of U-Mo particles have also been proposed to hinder the growth of the interaction layer. In this study, centrifugally atomized U-Mo-Ti alloy powders were coated with silicide layers. The coating process was improved when compared to the previous coating in terms of the ball milling and heat treatment conditions. Subsequently, silicide coated U-Mo-Ti powders and pure aluminum powders were mixed and made into a compact for the annealing test. The compacts were annealed at 550 .deg. C for 2hr, and characterized using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). 1. Uniform, homogeneous, thickness controllable silicide layers were successfully coated on the surface of U-7wt%Mo-1wt%Ti powders. 2. U₃Si, U₃Si₂ silicide layers formed on the surface of U-7wt%Mo-1wt%Ti powders, and were identified by XRD and EDS analyses

[en] We report a simple technique for direct neutron spectroscopy using pure LaCl₃ crystals. Pure LaCl₃ crystals exhibit considerably better pulse shape discrimination (PSD) capabilities with relatively good energy resolution as compared with Ce-doped LaCl₃ crystals. Single crystals of pure and Ce-doped LaCl₃ were grown using an inhouse-developed Bridgman furnace. PSD capabilities of these crystals were investigated using ²⁴¹Am and ¹³⁷Cs sources. Fast neutron detection was tested using a²⁵²Cf source and three separate bands corresponding to electron, proton, and alpha were observed. The proton band induced by the ³⁵Cl(n,p)³⁵S reaction can be used for direct neutron spectroscopy because proton energy is proportional to incident neutron energy. Owing to good scintillation performance and excellent PSD capabilities, pure LaCl₃ is a promising candidate for space detectors and other applications that necessitate gamma/fast neutron discrimination capability

[en] In this study, continuous in-source hydrogen/deuterium exchange (HDX) atmospheric pressure photoionization (APPI) mass spectrometry (MS) with continuous feeding of D₂O was developed and validated. D₂O was continuously fed using a capillary line placed on the center of a metal plate positioned between the UV lamp and nebulizer. The proposed system overcomes the limitations of previously reported APPI HDX-MS approaches where deuterated solvents were premixed with sample solutions before ionization. This is particularly important for APPI because solvent composition can greatly influence ionization efficiency as well as the solubility of analytes. The experimental parameters for APPI HDX-MS with continuous feeding of D₂O were optimized, and the optimized conditions were applied for the analysis of nitrogen-, oxygen-, and sulfur-containing compounds. The developed method was also applied for the analysis of the polar fraction of a petroleum sample. Thus, the data presented in this study clearly show that the proposed HDX approach can serve as an effective analytical tool for the structural analysis of complex mixtures. .

[en] We demonstrate the formation of silicide coating layers, U₃Si₅, U₃Si₂ and U₃MoSi₂, on the surface of U-7Mo and U-7Mo-1Ti powders using the pack cementation method, and the suppression of Al diffusion into the U kernel by the U₃MoSi₂ layer. The observation for the Ti addition provided that could explain the prevention of Si diffusion into the grain boundary of U-7Mo kernel by the formation of Ti-rich layer, whereas Si diffused along the grain boundary of U-7Mo kernel without the Ti addition on U-7Mo. In this sense, Al diffusion into the core of U-7Mo-1Ti was interrupted by U₃MoSi₂, and it could be concluded that the effect of U₃MoSi₂ phase as a diffusion barrier for Al is valid for the annealing at 873 K for 2 hr. There is no higher temperature process in regard of the fabrication of nuclear fuel, thus U₃MoSi₂ can be a possible candidate for the surface engineering of U-Mo alloy powders.