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[en] Technology standard for shipping containers of radioactive materials becomes strict by IAEA Regulation 'regulations for the safe transport of radioactive material ST-1' and the domestic regulations. Development of the RI shielding casks having high efficiency is needed. To design a mold for casting the shielding cask, computer simulation was introduced. Purpose of this study is to investigate optimum casting conditions for manufacturing a sound shipping container without defects by the melt filling and solidification analysis using computer code Z-cast. As a result of analysis, although two molds have the same temperature gradient, the mold having higher temperature could reduce the shrinkage defects of a product. When there is no temperature gradient in mold whose riser size is 60mm or 70mm respectively, the shrinkage defects existed in the casting. The temperature gradient of a mold is needed to make a sound product without shrinkage defects. When we are going to reduce the shrinkage defects, the riser size and temperature gradient of the mold is more effective factor than the melting temperature
[en] We report the first observation of infrared emission from a gaseous ionic polycyclic aromatic hydrocarbon (PAH), the pyrene cation, over the range of wavelengths spanned by the ubiquitous interstellar unidentified infrared emission bands (UIRs). The complete set of pyrene cation IR emissions is observed, with relative intensities consistent with astrophysical observations, supporting the proposal that ionized PAHs are major contributors to the UIR bands. Additionally, unidentified features possibly arising from dehydrogenated PAH species are noted in the spectrum
[en] Technical part Li ion battery market is explosively growing in the world. And then, the acquisition of technologies and patents for Li ion batteries is considered as one of the important issues in the world. Economical/Industrial parts Li ion batteries have been considered as the best candidate of energy storage system for large scale application such as electric vehicles as well as small devices such as cellular phones. It is expected that Li ion battery market size grows dramatically each year. Ⅲ. Scope and Contents of Project 1. Research scope The structural information of electrode materials for ion batteries is calculated using Rietveld refinement with neutron/X-ray diffraction. Their thermal stability is measured using in situ high temperature X-ray diffraction. Ⅳ. Result of Project 1. Research results Using Rietveld refinement with neutron diffraction, we calculated Li-Ni site mixing in NCM 811 which is well known as one of the best cathode materials for Li ion batteries. Maximum entropy method (MEM) showed us the possibility of fast Li diffusion in NCM 811. And, we developed a novel cathode material Na7V3(P2O7)4 with high operation potential and excellent cyclability for the first time using Rietveld refinement with neutron/X-ray diffraction and first principle calculation.
[en] There are two final goals we aspire to reach: 1. Development of strong candidates of ultra high burn-up fuel pellets for a PCI (pellet-cladding interaction) remedy. · More than 30% rise in creep deformation property. 2. Development of fabrication technology of annular fuel pellet. ο Commercial cylindrical fuel pellet levels of annular pellet. The developed technology for the high plasticity fuel pellet can be used to reduce the PCI in the annular pellet for the dual cooled fuel. The annular pellet with high plasticity could be an essential component of the dual cooled fuel. Our fabrication technology for the annular pellet with high precision can be one of the most important core technology for actualizing the dual cooled fuel. It could be enable us to hold a dominant position in the fields of power uprating of PWRs. Developed measuring and evaluation technology for out of pile properties of nuclear fuel pellet can be used by the industry in product qualification analysis fields
[en] This study covered the following scopes : analysis of Japan's policy trend on the development and utilization of nuclear energy, international and domestic viewpoint of Japan's nuclear weapon capability, Japan's foreign affairs and international cooperation, status of Japan's nuclear technology development and its level, status and level of nuclear core technologies such as nuclear reactor and related fuel cycle technologies. Japan secures the whole spectrum of nuclear technologies including core technologies through the active implementation of nuclear policy for the peaceful uses of nuclear energy during the past five decades. Futhermore, as the result of the active cultivation of nuclear industry, Japan has most nuclear-related facilities and highly advanced nuclear industrial technologies. Therefore, it is reasonable that Japan might be recognized as one of countries having capability to get nuclear capability in several months
[en] Neighbouring countries surrounding Korean Peninsula, which are the US, China, Russia, Japan and Taiwan, are all the nuclear countries. Some of the neighbouring countries, the US, China and Russia, are nuclear weapon states as well as the nuclear peaceful use countries. Other countries, Japan and Taiwan are not the nuclear weapon states but keep the high level of nuclear energy technologies. Meanwhile, Korea is recognized as the country of which peaceful activities for nuclear energy utilization are much more vigorous. Therefore, Korean national policies on politics, diplomacy and defense may be highly possible to be impacted on by nuclear policies of the neighbouring countries. This study defined the neighbouring countries as those which have politically or economically a direct or indirect relationship with Korea. And then, nuclear capabilities of the neighbouring countries and their impacts on our national security were analyzed in terms of nuclear techniques. Defensive response is technically most probable measure against nuclear threats and terrors. It include the establishment of national nuclear emergency response system as well as the development of environmental radiation protection, decontamination and environment recovering technology. Finally, it was suggested that a cooperation agency of enhancing the development of dual-use technologies be located at a science and technology complex
[en] In this paper, the axial force of high tension bolt is measured by using ultrasonic wave. In the case of the different materials the conclusion obtained are as follows : (1) The relation of the material quality of each high tension bolt and form(diameter or section area), and yield axial force can be observed. (2) As 0.1 is divided by the apparent elongation the measurement accuracy of high tension bolt can be archived. Also, it is founded that the Joint axial force of high tension bolt is determined by the yield force
[en] Plasma-facing components (PFCs) in fusion devices inherently suffer from irradiation by hydrogen isotope plasmas. Graphite is used as the first wall of the Korea Superconducting Tokamak Advanced Research (KSTAR) because of its low atomic number and excellent thermal and mechanical properties. In this experiment, the effect of hydrogen-plasma irradiation on the PFCs was studied using KSTAR-like graphite tiles. The tiles were irradiated with low-energy hydrogen plasmas produced by an electron cyclotron resonance system. The changes in the surface morphology and disorders induced in the structure were investigated using field-emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and electron spin resonance measurements.
[en] The first wall of the Korea Superconducting Tokamak Advanced Research (KSTAR) is covered with graphite tiles. KSTAR-like graphite was fabricated as samples with a dimension of 10 × 10 × 1 mm3, and the samples were irradiated with 100-eV deuterium plasmas by using an electron cyclotron resonance system. Irradiations were performed for 30 min and 120 min under a 2.77 × 1021 m−2s −1 particle flux; irradiations for 30 min and 120 min had equivalent fluences of 4.99 × 1024 m−2 and 1.99 × 1025 m−2, respectively. Changes in the surface morphology due to the irradiation were examined with field-emission scanning electron microscopy. In addition, deuterium gas desorbed from the samples was investigated by using a thermal desorption spectroscopy system, where the samples were linearly heated from 550 K to 1100 K at a constant ramp rate of 0.1 K/s or 0.3 K/s.
[en] Alloys of Fe-25Cr, Fe-14Al and Fe-25Cr-6Al have been exposed isothermally to an equilibriated gas mixture of 94.9% H2/1.1% H2S/4% H2O and 69.2% H2/0.8% H2S/30% H2O at 1143K. Severe corrosion of Fe-25Cr alloy in both environments by the formation of non-protective Fe-rich sulfide in the outer layer of scale and Cr-rich sulfide in the inner layer of scale has been observed. Preferential sulfidation of iron and chromium of Fe-25Cr-6Al alloy in both environments enriched aluminium at the alloy/scale interface and reduced the corrosion rate of Fe-25Cr-6Al alloy compared to Fe-25Cr alloy. A complete and dense Al2O3 rich layer of scale is able to form on Fe-14Al alloy in both environments and protects the alloy from extensive corrosion for the 7 hours test period. However the scales showed a propensity toward a scale spallation due to thermal expansion mismatch stresses for the long hour period