• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.65.5-66
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• 2017

In the history of astronomy, observed data were interpreted very frequently based upon data measured at laboratories. For example, all the spectroscopic observations were understood via spectroscopic measurements on nuclei, atoms, and molecules. Recently, computational astrophysics plays a role of bridging experimental data to observations, in particular via numerical modeling of complex astronomical phenomena. This presentation focuses on computational nuclear astrophysics that connects experimental data on nuclei to high-energy observation data obtained by X-ray and gamma-ray telescopes. As an example case, X-ray burst will be discussed. In this phenomenon, observed X-ray light curves and spectra can be modeled by stellar evolution calculations that take nuclear reactions of rare isotopes as input information. This presentation also works as an introduction to the following presentation that will provide more detailed discussion on the experimental aspect of X-ray burst.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.186-188
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• 2002

An improved analytical model has been developed to calculate an accurate Bragg curve of proton beam with an arbitrary energy. The model takes the transport of the secondary protons produced by the nuclear inelastic reactions into account. By the model, measured Bragg curves of proton beams with ten energies between 250 and 70 MeV are reproduced well. It will serve to obtain fundamental data for treatment planning and for energy scanning.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.96-99
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• 1992

The microanalysics by the direct observation of 180 (P, a)'" nuclear reactions on tungsten (110) surfaceare investigated using a 2MeV Van de Graaff accelerator. This method allows the determination of very smallquantities of nuclei near the surface of samples. The yields increase with oxygen exposure. The oxygen coverage, 0, is 0.5 at 5 Langmuir and 1.0 at 15 Langmuir.5 Langmuir.

• Journal of the Korean Chemical Society
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• v.24 no.3
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• pp.245-249
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• 1980

Uranium (Ⅵ) was extracted from dilute aqueous solutions of uranyl nitrate with acetylacetone and tri-n-butyl phosphate in n-dodecane. Synergistic effect was observed with the mixed reagents above pH 1. The species extracted are the 1:2:1 and the 1:2:2 uranyl-AA-TBP complexes. The extraction constants for these reactions have been determined.

• Nuclear Engineering and Technology
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• v.6 no.1
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• pp.23-26
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• 1974

The rates and activation parameters for the halide exchange reactions of methanesulfonyl chloride in dry acetone, acetonitrile, and methanol have been determined. It was found that nucleophilic order is Cl->Br->I-. The rate of chloride exchange with methanesulfonyl chloride decreases in the order of solvent; ($CH_3$)$_2$CO>$CH_3$CN》MeOH. Results are intrpreted in terms of easiness of the initial state desolvation and solvation stabilization of the transition state.

• Nuclear Engineering and Technology
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• v.38 no.8
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• pp.733-752
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• 2006

Severe accidents in PWRs are characterized by a continuously changing geometry of the core due to chemical reactions, melting and mechanical failure of the rods and other structures. These local variations of the porosity and other parameters lead to multi-dimensionnal flows and heat transfers. In this paper, a comprehensive set of multi-dimensionnal models describing heat transfers, thermal-hydraulics and melt relocation in a reactor vessel is presented. Those models are suitable for the core description during a severe accident transient. A series of applications at the reactor scale shows the benefits of using such models.

• Nuclear Engineering and Technology
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• v.36 no.5
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• pp.375-387
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• 2004

This paper presents a transient multicomponent mixture analysis tool developed to analyze the molecular diffusion, natural convection, and chemical reactions related to air ingress phenomena that occur during a primary-pipe rupture of a high temperature gas-cooled reactor (HIGR). The present analysis tool solves the one-dimensional basic equations for continuity, momentum, energy of the gas mixture, and the mass of each gas species. In order to obtain numerically stable and fast computations, the implicit continuous Eulerian scheme is adopted to solve the governing equations in a strongly coupled manner. Two types of benchmark calculations were performed with the data of prerious Japanese inverse U-tube experiments. The analysis program, based on the ICE technique, runs about 36 times faster than the FLUENT6 for the simulation of the two experiments. The calculation results are within a 10% deviation from the experimental data regarding the concentrations of the gas species and the onset times of natural convection.

• Nuclear Engineering and Technology
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• v.50 no.7
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• pp.1184-1189
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• 2018

Pyroprocessing uses various molten salts during electrochemical unit processes. Reaction products after the electrochemical processes must contain a significant amount of residual salts to be separated. Vacuum distillation is a common method to separate the residual salts; however, its high operation temperature may cause side reactions. In this study, a simple rotation technique using centrifugal force was suggested to separate the residual salts from the reaction products at relatively low temperature compared to the distillation technique. When a reaction product container with porous wall rotates inside a vessel heated above the melting point of the residual salt, the residual salt in the liquid phase is separated through centrifugal force. It was shown that the $LiNO_3-Al_2O_3$ mixture can be separated by this technique to leave solid $Al_2O_3$ inside the container, with a separation efficiency of 99.4%.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.170-175
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• 2019

Displacement cross-sections for an advanced assessment of radiation damage rates were obtained for a number of materials using the arc-dpa model at neutron incident energies from $10^{-5}eV$ to 10 GeV. Evaluated data files, CEM03 and ECIS codes, and an approximate approach were applied for the calculation of recoil energy distributions in neutron induced reactions. Three sets of displacement cross-sections based on the use of low-energy data from JEFF-3.3, ENDF/B-VIII.0, and JENDL-4.0u were prepared. Files contain also cross-sections calculated using the standard NRT model. Special efforts were made to estimate the uncertainty of obtained displacement cross-sections.

• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1777-1780
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• 2024

Chemical and thermal characteristics of cation exchange resins were examined after irradiation of gamma rays. The degradation of cation exchange resins was mainly observed at doses of up to 500 kGy, whereas the balance between degradation and cross-linking reactions was sustained at 700 kGy. While the carbon content decreased significantly up to a maximum dose of 500 kGy, it showed an increase at higher doses. Conversely, the oxygen content exhibited a decrease in contrast to the carbon content. The continuous reduction in sulfur content was attributed to the decomposition of sulfonic groups. Gamma-ray irradiation caused a decrease in the initiation temperature of sulfonic groups and PS-DVB, but unlike the chemical properties of cation exchange resins due to gamma-ray irradiation, the thermal properties of resins remained unaffected.