• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.671-671
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• 2004

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.785-794
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• 2016

The Argonne National Laboratory of the United States and the Kharkov Institute of Physics and Technology of the Ukraine have been collaborating on the design, development and construction of a neutron source facility at Kharkov Institute of Physics and Technology utilizing an electron-accelerator-driven subcritical assembly. The electron beam power is 100 kW using 100-MeV electrons. The facility was designed to perform basic and applied nuclear research, produce medical isotopes, and train nuclear specialists. The biological shield of the accelerator building was designed to reduce the biological dose to less than 5.0e-03 mSv/h during operation. The main source of the biological dose for the accelerator building is the photons and neutrons generated from different interactions of leaked electrons from the electron gun and the accelerator sections with the surrounding components and materials. The Monte Carlo N-particle extended code (MCNPX) was used for the shielding calculations because of its capability to perform electron-, photon-, and neutron-coupled transport simulations. The photon dose was tallied using the MCNPX calculation, starting with the leaked electrons. However, it is difficult to accurately tally the neutron dose directly from the leaked electrons. The neutron yield per electron from the interactions with the surrounding components is very small, ~0.01 neutron for 100-MeV electron and even smaller for lower-energy electrons. This causes difficulties for the Monte Carlo analyses and consumes tremendous computation resources for tallying the neutron dose outside the shield boundary with an acceptable accuracy. To avoid these difficulties, the SOURCE and TALLYX user subroutines of MCNPX were utilized for this study. The generated neutrons were banked, together with all related parameters, for a subsequent MCNPX calculation to obtain the neutron dose. The weight windows variance reduction technique was also utilized for both neutron and photon dose calculations. Two shielding materials, heavy concrete and ordinary concrete, were considered for the shield design. The main goal is to maintain the total dose outside the shield boundary less than 5.0e-03 mSv/h during operation. The shield configuration and parameters of the accelerator building were determined and are presented in this paper.

• Bulletin of the Korean Chemical Society
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• 제27권11호
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• pp.1752-1756
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• 2006

This study explores and interprets in a new way the complex solvent and the temperature dependence of the NMR shifts for the N-$CH_2$ protons in tris(N,N-diethyldithiocarbamato) iron(III) in acetone, benzene, carbon disulfide, chloroform, dimethylformamide and pyridine. The NMR shifts are interpreted in terms of the Fermi contact interaction and the dipolar term from the multipole expansion of the interaction of the electron orbital angular momentum and the electron spin dipolar-nuclear spin angular momentum. This analysis yields a direct measure of the effect of the solvent system on the environment of the transition metal ion. The results are analysed in terms of the crystal field environment of the transition metal ion with contributions from (a) the dithiocarbamate ligand (b) the solvent molecules and (c) the interaction of the effective dipole moment of the polar solvent molecule with the transition metal ion complex.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.229-237
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• 2023

The mechanics underlying photon and electron interactions was validated using our developed Brachytherapy computer code for high Dose Rate (HDR). By comparing the photon cross-section utilizing multiple physics libraries in the developed code, the results were benchmarked against experimental and theoretical findings. Klein-Nishina and experimental cross-section results were in good agreement with the Livermore library results. For two therapeutically relevant materials, the first scattered electron range was measured within 1 mm and 2 mm, which has significant implications for the interpretation of the kernel dose spikes observed in previous research.

• Bulletin of the Korean Chemical Society
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• 제5권3호
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• pp.93-97
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• 1984

A general expression using the nonmultipole expansion method is derived for the NMR shift arising from 3d electron angular momentum and the 3d electron spin dipolar-nuclear spin angular momentum interactions for a 3$d^2$ system in a strong crystal field environment of octahedral symmetry when the threefold axis is chosen as the quantization axis. The NMR shift is separated to the contribution of constant, $1/R^5\;and\;1/R^7$ terms and compared with the multipolar terms. We find that $1/R^5$ term contributes dominantly to the NMR shift but the contribution of $1/R^7$ term may not be negligible. It is also found that the exact values of the NMR shift are in agreement with the multipolar results for distances larger than 0.35 nm.

• Bulletin of the Korean Chemical Society
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• 제18권4호
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• pp.424-427
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• 1997

To study the NMR chemical shift arising from the 5f-electron orbital angular momentum and the 5f-electron spin dipolar-nuclear spin angular momentum interactions, the evaluation of the hyperfine integrals has been extended to any pairs of SCF type 5f orbitals adopting a general method which is applicable to a general vector R, pointing in any direction in space. From the electronic wavefunctions for 5f orbitals expressed in common coordinate system, the radial part of the hyperfine interaction integrals are derived by translating the exponential part, r2 exp(-2βr), in terms of R, rN and the modified Bessel functions. The radial integals for 5f orbitals are tabulated in analytical forms. When two of the hyperfine integrals along the (100), (010), (001), (110), and (111) axes are calculated using the derived radial integrals, the calculated values for the 5f system change sign for R-values larger than R　0.35 nm. But the calculated values for the 4f systems change sign for R-values larger than R　0.20 nm.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.915-922
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• 2018

Metallic fuel has been considered for sodium-cooled fast reactors because it can maximize the uranium resources. It generates rare earth elements as fission products, where it is reported by aggravating the fuel-cladding chemical interaction at the operating temperature. Rare earth elements form a multicomponent alloy (Ce-Nd-Pr-La-Sm-etc.) during reactor operation, where it shows a higher reaction thickness than a single element. Experiments have been carried out by simplifying multicomponent alloys for mono or binary systems because complex alloys have difficulty in the analysis. In previous experiments, xCe-yNd was fabricated with two elements, Ce and Nd, which have a major effect on the fuel-cladding chemical interaction, and the thickness of the reaction layer reached maximum when the rare earth elements ratio was 1:1. The objective of this study is to evaluate the effect and relationship of rare earth elements on such synergistic behavior. Single and binary rare earth model alloys were prepared by selecting five rare earth elements (Ce, Nd, Pr, La, and Sm). In the single system, Nd and Pr behaviors were close to diffusion, and Ce showed a eutectic reaction. In the binary system, Ce and Sm further increased the reaction layer, and La showed a non-synergy effect.

• Bulletin of the Korean Chemical Society
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• 제4권3호
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• pp.103-114
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• 1983

The NMR shift arising from the electron angular momentum and the electron spin dipolar-nuclear spin angular momentum interaction has been examined for a $3d_1$ system in a strong octahedral crystal field when the threefold axis is chosen as the quantization axis. To investigate the NMR shift in this situation, first, we have extended the evaluation of the hyperfine integrals to any pairs of 3d orbitals adopting a general method which is applicable to a general vector R, pointing in arbitrary direction in space. Secondly, a general expression using a nonmultipole technique is derived for the NMR shift resulting from the electron angular momentum and the electron spin dipolar-nuclear spin angular momentum interactions. From this expression all the multipolar terms are determined. ${\Delta}B/B$ for the $3d_1$ system in this case is compared with that for the 3d1 system when the z axis is chosen as the quantization axis. When we choose the threefold axis as the quantization axis, it is found that along the , and axes, ${\Delta}B/B$ values are significantly different from each other and along the , <-1-1-1>, <-11-1>, , <-1-11>, , and <-111> axes, ${\Delta}B/B$ values are however the same. We also find that the 1/R7 term contributes dominantly to the NMR shift for all values of R. When 1/$R^5$ term is included, there is good agreement between the exact solution and the multipolar terms when $R\; {\leqslant}\;0.35\;nm.$.

• Bulletin of the Korean Chemical Society
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• 제7권3호
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• pp.170-178
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• 1986

The NMR chemical shift arising from 4d electron angular momentum and 4d electron angular momentum and 4d electron spin dipolar-nuclear spin angular momentum interactions for a $4d^1$ system in a strong crystal field environment of trigonal symmetry, when the threefold axis is chosen to be the axis of quantization axis, has been examined. A general expression using the nonmultipole expansion method (exact method) is derived for the NMR chemical shift. From this expression all the multipolar terms are determined. We observe that along the (100), (010), (110), and (111) axes the NMR chemical shifts are positive while along the (001) axis, it is negative. We observe that the dipolar term (1/R3) is the dominant contribution to the NMR chemical shift except for along the (111) axis. A comparison of the multipolar terms with the exact values shows also that the multipolar results are exactly in agreement with the exact values around $R{\geqslant}0.2$ nm. The temperature dependence analysis on the NMR chemical shifts may imply that along the (111) axis the contribution to the NMR chemical shift is dominantly pseudo contact interaction. Separation of the contributions of the Fermi and the pseudo contact interactions would correctly imply that the dipolar interaction is the dominant contribution to the NMR chemical shifts along the (100), (010), (001), and (110) axes, but along the (111) axis the Fermi contact interaction is incorrectly the dominant contribution to the NMR chemical shift.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2613-2620
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• 2023

Excellent thermal neutron absorption performance of boron expands the potential use of boron rich slag to prepare epoxy resin matrix nuclear shielding composites. However, shielding attenuation behaviors and mechanism of the composites against gamma rays are unclear. Based on the radiation protection theory, Phy-X/PSD, XCOM, and ⁶⁰Co gamma ray source were integrated to obtain the shielding parameters of boron rich slag/epoxy resin composites at 0.015-15 MeV, which include mass attenuation coefficient (µ_t), linear attenuation coefficient (µ), half value thickness layer (HVL), electron density (N_eff), effective atomic number (Z_eff), exposure buildup factor (EBF) and exposure absorption buildup factor (EABF).µ_t, µ, HVL, N_eff, Z_eff, EBF and EABF are 0.02-7 cm²/g, 0.04-17 cm^-1, 0.045-20 cm, 5-14, 3 × 10²³-8 × 10²³ electron/g, 0-2000, and 0-3500. Shielding performance is BS4, BS3, BS3, BS1 in descending order, but worse than ordinary concrete. µ and HVL of BS1-BS4 for ⁶⁰Co gamma ray is 0.095-0.110 cm^-1 and 6.3-7.2 cm. Shielding mechanism is main interactions for attenuation gamma ray by BS1-BS4 are elements with higher content or higher atomic number via Photoelectric Absorption at low energy range, and elements with higher content via Compton Scattering and Pair Production in Nuclear Field at middle and higher energy range.