• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3478-3487
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• 2022

In this study, we incorporate an anisotropic scattering scheme involving spherical harmonics into the method of characteristics (MOC). The neutron transport solution in a light water reactor can be significantly improved because of the impact of an anisotropic scattering source with the MOC flat source approximation. Several problems are selected to verify the proposed scheme and investigate its effects and accuracy. The MOC anisotropic scattering source is based on the expansion of spherical harmonics with Legendre polynomial functions. The angular flux, scattering source, and cross section are expanded in terms of the surface spherical harmonics. Later, the polynomial is expanded to achieve the odd and even parity of the source components. Ultimately, the MOC angular and scalar fluxes are calculated from a combination of two sources. This paper presents various numerical examples that represent the hot and cold conditions of a reactor core with boron concentration, burnable absorbers, and control rod materials, with and without a reflector or baffle. Moreover, a small critical core problem is considered which involves significant neutron leakage at room temperature. We demonstrate that an anisotropic scattering source significantly improves solution accuracy for the small core high-leakage problem, as well as for practical large core analyses.

• Journal of the Korean institute of surface engineering
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• v.49 no.2
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• pp.111-118
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• 2016

A method to quantitatively analyze the defects formed by the hydrogen evolution during electroplating was suggested based on the theoretical approach of the small angle neutron scattering technique. In case of trivalent chrome layers, an isolated defect size due to the hydrogen evolution was about 40 nm. Direct and pulse plating conditions gave the average defect size of about 4.9 and $4.5{\mu}m$ with rod or calabash shape, respectively. Current density change of the pulse plating from $1.5A/dm^2$ to $2.0A/dm^2$ enlarged the average defect size from 3.3 to $7.8{\mu}m$. The defect morphology like rod or calabash was originated by inter-connecting the isolated defects. Small angle neutron scattering was useful to quantitatively evaluate defect morphology of the deposit.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1277-1281
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• 2020

A novel ceramic Gas Electron Multiplier (GEM) has been developed to meet the demand of high counting rate for the neutron detection which is an alternative to ³He-based detector at China Spallation Neutron Source (CSNS). An experiment was performed to measure the neutron transmittance of ceramic-GEM and FR4-GEM at the small angle neutron scattering (SANS) instrument. The result showed the ceramic-GEM has higher transmittance and less self-scattering especially for cold neutrons. One single ceramic GEM could give a gain of 10²-10⁴ in the mixture gas of Ar and CO₂ (90%:10%) and its energy resolution was about 27.7% by using ⁵⁵Fe X ray of 5.9 keV. A prototype has been developed in order to investigate the performances of the ceramic GEM-based neutron detector. Several neutron beam tests, including detection efficiency, spatial resolution, two-dimensional imaging, and wavelength spectrum, were carried out at CSNS and China Mianyang Research Reactor (CMRR). The results show that the ceramic GEM-based neutron detector is a good candidate to measure the high intensity neutrons.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.1917-1925
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• 2020

New versions of ENDF/B and JEFF data libraries have been released during the past two years with significant updates in the neutron reaction sublibrary and the thermal neutron scattering sublibrary. In order to get a more comprehensive impression of the criticality quality of these two latest neutron data libraries, and to provide reference for the selection of the evaluated nuclear data libraries for the science and engineering applications of the Reactor Monte Carlo code RMC, the criticality benchmarking of the two latest neutron data libraries has been performed. RMC was employed as the computational tools, whose processing capability for the continuous representation ENDF/B-VIII.0 thermal neutron scattering laws was developed. The RMC criticality validation suite consisting of 116 benchmarks was established for the benchmarking work. The latest ACE format data libraries of the neutron reaction and the thermal neutron scattering laws for ENDF/B-VIII.0, ENDF/B-VII.1, and JEFF-3.3 were downloaded from the corresponding official sites. The ENDF/B-VII.0 data library was also employed to provide code-to-code validation for RMC. All the calculations for the four different data libraries were performed by using a parallel version of RMC, and all the calculated standard deviations are lower than 30pcm. Comprehensive analyses including the C/E values with uncertainties, the δk/σ values, and the metrics of χ² and < |Δ| >, were conducted and presented. The calculated keff eigenvalues based on the four data libraries generally agree well with the benchmark evaluations for most cases. Among the 116 criticality benchmarks, the numbers of the calculated keff eigenvalues which agree with the benchmark evaluations within 3σ interval (with a confidence level of 99.6%) are 107, 109, 112, and 113 for ENDF/B-VII.0, ENDF/B-VII.1, ENDF/B-VIII.0 and JEFF-3.3, respectively. The present results indicate that the ENDF/B-VIII.0 neutron data library has a better performance on average.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.787-788
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• 2005

• Journal of the Korean Vacuum Society
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• v.14 no.3
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• pp.126-131
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• 2005

Small-angle neutron scattering (SANS) is a very powerful techniques for nanostructure characterization. In this paper, we report the conceptual design and technical description of the 40 in small angle neutron scattering (SANS) insoument which is being developed by KAIST and KAERI for installation at 30 MW HANARO research reactor. For the optimal design of 40 m SANS, a series of computer simulation were pe.to.mod. The Q-.ange of the 40m SANS inst.ument is $0.0005\;\AA^{-1}-1.0\AA^{-1}$ which is a world top-class SANS Q-range. When the cold neutron spectrum used in the simulation is realized, the neutron flux at sample position is expected to be comparable to the current state-of-art SANS instrument in the world.

• Nuclear Engineering and Technology
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• v.31 no.6
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• pp.631-637
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• 1999

The module LEAPR of NJOY data processing system has been improved to have the capability of computing the thermal elastic scattering cross sections for silicon, which has a diamond-like structure. Silicon lattice was assumed as an fcc lattice with two atoms at each lattice point. The calculation formulas for thermal neutron elastic scattering by silicon were introduced and incorporated into LEAPR, and then the scattering cross sections for silicon were computed. The results were compared with experimental data, and they were found to give a good agreement with experimental data.

• Nuclear Engineering and Technology
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• v.43 no.1
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• pp.7-12
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• 2011

In this paper we review the neutron scattering work performed on 3 different antiferromagnetic pyrochlores which reveal how the character of the magnetic interactions plays a major role on the eventual outcome of the magnetic ground state. $Tb_2Ti_2O_7$, $Er_2Ti_2O_7$ and $Y_2Mo_2O_7$ have all been extensively studied over the past 15 years and are known to display, respectively, spin liquid, long range ordered and glassy ground states. Although detailed experiments have been performed on these compounds, and much is known about their low temperature properties, a detailed theoretical understanding of their ground states remains elusive.

• Journal of the Korean institute of surface engineering
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• v.37 no.3
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• pp.175-178
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• 2004

The size and number of nano-size defects of thin trivalent chrome layers were determined by small angle neutron scattering (SANS) without breaking the thin chrome layers. Most of defect size of the trivalent chromium prepared in this test conditions is in the range of about 40nm. The number of nano-size defects less than about 40nm of the trivalent chromium layer increases with plating voltage at constant current density From this study, SANS is proved as one of useful techniques to evaluate nano-size defects of thin film layer.

• Nuclear Engineering and Technology
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• v.10 no.3
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• pp.145-151
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• 1978

Based on the Butler scattering kernel for D$_2$O, a computer code DEUKEB has been developed to compute the scattering laws, differential scattering cross sections and total scattering cross sections. Interference scattering between ally two atoms of a D$_2$O molecule is important in resolving the distribution of scattered neutrons in thermal energy region. Energy-transfer scattering cross sections are, therefore, studied in the various incident neutron energies. This study may be put in practice to utilize the kernel in determining the neutron spectrum in a reactor system. The study also shows that the scattering process in D$_2$O is somewhat different from that in $H_2O$.