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Journal Articles

Muon spin relaxation in mixed perovskite (LaAlO)(SrAl $_{0.5}$ Ta $_{0.5}$ O) $_{1-x}$ with

Ito, Takashi; Higemoto, Wataru; Koda, Akihiro*; Nakamura, Jumpei*; Shimomura, Koichiro*

Interactions (Internet), 245(1), p.25_1 - 25_7, 2024/12

https://doi.org/10.1007/s10751-024-01866-5

Journal Articles

Development of correction method for sample density effect on PGA

Maeda, Makoto; Segawa, Mariko; Toh, Yosuke; Endo, Shunsuke; Nakamura, Shoji; Kimura, Atsushi

Journal of Radioanalytical and Nuclear Chemistry, 332(8), p.2995 - 2999, 2023/08

https://doi.org/10.1007/s10967-023-08961-x

Times Cited Count：0 Percentile：0.01(Chemistry, Analytical)

JAEA Reports

Investigation of the core neutronics analysis conditions for evaluation of burn-up nuclear characteristics of the next-generation fast reactors

Takino, Kazuo; Oki, Shigeo

JAEA-Data/Code 2023-003, 26 Pages, 2023/05

JAEA-Data-Code-2023-003.pdf:1.66MB

Since next-generation fast reactors aim to achieve a higher core discharge burn-up than conventional reactors do, core neutronics design methods must be refined. Therefore, a suitable analysis condition is required for the analysis of burn-up nuclear characteristics to accomplish sufficient estimation accuracy while maintaining a low computational cost. We investigated the effect of the analysis conditions on the accuracy of estimation of the burn-up nuclear characteristics of next-generation fast reactors in terms of neutron energy groups, neutron transport theory, and spatial mesh. This study treated the following burn-up nuclear characteristics: criticality, burn-up reactivity, control rod worth, breeding ratio, assembly-wise power distribution, maximum linear heat rate, sodium void reactivity, and Doppler coefficient for the equilibrium operation cycle. As a result, it was found that the following conditions were the most suitable: 18-energy-group structure, 6 spatial meshes per assembly with diffusion approximation. Additionally, these conditions should apply to correction factors for energy group structure, spatial mesh and transport effects.

Journal Articles

Correction method of measurement volume effects on time-averaged statistics for laser Doppler velocimetry

Wada, Yuki; Furuichi, Noriyuki*; Tsuji, Yoshiyuki*

European Journal of Mechanics B, Fluids, 91, p.233 - 243, 2022/01

https://doi.org/10.1016/j.euromechflu.2021.10.007

Times Cited Count：1 Percentile：21.05(Mechanics)

Journal Articles

True coincidence summing correction for cylindrical volume samples in -ray spectrometry

Yamada, Takashi*; Asai, Masato; Yonezawa, Chushiro*; Kakita, Kazutoshi*; Hirai, Shoji*

Radioisotopes, 69(9), p.287 - 297, 2020/09

https://doi.org/10.3769/radioisotopes.69.287

We have confirmed that the commercially available Japanese "standard" gamma-ray analysis programs do not consider the effect of sample volume in calculating true coincidence summing (TCS) corrections, which results in underestimation of $^{134}$ Cs radioactivity in cylindrical volume samples. In this work, we have developed and examined a practical TCS correction method for general Ge detectors which consider the effect of sample volume properly, and have confirmed that this method can reduce the $^{134}$ Cs radioactivity underestimation to less than 1%.

Journal Articles

Preliminary test of the EA-AGE3 system for $^{14}$ C measurement of CaCO $_{3}$ samples and coral-based estimation of marine reservoir correction in the Ogasawara Islands, Northwestern Subtropical Pacific

Kokubu, Yoko; Mitsuguchi, Takehiro*; Watanabe, Takahiro; Yamada, Tsutomu*; Asami, Ryuji*; Iryu, Yasufumi*

Radiocarbon, 61(5), p.1593 - 1601, 2019/10

https://doi.org/10.1017/RDC.2019.69

Times Cited Count：1 Percentile：5.84(Geochemistry & Geophysics)

We performed $^{14}$ C measurements of two fossil and one modern corals using a combined system of an elemental analyzer and an automated graphitization equipment AGE3 (EA-AGE3 system) and JAEA-AMS-TONO. The $^{14}$ C concentrations (pMC values) of mid-Holocene Okinawa corals obtained by our EA-AGE3 system appear to be slightly higher than those obtained by the conventional graphitization method using phosphoric acid. The pMC increase in our EA-AGE3 system may result in significant underestimation of $^{14}$ C age especially for older samples (e.g., 10,000 BP); however, the pMC increase is negligible in $^{14}$ C measurements of modern or recent samples. We applied the EA-AGE3 method to the pre- and post-bomb annual-band samples from the modern Ogasawara coral for $^{14}$ C measurements. On the basis of the pre-bomb coral $^{14}$ C data, we estimated marine reservoir correction (R) around Ogasawara Islands and its stability between 1900 and 1950 AD.

Journal Articles

Plasticity correction on the stress intensity factor evaluation for underclad cracks under pressurized thermal shock events

Lu, K.; Katsuyama, Jinya; Li, Y.

Proceedings of 2016 ASME Pressure Vessels and Piping Conference (PVP 2016) (Internet), 8 Pages, 2016/07

https://doi.org/10.1115/PVP2016-63486

Journal Articles

Role of van der Waals corrections in first principles simulations of alkali metal ions in aqueous solutions

Ikeda, Takashi; Boero, M.*

Journal of Chemical Physics, 143(19), p.194510_1 - 194510_7, 2015/11

https://doi.org/10.1063/1.4935932

Times Cited Count：29 Percentile：74.71(Chemistry, Physical)

By resorting to a novel implementation of the first-principles-based van der Waals correction based on maximally localized Wannier functions, we inspect its performance and assess its reliability for aqueous solutions of alkali metal ions. We find that van der Waals interactions, when added to the widely used revPBE gradient corrected functional, influence substantially both structural and dynamical properties of water molecules, with particular emphasis on the hydration shell of the alkali cations. These effects are more evident for strong structure-making and -breaking cationic species. Moreover, self-diffusion coefficients and reorientation correlation times of solvating water molecules change systematically, showing a trend in better agreement with experiments with respect to simulations neglecting the long-range dispersion contributions.

Journal Articles

A Crafty utilization of intermediate-angle neutron scattering and contrast variation by water-exchange to study the microstructure of microbial cellulose

Zhao, Y.; Koizumi, Satoshi*; Kondo, Tetsuo*

JPS Conference Proceedings (Internet), 8, p.033002_1 - 033002_6, 2015/09

https://doi.org/10.7566/JPSCP.8.033002

JAEA Reports

Study of beam fluctuation of high speed variably-polarizing undulator APPLE-2 in 2001 Dec.-2002 Nov.

Nakatani, Takeshi; Agui, Akane; Yoshigoe, Akitaka; Tanaka, Hitoshi*; Takao, Masaru*; Takeuchi, Masao*; Matsushita, Tomohiro*; Aoyagi, Hideki*

JAERI-Tech 2005-027, 29 Pages, 2005/05

JAERI-Tech-2005-027.pdf:5.14MB

We measured the orbit fluctuation caused by APPLE-2 type undulator (ID23) installed in the SPring-8 storage ring by using the developed real time measurement system of electron and photon beam position monitors. We quantitatively found two characteristic fluctuations correlating with the ID23 motion by wavelet transform which is a kind of frequency analysis. One originates from the variation of error field during the ID drive. The other originates from the stray magnetic field leaked from the servomotors for the phase drive. Using these results, we tried to get rid of the effect of error fields on the beam orbit by the precise feed-forward correction table and the stray field shield. Consequently we succeeded in suppressing the orbit fluctuation down to sub-micron during the gap drive, which is observed by photon beam position monitors installed in downstream 20m from each light source point.

JAEA Reports