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O
with electrochemical Li
intercalationMurase, Satoshi*; Yoshikawa, Yumi*; Fujiwara, Kosuke*; Fukada, Yukimasa*; Teranishi, Takashi*; Kano, Jun*; Fujii, Tatsuo*; Inada, Yasuhiro*; Katayama, Misaki*; Yoshii, Kenji; et al.
Journal of Physics and Chemistry of Solids, 162, p.110468_1 - 110468_6, 2022/03
Times Cited Count：0 Percentile：0(Chemistry, Multidisciplinary)We report a trial of the valence control for mixed valence iron triangular oxide YbFeO in order to develop an effective technique to control the frustration of charges in strongly correlated electron systems. The electro-chemical doping of Li into YbFeO was examined on the cell type sample similar to the Li-ion secondary battery cell. Systematic change of the lattice constant, Fe-Fe and Fe-Yb distance were observed with Li doping. Maximum value of the doping was over 300 mAh/g. An EXAFS experiment indicated that Li positioned between Yb octahedron layer (U-layer) and Fe-bipyramidal layer (W-layer). However, detailed change of iron valence state of YbFeO was not clearly observed because of the superimpose of the signal from iron metal nano particles in XANES observation. The results indicate that the electrochemical method might be one of the potential technique to control the frustration of charges in YbFeO.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count：43 Percentile：96.93(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 
C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
Nakano, Masanao; Fujii, Tomoko; Nagaoka, Mika; Koike, Yuko; Yamada, Ryohei; Kubota, Tomohiro; Yoshii, Hideki*; Otani, Kazunori*; Hiyama, Yoshinori*; Kikuchi, Masaaki*; et al.
JAEA-Review 2020-070, 120 Pages, 2021/02
JAEA-Review-2020-070.pdf:2.47MB
Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2019. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.
Asahi, Yuichi; Fujii, Keisuke*; Heim, D. M.*; Maeyama, Shinya*; Garbet, X.*; Grandgirard, V.*; Sarazin, Y.*; Dif-Pradalier, G.*; Idomura, Yasuhiro; Yagi, Masatoshi*
Physics of Plasmas, 28(1), p.012304_1 - 012304_21, 2021/01
Times Cited Count：4 Percentile：43.17(Physics, Fluids & Plasmas)This article demonstrates a data compression technique for the time series of five dimensional distribution function data based on Principal Component Analysis (PCA). Phase space bases and corresponding coefficients are constructed by PCA in order to reduce the data size and the dimensionality. It is shown that about 83% of the variance of the original five dimensional distribution can be expressed with 64 components. This leads to the compression of the degrees of freedom from 
to 
. One of the important findings - resulting from the detailed analysis of the contribution of each principal component to the energy flux - deals with avalanche events, which are found to be mostly driven by coherent structures in the phase space, indicating the key role of resonant particles.
Nakano, Masanao; Fujii, Tomoko; Nagaoka, Mika; Inoue, Kazumi; Koike, Yuko; Yamada, Ryohei; Yoshii, Hideki*; Otani, Kazunori*; Hiyama, Yoshinori*; Kikuchi, Masaaki*; et al.
JAEA-Review 2019-045, 120 Pages, 2020/03
JAEA-Review-2019-045.pdf:2.54MB
Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2018. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.
nanocrystalsYoneda, Yasuhiro; Kunisada, Ryoichi*; Chikada, Tsukasa*; Ueno, Shintaro*; Fujii, Ichiro*; Nagata, Hajime*; Ohara, Koji*; Wada, Satoshi*
Japanese Journal of Applied Physics, 58(SL), p.SLLA03_1 - SLLA03_7, 2019/11
Times Cited Count：4 Percentile：21.91(Physics, Applied)Kasahara, Shigeki; Chimi, Yasuhiro; Hata, Kuniki; Fukuya, Koji*; Fujii, Katsuhiko*
Proceedings of 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors (Internet), p.1345 - 1355, 2019/08
This paper describes empirical equation development of crack growth rates (CGR) in consideration of IASCC of neutron irradiated stainless steel to contribute to structural integrity assessment of BWR reactor internals. Empirical equations of CGR (da/dt) were developed based on a formula of da/dt = M
K
, assuming that "M" and "n" tend to be saturated with increasing neutron fluence. To obtain the empirical equations for normal water chemistry (NWC) and hydrogen water chemistry (HWC) of BWR, a data fitting with least square method was applied to the datasets consisting of F, K and CGR from post irradiation examinations of neutron irradiated stainless steel under simulated NWC and HWC conditions from open literature. As a result, calculated results by the equation for NWC showed good agreement with measured CGR data, meanwhile those for HWC did not. The above difference was seemed to be attributed that CGR data obtained under HWC conditions were scattered extensively.
Fukuya, Koji*; Fujii, Katsuhiko*; Chimi, Yasuhiro; Hata, Kuniki
Proceedings of 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors (Internet), p.523 - 531, 2019/08
For structural integrity assessment on reactor internals of light water reactors, empirical equations of tensile properties as a function of neutron dose, and trend curves of stress-strain relations of neutron-irradiated austenitic stainless steels was proposed by fitting to recently developed database. The data in the database were obtained from reports of national projects in Japan and open literature, which was summarized in the form of data sheets. The empirical equations for tensile properties were formulated by using a saturation-type formulae. The equations were for CW 316 and SA 304/316 stainless steels in the temperature range of 280-350C and the dose range up to 80 dpa. Stress-strain relation curves were reproduced based on the Swift model. Obtained calculated results by the empirical equations and stress-strain relations were reasonably well fitted to experimental data. The effects of composition and cold-working, etc. on tensile properties were discussed.
Kasahara, Shigeki; Fukuya, Koji*; Fujimoto, Koji*; Fujii, Katsuhiko*; Chimi, Yasuhiro
JAEA-Review 2018-013, 171 Pages, 2019/01
JAEA-Review-2018-013.pdf:6.89MB
For structural integrity assessment of reactor internals of light water reactors, it is important to evaluate and predict the property changes of structural materials, based on existing data obtained from austenitic stainless steel irradiated with neutrons. Compilation of the data into tables is valuable for discussing the representative or the most probable values of the properties applied to the assessment. When the data compilation, the data must be distinguished clearly in consideration of different service conditions of core internals of pressurized water reactors (PWR) and boiling water reactors. Main objective of this work is to provide material property tables of irradiated austenitic stainless steel which will be applicable for assessment of structural integrity of core internals of PWRs. To compile the table, published literature reporting irradiated stainless steel data were surveyed and screened by considering the service conditions of PWRs. In addition to the data, various parameters for the data evaluation, e.g. chemical compositions and pre-treatments of the materials, irradiation and examination conditions, were extracted from the literature, and listed into tables.
Kasahara, Shigeki; Fukuya, Koji*; Koshiishi, Masato*; Fujii, Katsuhiko*; Chimi, Yasuhiro
JAEA-Review 2018-012, 180 Pages, 2018/11
JAEA-Review-2018-012.pdf:10.71MB
For structural integrity assessment of reactor internals of light water reactors, it is important to evaluate and predict the property changes of structural materials, based on existing data obtained from austenitic stainless steel irradiated with neutrons. Compilation of the data into tables is valuable for discussing the representative or the most probable values of the properties applied to the assessment. In the process of the data compilation, the data must be distinguished clearly in consideration of different service conditions of core internals of boiling water reactors (BWR) and pressurized water reactors. Main objective of this work is to provide material property tables of irradiated austenitic stainless steel which will be applicable for assessment of structural integrity of core internals of BWRs. To compile the table, published literature reporting irradiated stainless steel data were surveyed and screened by considering the service conditions of BWRs. In addition to the data, various parameters for the data evaluation, e.g. chemical compositions and pre-treatments of the materials, irradiation and examination conditions, were extracted from the literature, and listed into the tables.
O
Tsukada, Shinya*; Fujii, Yasuhiro*; Yoneda, Yasuhiro; Moriwake, Hiroki*; Konishi, Ayako*; Akishige, Yukikuni*
Physical Review B, 97(2), p.024116_1 - 024116_7, 2018/02
Times Cited Count：19 Percentile：65.6(Materials Science, Multidisciplinary)Uniaxial ferroelectric BaTiO with a Curie temperature 
of 743 K was investigated to clarify its paraelectric-ferroelectric phase transition behavior. The mechanism is discussed on the basis of the structure from short to long ranges determined by synchrotron X-ray diffraction and the lattice dynamics probed by Raman spectroscopy. Using a combination of experimental results and first-principles calculations, we explain the phase transition. Ti vibration of TiO
octahedral units is frozen in the ferroelectric phase and the space group changes from nonpolar 
to polar 
.
Nakamura, Shoji; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu; Tsubata, Yasuhiro; Matsumura, Tatsuro; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*
JAEA-Conf 2017-001, p.15 - 22, 2018/01
Neutron nuclear data of long lived fission products (LLFPs) have been required as basic data for the technology of reduce environmental impact involved in high level radioactive wastes (HLW). The innovative large project called by "Impusing Paradigm Change through Disruptive Technologies Program: ImPACT" have been started from October, 2014. In the ImPACT project, some research groups of JAEA engaged in the Project No.2 (Nuclear Reaction Data Measurements), and have started measurements of neutron capture cross-section at J-PARC/MLF/ANNRI. In our research, we selected cesium-135 (
Cs) nuclide (half life: 2.310
yr.) among LLFPs in the HLW, and decided to measure the neutron capture cross-sections of Cs. When measurement, the Cs sample might contained cecium-137 (
Cs) as impurities because it's impossible to chemically separate each other. To measure the cross-sections of Cs, there should be also needed to know the cross-sections of Cs. In this work, sample maintenance also has been examined especially for selen-79 (
Se) nuclide among LLFPs having difficulty in sample preparations. In this oral session, the outline of our research project will be presented together with a research motivation, situations of past reported data, total schedules, progress, future plans, and some of high light data for neutron capture cross-section measurements.
VAl probed by soft X-ray spectroscopiesNagai, Kodai*; Fujiwara, Hidenori*; Aratani, Hidekazu*; Fujioka, Shuhei*; Yomosa, Hiroshi*; Nakatani, Yasuhiro*; Kiss, Takayuki*; Sekiyama, Akira*; Kuroda, Fumiaki*; Fujii, Hitoshi*; et al.
Physical Review B, 97(3), p.035143_1 - 035143_8, 2018/01
Times Cited Count：21 Percentile：70.17(Materials Science, Multidisciplinary)We have studied the electronic structure of ferrimagnetic MnVAl single crystals by means of soft X-ray absorption spectroscopy (XAS), X-ray absorption magnetic circular dichroism (XMCD), and resonant soft X-ray inelastic scattering (RIXS). We have successfully observed the XMCD signals for all the constituent elements. The Mn L
XAS and XMCD spectra are reproduced by spectral simulations based on density-functional theory, indicating the itinerant character of the Mn 3
states. On the other hand, the V 3 electrons are rather localized since the ionic model can qualitatively explain the V L XAS and XMCD spectra. This picture is consistent with local 
excitations revealed by the V L
RIXS.
MnO (
2/
) for a lithium-battery cathode in several charge-discharge potential rangesNakao, Yasuhiro*; Ozawa, Kiyoshi*; Fujii, Hiroki*; Mochiku, Takashi*; Iwai, Hideo*; Tsuchiya, Yoshinori*; Igawa, Naoki
Transactions of the Materials Research Society of Japan, 38(2), p.229 - 233, 2013/12
LiMnO powder with a monoclinic cell related to the space group of 2/ was synthesized by a simplified coprecipitation method. Its electrode properties as a lithium-battery cathode were investigated in the charge-discharge potential ranges of 2.0 - 4.6, 2.0 - 4.8, and 2.0 - 5.0 V. In all the potential ranges, the electrochemical capacities gradually increased during cycling, and the increased capacities significantly depended on the potential ranges. Compared to the discharge capacities for the potential ranges of 2.0 - 4.6 and 2.0 - 5.0 V, the former merely increased from 12.5 to 22.5 mAhg
between the 1st and 99th cycles, whereas the latter increased from 20.0 to 110.2 mAhg during the same cycling. The structural variation in LiMnO is induced by the cycling, the rhombohedral phase is detected during cycling in the potential range of 2.0 - 5.0 V.
Mn
Co
O (2/) as a lithium-battery cathodeOzawa, Kiyoshi*; Nakao, Yasuhiro*; Mochiku, Takashi*; Cheng, Z.*; Wang, L.*; Iwai, Hideo*; Tsuchiya, Yoshinori*; Fujii, Hiroki*; Igawa, Naoki
Journal of the Electrochemical Society, 159(3), p.A300 - A304, 2012/01
Times Cited Count：14 Percentile：46.73(Electrochemistry)A manganese-based solid solution with the composition of LiMnCoO was synthesized by a simplified coprecipitation method, and its electrochemical characteristics as a lithium-battery cathode were investigated. Rietveld refinement based on neutron diffraction data revealed that the material is assigned to an LiMnO-type structure model with a space group symmetry of 2/. In cycling of the cell in the potential range from 2.0 to 4.8 V at current densities of 30 mAhg, the discharge capacity characteristically increases from 46.3 to 196.5 mAhg as the cycle increases from 1 to 11, and a discharge capacity above 175.5 mAhg is obtained between the 23rd and 58th cycles. The cyclic voltammogram and X-ray photoelectron spectroscopy measurements showed that the manganese redox reaction is progressively activated during the first ten-odd cycles.
O moderated 
Cf source at JAEA and KAERIKowatari, Munehiko; Fujii, Katsutoshi; Tsutsumi, Masahiro; Kim, B.-H.*; Lee, K.-C.*; Yoshizawa, Michio; Yamaguchi, Yasuhiro
Journal of Nuclear Science and Technology, 45(Suppl.5), p.217 - 220, 2008/06
Times Cited Count：1 Percentile：10.05(Nuclear Science & Technology)no abstracts in English
O-moderated Cf sourceKowatari, Munehiko; Fujii, Katsutoshi; Takahashi, Masa; Yoshizawa, Michio; Shimizu, Shigeru; Kawasaki, Katsuya; Yamaguchi, Yasuhiro
Radiation Protection Dosimetry, 126(1-4), p.138 - 144, 2007/08
Times Cited Count：5 Percentile：37.19(Environmental Sciences)The facility of the Radiation Standards (FRS) of the Japan Atomic Energy Agency was equipped with the reference neutron field by using DO moderated Cf neutron source (DO-Cf), with a 30cm diameter DO sphere. In order to determine the characteristics of the reference field within the ranges of calibration distance (75 to 200 cm from the center of the source to the calibration point) in detail, the authors performed the evaluation of the neutron spectra and neutron fluence rate at various distances from the DO moderated source assembly by computations using MCNP-4C and by experimental studies using Bonner Multi-sphere neutron Spectrometer (BMS). Due to the volume neutron source, it is difficult to measure the contribution of the scattered neutron component with the desirable accuracy by shadow-cone method. In this study, the net counting rate of each counter of BMS was corrected by estimating the ratio of the counting rate of each counter in condition of the experimental and the ideal arrangement by the Monte Carlo calculation. The spectra of the direct component were unfolded by using the corrected counting rate with SAND II code. The averaged dose conversion coefficients (h
(10) and h
(10)) and neutron dose rates (H(10) and H(10)) at various distance were estimated based on the measured spectra. The effectiveness of the correction was discussed by comparing the measured and calculated values. Additionally, the suitable distance for the calibration of personal dosimeter at FRS reference field was evaluated by the results.
Takeishi, Minoru; Miyagawa, Naoto; Uezu, Yasuhiro; Nakano, Masanao; Koarashi, Jun; Mizutani, Tomoko; Kono, Takahiko; Hiyama, Yoshinori*; Fujii, Yoshiyuki*; Kikuchi, Masaaki*; et al.
JAEA-Review 2006-024, 133 Pages, 2006/09
JAEA-Review-2006-024.pdf:6.69MB
Based on the regulations (the safety regulation of Tokai reprocessing plant, the safety regulation of nuclear fuel usage facilities, radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear reguratory acts, and the local agreement concerning with security and environment conservation around nuclear facilities, the water pollution control law, and byelaw of Ibaraki prefecture), this report describes the effluent control results of low level liquid waste discharged from the JAEA's Nuclear Fuel Cycle Engineering Laboratories in the fiscal year 2005, from 1st April 2005 to 31th March 2006. In this period, the concentrations and the quantities of the discharged radioactive materials from the reprocessing plant, the plutonium fuel fabrication facilities, and the other facilities were much lower than the authorized limits of the above regulations.
Takeishi, Minoru; Naoto, Miyagawa,; Hitoshi, Watanabe,; Uezu, Yasuhiro; Mizutani, Tomoko; Hiyama, Yoshinori*; Fujii, Jun*
JNC TN8440 2005-008, 136 Pages, 2005/08
JNC-TN8440-2005-008.pdf:4.14MB
This report was written about the effluent control in JNC Tokai Works from 1st April 2004 to 31th March 2005. In this period, the quantities and concentrations of retroactivities in liquid waste from Tokai Works were under the discharge limits of "Safety Regulations for the Tokai Reprocessing Plant " and regulations of government.
Shinohara, Kunihiko; Takeishi, Minoru; Hitoshi, Watanabe,; Uezu, Yasuhiro; Mizutani, Tomoko; Hiyama, Yoshinori*; Fujii, Jun*
JNC TN8440 2004-015, 138 Pages, 2004/12
JNC-TN8440-2004-015.pdf:7.78MB
This report was written about the effluent control in JNC Tokai Works from 1st April 2003 to 31th March 2004. In this period, the quantities and concentrations of retroactivities in liquid waste from Tokai Works were under the discharge limits of "Safety Regulations for the Tokai Reprocessing Plant" and regulations of government.
