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Journal Articles

Time-resolved 3D visualization of liquid jet breakup and impingement behavior in a shallow liquid pool

Kimura, Fumihito*; Yamamura, Sota*; Fujiwara, Kota*; Yoshida, Hiroyuki; Saito, Shimpei*; Kaneko, Akiko*; Abe, Yutaka*

Nuclear Engineering and Design, 389, p.111660_1 - 111660_11, 2022/04

Journal Articles

Valence control of charge and orbital frustrated system YbFe$$_{2}$$O$$_{4}$$ with electrochemical Li$$^{+}$$ intercalation

Murase, 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

We report a trial of the valence control for mixed valence iron triangular oxide YbFe$$_{2}$$O$$_{4}$$ 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 YbFe$$_{2}$$O$$_{4}$$ 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 YbFe$$_{2}$$O$$_{4}$$ 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 YbFe$$_{2}$$O$$_{4}$$.

Journal Articles

Development of dispersed phase tracking method for time-series 3-dimensional interface shape data

Horiguchi, Naoki; Yoshida, Hiroyuki; Yamamura, Sota*; Fujiwara, Kota*; Kaneko, Akiko*; Abe, Yutaka*

Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 14 Pages, 2022/03

Journal Articles

Radiocesium transfer into freshwater planktonic ${it Chlamydomonas}$ spp. microalgae in a pond near the Fukushima Dai-ichi Nuclear Power Plant

Sasaki, Yoshito; Funaki, Hironori; Fujiwara, Kenso

Limnology, 23(1), p.1 - 7, 2022/01

We investigated the transfer behavior of radiocesium in living cells and remains of a bloom of microalgae (${it Chlamydomonas}$ sp.) in a pond located about 5 km from the Fukushima Dai-ichi Nuclear Power Plant. As a positive correlation was detected between the cell number of microalgae and the radiocesium concentration (Bq/L) in the $$>$$ 0.45-$$mu$$m fraction, microalgae were the controlling factor for the radiocesium concentration of the $$>$$ 0.45-$$mu$$m fraction. The transfer factor of water-to-algae [($$^{137}$$Cs concentration Bq/kg $$>$$ 0.45-$$mu$$m fraction) $$times$$ ($$^{137}$$Cs concentration Bq/L water)$$^{-1}$$] was 1.6 $$times$$ 10$$^{3}$$. The radiocesium concentration of microalgae remains was the same as that in intact cells.

Journal Articles

Space weather benchmarks on Japanese society

Ishii, Mamoru*; Shiota, Daiko*; Tao, Chihiro*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Ishii, Takako*; Ichimoto, Kiyoshi*; Kataoka, Ryuho*; Koga, Kiyokazu*; Kubo, Yuki*; et al.

Earth, Planets and Space (Internet), 73(1), p.108_1 - 108_20, 2021/12

 Times Cited Count:1 Percentile:72.01(Geosciences, Multidisciplinary)

We surveyed the relationship between the scale of space weather events and their occurrence rate in Japan and we discussed the social impact of these phenomena during the Project for Solar-Terrestrial Environment Prediction (PSTEP). The information was compiled for domestic users of space weather forecasts for appropriate preparedness against space weather disasters. This paper gives a comprehensive summary of the survey, focusing on the fields of electricity, satellite operations, communication and broadcasting, satellite positioning usage, aviation, human space activity, and daily life on the Earth's surface, using the cutting-edge knowledge of space weather. Quantitative estimations of the economic impact of space weather events on electricity and aviation are also given.

Journal Articles

Sm valence determination of Sm-based intermetallics using $$^{149}$$Sm M$"{o}$ssbauer and Sm L$$_{rm III}$$-edge X-ray absorption spectroscopies

Tsutsui, Satoshi; Higashinaka, Ryuji*; Nakamura, Raito*; Fujiwara, Kosuke*; Nakamura, Jin*; Kobayashi, Yoshio*; Ito, Takashi; Yoda, Yoshitaka*; Kato, Kazuo*; Nitta, Kiyofumi*; et al.

Hyperfine Interactions, 242(1), p.32_1 - 32_10, 2021/12

Journal Articles

Emergence of spin-orbit coupled ferromagnetic surface state derived from Zak phase in a nonmagnetic insulator FeSi

Otsuka, Yusuke*; Kanazawa, Naoya*; Hirayama, Motoaki*; Matsui, Akira*; Nomoto, Takuya*; Arita, Ryotaro*; Nakajima, Taro*; Hanashima, Takayasu*; Ukleev, V.*; Aoki, Hiroyuki; et al.

Science Advances (Internet), 7(47), p.eabj0498_1 - eabj0498_9, 2021/11

Journal Articles

Microscopic dynamics of lithium diffusion in single crystal of the solid-state electrolyte La$$_{2/3-x}$$Li$$_{3x}$$TiO$$_{3}$$ (x = 0.13) studied by quasielastic neutron scattering

Matsuura, Masato*; Fujiwara, Yasuyuki*; Moriwake, Hiroki*; Ohara, Koji*; Kawakita, Yukinobu

Physical Review B, 104(9), p.094305_1 - 094305_7, 2021/09

 Times Cited Count:0

Journal Articles

Rapid analysis of $$^{90}$$Sr in cattle bone and tooth samples by inductively coupled plasma mass spectrometry

Koarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Yanagisawa, Kayo*; Terashima, Motoki; Fujiwara, Kenso; Kino, Yasushi*; Oka, Toshitaka; Takahashi, Atsushi*; Suzuki, Toshihiko*; et al.

Journal of Analytical Atomic Spectrometry, 36(8), p.1678 - 1682, 2021/08

 Times Cited Count:0 Percentile:0.02(Chemistry, Analytical)

Rapid analysis of $$^{90}$$Sr in bone and tooth samples of cattle were achieved by an inductively coupled plasma mass spectrometry (ICP-MS) coupled with mass shift and solid phase extraction techniques. Limit of detection (LOD) in the ICP-MS measurement of 0.1 g samples was lower than that of the radioactivity measurement. Analytical time of the ICP-MS method was reduced from 20 days to 11 hours, compared with the radiometric method. Therefore, the ICP-MS method can be rapid and useful procedure of $$^{90}$$Sr in small bone and tooth samples derived from terrestrial animals.

Journal Articles

Online solid-phase extraction-inductively coupled plasma-quadrupole mass spectrometry with oxygen dynamic reaction for quantification of technetium-99

Matsueda, Makoto; Yanagisawa, Kayo*; Koarai, Kazuma; Terashima, Motoki; Fujiwara, Kenso; Abe, Hironobu; Kitamura, Akihiro; Takagai, Yoshitaka*

ACS Omega (Internet), 6(29), p.19281 - 19290, 2021/07

 Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)

Online solid-phase extraction-inductively coupled plasma-quadrupole mass spectrometry with oxygen dynamic reaction cell (online SPE-ICP-MS-DRC) was shown to be a thorough automatic analytical system, circumventing the need for human handling. At three stepwise separations (SPE-DRC-Q mass filters), we showed that interference materials allowed the coexistence of abundance ratios of 1.5$$times$$10$$^{-13}$$ for $$^{99}$$Tc/Mo. Using this optimized system, a detection limit of $$^{99}$$Tc was 9.3 pg/L (5.9 mBq/L) for a 50 mL injection and sequential measurements were undertaken at a cycle of 24 min/sample.

JAEA Reports

Development of solid-phase extraction technique for ICP-MS analysis of iodine-129 in environmental samples; Comparative study of anion-exchange and silver ion-supported resins on isolation of Iodine-129 from interference elements

Aoki, Jo; Matsueda, Makoto; Koarai, Kazuma; Terashima, Motoki; Fujiwara, Kenso; Abe, Hironobu

JAEA-Research 2021-002, 20 Pages, 2021/05

JAEA-Research-2021-002.pdf:2.75MB

In order to analyze extremely low concentrations of $$^{129}$$I in environmental samples by ICP-MS with high sensitivity and rapidity, it is necessary to remove interfering elements (Na, Mg, K, Ca, Mo, Cd and In) using a pretreatment method with Solid-phase Extraction Resin. Anion Exchange Resins with amino groups have been widely used as Solid-phase Extraction Resins, while Ag+ Supported Resins have also been widely used in recent years. It is necessary to optimize the pretreatment technique based on characteristics of the resins. In this study, we compared in terms of separation of I from matrix elements (Na, Mg, K, Ca, Mo, Cd and In) for DOWEX1-X8, AG 1-X8 and CL Resin, and investigated their suitability for ICP-MS analysis of $$^{129}$$I in environmental samples. The results of adsorption and elution experiments showed that all resins examined uptake and elute I quantitatively. CL Resin showed the highest removal performance of interfering elements, with 3.1% of Mo remaining, but other interfering elements were removed below the detection limit of ICP-MS. However, the Mo remained after the CL Resin treatment could interfere the ICP-MS measurement of $$^{129}$$I, based on the consideration of ratio of $$^{129}$$I and Mo. The eluate from CL Resin was treated with a Cation exchange resin (DOWEX 50WX8). As a result, Mo in the eluate was removed by up to 98% and the interference from Mo was reduced to measurable level. Therefore, the pretreatment method using CL Resin in combination with DOWEX 50WX8 is effective for ICP-MS analysis of $$^{129}$$I at extremely low concentrations (background level).

Journal Articles

High temperature gas-cooled reactors

Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.

High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02

As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950$$^{circ}$$C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.

Journal Articles

Applicability of Sr resin for ICP-MS measurement of $$^{90}$$Sr in hard tissue samples

Koarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Yanagisawa, Kayo*; Fujiwara, Kenso; Terashima, Motoki; Kitamura, Akihiro; Abe, Hironobu

KEK Proceedings 2020-4, p.180 - 185, 2020/11

Strontium-90 and $$^{90}$$Y, its daughter nuclide, adverse effects on the bone marrow. Monitoring of $$^{90}$$Sr in the bones have been required after the Fukushima-Daiichi Nuclear Power Plant accident. However, conventional radioactivity measurement method for $$^{90}$$Sr requires a complicated separation of $$^{90}$$Y and a time-consuming measurement. ICP-MS system has been applied to $$^{90}$$Sr concentration survey of water, soil, and edible part of fish. We applied the ICP-MS system for the bones for the first time. In this study, reference bone (JSAC 0785 fish bone) was used as measurement samples. Sample preparation of the bone was performed using a microwave digestion instrument. After sample preparation, $$^{90}$$Sr was determined using ICP-MS system with cascade separation steps based on on-line column separation and oxygen reaction. Strontium-90 in the bones was successfully separated from Ca, Ba, Y, Zr, Fe, Se, and Ge, which interfered in ICP-MS measurement, in the separation steps.

Journal Articles

Radiocesium distribution in the sediments of the Odaka River estuary, Fukushima, Japan

Hagiwara, Hiroki; Nakanishi, Takahiro; Konishi, Hiromi*; Tsuruta, Tadahiko; Misono, Toshiharu; Fujiwara, Kenso; Kitamura, Akihiro

Journal of Environmental Radioactivity, 220-221, p.106294_1 - 106294_9, 2020/09

 Times Cited Count:0 Percentile:0(Environmental Sciences)

Journal Articles

Rapid tritium analysis for marine products in the coastal area of Fukushima

Kuwata, Haruka*; Misono, Toshiharu; Fujiwara, Kenso; Takeishi, Minoru; Manabe, Sachi*; Kitamura, Akihiro

Radiation Environment and Medicine, 9(1), p.28 - 34, 2020/02

The analysis of tritium in aquatic biota is one of the most important research areas in Fukushima. The conventional method for measuring the concentration of tritium consists of complicated pretreatment procedures and requires skillful techniques as well as a significant amount of time. Consequently, there are only a few reports on tritium monitoring data in marine products from the coast of Fukushima. In this study, we measured the Tissue Free Water Tritium (TFWT) and Organically Bound Tritium (OBT) in flounders collected from the coast of Fukushima to examine the impacts of the nuclear accident on aquatic biota. The study was done for a period of 4 years; from 2015 to 2018. The conventional method of analysis was firstly used, after which the method was modified by improving the freeze-drying and combustion water recovery processes. Results from both methods show that the most of the concentrations of the TFWT and OBT in the flounder were below the detection or quantitative limit. The effect of the nuclear accident on humans, through internal exposure, was also examined and found to be negligible. Although some uncertainties exist due to the short cut of the processes, the modified version could be considered an effective and practical approximate method.

Journal Articles

Mineral composition characteristics of radiocesium sorbed and transported sediments within the Tomioka river basin in Fukushima Prefecture

Hagiwara, Hiroki; Konishi, Hiromi*; Nakanishi, Takahiro; Fujiwara, Kenso; Iijima, Kazuki; Kitamura, Akihiro

Journal of Environmental Radioactivity, 211, p.106042_1 - 106042_10, 2020/01

 Times Cited Count:2 Percentile:39.03(Environmental Sciences)

Journal Articles

Temporal decrease in air dose rate in the sub-urban area affected by the Fukushima Dai-ichi Nuclear Power Plant accident during four years after decontamination works

Nakama, Shigeo; Yoshimura, Kazuya; Fujiwara, Kenso; Ishikawa, Hiroyasu; Iijima, Kazuki

Journal of Environmental Radioactivity, 208-209, p.106013_1 - 106013_8, 2019/11

 Times Cited Count:5 Percentile:37.91(Environmental Sciences)

Trends of air dose rate decrease after decontamination works and factors which affect them constitute essential information for radiation protection, such as prediction of external exposure to the public and implementation of measures to reduce such exposure. This study investigated the decrease of air dose rate (ambient dose rate at 1 m above the ground) at 163 points across sub-urban areas in the evacuation zone around the Fukushima Dai-ichi Nuclear Power Plant over the period of four years following the decontamination works carried out in November 2012. The air dose rate on the asphalt pavement decreased faster than on soil surfaces. In addition, air dose rates near the forest decreased at a slower pace than in open fields. These results suggest that the air dose rate in urbanized areas can decrease faster than in other types of land, even after decontamination. Based on comparisons with decrease rates obtained in other studies, the air dose rate tends to decrease faster outside the evacuation zone than inside it. The decrease in air dose rate after decontamination was slower than before decontamination. The contribution of the weathering effect and human activity was estimated to be about 80% and 20% of the ecological decrease rate, respectively.

Journal Articles

Dynamic properties of human $$alpha$$-synuclein related to propensity to amyloid fibril formation

Fujiwara, Satoru*; Kono, Fumiaki*; Matsuo, Tatsuhito*; Sugimoto, Yasunobu*; Matsumoto, Tomoharu*; Narita, Tetsuhiro*; Shibata, Kaoru

Journal of Molecular Biology, 431(17), p.3229 - 3245, 2019/08

 Times Cited Count:3 Percentile:27.91(Biochemistry & Molecular Biology)

$$alpha$$-synuclein ($$alpha$$Syn) is an intrinsically disordered protein (IDP) with unknown function. $$alpha$$Syn is known to form amyloid fibrils, which are implicated with the pathogenesis of Parkinson's disease and other synucleinopathies. Elucidating the mechanism of fibril formation of $$alpha$$Syn is therefore important for understanding the mechanism of the pathogenesis of these diseases. Here, using the quasielastic neutron scattering (QENS) and small-angle X-ray scattering (SAXS) techniques, we investigated the dynamic and structural properties of $$alpha$$Syn. These results imply that fibril formation of $$alpha$$Syn requires not only the enhanced local motions but also the segmental motions such that the proper inter-molecular interactions are possible.

Journal Articles

Development of the ReaxFF methodology for electrolyte-water systems

Fedkin, M. V.*; Shin, Y. K.*; Dasgupta, N.*; Yeon, J.*; Zhang, W.*; van Duin, D.*; Van Duin, A. C. T.*; Mori, Kento*; Fujiwara, Atsushi*; Machida, Masahiko; et al.

Journal of Physical Chemistry A, 123(10), p.2125 - 2141, 2019/03

 Times Cited Count:15 Percentile:89.91(Chemistry, Physical)

no abstracts in English

Journal Articles

Optimization of mechanical properties in aluminum alloys $$via$$ hydrogen partitioning control

Toda, Hiroyuki*; Yamaguchi, Masatake; Matsuda, Kenji*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Su, H.*; Fujiwara, Hiro*; Ebihara, Kenichi; Itakura, Mitsuhiro; Tsuru, Tomohito; et al.

Tetsu To Hagane, 105(2), p.240 - 253, 2019/02

 Times Cited Count:0 Percentile:0(Metallurgy & Metallurgical Engineering)

no abstracts in English

316 (Records 1-20 displayed on this page)