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Journal Articles

A Design study on a metal fuel fast reactor core for high efficiency minor actinide transmutation by loading silicon carbide composite material

Ohgama, Kazuya; Hara, Toshiharu*; Ota, Hirokazu*; Naganuma, Masayuki; Oki, Shigeo; Iizuka, Masatoshi*

Journal of Nuclear Science and Technology, 59(6), p.735 - 747, 2022/06

Journal Articles

Improvement of neutron diffraction at compact accelerator-driven neutron source RANS using peak profile deconvolution and delayed neutron reduction for stress measurements

Iwamoto, Chihiro*; Takamura, Masato*; Ueno, Kota*; Kataoka, Minami*; Kurihara, Ryo*; Xu, P. G.; Otake, Yoshie*

ISIJ International, 62(5), p.1013 - 1022, 2022/05

Journal Articles

Hyperfine splitting and nuclear spin polarization in NdPd$$_5$$Al$$_2$$ and Nd$$_3$$Pd$$_{20}$$Ge$$_6$$

Metoki, Naoto; Shibata, Kaoru; Matsuura, Masato*; Kitazawa, Hideaki*; Suzuki, Hiroyuki*; Yamauchi, Hiroki; Hagihara, Masato; Frontzek, M. D.*; Matsuda, Masaaki*

Journal of the Physical Society of Japan, 91(5), p.054710_1 - 054710_6, 2022/05

Hyperfine splitting of Nd nuclei in NdPd$$_5$$Al$$_2$$ has been studied by means of high-resolution neutron spectroscopy. We observed inelastic peaks at $$hbaromega =pm3;{mu}$$eV coming from the hyperfine splitting in the magnetically ordered phase due to the hyperfine interactions between Nd nuclei ($$I$$=7/2) and the 4$$f$$ electrons with $$Gamma_6$$ ground state composed of mainly $$|pm9/2rangle$$. At very low temperatures, nuclear spin of Nd is polarized with increasing occupation probability of low energy levels and contributes to the enhancement of the antiferromagnetic Bragg intensities: the elastic non-spin-flip channel is dominant. As an application of this phenomenon, we determined the Nd moment and hyperfine splitting from the temperature dependence of an antiferromagnetic Bragg intensities for Nd$$_3$$Pd$$_{20}$$Ge$$_6$$.

Journal Articles

Magnetism of Al$$_{x}$$Fe$$_{2-x}$$GeO$$_{5}$$ with andalusite structure

Kakimoto, Kazuo*; Takada, Saki*; Ota, Hiroto*; Hayaguchi, Yuya*; Hagihara, Masato; Torii, Shuki*; Kamiyama, Takashi*; Mitamura, Hiroyuki*; Tokunaga, Masashi*; Hatakeyama, Atsushi*; et al.

Journal of the Physical Society of Japan, 91(5), p.054704_1 - 054704_7, 2022/05

Journal Articles

Sinusoidal magnetic structure of andalusite-type AlxFe$$_{2}$$-xGeO$$_{5}$$ with $$x$$ = 0.09 and 0.15

Kakimoto, Kazuo*; Ota, Hiroto*; Haraguchi, Yuya*; Hagihara, Masato; Torii, Shuki*; Kamiyama, Takashi*; Katori, Hiroko*

Journal of the Physical Society of Japan, 91(5), p.054707_1 - 054707_9, 2022/05

Journal Articles

Structural phase transition in cobalt oxyfluoride Co$$_{3}$$Sb$$_{4}$$O$$_{6}$$F$$_{6}$$ observed by high-resolution synchrotron and neutron diffraction

Shimono, Seiya*; Ishibashi, Hiroki*; Nagayoshi, Yusuke*; Ikeno, Hidekazu*; Kawaguchi, Shogo*; Hagihara, Masato; Torii, Shuki*; Kamiyama, Takashi*; Ichihashi, Katsuya*; Nishihara, Sadafumi*; et al.

Journal of Physics and Chemistry of Solids, 163, p.110568_1 - 110568_7, 2022/04

Journal Articles

A Storm-induced flood and associated nearshore dispersal of the river-derived suspended $$^{137}$$Cs

Uchiyama, Yusuke*; Tokunaga, Natsuki*; Azuma, Kohei*; Kamidaira, Yuki; Tsumune, Daisuke*; Iwasaki, Toshiki*; Yamada, Masatoshi*; Tateda, Yutaka*; Ishimaru, Takashi*; Ito, Yukari*; et al.

Science of the Total Environment, 816, p.151573_1 - 151573_13, 2022/04

no abstracts in English

Journal Articles

Contrasting magnetic structures in SrLaCuSbO$$_{6}$$ and SrLaCuNbO$$_{6}$$; Spin-$$frac{1}{2}$$ quasi-square-lattice $$J_{1}$$-$$J_{2}$$ Heisenberg antiferromagnets

Watanabe, Masari*; Kurita, Nubuyuki*; Tanaka, Hidekazu*; Ueno, Wataru*; Matsui, Kazuki*; Goto, Takayuki*; Hagihara, Masato

Physical Review B, 105(5), p.054414_1 - 054414_12, 2022/02

Journal Articles

Seismic classification of high temperature engineering test reactor

Ono, Masato; Shimizu, Atsushi; Ohashi, Hirofumi; Hamamoto, Shimpei; Inoi, Hiroyuki; Tokuhara, Kazumi*; Nomoto, Yasunobu*; Shimazaki, Yosuke; Iigaki, Kazuhiko; Shinozaki, Masayuki

Nuclear Engineering and Design, 386, p.111585_1 - 111585_9, 2022/01

In the late 1980s during the design stage, the seismic classification of the high temperature engineering test reactor (HTTR) was formulated. Owing to the lack of operation experiences of the HTTR to sufficiently understand the safety characteristics of high temperature gas cooled reactors (HTGR) at that time, the seismic classification of commercial light water reactors (LWR) was applied to HTTR. However, the subsequent operation experiences and test results using HTTR made it clear that the seismic classification of commercial LWR was somewhat too conservative for the HTGR. As a result, Class S facilities were downgraded compared to the commercial LWR. Moreover, the validity of the new seismic classification is confirmed. In June 2020, the Nuclear Regulatory Authority approved that the result of the seismic classification conformed to the standard rules of the reactor installation change.

Journal Articles

Development of dose estimation method using wild animal teeth for low dose exposure

Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.

KEK Proceedings 2021-2, p.91 - 96, 2021/12

We examined whether the ESR dose estimation method could be applied to wild Japanese macaque. In this work, we investigated the enamel preparation protocol and the analytical method of the ESR spectra.

Journal Articles

Phase transition and domain formation in ferroaxial crystals

Hayashida, Takeshi*; Uemura, Yohei*; Kimura, Kenta*; Matsuoka, Satoshi*; Hagihara, Masato; Hirose, Sakyo*; Morioka, Hitoshi*; Hasegawa, Tatsuo*; Kimura, Tsuyoshi*

Physical Review Materials (Internet), 5(12), p.124409_1 - 124409_10, 2021/12

Journal Articles

Coexistence of magnetoelectric and antiferroelectric-like orders in Mn$$_{3}$$Ta$$_{2}$$O$$_{8}$$

Kimura, Kenta*; Yagi, Naoki*; Hasegawa, Shunsuke*; Hagihara, Masato; Miyake, Atsushi*; Tokunaga, Masashi*; Cao, H.*; Masuda, Takatsugu*; Kimura, Tsuyoshi*

Inorganic Chemistry, 60(20), p.15078 - 15084, 2021/10

Journal Articles

Assessment of radiation doses to off-site responders in TEPCO Fukushima Daiichi Nuclear Power Station Accident

Shimada, Kazumasa; Iijima, Masashi*; Watanabe, Masatoshi*; Takahara, Shogo

Proceedings of Asian Symposium on Risk Assessment and Management 2021 (ASRAM 2021) (Internet), 17 Pages, 2021/10

The radiation doses received by the off-site responders in the Fukushima Daiichi Nuclear Power Station accident were assessed. Atmospheric dispersion simulation was conducted with the source term of the previous research to calculate the atmospheric concentration and ground surface deposition in the municipalities where off-site responders actives. The external exposure dose from cloudshine and groundshine, the internal exposure dose due to inhalation of radioactive plume and resuspended radio nuclei, and the temporal and spatial distribution within each municipality were assessed. As a result of comparing the assessed values of the external exposure dose with the measured values of the personal dosimeter, the measured values were within the assessed range. As a result of our assessment with internal dose exposure, if the exposures occurred without protective measures, the potential daily effective dose in the period between 12 and 31 March 2011 were several tens mSv per day or more in the relatively high dose area. Therefore, to keep the doses received by the responders below the reference level of 20 mSv recommended by the ICRP, it is necessary to ensure that the protective measures for internal exposures such as masks are taken, and to manage the time spent for their activity at least daily.

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

Chemical characterization of a volatile dubnium compound, DbOCl$$_3$$

Chiera, N. M.*; Sato, Tetsuya; Eichler, R.*; Tomitsuka, Tomohiro; Asai, Masato; Adachi, Sadia*; Dressler, R.*; Hirose, Kentaro; Inoue, Hiroki*; Ito, Yuta; et al.

Angewandte Chemie; International Edition, 60(33), p.17871 - 17874, 2021/08

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

The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on-line gas phase chromatography technique, in the temperature range 350 - 600 $$^circ$$C. Under the exact same chemical conditions, comparative studies with the lighter homologs of group-5 in the Periodic Table clearly indicate the volatility sequence being NbOCl$$_3 > $$ TaOCl$$_3 geq$$ DbOCl$$_3$$. From the obtained experimental results, thermochemical data for DbOCl$$_3$$ were derived. The present study delivers reliable experimental information for theoretical calculations on the chemical properties of transactinides.

Journal Articles

A Statistical approach for modeling the effect of hot press conditions on the mechanical strength properties of HTGR fuel elements

Aihara, Jun; Kuroda, Masatoshi*; Tachibana, Yukio

Proceedings of 28th International Conference on Nuclear Engineering; Nuclear Energy the Future Zero Carbon Power (ICONE 28) (Internet), 9 Pages, 2021/08

To maintain the structural integrity of fuel elements for a high-temperature gas-cooled reactor (HTGR) under disaster conditions, strong and oxidation-resistant fuel elements should be further developed. The HTGR fuel elements employ a hot-pressed silicon carbide (SiC)/carbon (C) mixed matrix to improve the oxidative resistance. Hot-press conditions such as pressure, temperature, and duration would be one of the factors that affect the strength of the HTGR fuel elements. To identify the optimal hot-press conditions for preparing the high-strength fuel elements, modelling their effects on the mechanical-strength properties of the HTGR fuel elements should be evaluated quantitatively. In this study, the response surface model, which represents the relationship between the hot-press conditions and the mechanical-strength properties, has been constructed by introducing statistical design-of-experiment approaches.

Journal Articles

Charge-density-wave order and multiple magnetic transitions in divalent europium compound EuAl$$_4$$

Kaneko, Koji; Kawasaki, Takuro; Nakamura, Ai*; Munakata, Koji*; Nakao, Akiko*; Hanashima, Takayasu*; Kiyanagi, Ryoji; Ohara, Takashi; Hedo, Masato*; Nakama, Takao*; et al.

Journal of the Physical Society of Japan, 90(6), p.064704_1 - 064704_6, 2021/06

 Times Cited Count:2 Percentile:72.06(Physics, Multidisciplinary)

Journal Articles

Effect of grain boundary on the friction coefficient of pure Fe under the oil lubrication

Adachi, Nozomu*; Matsuo, Yasutaka*; Todaka, Yoshikazu*; Fujimoto, Mikiya*; Hino, Masahiro*; Mitsuhara, Masatoshi*; Oba, Yojiro; Shiihara, Yoshinori*; Umeno, Yoshitaka*; Nishida, Minoru*

Tribology International, 155, p.106781_1 - 106781_9, 2021/03

 Times Cited Count:0 Percentile:0(Engineering, Mechanical)

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

Strong lattice anharmonicity exhibited by the high-energy optical phonons in thermoelectric material

Wu, P.*; Fan, F.-R.*; Hagihara, Masato*; Kofu, Maiko; Peng, K.*; Ishikawa, Yoshihisa*; Lee, S.*; Honda, Takashi*; Yonemura, Masao*; Ikeda, Kazutaka*; et al.

New Journal of Physics (Internet), 22(8), p.083083_1 - 083083_9, 2020/08

 Times Cited Count:2 Percentile:51.78(Physics, Multidisciplinary)

Thermoelectric material SnSe has aroused world-wide interests in the past years, and its inherent strong lattice anharmonicity is regarded as a crucial factor for its outstanding thermoelectric performance. However, the understanding of lattice anharmonicity in SnSe system remains inadequate, especially regarding how phonon dynamics are affected by this behavior. In this work, we present a comprehensive study of lattice dynamics on Na$$_{0.003}$$Sn$$_{0.997}$$Se$$_{0.9}$$S$$_{0.1}$$ by means of neutron total scattering, inelastic neutron scattering, Raman spectroscopy as well as frozen-phonon calculations. Lattice anharmonicity is evidenced by pair distribution function, inelastic neutron scattering and Raman measurements. By separating the effects of thermal expansion and multi-phonon scattering, we found that the latter is very significant in high-energy optical phonon modes. The strong temperature-dependence of these phonon modes indicate the anharmonicity in this system. Moreover, our data reveals that the linewidths of high-energy optical phonons become broadened with mild doping of sulfur. Our studies suggest that the thermoelectric performance of SnSe could be further enhanced by reducing the contributions of high-energy optical phonon modes to the lattice thermal conductivity via phonon engineering.

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