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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

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2021)

Ishimaru, Tsuneari; Kokubu, Yoko; Shimada, Koji; Shimada, Akiomi; Niwa, Masakazu; Watanabe, Takahiro; Sueoka, Shigeru; Yokoyama, Tatsunori; Fujita, Natsuko; Ogita, Yasuhiro; et al.

JAEA-Review 2021-012, 48 Pages, 2021/08


This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2021. The objectives and contents in fiscal year 2021 are described in detail based on the JAEA 3rd Medium- and Long-term Plan (fiscal years 2015-2021). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. The plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

Journal Articles

Gapless spin liquid in a square-kagome lattice antiferromagnet

Fujihara, Masayoshi*; Morita, Katsuhiro*; Mole, R.*; Mitsuda, Setsuo*; Toyama, Takami*; Yano, Shinichiro*; Yu, D.*; Sota, Shigetoshi*; Kuwai, Tomohiko*; Koda, Akihiro*; et al.

Nature Communications (Internet), 11(1), p.3429_1 - 3429_7, 2020/07

 Times Cited Count:8 Percentile:81.73(Multidisciplinary Sciences)

Journal Articles

Intercomparison of numerical atmospheric dispersion prediction models for emergency response to emissions of radionuclides with limited source information in the Fukushima Dai-ichi Nuclear Power Plant accident

Iwasaki, Toshiki*; Sekiyama, Tsuyoshi*; Nakajima, Teruyuki*; Watanabe, Akira*; Suzuki, Yasushi*; Kondo, Hiroaki*; Morino, Yu*; Terada, Hiroaki; Nagai, Haruyasu; Takigawa, Masayuki*; et al.

Atmospheric Environment, 214, p.116830_1 - 116830_11, 2019/10

 Times Cited Count:4 Percentile:39.15(Environmental Sciences)

The utilization of numerical atmospheric dispersion prediction (NDP) models for accidental discharge of radioactive substances was recommended by a working group of the Meteorological Society of Japan. This paper is to validate the recommendation through NDP model intercomparison in the accidental release from the Fukushima Dai-ichi Nuclear Power Plant in 2011. Emission intensity is assumed to be constant during the whole forecast period for the worst-case scenario unless time sequence of emission is available. We expect to utilize forecasts of surface air contaminations for preventions of inhalations of radioactive substances, and column-integrated amounts for mitigation of radiation exposure associated with wet deposition. Although NDP forecasts have ensemble spread, they commonly figure out relative risk in space and time. They are of great benefit to disseminating effective warnings to public without failure. The multi-model ensemble technique may be effective to improve the reliability.

Journal Articles

Application of analysis for assembly of integrated components to steel member connections towards seismic safety assessment of plant structures

Nishida, Akemi; Murakami, Takahiro*; Satoda, Akira*; Asano, Yuya*; Guo, Z.*; Matsukawa, Keisuke*; Oshima, Masami*; Nakajima, Norihiro

Proceedings of 25th International Conference on Structural Mechanics in Reactor Technology (SMiRT-25) (USB Flash Drive), 10 Pages, 2019/08

Exhaustive studies on external events that may pose a threat to the structures of nuclear facilities and evaluations of the structural integrities are critical to safety. One of the components that greatly influence the behavior of the plant structure is the connection of structural members. In particular, the modeling of the connections has relied on empirical methods, and been conservatively designed and evaluated by considering them as pinned or rigid connections. Therefore, in this research, we have aimed to develop a connection modeling method that reproduces more realistic behavior by utilizing a three-dimensional model of the connection. As the first step of this research, we planned to determine the stiffness of the connections of steel structural members. The results confirmed that the connection can be regarded as a partially-restrained connection depending on the connection specifications of the structure, and the prospects for realistic stiffness evaluation of the connection were determined.

Journal Articles

Electrical and crystallographic study of an electrothermodynamic cycle for a waste heat recovery

Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; et al.

Advanced Sustainable Systems (Internet), 2(11), p.1800067_1 - 1800067_8, 2018/11

 Times Cited Count:1 Percentile:11.84(Green & Sustainable Science & Technology)

Journal Articles

Pyroelectric power generation with ferroelectrics (1-x)PMN-xPT

Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; et al.

Ferroelectrics, 512(1), p.92 - 99, 2017/08

 Times Cited Count:6 Percentile:41.1(Materials Science, Multidisciplinary)

Journal Articles

Relationship between the material properties and pyroelectric-generating performance of PZTs

Yamanaka, Satoru*; Kim, J.*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Yamada, Noboru*; et al.

Advanced Sustainable Systems (Internet), 1(3-4), p.1600020_1 - 1600020_6, 2017/04

no abstracts in English

Journal Articles

Tritium decontamination of contaminated system with tritiated heavy water by drying treatment

Kadowaki, Haruhiko; Matsushima, Akira; Nakajima, Yoshiaki

Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 6 Pages, 2016/06

Advanced thermal reactor "FUGEN" is a heavy water-moderated boiling light water-cooled pressure tube-type reactor. Because tritium had been generated in the heavy water during the reactor operation, the heavy water system and helium system were contaminated by tritium. The chemical form of the tritium was water molecule in FUGEN. Air-through drying and vacuum drying were applied to the system drying, and it was demonstrated that both methods were effective for drying treatment of heavy water in system. Helium system, low-contamination and non inclusion, could finish the vacuum drying rapidly. However, Heavy water purification system needed long period for drying treatment. The result showed that it needed long period to dry up if the objects include the adsorbent of water such as alumina pellet, resin and silica gel. But it can be accelerated by replacement absorbed heavy water to light water from the result of drying treatment of the rotary type dehumidifier.

Journal Articles

Photoelectron diffraction from laser-aligned molecules with X-ray free-electron laser pulses

Nakajima, Kyo*; Teramoto, Takahiro*; Akagi, Hiroshi; Fujikawa, Takashi*; Majima, Takuya*; Minemoto, Shinichiro*; Ogawa, Kanade*; Sakai, Hirofumi*; Togashi, Tadashi*; Tono, Kensuke*; et al.

Scientific Reports (Internet), 5, p.14065_1 - 14065_11, 2015/09

 Times Cited Count:29 Percentile:83.61(Multidisciplinary Sciences)

We report on the measurement of deep inner-shell 2p X-ray photoelectron diffraction (XPD) patterns from laser-aligned I$$_{2}$$ molecules using X-ray free-electron laser (XFEL) pulses. The XPD patterns of the I$$_{2}$$ molecules, aligned parallel to the polarization vector of the XFEL, were well matched with our theoretical calculations. Further, we propose a criterion for applying our molecular-structure-determination methodology to the experimental XPD data. In turn, we have demonstrated that this approach is a significant step toward the time-resolved imaging of molecular structures.

Journal Articles

Novel electrothermodynamic power generation

Kim, Y.*; Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Ogawa, Takashi*; Serizawa, Takeshi*; Tanaka, Hirohisa*; Baba, Masaaki*; Fukuda, Tatsuo; Yoshii, Kenji; et al.

Advanced Energy Materials, 5(13), p.1401942_1 - 1401942_6, 2015/07

 Times Cited Count:8 Percentile:41.84(Chemistry, Physical)

An innovative electro-thermodynamic cycle based on temporal temperature variations using pyroelectric effect has been presented. Practical energy is successfully generated in both $textit{in-situ}$ synchrotron X-ray diffraction measurements under controlled conditions and $textit{Operando}$ real engine dynamometer experiments. The main generating origin is revealed as a combination of a crystal structure change and dipole change phenomenon corresponds to the temperature variation. In particular, the electric field induced 180$$^circ$$ domain switching extremely improves generating power, and the true energy breakeven with temperature variation is firstly achieved.

Journal Articles

Development of in-reactor observation system using Cherenkov light(VI)

Takeuchi, Tomoaki; Yamamoto, Keiichi; Otsuka, Noriaki; Shibata, Hiroshi; Shibata, Akira; Takemoto, Noriyuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Unesaki, Hironobu*; Fujihara, Yasuyuki*; et al.

KURRI Progress Report 2014, P. 108, 2015/07

Investigation of a relation between output power and brightness of Cherenkov light of a specific fuel element at KUR by a CCD camera was performed due to a development of a real-time in-core measurement technique using Cherenkov light. The results indicate that the inhomogeneous distribution of output power and the shadow of the control-rod guide tubes and the other irradiation equipment have significant effects on the brightness of the Cherenkov light. These effects could be suppressed by using a number of cameras located at various positions.

Journal Articles

Development of in-reactor observation system using Cherenkov light, 5

Otsuka, Noriaki; Takeuchi, Tomoaki; Yamamoto, Keiichi; Shibata, Akira; Kimura, Nobuaki; Takemoto, Noriyuki; Tanimoto, Masataka; Tsuchiya, Kunihiko; Sano, Tadafumi*; Unesaki, Hironobu*; et al.

KURRI Progress Report 2013, P. 215, 2014/10

Investigation of a relation between reactor power and brightness of Cherenkov light at Kyoto University Research reactor (KUR) by a CCD camera was performed due to a development of a real-time in-core measurement technique using Cherenkov light. Analyzing the brightness value of individual RGB color component at each pixel, some of the G and B brightness values reached the maximum value of 8-bit binary number, i.e. 255, above about 2-3 MW. Therefore, we corrected the G and B brightness values by the R signals whose brightness value did not saturate even at 5 MW, the maximum reactor power of KUR. Then, the total brightness value was in proportion to the reactor power after the correction. These results indicate the reactor power can be estimated by the observation of Cherenkov light.

Journal Articles

Development of in-reactor observation system using Cherenkov light, 4

Kimura, Nobuaki; Takeuchi, Tomoaki; Shibata, Akira; Takemoto, Noriyuki; Kimura, Akihiro; Naka, Michihiro; Nishikata, Kaori; Tanimoto, Masataka; Tsuchiya, Kunihiko; Sano, Tadafumi*; et al.

KURRI Progress Report 2012, P. 209, 2013/10

In research reactors, CCD cameras are used to observe reactor core for reactor operation management, e.g. to prevent debris from falling. In order to measure the reactor power and fuel burnup exactly by means of observation of Cherenkov light, the development of the on-line measurement device started in 2009. In this study, the wavelength and the absolute irradiance of the Cherenkov light were measured by a spectrometer, and the Cherenkov light was observed by the CCD camera. As a result, the measurement value is good agreement with the nominal value. On the other hand, the value by the visible imaging system was obtained the same tendency of nominal transmittance value of ND-filters.

Journal Articles

Visualization of $$gamma$$H2AX foci caused by heavy ion particle traversal; Distribution between core track versus non-track damage

Nakajima, Nakako*; Brunton, H.*; Watanabe, Ritsuko; Shrikhande, A.*; Hirayama, Ryoichi*; Matsufuji, Naruhiro*; Fujimori, Akira*; Murakami, Takeshi*; Okayasu, Ryuichi*; Jeggo, P.*; et al.

PLOS ONE (Internet), 8(8), p.e70107_1 - e70107_14, 2013/08

 Times Cited Count:48 Percentile:89.39(Multidisciplinary Sciences)

Heavy particle irradiation can produce complex DNA double strand breaks (DSBs) within the particle trajectory. Additionally, secondary electrons, termed delta-electrons, can create low linear energy transfer (LET) damage distant from the track. Using imaging with deconvolution, we show that at 8 hours after exposure to Fe ions, $$gamma$$H2AX foci forming at DSBs within the particle track are large and encompass multiple smaller and closely localised foci, which we designate as clustered $$gamma$$H2AX foci. We also identified simple $$gamma$$H2AX foci distant from the track. They are rapidly repaired. Clustered $$gamma$$H2AX foci induced by heavy particle radiation cause prolonged checkpoint arrest compared to simple $$gamma$$H2AX foci. However, mitotic entry was observed when $$sim$$10 clustered foci remain. Thus, cells can progress into mitosis with multiple clusters of DSBs following the traversal of a heavy particle.

Journal Articles

Effects of Mg, Ag, and Al substitutions on magnetic excitations in the triangular-lattice antiferromagnet CuCrO$$_{2}$$

Kajimoto, Ryoichi; Nakajima, Kenji; Kawamura, Seiko; Inamura, Yasuhiro; Kakurai, Kazuhisa; Hokazono, Takahisa*; Ozono, Akira*; Okuda, Tetsuji*

Journal of the Physical Society of Japan, 82(5), p.054702_1 - 054702_6, 2013/05

 Times Cited Count:4 Percentile:36.94(Physics, Multidisciplinary)

Journal Articles

Temperature and Ag doping effect on magnetic excitations in the quasi-two-dimensional triangular lattice antiferromagnet CuCrO$$_2$$ studied by inelastic neutron scattering

Kajimoto, Ryoichi; Nakajima, Kenji; Kawamura, Seiko; Inamura, Yasuhiro; Kakurai, Kazuhisa; Arai, Masatoshi; Hokazono, Takahisa*; Ozono, Akira*; Okuda, Tetsuji*

Journal of the Physical Society of Japan, 79(12), p.123705_1 - 123705_4, 2010/12

 Times Cited Count:21 Percentile:74(Physics, Multidisciplinary)

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

Journal Articles

Strong carrier-scattering in iron-pnictide superconductors ${it Ln}$FeAsO$$_{1-y}$$ (${it Ln}$ = La and Nd) obtained from charge transport experiments

Ishida, Shigeyuki*; Nakajima, Masamichi*; Tomioka, Yasuhide*; Ito, Toshimitsu*; Miyazawa, Kiichi*; Kito, Hijiri*; Lee, C.-H.*; Ishikado, Motoyuki; Shamoto, Shinichi; Iyo, Akira*; et al.

Physical Review B, 81(9), p.094515_1 - 094515_6, 2010/03

 Times Cited Count:21 Percentile:67.68(Materials Science, Multidisciplinary)

Characteristic normal-state charge transport is found in the oxygen-deficient iron-arsenides ${it Ln}$FeAsO$$_{1-y}$$ (${it Ln}$: La and Nd) with the highest ${it T}$ $$_{c}$$'s among known Fe-based superconductors. The effect of "doping" in this system is mainly on the carrier scattering, quite distinct from that in high-${it T}$ $$_{c}$$ cuprates. In the superconducting regime of the La system with maximum ${it T}$ $$_{c}$$ = 28 K, the low-temperature resistivity is dominated by a ${it T}$ $$^{2}$$ term. On the other hand, in the Nd system with ${it T}$ $$_{c}$$ higher than 40 K, the carriers are subject to stronger scattering showing ${it T}$ -linear resistivity and small magnetoresistance. Such strong scattering appears crucial for high-${it T}$ $$_{c}$$ superconductivity in the iron-based system.

Journal Articles

Evaluation of high-temperature tensile properties of reduced activation ferritic steels by small punch test

Nakata, Toshiya; Komazaki, Shinichi*; Nakajima, Motoki*; Kono, Yutaka*; Tanigawa, Hiroyasu; Shiba, Kiyoyuki; Koyama, Akira*

Nihon Kinzoku Gakkai-Shi, 70(8), p.642 - 645, 2006/08

 Times Cited Count:4 Percentile:36.15(Metallurgy & Metallurgical Engineering)

no abstracts in English

47 (Records 1-20 displayed on this page)