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Journal Articles

First observation of $$^{28}$$O

Kondo, Yosuke*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; Baba, Hidetada*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.

Nature, 620(7976), p.965 - 970, 2023/08

no abstracts in English

Journal Articles

Intruder configurations in $$^{29}$$Ne at the transition into the island of inversion; Detailed structure study of $$^{28}$$Ne

Wang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.

Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08

Detailed $$gamma$$-ray spectroscopy of the exotic neon isotope $$^{28}$$Ne has been performed using the one-neutron removal reaction from $$^{29}$$Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for $$^{28}$$Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.

Journal Articles

Layer-number-independent two-dimensional ferromagnetism in Cr$$_3$$Te$$_4$$

Wang, Y.*; Kajihara, Shun*; Matsuoka, Hideki*; Saika, B. K.*; Yamagami, Kohei*; Takeda, Yukiharu; Wadachi, Hiroki*; Ishizaka, Kyoko*; Iwasa, Yoshihiro*; Nakano, Masaki*

Nano Letters, 22(24), p.9964 - 9971, 2022/12

 Times Cited Count:2 Percentile:79.58(Chemistry, Multidisciplinary)

Journal Articles

Spin-orbit-induced Ising ferromagnetism at a van der Waals interface

Matsuoka, Hideki*; Barnes, S. E.*; Ieda, Junichi; Maekawa, Sadamichi; Bahramy, M. S.*; Saika, B. K.*; Takeda, Yukiharu; Wadachi, Hiroki*; Wang, Y.*; Yoshida, Satoshi*; et al.

Nano Letters, 21(4), p.1807 - 1814, 2021/02

 Times Cited Count:9 Percentile:73.98(Chemistry, Multidisciplinary)

Journal Articles

Spallation and fragmentation cross sections for 168 MeV/nucleon $$^{136}$$Xe ions on proton, deuteron, and carbon targets

Sun, X. H.*; Wang, H.*; Otsu, Hideaki*; Sakurai, Hiroyoshi*; Ahn, D. S.*; Aikawa, Masayuki*; Fukuda, Naoki*; Isobe, Tadaaki*; Kawakami, Shunsuke*; Koyama, Shumpei*; et al.

Physical Review C, 101(6), p.064623_1 - 064623_12, 2020/06

 Times Cited Count:5 Percentile:53.56(Physics, Nuclear)

The spallation and fragmentation reactions of $$^{136}$$Xe induced by proton, deuteron and carbon at 168 MeV/nucleon were studied at RIKEN Radioactive Isotope Beam Factory via the inverse kinematics technique. The cross sections of the lighter products are larger in the carbon-induced reactions due to the higher total kinetic energy of carbon. The energy dependence was investigated by comparing the newly obtained data with previous results obtained at higher reaction energies. The experimental data were compared with the results of SPACS, EPAX, PHITS and DEURACS calculations. These data serve as benchmarks for the model calculations.

Journal Articles

Study on plutonium burner high temperature gas-cooled reactor in Japan; Introduction scenario, reactor safety and fabrication tests of the 3S-TRISO fuel

Ueta, Shohei; Mizuta, Naoki; Fukaya, Yuji; Goto, Minoru; Tachibana, Yukio; Honda, Masaki*; Saiki, Yohei*; Takahashi, Masashi*; Ohira, Koichi*; Nakano, Masaaki*; et al.

Nuclear Engineering and Design, 357, p.110419_1 - 110419_10, 2020/02

 Times Cited Count:1 Percentile:12.47(Nuclear Science & Technology)

The concept of a plutonium (Pu) burner HTGR is proposed to incarnate highly-effective Pu utilization by its inherent safety features. The security and safety fuel (3S-TRISO fuel) employs the coated fuel particle with a fuel kernel made of plutonium dioxide (PuO$$_{2}$$) and yttria stabilized zirconia (YSZ) as an inert matrix. This paper presents feasibility study of Pu burner HTGR and R&D on the 3S-TRISO fuel.

Journal Articles

Intrinsic 2D ferromagnetism in V$$_{5}$$Se$$_{8}$$ epitaxial thin films

Nakano, Masaki*; Wang, Y.*; Yoshida, Satoshi*; Matsuoka, Hideki*; Majima, Yuki*; Ikeda, Keisuke*; Hirata, Yasuyuki*; Takeda, Yukiharu; Wadachi, Hiroki*; Kohama, Yoshimitsu*; et al.

Nano Letters, 19(12), p.8806 - 8810, 2019/12

 Times Cited Count:46 Percentile:91.62(Chemistry, Multidisciplinary)

Journal Articles

Conceptual study of a plutonium burner high temperature gas-cooled reactor with high nuclear proliferation resistance

Goto, Minoru; Demachi, Kazuyuki*; Ueta, Shohei; Nakano, Masaaki*; Honda, Masaki*; Tachibana, Yukio; Inaba, Yoshitomo; Aihara, Jun; Fukaya, Yuji; Tsuji, Nobumasa*; et al.

Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.507 - 513, 2015/09

A concept of a plutonium burner HTGR named as Clean Burn, which has a high nuclear proliferation resistance, had been proposed by Japan Atomic Energy Agency. In addition to the high nuclear proliferation resistance, in order to enhance the safety, we propose to introduce PuO$$_{2}$$-YSZ TRISO fuel with ZrC coating to the Clean Burn. In this study, we conduct fabrication tests aiming to establish the basic technologies for fabrication of PuO$$_{2}$$-YSZ TRISO fuel with ZrC coating. Additionally, we conduct a quantitative evaluation of the security for the safety, a design of the fuel and the reactor core, and a safety evaluation for the Clean Burn to confirm the feasibility. This study is conducted by The University of Tokyo, Japan Atomic Energy Agency, Fuji Electric Co., Ltd., and Nuclear Fuel Industries, Ltd. It was started in FY2014 and will be completed in FY2017, and the first year of the implementation was on schedule.

Journal Articles

New PbTiO$$_{3}$$-type giant tetragonal compound Bi$$_{2}$$ZnVO$$_{6}$$ and its stability under pressure

Yu, R.*; Hojo, Hajime*; Oka, Kengo*; Watanuki, Tetsu; Machida, Akihiko; Shimizu, Keisuke*; Nakano, Kiho*; Azuma, Masaki*

Chemistry of Materials, 27(6), p.2012 - 2017, 2015/03

 Times Cited Count:26 Percentile:62.78(Chemistry, Physical)

no abstracts in English

Journal Articles

Suppression of temperature hysteresis in negative thermal expansion compound BiNi$$_{1-x}$$Fe$$_{x}$$O$$_{3}$$ and zero-thermal expansion composite

Nabetani, Koichiro*; Muramatsu, Yuya*; Oka, Kengo*; Nakano, Kiho*; Hojo, Hajime*; Mizumaki, Masaichiro*; Agui, Akane; Higo, Yuji*; Hayashi, Naoaki*; Takano, Mikio*; et al.

Applied Physics Letters, 106(6), p.061912_1 - 061912_5, 2015/02

 Times Cited Count:58 Percentile:89.01(Physics, Applied)

Negative thermal expansion (NTE) of BiNi$$_{1_x}$$Fe$$_x$$O$$_3$$ is investigated by dilatometric curves, synchrotron X-ray diffraction, and X-ray absorption spectroscopy. All samples (x=0.05-0.15) shows large NTE with the coefficient of linear thermal expansion which induced by charge transfer between Bi$$^{5+}$$ and Ni$$^{2+}$$ in the controlled temperature range near room temperature. Compared with Bi$$_{1_x}$$Ln$$_x$$NiO$$_3$$ (Ln: rare-earth elements), the thermal hysteresis that causes a problem for practical application is suppressed because random distribution of Fe in the Ni site changes the first order transition to second order-like transition.

Journal Articles

Carbon transport and fuel retention in JT-60U with higher temperature operation based on postmortem analysis

Yoshida, Masafumi; Tanabe, Tetsuo*; Adachi, Ayumu*; Hayashi, Takao; Nakano, Tomohide; Fukumoto, Masakatsu; Yagyu, Junichi; Miyo, Yasuhiko; Masaki, Kei; Itami, Kiyoshi

Journal of Nuclear Materials, 438, p.S1261 - S1265, 2013/07

 Times Cited Count:6 Percentile:44.21(Materials Science, Multidisciplinary)

Fuel retention rates and carbon re-deposition rates in the plasma shadowed areas in JT-60U were measured. Distributions of the fuel retention as well as the carbon re-deposition in the whole in-vessel of a large tokamak were clarified for the first time in the world. The fuel retention in the plasma shadowed areas was about two times larger than that in the carbon re-deposited layers on the plasma facing surface, although the amount of the carbon re-deposited on the plasma shadowed areas were about a half of that on the plasma facing surface, because of relatively lower temperature in the shadow areas causing higher hydrogen saturation concentration in the carbon re-deposited layers. The total fuel retention rate in JT-60U, including previously measured for all plasma facing areas, was evaluated to be 1.3$$times$$10$$^{20}$$ H+Ds$$^{-1}$$, which was lower than that in other devices, due to probably to higher temperature operation in JT-60U.

Journal Articles

Hydrogen isotopes retention in gaps at the JT-60U first wall tiles

Yoshida, Masafumi; Tanabe, Tetsuo*; Hayashi, Takao; Nakano, Tomohide; Fukumoto, Masakatsu; Yagyu, Junichi; Miyo, Yasuhiko; Masaki, Kei; Itami, Kiyoshi

Fusion Science and Technology, 63(1T), p.367 - 370, 2013/05

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

In this study, the retentions of hydrogen isotopes (H and D) in the gaps in JT-60U are clarified. Carbon tiles used in 1992-2004 were poloidally and toroidally taken out from outboard first wall in JT-60U to measure the retentions. The H and D retentions in the samples were measured by thermal desorption spectrometry (TDS). The H+D retention in the top side was higher than that of the bottom side, which might be due to thicker re-deposited carbon layers on the surface of the top side. The retentions in the surface of the side surfaces were slightly lower than that in the plasma facing surface where the retention was saturated to be 3-4e22 atoms/m$$^{2}$$. The retention rate was evaluated to be 3e17 H+D atoms/m$$^{2}$$/s from the measured retentions in two different discharge times by assuming the retention to increase linearly with the discharge time.

Journal Articles

Deuterium retention in tungsten coating on the CFC tiles exposed to JT-60U divertor plasmas

Fukumoto, Masakatsu; Nakano, Tomohide; Masaki, Kei; Itami, Kiyoshi; Ueda, Yoshio*; Tanabe, Tetsuo*

Journal of Plasma and Fusion Research SERIES, Vol.9, p.369 - 374, 2010/08

no abstracts in English

Journal Articles

Report on ITPA meetings, 24

Idomura, Yasuhiro; Yoshida, Maiko; Yagi, Masatoshi*; Tanaka, Kenji*; Hayashi, Nobuhiko; Sakamoto, Yoshiteru; Tamura, Naoki*; Oyama, Naoyuki; Urano, Hajime; Aiba, Nobuyuki; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(12), p.952 - 955, 2008/12

no abstracts in English

Journal Articles

Prediction accuracy improvement of neutronic characteristics of a breeding light water reactor core by extended bias factor methods with use of FCA-XXII-1 critical experiments

Kugo, Teruhiko; Ando, Masaki; Kojima, Kensuke; Fukushima, Masahiro; Mori, Takamasa; Nakano, Yoshihiro; Okajima, Shigeaki; Kitada, Takanori*; Takeda, Toshikazu*

Journal of Nuclear Science and Technology, 45(4), p.288 - 303, 2008/04

 Times Cited Count:6 Percentile:40.16(Nuclear Science & Technology)

The effectiveness of the extended bias factor methods, the LC and PE methods, is numerically investigated by applying them to a breeding light water reactor core as a target core with use of FCA-XXII-1 critical experiments. The present study numerically verifies the features of the extended bias factor methods. Both the methods can improve the prediction accuracy the most by using all the experiments. The PE method always improves the prediction accuracy with any combination of experiments. The PE method is always superior to the LC method for improvement of the prediction accuracy. From the present study, the followings are found. The experiments on multiplication factor are more applicable to a reaction rate ratio of $$^{238}$$U capture to $$^{239}$$Pu fission (C28/F49) of the target core than the experiments on C28/F49. Combinations of the experiments on multiplication factor is more effective to a void reactivity of the target core than those of the experiments on void reactivity though those on void reactivity are superior to those on multiplication factors in the case of using a single experiment. From these results, we conclude that the experiments on multiplication factor are more effective than the other experiments for all the neutronic characteristics of the target core. From these results, it is concluded that the PE method is promising to complement full mockup experiments for various future nuclear systems by using a number of existing and future benchmark experiments.

Journal Articles

Impact of wall saturation on particle control in long and high-power-heated discharges in JT-60U

Nakano, Tomohide; Asakura, Nobuyuki; Takenaga, Hidenobu; Kubo, Hirotaka; Miura, Yukitoshi; Shimizu, Katsuhiro; Konoshima, Shigeru; Masaki, Kei; Higashijima, Satoru; JT-60 Team

Nuclear Fusion, 46(5), p.626 - 634, 2006/05

 Times Cited Count:20 Percentile:57.39(Physics, Fluids & Plasmas)

In order to understand plasma-wall interactions in a long time scale, the discharge pulse length has been extended from 15 s to 65 s, with the NB-heating duration extended to 30 s. Nearly-saturation of the divertor plates was observed in the latter half of long pulse ELMy H-mode discharges. Particle sink into the divertor plates gradually decreased, and subsequently, wall-pumping efficiency became zero. This wall saturation resulted in a rise of the main plasma density without any auxiliary particle supply besides NB with divertor-pumping. Even when the total injected energy reached up to $$sim$$ 350 MJ in a discharge, neither sudden increase of carbon generation such as carbon bloom nor increase of the dilution of the main plasma was observed.

JAEA Reports

Evaluation of prediction accuracy for $$^{238}$$U Doppler effect measured in FCA LWR simulating cores; Analysis with JENDL-3.3 library and SRAC system (Joint research)

Kawasaki, Kenji*; Ando, Masaki; Okajima, Shigeaki; Fukushima, Masahiro; Nakano, Makoto*; Matsumoto, Hideki*

JAEA-Research 2006-008, 40 Pages, 2006/03

JAEA-Research-2006-008.pdf:3.6MB

Analysis was performed to evaluate prediction accuracy of a neutronics code system for thermal reactor; the SRAC system with the use of the latest nuclear data library JENDL-3.3 for the $$^{238}$$U Doppler effect measured in the uranium fueled (FCA-XXI-1D2) and MOX fueled (XXII-1 series) cores. The results of the analysis with the diffusion theory showed overestimation by up to +11%. In relatively soft neutron spectra, however, the calculated values agreed with the experimental ones within the experimental errors.

Journal Articles

Study of global wall saturation mechanisms in long-pulse ELMy H-mode discharges on JT-60U

Takenaga, Hidenobu; Nakano, Tomohide; Asakura, Nobuyuki; Kubo, Hirotaka; Konoshima, Shigeru; Shimizu, Katsuhiro; Tsuzuki, Kazuhiro; Masaki, Kei; Tanabe, Tetsuo*; Ide, Shunsuke; et al.

Nuclear Fusion, 46(3), p.S39 - S48, 2006/03

 Times Cited Count:18 Percentile:52.52(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Enhanced ELMy H-mode performance with reduced toroidal field ripple in JT-60U

Oyama, Naoyuki; Urano, Hajime; Yoshida, Maiko; Takenaga, Hidenobu; Shinohara, Koji; Sakurai, Shinji; Masaki, Kei; Kamiya, Kensaku; Isayama, Akihiko; Suzuki, Takahiro; et al.

Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00

no abstracts in English

JAEA Reports

Measurement of doppler effect on resonance materials for ROX fuel using FCA

Ando, Masaki; Nakano, Yoshihiro; Okajima, Shigeaki; Kawasaki, Kenji

JAERI-Research 2003-029, 72 Pages, 2003/12

JAERI-Research-2003-029.pdf:3.41MB

The objectives of this study is to clarify calculation accuracy for the Doppler effect of the resonance materials; erbium (Er), tungsten (W) and thorium (ThO$$_{2}$$). Doppler effect measurements were carried out in a fast neutron spectrum (XX-2 core) and in an intermediate neutron spectrum (XXI-1D2 core) by the sample-heated and reactivity worth measurement method up to 800$$^{circ}$$C using FCA. The experiment was analyzed with the standard analysis method for fast reactor cores at FCA with the use of the JENDL-3.2. The SRAC system was also used to investigate the calculation accuracy of the system and to compare it with that of the FCA standard analysis method. The standard analysis method underestimated for the XX-2 core and agreed the experiments within the experimental errors for the XXI-1D2 core. The analysis with the SRAC system gave smaller values by 3%$$sim$$10% for the Er sample and bigger values by 2%$$sim$$5% for the W sample than the standard analysis method.

33 (Records 1-20 displayed on this page)