Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Fukaya, Yuji; Asano, Kazuhito; Sato, Hiroyuki; Ohashi, Hirofumi; Sakaba, Nariaki
JAEA-Review 2026-015, 10 Pages, 2026/06
JAEA-Review-2026-015.pdf:0.96MB
The Japan Atomic Energy Agency (JAEA) is developing SiC matrix fuel as a fuel to improve oxidation resistance. It is a simple manufacturing method called the slurry method, in which raw materials are dissolved in water, molded, and sintered, and are designed to pursue manufacturability in consideration of mass production. On the other hand, there is a patent in the U.S. for SiC matrix fuel, and it was expressed that there is a risk that the JAEA's SiC matrix fuel technology may infringe this patent, and it should be confirmed. In that case of infringement, it could become an obstacle to the social implementation of that technology. Therefore, in order to determine whether the SiC-based fuel for HTGR proposed by the JAEA would constitute a patent infringement against the aforementioned U.S. patent, JAEA requested a formal infringement evaluation from a major U.S. patent law firm. As a result, it was determined that the SiC-based fuel for high-temperature gas reactors proposed by the JAEA does not constitute a patent infringement against the aforementioned U.S. patent. This removed obstacles to the future deployment of the SiC matrix fuel proposed by the JAEA for high temperature gas-cooled reactors.
Tada, Kenichi
Kaku Deta Nyusu (Internet), (144), p.17 - 29, 2026/06
This document provides an overview of the international conference on reactor physics, Physor2026, and explains research presentations related to nuclear data for the Japanese nuclear data community.
Sakakibara, Ryotaro*; Terasawa, Tomoo; Kawauchi, Taizo*; Fukutani, Katsuyuki; Ito, Takahiro*; Norimatsu, Wataru*
Small Methods, 10(8), p.e01889_1 - e01889_12, 2026/04
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)Mori, Tetsuya; Oki, Shigeo
Nuclear Technology, 212(2), p.490 - 509, 2026/02
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)This study investigates the characteristics of the Doppler coefficient and sodium void reactivity of a burning fast reactor core concept, which was constructed in a previous study. This concept allows for multiple recyclings of plutonium and minor actinides (transuraniums (TRU)). TRU degradation due to multiple recycling deteriorates the reactivity coefficients through indirect effects, such as by hardening the neutron spectrum and steepening the energy gradient of neutron importance. Using silicon carbide (SiC) structural material improves the reactivity coefficient by causing an opposite indirect effect of TRU degradation. This improvement results not only from neutron spectrum softening due to the neutron moderation effect from 
C but also from the neutron leakage effect resulting from the low structural material density. The disadvantage of increased calculation uncertainty by using SiC structural material can be practically ignored. Furthermore, the burning core has Doppler coefficient enhancement characteristics by the moderated neutron reflection effect from outside the core. This characteristic has the potential to provide a new measure for reactivity coefficient deterioration due to TRU degradation. The reactivity coefficient characteristics clarified in this study can provide valuable knowledge for future detailed designs and design improvements of a TRU burning core.
Tada, Kenichi; Aizawa, Naoto*; Fujita, Tatsuya*; Fukushima, Masahiro; Pyeon, C. H.*
Journal of Nuclear Science and Technology, 63(1), p.1 - 2, 2026/01
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)This document is the preface to "Special Issue on Progressive Reactor Physics for Current and Future Challenges" published in the Journal of Nuclear Science and Technology.
CPham, V. H.; Kurata, Masaki; Nagae, Yuji; Ishibashi, Ryo*; Sasaki, Masana*
Corrosion Science, 255, p.113098_1 - 113098_9, 2025/10
Times Cited Count：5 Percentile：73.85(Materials Science, Multidisciplinary)Aihara, Jun; Ueta, Shohei; Honda, Masaki*; Kasahara, Seiji; Okamoto, Koji*
JAEA-Research 2024-012, 98 Pages, 2025/02
JAEA-Research-2024-012.pdf:32.24MB
Concept of Pu-burner high temperature gas-cooled reactor (HTGR) was proposed for the purpose of more safely reducing amount of recovered Pu. In Pu-burner HTGR concept, coated fuel particle (CFP), with ZrC coated yttria stabilized zirconia (YSZ) containing PuO
(PuO-YSZ) small particle and with tri-structural isotropic (TRISO) coating, is employed for very high burn-up and high nuclear proliferation resistance. ZrC layer is oxygen getter. In research project of Pu-burner HTGR carried out from fiscal year of 2014 to fiscal year of 2017, simulated CFPs were fabricated using Ce to simulate Pu. Moreover, simulated fuel compacts were fabricated using fabricated simulated CFPs. In this report, results of microstructural observation of CeO-YSZ and ZrC layer at each fabrication step are reported.
Meigo, Shinichiro; Yamaguchi, Yuji
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.853 - 858, 2024/10
no abstracts in English
Ishibashi, Ryo*; Hirosaka, Kazuma*; Yamana, Takashi*; Shibata, Masatoshi*; Sasaki, Masana*; Nemoto, Yoshiyuki; Hinoki, Tatsuya*
Proceedings of TopFuel 2024 (Internet), 9 Pages, 2024/10
Suyama, Kenya; Gunji, Satoshi; Watanabe, Tomoaki; Araki, Shohei; Fukuda, Kodai; Shimada, Kazuya; Fujita, Tatsuya; Ueki, Taro; Nguyen, H. H.
JAEA-Conf 2024-001, 40 Pages, 2024/07
JAEA-Conf-2024-001.pdf:1.28MB
JAEA-Conf-2024-001-appendix(CD-ROM).zip:163.97MB
The 12th International Conference on Nuclear Criticality Safety (ICNC2023) was held from October 1 to October 6, 2023, at the Sendai International Center (Aobayama, Aoba-ku, Sendai, Miyagi-prefecture 980-0856, Japan), organized by Japan Atomic Energy Agency (JAEA) and co-organized by the Reactor Physics Division of the Atomic Energy Society of Japan (AESJ) and the Nuclear Energy Agency of the Organization for Economic Co-operation and Development (OECD/NEA). 224 presentations passed peer review and 273 technical session registrations, bringing the total number of registered participants to 289, including accompanying persons. Technical tours were also conducted to i) Fukushima Daiichi Nuclear Power Station of TEPCO holdings and Interim Storage Facility Information Center, ii) Nuclear Science Research Institute of JAEA (STACY Renewable Reactor and FCA), iii) NanoTerasu of Tohoku University (synchrotron radiation facility) and Onagawa Nuclear Power Station of Tohoku Electric Power Co., Inc. This report summarizes the conference and compiles the papers that were presented and agreed to be published in the Proceedings.
00) MOS structures by means of electrical measurements and X-ray photoelectron spectroscopyKobayashi, Takuma*; Suzuki, Asato*; Nakanuma, Takato*; Sometani, Mitsuru*; Okamoto, Mitsuo*; Yoshigoe, Akitaka; Shimura, Takayoshi*; Watanabe, Heiji*
Materials Science in Semiconductor Processing, 175, p.108251_1 - 108251_7, 2024/06
Times Cited Count：4 Percentile：44.94(Engineering, Electrical & Electronic)Kato, Masato; Oki, Takumi; Watanabe, Masashi; Hirooka, Shun; Vauchy, R.; Ozawa, Takayuki; Uwaba, Tomoyuki; Ikusawa, Yoshihisa; Nakamura, Hiroki; Machida, Masahiko
Journal of the American Ceramic Society, 107(5), p.2998 - 3011, 2024/05
Times Cited Count：8 Percentile：47.05(Materials Science, Ceramics)Togawa, Orihiko; Okuno, Hiroshi
JAEA-Review 2023-043, 94 Pages, 2024/03
JAEA-Review-2023-043.pdf:1.53MB
In order to translate nuclear disaster prevention documents written in Japanese into English, the Basic Act on Disaster Management, the Act on Special Measures Concerning Nuclear Emergency Preparedness, and the Convention on Nuclear Safety were surveyed for corresponding terms in Japanese and English. The survey results were integrated and unified English translations were selected. As a result, a Japanese-English correspondence table of technical terms in the field of nuclear disaster prevention was prepared and proposed.
Fukahori, Tokio; Nakayama, Shinsuke; Katabuchi, Tatsuya*; Shigyo, Nobuhiro*
Nihon Genshiryoku Gakkai-Shi ATOMO
, 65(12), p.726 - 727, 2023/12
The Investigative Committee on Nuclear Data investigates and observes global trends in nuclear research and development and conducts comprehensive examinations of Japanese nuclear data activities from a broader perspective, as well as cooperation with domestic and foreign academic institutions in a wide range of fields other than the Atomic Energy Society. We aim to establish a system for communication, information exchange, and interdisciplinary cooperation. In this report, we will report on three of the main activities for the 2021-2022 term: a request list site for nuclear data, human resource development, and roadmap production.
Kawano, Takahiro*; Mizuta, Naoki; Ueta, Shohei; Tachibana, Yukio; Yoshida, Katsumi*
JAEA-Technology 2023-014, 37 Pages, 2023/08
JAEA-Technology-2023-014.pdf:2.35MB
Fuel compact for High Temperature Gas-cooled Reactor (HTGR) is fabricated by calcinating a matrix consisting of graphite and binder with the coated fuel particle. The SiC-matrixed fuel compact uses a new matrix made of silicon carbide (SiC) replacing the conventional graphite. Applying the SiC-matrixed fuel compact for HTGRs is expected to improve their performance such as power densities. In this study, the sintering conditions for applying SiC as the matrix of fuel compacts for HTGR are selected, and the density and thermal conductivity of the prototype SiC are measured.
Takayanagi, Tomohiro; Ono, Ayato; Horino, Koki*; Ueno, Tomoaki*; Sugita, Moe; Kinsho, Michikazu; Tokuchi, Akira*; Ikoma, Naoya*; Nakata, Kyosuke*; Kamezaki, Hiroaki*; et al.
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.235 - 239, 2023/08
The kicker system used for injection and extraction of accelerated beams requires a pulsed power supply with high speed and high repetition rate of short pulses acting only on a specified bunch of beams. We have developed a semiconductor switch power supply with a rated output of 40kV/2kA using SiC-MOSFETs, one of the next-generation power semiconductors. Then, we reconfigured this semiconductor switch power supply into two units with 20kV/2kA output and conducted energization tests using an actual kicker electromagnet. It was also demonstrated with magnetic field waveforms that the flat-top correction function of this power supply can suppress ringing in the waveform by less than half. This achievement enables the reduction of the kick angle difference caused by ringing, which is a factor in beam loss. In the presentation, specifications, test equipment, and evaluation results of the developed SiC semiconductor switch power supply will be reported.
Kawabori, Tatsuru*; Watanabe, Masashi; Imai, Yoshiyuki; Ueta, Shohei; Yan, X.; Mizoshiri, Mizue*
Applied Physics A, 129(7), p.498_1 - 498_9, 2023/07
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)We investigated a potential of femtosecond laser sintering of silicon carbide (SiC) using the nanoparticles in air. A SiC nanoparticle ink including polyvinylpyrrolidone and ethylene glycol exhibited intense absorption by SiC nanoparticles at the wavelength of 780 nm. The whole of the sintered film patterns from the surface to the bottom underwent significant oxidation at a scanning speed of 1 mm/s, suggesting that the excessive energy irradiation generated silicon oxides. In contrast, the patterns fabricated by laser scanning at a raster pitch of 30 
m at which a sintered area was observed at a scanning speed of 5 mm/s, exhibited no significant difference in oxidation of the raw SiC nanoparticles except for the surfaces from 1.72 m. These results indicate that the irradiation of femtosecond laser pulses generated the sintered SiC patterns without additional atmospheric oxidation of the raw materials because of its low heat accumulation. In additions, the dispersant of polyvinylpyrrolidone and ethylene glycol did not affect the sintering by an X-ray photoelectron spectroscopy. This vacuum-free direct printing technique has the potential for additive manufacturing.
Sakakibara, Ryotaro*; Bao, J.*; Yuhara, Keisuke*; Matsuda, Keita*; Terasawa, Tomoo; Kusunoki, Michiko*; Norimatsu, Wataru*
Applied Physics Letters, 123(3), p.031603_1 - 031603_4, 2023/07
Times Cited Count：9 Percentile：59.21(Physics, Applied)We here report a step unbunching phenomenon, which is the inverse of the phenomenon of step bunching. When a 4H-SiC (0001) surface is annealed at a high temperature, step bunching arises due to the different velocities of the step motion in adjacent steps, resulting in steps with a height of more than several nanometers. We found that the bunched steps, thus, obtained by hydrogen etching in an Ar/H atmosphere were "unbunched" into lower height steps when annealed subsequently at lower temperatures. This unbunching phenomenon can be well explained by the consequence of the competition between energetics and kinetics. Our findings provide another approach for the surface smoothing of SiC by hydrogen etching and may give significant insight into the application of SiC power devices and two-dimensional materials growth techniques in general.
Li, C.-Y.; Wang, K.*; Uchibori, Akihiro; Okano, Yasushi; Pellegrini, M.*; Erkan, N.*; Takata, Takashi*; Okamoto, Koji*
Applied Sciences (Internet), 13(13), p.7705_1 - 7705_29, 2023/07
Times Cited Count：2 Percentile：22.76(Chemistry, Multidisciplinary)Suzuki, Seiya; Arai, Yoichi; Okamura, Nobuo; Watanabe, Masayuki
Journal of Nuclear Science and Technology, 60(7), p.839 - 848, 2023/07
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)The fuel debris, consisting of nuclear fuel materials and reactor structural materials, generated in the accident of Fukushima Daiichi Nuclear Power Plant can become deteriorated like rocks under the changes of environmental temperature. Although the fuel debris have been cooled by water for 10 years, they are affected by seasonal and/or day-and-night temperature changes. Therefore, in evaluating the aging behavior of the fuel debris, it is essential to consider the changes in environmental temperature. Assuming that the fuel debris are deteriorated, radioactive substances that have recently undergone micronization could be eluted into the cooling water, and such condition may affect defueling methods. We focused on the effect of repeated changes in environmental temperature on the occurrence of cracks, and an accelerated test using simulated fuel debris was carried out. The length of the crack increases with increasing number of heat cycle; therefore, the fuel debris become brittle by stress caused by thermal expansion and contraction. In conclusion, it was confirmed that the mechanical deterioration of the fuel debris is similar to that of rocks or minerals, and it became possible to predict changes in the length of the crack in the simulated fuel debris and environmental model.
