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Journal Articles

Simulation of a jet flow rectified by a grating-type structure using immersed boundary methods

Hirose, Yoshiyasu; Abe, Satoshi; Ishigaki, Masahiro*; Shibamoto, Yasuteru; Hibiki, Takashi*

Progress in Nuclear Energy, 169, p.105085_1 - 105085_13, 2024/04

Journal Articles

Application of analytical wall functions to CFD analysis of condensation flow

Soma, Shu; Ishigaki, Masahiro*; Abe, Satoshi; Shibamoto, Yasuteru

Nuclear Engineering and Design, 416, p.112754_1 - 112754_18, 2024/01

Journal Articles

The Role of collision ionization of K-shell ions in nonequilibrium plasmas produced by the action of super strong, ultrashort PW-class laser pulses on micron-scale argon clusters with intensity up to 5 $$times$$ 10$$^{21}$$ W/cm$$^{2}$$

Skobelev, I. Yu.*; Ryazantsev, S. N.*; Kulikov, R. K.*; Sedov, M. V.*; Filippov, E. D.*; Pikuz, S. A.*; Asai, Takafumi*; Kanasaki, Masato*; Yamauchi, Tomoya*; Jinno, Satoshi; et al.

Photonics (Internet), 10(11), p.1250_1 - 1250_11, 2023/11

It is challenging to clearly distinguish the impacts of the optical field and collisional ionization in the evolution of the charge state of a plasma produced when matter interacts with high-intensity laser pulses. In this work, time-dependent calculations of plasma kinetics are used to show that it is possible only when low-density gaseous targets with sufficiently small clusters are used. In the case of Ar plasma, the upper limit of the cluster radius was estimated to be $$R_0 = 0.1 mu$$m.

Journal Articles

Study on criticality safety control of fuel debris for validation of methodology applied to the safety regulation

Suyama, Kenya; Ueki, Taro; Gunji, Satoshi; Watanabe, Tomoaki; Araki, Shohei; Fukuda, Kodai; Yamane, Yuichi; Izawa, Kazuhiko; Nagaya, Yasunobu; Kikuchi, Takeo; et al.

Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 6 Pages, 2023/10

To remove and store safely the fuel debris generated by the severe accident of the Fukushima Daiichi Nuclear Power Station in 2011 is one of the most important and challenging topics for decommissioning of the damaged reactors in Fukushima. To validate the adopted method for the evaluation of criticality safety control of the fuel debris through comparison with the experimental data obtained by the criticality experiments, the Nuclear Regulation Authority (NRA) of Japan funds a research and development project which was entrusted to the Nuclear Safety Research Center (NSRC) of Japan Atomic Energy Agency (JAEA) from 2014. In this project, JAEA has been conducting such activities as i) comprehensive computation of the criticality characteristics of the fuel debris and making database (criticality map of the fuel debris), ii) development of new continuous energy Monte Carlo code, iii) evaluation of criticality accident and iv) modification of the critical assembly STACY for the experiments for validation of criticality safety control methodology. After the last ICNC2019, the project has the substantial progress in the modification of STACY which will start officially operation from May 2024 and the development of the Monte Carlo Code "Solomon" suitable for the criticality calculation for materials having spatially random distribution complies with the power spectrum. We present the whole picture of this research and development project and status of each technical topics in the session.

Journal Articles

Inter-codes and nuclear data comparison under collaboration works between IRSN and JAEA

Gunji, Satoshi; Araki, Shohei; Watanabe, Tomoaki; Fernex, F.*; Leclaire, N.*; Bardelay, A.*; Suyama, Kenya

Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 9 Pages, 2023/10

Institut de radioprotection et de s$^{u}$ret$'{e}$ nucl$'{e}$aire (IRSN) and Japan Atomic Energy Agency (JAEA) have a long-standing partnership in the field of criticality safety. In this collaboration, IRSN and JAEA are planning a joint experiment using the new STACY critical assembly, modified by JAEA. In order to compare the codes (MVP3, MORET6, etc.) and nuclear data (JENDL and JEFF) used by both institutes in the planning of the STACY experiment, benchmark calculations of the Apparatus B and TCA, which are critical assemblies once owned by both institutes, benchmarks from the ICSBEP handbook and the computational model of the new STACY were performed. Including the new STACY calculation model, the calculations include several different neutron moderation conditions and critical water heights. There were slight systematic differences in the calculation results, which may have originated from the processing and/or format of the nuclear data libraries. However, it was found that the calculated results, including the new codes and the new nuclear data, are in good agreement with the experimental values. Therefore, there are no issues to use them for the design of experiments for the new STACY. Furthermore, the impact of the new TSL data included in JENDL-5 on the effective multiplication factor was investigated. Experimental validation for them will be completed by critical experiments of the new STACY by both institutes.

Journal Articles

Key role of temperature on delamination in solid-state additive manufacturing via supersonic impact

Wang, Q.*; Ma, N.*; Huang, W.*; Shi, J.*; Luo, X.-T.*; Tomitaka, Sora*; Morooka, Satoshi; Watanabe, Makoto*

Materials Research Letters (Internet), 11(9), p.742 - 748, 2023/09

Journal Articles

Consideration of creep relaxation initial stress setting method used to inelastic analysis for fast reactor components design

Noi, Hiromi*; Watanabe, Sota*; Kubo, Koji*; Okajima, Satoshi; Ando, Masanori

Nihon Kikai Gakkai M&M 2023 Zairyo Rikigaku Kanfarensu Koen Rombunshu (Internet), p.CL0712_1 - CL0712_5, 2023/09

no abstracts in English

Journal Articles

Numerical simulation of bubble hydrodynamics for pool scrubbing

Okagaki, Yuria; Shibamoto, Yasuteru; Wada, Yuki; Abe, Satoshi; Hibiki, Takashi*

Journal of Nuclear Science and Technology, 60(8), p.955 - 968, 2023/08

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

Journal Articles

Local electronic structure of interstitial hydrogen in MgH$$_2$$ inferred from muon study

Kadono, Ryosuke*; Hiraishi, Masatoshi*; Okabe, Hirotaka*; Koda, Akihiro*; Ito, Takashi

Journal of Physics; Condensed Matter, 35(28), p.285503_1 - 285503_13, 2023/07

Journal Articles

Cavitation damage prediction in mercury target for pulsed spallation neutron sources by Monte Carlo simulation

Wakui, Takashi; Takagishi, Yoichi*; Futakawa, Masatoshi; Tanabe, Makoto*

Jikken Rikigaku, 23(2), p.168 - 174, 2023/06

Cavitation damage on the inner surface of the mercury target for the spallation neutron source occurs by proton bombarding in mercury. The prediction method of the cavitation damage using Monte Carlo simulations was suggested taking variability of the bubble core position and impact pressure distribution into account. The impact pressure distribution was estimated using the inverse analysis with Bayesian optimization was conducted with comparison between cavitation damage distribution obtained from experiment and the cumulative plastic strain distribution obtained from simulation. The average value and spread of maximum impact pressure estimated assuming the Gaussian distribution were 3.1 GPa and 1.2 $$mu$$m, respectively. Simulation results reproduced experimental results and it can be said that this evaluation method is useful.

Journal Articles

Revision of the criticality safety handbook in light of the reality of the nuclear fuel cycle in Japan; With a view to transportation and storage of fuel debris

Suyama, Kenya; Ueki, Taro; Gunji, Satoshi; Watanabe, Tomoaki; Araki, Shohei; Fukuda, Kodai

Proceedings of 20th International Symposium on the Packaging and Transportation of Radioactive Materials (PATRAM22) (Internet), 5 Pages, 2023/06

Since the 1990s, the importance of the handbook has changed significantly, as the computational power has improved and continuous energy Monte Carlo codes have become widely used, which enables highly accurate criticality calculations, when necessary, irrespective of the complexity of the system. Because the value of performing a large number of calculations in advance and summarizing the data has decreased, since the second edition was published publicly in 1999, there has been no revision of criticality safety handbooks in Japan for nearly a quarter of a century. In Japan, where the Fukushima Daiichi Nuclear Power Plant accident occurred in 2011, it became necessary to deal with criticality safety issues in the transport and storage of the fuel debris which contains complex constituent elements, and the summary the criticality safety management for such material is an urgent issue. In the area of burnup credit, the transport and storage of fuel assemblies with low achieved burnups due to the consequences of accidents might be the problem. In addition, nuclear data, which is the input for the continuous energy Monte Carlo code, has been improved several times, now JENDL-5 is available from the end of 2021, and its incorporation becomes a need in the field. This report provides an overview of the latest criticality safety research in Japan and the planned revision of the Criticality Safety Handbook, which could be applied to the transport and storage sectors.

Journal Articles

Large-eddy simulation on gas mixing induced by the high-buoyancy flow in the CIGMA facility

Abe, Satoshi; Shibamoto, Yasuteru

Nuclear Engineering and Technology, 55(5), p.1742 - 1756, 2023/05

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

Journal Articles

Seismic evaluation of crossover piping on a sodium cooled fast reactor with three-dimensional isolation system

Watakabe, Tomoyoshi; Okuda, Takahiro; Okajima, Satoshi

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 5 Pages, 2023/05

A three-dimensional seismic isolation system is planed for application to the conceptual design of a sodium-cooled fast reactor (SFR) in Japan. The crossover piping is laid between the nuclear building with the isolation system and the turbine building without the isolation system. A large displacement of the nuclear building with the isolation system is imposed on the crossover piping, which situation is a particular seismic issue because of the isolation system employment. Furthermore, it should be considered that the SFR operates at elevated temperatures compared with light water reactors. In this study, seismic evaluation using an example of a crossover piping layout was performed in accordance with the elevated temperature code of Japan Society of Mechanical Engineers. According to the evaluation results and the up to date technologies such as knowledge obtained from existing dynamic failure tests of piping components, an appropriate seismic evaluation method for the crossover piping was studied.

Journal Articles

Nature of the physicochemical process in water photolysis uncovered by a computer simulation

Kai, Takeshi; Toigawa, Tomohiro; Ukai, Masatoshi*; Fujii, Kentaro*; Watanabe, Ritsuko*; Yokoya, Akinari*

Journal of Chemical Physics, 158(16), p.164103_1 - 164103_8, 2023/04

New insight into water radiolysis and photolysis is indispensable in the dramatic progress of sciences and technologies in various research areas. In the radiation field, reactive hydrated electrons are considerably produced along radiation tracks. Although the formation results from a transient dynamic correlation between ejected electrons and water, the individual mechanisms of electron thermalization, delocalization, and polarization are unknown. Using a dynamic Monte Carlo code, we show herein that the ejected electrons are immediately delocalized by molecular excitations in parallel with phonon polarization and gradually thermalized by momentum transfer with an orientation polarization in a simultaneous manner. Our results show that these mechanisms heavily depend on the intermolecular vibration and rotation modes peculiar to water. We expect our approach to be a powerful technique for connecting physical and chemical processes in various solvents.

Journal Articles

Large-eddy simulation on two-liquid mixing in the horizontal leg and downcomer (the TAMU-CFD Benchmark), with respect to fluctuation behavior of liquid concentration

Abe, Satoshi; Okagaki, Yuria

Nuclear Engineering and Design, 404, p.112165_1 - 112165_14, 2023/04

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

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2021

Nakada, Akira; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Futagawa, Kazuo; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; et al.

JAEA-Review 2022-078, 164 Pages, 2023/03


Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2021 to March 2022. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.

Journal Articles

Present status of the JAEA-AMS-TONO (2021)

Matsubara, Akihiro*; Fujita, Natsuko; Miyake, Masayasu; Ishii, Masahiro*; Watanabe, Takahiro; Kokubu, Yoko; Nishio, Tomohiro*; Ogawa, Yumi; Jinno, Satoshi; Kimura, Kenji; et al.

JAEA-Conf 2022-002, p.55 - 62, 2023/03

We report the present status of the JAEA-AMS-TONO. Particularly, the destructions of varistors used in the beamline equipment will be presented. The cause of the destruction as well as implementation of the safety measures are mentioned.

Journal Articles

Fact-finding survey on the competencies and literacy of radiological technologists regarding radiation disasters

Arai, Tomohiro*; Murata, Sho*; Watanabe, Yuichi*; Ishihara, Toshihiro*; Fukamizu, Yoshiya*; Takeda, Satoshi*; Ebata, Kiyokadzu*; Watanabe, Yuki; Takashima, Yoshio*; Kaneko, Junichi*

Journal of X-Ray Science and Technology, 31(2), p.237 - 245, 2023/03

 Times Cited Count:0 Percentile:0(Instruments & Instrumentation)

Radiological technologists have received specialized education about radiation and serve as risk communicators who aim to lessen patients' anxiety about radiation exposure, in addition to performing radiological examinations in routine clinical practice. Also, Radiological technologists across Japan were dispatched to the affected area to conduct an essential procedure-screening the belongings and body surfaces of evacuees for contamination at the nuclear disaster at the Fukushima Daiichi Nuclear Power Plant operated by Tokyo Electric Power Company in March 2011. In this study, we conducted a fact-finding survey on knowledge and awareness of radiation disasters among radiological technologists at National Hospital Organization facilities in Japan to reveal their literacy and competencies regarding radiation disasters. Also, we compared the knowledge and awareness of radiation disasters among Japanese radiological technologists between nuclear power station areas and non-nuclear power station areas and discuss ideal human resource development for radiological technologists to be ready to serve during a radiation disaster.

Journal Articles

Japanese Evaluated Nuclear Data Library version 5; JENDL-5

Iwamoto, Osamu; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Nakayama, Shinsuke; Abe, Yutaka*; Tsubakihara, Kosuke*; Okumura, Shin*; Ishizuka, Chikako*; Yoshida, Tadashi*; et al.

Journal of Nuclear Science and Technology, 60(1), p.1 - 60, 2023/01

 Times Cited Count:17 Percentile:99.99(Nuclear Science & Technology)

Journal Articles

Present status of the JAEA-AMS-TONO (2022FY)

Fujita, Natsuko; Miyake, Masayasu; Matsubara, Akihiro*; Ishii, Masahiro*; Watanabe, Takahiro; Jinno, Satoshi; Nishio, Tomohiro*; Ogawa, Yumi; Yamamoto, Yusuke; Kimura, Kenji; et al.

Dai-23-Kai AMS Shimpojiumu Hokokushu, p.1 - 4, 2022/12

The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has three accelerator mass spectrometers. We report the present status of the JAEA-AMS-TONO.

769 (Records 1-20 displayed on this page)