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Yamakawa, Koki*; Hiramatsu, Masako*; Moritani, Hiroshi*; Iiba, Masanori*; Nishida, Akemi; Shiomi, Tadahiko; Choi, B.; Iigaki, Kazuhiko
Transactions of the 28th International Conference on Structural Mechanics in Reactor Technology (SMiRT28) (Internet), 9 Pages, 2025/08
To understand the three-dimensional seismic behavior of nuclear buildings, the Nuclear Regulation Authority (NRA) and the Japan Atomic Energy Agency (JAEA) have been conducting research and development aimed at improving the accuracy of three-dimensional seismic analysis methods for nuclear buildings. A large-scale observation system was constructed in the High Temperature engineering Test Reactor (HTTR) building of JAEA, enabling seismic observation and artificial wave excitation. Using this system, vibration characteristics of the HTTR building have been analyzed based on both seismic observation records and analyses using a three-dimensional seismic analysis model of the HTTR building. This paper reports on the vibration characteristics of the HTTR building obtained from the analysis of seismic observation records, as well as on the improvements made to the three-dimensional finite element model and the results of simulation analyses using artificial waves. In particular, this paper presents the results of an analysis of the Fourier spectral ratio at the first floor of the HTTR building based on seismic records, and discusses the dominant frequencies and acceleration modes of the superstructure.
Yamakawa, Koki*; Moritani, Hiroshi*; Saruta, Masaaki*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 10 Pages, 2024/03
no abstracts in English
Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 6 Pages, 2021/08
Several large-scale earthquakes have occurred, such as the Niigataken Chuetsu-oki Earthquake in 2007 and the 2011 off-the-Pacific coast of Tohoku Earthquake. Therefore, a three-dimensional (3D) finite element model to evaluate the local response of the reactor building is currently being developed for seismic response analysis. In order to refine the 3D finite element model, it is important to verify the correspondence to the seismic observation behaviors. In this study, the authors analyze the basic response characteristics, such as the natural frequencies and modes of the reactor building, and evaluate the effects of the amplitude of the seismic excitation on the response characteristics based on seismic observation records. This is done to clarify the behavior of a reactor building during earthquakes. These analyses will assist in quantitatively evaluating the correlation between the natural frequency of the building and the amplitude of the seismic excitation. Furthermore, the ratios of rotational displacement and displacement caused by building deformation for natural modes are discussed.
Ichihara, Yoshitaka*; Nakamura, Naohiro*; Moritani, Hiroshi*; Choi, B.; Nishida, Akemi
Frontiers in Built Environment (Internet), 7, p.676408_1 - 676408_14, 2021/06
The objective of this study is the improvement of response evaluations of structures, facilities and equipment in evaluation of three-dimensional seismic behavior of nuclear power plant facilities, by three-dimensional finite element method model, including separation and sliding between the soil and the basement walls. To achieve this, simulation analyses of Kashiwazaki Kariwa nuclear power plant unit 7 reactor building under the 2007 Niigataken-chuetsu-oki earthquake event were carried out. These simulation analyses consider soil-structure interaction using a three-dimensional finite element method model in which the soil and building are three-dimensionally modeled by the finite element method. It is found that basemat uplift is generated on east side of the basemat edge, and this has an important influence on the results. The importance is evidenced by the difference of local response in soil pressure characteristics beneath the edge of basemat, the soil pressure characteristics along the east side of basement wall and the maximum acceleration response at the west end of the embedded surface. Although, in this particular study, basemat uplift, separation and sliding have only a relatively small influence on the maximum acceleration response of embedded surface and the soil pressure characteristics along the basement walls and beneath the basemat, under strong earthquake motion, these influences can be significant, therefore appropriate evaluation of this effect should be considered.
Nishida, Satoru*; Nishino, Soichiro*; Sekine, Masahiko*; Oka, Yuki*; Harjo, S.; Kawasaki, Takuro; Suzuki, Hiroshi; Morii, Yukio*; Ishii, Yoshinobu*
Materials Transactions, 62(5), p.667 - 674, 2021/05
Times Cited Count：8 Percentile：31.24(Materials Science, Multidisciplinary)Nishida, Akemi; Suzuki, Yoshio; Yamada, Tomonori; Kino, Chiaki; Uzawa, Ken*; Miyamura, Hiroko; Kawamura, Takuma; Takemiya, Hiroshi; Nakajima, Norihiro
RIST News, (54), p.33 - 37, 2013/01
Nuclear plants are complicated and huge structures and consist of a large number of parts. To simulate the behavior of such a complicated huge structure, it becomes important the viewpoint as a general system including pre-post-processing. Therefore, the CCSE proposed an approach for assembly structure analysis and implemented a framework of a full-scale 3D vibration simulator for an entire nuclear plant. Until now, we performed numerical experiments using the data of a building and equipment of HTTR, Oarai R&D Center, JAEA, and demonstrated that earthquake response simulation of large-scale structure as an entire nuclear plant was possible so far. In this report, the framework of the full-scale 3D vibration simulator, the assembly structure analysis approach and visualization technology for an evaluation of the results are shown. And finally, an example of application of the simulator for probabilistic risk assessment, PRA, started from 2011, is shown.
Kino, Chiaki; Watanabe, Tadashi*; Nishida, Akemi; Takemiya, Hiroshi
Nihon Kikai Gakkai Rombunshu, B, 78(796), p.2113 - 2126, 2012/12
Flow around an in-line forced oscillating circular cylinder was simulated numerically by using OpenFOAM in order to clarify the mechanism of flow induced vibration. Immersed boundary Method is used to solve the moving boundary. Reynolds number is set to 1000 and the reduced velocity is set to the range from 0 to 10. In the first excitation region, it is shown that negative drag force which is a factor for an in-line oscillation of a circular cylinder comes from contacting between high pressure region and a circular cylinder. The present simulation shows that twin vortex has an important role on the contact phenomena. In the second excitation region, it is shown that time averaged lift drag doesn't become zero on some oscillating conditions. It is considered that a cross-flow oscillation comes from the phenomena.
Uzawa, Ken; Watanabe, Tadashi; Nishida, Akemi; Suzuki, Yoshio; Takemiya, Hiroshi
High Performance Computing on Vector Systems 2011, p.171 - 184, 2012/01
The Center for Computational Science and E-systems (CCSE) has been promoting researches and developments for the full-scale 3D vibration simulator of an entire nuclear power plant, which is a virtual plant vibration simulator on inter-connected supercomputers. Application example of the vibration simulator to High Temperature Engineering Test Reactor (HTTR) and recent progress of collaborative work for JST-CREST program "Multiscale and multiphysics earthquake-proof simulation" are shown. This year, we started to implement the analysis capability of fluid effects to the vibration simulator. We have presented a two-phase flow model for analyzing a sloshing and suggested importance of turbulent effect to estimate the flow impact on the structure more precisely.
Kino, Chiaki; Tatekawa, Takayuki; Teshima, Naoya; Kim, G.; Suzuki, Yoshio; Araya, Fumimasa; Nishida, Akemi; Takemiya, Hiroshi
Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10
In the present study, we have developed a new control system for application integration with the fault-tolerant API (FT-API). The system treats an application as a task which consists of one job and multiple file transfer. Firstly, each task designates a computer to submit a job using a scheduler associated to the job. Secondly, all files which are necessary to execute the job are gathered in the computer using FT-API for file transfer. Finally, the job is submitted using FT-API for job execution. If the computer is outage, the task designates a new computer, gathers necessary files and submits a new job. Each scheduler, file transfer and job condition can be flexibly defined in XML. This time, we applied the system to fluid-structure interaction analysis simulation. The result indicates that the system enables a user to easily execute multi-scale and multi-physics simulation using application integration.
Nakajima, Norihiro; Nishida, Akemi; Suzuki, Yoshio; Yamada, Tomonori; Takemiya, Hiroshi; Iyoku, Tatsuo
Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10
FIESTA is a large scale simulation, which concerns a simulation space to bring real world in digital space, such as so named either virtual reality or virtual facility. In order to establish a huge and complex object like nuclear facilities of a real world, there are lack of methodology and technology for reproducing facilities in digital space. FIESTA attempts to realize an assembly structural analysis for supplying one of the methodologies to reproduce facilities in digital space. The first attempt of the structural analysis for assembly is accomplished by finite element analysis by integrating parts of facilities. Since the structural analysis for assembly requests massive calculation, parallel and distributed computing was applied for the computational environment. The structural analysis for assembly by finite element method is confirmed to be able to analyze a huge and complex facility and show results of numerical experiment by applying to a test reactor driven by JAEA.
Uzawa, Ken; Watanabe, Tadashi; Nishida, Akemi; Takemiya, Hiroshi
Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 6 Pages, 2010/10
When big response acceleration is added to air-liquid two-phase flow in nuclear reactor plant, large deformation of the interface configuration with breakup/coalescence of bubbles and micro-scale turbulence near the interface may change heat transfer and void fraction distribution in the reactor core. Now we have been developed a numerical tool for detailed analysis of the two-phase flow based on OpenFOAM which is an open source computational fluid dynamics software package to sophisticate "Three-Dimensional Virtual Plant Vibration Simulator". In this report, we show the validity of OpenFOAM by comparing results obtained by OpenFOAM with those obtained by experimental results. Findings for turbulent effects near the interface on dynamics of the two-phase flow are also reported.
diffusion in cubic 
-electron compounds observed by high transverse field SRIto, Takashi; Higemoto, Wataru; Oishi, Kazuki*; Nishida, Nobuhiko*; Heffner, R. H.; Aoki, Yuji*; Suzuki, Hiroyuki*; Onimaru, Takahiro*; Tanida, Hiroshi*; Takagi, Shigeru*
Journal of Physics; Conference Series, 225, p.012021_1 - 012021_6, 2010/06
Times Cited Count：2 Percentile：65.08(Physics, Applied)The diffusion of positive muon in condensed matter has been investigated for many years by using spin rotation/relaxation (SR) technique. The SR studies have provided deep insight into quantum diffusion at low temperatures as well as hopping process at high temperatures, which are closely related to hydrogen dynamics in the dilute limit. We here report transverse field (TF) SR studies of the diffusion in cubic -electron compounds PrPb
and SmAg
In. The site splits into two magnetically labeled sites when high TF is applied to single-crystalline specimens along the [001] direction. The SR lines show drastic variation according to the motion between the magnetically labeled sites. From detailed analysis of the SR lines, we deduced hopping parameters for both compounds.
Kim, G.; Suzuki, Yoshio; Teshima, Naoya; Nishida, Akemi; Yamada, Tomonori; Araya, Fumimasa; Takemiya, Hiroshi; Nakajima, Norihiro; Kondo, Makoto
Proceedings of 1st International Conference on Parallel, Distributed and Grid Computing for Engineering (PARENG 2009) (CD-ROM), 12 Pages, 2009/04
Nishida, Akemi; Araya, Fumimasa; Yamada, Tomonori; Kushida, Noriyuki; Takemiya, Hiroshi; Nakajima, Norihiro
Anzen Kenkyu Fuoramu 2009 Shiryoshu, p.25 - 29, 2009/02
The development of a vibration simulator has been planned for used in a full-scale nuclear power station; this simulator will implement the latest computational technologies and will allow comparisons to be made among the conventional spring-mass models and the actually observed data obtained from experiment and practice. This simulator will be used for evaluating the conservativeness of conventional models and the fragility of components through a seismic PSA (probabilistic safety assessment). This simulator will be used for analyzing the seismic responses of the entire nuclear facility by modeling each component independently. The numerical capability of the simulator has already been confirmed; presently, the accuracy of the dynamic response results is being investigated by means of a comparison with the recorded data of an actual plant system.
Nakajima, Norihiro; Araya, Fumimasa; Nishida, Akemi; Suzuki, Yoshio; Ida, Masato; Yamada, Tomonori; Kushida, Noriyuki; Kim, G.; Kino, Chiaki; Takemiya, Hiroshi
Proceedings of International Symposium on Structures under Earthquake, Impact, and Blast Loading 2008, p.119 - 123, 2008/10
Japan is so said an energy consumption country of the fourth place world, but the energy resources such as petroleum, the natural gas are poor and depend on import for the most, and stable supply becomes a big problem. For the greenhouse gas restraint, the promotion of the energy saving is featured. A nuclear power plant for commerce in Japan has been started in 1966. The supply occupies about 30 percent of the now Japanese electricity generating. Due to the nature of Japan, earthquake proof is an important subject for social infrastructure operation. To encourage its proofing, many approaches have been applied into many infrastructures, not only computational approach. A computational science approach for earthquake proof is suggested with FIESTA(Finite Element Structural analysis for Assembly), a large scale simulation. A methodology is discussed from the point of view of impact and blast loadings. Examples of loadings in the nuclear engineering are introduced.
Bakhtiari, M.; Tamai, Hiroshi; Kawano, Yasunori; Kramer, G. J.*; Isayama, Akihiko; Nakano, Tomohide; Kamiya, Kensaku; Yoshino, Ryuji; Miura, Yukitoshi; Kusama, Yoshinori; et al.
Nuclear Fusion, 45(5), p.318 - 325, 2005/05
Times Cited Count：50 Percentile：80.07(Physics, Fluids & Plasmas)In the previous works we had shown that injecting a mixture of large amounts of hydrogen and small amounts of argon can terminate a tokamak discharge quickly with avoiding runaway electron generation. In this work we have done the same experiments but with different gases in addition to argon. In fact we compared the effect of the puffing of argon, krypton, and xenon gases with and without simultaneous hydrogen gas puffing on disruption mitigation. We observed that injecting all impurities in the form of an admixture in hydrogen lead to faster plasma shutdowns with less runaway electron generation. We also found that injecting krypton gas (with or without hydrogen) seems to be a good candidate for plasma shutdown purposes since it induces low heat flux to divertor plates and avoids runaway electron generation more effectively.
Bakhtiari, M.; Kawano, Yasunori; Tamai, Hiroshi; Miura, Yushi; Yoshino, Ryuji; Nishida, Yasushi*
Nuclear Fusion, 42(10), p.1197 - 1204, 2002/10
Times Cited Count：52 Percentile：80.54(Physics, Fluids & Plasmas)no abstracts in English
Ogata, Atsushi*; Okamoto, Hiromi*; Kusano, Kanya*; Endo, Ichita*; Nishida, Yasushi*; Sakae, Takeji*; Arai, Masatoshi*; Nakanishi, Hiroshi*; Kondo, Kiminori*
JAERI-Tech 2002-007, 28 Pages, 2002/03
JAERI-Tech-2002-007.pdf:1.34MB
no abstracts in English
Kato, Takashi; Hamada, Kazuya; Kawano, Katsumi; Matsui, Kunihiro; Hiyama, Tadao; Nishida, Kazuhiko*; Honda, Tadaaki*; Taneda, Masanobu*; Sekiguchi, Shuichi*; Otsu, Kiichi*; et al.
ICEC16/ICMC Proceedings, p.127 - 130, 1996/00
no abstracts in English
Shin, Sumio*; Sato, Kiichi*; Nishida, Hiroshi*; Sakamoto, Shoichi*; Yamabayashi, Hisamichi; Motoki, Ryozo; Terunuma, Kusuo; Yamamoto, Takeo
Igaku No Ayumi, 140(1), p.51 - 52, 1987/01
Trace elements serve as key components of enzyme systems and have especially important correlation with fetal maturity.
