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Journal Articles

Estimation of vibration characteristics of nuclear facilities based on seismic observation records

Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko

Proceedings of 28th International Conference on Nuclear Engineering; Nuclear Energy the Future Zero Carbon Power (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.

Journal Articles

Visualization in response analyses for a nuclear power plant

Nakajima, Norihiro; Nishida, Akemi; Miyamura, Hiroko; Iigaki, Kazuhiko; Sawa, Kazuhiro

Kashika Joho Gakkai-Shi (USB Flash Drive), 36(Suppl.2), 4 Pages, 2016/10

Since nuclear power plants have dimensions approximately 100m$$^{3}$$ and their structures are an assembly made up of over 10 million components, it is not convenient to experimentally analyze its behavior under strong loads of earthquakes, due to the complexity and hugeness of plants. The proposed system performs numerical simulations to evaluate the behaviors of an assembly like a nuclear facility. The paper discusses how to carry out visual analysis for assembly such as nuclear power plants. In a result discussion, a numerical experiment was carried out with a numerical model of High Temperature engineering Test Reactor of Japan Atomic Energy Agency and its result was compared with observed data. A good corresponding among them was obtained as a structural analysis of an assembly by using visualization. As a conclusion, a visual analytics methodology for assembly is discussed.

Journal Articles

Influence of differences between seismic safety evaluation methods for equipment and piping of a nuclear facility

Nishida, Akemi; Iigaki, Kazuhiko; Sawa, Kazuhiro; Li, Y.

Proceedings of 2015 ASME Pressure Vessels and Piping Conference (PVP 2015) (Internet), 7 Pages, 2015/07

The objective of this research was to investigate the influence of differences between methods for evaluating the seismic safety of the equipment and piping of a nuclear facility. For the input ground motion, one wave was chosen from among 200 waves of input ground motions of maximum acceleration of 700-1100 cm/s$$^{2}$$ created for the Oarai District of the Ibaraki Prefecture. Seismic safety evaluations were performed using the conventional method, which relies on floor response spectrum data, and using the multi-input method. The differences between the two methods were summarized. The target equipment and piping system were cooling systems in a model plant. It was found that the response predicted by the multi-input method was approximately half of the response predicted by the conventional method. The third trial evaluation method using the floor response of a three-dimensional building model as input was also reported.

Journal Articles

Seismic response simulation of High-Temperature Engineering Test Reactor building against 2011 Tohoku earthquake

Nishida, Akemi; Nakajima, Norihiro; Kawakami, Yoshiaki; Iigaki, Kazuhiko; Sawa, Kazuhiro

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05

The R&D on the three dimensional vibration simulation technologies for a nuclear facility is one of missions of Center for Computational Science and e-Systems, Japan Atomic Energy Agency. Until now, three dimensional building and equipment models of HTTR (High Temperature Engineering Test Reactor) have been constructed and been performed validation of the models by comparison with seismic observed records. In this report, the results obtained by seismic observation simulation on the Tohoku earthquake occurred in the 3/11/2011 using three dimensional models of the HTTR building are shown. The simulation results show good agreement with the real observation data.

Journal Articles

Numerical modeling assistance system in finite element analysis for the structure of an assembly

Nakajima, Norihiro; Nishida, Akemi; Kawakami, Yoshiaki; Suzuki, Yoshio; Sawa, Kazuhiro; Iigaki, Kazuhiko

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05

A numerical analysis controlling and managing system is implemented on K, which controls the modelling process and data treating, although the manager only controls a structural analysis by finite element method. The modeling process is described by the list of function ID and its procedures in a data base. The manager executes the process by order in the list for simulation procedures. The manager controls the intention of an analysis by changing the analytical process one to another. Experiments were carried out with static and dynamic analyses.

Journal Articles

Structural analysis for assembly by integrating parts

Nakajima, Norihiro; Nishida, Akemi; Kawakami, Yoshiaki; Okada, Tatsuo*; Tsuruta, Osamu*; Sawa, Kazuhiro; Iigaki, Kazuhiko

Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 9 Pages, 2014/07

Almost all industrial products are assembled from multiple parts. A nuclear facility is a large structure consisting of more than 10 million components. This paper discusses a method to analyze an assembly by gathering data on its component parts. Gathered data on component may identify ill conditioned meshes for connecting surfaces between components. These ill meshes are typified by nodal point disagreement in finite element discretization. A technique to resolve inconsistencies in data among the components is developed. By using this technique, structural analysis for an assembly can be carried out, and results can be obtained by the use of supercomputers, such as the K computer. Numerical results are discussed for components of the High Temperature Engineering Test Reactor.

Journal Articles

A Quake-proof analysis for a plant as an assembly in the next generation

Nakajima, Norihiro; Nishida, Akemi; Kawakami, Yoshiaki; Okada, Tatsuo; Tsuruta, Osamu; Sawa, Kazuhiro; Iigaki, Kazuhiko

Tabo Kikai, 42(5), p.332 - 338, 2014/05

K computer is one of the highest performance computers in the world. This paper discusses one of R&D issues in K computer national project. Industrial products are an artifact, which are assembly consisting of simple components more than at least two regardless of the big products and small products. In the nuclear industry, the facilities are large structures consisting of over 10 millions of components, since they are engaged with the highest technology and for safety sake. This paper introduces a method to analyze an assembly by gathering its components data. In the manner of gathering components data, it is raised many issues to concern among components. It is developed a technique to solve the inconsistent data among the components. By using this technique, a structural analysis for an assembly is done by using K computer. Numerical results are presented in the case of analysis for High Temperature engineering Test Reactor's components.

Journal Articles

Assembly structure analysis system

Nakajima, Norihiro; Nishida, Akemi; Matsubara, Hitoshi*; Hazama, Osamu*; Suzuki, Yoshio; Sawa, Kazuhiro; Iigaki, Kazuhiko

Transactions of 22nd International Conference on Structural Mechanics in Reactor Technology (SMiRT-22) (CD-ROM), 10 Pages, 2013/08

It is not convenient to experimentally analyze its behavior under strong loads of earthquakes, since the facility is extremely huge and complex. The proposed system performs numerical simulations to evaluate the behaviors of an assembly like a nuclear facility. This system projects the components of an assembly onto both/either a distributed and/or a parallel computing environment in order to conduct a simulation of the behavior of an assembly such as a nuclear facility. In a result discussion, a numerical experiment was carried out with a cantilever model and its result was compared with theoretical data. A good corresponding among them was obtained as a structural analysis of an assembly by using a parallel computer. As a conclusion, a suggested methodology has shown to calculate a behavior of an assembly with High Temperature engineering Test Reactor.

Journal Articles

Impact response analysis of a coaxial double-pipe structure by using spectral element method

Nishida, Akemi; Iigaki, Kazuhiko

Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 9 Pages, 2011/07

A coaxial double-pipe structure is to be used in the primary and auxiliary coolant system of a high-temperature gas-cooled reactor. In order to study the vibration characteristics of the coaxial double-pipe structure, hammering experiments were performed using specimens of the structure. Because the structural responses obtained in the experiments contained high-frequency components, impact response analysis was performed by using the spectral element method, which has high accuracy in the high-frequency region. A comparison between analysis results and experiment results showed good agreement between them. We also performed parametric studies on the damping properties of the specimens. The damping properties determined from the experiment results indicated that the inner and outer pipes had different damping properties.

Journal Articles

Impact response analysis of a coaxial double-pipe structure

Nishida, Akemi; Iigaki, Kazuhiko

Dai-59-Kai Riron Oyo Rikigaku Koenkai Koen Rombunshu (CD-ROM), 2 Pages, 2010/06

A coaxial double-pipe structure is to be used in the main primary coolant system of a high-temperature gas-cooled reactor. In order to study the vibration characteristics of a coaxial double-pipe structure, hammering tests were performed on test models of a coaxial double-pipe structure. Because the input forces and structural responses included high frequency components in this type of tests, impact response analysis was performed by using spectral element that has high precision in the high frequency domain. By the comparison between analysis results and experiment results, it was confirmed that the analytical results had good agreement with the experimental results. Also we performed parametric studies about damping properties of the test models. As a result of having identified the damping properties using experiment results, it was found that inner pipe and outer pipe had different damping properties. In this paper, these results were shown.

Journal Articles

Possible low-energy excitations of multipoles in SmRu$$_4$$P$$_{12}$$ probed by muon spin relaxation

Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki*; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; Sato, Hideyuki*

Physica B; Condensed Matter, 404(5-7), p.761 - 764, 2009/04

 Times Cited Count:1 Percentile:6.65(Physics, Condensed Matter)

We report on detailed longitudinal field (LF) $$mu$$SR studies in SmRu$$_4$$P$$_{12}$$ in order to characterize magnetic fluctuations in a magnetically ordered state below $$T_{rm MI}=16.5$$ K. A magnitude and fluctuation rate of the fluctuating field are derived as functions of temperature from LF dependence of the longitudinal relaxation rate. Possible low-energy excitations of magnetic multipoles are discussed.

Journal Articles

Magnetic properties of SmRu$$_{4}$$P$$_{12}$$ probed by $$mu$$SR

Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; Sato, Hideyuki*

Journal of Physics and Chemistry of Solids, 68(11), p.2072 - 2075, 2007/11

 Times Cited Count:1 Percentile:7.92(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Evolution of local magnetic state in SmRu$$_4$$P$$_{12}$$ probed by muon spin relaxation

Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki; Fujimoto, Tatsuya*; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; et al.

Journal of the Physical Society of Japan, 76(5), p.053707_1 - 053707_4, 2007/05

 Times Cited Count:27 Percentile:76.48(Physics, Multidisciplinary)

A filled skutterudite compound SmRu$$_4$$P$$_{12}$$ shows metal-insulatortransition at $$T_{rm MI}$$=16.5K with magnetic anomaly. A possibility of magnetic octupole ordering has been discussed on the basis of multipole degrees of freedom belonging to thecrystalline-electric-field ground state. We investigated local magnetic states in the ordered state by using the muon spin relaxation method. An increase of muon spin relaxation rate was detected in zeroapplied field just below $$T_{rm MI}$$, indicating time-reversal-symmetry breaking in the ordered state. This result suggests that the order parameter includes magnetic octupole and/ordipole. Magnitude of the internal field at the muon site monotonically increases with decreasing temperature, growing steeply below $$T^{prime}$$=3K. The longitudinal relaxation rate has a maximum at around $$T^{prime}$$, suggesting suppression of magnetic fluctuations. We discussed these experimental facts on the basis of the multipoledegrees of freedom.

Journal Articles

Performance study of the cryogenic system for ITER CS model coil

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

JAEA Reports

Effect of Electron Channeling on Damage Production in a Germanium Crystal

Nishida, Takahiko; Izui, Kazuhiko

JAERI-M 6867, 15 Pages, 1977/01

JAERI-M-6867.pdf:0.65MB

no abstracts in English

Oral presentation

Magnetism of SmRu$$_4$$P$$_{12}$$ at low temperature and low field probed by $$mu$$SR

Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki; Fujimoto, Tatsuya; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; et al.

no journal, , 

no abstracts in English

Oral presentation

Anomalous magnetic state in SmRu$$_4$$P$$_{12}$$ detected by muon spin relaxation

Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki; Fujimoto, Tatsuya; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; et al.

no journal, , 

no abstracts in English

Oral presentation

Study of static and dynamic properties of multipoles in $$f$$ electron systems

Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki; Fujimoto, Tatsuya; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; et al.

no journal, , 

no abstracts in English

Oral presentation

Magnetism of SmRu$$_4$$P$$_{12}$$ at low temperature and low field probed by $$mu$$SR

Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki; Fujimoto, Tatsuya; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; et al.

no journal, , 

no abstracts in English

Oral presentation

Possible multipole state of SmRu$$_4$$P$$_{12}$$ probed by $$mu$$SR

Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki*; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; Sato, Hideyuki*

no journal, , 

The filled skutterudite compound SmRu$$_4$$P$$_{12}$$ exhibits a metal-insulator (MI) transition at $$T_{rm MI}$$ $$sim$$ 16.5 K. An entropy release $$sim Rln4$$ below $$T_{rm MI}$$ suggests that the crystalline-electric-field ground state is a $$Gamma_{67}$$ quartet with various multipole degrees of freedom. A possibility of magnetic octupole ordering has been intensively discussed to explain the time-reversal-symmetry breaking, anomalous elastic properties, and a complex field-temperature phase diagram. We will report $$mu$$SR measurements on single crystalline samples of SmRu$$_4$$P$$_{12}$$ to investigate the nature of the multipoles in the ordered state. A remarkable longitudinal relaxation was observed in the ordered state, the magnitude of which was reduced below $$T^{prime}$$ $$sim$$ 3 K. We will discuss possible low-energy excitations of magnetic multipoles in the ordered state and their influence on the local magnetic probe on the basis of symmetry of the multipoles.

26 (Records 1-20 displayed on this page)