A Study on improvement of three-dimensional seismic analysis method of nuclear building using a large-scale observation system, 2; Analysis of local response of the reactor building based on artificial waves

Nishida, Akemi; Kawata, Manabu; Choi, B.; Kunitomo, Takahiro; Shiomi, Tadahiko; Iigaki, Kazuhiko; Yamakawa, Koki*

Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 10 Pages, 2024/03

no abstracts in English

Construction of large-scale observation system for improvement of three-dimensional seismic analysis method for nuclear buildings

Nishida, Akemi; Kawata, Manabu; Choi, B.; Iigaki, Kazuhiko; Shiomi, Tadahiko; Li, Y.

Proceedings of 2023 International Congress on Advanced in Nuclear Power Plants (ICAPP 2023) (Internet), 10 Pages, 2023/04

Our research and development are aimed at improving the accuracy of the three-dimensional seismic evaluation analysis method for nuclear buildings, which contributes to the probabilistic risk assessment caused by earthquakes (seismic PRA), using actual seismic observation records in collaboration with the Nuclear Regulation Authority since 2019. In this study, we constructed a large-scale observation system that enabled simultaneous measurements at multiple positions during earthquakes or against artificial waves. The accelerometers of the observation system were installed on/in the soil, floors, and on the walls of the nuclear building. This paper presents an outline of the large-scale observation system and the findings obtained from the analysis of the seismic observation records acquired using the system.

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 (ICONE 28) (Internet), 6 Pages, 2021/08

https://doi.org/10.1115/ICONE28-64337

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.

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 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.

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.

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.

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.

Possible low-energy excitations of multipoles in SmRuP 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

https://doi.org/10.1016/j.physb.2008.11.179

We report on detailed longitudinal field (LF) SR studies in SmRuP in order to characterize magnetic fluctuations in a magnetically ordered state below 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.

Evolution of local magnetic state in SmRuP 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

https://doi.org/10.1143/JPSJ.76.053707

A filled skutterudite compound SmRuP shows metal-insulatortransition at =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 , 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 =3K. The longitudinal relaxation rate has a maximum at around , suggesting suppression of magnetic fluctuations. We discussed these experimental facts on the basis of the multipoledegrees of freedom.

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