Attempt to estimate the creep characteristics of thick laminated rubber bearings installed in a vibration isolation building based on long-term observation results

Masaki, Nobuo*; Murota, Nobuo*; Kato, Koji*; Okamura, Shigeki; Yamamoto, Tomohiko; Uchita, Masato*; Fujita, Satoshi*

Nihon Kenchiku Gakkai Gijutsu Hokokushu, 31(78), p.687 - 692, 2025/06

https://doi.org/10.3130/aijt.31.687

Creep characteristic of the thick laminated rubber bearing made of natural rubber installed in the actual vibration isolation building for 55.2 years could be estimated by using existing measurement data and newly measurement data. Creep measurement data sets were examined by simple regression equation of recommended by JIS K6410-2. Regression analysis showed that the average creep displacement characteristics could be described by a power law. Average creep displacement of the thick laminated rubber bearings installed the building for 60 years was estimated 3.4 mm by the regression equation. The method of JIS K6410-2 is useful for forecasting creep displacement.

Research and development of three-dimensional isolation system for sodium cooled fast reactor, 9; Evaluating seismic isolation performance through seismic response analysis

Fukasawa, Tsuyoshi*; Somaki, Takahiro*; Yukawa, Masaki*; Hirayama, Tomoyuki*; Watakabe, Tomoyoshi; Yamamoto, Tomohiko; Okamura, Shigeki; Miyazaki, Masashi; Uchita, Masato*; Miyagawa, Takayuki; et al.

Proceedings of the ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 10 Pages, 2024/07

https://doi.org/10.1115/PVP2024-121899

Research and development of three-dimensional isolation system for sodium cooled fast reactor, 7; Development summary of three-dimensional isolation system

Watakabe, Tomoyoshi; Yamamoto, Tomohiko; Okamura, Shigeki; Miyazaki, Masashi; Miyagawa, Takayuki; Uchita, Masato*; Hirayama, Tomoyuki*; Somaki, Takahiro*; Yukawa, Masaki*; Fukasawa, Tsuyoshi*; et al.

Proceedings of the ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 10 Pages, 2024/07

To secure the seismic safety of the thin-walled mechanical components and piping under a severe design earthquake level, employing a three-dimensional (3D) seismic isolation system has been planned in a sodium-cooled fast reactor. The development results of the 3D isolation system have been reported in previous papers so far. Its update is reported in Part 7 to Part 9. Part 7 describes the overview of the development, the test plan of the isolation system in the assembled state of each element, and the performance of individual isolation elements. In part 8, the performance of the isolation device that each element was assembled into was investigated through loading tests. Part 9 reports analytical studies by an analysis model validated based on the insight of the test results.

Fundamental evaluation of hydrogen behavior in sodium for sodium-water reaction detection of sodium-cooled fast reactor

Yamamoto, Tomohiko; Kato, Atsushi; Hayakawa, Masato; Shimoyama, Kazuhito; Ara, Kuniaki; Hatakeyama, Nozomu*; Yamauchi, Kanau*; Eda, Yuhei*; Yui, Masahiro*

Nuclear Engineering and Technology, 56(3), p.893 - 899, 2024/03

https://doi.org/10.1016/j.net.2023.10.043

Development of seismic isolation system for sodium-cooled fast reactors using high load and high-velocity loading machines

Fukasawa, Tsuyoshi*; Yamamoto, Tomohiko; Uchita, Masato*; Hirayama, Tomoyuki*

Dai-10-Kai Kozobutsu No Anzensei, Shinraisei Ni Kansuru Kokunai Shimpojiumu (JCOSSAR2023) Koen Rombunshu (Internet), p.135 - 142, 2023/10

https://doi.org/10.60316/jcossar.10.0_135

Horizontal seismic isolation systems have been studied for Sodium-Cooled Fast Reactors to improve their seismic resistance. However, challenges arise in reducing seismic forces not only in the horizontal direction but also in the vertical direction. The authors have developed a new three-dimensional seismic isolation system to address this issue. A 1/2-scale test specimen was fabricated, and the force-displacement relationships were examined using static loading tests with a maximum axial force of 8000 kN to evaluate the feasibility of this design. Moreover, a horizontal oil damper was fabricated as a horizontal damping element, and its damping force was assessed through excitation tests with a maximum velocity of 2.7 m/s. This paper reports the findings of these tests.

Experiment of floating seismic isolation system

Mori, Takashi*; Shimada, Takahiro*; Kai, Satoru*; Otani, Akihito*; Yamamoto, Tomohiko; Yan, X.

Proceedings of the ASME 2023 Pressure Vessels and Piping Conference (PVP 2023) (Internet), 8 Pages, 2023/07

https://doi.org/10.1115/PVP2023-102224

Status of development in the 3D seismic isolation applied to SFRS

Yamamoto, Tomohiko; Watakabe, Tomoyoshi; Miyazaki, Masashi; Miyagawa, Takayuki*; Yokoi, Shinobu*; Okamura, Shigeki*; Fukasawa, Tsuyoshi*; Fujita, Satoshi*

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 7 Pages, 2023/05

https://doi.org/10.1299/jsmeicone.2023.30.1149

Evaluation of hydrogen behavior in sodium for sodium-water reaction detection of sodium-cooled fast reactor

Yamamoto, Tomohiko; Kato, Atsushi; Hayakawa, Masato; Shimoyama, Kazuhito; Ara, Kuniaki; Hatakeyama, Nozomu*; Yamauchi, Kanau*; Eda, Yuhei*; Yui, Masahiro*

Proceedings of 2023 International Congress on Advanced in Nuclear Power Plants (ICAPP 2023) (Internet), 6 Pages, 2023/04

Sodium-cooled Fast Reactors

Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

https://shop.elsevier.com/books/sodium-cooled-fast-reactors/morishita/978-0-12-824076-2

This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.

Study on vertical restoring force device using disc springs; Examination of optimum combination of disc spring units and identification method of hysteresis loop

Fukasawa, Tsuyoshi*; Somaki, Takahiro*; Miyagawa, Takayuki*; Uchita, Masato*; Yamamoto, Tomohiko; Ishizuka, Futoshi*; Suzuno, Tetsuji*; Okamura, Shigeki*; Fujita, Satoshi*

Kozo Kogaku Rombunshu, B, 68B, p.462 - 475, 2022/04

https://doi.org/10.3130/aijjse.68B.0_462