Required Properties of Seismic Isolation System for Nuclear Power Plants

2010 ◽  
Author(s):  
Satoshi Fujita ◽  
Keisuke Minagawa ◽  
Takeshi Kodaira
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Three Dimensional ◽  
Isolation System ◽  
Seismic Safety ◽  
Isolation Systems ◽  
Rubber Bearings ◽  
Seismic Isolation Systems

In Japan, applications of seismic isolation systems to new generation nuclear power plants and fast breeder reactors have been expected in order to enhance seismic safety. However there are lots of restrictions for design of isolation systems, such as strong design seismic wave, deformation of piping between an isolated structure and a non-isolated structure, and so on. In addition combination of horizontal and vertical isolation has possibility to cause rocking motion if a three-dimensional isolation system is applied. Therefore isolation systems should be designed properly. Moreover the design of seismic isolation system has to consider influence on inner equipment and piping. This paper describes investigation regarding required properties and performance of seismic isolation system for nuclear power plants. The investigation is carried out by numerical analysis. In the analysis, various isolation devices such as friction pendulum bearings and so on are applied as well as natural rubber bearings.

Effect of Nonlinearity of Rubber Bearing on a Seismic Isolated Structure Considering Their Layout

2014 ◽  
Author(s):  
Sebastien Chirez ◽  
Satoshi Fujita ◽  
Keisuke Minagawa
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Response Analysis ◽  
Seismic Safety ◽  
Rubber Bearing ◽  
Isolation Systems ◽  
Set Up ◽  
Rubber Bearings ◽  
Seismic Isolation Systems

In Japan, in order to ensure seismic safety requirements for buildings such as hospitals, nuclear power plants and communication centers for instance, seismic isolation systems have been developed. The most widely used technologies are rubber bearings and oil dampers, which can enhance the protection of equipment or machinery set up in those buildings. However, the isolation performance may face difficulties in case of huge earthquakes because of the nonlinearity of rubber bearings. In a former study of our laboratory, an earthquake response analysis based on the Runge-Kutta-Gill’s method had been carried out in order to assess the behavior of the rubber bearings[1]. In this paper, we use the same method but for further accurate and more realistic simulations, the analytical model has been improved in order to assess the response of rubber bearings depending on their layout when we consider the rocking of the building.

Response Analysis of a Seismic Isolated Structure Considering the Nonlinearity of the Rubber Bearings

2013 ◽  
Author(s):  
Alexandre Borsoi ◽  
Satoshi Fujita ◽  
Keisuke Minagawa
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Industrial Structure ◽  
Response Analysis ◽  
Vertical Load ◽  
Restoring Force ◽  
Seismic Safety ◽  
Rubber Bearings ◽  
Seismic Isolation Systems

In Japan, the application of seismic isolation systems using rubber bearings to industrial structure and new generation Nuclear Power Plants have been considered in order to enhance seismic safety. However, the isolation performance will decline in case of huge earthquakes, because of the nonlinearity of both horizontal and vertical restoring characteristics of the rubber bearings. The horizontal restoring force has a hardening characteristic and the vertical restoring force has a softening characteristic. In addition, the horizontal nonlinearity depends on vertical load, so the interaction between the horizontal and vertical response is important. Consequently, in this paper, the analysis of the nonlinearity of the rubber bearings and the coupling between those two directions will be carried out. Then, after comparing these two approaches, the utility of considering this dependency will be estimated. To do so, a simulation program, based on the Runge-Kutta-Gill’s method has been developed in order to evaluate the seismic response of the isolated structure composed of rubber bearings and oil dampers. The nonlinearity of the rubber bearings is considered, and the coupling of the vertical load and the horizontal hardening has been implemented.

scholarly journals Comparing Rubber Bearings and Eradi-Quake System for Seismic Isolation of Bridges

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5247
Author(s):  
Chang Beck Cho ◽  
Young Jin Kim ◽  
Won Jong Chin ◽  
Jin-Young Lee
Keyword(s):  
Seismic Isolation ◽  
New Technology ◽  
Isolation System ◽  
Seismic Safety ◽  
Response Characteristics ◽  
Rubber Bearing ◽  
Seismic Force ◽  
Isolation Systems ◽  
Rubber Bearings ◽  
Seismic Isolation Systems

Seismic isolation systems have been used worldwide in bridge structures to reduce vibration and avoid collapse. The seismic isolator, damper, and Shock Transmission Unit (SUT) are generally adopted in the seismic design of bridges to improve their seismic safety with economic efficiency. There are several seismic isolation systems, such as Natural Rubber Bearing (NRB), Lead Rubber Bearing (LRB), and the Eradi-Quake System (EQS). EQS as a new technology is expected to effectively reduce both seismic force and displacement, but there is still some need to verify whether it might provide an economical and practical strategy for a bridge isolation system. Moreover, it is important to guarantee consistent performance of the isolators by quality control. A comparative evaluation of the basic properties of the available seismic isolators is thus necessary to achieve a balance between cost-effectiveness and the desired performance of the bridge subjected to extreme loading. Accordingly, in this study, the seismic response characteristics of the seismic isolation systems for bridges were investigated by conducting compressive test and compressive-shear test on NRB, LRB, and EQS.

Research and Development of Three Dimensional Seismic Isolation System Utilized Coned-Disc-Springs With Rubber Bearings

2017 ◽  
Author(s):  
Takayuki Miyagawa ◽  
Tomoyoshi Watakabe ◽  
Tomohiko Yamamoto ◽  
Tsuyoshi Fukasawa ◽  
Shigeki Okamura
Keyword(s):  
Seismic Isolation ◽  
Three Dimensional ◽  
Safety Margin ◽  
Seismic Load ◽  
Isolation System ◽  
Seismic Safety ◽  
Track Record ◽  
Rocking Motion ◽  
Isolation Systems ◽  
Rubber Bearings

The seismic isolation system consisting of laminated rubber bearings is applied to development of the Sodium-cooled Fast Reactor (SFR) in Japan. While rubber bearings as horizontal isolation system have been expected to be ensured seismic safety margin of components installed in reactor building against horizontal seismic load, vertical isolation systems have been also studied in order to tolerate to the seismic load which has been increased steadily. In this paper, the three dimensional seismic isolation system by combining coned disc springs with rubber bearings is proposed as a concept which consists of isolation devices with abundant track record. Analytical study for this system results that the rocking motion can be suppressed by itself without any suppression system and that the mitigation of vertical response can be enough for buckling design of the reactor vessel simultaneously. In particular, it is important that the vertical natural frequency of system is within the range of 3Hz to 5Hz. Besides, layout, size and stacks of coned discs in the unit of system are studied in order to obtain suitable for specification to SFR buildings.

433 Study on Three-Dimensional Seismic Isolation System Applied to Advanced Nuclear Power Plants : Study on Development Planning:Part 5

2005 ◽  
Vol 2005 (0) ◽  
pp. _433-1_-_433-6_
Author(s):  
Kenji TAKAHASHI ◽  
Asao KATOH ◽  
Masaki MORISHITA ◽  
Minoru Fushimi ◽  
Takafumi FUJITA ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Three Dimensional ◽  
Isolation System

scholarly journals Seismic Performance of Piping Systems of Isolated Nuclear Power Plants Determined by Numerical Considerations

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4028
Author(s):  
Sungjin Chang ◽  
Bubgyu Jeon ◽  
Shinyoung Kwag ◽  
Daegi Hahm ◽  
Seunghyun Eem
Keyword(s):  
Seismic Response ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Mesh Size ◽  
Seismic Fragility ◽  
Response Analysis ◽  
Seismic Safety ◽  
Seismic Isolation Systems

The interest in the seismic performance of nuclear power plants has increased worldwide since the Fukushima Daiichi Nuclear Power Plant incident. In Korea, interest in the seismic safety of nuclear power plants has increased since the earthquake events in Gyeongju (2016) and Pohang (2017). In Korea, studies have been conducted to apply seismic isolation systems to ensure seismic safety while minimizing the design changes to nuclear power plants. Nuclear power plants with seismic isolation systems may have a higher seismic risk due to the failure of the piping system in the structure after a relatively large displacement. Therefore, it is essential to secure the seismic safety of pipes for the safe operation of nuclear power plants. The seismic safety of pipes is determined by seismic fragility analysis. Seismic fragility analysis requires many seismic response analyses because it is a statistical approach to various random variables. Typical numerical conditions affecting the seismic response analysis of pipes are the convergence conditions and mesh size in numerical analysis. This study examined the change in the seismic safety of piping according to the numerical conditions. The difference in the seismic response analysis results of the piping according to the mesh size was analyzed comparatively. In addition, the change in the seismic fragility curve of the piping according to the convergence conditions was investigated.

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