Study on Three-Dimensional Seismic Isolation System for Next Generation Nuclear Power Plant: Independent Cable Reinforced Rolling-Seal Air Spring

2004 ◽  
Author(s):  
Mitsuru Kageyama ◽  
Yoshihiko Hino ◽  
Satoshi Moro
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Base Isolation ◽  
Three Dimensional ◽  
Outer Diameter ◽  
Next Generation ◽  
Air Spring ◽  
Isolation System ◽  
Rubber Sheet

In Japan, the development of the next generation NPP has been conducted in recent years. In the equipment/piping design of the plant, seismic condition has been required much more mitigate than before. So, the three-dimensional (abbreviation to 3D) seismic isolation system development has also been conducted since 2000. The superlative 3D base isolation system for the entire building was proposed. The system is composed of cable reinforced air springs, rocking arresters and viscous dampers. Dimensions of the air spring applied to the actual power plant are 8 meters in the outer-diameter and 3.5 meters in height. The allowable half strokes are 1.0 meters in horizontal and 0.5 meters in vertical respectively. The maximum supporting weight for a single device is 70 MN. The inner design air pressure is about 1.8MPa. This air spring has a distinguishing feature, which realizes 3D base isolation with a single device, whose natural periods are about 4 seconds in horizontal and about 3 seconds in vertical. In order to verify the 3D performance of this system, several feasibility tests were conducted. Firstly, 3D shaking table tests were conducted. The test specimen is scaled 1/4 of the actual device. The outer diameter and inner air pressure of air spring is 2 meters and 0.164 MPa. Next, a pressure resistant test for the sub cable, textile sheet and rubber sheet, which composed air spring, were conducted as a full scale model test. Then, air permeation test for the rubber sheet was also conducted. As a result, the proposed system was verified that it could be applied to the actual nuclear power plants.

Development of Three-Dimensional Seismic Isolation Technology for Next Generation Nuclear Power Plant in Japan

2004 ◽  
Author(s):  
K. Inoue ◽  
M. Morishita ◽  
T. Fujita
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Base Isolation ◽  
Three Dimensional ◽  
3D Seismic ◽  
Next Generation ◽  
Air Spring ◽  
Isolation System ◽  
Earthquake Loads ◽  
Base Isolation System

Mitigation of earthquake loads by seismic isolation technology is very promising for enhanced safety and economy of the next generation nuclear reactors, through rationalized and simplified design of structures, systems and components. The horizontal base isolation with laminated rubber bearings is a proven technology and its application has been widely spread including nuclear facilities. On the other hand, significantly increased benefit of mitigated seismic loads is expected with three-dimensional (abbreviated 3D) seismic isolation, since the earthquake loads are inherently three-dimensional and the vertical component of the earthquake load sometimes plays an important role in the structural design of reactor components. From these points of view, a research project has been undertaken for the development of 3D seismic isolation technology, under the sponsorship of the Ministry of Economy, Trade and Industry of the Japanese government. It was presented in a former conference that two types of 3D seismic isolation systems were applicable to the next generation nuclear power plants. One is 3D base isolation of a whole nuclear island, and the other is a vertical isolation system for main components with horizontal base isolation system. Among a number of proposed concepts, three were promising ideas for the 3D base isolation system (or device), i.e., “hydraulic 3D base isolation system”, “independent cable reinforced rolling-seal air spring”, and “rolling seal type air spring”. Then the last idea, i.e., “rolling seal type air spring”, was selected from above three ideas for further development. In this paper, current status of this R&D project are firstly shown. Next, the performance requirements for 3D isolation system and devices are shown. Then the developing targets for 3D isolation technology are shown. Furthermore, future plan of the project is provided.

Development of Three-Dimensional Seismic Isolation Technology for Next Generation Nuclear Power Plant Applications

2005 ◽  
Author(s):  
K. Takahashi ◽  
K. Inoue ◽  
M. Morishita ◽  
T. Fujita
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Base Isolation ◽  
Three Dimensional ◽  
Scale Model ◽  
Isolation System ◽  
The Real ◽  
Reactor Building

Seismic isolation technology plays an important role in the area of architect engineering, especially in Japan where earthquake comes so often. This technology also makes the nuclear power plant rationalized. The horizontal base isolation with laminated rubber bearings has already been proven its effectiveness. These days, seismic isolation technology is expected to mitigate even the vertical load, which affects the structural design of primary components. Seismic isolation system has possibility to improve the economical situation for the nuclear power plant. From these points of view, a research project has been proceeded to realize practical three dimensional seismic isolation systems from 2000 to 2005 under the sponsorship of the Ministry of Economy, Trade and Industry of the Japanese government. The isolation system is developed for the supposed “Fast Breeder Reactor (abbreviated FBR)” of the next generation. Two types of seismic isolation systems are developed in the R&D project. One is a three-dimensional base isolation for a reactor building (abbreviated 3D SIS) and the other is a vertical isolation for main components with horizontal base isolation of the reactor building (abbreviated V. +2D SIS). At first step of the R&D, requirements and targets of development for the seismic isolation system were identified. Seismic condition for R&D was discussed based on the real seismic response. Vertical natural frequency and damping ratio required to the system were introduced from the response to the seismic movement. As for 3D SIS, several system concepts were proposed to satisfy the requirements and targets. Through discussions and tests on performance, reliability, applicability, maintainability, “Rolling seal type air spring system with hydraulic anti-rocking devices” was decided to be developed. Verification shaking tests with the 1/7 scale model of the system and analysis for applicability to the real plant are conducted. The result shows that the system is able to support the reactor building, to suppress the rocking motion and to mitigate the vertical seismic load. As for V.+2D SIS, coned disk spring device was selected at the beginning of R&D. Performance tests of the elements, which include common deck movement, were conducted and the system applicability to the plant is confirmed. Verification tests were conducted with 1/8 scale model of the system and the result proves the applicability to the real plant.

Three Dimensional Seismic Isolation System for Next-Generation Nuclear Power Plant With Rolling Seal Type Air Spring and Hydraulic Rocking Suppression System

2005 ◽  
Author(s):  
Takahiro Shimada ◽  
Junji Suhara ◽  
Kazuhiko Inoue
Keyword(s):  
Dynamic Loading ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Base Isolation ◽  
Three Dimensional ◽  
Loading Test ◽  
Isolation System ◽  
Ability Test ◽  
Base Isolation System ◽  
Suppression System

Three dimensional (3D) seismic isolation devices have been developed to use for the base isolation system of the heavy building like a nuclear reactor building. The developed seismic isolation system is composed of rolling seal type air springs and the hydraulic type springs with rocking suppression system for vertical base isolation device. In horizontal direction, the same laminated rubber bearings are used as horizontal isolation device for these systems. The performances and the applicability have already been evaluated by the technical feasibility tests and performance tests for each system. In this study, it was evaluated that the performance of the 3D base isolation system with rolling seal type air springs combined with hydraulic rocking suppression devices. A 1/7 scaled model of the 3D base isolation devices were manufactured and some performance test were executed for each device. For the rolling seal type air springs, dynamic loading test was executed with a vibration table, and pressure resistant ability test was executed for reinforced air springs. In the dynamic loading test, it is confirmed that the natural period and damping performance were verified. In the pressure resistant ability test, it is confirmed that the air springs had sufficient strength. For the hydraulic rocking suppression system, forced dynamic loading test was carried out in order to measure the frictional and oil flow resistance force on each cylinder. And the vibration table tests were carried out with supported weight of 228 MN in order to evaluate and to confirm the horizontal and vertical isolation performance, rocking suppression performance, and the applicability of the this seismic isolation system as the combined system. 4 rolling seal type air springs and 4 hydraulic load-carrying cylinders with rocking suppression devices supported the weight. As a result, the proposed system was verified that it could be applied to the actual nuclear power plant building to be target.

Development of Cable Reinforced 3-Dimensional Base Isolation Air Spring

2002 ◽  
Author(s):  
Mitsuru Kageyama ◽  
Tsutomu Iba ◽  
Takahiro Somaki ◽  
Hisako Hino ◽  
Katsuhiko Umeki
Keyword(s):  
Power Plant ◽  
Base Isolation ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Air Pressure ◽  
Horizontal Direction ◽  
Outer Diameter ◽  
Air Spring ◽  
Steel Cable ◽  
3 Dimensional

In Japan, the study on the development of a 3-dimensional base isolation system to be applied to a nuclear power plant, which requires supreme safety against severe earthquakes, has been carried out since 2000. An idea with the concept of a cable reinforced air spring was proposed as the 3-dimensional base isolation device. The dimension of the air spring applying to the actual power plant is 9 meters in the outer-diameter and 3.5 meters in height. The allowable half strokes are respectively 1.5 meters for the horizontal direction and 0.5 meters for the vertical directions. The supporting weight for a single device is 52MN, where the inner air pressure is about 1.2MPa. This device enables to realize three-dimensional base isolation with a single device, whose characteristics is a natural period of over 4 seconds in the horizontal direction and over 3 seconds in the vertical direction. Furthermore, this device does not require precision mechanical parts just common building materials, which are steel, cable wire, polyester fabric and a rubber sheet. Therefore, the construction cost for this device could be reduced effectively. In order to confirm the performance of the proposed device, experimental tests using the three dimensional shaking table were carried out on the proposed cable reinforced 3-dimensional base isolation air spring, whose outer diameter is 2 meters, being 1/4.5 scale of the actual size. The weight of approximately 392kN including a 4-story steel frame was loaded on the test specimen in order to create inner air pressure of 0.157MPa. As a result, the device was confirmed to function smoothly in three dimensions with natural periods of 1.8 seconds in the horizontal direction and 1.4 seconds in the vertical direction, and is considered that the proposed system can be applied to actual power plants.

Experimental Study on Vertical Component Seismic Isolation System With Coned Disk Spring

2005 ◽  
Author(s):  
S. Kitamura ◽  
S. Okamura ◽  
K. Takahashi
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Base Isolation ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
Vertical Component ◽  
Shaking Table ◽  
Scale Model ◽  
Test Model ◽  
Isolation System

In Japan, several kinds of three-dimensional seismic isolation system for next-generation nuclear power plant such as fast reactors have been studied in recent years. We proposed a structural concept of a vertical component isolation system, assuming a building adopting a horizontal base isolation system. In this concept, a reactor vessel and major primary components are suspended from a large common deck supported by isolation devices consisting of large coned disk springs. In order to verify the isolation performance of the vertical component isolation system, 1/8 series of shaking table tests using a scale model were conducted. The test model was composed of 4 vertical isolation devices, common deck and horizontal load suspension system. For the design earthquake, the system smoothly operated, and sufficient isolation characteristics were shown. The simulation analysis results matched well the test results, so the validity of the design technique was able to be verified. As the result, the prospect that the vertical isolation system applied to the FBR plant could technically realize was obtained.

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