Development of Seismic Isolation Systems for Sodium-Cooled Fast Reactors in Japan

2016 ◽  
Author(s):  
Nobuchika Kawasaki ◽  
Tomoyoshi Watakabe ◽  
Takashi Wakai ◽  
Tomohiko Yamamoto ◽  
Tsuyoshi Fukasawa ◽  
...  
Keyword(s):  
Natural Frequency ◽  
Seismic Isolation ◽  
Reactor Core ◽  
Fast Reactors ◽  
Isolation System ◽  
Static Tests ◽  
Isolation Systems ◽  
Rubber Bearings ◽  
Seismic Isolation Systems ◽  
Suppression System

Sodium-cooled Fast Reactors (SFRs) have components with thinner walls as compared with light water reactors, although Japan is an earthquake-prone country. Thus, seismic isolation systems have been conventionally employed in SFR system design to reduce seismic forces on the systems in Japan. Implementation of seismic design in the reactor core and buckling design in the reactor vessel requires 8 Hz (or less) vertical frequency’s isolation system being applied. This paper introduces three isolation concepts to achieve the frequency. The isolation systems, which enable vertical 8 Hz natural frequency, comprise thicker laminated rubber bearings (TRBs). By combining coned disk springs with TRBs, vertical natural frequency is in a range from roughly 3 Hz to 5 Hz. Combining pneumatic springs to RBs and adding the rocking suppression system, vertical natural frequency becomes under 1 Hz. All isolation systems need horizontal damping like oil dampers. A vertical 8 Hz isolation system with TRBs and oil dampers is under development in Japan as a principal isolation concept. This system was selected because of its simple configuration and fewer issues to be resolved in the development. Since TRBs and oil dampers are basic isolation elements, they can be applied to other isolation systems. The response acceleration of 5 Hz vertical isolation is 50% of that of 8 Hz based on the analytical survey. A series of static tests of coned disk springs was carried out to confirm design equations. Based on these knowledge, 5 Hz vertical isolation system with TRBs and the coned disk springs can be designed. The response acceleration of 1 Hz vertical isolation is 10% of that of 8 Hz. A rocking suppression system was studied in the past, and the further simplification of this system is the largest challenge for this concept. These three isolation concepts are isolation candidates for SFRs in Japan. To obtain enough seismic margins for each plant site, these isolation systems need to be developed.

Study on Characteristics and Effects of Seismic Isolation System of Vertically Utilized Coiled Springs

2007 ◽  
Author(s):  
Tsuyoshi Fukasawa ◽  
Akihiro Kinoshita ◽  
Satoshi Fujita
Keyword(s):  
Analytical Model ◽  
Seismic Isolation ◽  
304 Stainless Steel ◽  
Restoring Force ◽  
Isolation System ◽  
Static Tests ◽  
Coiled Spring ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Isolation Performance

In recent years many structures employing seismic isolation systems have been constructed in Japan, the practical concern on the cost of seismic isolation systems has heightened. This paper describes the research and development of a new seismic isolation system using vertically utilized elastic and elasto-plastic coiled spring, and discusses analytical model for coiled spring. The basic concept of the earthquake isolation system that was constituted of bearing, restoration and damping elements is to realize cost effective design without any reduction in isolation performance. The restoration and damping elements of the isolation system were constituted by two types of coiled springs. The horizontal static tests were performed to evaluate the restoring characteristic and the mechanical model of elastic and elasto-plastic coiled spring. The restoration element of elastic coiled springs was made of using the two types of materials JIS SUP9 steel and JIS SUS 304 stainless steel. The elasto-plastic coiled springs of damping element also was made of using the two types of JIS SS 400 steel and JIS SWRM 17 steel. The characteristics of these coiled springs such as transverse stiffness and hysteretic damping and the validity of the analytical model were clarified through the static tests. Furthermore the response analyses based on the restoring force characteristics of experimental results were carried out to assess the isolation performance of this system.

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.

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.

scholarly journals Seismic isolation system of two hinged arch suspended-deck bridge: a case study on Kalikuto bridge - Indonesia

2020 ◽  
Vol 156 ◽  
pp. 05024
Author(s):  
Tri Suryadi ◽  
Arvila Delitriana ◽  
Zdenek Fukar ◽  
Rusri Tjendana
Keyword(s):  
Seismic Isolation ◽  
Performance Tests ◽  
Isolation System ◽  
Expansion Joints ◽  
Lead Rubber Bearings ◽  
Design Requirements ◽  
Isolation Systems ◽  
Rubber Bearings ◽  
Seismic Isolation Systems

Seismic isolation systems are widely used in buildings, bridges, and industrial structures all over the world. The system is known for the efficiency to reduce earthquake demand and thus provide better seismic performance of the structures. In particular to application in an arch suspended-deck bridge, seismic isolation system can be a solution for the seismic resisting system due to the incapability of the cable hangers to transfer horizontal forces from excitation mass on the hanging deck to the main compression arches. Kalikuto arch bridge that is built in 2018 has implemented both Lead Rubber Bearings and Seismic Rubber Expansion Joints as the part of its seismic resisting system. These two seismic isolation devices were designed and engineered accurately to fulfil the seismic design requirements of the Kalikuto bridge. Finally, several performance tests were conducted to evaluate the design compliance of the manufactured devices.

Seismic Isolation Analysis on Long-Span Platform Bridge Connecting Twin-Tower Structures

2011 ◽  
Vol 255-260 ◽  
pp. 1225-1229
Author(s):  
Huang Sheng Sun ◽  
Li Nuo Cheng ◽  
Shi Hai Chen
Keyword(s):  
Seismic Isolation ◽  
Seismic Responses ◽  
One Pot ◽  
Isolation System ◽  
High Position ◽  
Long Span ◽  
Steel Truss ◽  
Story Drift ◽  
Isolation Systems ◽  
Rubber Bearings

In order to mitigate the seismic response of twin-tower structure linked by a steel truss platform bridge, as well as to reduce temperature force in the steel truss, eight groups of combined isolation system, each consisting of one pot-type bearing and four rubber bearings, were designed to connect the upper platform bridge to the lower supporting reinforced concrete towers. The features and working principles of the high-position isolation system were described. Then the seismic responses, including displacement, story drift and floor acceleration, of the structure with the isolation systems were calculated and compared with those of the structure with hinge joints in lieu of isolation. It is found that both the structural seismic responses and the temperature forces in the large-span mega-truss structure can be reduced by the high-position isolation system.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 3 — Seismic Response of Crossover Piping for Seismic Isolation System

2014 ◽  
Author(s):  
Akihito Otani ◽  
Teruyoshi Otoyo ◽  
Hideo Hirai ◽  
Hirohide Iiizumi ◽  
Hiroshi Shimizu ◽  
...  
Keyword(s):  
Seismic Response ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Response Spectrum ◽  
Time History ◽  
Response Analysis ◽  
Isolation System ◽  
Isolation Systems ◽  
Seismic Isolation Systems

This paper, which is part of the series entitled “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”, shows the linear seismic response of crossover piping installed in a seismically isolated plant. The crossover piping, supported by both isolated and non-isolated buildings, deforms with large relative displacement between the two buildings and the seismic response of the crossover piping is caused by two different seismic excitations from the buildings. A flexible and robust structure is needed for the high-pressure crossover piping. In this study, shaking tests on a 1/10 scale piping model and FEM analyses were performed to investigate the seismic response of the crossover piping which was excited and deformed by two different seismic motions under isolated and non-isolated conditions. Specifically, as linear response analysis of the crossover piping, modal time-history analysis and response spectrum analysis with multiple excitations were carried out and the applicability of the analyses was confirmed. Moreover, the seismic response of actual crossover piping was estimated and the feasibility was evaluated.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 4 — Failure Behavior of Crossover Piping for Seismic Isolation System

2014 ◽  
Author(s):  
Teruyoshi Otoyo ◽  
Akihito Otani ◽  
Shunsuke Fukushima ◽  
Masakazu Jimbo ◽  
Tomofumi Yamamoto ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Low Cycle Fatigue ◽  
Response Analysis ◽  
Failure Behavior ◽  
Isolation System ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Failure Location

This paper provides a part of the series titled “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. This part shows the failure behavior of crossover piping installed in a seismic isolated plant. The considered crossover piping is supported on one side by an isolated building and by a non-isolated building on the other side. During an earthquake, the piping structure is deformed due to the large relative displacements between the two buildings and at the same time excited by the different building seismic responses. Therefore, the high-pressure crossover piping structure requires both flexibility and strength. In this study, 1/10 scaled shaking tests and FEM analyses have been performed to investigate the failure behavior of the crossover piping, where both seismic motions and excitations have been taken into account. It was confirmed that the failure occurs at the piping elbow through low cycle fatigue. Moreover, the results of the elastic-plastic response analysis, which simulates an extreme level of excitation corresponding to more than three times the design level, are in good agreement with the test results. The simulation also succeeded in predicting the experimental failure location.

Study of Dimension Variation Effect on a Batter Piled Wharf Structure with Seismic Isolation Systems

2020 ◽  
Vol 987 ◽  
pp. 10-14
Author(s):  
Jeffry Fendy ◽  
Josia I Rastandi ◽  
Widjojo A. Prakoso ◽  
Jessica Sjah
Keyword(s):  
Seismic Isolation ◽  
Seismic Zone ◽  
Natural Period ◽  
Isolation System ◽  
Lateral Resistance ◽  
Study Case ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Batter Piles ◽  
Primary Lateral

In a conventional wharf design, batter piles are incorporated in the design as a primary lateral resistance element, however in recent years it is mostly discouraged to use batter piles in the design of wharf structure, especially in higher seismic zone. The use of seismic isolation in the design of wharf structure has been introduced since 2005 in UFC 4-152-01 code as an alternative design for wharf structure, from several studies it is shown that the usage of seismic isolation systems in wharf design has offered many benefits either in new design or structure retrofitting design. The objective of this research is to study the application of seismic isolation system on wharf structure with batter piles, with study case of the wharf design on Kendari, Sulawesi Tenggara, Indonesia. This objective will be achieved by comparing the length per width (L/W) ratio of wharf structure model to evaluate base reaction, natural period and deflection of structure, from these results, a clearer understanding about the advantages of seismic isolation system in wharf structure, so it will be encouraging the application of seismic isolation systems.

Application of Seismic Isolation Systems to High-Raised Houses in Lowland Regions

2014 ◽  
Author(s):  
H.-C. Su ◽  
C. S. Tsai
Keyword(s):  
Seismic Isolation ◽  
Water Levels ◽  
Experimental Results ◽  
Isolation System ◽  
Flood Resistance ◽  
Property Loss ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Rich Countries ◽  
Flood Prone Areas

According to the statistics of the World Bank between years 1970–2010, most economy losses caused by disasters in rich countries were due to floods and earthquakes. The East Asia was the most disastrous area in terms of the death toll caused by earthquakes, which proved that the earthquake is unpredictable. To cope with the crisis of the rise of the sea level, the concept of Marine Cities has been proposed. The most famous one among these concepts is the Dutch amphibious house. People living in earthquake and flood prone areas should be aware of the threat from oceans. Therefore, Ministry of Interior in Taiwan passed the rule 4 No. 2 in the chapter of the design and construction regulations to allow the use of high-raised buildings for reducing life and property loss. Furthermore, the most threatening natural hazards we are facing over a long period of time are floods and earthquakes. When are focusing on the flood resistant buildings in flood-prone areas, we should also aim at the prevention of earthquake disasters. The purpose of this study is to simulate the seismic behavior of the high-raised structures with different water levels, which are capable of flood resistance. We also propose a new seismic isolation system for these structures and study its efficiency in protecting these types of structures from earthquake damage. It appears from experimental results that the seismic responses of high-raised houses have been significantly reduced by the proposed device. Experimental results also disclosed that the proposed concept in this study is feasible for protecting structures in lowlands from damage resulting from floods as well as earthquakes.

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