Seismic isolation

A possibility of utilization of the rubber-soil mixtures to provide seismic isolation of buildings by using the entire contact surface of the foundation... 

Fig. 9. KALIMER Seismic Isolation Test Program Reactor Building Analyses...

The seismic responses of reactor structures of seismically isolated KALIMER are significantly reduced for accelerations and relative displacements in honzontal direction For the isolation case, the maximum peak acceleration in honzontal direction is same m all structures and components, i e, 0 llg for OBE and 0 22g for SSE The responses are reduced about 14 times in MX. 9 tunes in EMP and 8 times in reactor vessel liner, support barrel, and core compared with those m non-isolated case However, for the vertical direction, significant response amplifications occur ui whole structures This IS due to the vertical structural frequency of 8 1 Hz located in dormnant excitation frequency band of input motion... 

From these results, we can conclude that the seismic isolation provides great reductions of the impact loads as well as the number of contacts at the load pads of core assemblies at the former ring. This can allow the simple design of a core control system. And it is expected that the requirements of the core compaction and reactivity insertion problem can be easily satisfied when an efficient seismic isolation is adapted for the LMR design[9]. 

The vibratory motion is defined according to that prescribed in the guidelines on seismic isolation prepared by the Superior Council of Public Works (Italian Guidelines, 1996). The motion is characterized by a given return time (T = 150, 500 years) to be correlated with the desired performance of the structure during the earthquakes. 

AR162 Verification of analysis methods for predicting the behaviour of seismically isolated nuclear structures. No. 1288, 9 July 2002. 

The above techniques cannot be indifferently applied to each type of equipment of a plant, because their effectiveness depends on the characteristics of the structure to be protected. As a matter of fact, for a cathedral-type furnace (Figure 9a) the seismic isolation can be profitably used by inserting isolators between the superstructure and the base columns. 

Until now, passive control techniques have been used for a very limited number of industrial applications for example, in Europe the isolation technique has been adopted only in a few cases the seismic protection of Petrochemical LNG terminal of Revythousa, Greece (Tajirian, 1998) and of ammoniac tanks, at Visp, in Switzerland by means of elastomeric isolators (Marioni, 1998), Figure 20. Friction Pendulm devices have also been used for the seismic isolation of an elevated steel storage tank of the petrochemical plant of Priolo Gargallo in Sicily (Italy) (Santangelo et al., 2007). 

Fig. 9. a) Cathedral furnace where the seismic isolation can be easily applied, b) Distillation column and adjacent steel frame in which is possible to realize dissipative bracings in the steel frame, dissipative coupling between column and frame, and Timed Mass Damper, linking the equipment placed at several levels of the frame with the same frame using proper isolators. 

Addessi D., Ciampi V. (2001), Ongoing studies for the application of innovative anti-seismic techniques to chemical plant components in Italy, 7th International Seminar on Seismic Isolation, Passive Energy Dissipation and Active Control of Vibrations of Structures, Assisi. 

Calugaru, Vladimir Mahin, Stephen A., (2009), Experimental and analytical studies of fixed-base and seismically isolated liquid storage tanks, 3rd International Conference on... 

Christopoulos C., Filiatrault A., (2006), Principles of Passive Supplemental Damping and Seismic Isolation, lUSSpress, Pavia, Italy... 

Santagelo A, Scibilia N., Stadarelli R., (2007), Seismic Isolation of a tanks at Priolo GargaUo (in Italian), Giornate AICAP 2007,4-6 Ottobre, 2007. 

A conceptual study on the vertical seismic isolation system for FBR components is underway. A series of shaking table tests and analytical worics are included to assess the feasibility of the system. 

Variable Arm Pantograph Type IVTM Seismic Isolation Bearing... 

As the establishment of the design guidelines for seismic base isolation system is in progress or developed in Japan, Italy, and USA, the seismic isolation design guideline for the KALIMER would be selected and modified from those developed by these countries. 

There are a number of equipments and technologies vdiich require R D work for implementation to KALIMER. To name a few, the submerged EM pump, a seismic isolator, high temperature structures, metal friel, passive Curie point shutdown system, and a steam generator. R D work for all of these items require massive investment to the facility and it is desirable to carry out the selected R Ds through an international collaboration if possible. The international collaboration in the systems engineering and methodology development is also needed to support the domestic efforts of Korea for KALIMER development. 

Italy The key issues and tasks in nuclear R D in Italy are focused on the following areas (1) collaboration with General Electric on ALMR (optimization of safety parameters for a fast burner oxide core, studies with the aim of reaching the best burning capability of the PRISM MOD B oxide core, satisfying the safety criteria) (2) seismic isolation systems (guidelines development, seismic isolation tests, analytical studies), and (3) SPX reactor commissioning and service activities. 

The paper presents the progress of the work performed at ENEA for the optimization of the PRISM MODE oxide core in the framework of a collaboration agreement with General Electric. Studies on seismic isolation are outlined. The Italian contribution, mainly by industries, on SPX-1 restart is described. 

The document will be periodically updated by ENEA to include comments and to reflect the advances in the seismic isolation technology development. When a satisfactory degree of consensus among experts is reached, the document will be submitted to Licensing Authorities for approval. 

The qualification procedure specified for the isolation devices may lead to a definition of a standard and to the use of standardized products for seismic isolation design. 

Non-linear finite-element models of high damping rubber bearings have been developed and implemented in the ABAQUS code in the framework of Italian cooperative studies for seismic isolation development. The Hyperelastic models used have been based on the results of tests on rubber specimens. The isolators models are validated through comparison of numerical results with complete bearing test data. 

The aim of seismic isolation is to decrease the drift in the superstructure, and the aim of the present control design is to avoid damage in the isolators and hence the superstructure. From the superstructure s point of view the case with minimum... 

A damper with a fixed damping coefficient will not be able to achieve a similar performance as the presented control method. The best response in far field type earthquakes is established by minimum damping with an extra control force at some time instances near field type earthquakes, on the other hand, appear to be best handled with a fixed base. Therefore, in either case a fixed valued damper will not suffice to produce a desirable structural response. At last, a smartly controlled semiactive damper is able to protect a seismically isolated building from both near and far field type earthquakes. 

Iqbal A (2006) Soft first storey with seismic isolation system. In NZSEE conference, Napier, CDROM paperlD 36... 

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