Response of a Base-isolated Large Liquid Metal Reactor Plant to Seismic Loads PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Response of a Base-isolated Large Liquid Metal Reactor Plant to Seismic Loads PDF full book. Access full book title Response of a Base-isolated Large Liquid Metal Reactor Plant to Seismic Loads by . Download full books in PDF and EPUB format.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 6
Get Book Here
Book Description
In recent years, base isolation has been applied to various civil structures such as bridges and buildings for the purpose of reducing its acceleration to below the level of ground accelerations during seismic events. The basic principal of base isolation is to introduce a soft layer of material between structure foundation to allow a degree of flexibility in horizontal motions which could reduce the seismic accelerations during earthquakes. If base isolation is properly designed, it shifts the fundamental frequency of the structure away from the damaging frequency range of earthquakes. Thus, the seismic loads transmitted to the structure can be greatly reduced. This is particularly important in Liquid Metal Reactor (LMR) plants, because the components of primary system such as reactor vessel and piping loops are designed to be thin-walled structures and have little inherent seismic resistance. Thus, the use of base isolation offers a viable and effective approach that permits the reactor structures to better withstand the seismic loading. This paper deals with the seismic response of a base isolated large-scale LMR plant. The analysis model was based on a preliminary nuclear island layout developed by EPRI during the concept development phase of the large-scale prototype breeder (LSPB) project. The nuclear island has a dimension of 184'-0'' x 210'-6''; the reactor vessel has an ID of 62 ft and an overall length of 70 ft. Two soil conditions have been considered in the analysis. One is a hard-soil site having a shear wave velocity of 6000 ft/s, and the other is a soft-soil site having a shear wave velocity of 2000 ft/s. For comparison purposes, the responses of a conventional plant (unisolated) was also analyzed. 3 figs., 1 tab.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 6
Get Book Here
Book Description
In recent years, base isolation has been applied to various civil structures such as bridges and buildings for the purpose of reducing its acceleration to below the level of ground accelerations during seismic events. The basic principal of base isolation is to introduce a soft layer of material between structure foundation to allow a degree of flexibility in horizontal motions which could reduce the seismic accelerations during earthquakes. If base isolation is properly designed, it shifts the fundamental frequency of the structure away from the damaging frequency range of earthquakes. Thus, the seismic loads transmitted to the structure can be greatly reduced. This is particularly important in Liquid Metal Reactor (LMR) plants, because the components of primary system such as reactor vessel and piping loops are designed to be thin-walled structures and have little inherent seismic resistance. Thus, the use of base isolation offers a viable and effective approach that permits the reactor structures to better withstand the seismic loading. This paper deals with the seismic response of a base isolated large-scale LMR plant. The analysis model was based on a preliminary nuclear island layout developed by EPRI during the concept development phase of the large-scale prototype breeder (LSPB) project. The nuclear island has a dimension of 184'-0'' x 210'-6''; the reactor vessel has an ID of 62 ft and an overall length of 70 ft. Two soil conditions have been considered in the analysis. One is a hard-soil site having a shear wave velocity of 6000 ft/s, and the other is a soft-soil site having a shear wave velocity of 2000 ft/s. For comparison purposes, the responses of a conventional plant (unisolated) was also analyzed. 3 figs., 1 tab.
Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 1032
Get Book Here
Book Description
Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 6
Get Book Here
Book Description
This paper describes the seismic analysis of a 450-MWe pool-type liquid metal reactor (LMR) under 0.3 g SSE ground excitations. It also assess the ultimate inelastic structural capabilities for other beyond-design-basis seismic events. Calculation is focused on a new design configuration where the vessel thickness is reduced considerably compared to the previous design (Ma and Gvildys, 1987). In the analysis, the stress and displacement fields at important locations of the reactor vessel, guard vessel, and support skirt are investigated. Emphasis is placed on the horizontal excitation in which large stress is generated. The possibility of impact between the reactor and guard vessels is examined. In the reactor vessel analysis, the effect of fluid-structure interaction is included. Attention is further given to the maximum horizontal acceleration of the reactor core as well as the relative displacement between the reactor core and the upper internal structure. The Argonne National Laboratory augmented three-dimensional Fluid-Structure Interaction program, FLUSTR-ANL is utilized for performing the base calculation where ground excitation is assumed to be 0.3 g SSE. The Newmark-Hall Ductility modification method was used for the beyond-design-basis seismic events. In both calculations, stress fields generated from the horizontal and vertical excitations are evaluated separately. The resultant stresses due to combined actions of these events are computed by the SRSS method. 4 refs., 5 figs., 2 tabs.
Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 848
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Seismic isolation has been shown to be able to reduce transmitted seismic force and lower response accelerations of a structure. When applied to nuclear reactors, it will minimize seismic influence on the reactor design and provide a design which is less site dependent. In liquid metal reactors where components are virtually at atmospheric pressure but under severe thermal conditions, thin-walled structures are generally used for primary systems. Thin-walled structures, however, have little inherent seismic resistance. The concept of seismic isolation therefore offers a viable and effective approach that permits the reactor structures to better withstand thermal and seismic loadings simultaneously. The majority of published work on seismic isolation deals with use of horizontal isolation system only. In this investigation, however, local vertical isolation is also provided for the primary system. Such local vertical isolation is found to result in significant benefits for major massive components, such as the reactor cover, designed to withstand vertical motions and loadings. Preliminary estimations on commodity savings of the primary system show that, with additional local vertical isolation, the savings could be twice that estimated for horizontal isolation only. The degree of effectiveness of vertical isolation depends on the diameter of the reactor vessel. As the reactor vessel diameter increases, the vertical seismic effects become more pronounced and vertical isolation can make a significant contribution.
Author: Eric Scott Keldrauk
Publisher:
ISBN:
Category :
Languages : en
Pages : 742
Get Book Here
Book Description
The commissioning and construction of new nuclear power plants in the United States has dwindled over the past 30 years despite significant innovation in reactor technology. This is partially due to the ever-increasing seismic hazard estimates, which increases the demand on and risk to nuclear power plant structures. Seismic base isolation is a mature technology which introduces a laterally-flexible and vertically-stiff layer between the foundation and superstructure to significantly reduce the seismic response of the structure, systems, and components therein. Such devices have also been noted to concentrate the displacement response in one plane, reduce higher-mode participation, and provide damping to protect against excessive displacements, all of which aid in increasing safety margins for seismically-isolated nuclear structures. Despite numerous studies analyzing the applicability of seismic base isolation to nuclear power plant structures, some of which are discussed herein, no seismically-isolated nuclear plant has been constructed in the United States. This study presents a time-domain procedure for analyzing the performance of seismically-isolated nuclear structures in response to design-basis earthquake events using ALE3D. The simulations serve as a parametric study to assess the effects of soil column type, seismic isolation model, superstructure mesh, and ground motion selection on global displacements, rotations, and accelerations, as well as internal floor accelerations. Explicit modeling of the soil columns and superstructures enables detailed analysis of soil-structure interaction. The soil columns analyzed have constant properties over the height of the finite element soil mesh and include rock, soft rock, and stiff soil sites, as well as a "no soil" case for comparison. Four separate 3-dimensional seismic isolation bearing models were coded into ALE3D and validated. These include models for friction pendulum, triple friction pendulum, simplified lead rubber, and robust lead rubber bearings. Lastly, two superstructure finite element meshes were considered: a cylindrical plant design meant to represent a typical conceptual design for advanced reactors, and a rectangular plant design meant to represent an advanced boiling water reactor. The ground motions considered include 30 three-component time history records scaled to meet the seismic hazard for the Diablo Canyon nuclear plant. Every combination of soil column, isolator model, and superstructure were subjected to a subset of three of the harshest ground motions, termed the "basic motions", and the combinations which included the rectangular plant design atop the rock soil column were subjected to all 30 motions. The results of the various simulations including accelerations in the soil columns and superstructures as well as displacements and rotations in the isolators and superstructures are presented. The results suggest three possible effects: an isolator-type effect, a soil-type effect, and a slenderness effect. The isolator-type effect refers to significant increases in vertical soil acceleration amplifications, isolator uplift/tension, and global rotations including torsion and overturning for friction bearings in comparison to elastomeric bearings. Additionally it is noted that inclusion of lead plug softening has the effect of increasing peak lateral isolator deformations, especially for the ground motions that naturally induce high-amplitude deformations in the bearings. These results suggest that uplift/tension may be troublesome in high-seismic areas and the use of restrainers should be analyzed as a possible solution. Furthermore, these results reinforce the lateral design displacement estimate procedures for seismically-isolated nuclear structures in ASCE4-11. The results prove that explicit inclusion of the soil column is necessary for proper response characterization and the chosen soil properties greatly affect the efficacy of seismic isolation designs. The soil-type effect comes from observations of comparative simulations which show that, in general, peak isolator uplift/tension and deformation, as well as peak global displacements and rotations including torsion and overturning increase as the soil column becomes less-stiff, regardless of the isolator model or superstructure considered. These results suggest that although seismic isolation can be effective for structures atop a variety of soil columns, it is imperative that a single isolator design only be considered applicable to a corresponding soil column unless extensive analyses prove otherwise for a specific case. Differences in peak response parameters between the two superstructures point to a possible slenderness effect. Specifically, the isolator deformations as well as the global displacements and rotations are observed to increase for the cylindrical superstructure in comparison to the rectangular superstructure cases utilizing the same ground motion, soil column, and isolator model. Should further research reaffirm this effect, a practical limit could be set for superstructure slenderness.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
This paper describes the seismic study of a 450-MWe liquid metal reactor (LMR) under 0.3-g SSE ground excitation. Two calculations were performed using the new design configuration. They deal with the seismic response of the reactor vessel, the guard vessel and support skirt, respectively. In both calculations, the stress and displacement fields at important locations of those components are investigated. Assessments are also made on the elastic and inelastic structural capabilities for other beyond-design basis seismic loads. Results of the reactor vessel analysis reveal that the maximum equivalent stress is only about half of the material yield stress. For the guard vessel and support skirt, the stress level is very small. Regarding the analysis if inelastic structural capability, solutions of the Newmark-Hall ductility modification method show that the reactor vessel can withstand seismics with ground ZPAs ranging from 1.015 to 1.31 g, which corresponds to 3.37 to 4.37 times the basic 0.3-g SSE. Thus, the reactor vessel and guard vessel are strong enough to resist seismic loads. 4 refs., 10 figs., 5 tabs.
Author: James M. Kelly
Publisher:
ISBN:
Category : Nuclear power plants
Languages : en
Pages : 82
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category : Shock (Mechanics)
Languages : en
Pages : 460
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 532
Get Book Here
Book Description
