scholarly journals Generation of Uniform Hazard Spectrum Based on the Stochastic Method of Simulating Ground Motion and Its Use in Nuclear Power Plants

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Xueming Zhang ◽  
Weiming Yan ◽  
Haoxiang He ◽  
Yunlun Sun ◽  
Shicai Chen
Keyword(s):  
Stochastic Simulation ◽  
Nuclear Power ◽  
Power Plants ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Site Effect ◽  
Element Model ◽  
Simulation Method ◽  
Stochastic Method ◽  
Uniform Hazard Spectrum

To obtain an accurate uniform hazard spectrum (UHS), this paper proposes combining a stochastic simulation with probabilistic seismic hazard analysis. The stochastic method fully accounts for the effect of the source mechanism, path, and site effect. Historical ground motions in the site specific to the nuclear power plant (NPP) are simulated, and a UHS with an equal exceeding probability is proposed. To compare the seismic performance of the NPP under different ground motions generated by the existing site spectrum (SL-2), the UHS generated by the safety evaluation report, and the US RG1.60 spectrum, respectively, a three-dimensional finite element model is established, and dynamic analysis is performed. Results show that the structural responses to different spectra varied; the UHS response was slightly larger than that of RG1.60. This finding is relatively more reasonable than prior research results. The UHS generated using the stochastic simulation method can provide a reference for the seismic design of NPPs.

A Simulation Method of PID Tuning with Process Modeling in Operating Nuclear Power Plants

2014 ◽  
Vol 63 (4) ◽  
pp. 290-294
Author(s):  
Moon-Gi Min ◽  
Chang-Gyu Jung ◽  
Kwang-Hyun Lee ◽  
Jae-Ki Lee ◽  
Hee-Je Kim
Keyword(s):  
Process Modeling ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Simulation Method ◽  
Pid Tuning

Spectral Matching of Real Ground Motions: Applications to Horizontally Irregular Systems in Elastic Range

2014 ◽  
Vol 17 (11) ◽  
pp. 1623-1638 ◽  
Author(s):  
R. Roy ◽  
P. Thakur ◽  
S. Chakroborty
Keyword(s):  
Ground Motion ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Near Field ◽  
Spectral Matching ◽  
Uniform Hazard Spectrum ◽  
Elastic Range ◽  
Conditional Mean Spectrum ◽  
Performance Based Seismic Design ◽  
Irregular Systems

In the context of performance-based seismic design (PBSD), ground motions are often scaled to certain convenient target spectra derived from probabilistic seismic hazard analysis (PSHA). While Uniform Hazard Spectrum (UHS) is more widely used, Conditional Mean Spectrum (CMS) is recently proposed to be more desirable for scaling of real accelerograms. In this backdrop, a set of near-field and far-field ground motions are spectrally scaled, using wavelets, to both UHS and CMS. Seismic demand of horizontally irregular structures under bi-directional ground motion is assessed under both scaled and seed records in the elastic range. Spectral matching, within limits, of both the horizontal components of real records to a single hazard spectrum is observed to adequately predict the amplification in response due to asymmetry (at least for the records and target spectra relevant to soil class D). Further, such scaling effectively reduces the variability in predicted magnification from one ground motion to other. Dynamic amplification factors recommended in international codes to apply in equivalent static design of asymmetric systems are shown to be deficient.

Application of Mixed Equivalent Solid and Explicit Hole Models to Analysis of Thick Perforated Plates

2008 ◽  
Author(s):  
E. Josserand ◽  
F. Billon
Keyword(s):  
Thermal Gradient ◽  
Nuclear Power ◽  
Power Plants ◽  
Side Surface ◽  
Element Model ◽  
Fatigue Analysis ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Geometrical Effects ◽  
Load Types

Confronted with the problem of how to conduct a complete fatigue analysis of the Tube Plate (TP) of Tubular and Shell Heat Exchangers and particularly of the Steam Generators equipping nuclear power plants of the Pressurized Water Reactor type (PWR), analysts have developed a method to analyse stress in perforated flat and thick Tube Plates with square penetration (crate) patterns, and in particular to analyse several specific zones such as the Interface Zones and various Effects, such as the Secondary (or Shell) Thermal Gradient Effect (STG Effect), the Thermal Gradient in the No-Tube Lane Effect (TGL Effect) and their interactions. The benefit of the approach is that it enables to analyze mechanical and thermal stress calculated using a full 3D Finite Element model incorporating an equivalent solid and the different Interface Zones, and allowing simulating the specific Thermo-Mechanical Effects. The Interface Zones (IZs) are those between the perforated and non-perforated area, the STG Effect is due to the strong gradient near the Secondary (or Shell) Side surface, the TGL Effect is produced by a temperature gradient across the No-Tube Lane. The method used for the fatigue analysis is based on a “Partitioning Stress Method” by means of which the stress induced by the various load types — mechanical loads, global thermal loads, local thermal effects (STG and TGL Effects), and local geometrical effects (IZs) — are first treated separately and then recombined with their appropriate Stress Multiplier Functions.

Selection of the Test Specimens for Seismic Tests of Air-Operated Valve Actuators for Nuclear Power Plants

2019 ◽  
Author(s):  
Nobuo Kojima ◽  
Yoshitaka Tsutsumi ◽  
Yoshinao Matsubara ◽  
Koji Nishino ◽  
Yasuyuki Ito ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Ground Motions ◽  
Test Results ◽  
Earthquake Ground Motions ◽  
Dynamic Function ◽  
Design Earthquake ◽  
Seismic Tests ◽  
Selection Of

Abstract The soundness for the function of air-operated valves in nuclear power plants during earthquake has been investigated via seismic test results and so forth. Since the seismic response acceleration has increased more and more with a recent reassessment of design earthquake ground motions conducted according to the revised Japanese nuclear safety regulation, it is necessary to evaluate the soundness for the function of various valves subject to large acceleration beyond design basis. The air-operated valves currently installed in the nuclear power plants in Japan play the important roles in the sever accident events. In this study, we classified them based on the valve type, manufactures and the previous test results. Furthermore, we proposed the strategy for evaluating the seismic-proof and the seismic test condition for examining the soundness of the dynamic function. Here, the dynamic function is defined as the function required under and after earthquakes.

FE Simulation of Welding Residual Stresses in Reactor Vessel Head Penetrations

2009 ◽  
Author(s):  
Anne Teughels ◽  
Christian Malekian
Keyword(s):  
Residual Stresses ◽  
Nuclear Power ◽  
Power Plants ◽  
Element Model ◽  
Mechanical Analysis ◽  
Alloy 600 ◽  
Finite Elements Analysis ◽  
Pressurized Water ◽  
Water Reactors ◽  
Set Up

The penetrations in the early Pressurized Water Reactors Vessels are characterized by Alloy 600 tubes, welded by Alloy 182/82. The Alloy 600 tubes have been shown to be susceptible to PWSCC (Primary Water Stress Corrosion Cracking) which may lead to crack forming. The cracking mechanism is driven mainly by the welding residual stresses and, in a second place, by the operational stresses in the weld region. It is therefore of big interest to quantify the weld residual stresses correctly. In order to determine the welding residual stresses, the weld procedure is simulated numerically by finite elements analysis. In the article, central as well as eccentric sidehill nozzles on the vessel head are analyzed. For the former a 2-dimensional axisymmetrical finite element model is used, whereas for the latter a 3-dimensional model is set up. A nonlinear transient thermo-mechanical analysis is performed, which is preceded by a transient thermal analysis simulating the heating during the multipass welding. Weld beads are deposited “all-at-once”. Different positions on the vessel head are compared and the influence of the sidehill effect is illustrated. The methodology is applied to the reactor vessels of the Belgian nuclear power plants by Tractebel Engineering (Belgium). The results are compared with literature. The global approach in both cases is very similar but is applied to different configurations, specific for each plant.

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