Simplified methods to estimate mean hazard due to updated ground motion model: Application to nuclear power plants in CEUS

2021 ◽  
pp. 875529302110074
Author(s):  
Mohamed M Talaat ◽  
Andrew Seifried ◽  
Abhinav Anup ◽  
Gregory S Hardy ◽  
John M Richards
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Nuclear Power ◽  
Power Plants ◽  
Site Response ◽  
Motion Model ◽  
Eastern United States ◽  
Logic Tree ◽  
Ground Motion Model ◽  
Good Agreement

Two methods were developed to estimate updated mean seismic hazard for existing probabilistic seismic hazard analyses (PSHAs) due to a change in the ground motion model (GMM). Both methods were used to estimate updated hazard at nuclear power plant (NPP) sites in the Central and Eastern United States (CEUS) for a change from the Electric Power Research Institute (EPRI) 2013 GMM to the Next Generation Attenuation (NGA)-East GMM. These methods present efficient tools to inform decisions on whether to perform a full PSHA revision or other detailed evaluations, especially when a large number of sites must be analyzed. A Simplified Hazard (SiHaz) method was developed to estimate mean hazard explicitly using a reduced PSHA logic tree that incorporates the updated GMM and potential changes in the site response model. An alternative scaling method was independently developed to be applied directly to current CEUS NPP hazard. Both methods were validated using updated PSHA results at several sites. Estimates at 46 NPP sites using both methods showed good agreement for mean annual frequencies of exceedance between 1E-4 and 1E-5/yr.

A Ground-Motion Logic-Tree Scheme for Regional Seismic Hazard Studies

2017 ◽  
Vol 33 (3) ◽  
pp. 837-856 ◽  
Author(s):  
Özkan Kale ◽  
Sinan Akkar
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Motion Prediction ◽  
Motion Model ◽  
Ground Motion Prediction Equations ◽  
Ground Motion Prediction ◽  
Logic Tree ◽  
Ground Motion Model ◽  
The One

We propose a methodology that can be useful to the hazard expert in building ground-motion logic trees to capture the center and range of ground-motion amplitudes. The methodology can be used to identify a logic-tree structure and weighting scheme that prevents the dominancy of a specific ground-motion model. This strategy can be useful for regional probabilistic seismic hazard since logic-trees biased by a specific ground-motion predictive model (GMPE) may cause disparities in the seismic hazard for regions represented by large number of sites with complex seismic features. The methodology first identifies a suit of candidate ground-motion prediction equations that can cover the center, body and range of estimated ground motions. The GMPE set is then used for establishing alternative logic-trees composed of different weighting schemes to identify the one(s) that would not be biased towards a particular GMPE due to its sensitivity to the weights. The proposed methodology utilizes visual and statistical tools to assess the ground motion distributions over large areas that makes it more practical for regional hazard studies.

Seismic risk assessment for the CEUS nuclear power plant fleet based on the NGA-East ground motion model

2021 ◽  
pp. 875529302110246
Author(s):  
Mohamed M Talaat ◽  
Timothy J Graf ◽  
Abhinav Anup ◽  
Gregory S Hardy ◽  
John M Richards
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Nuclear Power ◽  
Assessment Tools ◽  
Specific Information ◽  
Valuable Insight ◽  
Motion Model ◽  
Ground Motion Model

Knowledge of seismic hazard at engineered facilities evolves with the growth in related technical fields. This presents challenges to stability and decision-making concerning safety that require effective assessment tools. Updated mean hazard estimates were developed at nuclear power plant (NPP) sites in Central and Eastern United States (CEUS) using the Next Generation Attenuation (NGA)-East ground motion model (GMM) and the latest available site amplification data. These estimates indicated that seismic hazard increases at several CEUS NPP sites, especially for spectral frequencies below 5 Hz. To assess the safety implications, updated mean seismic core damage frequency (SCDF) estimates were developed for the CEUS NPP fleet using the updated mean hazard estimates and updated plant-level fragilities (PLFs). The PLFs were developed from plant-specific information compiled by the U.S. Nuclear Regulatory Commission (USNRC) and recent seismic probabilistic risk assessments (SPRAs) completed by some NPPs. The SCDF quantification followed a method defined by the USNRC to combine risk contributions from different spectral frequencies. While not intended to provide a precise quantification of risk, such as that provided by a full SPRA, when the results are compared against other estimates using the same approach, this process provides valuable insight into the overall change in risk as the understanding of hazard changes. The assessment indicated no significant change in estimated risk for the majority of the CEUS fleet compared to the 2010 USNRC estimates—about 90% of the fleet risk distribution was lower, equal, or slightly higher. A few NPPs had SCDF estimates significantly larger than the 2010 estimates. The SCDF increases at these few NPPs have larger contributions from updated PLFs than updated hazard estimates. The majority of these NPPs have recently completed detailed SPRAs and have tools to develop more accurate estimates of the updated risk than can be achieved in this fleet-level study.

scholarly journals A ground motion logic tree for seismic hazard analysis in the stable cratonic region of Europe: regionalisation, model selection and development of a scaled backbone approach

2020 ◽  
Vol 18 (14) ◽  
pp. 6119-6148
Author(s):  
Graeme Weatherill ◽  
Fabrice Cotton
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Epistemic Uncertainty ◽  
Hazard Analysis ◽  
Seismic Hazard Analysis ◽  
Eastern United States ◽  
Logic Tree ◽  
Short Period ◽  
Northeastern Europe

Abstract Regions of low seismicity present a particular challenge for probabilistic seismic hazard analysis when identifying suitable ground motion models (GMMs) and quantifying their epistemic uncertainty. The 2020 European Seismic Hazard Model adopts a scaled backbone approach to characterise this uncertainty for shallow seismicity in Europe, incorporating region-to-region source and attenuation variability based on European strong motion data. This approach, however, may not be suited to stable cratonic region of northeastern Europe (encompassing Finland, Sweden and the Baltic countries), where exploration of various global geophysical datasets reveals that its crustal properties are distinctly different from the rest of Europe, and are instead more closely represented by those of the Central and Eastern United States. Building upon the suite of models developed by the recent NGA East project, we construct a new scaled backbone ground motion model and calibrate its corresponding epistemic uncertainties. The resulting logic tree is shown to provide comparable hazard outcomes to the epistemic uncertainty modelling strategy adopted for the Eastern United States, despite the different approaches taken. Comparison with previous GMM selections for northeastern Europe, however, highlights key differences in short period accelerations resulting from new assumptions regarding the characteristics of the reference rock and its influence on site amplification.

Probabilistic Seismic Hazard Analysis Based on Arias Intensity in the North–South Seismic Belt of China

2021 ◽  
Author(s):  
Li Xuejing ◽  
Weijin Xu ◽  
Mengtan Gao
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Hazard Analysis ◽  
Seismic Hazard Analysis ◽  
Probabilistic Seismic Hazard ◽  
Motion Model ◽  
Seismic Belt ◽  
Arias Intensity ◽  
The North ◽  
Ground Motion Model

ABSTRACT Arias intensity (IA), as an important seismic parameter, which contains the information of amplitude, frequencies, and duration of ground motion, plays a crucial role in characterizing seismic hazard such as earthquake-induced landslides. In this article, we conducted probabilistic seismic hazard analysis (PSHA) based on IA in China’s north–south seismic belt. We adopted the seismic sources and seismicity parameters used in the fifth generation of the Seismic Ground Motion Parameter Zoning Map of China, and two ground-motion model of IA. The results show that the values of IA are greater than 0.11 m/s in most regions of the north–south seismic belt. The provincial capital cities and most prefecture-level cities in the seismic zone are located in the region with IA-values greater than 0.32 m/s. The values of IA are above 0.54 m/s in the region around the main fault zone. This means that the north–south seismic belt is prone to extremely high-seismic hazard, particularly earthquake-induced landslides. Therefore, it is important to strengthen the evaluation and prevention of earthquake-induced landslides in this area. As we have found significant differences in the values of IA calculated from different ground-motion model, it is necessary to study the ground-motion model of IA for the western geological environment of China. In addition, the PSHA based on IA gives more consideration to the influence of large earthquakes than that based on peak ground acceleration. Therefore, IA plays an important role in seismic design of major engineering projects. The results of this article are of great scientific significance for understanding the seismic hazard of the north–south seismic belt.

Time-dependent seismic hazard and risk due to wastewater injection in Oklahoma

2021 ◽  
pp. 875529302098802
Author(s):  
Iason Grigoratos ◽  
Paolo Bazzurro ◽  
Ellen Rathje ◽  
Alexandros Savvaidis
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Seismic Risk ◽  
Risk Model ◽  
Time Dependent ◽  
Economic Losses ◽  
Motion Model ◽  
Seismicity Rate ◽  
Ground Motion Model ◽  
Seismicity Rates

In the past decade, Oklahoma has experienced unprecedented seismicity rates, following an increase in the volumes of wastewater that are being disposed underground. In this article, we perform a probabilistic assessment of the time-dependent seismic hazard in Oklahoma and incorporate these results into an integrated seismic risk model to assess the evolution of the statewide economic losses, including a conservative forecast through 2030. Our risk model employs an injection-driven earthquake rate model, a region-specific ground motion model, a recent Vs30 map, HAZUS exposure data and updated vulnerability curves for both structural and nonstructural elements, and contents. The calculations are performed using a stochastic Monte Carlo–based approach implemented in the OpenQuake engine. The resulting seismic hazard maps illustrate the incompatibility of the regional seismic provisions with the current seismicity. In 2015, in particular, the induced seismic hazard in several places in Oklahoma was higher than along the San Andreas fault. During the peak of seismicity in 2015, the seismic risk was 275 times higher than the background level, with the vast majority of losses originating from damages to nonstructural elements and contents. Our direct economic loss estimates are in reasonable agreement with the paid insurance claims, but show significant sensitivity to the ground motion model selection. The proposed risk model, with possible regular updates on the seismicity rate forecast, can help stakeholders define acceptable production levels.

A procedure to develop a backbone ground-motion model: A case study for its implementation

2021 ◽  
pp. 875529302110145
Author(s):  
Sinan Akkar ◽  
Özkan Kale ◽  
M Abdullah Sandıkkaya ◽  
Emrah Yenier
Keyword(s):  
Normal Distribution ◽  
Ground Motion ◽  
Epistemic Uncertainty ◽  
Motion Model ◽  
Logic Tree ◽  
Ground Motion Model ◽  
Stable Continental Region ◽  
Trivariate Normal ◽  
Motion Characterization

The backbone modeling in ground-motion characterization (GMC) is a useful methodology to describe the epistemic uncertainty in median ground-motion predictions. The approach uses a backbone ground-motion model (GMM) and populates the GMC logic tree with the scaled and/or adjusted versions of the backbone GMM to capture the epistemic uncertainty in median ground motions. The scaling and/or adjustment should represent the specific features and uncertainties involved in source, path, and site effects at the target site. The identification of the backbone model requires different considerations specific to the nature of the ground-motion hazard problem. In this article, we present a scaled backbone modeling approach that considers the magnitude- and distance-scaling predictors as well as their correlation to address the epistemic uncertainty in median ground-motion predictions. This approach results in a trivariate normal distribution to fully define a range of epistemic uncertainty in a model sample space. The simultaneous consideration of magnitude and distance scaling while defining the epistemic uncertainty and the methodology followed for the simplified representation of trivariate normal distribution in ground-motion logic tree are the two important features in our procedure. We first present the proposed approach that is followed by a case study for Central and Eastern North America (CENA) stable continental region. The case study discusses the underlying assumptions and limitations of the proposed approach.

Ground Motion Model for the Vertical-to-Horizontal (V/H) Ratios of PGA, PGV, and Response Spectra

2016 ◽  
Vol 32 (2) ◽  
pp. 951-978 ◽  
Author(s):  
Yousef Bozorgnia ◽  
Kenneth W. Campbell
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Hanging Wall ◽  
Strong Dependence ◽  
Response Spectra ◽  
Peak Ground Velocity ◽  
Motion Model ◽  
Fault Rupture ◽  
Ground Acceleration ◽  
Ground Motion Model

We present a ground motion model (GMM) for the vertical-to-horizontal (V/H) ratios of peak ground acceleration, peak ground velocity, and 5%-damped pseudo-acceleration response spectra at periods ranging from 0.01 s to 10 s. The V/H GMM includes formulations for the median V/H ratio and for the aleatory within-event, between-event, and total standard deviations. The V/H model is based on the GMMs we have developed for the vertical and “average” horizontal components of ground motion using a mathematical formation that accounts for the correlation between these two components. We validated the V/H model against the NGA-West2 empirical database. We consider our V/H model to be valid for worldwide shallow crustal earthquakes in active tectonic regions for moment magnitudes ranging from 3.3 to 8.5, depending on the style of faulting, and for fault rupture distances ranging from 0 km to 300 km. Our V/H model incorporates period-dependent effects of magnitude saturation, style of faulting, hypocentral depth, fault-rupture dip, geometric attenuation, regionally dependent anelastic attenuation and site response, hanging-wall geometry, and magnitude-dependent between-event and within-event aleatory variabilities. The V/H ratios predicted from the model show a strong dependence on spectral period and site response.

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