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At least 415 records · Page 23

Seismic energy data analysis of Merapi volcano to test the eruption time prediction using materials failure forecast method (FFM)

The test of eruption time prediction is an effort to prepare volcanic disaster mitigation, especially in the volcano’s inhabited slope area, such as Merapi Volcano. The test can be conducted by observing the increase of volcanic activity, such as seismicity degree, deformation and SO2 gas emission. One of methods that can be used to predict the time of eruption is Materials Failure Forecast Method (FFM). Materials Failure Forecast Method (FFM) is a predictive method to determine the time of volcanic eruption which was introduced by Voight (1988). This method requires an increase in the rate of change, or acceleration of the observed volcanic activity parameters. The parameter used in this study is the seismic energy value of Merapi Volcano from 1990 – 2012. The data was plotted in form of graphs of seismic energy rate inverse versus time with FFM graphical technique approach uses simple linear regression. The data quality control used to increase the time precision employs the data correlation coefficient value of the seismic energy rate inverse versus time. From the results of graph analysis, the precision of prediction time toward the real time of eruption vary between −2.86 up to 5.49 days.

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Seismic anisotropy, dominant slip systems and phase transitions in the lowermost mantle

SUMMARY The presence of seismic anisotropy at the base of the Earth's mantle is well established, but there is no consensus on the deformation mechanisms in lower mantle minerals that could explain it. Strong anisotropy in magnesium post-perovskite (pPv) has been invoked, but different studies disagree on the dominant slip systems at play. Here, we aim to further constrain this by implementing the most recent results from atomistic models and high-pressure deformation experiments, coupled with a realistic composition and a 3-D geodynamic model, to compare the resulting deformation-induced anisotropy with seismic observations of the lowermost mantle. We account for forward and reverse phase transitions from bridgmanite (Pv) to pPv. We find that pPv with either dominant (001) or (010) slip can both explain the seismically observed anisotropy in colder regions where downwellings turn to horizontal flow, but only a model with dominant (001) slip matches seismic observations at the root of hotter large-scale upwellings. Allowing for partial melt does not change these conclusions, while it significantly increases the strength of anisotropy and reduces shear and compressional velocities at the base of upwellings.

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A Consensus Equilibrium Approach for 3-D Land Seismic Shots Recovery

Physical and budget constraints often result in inadequate sampling for accurate subsurface imaging. Preprocessing approaches, such as missing trace interpolation, are typically employed to enhance seismic data in such cases. The compressed sensing (CS) framework has been applied for modeling missing seismic data, which is estimated by sparsity-based computational algorithms. While existing work mainly focuses on recovering missing traces resulting from receiver subsampling, source subsampling has greater economical advantages, as sources are more expensive than receivers. Moreover, stronger image models different from sparsity have not been explored for source recovery. This work presents a consensus equilibrium (CE) approach to recover missing seismic shots, which enables to incorporate various regularization operators modeling different data priors. Here, simulation results from a real 3-D land seismic dataset demonstrate that the CE approach provides more accurate estimations of the linear and hyperbolic events in the recovered shots, compared with pure sparsity-based reconstructions.

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Preliminary Nuclear Containment Vessel Modeling for Multi-Hazard Probabilistic Risk Assessment under Seismic Hazards and Concrete Degradation

The current practice for natural phenomena hazards (NPH) risk assessment of nuclear facilities is to compute the risk for each hazard independently and then compound the total risk as a combination of single hazard risks. This state of practice does not consider correlations between hazards and the cascading impacts to structures, systems, and components (SSCs), and could thus underestimate the NPH risk or overestimate the nuclear facility safety. Events such as the Fukushima Daiichi accident have highlighted the importance of multi-hazard risk considerations to nuclear power plants (NPPs) that quantify the cascading damage effects to SSCs in the risk models. Moreover, the current fleet of NPPs in the United States is aging; these NPPs are now expected to operate well beyond their initially planned design life. Aging-related deterioration can potentially decrease the capacity of critical structures such as containment vessels to withstand NPH. Such aging considerations may not be adequately accounted for by the current NPH risk assessment guidelines. This paper presents a preliminary modeling and simulation of a representative reinforced concrete containment vessel subjected to seismic mainshock and aftershock considering concrete degradation due to alkali silica reaction. The broader aim is to develop multi-hazard time-dependent fragility functions that could be subsequently used in the probabilistic risk assessment (PRA) model. The multi-hazard component comes into play due to the consideration of damage to the containment vessel under seismic loads and concrete degradation. Consideration of concrete degradation also brings into play the time-dependent nature of the containment vessel response. The response of the containment vessel under varying degrees of concrete degradation to seismic loads is investigated. The results presented are simulated using the Multi-hazard Analysis for STOchastic time-DOmaiN phenomena (MASTODON) software for seismic analysis and the Blackbear software for concrete degradation and damage modeling. Both software are open source and developed within the Multiphysics Object-Oriented Simulation Environment (MOOSE).

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Snake River Plain Geothermal Play Fairway Analysis Project Active Source Seismic Data

This archive contains seismic shot field records for 10 profiles located in Camas Prairie, Idaho. The eight numbered .sgy files were acquired using a seismic land streamer system with an accelerated weight drop source and 72 geophones. These 10-Hz geophones were mounted on base plates and dragged behind the seismic source. Shots were acquired every 4 meters along the length of lines 500West, 550 West, 600West, 700West, 800West, 900West, 200South and 200North. The objective was to map stratigraphy and structures related to geothermal fluid flow in the upper few hundred meters. A readme file is included with descriptions of individual files. The lines names refer to to roads which are numbered relative to the distance from the county seat (the town of Fairfield) along the the main highways. For example, 500 West implies that this north-south street crosses the main road 5 miles to the west of town. The included geologic, topographic, and aerial maps show the labeled seismic lines, while the regional map shows only the line geometry and regional faulting.

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Seismic Survey 2016 Data at Crescent Valley, Nevada

In September 2016, 989 vertical-component seismic instruments were deployed for 75 hours at the Crescent Valley greenfield geothermal play area in Nevada. Data were recorded 12/9/16 - 12/15/16. Data are stored in individual files in one-minute increments in SEGD formats. See the metadata in Crescent Valley Station Locations.sp1, Crescent Valley Observer Logs.xls, and the attached Metadata link for details about the seismic station locations, seismic data logger specifications, instrumentation specifications, descriptions of data, a fracture finding summary, and the final report for the 2016 seismic survey done in Crescent Valley, Nevada. Note that no discrete events were identified, and a 1750m x 2250m x 300m PSET volume of acoustic energy was delivered.

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Utah FORGE 5-2419: Seismicity-Permeability Relationships Probed via Nonlinear Acoustic Imaging - 2024 Annual Workshop Presentation

This is a presentation on Seismicity-Permeability Relationships Probed via Nonlinear Acoustic Imaging by Pennsylvania State University, presented by Derek Elsworth. This video slide presentation discussed controls and acoustic signatures of aseismic through seismic evolution of relocation-stability-permeability on fractures in shear-reactivation as a precursor to, and a key predictor of, seismic moment magnitude of prospective triggered-seismicity. This presentation was featured in the Utah FORGE R&D Annual Workshop on August 13, 2024.

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Advanced Seismic Probabilistic Risk Assessment Demonstration Project Plan

Idaho National Laboratories (INL) has an ongoing research and development (R&D) project to remove excess conservatism from seismic probabilistic risk assessments (SPRA) calculations. These risk calculations should focus on providing best estimate results, and associated insights, for evaluation and decision-making. This report presents a plan for improving our current traditional SPRA process using a seismic event recorded at a nuclear power plant site, with known outcomes, to improve the decision making process. SPRAs are intended to provide best estimates of the various combinations of structural and equipment failures that can lead to a seismic induced core damage event. However, in general this approach has been conservative, and potentially masks other important events (for instance, it was not the seismic motions that caused the Fukushima core melt events, but the tsunami ingress into the facility).

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Proposed Activities to Address Regulatory Gaps and Challenges for Licensing Advanced Reactors Using Seismic Isolation

Over the last decade, particularly since implementation of the certified design regulatory approaches outlined in 10 CFR 52, “Licenses, Certifications, and Approvals for Nuclear Power Plants,” interest has been increasing in the use of seismic isolation (SI) technology to support seismic safety in nuclear facilities. In 2009, the United States (U.S.) Nuclear Regulatory Commission (NRC) initiated research activities to develop new guidance targeted at isolated facilities because SI is being considered for nuclear power plants in the U.S. One product of that research, which was developed around a risk-informed regulatory approach, is a draft NRC NUREG series (NUREG/CR) report that investigates and discusses considerations for use of SI in otherwise traditionally founded large light water reactors (LWRs). A coordinated effort led to new provisions for SI of LWRs in the American Society of Civil Engineers standard ASCE/SEI 4-16, “Seismic Analysis of Safety Related Nuclear Structures.” The risk-informed design philosophy that underpinned development of the technical basis for these documents led to a set of proposed performance objectives and acceptance criteria intended to serve as the foundation for future NRC guidance on the use of SI and related technology. Although the guidance provided in the draft SI NUREG/CR report and ASCE/SEI 4 16 provides a sound basis for further development of nuclear power plant designs incorporating SI, these initial documents were focused on surface-founded or near-surface-founded LWRs and were, necessarily, limited in scope. For example, there is limited information in both the draft NUREG/CR report and ASCE/SEI 4-16 related to nonlinear analysis of soil-structure systems for deeply-embedded reactors, the isolation of components, and the use of vertical isolation systems. Also not included in the draft SI NUREG/CR report are special considerations for licensing of isolated facilities using the certified design approach in 10 CFR 52 and a detailed discussion of seismic probabilistic risk assessments for isolated facilities.

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SSHAC Level 1 Probabilistic Seismic Hazard Analysis for the Idaho National Laboratory

A Probabilistic Seismic Hazard Analysis (PSHA) was completed for the Materials and Fuels Complex (MFC), Naval Reactors Facility (NRF), and the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) (Figure 1-1). The PSHA followed the approaches and procedures appropriate for a Study Level 1 provided in the guidance advanced by the Senior Seismic Hazard Analysis Committee (SSHAC) in U.S. Nuclear Regulatory Commission (NRC) NUREG/CR-6372 and NUREG-2117 (NRC, 1997; 2012a). The SSHAC Level 1 PSHAs for MFC and ATR were conducted as part of the Seismic Risk Assessment (SRA) project (INL Project number 31287) to develop and apply a new-risk informed methodology, respectively. The SSHAC Level 1 PSHA was conducted for NRF to provide guidance on the potential use of a design margin above rock hazard levels. The SRA project is developing a new risk-informed methodology that will provide a systematic approach for evaluating the need for an update of an existing PSHA. The new methodology proposes criteria to be employed at specific analysis, decision, or comparison points in its evaluation process. The first four of seven criteria address changes in inputs and results of the PSHA and are given in U.S. Department of Energy (DOE) Standard, DOE-STD-1020-2012 (DOE, 2012a) and American National Standards Institute/American Nuclear Society (ANSI/ANS) 2.29 (ANS, 2008a). The last three criteria address evaluation of quantitative hazard and risk-focused information of an existing nuclear facility. The seven criteria and decision points are applied to Seismic Design Category (SDC) 3, 4, and 5, which are defined in American Society of Civil Engineers/Structural Engineers Institute (ASCE/SEI) 43-05 (ASCE, 2005). The application of the criteria and decision points could lead to an update or could determine that such update is not necessary.

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SSHAC Level 1 Probabilistic Seismic Hazard Analysis for the Idaho National Laboratory

A Probabilistic Seismic Hazard Analysis (PSHA) was completed for the Materials and Fuels Complex (MFC), Advanced Test Reactor (ATR), and Naval Reactors Facility (NRF) at the Idaho National Laboratory (INL). The PSHA followed the approaches and procedures for Senior Seismic Hazard Analysis Committee (SSHAC) Level 1 study and included a Participatory Peer Review Panel (PPRP) to provide the confident technical basis and mean-centered estimates of the ground motions. A new risk-informed methodology for evaluating the need for an update of an existing PSHA was developed as part of the Seismic Risk Assessment (SRA) project. To develop and implement the new methodology, the SRA project elected to perform two SSHAC Level 1 PSHAs. The first was for the Fuel Manufacturing Facility (FMF), which is classified as a Seismic Design Category (SDC) 3 nuclear facility. The second was for the ATR Complex, which has facilities classified as SDC-4. The new methodology requires defensible estimates of ground motion levels (mean and full distribution of uncertainty) for its criteria and evaluation process. The INL SSHAC Level 1 PSHA demonstrates the use of the PPRP, evaluation and integration through utilization of a small team with multiple roles and responsibilities (four team members and one specialty contractor), and the feasibility of a short duration schedule (10 months). Additionally, a SSHAC Level 1 PSHA was conducted for NRF to provide guidance on the potential use of a design margin above rock hazard levels for the Spent Fuel Handling Recapitalization Project (SFHP) process facility.

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Automated High Power Permanent Borehole Seismic Source Systems for Long-Term Monitoring of Subsurface CO2 Containment and Storage

The geologic storage of CO2 emitted from fixed sources, such as coal or gas power plants, is currently considered one of the prime technologies for short term (~50 year) mitigation of greenhouse gas emissions. The subsurface storage of CO2 for greenhouse gas mitigation will require monitoring to verify that CO2 remains effectively trapped underground, thus permanent seismic sources are needed to provide 24/7 monitoring. GPUSA Inc. has developed and successfully demonstrated numerous prototype vibratory seismic sources with power and performance far beyond any available on the market. The primary objective of this project was to validate in an operational field environment GPUSA’s powerful, low cost, automated borehole seismic source systems for the CO2 storage monitoring application. GPUSA originally proposed the building and testing of two types of permanent sources but ended up building and delivering three types of permanent seismic sources. These sources were delivered to the field test site (Carbon Management Canada’s Containment and Monitoring site near Calgary), however, only two of the systems were able to be tested before the contract ended (despite two contract extensions). The reasons for the delay were primarily weather related both at the US preliminary field test site and Carbon Management Canada site. But in the end, based upon the preliminary field testing in the US and the limited testing that was completed at the Carbon Management Canada site, the results were very impressive, and in some cases far exceeding expectations.

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Seismic Isolation of Major Advanced Reactor Systems for Economic Improvement and Safety Assurance

Advanced reactor concepts currently under development in the United States [e.g., the High-Temperature Gas Reactor (HTGR) of X-Energy and the Molten Chloride Fast Reactor (MCFR) of TerraPower] are striving to improve the economics of nuclear power primarily by using passively and ‘walk-away’ safe technologies in the reactor. The recently published report, ‘Future of Nuclear Energy in a Carbon-Constrained World’ by the Massachusetts Institute of Technology Energy Institute (MIT EI) has shown that a significant contributor to the capital cost of NPPs is the ‘civil works’ i.e., the construction of the balance of plant (BoP: all SSCs except those involved in power generation, e.g., reactor vessel) such as the buildings, containment dome, foundation, etc., which amount to almost half of the overnight capital cost. The report suggests that using advanced construction technologies such as seismic isolation and high-performance concrete to significantly reduce the capital costs of advanced reactors. This report demonstrates the application of two cost-cutting solutions on advanced reactor designs that are currently under development. These solutions include, (1) seismic base isolation, and (2) risk- and cost-based seismic design optimization including seismic isolation of individual components.

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Seismic Observations of the OSIRIS-REx Sample Return Capsule Reentry: Deployment, Signal Characteristics, and Wavefield Phenomenology

Controlled spacecraft reentries from interplanetary trajectories provide rare, well-characterized hypersonic sources for advancing seismoacoustic observation techniques. Here we present seismic observations of the OSIRIS-REx sample return capsule (SRC) reentry on 24 September 2023, recorded by 16 three-component nodal seismometers deployed near Eureka, Nevada, at ground distances of 7–20 km from the capsule trajectory. Air-to-ground coupled signals are detected at all stations, exhibiting impulsive onsets consistent with ballistic shock arrivals from the descending Mach cone. We characterize the seismic wavefield through signal amplitude, period, waveform cross-correlation, and array processing. Signal periods decrease systematically with increasing distance from the trajectory within the airport array, indicating that higher-frequency content becomes more prominent at greater offsets, opposite to expectations from geometric spreading and atmospheric absorption. Seismic array processing identifies frequency-dependent back-azimuth variations whose origin remains unresolved; possible contributing factors include source geometry, scattering by fine-scale layered structure in the stratosphere, and near-surface effects. These observations document a spatially complex seismic wavefield from a well-characterized hypersonic line source and provide constraints for future modeling of atmospheric propagation and air-to-ground coupling.

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Mass Wasting In Planetary Environments: Implications For Seismicity

On Earth, mass wasting events such as rock falls and landslides are well known conse-quences of seismic activity. Through a variety of re-mote sensing techniques, tectonic faults have been pos-itively identified on all four of the inner planets, Earth's Moon, several outer planet satellites, and aster-oids. High-resolution imaging has furthermore ena-bled positive identification of mass wasting events on many of these bodies. On Mars, it has been suggested that fallen boulders may be indicative of pale-omarsquakes. On the Moon, meteor impacts and moonquakes have likewise been suggested as potential triggering mechanisms for mass wasting. Indeed, we know from the Apollo era that the Moon experienc-es a wide variety of seismicity. Seismicity estimates play an important role in creat-ing regional geological characterizations, which are useful not only for understanding a planet's formation and evolution, but also of key importance to site selec-tion for landed missions. Here we investigate the re-gional effects of seismicity in planetary environments with the goal of determining whether surface features such as landslides and boulder trails on the Moon, Mars, and Mercury could be triggered by fault motion. We attempt to quantify the amount of near-source ground shaking necessary to mobilize the mate-rial observed in various instances of mass wasting.

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Spectral Decomposition and Other Seismic Attributes for Gas Hydrate Prospecting

Studying the sediments at the base of gas hydrate stability is ideal for determining the seismic response to gas hydrate saturation. First, assuming gas migration to the shallow section, this area is more likely to have concentrated gas hydrate because it encompasses the zone in which upward moving buoyant gas transitions to form immobile gas hydrate deposits. Second, this zone is interesting because these areas have the potential to show a hydrate filled zone and a gas filled zone within the same sediments. Third, the fundamental measurement within seismic data is impedance contrasts between velocity*density layers. High saturation gas hydrates and free gas inhabit opposite ends of these measurements making the study of this zone ideal for investigating the seismic characteristics of gas hydrate and, hence, the investigation of other seismic attributes that may indicate gas hydrate fill.

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Method advancements for fuel assessments during seismic and LOCA events

The evaluation of fuel assembly structural responses of light-water reactors to seismic and LOCA excitations has received increased attention in the last five years. Real seismic events such as those that affected the Fukushima Daiichi and North Anna plants in 2011 have caused the industry to more closely examine our preparedness for seismic events. Furthermore, the review of design certifications for new plants has raised questions about the methods used to evaluate these events and is leading to revised guidance from regulators (e.g. US NRC Information Notice 2012-09). As a result, the industry is seeing fuel structural design margins based on current methods begin to erode for seismic and LOCA events. This paper will review points for consideration as the industry responds to these changes. To begin, it is worthwhile for the industry to understand the history and the critical thought behind the current methods such that improved criteria and methods can be formulated. This review identifies three known areas of weakness in the current framework for this methodology. First, a broader understanding of spacer grid behavior is needed. Spacer grid behavior in response to impact loads is of paramount importance, but the industry needs to re-frame our characterization of this behavior in order to focus on the actual critical safety function of this component. Secondly, despite guidance from the Standard Review Plan, the effects of irradiation, on spacer grid characteristics, in particular, must be considered. Thirdly, the area of fluid-structure-interaction may be the greatest frontier to conquer in this methodology and may provide our best possibility to recover eroded margins. However, fluid-structure-interactions must be cautiously evaluated and applied with conservatism. (authors)

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Experimental Seismic Response of Scaled Storage Containments under Identical Loading Conditions - 16318

Dry Storage Casks (DSCs) store spent nuclear fuel (SNF), usually at sites contiguous to nuclear power plants known as Independent Spent Fuel Storage Installation (ISFSI). DSCs have been considered as a temporary storage solution, and are usually licensed for 20 years, which can be extended up to an operating periods of 60 years. Recently, however, DSCs have been considered as a potential mid-term solution for hundreds of years. This consideration requires reevaluation of DSC performance under a larger seismic hazard. That leads to larger horizontal and vertical accelerations. This study is a part of a research project evaluating the seismic response of free-standing DSCs under long return period seismic events. This article assess whether the response of free-standing structures under seismic excitation is repeatable. For this purpose, experimental tests were conducted using a six degree-of-freedom (6DOF) shake table. During the experimental tests, several ground motions were repeated multiple times to obtain the dynamic response under identical loading conditions. Scaled casks of four aspect ratios (radius to centroidal height ratio, r/h{sub cg}) were studied: 0.39, 0.43, 0.55 and 0.62. The specimens studied are considered to be 1:2.5 and 1:3.5 scaled model of generic prototype casks. The experimental results show that a small change in initial conditions leads to change in the boundary condition of moving bodies and in combination with acceleration being applied at different frequencies contained within the applied ground motions may lead to a large variation in the response. (authors)

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