Seismic modeling and analysis of a prototype heated nuclear waste storage tunnel, Yucca Mountain, Nevada

We have developed seismic velocity models for the heated rock surrounding a tunnel in Yucca Mountain tuff and compared the results with field data obtained at the Yucca Mountain drift scale test (DST) facility from 1998 to 2002. During that time, the tunnel was heated to replicate the effects of long-term storage of decaying nuclear waste and to study the effects of extreme temperatures on the surrounding rock and groundwater flow. Our velocity models are based on borehole temperature data, thermal models, and laboratory measurements on granite. Comparisons between field and synthetic seismograms show that superheating the rock around the tunnel causes thermally induced variations in P- and S-wave arrival-time separation. Barring out-of-plane reflections, 2D spectral element waveform modeling in the source plane consistently replicates seismic receiver waveforms and classic behavior of pulses reflected from cylinders. Our models constrain the in situ [Formula: see text] velocity/temperature derivative of the tuff to be approximately [Formula: see text] per [Formula: see text]. This velocity change is consistent with thermally induced wavespeed changes in dry rock samples and is lower than expected for water-to-steam conversion in saturated rock. We infer that velocity changes are controlled by thermal expansion and fracturing. Additionally, we have developed an improved method for monitoring tunnel conditions that uses waves diffracted around the tunnel in the region of changing velocity.

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Seismic modeling and analysis of the prototype heated nuclear waste storage tunnel, Yucca Mountain, Nevada

10.1190/1.3059149 ◽

2008 ◽

Author(s):

Steven Smith ◽

Roel Snieder

Keyword(s):

Nuclear Waste ◽

Yucca Mountain ◽

Seismic Modeling ◽

Nuclear Waste Storage ◽

Modeling And Analysis ◽

Waste Storage

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NNWSI Performance Assessment Considerations

MRS Proceedings ◽

10.1557/proc-26-337 ◽

1983 ◽

Vol 26 ◽

Author(s):

L. D. Tyler ◽

R. R. Peters ◽

N. K. Hayden ◽

J. K. Johnstone ◽

S. Sinnock

Keyword(s):

Performance Assessment ◽

Nuclear Waste ◽

Yucca Mountain ◽

Department Of Energy ◽

Nuclear Waste Repository ◽

Nuclear Waste Storage ◽

Human Environment ◽

Assessment Task ◽

Waste Storage ◽

A Site

ABSTRACTThe Nevada Nuclear Waste Storage Investigations (NNWSI) project includes a Performance Assessment task to evaluate the containment and isolation potential for a nuclear waste repository at Yucca Mountain in southern Nevada. This task includes calculations of the rates and concentrations at which radionuclides might be released and transported from the repository and will predict their consequences if they enter the human environment. Among the major tasks required for these calculations will be the development of models for water flow and nuclide transport under unsaturated conditions and in fractured hard rock. The program must also quantify the uncertainties associated with the results of the calculations. The performance assessment will provide evaluations needed for making major decisions as the U. S. Department of Energy seeks a site for a repository. An evaluation will be part of the environmental assessments prepared to accompany the potential nomination of the site. If the Yucca mountain site is selected for characterization and development as a repository, the assessments will be required for an environmental impact statement, a safety analysis report, and other documents.This program has been divided into five tasks. Collectively they will provide the performance assessments needed for the NNWSI Project.

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Design by Analysis of Waste Packages at Yucca Mountain for Impact Loads

Volume 2: Structural Integrity; Safety and Security; Advanced Applications of Nuclear Technology; Balance of Plant for Nuclear Applications ◽

10.1115/icone17-75355 ◽

2009 ◽

Author(s):

Randy J. James ◽

Kenneth Jaquay ◽

Michael J. Anderson

Keyword(s):

Nuclear Waste ◽

Impact Loading ◽

Structural Integrity ◽

Structural Response ◽

Yucca Mountain ◽

Impact Loads ◽

Geologic Repository ◽

Dynamic Simulations ◽

Nuclear Waste Storage ◽

Waste Package

The proposed geologic repository under development at Yucca Mountain, Nevada, will employ multiple shell metallic containers (waste packages) for the disposal of nuclear waste. The waste packages represent a primary engineered barrier for protection and containment of the radioactive waste, and the design of these containers must consider a variety of structural conditions to insure structural integrity. Some of the more challenging conditions for structural integrity involve severe impact loading due to hypothesized event sequences, such as drops or collisions during transport and placement. Due to interactions between the various components leading to complex structural response during an impact sequence, nonlinear explicit dynamic simulations and highly refined models are employed to qualify the design for these severe impact loads. This paper summarizes the Design by Analysis methodologies employed for qualification of waste package design under impact loading and provides several illustrative examples using these methods. Example evaluations include a collision of a waste package by the Transport and Emplacement Vehicle (TEV) and two scenarios due to seismic events, including WP impact within the TEV and impact by falling rock. The examples are intended to illustrate the stringent Design by Analysis methods employed and also highlight the scope of structural conditions included in the design basis for waste packages to be used for proposed nuclear waste storage at Yucca Mountain.

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The Local Earthquake Tomography of Erzurum (Turkey) Geothermal Area

Earth Sciences Research Journal ◽

10.15446/esrj.v23n3.74921 ◽

2019 ◽

Vol 23 (3) ◽

pp. 209-223 ◽

Cited By ~ 2

Author(s):

Caglar Ozer ◽

Mehmet Ozyazicioglu

Keyword(s):

Wave Velocity ◽

Seismic Velocity ◽

Three Dimensional ◽

P Wave ◽

Geothermal Area ◽

S Wave ◽

Velocity Models ◽

Local Earthquake Tomography ◽

P Wave Velocity ◽

Local Earthquake

Erzurum and its surroundings are one of the seismically active and hydrothermal areas in the Eastern part of Turkey. This study is the first approach to characterize the crust by seismic features by using the local earthquake tomography method. The earthquake source location and the three dimensional seismic velocity structures are solved simultaneously by an iterative tomographic algorithm, LOTOS-12. Data from a combined permanent network comprising comprises of 59 seismometers which was installed by Ataturk University-Earthquake Research Center and Earthquake Department of the Disaster and Emergency Management Authority to monitor the seismic activity in the Eastern Anatolia, In this paper, three-dimensional Vp and Vp/Vs characteristics of Erzurum geothermal area were investigated down to 30 km by using 1685 well-located earthquakes with 29.894 arrival times, consisting of 17.298 P- wave and 12.596 S- wave arrivals. We develop new high-resolution depth-cross sections through Erzurum and its surroundings to provide the subsurface geological structure of seismogenic layers and geothermal areas. We applied various size horizontal and vertical checkerboard resolution tests to determine the quality of our inversion process. The basin models are traceable down to 3 km depth, in terms of P-wave velocity models. The higher P-wave velocity areas in surface layers are related to the metamorphic and magmatic compact materials. We report that the low Vp and high Vp/Vs values are observed in Yedisu, Kaynarpinar, Askale, Cimenozu, Kaplica, Ovacik, Yigitler, E part of Icmeler, Koprukoy, Uzunahmet, Budakli, Soylemez, Koprukoy, Gunduzu, Karayazi, Icmesu, E part of Horasan and Kaynak regions indicated geothermal reservoir.

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Ambient lower mantle structure and composition inferred from seismic tomography, convection models, and geochemistry.

10.5194/egusphere-egu2020-11806 ◽

2020 ◽

Author(s):

Grace E. Shephard ◽

John Hernlund ◽

Christine Houser ◽

Reidar Trønnes ◽

Fabio Crameri

Keyword(s):

Lower Mantle ◽

Subduction Zones ◽

Large Scale ◽

Seismic Velocity ◽

Seismic Signal ◽

High Viscosity ◽

S Wave ◽

Velocity Models ◽

Reference Velocity ◽

Seismic Anomalies

<p>The lower mantle can be grouped into high, low, and average (i.e., ambient) seismic velocity domains at each depth, based on the amplitude and polarity of wavespeed perturbations (% &#948;lnVs, % &#948;lnVp). Many studies focus on elucidating the thermo-chemical and structural origins of fast and slow domains, in particular. Subducted slabs are associated with fast seismic anomalies throughout the mantle, and reconstructed palaeo-positions of Cenozoic to Mesozoic subduction zones agrees with seismically imaged deep slabs. Conversely, slow wavespeed domains account for the two antipodal LLSVPs in the lowermost mantle, which are potentially long-lived features, as well as rising hot mantle above the LLSVPs and discrete mantle plumes. However, low-amplitude wavespeeds (close to the reference velocity models) are often overlooked By comparing multiple P- and S-wave tomographic models individually, and through &#8220;vote maps&#8221;, we reveal the depth-dependent characteristics and the geometry of ambient structures, and compare them to numerical convection models. The ambient velocity domains may contain early refractory and bridgmantic mantle with elevated Si/(Mg+Fe) and Mg/Fe ratios (BEAMS; bridgmanite-enriched mantle structures). They could have formed by early basal magma ocean (BMO) fractionation during a period of core-BMO exchange of SiO<sub>2</sub> (from core to BMO) and FeO (from BMO to core), or represent cumulates of BMO crystallization with bridgmanite as the liquidus phase. The high viscosity of bridgmanitic material may promote its convective aggregation and stabilise the large-scale, degree-2 convection pattern. Despite its high viscosity, bridgmanitic material, representing a primitive and refractory reservoir for primordial-like He and Ne components, might be entrained in vigorous, deep-rooted plumes. The restriction of a weak seismic signal, ascribed to iron spin-pairing in ferropericlase, to the fast and slow domains, supports the notion that the ambient lower mantle domains are bridgmanitic.</p>

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Recent advances in rock physics

Geophysics ◽

10.1190/1.1441879 ◽

1985 ◽

Vol 50 (12) ◽

pp. 2480-2491 ◽

Cited By ~ 26

Author(s):

David P. Yale

Keyword(s):

Electrical Properties ◽

Seismic Waves ◽

Seismic Velocity ◽

Pore Space ◽

Rock Physics ◽

Rock Properties ◽

Bright Spot ◽

Geometrical Parameters ◽

S Wave ◽

Velocity Models

The need to extract more information about the subsurface from geophysical and petrophysical measurements has led to a great interest in the study of the effect of rock and fluid properties on geophysical and petrophysical measurements. Rock physics research in the last few years has been concerned with studying the effect of lithology, fluids, pore geometry, and fractures on velocity; the mechanisms of attenuation of seismic waves; the effect of anisotropy; and the electrical and dielectric properties of rocks. Understanding the interrelationships between rock properties and their expression in geophysical and petrophysical data is necessary to integrate geophysical, petrophysical, and engineering data for the enhanced exploration and characterization of petroleum reservoirs. The use of amplitude offsets, S‐wave seismic data, and full‐waveform sonic data will help in the discrimination of lithology. The effect of in situ temperatures and pressures must be taken into account, especially in fractured and unconsolidated reservoirs. Fluids have a strong effect on seismic velocities, through their compressibility, density, and chemical effects on grain and clay surfaces. S‐wave measurements should help in bright spot analysis for gas reservoirs, but theoretical considerations still show that a deep, consolidated reservoir will not have any appreciable impedance contrast due to gas. The attenuation of seismic waves has received a great deal of attention recently. The idea that Q is independent of frequency has been challenged by experimental and theoretical findings of large peaks in attenuation in the low kHz and hundreds of kHz regions. The attenuation is thought to be due to fluid‐flow mechanisms and theories suggest that there may be large attenuation due to small amounts of gas in the pore space even at seismic frequencies. Models of the effect of pores, cracks, and fractures on seismic velocity have also been studied. The thin‐crack velocity models appear to be better suited for representing fractures than pores. The anisotropy of seismic waves, especially the splitting of polarized S‐waves, may be diagnostic of sets of oriented fractures in the crust. The electrical properties of rocks are strongly dependent upon the frequency of the energy and logging is presently being done at various frequencies. The effects of frequency, fluid salinity, clays, and pore‐grain geometry on electrical properties have been studied. Models of porous media have been used extensively to study the electrical and elastic properties of rocks. There has been great interest in extracting geometrical parameters about the rock and pore space directly from microscopic observation. Other models have focused on modeling several different properties to find relationships between rock properties.

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