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Fracture Characteristics in a Disposal Pit on Mesita del Buey, Los Alamos National Laboratory

Description: The characteristics of fractures in unit 2 of the Tshirege Member of the Bandelier Tuff were documented in Pit 39, a newly excavated 13.7 m deep disposal pit at Material Disposal Area G on Mesita del Buey. The average spacing between fractures is about 1.0 to 1.3 m, the average fracture aperture is about 3 to 5 mm, and the average fracture dip is about 76o to 77o. Fracture spacing and dip in Pit 39 are generally consistent with that reported from other fracture studies on the Pajarito Plateau, although the fracture apertures in Pit 39 are less than reported elsewhere. Measured fracture orientations are strongly affected by biases imparted by the orientations of the pit walls, which, combined with a small data set, make identification of potential preferred orientations dlfflcult. The most prominent fracture orientations observed in Pit 39, about E-W and N20E, are often not well represented elsewhere on the Pajarito Plateau. Fracture fills contain smectite to about 3 m depth, and calcite and opal may occur at all depths, principally associated with roots or root fossils (rhizoliths). Roots of pifion pine extend in fractures to the bottom of the pit along the north side, perhaps indicating a zone of preferred infiltration of water. Finely powdered tuff with clay-sized particles occurs within a number of fractures and may record abrasive disaggregation associated with small amounts of displacement on minor local faults.
Date: December 1, 1998
Creator: Vaniman, David T. & Reneau, Steven L.
Partner: UNT Libraries Government Documents Department

Structure of the Tshirege Member of the Bandelier Tuff at Mesita del Buey, Technical Area 54, Los Alamos National Laboratory

Description: The geological structure of the Tshirege Member of the Bandelier Tuff at Mesita del Buey, Technical Area 54, was examined using precise surveying of the contact between tuff units Iv and 2 for 3.5 km along the north wall of Pajarito Canyon and 0.6 km along the north wall of a tributary to Caiiada del Buey. Estimated structure contours on this contact indicate typical strikes of N40E to N70E along this part of Mesita del Buey, although the apparent stfike of the tuff is E-W at the western part of the survey. Typical dips are 1.OO to 2.0o to the east or southeast, with an estimated maximum dip of 3.2o near the west end of Material Disposal AreaG. Thirty seven faults with vertical displacements of 5 to 65 cm were observedin outcrops along the Pajarito Canyon traverse, and, due to the incomplete exposure of the contact between unit lV and unit 2, many more faults of this magnitude undoubtedly exist. The faults have a wide range in strike and have either down-to-the-west or down-to-the-east components of offset, although about 65% of the observed displacement is down-to-the-west or northwest. The general absence of larger-scale offsets or inflections along the contact between units lV and 2 in areas where the small-scale faults were observed suggests that they are not associated with major fault zones. Instead, these faults may record distributed secondary deformation across the Pajarito Plateau associated with large earthquakes on the main Pajarito fault zone 8 to 11 km to the west, or perhaps earthquakes on other faults in the region. The survey data also suggest that a 150 to 250 m wide zone of greater magnitude faulting is present near the west end of the traverse associated with a horst-and-graben structure displaying about 1.5 to 3.5 m of offset on ...
Date: December 1, 1998
Creator: LaDelfe, Carol; Broxton, David E.; Carney, John S. & Reneau, Steven L.
Partner: UNT Libraries Government Documents Department

Neutron and gamma (density) logging in welded tuff

Description: This Technical Implementation Procedure (TIP) describes the field operation, and the management of data records pertaining to neutron logging and density logging in welded tuff. This procedure applies to all borehole surveys performed in support of Engineered Barrier System Field Tests (EBSFI� ), including the Earge Block Tests (LBT) and Initial Engineered Barrier System Field Tests (IEBSFT) - WBS The purpose of this TIP is to provide guidelines so that other equally trained and qualified personnel can understand how the work is performed or how to repeat the work if needed. The work will be documented by the use of Scientific Notebooks (SNs) as discussed in 033-YMP-QP 3.4. The TIP will provide a set of guidelines which the scientists will take into account in conducting the mea- surements. The use of this TIP does not imply that this is repetitive work that does not require profes- sional judgment.
Date: September 12, 1998
Creator: Lin, W
Partner: UNT Libraries Government Documents Department

Results of plug-flow reactor experiments with crushed tuff at 280C and 300C

Description: We report on the results to date for two plug-flow reactor experiments, PFR-11 and PFR-13, designed to simulate reactive transport chemical and physical processes. These experiments provide a physical model of idealized one dimensional plug flow and chemical reaction using deionized water and crushed Topopah Springs Tuff (Tsw2). Data consist of effluent ion concentrations and pH measurements taken at several times during both experiments and limited mineralogical analysis of post-test solid phases for PFR-11.
Date: September 2, 1999
Creator: Dibley, M J; Knauss, K G & Rosenberg, N D
Partner: UNT Libraries Government Documents Department

Determination of mineral abundances in samples from the Exploratory Studies Facility, Yucca Mountain, Nevada, using x-ray diffraction

Description: Tuff samples collected from the Exploratory Studies Facility (ESF) were X-rayed to estimate relative mineral abundances. X-ray analysis was performed on sub-samples of specimens collected from both the Single Heater Test (SHT) and Drift Scale Heater Test (MT) that were used for thermomechanical measurements, as well as samples collected from cores retrieved from boreholes in the Drift Scale Test Area. The abundance of minerals that could affect the behavior of the host rock at repository relevant temperatures is of particular interest. These minerals include cristobalite, which undergoes a phase transition and volume change at elevated temperature (-250 {degree}C), and smectite and clinoptilolite that can dehydrate at elevated temperature with accompanying volume reduction. In addition, the spatial distribution of Si02 polymorphs and secondary minerals may provide evidence for deducing past fluid pathways. The mineral abundances tabulated here include data reported previously in three milestone reports but reanalyzed, as well as previously unreported data.
Date: January 13, 1998
Creator: Roberts, S. & Viani, B.
Partner: UNT Libraries Government Documents Department

Report on laboratory tests of drying and re-wetting of intact rocks from the drift scale and single heater tests

Description: The primary focus of this report is the measurement of moisture retention curves of tuff as a function of temperature for both drying and re-wetting conditions. The report contains descriptions of experimental designs and procedures, data, observation, preliminary analyses, and future work. Knowledge of unsaturated transport properties is critical for understanding the movement of water through the unsaturated zone. Evaluation of the performance of a potential nuclear waste repository also depends on these properties. Moisture retention data are important input of numerical models of moisture movement in unsaturated porous media. Also important is the effect of sample history on the moisture retention curves, and whether or not there is significant hysteresis between wetting and drying measurements. This report addresses initial observations regarding this aspect of the research.
Date: January 1, 1998
Creator: Roberts, J.J.; Carlberg, E.; Pletcher, R. & Lin, W.
Partner: UNT Libraries Government Documents Department

Core flow experiment protocol

Description: This letter report describes the current status of the core flow through apparatus and describes the protocol and test matrix to be followed during the initial experimental stage of radionuclide transport studies in the Integrated Testing task.
Date: December 1, 1997
Creator: Viani, B.E. & Martin, S.I.
Partner: UNT Libraries Government Documents Department

Anisotropic behavior in 0.5m scale blocks of Topopah Spring tuff

Description: Laboratory tests on 0.5 meter scale blocks of Topopah Spring tuff were performed to determine fluid flow and mechanical behavior of samples containing fractures. Results include data for a comprehensive set of flow measurements through a rock sample containing a horizontally oriented fracture at uniaxial stress conditions up to 8 MPa at room temperature. Directional channeling, rather than mean fracture aperture, controls the flow. On the time scale of these experiments, inhibition is negligible.
Date: February 1, 1998
Creator: Blair, S. C. & Costantino, M. S.
Partner: UNT Libraries Government Documents Department

A Review of Degradation Behavior of Container Materials for Disposal of High-Level Nuclear Waste in Tuff and Alternative Repository Environments

Description: Corrosion resistance of materials in aqueous systems is reviewed from the perspective of their suitability as container materials for nuclear waste. A discussion of the chemistry and characterization of repository environments, namely, tuff and alternative environments (shale, limestone, and carbonate), is followed by a description of corrosion mechanisms. In this review, emphasis is placed on localized corrosion (e.g., stress corrosion cracking, crevice corrosion, and pitting) because localized corrosion is difficult to account for in design of components, but it is the life-limiting factor for many metallic and nonmetallic systems.
Date: June 1989
Creator: Maiya, P. S.
Partner: UNT Libraries Government Documents Department

[Evolution of Sedimentary Basins--Uinta and Piceance Basins: Chapters J and K]

Description: From abstract: This is a report on reconnaissance geologic mapping and isotopic dating of tuff beds in the Uinta Basin of Utah that show that Lake Uinta probably persisted into late Eocene time in the area east of Duchesne and Strawberry Reservoir.
Date: 1989
Creator: Bryant, Bruce; Naeser, Charles W.; Marvin, Richard F. & Mehert, H. H.
Partner: UNT Libraries Government Documents Department

Postglacial Volcanic Deposits at Mount Baker, Washington, and Potential Hazards From Future Eruptions

Description: Abstract: Eruptions and other geologic events at Mount Baker during the last 10,000 years have repeatedly affected adjacent areas, especially the valleys that head on the south and east sides of the volcano. Small volumes of tephra were erupted at least four times during the past 10,000 years. Future eruptions like these could cause as much as 35 centimeters of tephra to be deposited at sites 17 kilometers from the volcano, 15 centimeters of tephra to be deposited 29 kilometers from the volcano, and 5 centimeters, 44 kilometers from the volcano. Lava flows were erupted at least twice during the last 10,000 years and moved down two valleys. Future lava flows will not directly endanger people because lava typically moves so slowly that escape is possible. Hot pyroclastic flows evidently occurred during only one period and were confined to the Boulder Creek valley. Such flows can move at speeds of as much as 150 kilometers per hour and can bury valley floors under tens of meters of hot rock debris for at least 15 kilometers from the volcano. Large mudflows, most of which contain hydrothermally altered rock debris, originated at Mount Baker at least eight times during the last 10,000 years. The largest mudflow reached 29 kilometers or more down the valley of the Middle Fork Nooksack River, west of the volcano, about 6,000 years ago. Extensive masses of hydrothermally altered rock that are potentially unstable exist today near the summit of the volcano, especially in the Sherman Crater-Sherman Peak area. Avalanches of this material could be triggered by stream explosions, earthquakes, or eruptions, or may occur because of slow-acting forces or processes that gradually decrease stability. Large avalanches could move downslope at high speed and could grade downvalley into mudflows. Floods caused by rapid melting of snow and ice ...
Date: 1978
Creator: Hyde, Jack H. & Crandell, Dwight Raymond
Partner: UNT Libraries Government Documents Department

Analysis of Fracture in Cores from the Tuff Confining Unit beneath Yucca Flat, Nevada Test Site

Description: The role fractures play in the movement of groundwater through zeolitic tuffs that form the tuff confining unit (TCU) beneath Yucca Flat, Nevada Test Site, is poorly known. This is an important uncertainty, because beneath most of Yucca Flat the TCU lies between the sources of radionuclide contaminants produced by historic underground nuclear testing and the regional carbonate aquifer. To gain a better understanding of the role fractures play in the movement of groundwater and radionuclides through the TCU beneath Yucca Flat, a fracture analysis focusing on hydraulic properties was performed on conventional cores from four vertical exploratory holes in Area 7 of Yucca Flat that fully penetrate the TCU. The results of this study indicate that the TCU is poorly fractured. Fracture density for all fractures is 0.27 fractures per vertical meter of core. For open fractures, or those observed to have some aperture, the density is only 0.06 fractures per vertical meter of core. Open fractures are characterized by apertures ranging from 0.1 to 10 millimeter, and averaging 1.1 millimeter. Aperture typically occurs as small isolated openings along the fracture, accounting for only 10 percent of the fracture volume, the rest being completely healed by secondary minerals. Zeolite is the most common secondary mineral occurring in 48 percent of the fractures observed.
Date: March 1, 2008
Creator: Prothro, Lance
Partner: UNT Libraries Government Documents Department

Deposits of Pre-1980 Pyroclastic Flows and Lahars from Mount St. Helens Volcano, Washington

Description: From introduction: This report describes the character, origin, age, and extent of deposits of pyroclastic flows and lahars that were formed at Mount St. Helens before 1980, and their stratigraphic relations to other rocks and deposits of volcanic and glacial origin.
Date: 1987
Creator: Crandell, Dwight Raymond
Partner: UNT Libraries Government Documents Department

High-pressure mechanical properties of an Area 12, Nevada Test Site tuff

Description: The mechanical properties of tuff from instrument hole UG3, tunnel U12e.06 at the Nevada Test Site have been investigated to 1400 MPa, The shear strength increases from about 5 MHa unconfined to 12 MPa at 300 MPa mean pressure. A brittle-ductile transition was indicated at about 250 MPa. In uniaxial strain, the sample loads to the vicinity of the failure envelope and then is parallel to that envelope up to the highest stresses, 420 MPa. Hydrostatic pressure of 1400 MPa produces about 9% volume compression and 1.3% permanent compaction in this apparently saturated tuff. (auth)
Date: November 19, 1973
Creator: Duba, A.; Abey, A. E. & Heard, H. C.
Partner: UNT Libraries Government Documents Department

Preliminary evaluation of alterant geophysical tomography in welded tuff

Description: The ability of alterant geophysical tomography to delineate flow paths in a welded tuff rock mass has been preliminarily evaluated based on the results of a field experiment. Electromagnetic measurements were made before, during and after a water-based, dye tracer flowed through the rock mass. Alterant geophysical tomographs were generated and compared with independent evidence - borescope logs, neutron logs and dyed rock samples. Anomalies present in the tomograph match the location and orientation of fractures mapped with a borescope. The location of tracer-strained fractures coincides with the location of some image anomalies; other geophysical anomalies exist where tracer-strained fractures were not observed, perhaps due to poor core recovery. Additional drilling to locate stained flow paths and other experiments are planned so that the applicability of the technique can be further evaluated. 7 refs., 5 figs.
Date: February 1, 1985
Creator: Ramirez, A.L. & Daily, W.D.
Partner: UNT Libraries Government Documents Department

Joint orientation and characteristics as observed in a trench excavated near TA-3 and a basement excavated at TA-55

Description: Walls of excavations in the Bandelier Tuff for pipelines and foundations for structures provide excellent areas to determine the orientation (strike and dip) and characteristics of the joints (frequency, width, and type of material filling the joint). Joints or fractures are commonly associated with structural adjustments such as faulting; however, joints formed in the tuff mainly result from the shrinkage of the ash-flow tuff as it cools. The presence of faults can restrict the siting of buildings or structures. In waste disposal operations, open joints can be pathways for the transport of contaminants.
Date: October 1, 1995
Creator: Purtymun, W.D.; Koenig, E.; Morgan, T. & Sagon, E.
Partner: UNT Libraries Government Documents Department

Intracrystalline diffusion in clinoptilolite: Implications for radionuclide isolation

Description: Experiments have been performed to measure the rate of exchange diffusion in the zeolite clinoptilolite (CL) for elements important to radionuclide isolation at Yucca Mountain, NV. Clinoptilolite is one of the major sorptive minerals in the tuffs at Yucca Mountain, and occurs both as a major component in zeolitized units (Calico Hills), and in fractures in non-zeolitized tuffs (Topopah Spring). Field evidence and numerical modeling suggests that the movement of fluids through the tuff rocks adjacent to the potential repository may occur via episodic flow through fractures. Under conditions of rapid fracture flow the effective sorptive capacity of fracture-lining clinoptilolite may be controlled by exchange diffusion rather than exchange equilibrium.
Date: November 16, 1995
Creator: Roberts, S.K.; Viani, B.E. & Phinney, D.
Partner: UNT Libraries Government Documents Department

High-Resolution Aeromagnetic Survey Map of Part of the Southwest Nevada Volcanic Field

Description: A high-resolution aeromagnetic survey was recently flown to collect data for geologic investigations in the Southwest Nevada Volcanic Field. This survey represents a marked improvement over previous (1999) surveys. The survey includes over 860 km{sup 2} covered by nearly 16,000 km of flightline with 60-m spacing and an instrument altitude of 30 m above the ground surface. Features of interest visible in the dataset include magnetic banding in the volcanic tuffs that form the faulted terrain and sharp delineation of Quaternary basalt cinder cones and lava flows. This 1:100,000-scale map includes a shaded-relief map base and a semi-transparent overlay of the aeromagnetic data, with inset maps illustrating (1) comparisons of detail between the 1999 and 2004 datasets, (2) polarity reversal banding in the volcanic tuff ridges, (3) details of the morphology of Quaternary basalt centers enhanced by aeromagnetic data, and (4) use of GIS in planning the survey.
Date: June 21, 2004
Creator: Keating, G.; Prueitt, R. & Cogbill, A.
Partner: UNT Libraries Government Documents Department

Geophysical tomography for imaging water movement in welded tuff

Description: Alterant tomography has been evaluated for its ability to delineate in-situ water flow paths in a fractured welded-tuff rock mass. The evaluation involved a field experiment in which tomographs of electromagnetic attenuation factor (or attenuation rate) at 300 MHZ were made before, during, and after the introduction to the rock of two different water-based tracers: a plain water and dye solution, and salt water and dye. Alterant tomographs were constructed by subtracting, cell by cell, the attenuation factors derived from measurements before each tracer was added to the rock mass from the attenuation factors derived after each tracer was added. The alterant tomographs were compared with other evidence of water movement in the rock: borescope logs of fractures, and postexperiment cores used to locate the dye tracer on the fractured surfaces. These comparisons indicate that alterant tomography is suitable for mapping water flow through fractures and that it may be useful in inferring which of the fractures are hydrologically connected in the image plane. The technique appears to be sensitive enough to delineate flow through a single fracture and to define fractures with a spatial resolution of about 10 cm on an imaging scale of a few meters. 9 refs., 3 figs.
Date: September 1, 1986
Creator: Daily, W. & Ramirez, A.
Partner: UNT Libraries Government Documents Department

Waste package for a repository located in tuff

Description: The development of waste packages for emplacement in a tuff repository has been proceeding during the past year on a broad front. Experimental work has been focused on determination of important package environment parameters and testing the response of waste forms and package materials to the anticipated environment. Conceptual designs have been selected with alternatives to accommodate present uncertainties in the environment and material performance. Computational capabilities are being adapted to provide analyses of anticipated package performance, and plans are being developed for in-situ testing. The waste package activities have been integrated into the overall NNWSI project to assure timely completion consistent with the statutory and regulatory requirements leading to repository site selection around the end of the decade. 7 references.
Date: November 1, 1983
Creator: Ballou, L.B.
Partner: UNT Libraries Government Documents Department

X-ray radiography of fracture flow and matrix imbibition in Topopah Spring Tuff under a thermal gradient

Description: A method of imaging the flow of liquid in fractures and matrix imbibition in tuff using x-ray radiography has been developed and a formulation for the calculation of saturation in the matrix based on x-ray radiography is presented. Experiments were performed using different thermal gradients and hydrostatic heads. The distance that liquid penetrates the boiling region was found to be dependent on hydrostatic head: during the highest-head experiment, liquid water penetrated the entire fracture and continued to pass through the boiling region. For experiments where flow stopped at the boiling region, x-ray images indicate crystal deposition along the fracture. In some cases, when the sample was cooled, fracture flow resumed, and in other cases the fractures were sealed and flow did not continue.
Date: March 1, 1997
Creator: Roberts, J.J., Lin, W.
Partner: UNT Libraries Government Documents Department