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Sample records for canyon tuff para

  1. Distribution of moisture, tritium, and plutonium in the alluvium, aquifer, and underlying tuff in Mortandad Canyon

    International Nuclear Information System (INIS)

    Purtymun, W.D.; Maes, M.N.; Peters, R.

    1985-01-01

    A study of the distribution of moisture, tritium, and plutonium in the Mortandad Canyon aquifer indicates some infiltration of water into the underlying tuff. This infiltration was accompanied by similar movement of tritium. The concentrations of plutonium on the sediments in the aquifer were low when compared with the high concentrations in solution in an ionic complex that does not readily exchange or is adsorbed by clay minerals in the alluvium. 2 references, 4 figures, 2 tables

  2. Preliminary modeling of moisture movement in the tuff beneath Mortandad Canyon, Los Alamos National Laboratory

    International Nuclear Information System (INIS)

    Geddis, A.M.

    1992-01-01

    An area of upper/middle Mortandad Canyon on the Los Alamos National Laboratory is modeled in cross-section. UNSAT2, a finite element model (FEM) is used to predict moisture movement. Hydraulic characteristics of the tuff are described by van Genuchten parameters determined from laboratory tests on cores taken from a borehole within the cross-section. Material properties are distributed horizontal planar in space to cover the solution domain with required initial conditions. An estimate of seepage flux from a thin perched alluvial aquifer into the upper surface of the tuff is taken from a lumped parameter model. Moisture redistribution for a ponded boundary condition and a larger flux is investigated. A composite simulation using material properties from two separate coreholes is also evaluated

  3. Geochemical and Pb, Sr, and O isotopic study of the Tiva Canyon Tuff and Topopah Spring Tuff, Yucca Mountain, Nye County, Nevada

    International Nuclear Information System (INIS)

    Neymark, L.A.; Marshall, B.D.; Kwak, L.M.; Futa, Kiyoto; Mahan, S.A.

    1995-01-01

    Yucca Mountain is currently being studied as a potential site for an underground repository for high-level radioactive waste. One aspect of the site characterization studies is an evaluation o the resource potential at Yucca Mountain. Geochemical and isotopic signatures of past alteration of the welded tuffs that underlie Yucca Mountain provide a means of assessing the probability of hydrothermal ore deposits being present within Yucca Mountain. In this preliminary report, geochemical and isotopic measurements of altered Tiva Canyon Tuff and Topopah Spring Tuff collected from fault zones exposed on the east flank of Yucca Mountain and from one drill core are compared to their unaltered equivalents sampled both in outcrop and drill core. The geochemistry and isotopic compositions of unaltered Tiva Canyon Tuff and Topopah Spring Tuff (high-silica rhyolite portions) are fairly uniform; these data provide a good baseline for comparisons with the altered samples. Geochemical analyses indicate that the brecciated tuffs are characterized by addition of calcium carbonate and opaline silica; this resulted in additions of calcium and strontium,increases in oxygen-18 content, and some redistribution of trace elements. After leaching the samples to remove authigenic carbonate, no differences in strontium or lead isotope compositions between altered and unaltered sections were observed. These data show that although localized alteration of the tuffs has occurred and affected their geochemistry, there is no indication of additions of exotic components. The lack of evidence for exotic strontium and lead in the most severely altered tuff samples at Yucca Mountain strongly implies a similar lack of exotic base or precious metals

  4. Petrology and geochemistry of the Grouse Canyon Member of the Belted Range Tuff, Rock-Mechanics Drift, U12g Tunnel, Nevada Test Site

    International Nuclear Information System (INIS)

    Connolly, J.R.; Mansker, W.L.; Hicks, R.; Allen, C.C.; Husler, J.; Keil, K.; Lappin, A.R.

    1983-04-01

    G-Tunnel at Nevada Test Site (NTS) is the site of thermal and thermomechanical experiments examining the feasibility of emplacing heat-producing nuclear wastes in silicic tuffs. This report describes the general stratigraphy, mineralogy, and bulk chemistry of welded portions of the Grouse Canyon Member of the Belted Range Tuff, the unit in which most of these experiments will be performed. The geologic characteristics of the Grouse Canyon Member are compared with those of the Topopah Spring Member of the Paintbrush Tuff, presently the preferred horizon for an actual waste repository at Yucca Mountain, near the southwest boundary of Nevada Test Site. This comparison suggests that test results obtained in welded tuff from G-Tunnel are applicable, with limitations, to evaluation of the Topopah Spring Member at Yucca Mountain

  5. Geochemistry of core samples of the Tiva Canyon Tuff from drill hole UE-25 NRG number-sign 3, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Peterman, Z.E.; Futa, K.

    1996-01-01

    The Tiva Canyon Tuff of Miocene age is composed of crystal-poor, high-silica rhyolite overlain by a crystal-rich zone that is gradational in composition from high-silica rhyolite to quartz latite. Each of these zones is divided into subzones that have distinctive physical, mineralogical, and geochemical features.Accurate identification of these subzones and their contacts is essential for detailed mapping and correlation both at the surface and in the subsurface in drill holes and in the exploratory studies facility (ESF). This report presents analyses of potassium (K), calcium (Ca), titanium (Ti), rubidium (Rb), strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), barium (Ba), lanthanum (La), and cerium (Ce) in core samples of the Tiva Canyon Tuff from drill hole UE-25 NRG number-sign 3. The concentrations of most of these elements are remarkably constant throughout the high-silica rhyolite, but at its upper contact with the crystal-rich zone, Ti, Zr, Ba, Ca, Sr, La, Ce, and K begin to increase progressively through the crystal-rich zone. In contrast, Rb and Nb decrease, and Y remains essentially constant. Initial 87 Sr/ 86 Sr ratios are relatively uniform in the high-silica rhyolite with a mean value of 0.7117, whereas initial 87 Sr/ 86 Sr ratios decrease upward in the quartz latite to values as low as 0.7090

  6. The effect of saturation of the mechanical properties of tuff at Yucca Mountain

    International Nuclear Information System (INIS)

    Karakouzian, M.; Hudyma, N.

    1996-01-01

    This study investigates the effect of saturation on the mechanical properties, namely compressive strength and Young's Modulus, of Tiva Canyon welded tuff and Topopah Spring welded tuff from the Nevada Test Site. Unconfined compression tests on air dried and saturated specimens show that saturation lowers both the average compressive strength and the average Young's Modulus of Topopah Spring and Tiva Canyon tuff specimens. Saturation increases the variability of the mechanical properties of Topopah Spring tuff and the variability of the compressive strength of Tiva Canyon tuff

  7. Frictional properties of jointed welded tuff

    International Nuclear Information System (INIS)

    Teufel, L.W.

    1981-07-01

    The results of the experiments on simulated joints in welded tuff from the Grouse Canyon Member of the Belted Range Tuff warrant the following conclusions: (1) The coefficient of friction of the joints is independent of normal stress at a given sliding velocity. (2) The coefficient of friction increases with both increasing time of stationary contact and decreasing sliding velocity. (3) Time and velocity dependence of friction is due to an increase in the real area of contact on the sliding surface, caused by asperity creep. (4) Joints in water-saturated tuff show a greater time and velocity dependence of friction than those in dehydrated tuff. (5) The enhanced time and velocity dependence of friction with water saturation is a result of increased creep at asperity contacts, which is in turn due to a reduction in the surface indentation hardness by hydrolytic weakening and/or stress corrosion cracking

  8. Air-injection testing in vertical boreholes in welded and nonwelded Tuff, Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    LeCain, G.D.

    1997-12-31

    Air-injection tests, by use of straddle packers, were done in four vertical boreholes (UE-25 UZ-No.16, USW SD-12, USW NRG-6, and USW NRG-7a) at Yucca Mountain, Nevada. The geologic units tested were the Tiva Canyon Tuff, nonwelded tuffs of the Paintbrush Group, Topopah Spring Tuff, and Calico Hills Formation. Air-injection permeability values of the Tiva Canyon Tuff ranged from 0.3 x 10{sup -12} to 54.0 x 10{sup -12} m{sup 2}(square meter). Air-injection permeability values of the Paintbrush nonwelded tuff ranged from 0.12 x 10{sup -12} to 3.0 x 10{sup -12} m{sup 2}. Air-injection permeability values of the Topopah Spring Tuff ranged from 0.02 x 10{sup -12} to 33.0 x 10{sup -12} m{sup 2}. The air-injection permeability value of the only Calico Hills Formation interval tested was 0.025 x 10{sup -12} m{sup 2}. The shallow test intervals of the Tiva Canyon Tuff had the highest air-injection permeability values. Variograms of the air-injection permeability values of the Topopah Spring Tuff show a hole effect; an initial increase in the variogram values is followed by a decrease. The hole effect is due to the decrease in permeability with depth identified in several geologic zones. The hole effect indicates some structural control of the permeability distribution, possibly associated with the deposition and cooling of the tuff. Analysis of variance indicates that the air-injection permeability values of borehole NRG-7a of the Topopah Spring Tuff are different from the other boreholes; this indicates areal variation in permeability.

  9. Stonewall Mountain Volcanic Center, southern Nevada: Stratigraphic, structural, and facies relations of outflow sheets, near-vent tuffs, and intracaldera units

    Science.gov (United States)

    Weiss, Steven I.; Noble, Donald C.

    1989-05-01

    Directly south and southeast of Stonewall Mountain, Nevada, a depression and north facing caldera scarp were formed during and(or) after eruption of the Spearhead Member of the late Miocene Stonewall Flat Tuff. Abundant large lithic and juvenile blocks are present in the Spearhead Member within 0.5 km of this topographic margin but absent elsewhere in the ash-flow sheet, consistent with eruption from vents in the Stonewall Mountain area. Within about 100,000 years, comendite tuff of the overlying Civet Cat Canyon Member of the Stonewall Flat Tuff buried the depression and associated scarp. The Civet Cat Canyon Member is traceable continuously to the north from an outflow sheet capping northwestern Pahute Mesa, into near-vent tuff on the southeastern flank of Stonewall Mountain. Proximal outflow-sheet tuff locally exhibits strong rheomorphic disruption and is overlain without a cooling break by surge, flow, and fall deposits of trachytic composition. Much of Stonewall Mountain is composed of welded tuff and megabreccia interpreted as intracaldera tuff of the Civet Cat Canyon Member, strongly suggesting that the vent area of the member was largely within Stonewall Mountain. Welded tuff of trachytic composition comprises an important part of the intracaldera Civet Cat Canyon Member, which was intruded by dikes and plugs of trachyte and rhyolite. Juvenile inclusions of basalt dispersed in near-vent facies trachyte tuff provide direct evidence for the high-level involvement of basaltic magma in the evolution of the highly potassic Stonewall Mountain center. Complex discordant compaction foliations and the widespread presence of megabreccia within the intracaldera tuff suggest, following Foley (1978), cauldron subsidence by piecemeal collapse during eruption of the Civet Cat Canyon Member. The elevation of intracaldera tuff and intrusions in Stonewall Mountain above the surrounding ashflow sheet suggests a significant amount of magmatic uplift, perhaps involving the

  10. Diablo Canyon

    International Nuclear Information System (INIS)

    Bindon, F.J.L.

    1986-01-01

    The paper traces the history of Diablo Canyon nuclear power station, California, which took 18 years to reach full-power testing from the planning stage. The major delays during the construction are outlined, as well as the costs of Diablo Canyon. (UK)

  11. Laboratory investigation of constitutive property up-scaling in volcanic tuffs

    International Nuclear Information System (INIS)

    Tidwell, V.C.

    1996-08-01

    One of the critical issues facing the Yucca Mountain site characterization and performance assessment programs is the manner in which property up-scaling is addressed. Property up-scaling becomes an issue whenever heterogeneous media properties are measured at one scale but applied at another. A research program has been established to challenge current understanding of property up-scaling with the aim of developing and testing improved models that describe up-scaling behavior in a quantitative manner. Up-scaling of constitutive rock properties is investigated through physical experimentation involving the collection of suites of gas-permeability data measured over a range of discrete scales. To date, up-scaling studies have been performed on a series of tuff and sandstone (used as experimental controls) blocks. Samples include a welded, anisotropic tuff (Tiva Canyon Member of the Paintbrush Tuff, upper cliff microstratigraphic unit), and a moderately welded tuff (Tiva Canyon Member of the Paintbrush Tuff, Caprock microstratigraphic unit). A massive fluvial sandstone (Berea Sandstone) was also investigated as a means of evaluating the experimental program and to provide a point of comparison for the tuff data. Because unsaturated flow is of prime interest to the Yucca Mountain Program, scoping studies aimed at investigating the up-scaling of hydraulic properties under various saturated conditions were performed to compliment these studies of intrinsic permeability. These studies focused on matrix sorptivity, a constitutive property quantifying the capillarity of a porous medium. 113 refs

  12. Geohydrology of Bandelier Tuff

    International Nuclear Information System (INIS)

    Abeele, M.V.; Wheeler, M.L.; Burton, B.W.

    1981-10-01

    The Los Alamos National Laboratory has been disposing of radioactive wastes since 1944. Environmental studies and monitoring for radioactive contamination started concurrently. In this report, only two mechanisms and rates by which the radionuclides can enter the environment are studied in detail: subsurface transport of radionuclides by migrating water, and diffusion of tritiated water (HTO) in the vapor phase. The report also includes a section concerning the influence of moisture on shear strength and possible resulting subsidences occurring in the pit overburdens. Because subsurface transport of radionuclides is influenced by the hydraulic conductivity and this in turn is regulated by the moisture content of any given material, a study was also undertaken involving precipitation, the most important climatic element influencing the geohydrology of any given area. Further work is in progress to correlate HTO emanation to atmospheric and pedological properties, especially including thermal characteristics of the tuff

  13. Logs and completion data for water and mass balance wells in Mortandad and Ten Site Canyons

    International Nuclear Information System (INIS)

    McLin, S.G.; Koch, R.J.

    1997-10-01

    Twenty-four monitoring wells were drilled and completed in December 1994 as part of a water and mass balance study for the shallow perched aquifer in the Mortandad Canyon alluvium and in the lower part of Ten-Site Canyon. The wells penetrated the alluvium containing the aquifer and were completed into the top of the weathered tuff. Twelve of these wells encountered the Tshirege Member (Cooing Unit 1 g) of the Bandelier Tuff below the canyon alluvium, while ten wells made contact with the Cerro Toledo interval, which lies between the Tshirege and Otowi Members of the Bandelier Tuff. The remaining two wells were completed into the alluvium above the weathered tuff contact. These wells provide access for continuous water level measurement and water sampling. Data from these new wells will be used to determine changes in alluvial aquifer water storage, water quality sampling, and estimation of seepage into the unsaturated Bandelier Tuff below the alluvium. This report documents drilling activities and well completion logs for the water and mass balance study. These wells also provide critical new data for fourteen north-south vertical cross-sections constructed for the canyon alluvium

  14. Magnetic properties and emplacement of the Bishop tuff, California

    Science.gov (United States)

    Palmer, H.C.; MacDonald, W.D.; Gromme, C.S.; Ellwood, B.B.

    1996-01-01

    Anisotropy of magnetic susceptibility (AMS) and characteristic remanence were measured for 45 sites in the 0.76 Ma Bishop tuff, eastern California. Thirty-three sites were sampled in three stratigraphic sections, two in Owens gorge south of Long Valley caldera, and the third in the Adobe lobe north of Long Valley. The remaining 12 sites are widely distributed, but of limited stratigraphic extent. Weakly indurated, highly porous to dense, welded ash-flow tuffs were sampled. Saturation magnetization vs temperature experiments indicate two principal iron oxide phases: low Ti magnetites with 525-570 ??C Curie temperatures, and maghemite with 610??-640??C Curie temperatures. AF demagnetization spectra of isothermal remanent magnetizations are indicative of magnetite/maghemite predominantly in the multidomain to pseudo-single domain size ranges. Remeasurement of AMS after application of saturating direct fields indicates that randomly oriented single-domain grains are also present. The degree of anisotropy is only a few percent, typical of tuffs. The AMS ellipsoids are oblate with Kmin axes normal to subhorizontal foliation and Kmax axes regionally aligned with published source vents. For 12 of 16 locality means, Kmax axes plunge sourceward, confirming previous observations regarding flow sense. Topographic control on flow emplacement is indicated by the distribution of tuff deposits and by flow directions inferred from Kmax axes. Deposition east of the Benton range occurred by flow around the south end of the range and through two gaps (Benton notch and Chidago gap). Flow down Mammoth pass of the Sierra Nevada is also evident. At least some of the Adobe lobe in the northeast flowed around the west end of Glass mountain. Eastward flow directions in the upper Owens gorge and southeast directions in the lower Owens gorge are parallel to the present canyon, suggesting that the present drainage has been established along the pre-Bishop paleodrainage. Characteristic remanence

  15. In-situ tuff water migration/heater experiment: experimental plan

    International Nuclear Information System (INIS)

    Johnstone, J.K.

    1980-08-01

    Tuffs on the Nevada Test Site (NTS) are currently under investigation as a potential isolation medium for heat-producing nuclear wastes. The National Academy of Sciences has concurred in our identification of the potentially large water content (less than or equal to 40 vol %) of tuffs as one of the important issues affecting their suitability for a repository. This Experimental Plan describes an in-situ experiment intended as an initial assessment of water generation/migration in response to a thermal input. The experiment will be conducted in the Grouse Canyon Welded Tuff in Tunnel U12g (G-Tunnel) located in the north-central region of the NTS. While the Grouse Canyon Welded Tuff is not a potential repository medium, it has physical, thermal, and mechanical properties very similar to those tuffs currently under consideration and is accessible at depth (400 m below the surface) in an existing facility. Other goals of the experiment are to support computer-code and instrumentation development, and to measure in-situ thermal properties. The experimental array consists of a central electrical heater, 1.2 m long x 10.2 cm diameter, surrounded by three holes for measuring water-migration behavior, two holes for measuring temperature profiles, one hole for measuring thermally induced stress in the rock, and one hole perpendicular to the heater to measure displacement with a laser. This Experimental Plan describes the experimental objectives, the technical issues, the site, the experimental array, thermal and thermomechanical modeling results, the instrumentation, the data-acquisition system, posttest characterization, and the organizational details

  16. Effect of moisture on tuff stone degradation

    NARCIS (Netherlands)

    Lubelli, B.A.; Nijland, T.G.

    2016-01-01

    Tuff stone elements with a large length/width ratio often suffer damage in the form of cracks parallel to the surface and spalling of the outer layer. The response of tuff to moisture might be a reason for this behaviour. This research aimed at verifying if differential dilation between parts with

  17. Preliminary thermal expansion screening data for tuffs

    International Nuclear Information System (INIS)

    Lappin, A.R.

    1980-03-01

    A major variable in evaluating the potential of silicic tuffs for use in geologic disposal of heat-producing nuclear wastes is thermal expansion. Results of ambient-pressure linear expansion measurements on a group of tuffs that vary treatly in porosity and mineralogy are presente here. Thermal expansion of devitrified welded tuffs is generally linear with increasing temperature and independent of both porosity and heating rate. Mineralogic factors affecting behavior of these tuffs are limited to the presence or absence of cristobalite and altered biotite. The presence of cristobalite results in markedly nonlinear expansion above 200 0 C. If biotite in biotite-hearing rocks alters even slightly to expandable clays, the behavior of these tuffs near the boiling point of water can be dominated by contraction of the expandable phase. Expansion of both high- and low-porosity tuffs containing hydrated silicic glass and/or expandable clays is complex. The behavior of these rocks appears to be completely dominated by dehydration of hydrous phases and, hence, should be critically dependent on fluid pressure. Valid extrapolation of the ambient-pressure results presented here to depths of interest for construction of a nuclear-waste repository will depend on a good understanding of the interaction of dehydration rates and fluid pressures, and of the effects of both micro- and macrofractures on the response of tuff masss

  18. A natural analogue for high-level waste in tuff: Chemical analysis and modeling of the Valles site

    International Nuclear Information System (INIS)

    Stockman, H.W.; Krumhansl, J.L.; Ho, C.K.; Kovach, L.; McConnell, V.S.

    1995-01-01

    The contact between an obsidian flow and a steep-walled tuff canyon was examined as an analogue for a high-level waste repository. The analogue site is located in the Valles Caldera in New Mexico, where a massive obsidian flow filled a paleocanyon in the Battleship Rock Tuff. The obsidian flow provided a heat source, analogous to waste panels or an igneous intrusion in a repository, and caused evaporation and migration of water. The tuff and obsidian samples were analyzed for major and trace elements and mineralogy by INAA, XRF, x-ray diffraction, and scanning electron microscopy and electron microprobe. Samples were also analyzed for D/H and 39 Ar/ 40 Ar isotopic composition. Overall, the effects of the heating event seem to have been slight and limited to the tuff nearest the contact. There is some evidence of devitrification and migration of volatiles in the tuff within 10 m of the contact, but variations in major and trace element chemistry are small and difficult to distinguish from the natural (pre-heating) variability of the rocks

  19. Laboratory studies of radionuclide migration in tuff

    International Nuclear Information System (INIS)

    Rundberg, R.S.; Mitchell, A.J.; Ott, M.A.; Thompson, J.L.; Triay, I.R.

    1989-01-01

    The movement of selected radionuclides has been observed in crushed tuff, intact tuff, and fractured tuff columns. Retardation factors and dispersivities were determined from the elution profiles. Retardation factors have been compared with those predicted on the basis of batch sorption studies. This comparison forms a basis for either validating distribution coefficients or providing evidence of speciation, including colloid formation. Dispersivities measured as a function of velocity provide a means of determining the effect of sorption kinetics or mass transfer on radionuclide migration. Dispersion is also being studied in the context of scaling symmetry to develop a basis for extrapolating from the laboratory scale to the field. 21 refs., 6 figs., 2 tabs

  20. Mechanical excavator performance in Yucca Mountain tuffs

    International Nuclear Information System (INIS)

    Ozdemir, L.; Hansen, F.D.

    1991-01-01

    A research effort of four phases is in progress at the Colorado School of Mines. The overall program will evaluate the cutability of welded tuff and other lithologies likely to be excavated at Yucca Mountain in the site characterization process. Several mechanical systems are considered with emphasis given to the tunnel boring machine. The research comprises laboratory testing, linear drag bit and disc cutter tests and potentially large-scale laboratory demonstrations to support potential use of a tunnel boring machine in welded tuff. Preliminary estimates of mechanical excavator performance in Yucca Mountain tuff are presented here. As phases of the research project are completed, well quantified estimates will be made of performance of mechanical excavators in the Yucca Mountain tuffs. 3 refs., 2 tabs

  1. Mechanical excavator performance in Yucca Mountain tuffs

    International Nuclear Information System (INIS)

    Ozdemir, L.; Hansen, F.D.

    1991-01-01

    A research effort of four phases is in progress at the Colorado School of Mines. The overall program will evaluate the cutability of welded tuff and other lithologies likely to be excavated at Yucca Mountain in the site characterization process. Several mechanical systems are considered with emphasis given to the tunnel boring machine. The research comprises laboratory testing, linear drag bit and disc cutter tests, and potentially large-scale lab. demonstrations to support potential use of a tunnel boring machine in welded tuff. Preliminary estimates of mechanical excavator performance in Yucca Mountain tuff are presented here. As phases of the research project are completed, well-quantified estimates will be made of performance of mechanical excavators in the Yucca Mountain tuffs

  2. Development of waste packages for tuff

    International Nuclear Information System (INIS)

    Rothman, A.J.

    1982-01-01

    The objective of this program is to develop nuclear waste packages that meet the Nuclear Regulatory Commission's requirements for a licensed repository in tuff at the Nevada Test Site. Selected accomplishments for FY82 are: (1) Selection, collection of rock, and characterization of suitable outcrops (for lab experiments); (2) Rock-water interactions (Bullfrog Tuff); (3) Corrosion tests of ferrous metals; (4) Thermal modeling of waste package in host rock; (5) Preliminary fabrication tests of alternate backfills (crushed tuff); (6) Reviewed Westinghouse conceptual waste package designs for tuff and began modification for unsaturated zone; and (7) Waste Package Codes (BARIER and WAPPA) now running on our computer. Brief discussions are presented for rock-water interactions, corrosion tests of ferrous metals, and thermal and radionuclide migration modelling

  3. Natural language solution to a Tuff problem

    International Nuclear Information System (INIS)

    Langkopf, B.S.; Mallory, L.H.

    1984-01-01

    A scientific data base, the Tuff Data Base, is being created at Sandia National Laboratories on the Cyber 170/855, using System 2000. It is being developed for use by scientists and engineers investigating the feasibility of locating a high-level radioactive waste repository in tuff (a type of volcanic rock) at Yucca Mountain on and adjacent to the Nevada Test Site. This project, the Nevada Nuclear Waste Storage Investigations (NNWSI) Project, is managed by the Nevada Operations Office of the US Department of Energy. A user-friendly interface, PRIMER, was developed that uses the Self-Contained Facility (SCF) command SUBMIT and System 2000 Natural Language functions and parametric strings that are schema resident. The interface was designed to: (1) allow users, with or without computer experience or keyboard skill, to sporadically access data in the Tuff Data Base; (2) produce retrieval capabilities for the user quickly; and (3) acquaint the users with the data in the Tuff Data Base. This paper gives a brief description of the Tuff Data Base Schema and the interface, PRIMER, which is written in Fortran V. 3 figures

  4. Flow in bedrock canyons.

    Science.gov (United States)

    Venditti, Jeremy G; Rennie, Colin D; Bomhof, James; Bradley, Ryan W; Little, Malcolm; Church, Michael

    2014-09-25

    Bedrock erosion in rivers sets the pace of landscape evolution, influences the evolution of orogens and determines the size, shape and relief of mountains. A variety of models link fluid flow and sediment transport processes to bedrock incision in canyons. The model components that represent sediment transport processes are increasingly well developed. In contrast, the model components being used to represent fluid flow are largely untested because there are no observations of the flow structure in bedrock canyons. Here we present a 524-kilometre, continuous centreline, acoustic Doppler current profiler survey of the Fraser Canyon in western Canada, which includes 42 individual bedrock canyons. Our observations of three-dimensional flow structure reveal that, as water enters the canyons, a high-velocity core follows the bed surface, causing a velocity inversion (high velocities near the bed and low velocities at the surface). The plunging water then upwells along the canyon walls, resulting in counter-rotating, along-stream coherent flow structures that diverge near the bed. The resulting flow structure promotes deep scour in the bedrock channel floor and undercutting of the canyon walls. This provides a mechanism for channel widening and ensures that the base of the walls is swept clear of the debris that is often deposited there, keeping the walls nearly vertical. These observations reveal that the flow structure in bedrock canyons is more complex than assumed in the models presently used. Fluid flow models that capture the essence of the three-dimensional flow field, using simple phenomenological rules that are computationally tractable, are required to capture the dynamic coupling between flow, bedrock erosion and solid-Earth dynamics.

  5. Mechanical tunnel excavation in welded tuff

    International Nuclear Information System (INIS)

    Sperry, P.E.

    1991-01-01

    The Technical Review Board for the US high-level radioactive waste facility at Yucca Mountain has recommended maximum use of open-quotes the most modern mechanical excavation techniques...in order to reduce disturbance to the rock walls and to achieve greater economy of time and cost.close quotes Tunnels for the waste repository at Yucca Mountain can be economically constructed with mechanical excavation equipment. This paper presents the results of mechanical excavation of a tunnel in welded tuff, similar to the tuffs of Yucca Mountain. These results are projected to excavation of emplacement drifts in Yucca Mountain using a current state-of-the-art tunnel boring machine (TBM)

  6. Issues related to field testing in tuff

    International Nuclear Information System (INIS)

    Zimmerman, R.M.

    1982-01-01

    This paper has brought out the unique properties of tuffs and related them to needs associated with their use as a host rock for a high level nuclear waste repository. Major issues of temperature, pore water, joints, and depositional patterns have been identified and related responses and impacts outlined in Table 1. Planned experiments have been outlined and their relationships to the rock mechanics issues summarized in Table 2. The conclusions from this paper are: (1) tuff is a complex rock and basic phenomenological understanding is incomplete; and (2) available field test facilities will be used for a series of experiments designed to improve phenomenological understanding and support repository design efforts

  7. Anisotropy of the Topopah Spring Member Tuff

    International Nuclear Information System (INIS)

    Martin, R.J. III; Boyd, P.J.; Haupt, R.W.; Price, R.H.

    1992-07-01

    Mechanical properties of the tuffaceous rocks within Yucca Mountain are needed for near and far-field modeling of the potential nuclear waste repository. If the mechanical properties are significantly anisotropic (i.e., direction-dependent), a more complex model is required. Relevant data from tuffs tested in earlier studies indicate that elastic and strength properties are anisotropic. This scoping study confirms the elastic anisotropy and concludes some tuffs are transversely isotropic. An approach for sampling and testing the rock to determine the magnitude of the anisotropy is proposed

  8. Transport of neptunium through Yucca Mountain tuffs

    International Nuclear Information System (INIS)

    Triay, I.R.; Robinson, B.A.; Mitchell, A.J.; Overly, C.M.; Lopez, R.M.

    1993-01-01

    Neptunium has a high solubility in groundwaters from Yucca Mountain [1]. Uranium in nuclear reactors produces 237 Np which has a half-life of 2.1 4 x 10 6 years. Consequently, the transport of 237 Np through tuffs is of major importance in assessing the performance of a high-level nuclear waste repository at Yucca Mountain. The objective of this work is to determine the amount of Np retardation that is provided by the minerals in Yucca Mountain tuffs as a function of groundwater chemistry

  9. Geologic map of the Paintbrush Canyon Area, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Dickerson, R.P.; Drake, R.M. II

    1998-01-01

    This geologic map is produced to support site characterization studies of Yucca Mountain, Nevada, site of a potential nuclear waste storage facility. The area encompassed by this map lies between Yucca Wash and Fortymile Canyon, northeast of Yucca Mountain. It is on the southern flank of the Timber Mountain caldera complex within the southwest Nevada volcanic field. Miocene tuffs and lavas of the Calico Hills Formation, the Paintbrush Group, and the Timber Mountain Group crop out in the area of this map. The source vents of the tuff cones and lava domes commonly are located beneath the thickest deposits of pyroclastic ejecta and lava flows. The rocks within the mapped area have been deformed by north- and northwest-striking, dominantly west-dipping normal faults and a few east-dipping normal faults. Faults commonly are characterized by well developed fault scarps, thick breccia zones, and hanging-wall grabens. Latest movement as preserved by slickensides on west-dipping fault scarps is oblique down towards the southwest. Two of these faults, the Paintbrush Canyon fault and the Bow Ridge fault, are major block-bounding faults here and to the south at Yucca Mountain. Offset of stratigraphic units across faults indicates that faulting occurred throughout the time these volcanic units were deposited

  10. Geologic map of the Paintbrush Canyon Area, Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Dickerson, R.P. [Geological Survey, Denver, CO (United States); Drake, R.M. II [Pacific Western Technologies, Ltd., Lakewood, CO (United States)

    1998-11-01

    This geologic map is produced to support site characterization studies of Yucca Mountain, Nevada, site of a potential nuclear waste storage facility. The area encompassed by this map lies between Yucca Wash and Fortymile Canyon, northeast of Yucca Mountain. It is on the southern flank of the Timber Mountain caldera complex within the southwest Nevada volcanic field. Miocene tuffs and lavas of the Calico Hills Formation, the Paintbrush Group, and the Timber Mountain Group crop out in the area of this map. The source vents of the tuff cones and lava domes commonly are located beneath the thickest deposits of pyroclastic ejecta and lava flows. The rocks within the mapped area have been deformed by north- and northwest-striking, dominantly west-dipping normal faults and a few east-dipping normal faults. Faults commonly are characterized by well developed fault scarps, thick breccia zones, and hanging-wall grabens. Latest movement as preserved by slickensides on west-dipping fault scarps is oblique down towards the southwest. Two of these faults, the Paintbrush Canyon fault and the Bow Ridge fault, are major block-bounding faults here and to the south at Yucca Mountain. Offset of stratigraphic units across faults indicates that faulting occurred throughout the time these volcanic units were deposited.

  11. Measuring and modeling water imbibition into tuff

    International Nuclear Information System (INIS)

    Peters, R.R.; Klavetter, E.A.; George, J.T.; Gauthier, J.H.

    1986-01-01

    Yucca Mountain (Nevada) is being investigated as a potential site for a high-level-radioactive-waste repository. The site combines a partially saturated hydrologic system and a stratigraphy of fractured, welded and nonwelded tuffs. The long time scale for site hydrologic phenomena makes their direct measurement prohibitive. Also, modeling is difficult because the tuffs exhibit widely varying, and often highly nonlinear hydrologic properties. To increase a basic understanding of both the hydrologic properties of tuffs and the modeling of flow in partially saturated regimes, the following tasks were performed, and the results are reported: (1) Laboratory Experiment: Water imbibition into a cylinder of tuff (taken from Yucca Mountain drill core) was measured by immersing one end of a dry sample in water and noting its weight at various times. The flow of water was approximately one-dimensional, filling the sample from bottom to top. (2) Computer Simulation: The experiment was modeled using TOSPAC (a one-dimensional, finite-difference computer program for simulating water flow in partially saturated, fractured, layered media) with data currently considered for use in site-scale modeling of a repository in Yucca Mountain. The measurements and the results of the modeling are compared. Conclusions are drawn with respect to the accuracy of modeling transient flow in a partially saturated, porous medium using a one-dimensional model and currently available hydrologic-property data

  12. Separations canyon decontamination facilities

    International Nuclear Information System (INIS)

    Hershey, J.H.

    1975-01-01

    Highly radioactive process equipment is decontaminated at the Savannah River Plant in specially equipped areas of the separations canyon building so that direct mechanical repairs or alterations can be made. Using these facilities it is possible to decontaminate and repair equipment such as 10- x 11-ft storage tanks, 8- x 8-ft batch evaporator pots and columns, 40-in. Bird centrifuges, canyon pumps and agitators, and various canyon piping systems or ''jumpers.'' For example, centrifuge or evaporator pots can be decontaminated and rebuilt for about 60 percent of the 1974 replacement cost. The combined facilities can decontaminate and repair 6 to 10 pieces of major equipment per year. Decontamination time varies with type of equipment and radioactivity levels encountered

  13. Separations canyon decontamination facilities

    International Nuclear Information System (INIS)

    Hershey, J.H.

    1975-05-01

    Highly radioactive process equipment is decontaminated at the Savannah River Plant in specially equipped areas of the separations canyon buildings so that direct mechanical repairs or alterations can be made. Using these facilities it is possible to decontaminate and repair equipment such as 10- x 11-ft storage tanks, 8- x 8-ft batch evaporator pots and columns, 40-in. Bird centrifuges, canyon pumps and agitators, and various canyon piping systems or ''jumpers.'' For example, centrifuge or evaporator pots can be decontaminated and rebuilt for about 60 percent of the 1974 replacement cost. The combined facilities can decontaminate and repair 6 to 10 pieces of major equipment per year. Decontamination time varies with type of equipment and radioactivity levels encountered. (U.S.)

  14. Fourmile Canyon Fire Findings

    Science.gov (United States)

    Russell Graham; Mark Finney; Chuck McHugh; Jack Cohen; Dave Calkin; Rick Stratton; Larry Bradshaw; Ned Nikolov

    2012-01-01

    The Fourmile Canyon Fire burned in the fall of 2010 in the Rocky Mountain Front Range adjacent to Boulder, Colorado. The fire occurred in steep, rugged terrain, primarily on privately owned mixed ponderosa pine and Douglas-fir forests. The fire started on September 6 when the humidity of the air was very dry (¡Ö

  15. Infiltration and Seepage Through Fractured Welded Tuff

    International Nuclear Information System (INIS)

    T.A. Ghezzehei; P.F. Dobson; J.A. Rodriguez; P.J. Cook

    2006-01-01

    The Nopal I mine in Pena Blanca, Chihuahua, Mexico, contains a uranium ore deposit within fractured tuff. Previous mining activities exposed a level ground surface 8 m above an excavated mining adit. In this paper, we report results of ongoing research to understand and model percolation through the fractured tuff and seepage into a mined adit both of which are important processes for the performance of the proposed nuclear waste repository at Yucca Mountain. Travel of water plumes was modeled using one-dimensional numerical and analytical approaches. Most of the hydrologic properly estimates were calculated from mean fracture apertures and fracture density. Based on the modeling results, we presented constraints for the arrival time and temporal pattern of seepage at the adit

  16. Infiltration and Seepage Through Fractured Welded Tuff

    Energy Technology Data Exchange (ETDEWEB)

    T.A. Ghezzehei; P.F. Dobson; J.A. Rodriguez; P.J. Cook

    2006-06-20

    The Nopal I mine in Pena Blanca, Chihuahua, Mexico, contains a uranium ore deposit within fractured tuff. Previous mining activities exposed a level ground surface 8 m above an excavated mining adit. In this paper, we report results of ongoing research to understand and model percolation through the fractured tuff and seepage into a mined adit both of which are important processes for the performance of the proposed nuclear waste repository at Yucca Mountain. Travel of water plumes was modeled using one-dimensional numerical and analytical approaches. Most of the hydrologic properly estimates were calculated from mean fracture apertures and fracture density. Based on the modeling results, we presented constraints for the arrival time and temporal pattern of seepage at the adit.

  17. Hydraulic characterization of hydrothermally altered Nopal tuff

    Energy Technology Data Exchange (ETDEWEB)

    Green, R.T.; Meyer-James, K.A. [Southwest Research Institute, San Antonio, TX (United States); Rice, G. [George Rice and Associates, San Antonio, TX (United States)

    1995-07-01

    Understanding the mechanics of variably saturated flow in fractured-porous media is of fundamental importance to evaluating the isolation performance of the proposed high-level radioactive waste repository for the Yucca Mountain site. Developing that understanding must be founded on the analysis and interpretation of laboratory and field data. This report presents an analysis of the unsaturated hydraulic properties of tuff cores from the Pena Blanca natural analog site in Mexico. The basic intent of the analysis was to examine possible trends and relationships between the hydraulic properties and the degree of hydrothermal alteration exhibited by the tuff samples. These data were used in flow simulations to evaluate the significance of a particular conceptual (composite) model and of distinct hydraulic properties on the rate and nature of water flow.

  18. Hydraulic characterization of hydrothermally altered Nopal tuff

    International Nuclear Information System (INIS)

    Green, R.T.; Meyer-James, K.A.; Rice, G.

    1995-07-01

    Understanding the mechanics of variably saturated flow in fractured-porous media is of fundamental importance to evaluating the isolation performance of the proposed high-level radioactive waste repository for the Yucca Mountain site. Developing that understanding must be founded on the analysis and interpretation of laboratory and field data. This report presents an analysis of the unsaturated hydraulic properties of tuff cores from the Pena Blanca natural analog site in Mexico. The basic intent of the analysis was to examine possible trends and relationships between the hydraulic properties and the degree of hydrothermal alteration exhibited by the tuff samples. These data were used in flow simulations to evaluate the significance of a particular conceptual (composite) model and of distinct hydraulic properties on the rate and nature of water flow

  19. Geologic map and upper Paleozoic stratigraphy of the Marble Canyon area, Cottonwood Canyon quadrangle, Death Valley National Park, Inyo County, California

    Science.gov (United States)

    Stone, Paul; Stevens, Calvin H.; Belasky, Paul; Montañez, Isabel P.; Martin, Lauren G.; Wardlaw, Bruce R.; Sandberg, Charles A.; Wan, Elmira; Olson, Holly A.; Priest, Susan S.

    2014-01-01

    This geologic map and pamphlet focus on the stratigraphy, depositional history, and paleogeographic significance of upper Paleozoic rocks exposed in the Marble Canyon area in Death Valley National Park, California. Bedrock exposed in this area is composed of Mississippian to lower Permian (Cisuralian) marine sedimentary rocks and the Jurassic Hunter Mountain Quartz Monzonite. These units are overlain by Tertiary and Quaternary nonmarine sedimentary deposits that include a previously unrecognized tuff to which we tentatively assign an age of late middle Miocene (~12 Ma) based on tephrochronologic analysis, in addition to the previously recognized Pliocene tuff of Mesquite Spring. Mississippian and Pennsylvanian rocks in the Marble Canyon area represent deposition on the western continental shelf of North America. Mississippian limestone units in the area (Tin Mountain, Stone Canyon, and Santa Rosa Hills Limestones) accumulated on the outer part of a broad carbonate platform that extended southwest across Nevada into east-central California. Carbonate sedimentation was interrupted by a major eustatic sea-level fall that has been interpreted to record the onset of late Paleozoic glaciation in southern Gondwana. Following a brief period of Late Mississippian clastic sedimentation (Indian Springs Formation), a rise in eustatic sea level led to establishment of a new carbonate platform that covered most of the area previously occupied by the Mississippian platform. The Pennsylvanian Bird Spring Formation at Marble Canyon makes up the outer platform component of ten third-order (1 to 5 m.y. duration) stratigraphic sequences recently defined for the regional platform succession. The regional paleogeography was fundamentally changed by major tectonic activity along the continental margin beginning in middle early Permian time. As a result, the Pennsylvanian carbonate shelf at Marble Canyon subsided and was disconformably overlain by lower Permian units (Osborne Canyon and

  20. Borehole stability in densely welded tuffs

    International Nuclear Information System (INIS)

    Fuenkajorn, K.; Daemen, J.J.K.

    1992-07-01

    The stability of boreholes, or more generally of underground openings (i.e. including shafts, ramps, drifts, tunnels, etc.) at locations where seals or plugs are to be placed is an important consideration in seal design for a repository (Juhlin and Sandstedt, 1989). Borehole instability or borehole breakouts induced by stress redistribution could negate the effectiveness of seals or plugs. Breakout fractures along the wall of repository excavations or exploratory holes could provide a preferential flowpath for groundwater or gaseous radionuclides to bypass the plugs. After plug installation, swelling pressures exerted by a plug could induce radial cracks or could open or widen preexisting cracks in the rock at the bottom of the breakouts where the tangential compressive stresses have been released by the breakout process. The purpose of the work reported here is to determine experimentally the stability of a circular hole in a welded tuff sample subjected to various external boundary loads. Triaxial and biaxial borehole stability tests have been performed on densely welded Apache Leap tuff samples and Topopah Spring tuff samples. The nominal diameter of the test hole is 13.3 or 14.4 mm for triaxial testing, and 25.4 mm for biaxial testing. The borehole axis is parallel to one of the principal stress axes. The boreholes are drilled through the samples prior to applying external boundary loads. The boundary loads are progressively increased until breakouts occur or until the maximum load capacity of the loading system has been reached. 74 refs

  1. Canyons off northwest Puerto Rico

    International Nuclear Information System (INIS)

    Gardner, W.D.; Glover, L.K.; Hollister, C.D.

    1980-01-01

    The Nuclear-Research Submarine NR-1 was used to study morphoplogy, sediment, and sediment-water interactions off the northwest coast of Puerto Rico. New detailed bathymetry from the surface-support ship, USS Portland, shows several submarine canyons in the area, some of them unreported previously. The north coast canyons, Arecibo, Tiberones and Quebradillas, are primarily erosional features although no recent turbidity-current evidence is seen. The canyons are presently filling with river-transported sediments. (orig./ME)

  2. Evaporative water loss from welded tuff

    International Nuclear Information System (INIS)

    Hadley, G.R.; Turner, J.R. Jr.

    1980-04-01

    Welded tuff is one of the many candidate rocks presently being considered as a host medium for the disposal of radioactive waste. In the case where the disposal site lies above the water table, the host rock will in general be only partially saturated. This condition leads to a number of mass transfer processes of interest, including evaporative drying, two-phase water flow due to pressure gradients, capillary movement, plus others. Although these processes have all been known about for decades, it is not clear at this time what the relative importance of each is with regard to geologic media in a waste disposal environment. In particular, there seems to be no data available for tuff that would allow an investigator to sort out mechanisms. This work is intended to be a start in that direction. This paper reports the measurement of water loss rate for welded tuff at various temperatures due to the action of evaporative drying. The initial saturation was unknown, but the average initial water content was found to be 7% by weight. The resulting data show that the water loss rate declines monotonically with time at a given temperature and increases with increasing temperature as expected. Somewhat surprising, however, is the fact that over 90% of the water from a sample was lost by evaporation at room temperature within 72 hours. All the water loss data, including that taken at temperatures as high as 150 0 C, are explained to within a factor of two by a simple evaporation front model. The latter assumes the water is lost by the molecular diffusion of water vapor from a receding evaporation front. The motion of the evaporation front seems to depend on mass balance rather than energy balance. Capillary forces and the resulting liquid diffusion are evidently not strong enough to wash out the evaporation front, since the front model seems to fit the data well

  3. Uniaxial compression test series on Bullfrog Tuff

    International Nuclear Information System (INIS)

    Price, R.H.; Jones, A.K.; Nimick, K.G.

    1982-04-01

    Nineteen uniaxial compressive experiments were performed on samples of the Bullfrog Member of the Crater Flat Tuff, obtained from drillhole USW-G1 at Yucca Mountain on the Nevada Test Site. The water saturated samples were deformed at a nominal strain rate of 10 -5 sec -1 , atmospheric pressure and room temperature. Resultant unconfined compressive strengths, axial strains to failure, Young's moduli and Poisson's ratios ranged from 4.63 to 153. MPa, .0028 to .0058, 2.03 to 28.9 GPa and .08 to .16, respectively

  4. High-temperature, large-volume, lavalike ash-flow tuffs without calderas in southwestern Idaho

    Science.gov (United States)

    Ekren, E.B.; McIntyre, David H.; Bennett, Earl H.

    1984-01-01

    that were traced over areas having diameters of about 100 km. These two sheets are the herein-named Swisher Mountain Tuff, which is about 13.8 m.y. old, and the Little Jacks Tuff, which is about 10 m.y. old. The Swisher Mountain Tuff was erupted from the Juniper Mountain volcanic center, a gentle dome that is not bounded by arcuate faults indicative of cauldron subsidence. The tuff is 200 m thick over a considerable area in and adjacent to its source. It apparently thins gradually toward its distal edges, and it is inferred to be uniformly distributed around its source at Juniper Mountain. The unit contains vitrophyres at various intervals from base to top, and, although the vitrophyres are, in general, flow layered and commonly flow brecciated, they occasionally contain well-defined pumice clasts. The vitrophyres indicate compound cooling, and, near the distal edges of the sheet, some of them probably represent complete cooling breaks. The Little Jacks Tuff onlaps the Swisher Mountain Tuff in expo sures east of Juniper Mountain, and it is inferred to have been erupted from a source on the part of the Owyhee Plateau that lies just east of the area studied. This inferred source area, like that at Juniper Mountain, is also expressed today as a gentle dome without structural features indicative of cauldron subsidence. The Little Jacks Tuff, in most exposures in the deep canyons of the Plateau, consists of at least four cooling units, and, in places in the eastern part of the studied area near the source area, it possibly comprises as many as six. Although there is no obvious evidence of erosion between the various cooling units, magnetic polarity measurements indicate that there were at least two magnetic reversals during the eruption interval of the Little Jacks Tuff. Like the Swisher Mountain Tuff, the Little Jacks has flattened pumice clasts in a few outcrops-principally at the bases of the various cooling units. The two tuff sequences are calc-a

  5. Is there excess argon in the Fish Canyon magmatic system?

    Science.gov (United States)

    Wilkinson, C. M.; Sherlock, S.; Kelley, S. P.; Charlier, B. L.

    2010-12-01

    Some phenocrysts from the Fish Canyon Tuff (San Juan volcanic field, south-western Colorado, USA) have yielded anomalously old 40Ar/39Ar apparent ages and yet the sanidine ages are sufficiently reproducible to allow its use as an international standard. The eruption age of the Fish Canyon tuff has recently been determined by high precision analysis and recalibration of the decay constants based on the sanidine standard at 28.305 ± 0.036 Ma [1], slightly younger than the generally accepted U-Pb age. Previously, minerals from the tuff have been used in various geochronological studies e.g., fission-track; U-Pb; Rb-Sr; K-Ar and 40Ar/39Ar, but U-Pb zircon ages which range 28.37 - 28.61 Ma appear to be older than the sanidine and other minerals, including biotite, yield older ages (27.41 - 28.25 Ma for biotite) [2]. In the Fish Canyon volcanic system, the erupted products are thought to exist in the magma chamber for significant periods prior to eruption [3] and then pass rapidly from a high temperature magmatic environment (where Ar is free to re-equilibrate among the minerals), to effectively being quenched upon eruption (where Ar becomes immobile). Artificially elevated ages, older than eruption age, have been identified in some 40Ar/39Ar geochronological studies (e.g. [4]). These older ages may either reflect; 1) argon accumulation in pheno- or xenocrysts (by radioactive decay of parent 40K), 2) excess argon (40ArE) incorporated into a mineral during crystallisation (via diffusion into the mineral lattice or hosted within fluid or melt inclusions) or 3) inherited radiogenic argon (the dated material contains a component older than the age of eruption) [5]. To better understand the effects of 40ArE on 40Ar/39Ar apparent ages we have conducted a detailed study of intra-grain grain age variations by UV-LAMP Ar-analysis. Analysis of polished thick sections has been performed in-situ using a 213nm laser and Nu Instruments Noblesse which is able to discriminate against

  6. The Whittard Canyon - A case study of submarine canyon processes

    Science.gov (United States)

    Amaro, T.; Huvenne, V. A. I.; Allcock, A. L.; Aslam, T.; Davies, J. S.; Danovaro, R.; De Stigter, H. C.; Duineveld, G. C. A.; Gambi, C.; Gooday, A. J.; Gunton, L. M.; Hall, R.; Howell, K. L.; Ingels, J.; Kiriakoulakis, K.; Kershaw, C. E.; Lavaleye, M. S. S.; Robert, K.; Stewart, H.; Van Rooij, D.; White, M.; Wilson, A. M.

    2016-08-01

    Submarine canyons are large geomorphological features that incise continental shelves and slopes around the world. They are often suggested to be biodiversity and biomass hotspots, although there is no consensus about this in the literature. Nevertheless, many canyons do host diverse faunal communities but owing to our lack of understanding of the processes shaping and driving this diversity, appropriate management strategies have yet to be developed. Here, we integrate all the current knowledge of one single system, the Whittard Canyon (Celtic Margin, NE Atlantic), including the latest research on its geology, sedimentology, geomorphology, oceanography, ecology, and biodiversity in order to address this issue. The Whittard Canyon is an active system in terms of sediment transport. The net suspended sediment transport is mainly up-canyon causing sedimentary overflow in some upper canyon areas. Occasionally sediment gravity flow events do occur, some possibly the result of anthropogenic activity. However, the role of these intermittent gravity flows in transferring labile organic matter to the deeper regions of the canyon appears to be limited. More likely, any labile organic matter flushed downslope in this way becomes strongly diluted with bulk material and is therefore of little food value for benthic fauna. Instead, the fresh organic matter found in the Whittard Channel mainly arrives through vertical deposition and lateral transport of phytoplankton blooms that occur in the area during spring and summer. The response of the Whittard Canyon fauna to these processes is different in different groups. Foraminiferal abundances are higher in the upper parts of the canyon and on the slope than in the lower canyon. Meiofaunal abundances in the upper and middle part of the canyon are higher than on adjacent slopes, but lower in the deepest part. Mega- and macrofauna abundances are higher in the canyon compared with the adjacent slope and are higher in the eastern than

  7. In defense of Magnetite-Ilmenite Thermometry in the Bishop Tuff and its implication for gradients in silicic magma reservoirs

    Science.gov (United States)

    Evans, Bernard W; Hildreth, Edward; Bachmann, Olivier; Scaillet, Bruno

    2016-01-01

    Despite claims to the contrary, the compositions of magnetite and ilmenite in the Bishop Tuff correctly record the changing conditions of T and fO2 in the magma reservoir. In relatively reduced (∆NNO magmas (e.g., Bishop Tuff, Taupo units), Ti behaves compatibly (DTi ≈ 2-3.5), leading to a decrease in TiO2 activity in the melt with cooling and fractionation. In contrast, FeTi-oxides are poorer in TiO2 in more oxidized magmas (∆NNO > 1, e.g., Fish Canyon Tuff, Pinatubo), and the d(aTiO2)/dT slope can be negative. Biotite, FeTi-oxides, liquid, and possibly plagioclase largely maintained equilibrium in the Bishop Tuff magma (unlike the pyroxenes, and cores of quartz, sanidine, and zircon) prior ro and during a mixing event triggered by a deeper recharge, which, based on elemental diffusion profiles in minerals, took place at least several decades before eruption. Equilibrating phases and pumice compositions show evolving chemical variations that correlate well with mutually consistent temperatures based on the FeTi-oxides, sanidine-plagioclase, and ∆18O quartz-magnetite pairs. Early Bishop Tuff (EBT) temperatures are lower (700 to ~780‎°C) than temperatures (780 to >820°C) registered in Late Bishop Tuff (LBT), the latter defined here not strictly stratigraphically, but by the presence of orthopyroxene and reverse-zoned rims on quartz and sanidine. The claimed similarity in compositions, Zr-saturation temperatures and thermodynamically calculated temperatures (730-740°C) between EBT and less evolved LBT reflect the use of glass inclusions in quartz cores in LBT that were inherited from the low temperature rhyolitic part of the reservoir characteristic of the EBT. LBT temperatures as high as 820°C, the preservation of orthopyroxene, and the presence of reverse-zoned minerals (quartz, sanidine, zircons) are consistent with magma recharge at the base of the zoned reservoir, heating the cooler rhyolitic melt, partly remelting cumulate mush, and introducing

  8. New York Canyon Stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Raemy, Bernard

    2012-06-21

    The New York Canyon Stimulation Project was to demonstrate the commercial application of Enhanced Geothermal System techniques in Buena Vista Valley area of Pershing County, Nevada. From October 2009 to early 2012, TGP Development Company aggressively implemented Phase I of Pre-Stimulation and Site/Wellbore readiness. This included: geological studies; water studies and analyses and procurement of initial permits for drilling. Oversubscription of water rights and lack of water needed for implementation of EGS were identified and remained primary obstacles. Despite extended efforts to find alternative solutions, the water supply circumstances could not be overcome and led TGP to determine a "No Go" decision and initiate project termination in April 2012.

  9. Major-element geochemistry of the Silent Canyon--Black Mountain peralkaline volcanic centers, northwestern Nevada Test Site: applications to an assessment of renewed volcanism

    International Nuclear Information System (INIS)

    Crowe, B.M.; Sargent, K.A.

    1979-01-01

    The Silent Canyon and Black Mountain volcanic centers are located in the northern part of the Nevada Test Site. The Silent Canyon volcanic center is a buried cauldron complex of Miocene age (13 to 15 m.y.). Black Mountain volcanic center is an elliptical-shaped cauldron complex of late Miocene age. The lavas and tuffs of the two centers comprise a subalkaline-peralkaline association. Rock types range from quartz normative subalkaline trachyte and rhyolite to peralkaline commendite. The Gold Flat Member of the Thirsty Canyon Tuff (Black Mountain) is a pantellerite. The major-element geochemistry of the Black Mountain--Silent Canyon volcanic centers differ in the total range and distribution of SiO 2 , contents, the degree of peralkalinity (molecular Na 2 O + K 2 O > Al 2 O 3 ) and in the values of total iron and alumina through the range of rock types. These differences indicate that the suites were unrelated and evolved from differing magma bodies. The Black Mountain volcanic cycle represents a renewed phase of volcanism following cessation of the Timber Mountain--Silent Canyon volcanic cycles. Consequently, there is a small but numerically incalculable probability of recurrence of Black Mountain-type volcanism within the Nevada Test Site region. This represents a potential risk with respect to deep geologic storage of high-level radioactive waste at the Nevada Test Site

  10. Probing the volcanic-plutonic connection and the genesis of crystal-rich rhyolite in a deeply dissected supervolcano in the Nevada Great Basin: Source of the late Eocene Caetano Tuff

    Science.gov (United States)

    Watts, Kathryn E.; John, David A.; Colgan, Joseph P.; Henry, Christopher D.; Bindeman, Ilya N.; Schmitt, Axel K.

    2016-01-01

    Late Cenozoic faulting and large-magnitude extension in the Great Basin of the western USA has created locally deep windows into the upper crust, permitting direct study of volcanic and plutonic rocks within individual calderas. The Caetano caldera in north–central Nevada, formed during the mid-Tertiary ignimbrite flare-up, offers one of the best exposed and most complete records of caldera magmatism. Integrating whole-rock geochemistry, mineral chemistry, isotope geochemistry and geochronology with field studies and geologic mapping, we define the petrologic evolution of the magmatic system that sourced the >1100 km3Caetano Tuff. The intra-caldera Caetano Tuff is up to ∼5 km thick, composed of crystal-rich (30–45 vol. %), high-silica rhyolite, overlain by a smaller volume of comparably crystal-rich, low-silica rhyolite. It defies classification as either a monotonous intermediate or crystal-poor zoned rhyolite, as commonly ascribed to ignimbrite eruptions. Crystallization modeling based on the observed mineralogy and major and trace element geochemistry demonstrates that the compositional zonation can be explained by liquid–cumulate evolution in the Caetano Tuff magma chamber, with the more evolved lower Caetano Tuff consisting of extracted liquids that continued to crystallize and mix in the upper part of the chamber following segregation from a cumulate-rich, and more heterogeneous, source mush. The latter is represented in the caldera stratigraphy by the less evolved upper Caetano Tuff. Whole-rock major, trace and rare earth element geochemistry, modal mineralogy and mineral chemistry, O, Sr, Nd and Pb isotope geochemistry, sanidine Ar–Ar geochronology, and zircon U–Pb geochronology and trace element geochemistry provide robust evidence that the voluminous caldera intrusions (Carico Lake pluton and Redrock Canyon porphyry) are genetically equivalent to the least evolved Caetano Tuff and formed from magma that remained in the lower chamber after

  11. Probing the volcanic-plutonic connection and the genesis of crystal-rich rhyolite in a deeply dissected supervolcano in the Nevada Great Basin: Source of the late Eocene Caetano Tuff

    Science.gov (United States)

    Watts, Kathryn E.; John, David A.; Colgan, Joseph P.; Henry, Christopher D.; Bindeman, Ilya N.; Schmitt, Axel K.

    2016-01-01

    Late Cenozoic faulting and large-magnitude extension in the Great Basin of the western USA has created locally deep windows into the upper crust, permitting direct study of volcanic and plutonic rocks within individual calderas. The Caetano caldera in north–central Nevada, formed during the mid-Tertiary ignimbrite flare-up, offers one of the best exposed and most complete records of caldera magmatism. Integrating whole-rock geochemistry, mineral chemistry, isotope geochemistry and geochronology with field studies and geologic mapping, we define the petrologic evolution of the magmatic system that sourced the >1100 km3Caetano Tuff. The intra-caldera Caetano Tuff is up to ∼5 km thick, composed of crystal-rich (30–45 vol. %), high-silica rhyolite, overlain by a smaller volume of comparably crystal-rich, low-silica rhyolite. It defies classification as either a monotonous intermediate or crystal-poor zoned rhyolite, as commonly ascribed to ignimbrite eruptions. Crystallization modeling based on the observed mineralogy and major and trace element geochemistry demonstrates that the compositional zonation can be explained by liquid–cumulate evolution in the Caetano Tuff magma chamber, with the more evolved lower Caetano Tuff consisting of extracted liquids that continued to crystallize and mix in the upper part of the chamber following segregation from a cumulate-rich, and more heterogeneous, source mush. The latter is represented in the caldera stratigraphy by the less evolved upper Caetano Tuff. Whole-rock major, trace and rare earth element geochemistry, modal mineralogy and mineral chemistry, O, Sr, Nd and Pb isotope geochemistry, sanidine Ar–Ar geochronology, and zircon U–Pb geochronology and trace element geochemistry provide robust evidence that the voluminous caldera intrusions (Carico Lake pluton and Redrock Canyon porphyry) are genetically equivalent to the least evolved Caetano Tuff and formed from magma that remained in the lower chamber after

  12. PRELIMINARY PALEOMAGNETIC RESULTS FROM OUTFLOW EOCENE-OLIGOCENE ASH FLOW TUFFS FROM THE WESTERN MARGIN OF THE SAN LUIS BASIN: IMPLICATION FOR THE KINEMATIC EVOLUTION OF THE RIO GRANDE RIFT

    Science.gov (United States)

    Mason, S. N.; Geissman, J. W.; Sussman, A. J.

    2009-12-01

    In the Rio Grande rift (RGR), a late Cenozoic continental rift from central Colorado to southern New Mexico, hanging wall margins typically contain en echelon normal fault systems with intervening areas of typically complex structure, called relay zones. Relay zones transfer displacement through complex strain patterns and eventual linkage of faults and hold clues as to how fault zones initiate and grow. The western margin of the RGR at the latitude of the San Luis basin (SLB) exposes laterally continuous Eocene-Oligocene volcanic rocks, well-correlated by 40Ar/39Ar data, and well-preserved rift structures. Ash flow tuffs are usually excellent recorders of the instantaneous geomagnetic field and five ash flow tuffs (ca. 32.3 to 27.3 Ma; including the Saguache Creek, La Jara Canyon, Masonic Park, Fish Canyon, and Carpenter Ridge tuffs) have been sampled in spatial detail along west to east transects of the eastern San Juan volcanic field to the westernmost margin of the RGR at the SLB. Data obtained from our sampling approach will yield a comprehensive definition of relative vertical-axis rotations across the area and will be used to assess the timing of RGR fault linkages. Preliminary paleomagnetic data from the Masonic Park tuff (ca. 28.2 Ma) suggest up to ~17° clockwise rotation between sample locations on the Colorado Plateau and locations to the east, nearest the western margin of the RGR. Preliminary data from the Fish Canyon tuff (ca. 27.8 Ma) show a ~12° clockwise rotation. The relative clockwise vertical-axis rotation of sampling sites in both ash flow tuffs nearest the RGR margin suggests that relay zone development with attending vertical-axis rotation played an important role in the opening of the northern RGR. Our data set is not sufficiently robust at present to test the hypothesis that rotation was taking place concurrently with eruption of these large-volume ash flow tuffs in the early Oligocene, but it is a possibility and if so, the RGR at the

  13. 236-Z canyon utilization study

    International Nuclear Information System (INIS)

    Dixon, D.R.

    1977-01-01

    The 236-Z canyon contains equipment for repurification of plutonium and recovery of plutonium from scrap material. To meet production requirements of Fast Flux Test Facility/Clinch River Breeder Reactor oxide with the existing plant, several new pieces of equipment will be needed in the future. More storage space and a better accountability system are needed to support this increased production. The available canyon space needs to be utilized to its fullest in order to accommodate the new equipment. The purpose of this document is to identify the new pieces of equipment, show how they fit into the flowsheet, and locate them in the canyon

  14. 2010 Pacific Gas and Electric Diablo Canyon Power Plant (DCPP): Diablo Canyon, CA Central Coast

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Diablo Canyon Power Plant (DCPP) LiDAR and Imagery datasets are comprised of three separate LiDAR surveys: Diablo Canyon (2010), Diablo Canyon (2010), and San...

  15. Structural character of the northern segment of the Paintbrush Canyon fault, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Dickerson, R.P.; Spengler, R.W.

    1994-01-01

    Detailed mapping of exposed features along the northern part of the Paintbrush Canyon fault was initiated to aid in construction of the computer-assisted three-dimensional lithostratigraphic model of Yucca Mountain, to contribute to kinematic reconstruction of the tectonic history of the Paintbrush Canyon fault, and to assist in the interpretation of geophysical data from Midway Valley. Yucca Mountain is segmented into relatively intact blocks of east-dipping Miocene volcanic strata, bounded by north-striking, west-dipping high-angle normal faults. The Paintbrush Canyon fault, representing the easternmost block-bounding normal fault, separates Fran Ridge from Midway Valley and continues northward across Yucca Wash to at least the southern margin of the Timber Mountain Caldera complex. South of Yucca Wash, the Paintbrush Canyon Fault is largely concealed beneath thick Quaternary deposits. Bedrock exposures to the north reveal a complex fault, zone, displaying local north- and west-trending grabens, and rhombic pull-apart features. The fault scarp, discontinuously exposed along a mapped length of 8 km north of Yucca Wash, dips westward by 41 degrees to 74 degrees. Maximum vertical offset of the Rhyolite of Comb Peak along the fault measures about 210 m in Paintbrush Canyon and, on the basis of drill hole information, vertical offset of the Topopoah Spring Tuff is about 360 m near the northern part of Fran Ridge. Observed displacement along the fault in Paintbrush Canyon is down to the west with a component of left-lateral oblique slip. Unlike previously proposed tectonic models, strata adjacent to the fault dip to the east. Quaternary deposits do not appear displaced along the fault scarp north of Yucca Wash, but are displaced in trenches south of Yucca Wash

  16. First phase of small diameter heater experiments in tuff

    International Nuclear Information System (INIS)

    Zimmerman, R.M.

    1983-01-01

    As part of the Nevada Nuclear Waste Storage Investigations (NNWSI) project, we have undertaken small diameter heater experiments in the G-Tunnel Underground Facility on the Nevada Test Site (NTS). These experiments are to evaluate the thermal and hydrothermal behavior which might be encountered if heat producing nuclear waste were disposed of in welded and nonwelded tuffs. The two Phase I experiments discussed have focused on vertical borehole emplacements. In each experiment, temperatures were measured along the surface of the 10.2-cm-dia heater and the 12.7-cm-dia boreholes. For each experiment, measurements were compared with computer model representations. Maximum temperatures reached were: 196 0 C for the welded tuff after 21 days of operations at 800W and 173 0 C for the nonwelded tuff after 35 days of operations at 500W. Computed results indicate that the same heat transfer model (includes conduction and radiation only) can describe the behavior of both tuffs using empirical techniques to describe pore water vaporization. Hydrothermal measurements revealed heat-indiced water migration. Results indicated that small amounts of liquid water migrated into the welded tuff borehole early in the heating period. Once the rock-wall temperatures exceeded 94 0 C, in both tuffs, there was mass transport of water vapor as evidence indicated condensation cooler regions. Borehole pressures remained essentially ambient during the thermal periods

  17. Mineral resources of the Desolation Canyon, Turtle Canyon, and Floy Canyon Wilderness Study Areas, Carbon Emery, and Grand counties, Utah

    International Nuclear Information System (INIS)

    Cashion, W.B.; Kilburn, J.E.; Barton, H.N.; Kelley, K.D.; Kulik, D.M.; McDonnell, J.R.

    1990-09-01

    This paper reports on the Desolation Canyon, Turtle Canyon, and Floy Canyon Wilderness Study Areas which include 242,000 acres, 33,690 acres, and 23,140 acres. Coal deposits underlie all three study areas. Coal zones in the Blackhawk and Nelsen formations have identified bituminous coal resources of 22 million short tons in the Desolation Canyon Study Area, 6.3 million short tons in the Turtle Canyon Study Area, and 45 million short tons in the Floy Canyon Study Area. In-place inferred oil shale resources are estimated to contain 60 million barrels in the northern part of the Desolation Canyon area. Minor occurrences of uranium have been found in the southeastern part of the Desolation Canyon area and in the western part of the Floy Canyon area. Mineral resource potential for the study areas is estimated to be for coal, high for all areas, for oil and gas, high for the northern tract of the Desolation Canyon area and moderate for all other tracts, for bituminous sandstone, high for the northern part of the Desolation Canyon area, and low for all other tracts, for oil shale, low in all areas, for uranium, moderate for the Floy Canyon area and the southeastern part of the Desolation Canyon area and low for the remainder of the areas, for metals other than uranium, bentonite, zeolites, and geothermal energy, low in all areas, and for coal-bed methane unknown in all three areas

  18. Formative flow in bedrock canyons

    Science.gov (United States)

    Venditti, J. G.; Kwoll, E.; Rennie, C. D.; Church, M. A.

    2017-12-01

    In alluvial channels, it is widely accepted that river channel configuration is set by a formative flow that represents a balance between the magnitude and frequency of flood flows. The formative flow is often considered to be one that is just capable of filling a river channel to the top of its banks. Flows much above this formative flow are thought to cause substantial sediment transport and rearrange the channel morphology to accommodate the larger flow. This idea has recently been extended to semi-alluvial channels where it has been shown that even with bedrock exposed, the flows rarely exceed that required to entrain the local sediment cover. What constitutes a formative flow in a bedrock canyon is not clear. By definition, canyons have rock walls and are typically incised vertically, removing the possibility of the walls being overtopped, as can occur in an alluvial channel at high flows. Canyons are laterally constrained, have deep scour pools and often have width to maximum depth ratios approaching 1, an order of magnitude lower than alluvial channels. In many canyons, there are a sequence of irregularly spaced scour pools. The bed may have intermittent or seasonal sediment cover, but during flood flows the sediment bed is entrained leaving a bare bedrock channel. It has been suggested that canyons cut into weak, well-jointed rock may adjust their morphology to the threshold for block plucking because the rock bed is labile during exceptionally large magnitude flows. However, this hypothesis does not apply to canyons cut into massive crystalline rock where abrasion is the dominant erosion process. Here, we argue that bedrock canyon morphology is adjusted to a characteristic flow structure developed in bedrock canyons. We show that the deeply scoured canyon floor is adjusted to a velocity inversion that is present at low flows, but gets stronger at high flows. The effect is to increase boundary shear stresses along the scour pool that forms in constricted

  19. Photon Shielding Features of Quarry Tuff

    Directory of Open Access Journals (Sweden)

    Vega-Carrillo Hector Rene

    2017-01-01

    Full Text Available Cantera is a quarry tuff widely used in the building industry; in this work the shielding features of cantera were determined. The shielding characteristics were calculated using XCOM and MCNP5 codes for 0.03, 0.07, 0.1, 0.3, 0.662, 1, 2, and 3 MeV photons. With XCOM the mass interaction coefficients, and the total mass attenuation coefficients, were calculated. With the MCNP5 code a transmission experiment was modelled using a point-like source located 42 cm apart from a point-like detector. Between the source and the detector, cantera pieces with different thickness, ranging from 0 to 40 cm were included. The collided and uncollided photon fluence, the Kerma in air and the Ambient dose equivalent were estimated. With the uncollided fluence the linear attenuation coefficients were determined and compared with those calculated with XCOM. The linear attenuation coefficient for 0.662 MeV photons was compared with the coefficient measured with a NaI(Tl-based γ-ray spectrometer and a 137Cs source.

  20. Transport properties of Topopah Spring tuff

    International Nuclear Information System (INIS)

    Lin, W.; Daily, W.

    1984-10-01

    Electrical resistivity, ultrasonic P-waves velocity, and water permeability were measured simultaneously on both intact and fractured Topopah Spring tuff samples at a confining pressure of 5.0 MPa, pore pressures to 2.5 MPa, and temperatures to 140 0 C. The tested samples were subjected to three dehydration and rehydration cycles. The dehydrations were accomplished at a temperature of 140 0 C, and the rehydrations were accomplished at various combinations of temperature and pore pressures so that the wetting fluid was either liquid water, steam or both. The electrical resistivity measurements indicate that for the intact sample, the drying and resaturation took place fairly uniformly throughout the sample. On the other hand, for the fractured sample, the drying and resaturation was spatially quite nonuniform. When samples had been subjected to 5 MPa of confining pressure and 140 0 C for several weeks, a gradual monotonic drift in resistivity was measured (decreasing resistivity when dry; increasing resistivity when wet). This may be the result of either minerological changes or grain boundary movement. In any case, the phenomenon may have important consequences on long term repository performance, and should be studied further. The permeability of the intact sample was independent of temperature, dehydration and rehydration cycles, and time. The permeability of the fractured sample, initially dominated by the fracture, decreased by about one order of magnitude after each dehydration and rehydration cycle. 11 references, 12 figures, 3 tables

  1. Radionuclide transport and retardation in tuff

    International Nuclear Information System (INIS)

    Vine, E.N.; Bayhurst, B.P.; Daniels, W.R.; DeVilliers, S.J.; Erdal, B.R.; Lawrence, F.O.; Wolfsberg, K.

    1980-01-01

    Batch measurements provide an understanding of which experimental variables are important. For example, sorption ratios vary little with particle size (and surface area); however, groundwater composition and rock composition are quite important. A general correlation has been identified between mineralogy (major phases) and degree of sorption for strontium, cesium, and barium. Although these are approximate, a more detailed analysis may be possible as more samples are studied and the data base increased. Data from crushed tuff columns indicate that, except in simple cases where sorption coefficients are relatively low, and ion-exchange equilibria not only exist but are the dominant mechanism for removal of radioisotopes from solution, the simple relation between the sorption ratio R/sub d/ (or K/sub d/) and the relative velocity of radionuclides with respect to groundwater velocity may be insufficient to permit accurate modeling of the retardation of radionuclides. Additional work on whole core columns and larger blocks of intact material is required to better understand radionuclide sorption and transport through rock

  2. Magnetic properties in an ash flow tuff with continuous grain size variation: a natural reference for magnetic particle granulometry

    Science.gov (United States)

    Till, J.L.; Jackson, M.J.; Rosenbaum, J.G.; Solheid, P.

    2011-01-01

    The Tiva Canyon Tuff contains dispersed nanoscale Fe-Ti-oxide grains with a narrow magnetic grain size distribution, making it an ideal material in which to identify and study grain-size-sensitive magnetic behavior in rocks. A detailed magnetic characterization was performed on samples from the basal 5 m of the tuff. The magnetic materials in this basal section consist primarily of (low-impurity) magnetite in the form of elongated submicron grains exsolved from volcanic glass. Magnetic properties studied include bulk magnetic susceptibility, frequency-dependent and temperature-dependent magnetic susceptibility, anhysteretic remanence acquisition, and hysteresis properties. The combined data constitute a distinct magnetic signature at each stratigraphic level in the section corresponding to different grain size distributions. The inferred magnetic domain state changes progressively upward from superparamagnetic grains near the base to particles with pseudo-single-domain or metastable single-domain characteristics near the top of the sampled section. Direct observations of magnetic grain size confirm that distinct transitions in room temperature magnetic susceptibility and remanence probably denote the limits of stable single-domain behavior in the section. These results provide a unique example of grain-size-dependent magnetic properties in noninteracting particle assemblages over three decades of grain size, including close approximations of ideal Stoner-Wohlfarth assemblages, and may be considered a useful reference for future rock magnetic studies involving grain-size-sensitive properties.

  3. Diablo Canyon ECCS enhancements

    International Nuclear Information System (INIS)

    Lin, A.; Lee, T.P.; Walter, L.E.

    2004-01-01

    Diablo Canyon Power Plant (DCPP) operated by Pacific Gas and Electric Co. (PG and E) is a Westinghouse designed four loop plant. In recent years, several issues were identified regarding the compliance of the Emergency Core Cooling System (ECCS) surveillance tests to the ECCS analyses assumptions. These concerns are related mostly to the High Head Safety Injection (HHSI) and the Intermediate Head Safety Injection (IHSI) systems where the injection line throttle valves are adjusted during outage surveillance testing to ensure compliance with the Technical Specifications (TS). To resolve all of the identified issues PG and E performed an ECCS reanalysis and upgraded the ECCS surveillance test program and also had Westinghouse perform a containment reanalysis using their latest model. As a result of these plant specific enhancement efforts, DCPP widened the operating window for TS surveillance testing, lowered the ECCS pumps' acceptance performance curves, and re-gained Peak Clad Temperature (PCT) and containment peak pressure margins. These enhancements are generically applicable to other plants and are addressed in this paper. (author)

  4. Mechanical characterization of densely welded Apache Leap tuff

    International Nuclear Information System (INIS)

    Fuenkajorn, K.; Daemen, J.J.K.

    1991-06-01

    An empirical criterion is formulated to describe the compressive strength of the densely welded Apache Leap tuff. The criterion incorporates the effects of size, L/D ratio, loading rate and density variations. The criterion improves the correlation between the test results and the failure envelope. Uniaxial and triaxial compressive strengths, Brazilian tensile strength and elastic properties of the densely welded brown unit of the Apache Leap tuff have been determined using the ASTM standard test methods. All tuff samples are tested dry at room temperature (22 ± 2 degrees C), and have the core axis normal to the flow layers. The uniaxial compressive strength is 73.2 ± 16.5 MPa. The Brazilian tensile strength is 5.12 ± 1.2 MPa. The Young's modulus and Poisson's ratio are 22.6 ± 5.7 GPa and 0.20 ± 0.03. Smoothness and perpendicularity do not fully meet the ASTM requirements for all samples, due to the presence of voids and inclusions on the sample surfaces and the sample preparation methods. The investigations of loading rate, L/D radio and cyclic loading effects on the compressive strength and of the size effect on the tensile strength are not conclusive. The Coulomb strength criterion adequately represents the failure envelope of the tuff under confining pressures from 0 to 62 MPa. Cohesion and internal friction angle are 16 MPa and 43 degrees. The brown unit of the Apache Leap tuff is highly heterogeneous as suggested by large variations of the test results. The high intrinsic variability of the tuff is probably caused by the presence of flow layers and by nonuniform distributions of inclusions, voids and degree of welding. Similar variability of the properties has been found in publications on the Topopah Spring tuff at Yucca Mountain. 57 refs., 32 figs., 29 tabs

  5. Deepwater Canyons 2013: Pathways to the Abyss

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Leg I focused on biological objectives in Norfolk Canyon, with some sampling in Baltimore Canyon. Leg II focused on archaeological targets in and around the Norfolk...

  6. Dehydration and rehydration of a tuff vitrophyre

    International Nuclear Information System (INIS)

    Vaniman, D.; Bish, D., Chipera, S.

    1993-01-01

    The basal vitrophyre of the Topopah Spring Member of the Paintbrush Tuff at Yucca Mountain, Nevada, is a perlitic glass with 2.8 to 4.6% water. The dehydration of this vitrophyre was studied by thermogravimetric analysis (TGA) and by isothermal heating at 50 degrees, 100 degrees, 200 degrees, and 400 degrees C for 3.4 years followed by 1.1 years of rehydration at high controlled humidity (∼79% relative humidity). No crystallization of the glass was observed in long-term dehydration or rehydration; the only observed chemical alteration was loss of up to 60% of original fluorine. TGA studies show a characteristic two-stage dehydration of the vitrophyre, with two-thirds to three-fourths weight loss occurring most rapidly at temperatures ranging from 278 degrees to 346 degrees C in 10 degrees C/min heating experiments. The remaining water, about 1% in all of the vitrophyre samples studied regardless of total water content, is lost only on second-stage heating to temperatures above 650 degrees C. Long-term isothermal heating at ≤400 degrees C releases only the first-stage water. Loss of essentially all first-stage water occurred in less than 1 hour at 400 degrees C; proportionately lower losses were obtained at 200 degrees and 100 degrees C. Small (0.2%) water loss occurred in the 50 degrees C experiment. A time-temperature-dehydration diagram generated from the isothermal heating data shows a clustering of dehydration contours that are the equilibrium equivalent of the rapid first-stage water loss in dynamic TGA experiments. These dry-heating experiments provide an end-member characterization of glass transformations for comparison with water-saturated heating experiments in which glass alteration is prominent. 29 figs., 7 figs., 7 tabs

  7. Magnetism and magnetic mineralogy of ash flow tuffs from Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Schlinger, C.M.; Veblen, D.R.; Rosenbaum, J.G.

    1991-01-01

    The magnetic susceptibility χ and remanent magnetization of an ash flow sheet are profoundly influenced by cooling history after emplacement. Maxima and minima in χ measured along profiles at Yucca Mountain, Nevada, identify persistent magnetic marker horizons within vitric portions of the Tiva Canyon and underlying Topopah Spring Members of the Paintbrush Tuff. The observed stratigraphic changes in magnetic properties reflect variations in amounts and mineralogy of Fe-Ti oxide phenocrysts, and the presence, shape, size, and mineralogy of magnetic Fe-oxide microcrystals that precipitated at high temperature after emplacement of each sheet. The size variations of the precipitated Fe-oxides, which were established using transmission electron microscopy (TEM) and petrographic observation, are consistent both with variations in magnetic susceptibility measured at the outcrop and with variations in the intensity of remanent magnetization. Several interpretations of the shape anisotropy of the precipitated Fe-oxide are possible, including growth by a dislocation mechanism. Additionally, the observed elongation of precipitated microcrystals is consistent with theoretical predictions for growth in a uniaxial stress field. Susceptibility variations as established at the outcrop, as well as in the borehole, offer a potentially useful tool for stratigraphic correlation of ash flow sheets

  8. 78 FR 48670 - Boulder Canyon Project

    Science.gov (United States)

    2013-08-09

    ... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Canyon Project (BCP) electric service provided by the Western Area Power Administration (Western). The... INFORMATION: Hoover Dam, authorized by the Boulder Canyon Project Act (45 Stat. 1057, December 21, 1928), sits...

  9. 77 FR 48151 - Boulder Canyon Project

    Science.gov (United States)

    2012-08-13

    ... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Canyon Project (BCP) electric service provided by the Western Area Power Administration (Western). The... INFORMATION: Hoover Dam, authorized by the Boulder Canyon Project Act (45 Stat. 1057, December 21, 1928), sits...

  10. Pyritic ash-flow tuff, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Castor, S.B.; Tingley, J.V.; Bonham, H.F. Jr.

    1994-01-01

    The Yucca Mountain site is underlain by a 1,500-m-thick Miocene volcanic sequence that comprises part of the southwestern Nevada volcanic field. Rocks of this sequence, which consists mainly of ash-flow tuff sheets with minor flows and bedded tuff, host precious metal mineralization in several areas as near as 10 km from the site. In two such areas, the Bullfrog and Bare Mountain mining districts, production and reserves total over 60 t gold and 150 t silver. Evidence of similar precious metal mineralization at the Yucca Mountain site may lead to mining or exploratory drilling in the future, compromising the security of the repository. The authors believe that most of the pyrite encountered by drilling at Yucca Mountain was introduced as pyroclastic ejecta, rather than by in situ hydrothermal activity. Pyritic ejecta in ash-flow tuff are not reported in the literature, but there is no reason to believe that the Yucca Mountain occurrence is unique. The pyritic ejecta are considered by us to be part of a preexisting hydrothermal system that was partially or wholly destroyed during eruption of the tuff units. Because it was introduced as ejecta in tuff units that occur at depths of about 1,000 m, such pyrite does not constitute evidence of shallow mineralization at the proposed repository site; however, the pyrite may be evidence for mineralization deep beneath Yucca Mountain or as much as tens of kilometers from it

  11. Evaluation of tuff as a medium for a nucolear waste repository: interim status report on the properties of tuff

    International Nuclear Information System (INIS)

    Johnstone, J.K.; Wolfsberg, K.

    1980-07-01

    This report is the second in a series of summary briefings to the National Academy of Science's (NAS) Committee on Radioactive Waste Management dealing with feasibility of disposal of heat-producing radioactive waste in silicic tuff. The interim status of studies of tuff properties determined on samples obtained from Yucca Mountain and Rainier Mesa (G-tunnel) located on the Nevada Test Site (NTS) are discussed. In particular, progress is described on resolving issues identified during the first briefing to the NAS which include behavior of water in tuff when heated, the effect of the presence or absence of water and joints on the thermal/physical properties of tuff and the detailed/complex sorptive properties of highly altered and unaltered tuff. Initial correlations of thermal/physical and sorptive properties with the highly variable porosity and mineralogy are described. Three in-situ, at-depth field experiments, one nearly completed and two just getting underway are described. In particular, the current status of mineralogy and petrology, geochemistry, thermal and mechanical, radiation effects and water behavior studies are described. The goals and initial results of a Mine Design Working Group are discussed. Regional factors such as seismicity, volcanism and hydrology are not discussed

  12. Petrology of tuff units from the J-13 drill site, Jackass Flats, Nevada

    International Nuclear Information System (INIS)

    Heiken, G.H.; Bevier, M.L.

    1979-01-01

    The J-13 drill hole, located in Jackass Flats, Nevada Test Site, has penetrated 125 m of alluvium and 932 m of tuff. Most of the tuff deposits consist of welded tuffs; glass phases in the tuffs have been replaced by authigenic minerals, mainly K-feldspar, silica, and zeolites. The zonation of authigenic minerals, with depth, indictes that alteration of glass phases and filling of vugs occurred during welding and compaction of tuff units soon after deposition and by interaction with groundwater. Zonation of authigenic minerals in tuff deposits at Jackass Flats is similar to mineral zonation in tuffs elsewhere at the Nevada Test Site and in tuff deposits of west Texas. All appear to have been developed by leaching of glass phases and deposition of authigenic minerals in open hydrologic systems. 10 figures, 38 tables

  13. G-Tunnel welded tuff mining experiment data summary

    International Nuclear Information System (INIS)

    Zimmerman, R.M.; Bellman, R.A. Jr.; Mann, K.L.; Zerga, D.P.; Fowler, M.

    1990-03-01

    Designers and analysts of radioactive waste repositories must be ably to predict the mechanical behavior of the host rock. Sandia National Laboratories elected to conduct a mine-by in welded tuff so that predictive-type information could be obtained regarding the response of the rock to a drill and blast excavation process, where smooth blasting techniques were used. Included in the study were evaluations of and recommendations for various measurement systems that might be used in future mine by efforts. This report summarizes all of the data obtained in the welded tuff mining experiment. 6 refs., 29 figs., 12 tabs

  14. Durable terrestrial bedrock predicts submarine canyon formation

    Science.gov (United States)

    Smith, Elliot; Finnegan, Noah J.; Mueller, Erich R.; Best, Rebecca J.

    2017-01-01

    Though submarine canyons are first-order topographic features of Earth, the processes responsible for their occurrence remain poorly understood. Potentially analogous studies of terrestrial rivers show that the flux and caliber of transported bedload are significant controls on bedrock incision. Here we hypothesize that coarse sediment load could exert a similar role in the formation of submarine canyons. We conducted a comprehensive empirical analysis of canyon occurrence along the West Coast of the contiguous United States which indicates that submarine canyon occurrence is best predicted by the occurrence of durable crystalline bedrock in adjacent terrestrial catchments. Canyon occurrence is also predicted by the flux of bed sediment to shore from terrestrial streams. Surprisingly, no significant correlation was observed between canyon occurrence and the slope or width of the continental shelf. These findings suggest that canyon incision is promoted by greater yields of durable terrestrial clasts to the shore.

  15. Submarine canyons off Madras Coast

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    Submarine canyons off the coast of Madras, Tamil Nadu, India were studied during cruise of @iINS Kistna@@ as part of the IIOE programme They consist of hill-like projections and V-shaped valleys Their other features are also reported...

  16. Mineralogy, origin and commercial value of the zeolite-rich tuffs in the Petrota-Pentalofos area, Evros County, Greece

    Directory of Open Access Journals (Sweden)

    Walsh, J. N.

    1998-04-01

    Full Text Available The zeolite-rich tuffs of the Petrota-Pentalofos area were deposited in the Arrestees Basin during the Eocene. They are up to 100 m thick and extend more than 15 Km in a long axis. Most of the outcrops consist of frequent alternations of very fine grained tuff with pumice and lapel tuffs, the latter containing detrital fragments of the Mesozoic substrate of the basin. X-ray Diffraction, Scanning Electron Microscopy and light microscopy analysis on quarry and borehole samples has shown that the tuffs are composed mainly of clinoptilolite and minor cristobalite, with a small proportion of detrital constituents (quartz, mica-schist and pyrogenic crystals (feldspars, quartz, biotite. Minor amounts of mordenite randomly occur in some of the northern outcrops, closer to the occurrences of lava. ICP-AES chemical analysis of the tuffs gives evidence that the original magmas were of quartz-latite composition. The tuffs rest on pre-Cenozoic metamorphic basement and pass gradationally upwards into sandstone and limestone. Evidence is given for deposition of the tuffs in a supra to infra-littoral environment. The zeolitic tuffs originated as epiclastic volcanic sediments, transported by water from the source of the eruption. The transformation of the volcanic glass of the tuffs to zeolite and cristobalite has taken place by meteoric waters in an open hydrological system existed during the Tertiary. The zeolitic rocks are currently being exploited as an animal feed supplement.Las tobas ricas en cebollitas del área de Petrota-Pentalofos se depositaron en la cuenca de Orejitas durante el Doceno. Alcanzan 100 m de potencia y superan los 15 km de extensión longitudinal. La mayoría de los afloramientos consisten en alternancias de toba de grano muy fino y toba de pómez y lapilli con fragmentos detritos del sustrato Mesozoico de la cuenca. Análisis por difamación de rayos X, microscopía electrónica de barrido y microscopía óptica en muestras de mano y de

  17. Mineralogy, geochemistry and petrogenesis of volcanic tuffs from Ataraws, Jordan

    International Nuclear Information System (INIS)

    Al-Fugha, H.

    1997-01-01

    Magistracy are common in tuff and paralytic's materials of Pleistocene age in western Jordan. The dominant phases are olivine, augite, plagioclase, magnetite and ilmenite. Chemical analysis of the whole rocks samples indicate alkali olivine magma origin. Low concentration of Li and Rb in Tuff samples are used as an argument against the contamination of the basaltic magma during its journey to the surface. The Mg O and mg- values (Mg/Mg+Fe 2+ ) in samples from volcano exhibit different degrees of fractionation, which are indicated by the varying concentrations of incompatible trace elements (Ba, Rb, Sr). The thermometric evacuation of tuff formation by using pyroxenes thermometers revealed a temperature range between 1022-1083 deg. and pressure of 5-10 K bars. The low Mg-ratio (Mg/Mg+Fe 2+ ) is due to fractional crystallization of olivine and pyroxene in tuff samples. The variation of incompatible elements imply derivation from a peridotite source in the upper mantle with low degree of melting (<20%).The volcanic activity took place in phases corresponding to rifting sinistral displacement along the Jordan Rift. (author). 11 refs., 6 tabs, 6 figs

  18. Geomorphic process fingerprints in submarine canyons

    Science.gov (United States)

    Brothers, Daniel S.; ten Brink, Uri S.; Andrews, Brian D.; Chaytor, Jason D.; Twichell, David C.

    2013-01-01

    Submarine canyons are common features of continental margins worldwide. They are conduits that funnel vast quantities of sediment from the continents to the deep sea. Though it is known that submarine canyons form primarily from erosion induced by submarine sediment flows, we currently lack quantitative, empirically based expressions that describe the morphology of submarine canyon networks. Multibeam bathymetry data along the entire passive US Atlantic margin (USAM) and along the active central California margin near Monterey Bay provide an opportunity to examine the fine-scale morphology of 171 slope-sourced canyons. Log–log regression analyses of canyon thalweg gradient (S) versus up-canyon catchment area (A) are used to examine linkages between morphological domains and the generation and evolution of submarine sediment flows. For example, canyon reaches of the upper continental slope are characterized by steep, linear and/or convex longitudinal profiles, whereas reaches farther down canyon have distinctly concave longitudinal profiles. The transition between these geomorphic domains is inferred to represent the downslope transformation of debris flows into erosive, canyon-flushing turbidity flows. Over geologic timescales this process appears to leave behind a predictable geomorphic fingerprint that is dependent on the catchment area of the canyon head. Catchment area, in turn, may be a proxy for the volume of sediment released during geomorphically significant failures along the upper continental slope. Focused studies of slope-sourced submarine canyons may provide new insights into the relationships between fine-scale canyon morphology and down-canyon changes in sediment flow dynamics.

  19. Interstratified arkosic and volcanic rocks of the Miocene Spanish Canyon Formation, Alvord Mountain area, California: descriptions and interpretations

    Science.gov (United States)

    Buesch, David C.

    2014-01-01

    The Spanish Canyon Foundation in the Alvord Mountain area, California, varies from about 50 to 120 m thick and records the interstratification of arkosic sandstone and conglomerate with tuffaceous deposits and lava flows. In the lower third of the formation, arkosic sandstone and conglomerate are interstratified with tuffaceous deposits. Some tuffs might have been deposited as primary, nonwelded to partially welded ignimbrites or fallout tephra. Many of the tuffaceous deposits represent redeposited material that formed tuffaceous sandstone, and many of these deposits contain arkosic grains that represent mixing of different source matieral. Arkosic sandstone, and especially conglomerate (some with maximum clast lengths up to 1 m), represent intermittent incursions of coarser plutoniclastic fan deposits into other finer grained and mostly volcaniclastic basin deposits. After deposition of the 18.78 Ma Peach Spring Tuff, the amount of tuffaceous material decreased. The upper two-thirds of the formation has arkosic sandstone and conglomerate interstratified with two olivine basalt lave flows. locally, conglomerate clasts in this part of the section have maximum lengths up to 1 m. Many tuffaceous and arkosic sandstone beds of the Spanish Canyon Formation have tabular to broad (low-relief) lenticular geometry, and locally, some arkosic conglomerate fills channels as much as 1.5 m deep. These bedforms are consistent with deposition in medial to distal alluvial-fan or fluvial environments; some finer-grained deposits might have formed in lacustrine environments.

  20. Marble Canyon spring sampling investigation

    International Nuclear Information System (INIS)

    McCulley, B.

    1985-10-01

    The Mississippian Leadville Limestone is the most permeable formation in the lower hydrostratigraphic unit underlying the salt beds of the Paradox Formation in Gibson Dome, Paradox Basin, Utah, which is being considered as a potential nuclear waste repository site. The closest downgradient outcrop of the Mississippian limestone is along the Colorado River in Marble Canyon, Arizona. This report describes the sampling and interpretation of springs in that area to assess the relative contribution of Gibson Dome-type Leadville Limestone ground water to that spring discharge. The high-volume (hundreds of liters per second or thousands of gallons per minute) springs discharging from fault zones in Marble Canyon are mixtures of water recharged west of the Colorado River on the Kaibab Plateau and east of the river in the Kaiparowits basin. No component of Gibson Dome-type Leadville Limestone ground water is evident in major and trace element chemistry or isotopic composition of the Marble Canyon Springs. A low-volume (0.3 liters per second or 5 gallons per minute) spring with some chemical and isotopic characteristics of Gibson Dome-type Leadville Limestone water diluted by Kaiparowits basin-type water issues from a travertine mound in the Bright Angel Shale on the Little Colorado River. However, the stable isotopic composition and bromide levels of that spring discharge, in addition to probable ground-water flow paths, contradict the dilution hypothesis

  1. Preliminary report on the geology and hydrology of Mortandad Canyon near Los Alamos, New Mexico, with reference to disposal of liquid low-level radioactive waste

    Science.gov (United States)

    Baltz, E.H.; Abrahams, J.H.; Purtyman, W.D.

    1963-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Atomic Energy Commission and the Los Alamos Scientific Laboratory, selected the upper part of Mortandad Canyon near Los Alamos, New Mexico for a site for disposal of treated liquid low-level radioactive waste. This report summarizes the part of a study of the geology and hydrology that was done from October 1960 through June 1961. Additional work is being continued. Mortandad Canyon is a narrow east-southeast-trending canyon about 9? miles long that heads on the central part of the Pajarito Plateau at an altitude of about 7,340 feet. The canyon is tributary to the Rio Grande. The drainage area of the part of Mortandad Canyon that was investigated is about 2 square miles, and the total drainage area is about 4.9 square miles. The Pajarito Plateau is capped by the Bandelier Tuff of Pleistocene age. Mortandad Canyon is cut in the Bandelier, and alluvium covers the floor of the canyon to depths ranging from less than 1 foot to as much as 100 feet. The Bandelier is underlain by silt, sand, conglomerate, and interbedded basalt of the Santa Fe Group of Miocene, Pliocene, and Pleistocene(?) age. Some ground water is perched in the alluvium in the canyon; however, the top of the main aquifer is in the Santa Fe Group at a depth of about 990 feet below the canyon floor. Joints in the Bandelier Tuff probably were caused by shrinkage of the tuff during cooling. The joints range in width from hairline cracks to fissures several inches wide. Water can infiltrate along the open joints where the Bandelier is at the surface; however, soil, alluvial fill, and autochthonous clay inhibit infiltration on the tops of mesas and probably in the alluvium-floored canyons also. Thirty-three test holes, each less than 100 feet deep, were drilled in 10 lies across Mortandad Canyon from the western margin of the study area to just west of the Los Alamos-Santa Fe County line. Ten of the holes were cased for observation wells to measure

  2. Pena Blanca uranium deposits and ash-flow tuffs relationship

    International Nuclear Information System (INIS)

    Magonthier, M.

    1987-01-01

    The Pena Blanca uranium deposits (Chihuahua, Mexico) are associated with a Tertiary sequence of ash-flow tuffs. Stratigraphic control is dominant and uranium mineralization occurs in stratiform and fracture-controlled deposits within 44 My-old units: Nopal Rhyolite and Escuadra Rhyolite. These units consist of highly vapor-phase crystallized ash-flow tuffs. They contain sanidine, quartz and granophyric phenocrysts, and minor ferromagnesian silicates. Nopal and Escuadra units are high-silica alkali-rich rhyolites that have a primary potassic character. The trace-element chemistry shows high concentrations in U-Th-Rb-Cs and low contents in Ba-Sr-Eu. These chemical properties imply a genetic relationship between deposits and host-units. The petrochemical study show that the Nopal Rhyolite and Escuadra Rhyolite are the source of U and of hydrothermal solutions [fr

  3. Modeling of flow through fractured tuff at Fran Ridge

    International Nuclear Information System (INIS)

    Eaton, R.R.; Ho, C.K.; Glass, R.J.; Nicholl, M.J.; Arnold, B.W.

    1996-01-01

    Numerical studies have modeled an infiltration experiment at Fran Ridge, using the TOUGH2 code, to aid in the selection of computational models for waste repository performance assessment. This study investigates the capabilities of TOUGH2 to simulate transient flows through highly fractured tuff, and provides a possible means of calibrating hydrologic parameters such as effective fracture aperture and fracture-matrix connectivity. Two distinctly different conceptual models were used in the TOUGH2 code, the dual permeability model and the equivalent continuum model. The field experiments involved the infiltration of dyed ponded water in highly fractured tuff. The infiltration observed in the experiment was subsequently modeled using Fran Ridge fracture frequencies, obtained during post-experiment site excavation. Comparison of the TOUGH2 results obtained using the two conceptual models gives insight into their relative strengths and weaknesses

  4. Biogas cleaning and upgrading with natural zeolites from tuffs.

    Science.gov (United States)

    Paolini, Valerio; Petracchini, Francesco; Guerriero, Ettore; Bencini, Alessandro; Drigo, Serena

    2016-01-01

    CO2 adsorption on synthetic zeolites has become a consolidated approach for biogas upgrading to biomethane. As an alternative to synthetic zeolites, tuff waste from building industry was investigated in this study: indeed, this material is available at a low price and contains a high fraction of natural zeolites. A selective adsorption of CO2 and H2S towards CH4 was confirmed, allowing to obtain a high-purity biomethane (CO2 biogas samples were used, and no significant effects due to biogas impurities (e.g. humidity, dust, moisture, etc.) were observed. Thermal and vacuum regenerations were also optimized and confirmed to be possible, without significant variations in efficiency. Hence, natural zeolites from tuffs may successfully be used in a pressure/vacuum swing adsorption process.

  5. Fracture coatings in Topopah Spring Tuff along drill hole wash

    International Nuclear Information System (INIS)

    Carlos, B.A.; Chipera, S.J.; Bish, D.L.

    1994-01-01

    Fracture-lining minerals are being studied as part of site characterization to determine the suitability of Yucca Mountain, Nevada as a potential high level nuclear waste repository. Fracture coatings in the Paintbrush Group provide information on potential flow paths above the water table both toward and away from the potential repository and provide information on the distribution of fracture-lining minerals needed to model thermal effects of waste emplacement. Fracture coatings within the predominantly non-zeolitic Paintbrush Group vary both with depth and laterally across Yucca Mountain, whereas fracture coatings in tuffs below the Paintbrush Group are related to the mineralogy of the tuffs and follow a consistent pattern of distribution with predominantly quartz, calcite, and manganese oxides in the devitrified intervals and mordenite and clinoptilolite in the zeolitic intervals. The zeolites stellerite and heulandite are more abundant in fractures in the Topopah Spring Tuff in drill holes USW G-1 and UE-25 a number-sign l, located along Drill Hole Wash (at the northern end of Yucca Mountain) than in core from other parts of Yucca Mountain. Buesch et al. (2) present evidence for a complex fault system along Drill Hole Wash. To investigate the possibility that the abundant fracture-lining zeolites in USW G-1 and UE-25 a number-sign 1 are related to the Drill Hole Wash fault, the Topopah Spring Tuff was examined in drill cores from USW UZ-14, USW G-1, USW NRG-7/7a, and UE-25 a number-sign l

  6. Low temperature spent fuel oxidation under tuff repository conditions

    International Nuclear Information System (INIS)

    Einziger, R.E.; Woodley, R.E.

    1985-01-01

    The Nevada Nuclear Waste Storage Investigations Project is studying the suitability of tuffaceous rocks at Yucca Mountain, Nye County, Nevada, for high level waste disposal. The oxidation state of LWR spent fuel in a tuff repository may be a significant factor in determining its ability to inhibit radionuclide migration. Long term exposure at low temperatures to the moist air expected in a tuff repository is expected to increase the oxidation state of the fuel. A program is underway to determine the spent fuel oxidation mechanisms which might be active in a tuff repository. Initial work involves a series of TGA experiments to determine the effectiveness of the technique and to obtain preliminary oxidation data. Tests were run at 200 0 C and 225 0 C for as long as 720 hours. Grain boundary diffusion appears to open up a greater surface area for oxidation prior to onset of bulk diffusion. Temperature strongly influences the oxidation rates. The effect of moisture is small but readily measurable. 25 refs., 7 figs., 4 tabs

  7. Performance testing of waste forms in a tuff environment

    International Nuclear Information System (INIS)

    Oversby, V.M.

    1983-11-01

    This paper describes experimental work conducted to establish the chemical composition of water which will have reacted with Topopah Spring Member tuff prior to contact with waste packages. The experimental program to determine the behavior of spent fuel and borosilicate glass in the presence of this water is then described. Preliminary results of experiments using spent fuel segments with defects in the Zircaloy cladding are presented. Some results from parametric testing of a borosilicate glass with tuff and 304L stainless steel are also discussed. Experiments conducted using Topopah Spring tuff and J-13 well water have been conducted to provide an estimate of the post-emplacement environment for waste packages in a repository at Yucca Mountain. The results show that emplacement of waste packages should cause only small changes in the water chemistry and rock mineralogy. The changes in environment should not have any detrimental effects on the performance of metal barriers or waste forms. The NNWSI waste form testing program has provided preliminary results related to the release rate of radionuclides from the waste package. Those results indicate that release rates from both spent fuel and borosilicate glass should be below 1 part in 10 5 per year. Future testing will be directed toward making release rate testing more closely relevant to site specific conditions. 17 references, 7 figures

  8. Repository site data report for unsaturated tuff, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Tien, P.L.; Updegraff, C.D.; Siegel, M.D.; Wahi, K.K.; Guzowski, R.V.

    1985-11-01

    The US Department of Energy is currently considering the thick sequences of unsaturated, fractured tuff at Yucca Mountain, on the southwestern boundary of the Nevada Test Site, as a possible candidate host rock for a nuclear-waste repository. Yucca Mountain is in one of the most arid areas in the United States. The site is within the south-central part of the Great Basin section of the Basin and Range physiographic province and is located near a number of silicic calderas of Tertiary age. Although localized zones of seismic activity are common throughout the province, and faults are present at Yucca Mountain, the site itself is basically aseismic. No data are available on the composition of ground water in the unsaturated zone at Yucca Mountain. It has been suggested that the composition is bounded by the compositions of water from wells USW-H3, UE25p-1, J-13, and snow or rain. There are relatively few data available from Yucca Mountain on the moisture content and saturation, hydraulic conductivity, and characteristic curves of the unsaturated zone. The available literature on thermomechanical properties of tuff does not always distinguish between data from the saturated zone and data from the unsaturated zone. Geochemical, hydrologic, and thermomechanical data available on the unsaturated tuffs of Yucca Mountain are tabulated in this report. Where the data are very sparse, they have been supplemented by data from the saturated zone or from areas other than Yucca Mountain. 316 refs., 58 figs., 37 tabs

  9. Measuring and Modeling Flow in Welded Fractured Tuffs

    International Nuclear Information System (INIS)

    R. Salve; C. Doughty; J.S. Wang

    2001-01-01

    We have carried out a series of in situ liquid-release experiments in conjunction with a numerical modeling study to examine the effect of the rock matrix on liquid flow and transport occurring primarily through the fracture network. Field experiments were conducted in the highly fractured Topopah Spring welded tuff at a site accessed from the Exploratory Studies Facility (ESFS), an underground laboratory in the unsaturated zone at Yucca Mountain, Nevada. During the experiment, wetting-front movement, flow-field evolution, and drainage of fracture flow paths were evaluated. Modeling was used to aid in experimental design, predict experimental results, and study the physical processes accompanying liquid flow through unsaturated fractured welded tuff. Field experiments and modeling suggest that it may not be sufficient to conceptualize the fractured tuff as consisting of a single network of high-permeability fractures embedded in a low-permeability matrix. The need to include a secondary fracture network is demonstrated by comparison to the liquid flow observed in the field

  10. Repository site data report for unsaturated tuff, Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Tien, P.L.; Updegraff, C.D.; Siegel, M.D.; Wahi, K.K.; Guzowski, R.V.

    1985-11-01

    The US Department of Energy is currently considering the thick sequences of unsaturated, fractured tuff at Yucca Mountain, on the southwestern boundary of the Nevada Test Site, as a possible candidate host rock for a nuclear-waste repository. Yucca Mountain is in one of the most arid areas in the United States. The site is within the south-central part of the Great Basin section of the Basin and Range physiographic province and is located near a number of silicic calderas of Tertiary age. Although localized zones of seismic activity are common throughout the province, and faults are present at Yucca Mountain, the site itself is basically aseismic. No data are available on the composition of ground water in the unsaturated zone at Yucca Mountain. It has been suggested that the composition is bounded by the compositions of water from wells USW-H3, UE25p-1, J-13, and snow or rain. There are relatively few data available from Yucca Mountain on the moisture content and saturation, hydraulic conductivity, and characteristic curves of the unsaturated zone. The available literature on thermomechanical properties of tuff does not always distinguish between data from the saturated zone and data from the unsaturated zone. Geochemical, hydrologic, and thermomechanical data available on the unsaturated tuffs of Yucca Mountain are tabulated in this report. Where the data are very sparse, they have been supplemented by data from the saturated zone or from areas other than Yucca Mountain. 316 refs., 58 figs., 37 tabs.

  11. 78 FR 7775 - Boulder Canyon Project

    Science.gov (United States)

    2013-02-04

    ... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area...), is proposing an adjustment to the Boulder Canyon Project (BCP) electric service base charge and rates... subsequent laws, particularly section 9(c) of the Reclamation Project Act of 1939 (43 U.S.C. 485h(c)); and...

  12. 77 FR 2533 - Boulder Canyon Project

    Science.gov (United States)

    2012-01-18

    ... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area...), is proposing an adjustment to the Boulder Canyon Project (BCP) electric service base charge and rates...) of the Reclamation Project Act of 1939 (43 U.S.C. 485h(c)); and other acts that specifically apply to...

  13. 76 FR 56430 - Boulder Canyon Project

    Science.gov (United States)

    2011-09-13

    ... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Project (BCP) electric service provided by the Western Area Power Administration (Western). The Rates will... by the Boulder Canyon Project Act (45 Stat. 1057, December 21, 1928), sits on the Colorado River...

  14. 76 FR 8359 - Boulder Canyon Project

    Science.gov (United States)

    2011-02-14

    ... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Western Area Power Administration (Western) is proposing an adjustment to the Boulder Canyon Project (BCP... Reclamation Project Act of 1939 (43 U.S.C. 485h(c)), and other acts that specifically apply to the project...

  15. Grand Canyon Monitoring and Research Center

    Science.gov (United States)

    Hamill, John F.

    2009-01-01

    The Grand Canyon of the Colorado River, one of the world's most spectacular gorges, is a premier U.S. National Park and a World Heritage Site. The canyon supports a diverse array of distinctive plants and animals and contains cultural resources significant to the region's Native Americans. About 15 miles upstream of Grand Canyon National Park sits Glen Canyon Dam, completed in 1963, which created Lake Powell. The dam provides hydroelectric power for 200 wholesale customers in six western States, but it has also altered the Colorado River's flow, temperature, and sediment-carrying capacity. Over time this has resulted in beach erosion, invasion and expansion of nonnative species, and losses of native fish. Public concern about the effects of Glen Canyon Dam operations prompted the passage of the Grand Canyon Protection Act of 1992, which directs the Secretary of the Interior to operate the dam 'to protect, mitigate adverse impacts to, and improve values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established...' This legislation also required the creation of a long-term monitoring and research program to provide information that could inform decisions related to dam operations and protection of downstream resources.

  16. Environmental assessment: Davis Canyon site, Utah

    Energy Technology Data Exchange (ETDEWEB)

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high- level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of the five sites suitable for characterization.

  17. Environmental assessment: Davis Canyon site, Utah

    Energy Technology Data Exchange (ETDEWEB)

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considering for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization.

  18. Environmental assessment: Davis Canyon site, Utah

    International Nuclear Information System (INIS)

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considering for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization

  19. Environmental assessment: Davis Canyon site, Utah

    International Nuclear Information System (INIS)

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high- level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of the five sites suitable for characterization

  20. Bell Canyon test summary report

    International Nuclear Information System (INIS)

    Christensen, C.L.; Peterson, E.W.

    1981-04-01

    The Bell Canyon Test was an in situ evaluation of the ability of a cement grout plug to seal boreholes. It consisted of a 2-m-long, 20-cm-diameter grout plug in an anhydrite formation at a depth of 1370 m, directly above an aquifer that provided a 12.4 MPa (1800 psi) differential pressure. The aquifer had a production capability of 38,000 l/day (240 bbl/day, 10 4 gal/day). The observed leakage after plug installation was 0.6 l/day, which is equivalent to a 50 microdarcy flow path assuming all flow occurred through the plug cross-sectional area. Laboratory results and analysis of field data indicate that the bulk of the flow occurred through a microstructure at the interface between the plug and the host rock. The Bell Canyon Test demonstrated that a plug could be formulated, emplaced, and tested under actual conditions and provide acceptable performance. When these results are related to the WIPP performance assessment models, they provide additional confidence that borehole plugging can be accomplished satisfactorily. The Bell Canyon results can also be used as basis for future activities in the generic repository sealing program for similar emplacements and performance assessment evaluations. If the observed leakage rates are not acceptable at other sites, the BCT results would indicate that the first step in improving such emplacements should deal with improved bonding of the plug to the rock at these sites. The results obtained from the BCT, when coupled with results from long-term durability assessments, form a plug performance data basis for repository designers at other proposed waste repository sites

  1. H-Canyon Recovery Crawler

    Energy Technology Data Exchange (ETDEWEB)

    Kriikku, E. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hera, K. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Marzolf, A. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Phillips, M. H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-08-01

    The Nuclear Material Disposition Project group asked the Savannah River National Lab (SRNL) Research and Development Engineering (R&DE) department to help procure, test, and deploy a remote crawler to recover the 2014 Inspection Crawler (IC) that tipped over in the H-Canyon Air Exhaust Tunnel. R&DE wrote a Procurement Specification for a Recovery Crawler (RC) and SRNS Procurement Department awarded the contract to Power Equipment Manufacturing Inc. (PEM). The PEM RC was based on their standard sewer inspection crawler with custom arms and forks added to the front. The arms and forks would be used to upright the 2014 Inspection Crawler. PEM delivered the RC and associated cable reel, 2014 Inspection Crawler mockup, and manuals in late April 2015. R&DE and the team tested the crawler in May of 2015 and made modifications based on test results and Savannah River Site (SRS) requirements. R&DE delivered the RC to H-Area at the end of May. The team deployed the RC on June 9, 10, and 11, 2015 in the H-Canyon Air Exhaust Tunnel. The RC struggled with some obstacles in the tunnel, but eventually made it to the IC. The team spent approximately five hours working to upright the IC and eventually got it on its wheels. The IC travelled approximately 20 feet and struggled to drive over debris on the air tunnel floor. Unfortunately the IC tripped over trying to pass this obstacle. The team decided to leave the IC in this location and inspect the tunnel with the RC. The RC passed the IC and inspected the tunnel as it travelled toward H-Canyon. The team turned the RC around when it was about 20 feet from the H-Canyon crossover tunnel. From that point, the team drove the RC past the manway towards the new sand filter and stopped approximately 20 feet from the new sand filter. The team removed the RC from the tunnel, decontaminated the RC, and stored it the manway building, 294-2H. The RC deployment confirmed the IC was not in a condition to perform useful tunnel inspections and

  2. Environmental assessment overview, Davis Canyon site, Utah

    International Nuclear Information System (INIS)

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization. 3 figs

  3. Pretest thermal analysis of the Tuff Water Migration/In-Situ Heater Experiment

    International Nuclear Information System (INIS)

    Bulmer, B.M.

    1980-02-01

    This report describes the pretest thermal analysis for the Tuff Water Migration/In-Situ Heater Experiment to be conducted in welded tuff in G-tunnel, Nevada Test Site. The parametric thermal modeling considers variable boiling temperature, tuff thermal conductivity, tuff emissivity, and heater operating power. For nominal tuff properties, some near field boiling is predicted for realistic operating power. However, the extent of boiling will be strongly determined by the ambient (100% water saturated) rock thermal conductivity. In addition, the thermal response of the heater and of the tuff within the dry-out zone (i.e., bounded by boiling isotherm) is dependent on the temperature variation of rock conductivity as well as the extent of induced boiling

  4. Prehistoric deforestation at Chaco Canyon?

    Science.gov (United States)

    Wills, W H; Drake, Brandon L; Dorshow, Wetherbee B

    2014-08-12

    Ancient societies are often used to illustrate the potential problems stemming from unsustainable land-use practices because the past seems rife with examples of sociopolitical "collapse" associated with the exhaustion of finite resources. Just as frequently, and typically in response to such presentations, archaeologists and other specialists caution against seeking simple cause-and effect-relationships in the complex data that comprise the archaeological record. In this study we examine the famous case of Chaco Canyon, New Mexico, during the Bonito Phase (ca. AD 860-1140), which has become a prominent popular illustration of ecological and social catastrophe attributed to deforestation. We conclude that there is no substantive evidence for deforestation at Chaco and no obvious indications that the depopulation of the canyon in the 13th century was caused by any specific cultural practices or natural events. Clearly there was a reason why these farming people eventually moved elsewhere, but the archaeological record has not yet produced compelling empirical evidence for what that reason might have been. Until such evidence appears, the legacy of Ancestral Pueblo society in Chaco should not be used as a cautionary story about socioeconomic failures in the modern world.

  5. Carbon transport in Monterey Submarine Canyon

    Science.gov (United States)

    Barry, J.; Paull, C. K.; Xu, J. P.; Clare, M. A.; Gales, J. A.; Buck, K. R.; Lovera, C.; Gwiazda, R.; Maier, K. L.; McGann, M.; Parsons, D. R.; Simmons, S.; Rosenberger, K. J.; Talling, P. J.

    2017-12-01

    Submarine canyons are important conduits for sediment transport from continental margins to the abyss, but the rate, volume, and time scales of material transport have been measured only rarely. Using moorings with current meters, sediment traps (10 m above bottom) and optical backscatter sensors, we measured near-bottom currents, suspended sediment concentrations, and sediment properties at 1300 m depth in Monterey Canyon and at a non-canyon location on the continental slope at the same depth. Flow and water column backscatter were used to characterize "ambient" conditions when tidal currents dominated the flow field, and occasional "sediment transport events" when anomalously high down-canyon flow with sediment-laden waters arrived at the canyon mooring. The ambient sediment flux measured in sediment traps in Monterey Canyon was 350 times greater than measured at the non-canyon location. Although the organic carbon content of the canyon sediment flux during ambient periods was low (1.8 %C) compared to the slope location (4.9 %C), the ambient carbon transport in the canyon was 130 times greater than at the non-canyon site. Material fluxes during sediment transport events were difficult to measure owing to clogging of sediment traps, but minimal estimates indicate that mass transport during events exceeds ambient sediment fluxes through the canyon by nearly 3 orders of magnitude, while carbon transport is 380 times greater. Estimates of the instantaneous and cumulative flux of sediment and carbon from currents, backscatter, and sediment properties indicated that: 1) net flux is down-canyon, 2) flux is dominated by sediment transport events, and 3) organic carbon flux through 1300 m in Monterey Canyon was ca. 1500 MT C per year. The injection of 1500 MTCy-1 into the deep-sea represents ca. 260 km2 of the sediment C flux measured at the continental slope station (5.8 gCm-2y-1) and is sufficient to support a benthic community carbon demand of 5 gCm-2y-1 over 300 km2.

  6. Observation of time dependent dispersion in laboratory scale experiments with intact tuff

    International Nuclear Information System (INIS)

    Rundberg, R.S.; Triay, I.R.; Ott, M.A.; Mitchell, A.J.

    1989-01-01

    The migration of radionuclides through intact tuff was studied using tuff from Yucca Mountain, Nevada. The tuff samples were both highly zeolitized ash-fall tuff from the Calico Hills and densely welded devitrified tuff from the Topopah Springs member of the Paintbrush tuff. Tritiated water and pertechnetate were used as conservative tracers. The sorbing tracers 85 Sr, 137 Cs, and 133 Ba were used with the devitrified tuff only. Greater tailing in the elution curves of the densely welded tuff samples was observed that could be fit by adjusting the dispersion coefficient in the conventional Advection Dispersion Equation, ADE. The curves could be fit using time dependent dispersion as was previously observed for sediments and alluvium by Dieulin, Matheron, and de Marsily. The peak of strontium concentration was expected to arrive after 1.5 years based on the conventional ADE and assuming a linear K d of 26 ml/g. The observed elution had significant strontium in the first sample taken at 2 weeks after injection. The peak in the strontium elution occurred at 5 weeks. The correct arrival time for the strontium peak was achieved using a one dimensional analytic solution with time dependent dispersion. The dispersion coefficient as a function of time used to fit the conservative tracers was found to predict the peak arrival of the sorbing tracers. The K d used was the K d determined by the batch method on crushed tuff. 23 refs., 9 figs., 2 tabs

  7. Effects of mineralogy on sorption of strontium and cesium onto Calico Hills Tuff

    International Nuclear Information System (INIS)

    Meyer, R.E.; Arnold, W.D.; Case, F.I.; O'Kelley, G.D.; Land, J.F.

    1990-04-01

    The sorption properties of tuff formations at the proposed site for the high-level nuclear waste repository at Yucca Mountain, Nevada, have been extensively studied. Sorption and desorption measurements were made of strontium and cesium onto clinoptilolite and Calico Hills Tuff. The object was to see whether there was a correlation between sorption of strontium and cesium onto Calico Hills Tuff and the sorption of strontium and cesium onto clinoptilolite based on the content of clinoptilolite in the Calico Hills Tuff. 13 refs., 10 figs., 6 tabs

  8. Flow dynamics around downwelling submarine canyons

    Directory of Open Access Journals (Sweden)

    J. M. Spurgin

    2014-10-01

    Full Text Available Flow dynamics around a downwelling submarine canyon were analysed with the Massachusetts Institute of Technology general circulation model. Blanes Canyon (northwestern Mediterranean was used for topographic and initial forcing conditions. Fourteen scenarios were modelled with varying forcing conditions. Rossby and Burger numbers were used to determine the significance of Coriolis acceleration and stratification (respectively and their impacts on flow dynamics. A new non-dimensional parameter (χ was introduced to determine the significance of vertical variations in stratification. Some simulations do see brief periods of upwards displacement of water during the 10-day model period; however, the presence of the submarine canyon is found to enhance downwards advection of density in all model scenarios. High Burger numbers lead to negative vorticity and a trapped anticyclonic eddy within the canyon, as well as an increased density anomaly. Low Burger numbers lead to positive vorticity, cyclonic circulation, and weaker density anomalies. Vertical variations in stratification affect zonal jet placement. Under the same forcing conditions, the zonal jet is pushed offshore in more uniformly stratified domains. The offshore jet location generates upwards density advection away from the canyon, while onshore jets generate downwards density advection everywhere within the model domain. Increasing Rossby values across the canyon axis, as well as decreasing Burger values, increase negative vertical flux at shelf break depth (150 m. Increasing Rossby numbers lead to stronger downwards advection of a passive tracer (nitrate, as well as stronger vorticity within the canyon. Results from previous studies are explained within this new dynamic framework.

  9. Street canyon aerosol pollutant transport measurements.

    Science.gov (United States)

    Longley, I D; Gallagher, M W; Dorsey, J R; Flynn, M; Bower, K N; Allan, J D

    2004-12-01

    Current understanding of dispersion in street canyons is largely derived from relatively simple dispersion models. Such models are increasingly used in planning and regulation capacities but are based upon a limited understanding of the transport of substances within a real canyon. In recent years, some efforts have been made to numerically model localised flow in idealised canyons (e.g., J. Appl. Meteorol. 38 (1999) 1576-89) and stepped canyons (Assimakopoulos V. Numerical modelling of dispersion of atmospheric pollution in and above urban canopies. PhD thesis, Imperial College, London, 2001) but field studies in real canyons are rare. To further such an understanding, a measurement campaign has been conducted in an asymmetric street canyon with busy one-way traffic in central Manchester in northern England. The eddy correlation method was used to determine fluxes of size-segregated accumulation mode aerosol. Measurements of aerosol at a static location were made concurrently with measurements on a platform lift giving vertical profiles. Size-segregated measurements of ultrafine and coarse particle concentrations were also made simultaneously at various heights. In addition, a small mobile system was used to make measurements of turbulence at various pavement locations within the canyon. From this data, various features of turbulent transport and dispersion in the canyon will be presented. The concentration and the ventilation fluxes of vehicle-related aerosol pollutants from the canyon will be related to controlling factors. The results will also be compared with citywide ventilation data from a separate measurement campaign conducted above the urban canopy.

  10. Bond strength of cementitious borehole plugs in welded tuff

    International Nuclear Information System (INIS)

    Akgun, H.; Daemen, J.J.K.

    1991-02-01

    Axial loads on plugs or seals in an underground repository due to gas, water pressures and temperature changes induced subsequent to waste and plug emplacement lead to shear stresses at the plug/rock contact. Therefore, the bond between the plug and rock is a critical element for the design and effectiveness of plugs in boreholes, shafts or tunnels. This study includes a systematic investigation of the bond strength of cementitious borehole plugs in welded tuff. Analytical and numerical analysis of borehole plug-rock stress transfer mechanics is performed. The interface strength and deformation are studied as a function of Young's modulus ratio of plug and rock, plug length and rock cylinder outside-to-inside radius ratio. The tensile stresses in and near an axially loaded plug are analyzed. The frictional interface strength of an axially loaded borehole plug, the effect of axial stress and lateral external stress, and thermal effects are also analyzed. Implications for plug design are discussed. The main conclusion is a strong recommendation to design friction plugs in shafts, drifts, tunnels or boreholes with a minimum length to diameter ratio of four. Such a geometrical design will reduce tensile stresses in the plug and in the host rock to a level which should minimize the risk of long-term deterioration caused by excessive tensile stresses. Push-out tests have been used to determine the bond strength by applying an axial load to cement plugs emplaced in boreholes in welded tuff cylinders. A total of 130 push-out tests have been performed as a function of borehole size, plug length, temperature, and degree of saturation of the host tuff. The use of four different borehole radii enables evaluation of size effects. 119 refs., 42 figs., 20 tabs

  11. G-Tunnel Welded Tuff Mining experiment evaluations

    International Nuclear Information System (INIS)

    Zimmerman, R.M.; Bellman, R.A. Jr.; Mann, K.L.; Zerga, D.P.; Fowler, M.; Johnson, J.R.

    1988-12-01

    Designers and analysts of radioactive waste repositories must be able to predict the mechanical behavior of the host rock. Sandia National Laboratories elected to conduct a mine-by in welded tuff so that predictive-type information could be obtained regarding the response of the rock to a drill and blast excavation process, where smooth blasting techniques were used. This report describes the results of the mining processes and presents and discusses the rock mass responses to the mining and ground support activities. 37 refs., 20 figs., 7 tabs

  12. G-tunnel welded tuff mining experiment preparations

    International Nuclear Information System (INIS)

    Zimmerman, R.M.; Bellman, R.A. Jr.; Mann, K.L.; Zerga, D.P.

    1991-01-01

    Designers and analysts of radioactive waste repositories must be able to predict the mechanical behavior of the host rock. Sandia National Laboratories elected to conduct a mine-by in welded tuff so that predictive-type information could be obtained regarding the response of the rock to a drill and blast excavation process, where smooth blasting techniques were used. Included in the study were evaluations of and recommendations for various measurement systems that might be used in future mine-by efforts. This report summarizes the preparations leading to the recording of data. 17 refs., 27 figs., 5 tabs

  13. Diablo Canyon refueling outage program

    International Nuclear Information System (INIS)

    McLane, W.B.; Irving, T.L.

    1991-01-01

    Management of outages has become one of the most talked about subjects in the nuclear power industry in the past several years. Many utilities do not perform refueling outages very well or in the past have had some outages that they would not like to repeat and in some cases do not even like to think about. With the growing cost of energy and the demands placed on utilities to improve capacity factors, it is very easy for management to focus on shortening refueling outage durations as a prime objective in improving overall corporate performance. So it is with Pacific Gas and Electric Company and the Diablo Canyon power plant. A review of their refueling outage performance reflects a utility that is responding to the nuclear industry's call for improved outage performance

  14. Laboratory determined suction potential of Topopah Spring tuff at high temperatures

    International Nuclear Information System (INIS)

    Daily, W.; Lin, Wunan.

    1991-01-01

    The purpose of this work is to experimentally determine the capillary suction potential of Topopah Spring tuff from Yucca Mountain, Nye County, Nevada. This data can be used to help characterize the unsaturated hydraulic properties of the densely welded tuff at this site. 7 refs., 4 figs., 1 tab

  15. Stratigraphy of the Bandelier Tuff in the Pajarito Plateau. Applications to waste management

    International Nuclear Information System (INIS)

    Crowe, B.M.; Linn, G.W.; Heiken, G.; Bevier, M.L.

    1978-04-01

    The Bandelier Tuff within the Pajarito Plateau consists of a lower sequence of air-fall and ash-flow deposits (Otowi Member) disconformably overlain by an upper sequence of air-fall and ash-flow deposits (Tshirege Member). The ash-flow sequence of the Tshirege Member consists of three cooling units throughout much of the Pajarito Plateau. The lower cooling unit is formed by three to as many as six pyroclastic flow units; the middle and upper cooling units each consist of at least three pyroclastic flow units. The contact between the lower and middle cooling unit coincides with a pyroclastic flow unit contact. This horizon is a prominent stratigraphic marker within distal sections of the Tshirege Member. Major and trace element analyses of unaltered and altered samples of the Bandelier Tuff were determined by neutron activation and delayed neutron activation and delayed neutron activation techniques. Petrographic, granulometric and morphologic characteristics of the Bandelier Tuff were determined to provide background information on the suitability of the Tuff as a medium for radioactive waste disposal. The hydrologic characteristics of the Bandelier Tuff are controlled primarily by secondary features of the Tuff (cooling zones). These features vary with emplacement temperature and transport distance of the Tuff. Primary depositional features provide second order control on transport pathways in distal sections of the Tuff

  16. Felsic tuff from Rutland Island – A pyroclastic flow deposit in ...

    Indian Academy of Sciences (India)

    : • white massive tuff with ill-defined bedding contacts (facies-A) and. • dominantly green tuff exhibiting well-developed turbidite sequence with up-section change from a massive unit to plane laminated units to ripple drift lamination (facies-B).

  17. Environmental assessment: Davis Canyon site, Utah

    International Nuclear Information System (INIS)

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has fond that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization. 181 figs., 175 tabs

  18. Environmental assessment: Davis Canyon site, Utah

    Energy Technology Data Exchange (ETDEWEB)

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has fond that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization. 181 figs., 175 tabs.

  19. Scaling behavior of gas permeability measurements in volcanic tuffs

    International Nuclear Information System (INIS)

    Tidwell, V.C.

    1994-01-01

    One of the critical issues facing the Yucca Mountain site characterization and performance assessment programs is the manner in which property scaling is addressed. Property scaling becomes an issue whenever heterogeneous media properties are measured at one scale but applied at another. A research program has been established to challenge current understanding of property scaling with the aim of developing and testing models that describe scaling behavior in a quantitative manner. Scaling of constitutive rock properties is investigated through physical experimentation involving the collection of suites of gas-permeability data measured over a range of discrete scales. The approach is to systematically isolate those factors believed to influence property scaling and investigate their relative contributions to overall scaling behavior. Two blocks of tuff, each exhibiting differing heterogeneity structure, have recently been examined. Results of the investigation show very different scaling behavior, as exhibited by changes in the distribution functions and variograms, for the two tuff samples. Even for the relatively narrow range of measurement scales employed significant changes in the distribution functions, variograms, and summary statistics occurred. Because such data descriptors will likely play an important role in calculating effective media properties, these results demonstrate both the need to understand and accurately model scaling behavior

  20. Laboratory testing of cement grouting of fractures in welded tuff

    International Nuclear Information System (INIS)

    Sharpe, C.J.; Daemen, J.J.

    1991-03-01

    Fractures in the rock mass surrounding a repository and its shafts, access drifts, emplacement rooms and holes, and exploratory or in-situ testing holes, may provide preferential flowpaths for the flow of groundwater or air, potentially containing radionuclides. Such cracks may have to be sealed. The likelihood that extensive or at least local grouting will be required as part of repository sealing has been noted in numerous publications addressing high level waste repository closing. The objective of this work is to determine the effectiveness of fracture sealing (grouting) in welded tuff. Experimental work includes measurement of intact and fracture permeability under various normal stresses and injection pressures. Grout is injected into the fractures. The effectiveness of grouting is evaluated in terms of grout penetration and permeability reduction, compared prior to and after grouting. Analysis of the results include the effect of normal stress, injection pressure, fracture roughness, grout rheology, grout bonding, and the radial extent of grout penetration. Laboratory experiments have been performed on seventeen tuff cylinders with three types of fractures: (1) tension induced cracks, (2) natural fractures, and (3) sawcuts. Prior to grouting, the hydraulic conductivity of the intact rock and of the fractures is measured under a range of normal stresses. The surface topography of the fracture is mapped, and the results are used to determine aperture distributions across the fractures. 72 refs., 76 figs., 25 tabs

  1. Environmental effects on corrosion in the Tuff repository

    International Nuclear Information System (INIS)

    Beavers, J.A.; Thompson, N.G.

    1990-02-01

    Cortest Columbus is investigating the long-term performance of container materials used for high-level waste packages as part of the information needed by the Nuclear Regulatory Commission to assess the Department of Energy's application to construct a geologic repository for high-level radioactive waste. The scope of work consists of employing short-term techniques, to examine a wide range of possible failure modes. Long-term tests are being used to verify and further examine specific failure modes identified as important by the short-term studies. The original focus of the program was on the salt repository but the emphasis was shifted to the Tuff repository. This report summarizes the results of a literature survey performed under Task 1 of the program. The survey focuses on the influence of environmental variables on the corrosion behavior of candidate container materials for the Tuff repository. Environmental variables considered include: radiation, thermal and microbial effects. 80 refs., 44 figs., 44 tabs

  2. Mineralogic studies of tuff for high-level waste disposal

    International Nuclear Information System (INIS)

    Vaniman, D.; Bish, D.; Broxton, D.; Byers, F.; Carlos, B.; Levy, S.

    1986-01-01

    The volcanic rocks at Yucca Mountain, Nevada, consist predominantly of tuff that originated 12 to 14 million years ago as flows and airfalls of hot volcanic particulates. On cooling these units formed two major rock types: crystallized zones formed mostly of feldspar and silica minerals, and zones of glass. Alteration of glass to zeolite minerals occurred largely during structural tilting of Yucca Mountain in the ∼1-3 million years following the major eruptions. The compositions of zeolites formed from glasses strongly indicate open-system chemical exchange. Superimposed on this general alteration of glasses are areas of local high-temperature alteration. High-temperature alteration ended by 11 million years ago. Zeolites such as clinoptilolite persisted during high-temperature alteration at temperatures up to 100 degree C, suggesting that clinoptilolite at Yucca Mountain close to the thermally disturbed zone around a repository may also survive heating to temperatures at least this high. The mineralogic data from tuff at Yucca Mountain will ultimately be used by the Department of Energy Nevada Nuclear Waste storage Investigations for (1) defining the mineralogic component in estimating waste element travel times away from the repository and (2) determining the past history of alteration and the anticipated stability of minerals near the repository

  3. Wintertime Boundary Layer Structure in the Grand Canyon.

    Science.gov (United States)

    Whiteman, C. David; Zhong, Shiyuan; Bian, Xindi

    1999-08-01

    Wintertime temperature profiles in the Grand Canyon exhibit a neutral to isothermal stratification during both daytime and nighttime, with only rare instances of actual temperature inversions. The canyon warms during daytime and cools during nighttime more or less uniformly through the canyon's entire depth. This weak stability and temperature structure evolution differ from other Rocky Mountain valleys, which develop strong nocturnal inversions and exhibit convective and stable boundary layers that grow upward from the valley floor. Mechanisms that may be responsible for the different behavior of the Grand Canyon are discussed, including the possibility that the canyon atmosphere is frequently mixed to near-neutral stratification when cold air drains into the top of the canyon from the nearby snow-covered Kaibab Plateau. Another feature of canyon temperature profiles is the sharp inversions that often form near the canyon rims. These are generally produced when warm air is advected over the canyon in advance of passing synoptic-scale ridges.Wintertime winds in the main canyon are not classical diurnal along-valley wind systems. Rather, they are driven along the canyon axis by the horizontal synoptic-scale pressure gradient that is superimposed along the canyon's axis by passing synoptic-scale weather disturbances. They may thus bring winds into the canyon from either end at any time of day.The implications of the observed canyon boundary layer structure for air pollution dispersion are discussed.

  4. Mineralogy, petrology and whole-rock chemistry data compilation for selected samples of Yucca Mountain tuffs

    International Nuclear Information System (INIS)

    Connolly, J.R.

    1991-12-01

    Petrologic, bulk chemical, and mineralogic data are presented for 49 samples of tuffaceous rocks from core holes USW G-1 and UE-25a number-sign 1 at Yucca Mountain, Nevada. Included, in descending stratigraphic order, are 11 samples from the Topopah Spring Member of the Paintbrush Tuff, 12 samples from the Tuffaceous Beds of Calico Hills, 3 samples from the Prow Pass Member of the Crater Flat Tuff, 20 samples from the Bullfrog Member of the Crater Flat Tuff and 3 samples from the Tram Member of the Crater Flat Tuff. The suite of samples contains a wide variety of petrologic types, including zeolitized, glassy, and devitrified tuffs. Data vary considerably between groups of samples, and include thin section descriptions (some with modal analyses for which uncertainties are estimated), electron microprobe analyses of mineral phases and matrix, mineral identifications by X-ray diffraction, and major element analyses with uncertainty estimates

  5. Preliminary evaluation of alterant geophysical tomography in welded tuff

    International Nuclear Information System (INIS)

    Ramirez, A.L.; Daily, W.D.

    1985-01-01

    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-stained fractures coincides with the location of some image anomalies; other geophysical anomalies exist where tracer-stained 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

  6. Contemporary sediment-transport processes in submarine canyons.

    Science.gov (United States)

    Puig, Pere; Palanques, Albert; Martín, Jacobo

    2014-01-01

    Submarine canyons are morphological incisions into continental margins that act as major conduits of sediment from shallow- to deep-sea regions. However, the exact mechanisms involved in sediment transfer within submarine canyons are still a subject of investigation. Several studies have provided direct information about contemporary sedimentary processes in submarine canyons that suggests different modes of transport and various triggering mechanisms. Storm-induced turbidity currents and enhanced off-shelf advection, hyperpycnal flows and failures of recently deposited fluvial sediments, dense shelf-water cascading, canyon-flank failures, and trawling-induced resuspension largely dominate present-day sediment transfer through canyons. Additionally, internal waves periodically resuspend ephemeral deposits within canyons and contribute to dispersing particles or retaining and accumulating them in specific regions. These transport processes commonly deposit sediments in the upper- and middle-canyon reaches for decades or centuries before being completely or partially flushed farther down-canyon by large sediment failures.

  7. Red Rock Canyon National Conservation Area Transportation Feasibility Study

    Science.gov (United States)

    2012-07-31

    Red Rock Canyon National Conservation Area is a popular Bureau of Land Management natural area located near Las Vegas, Nevada. Red Rock Canyon experiences heavy congestion on its Scenic Drive and associated parking areas, due to high volumes of visit...

  8. Tectonic activity and the evolution of submarine canyons: The Cook Strait Canyon system, New Zealand

    Science.gov (United States)

    Micallef, Aaron; Mountjoy, Joshu; Barnes, Philip; Canals, Miquel; Lastras, Galderic

    2016-04-01

    Submarine canyons are Earth's most dramatic erosional features, comprising steep-walled valleys that originate in the continental shelf and slope. They play a key role in the evolution of continental margins by transferring sediments into deep water settings and are considered important biodiversity hotspots, pathways for nutrients and pollutants, and analogues of hydrocarbon reservoirs. Although comprising only one third of continental margins worldwide, active margins host more than half of global submarine canyons. We still lack of thorough understanding of the coupling between active tectonics and submarine canyon processes, which is necessary to improve the modelling of canyon evolution in active margins and derive tectonic information from canyon morphology. The objectives of this study are to: (i) understand how tectonic activity influences submarine canyon morphology, processes, and evolution in an active margin, and (2) formulate a generalised model of canyon development in response to tectonic forcing based on morphometric parameters. We fulfil these objectives by analysing high resolution geophysical data and imagery from Cook Strait Canyon system, offshore New Zealand. Using these data, we demonstrate that tectonic activity, in the form of major faults and structurally-generated tectonic ridges, leaves a clear topographic signature on submarine canyon location and morphology, in particular their dendritic and sinuous planform shapes, steep and linear longitudinal profiles, and cross-sectional asymmetry and width. We also report breaks/changes in canyon longitudinal slope gradient, relief and slope-area regression models at the intersection with faults. Tectonic activity gives rise to two types of knickpoints in the Cook Strait Canyon. The first type consists of low slope gradient, rounded and diffusive knickpoints forming as a result of short wavelength folds or fault break outs and being restored to an equilibrium profile by upstream erosion and

  9. 40Ar/39Ar age spectra from the KBS Tuff, Koobi Fora Formation

    International Nuclear Information System (INIS)

    McDougall, I.

    1981-01-01

    40 Ar/ 39 Ar age spectra on anorthoclase phenocrysts from three pumice clasts in the KBS Tuff yield nearly ideal flat patterns, providing good evidence that the samples have remained undisturbed since crystallization. The ages are concordant at 1.88 = 0.02 Myr, and confirm that the KBS Tuff, a key marker bed in the Koobi Fora Formation, northern Kenya, is now very well dated. These results resolve the conflict between earlier 40 Ar/ 39 Ar and conventional K-Ar dating measurements on the KBS Tuff. (author)

  10. 40Ar/39Ar age spectra from the KBS Tuff, Koobi Fora Formation.

    Science.gov (United States)

    McDougall, Ian

    1981-11-12

    40 Ar/ 39 Ar age spectra on anorthoclase phenocrysts from three pumice clasts in the KBS Tuff yield nearly ideal flat patterns, providing good evidence that the samples have remained undisturbed since crystallization. The ages are concordant at 1.88±0.02 Myr, and confirm that the KBS Tuff, a key marker bed in the Koobi Fora Formation, northern Kenya, is now very well dated. These results resolve the conflict between earlier 40 Ar/ 39 Ar and conventional K-Ar dating measurements on the KBS Tuff.

  11. 77 FR 22801 - Glen Canyon Dam Adaptive Management Work Group

    Science.gov (United States)

    2012-04-17

    ... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group...). SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG) makes recommendations to the Secretary..., the AMWG, a technical work group, a Grand Canyon Monitoring and Research Center, and independent...

  12. Crossing fitness canyons by a finite population

    Science.gov (United States)

    Saakian, David B.; Bratus, Alexander S.; Hu, Chin-Kun

    2017-06-01

    We consider the Wright-Fisher model of the finite population evolution on a fitness landscape defined in the sequence space by a path of nearly neutral mutations. We study a specific structure of the fitness landscape: One of the intermediate mutations on the mutation path results in either a large fitness value (climbing up a fitness hill) or a low fitness value (crossing a fitness canyon), the rest of the mutations besides the last one are neutral, and the last sequence has much higher fitness than any intermediate sequence. We derive analytical formulas for the first arrival time of the mutant with two point mutations. For the first arrival problem for the further mutants in the case of canyon crossing, we analytically deduce how the mean first arrival time scales with the population size and fitness difference. The location of the canyon on the path of sequences has a crucial role. If the canyon is at the beginning of the path, then it significantly prolongs the first arrival time; otherwise it just slightly changes it. Furthermore, the fitness hill at the beginning of the path strongly prolongs the arrival time period; however, the hill located near the end of the path shortens it. We optimize the first arrival time by applying a nonzero selection to the intermediate sequences. We extend our results and provide a scaling for the valley crossing time via the depth of the canyon and population size in the case of a fitness canyon at the first position. Our approach is useful for understanding some complex evolution systems, e.g., the evolution of cancer.

  13. Hydrogeology of Middle Canyon, Oquirrh Mountains, Tooele County, Utah

    Science.gov (United States)

    Gates, Joseph Spencer

    1963-01-01

    Geology and climate are the principal influences affecting the hydrology of Middle Canyon, Tooele County, Utah. Reconnaissance in the canyon indicated that the geologic influences on the hydrology may be localized; water may be leaking through fault and fracture zones or joints in sandstone and through solution openings in limestone of the Oquirrh formation of Pennsylvanian and Permian age. Surficial deposits of Quaternary age serve as the main storage material for ground water in the canyon and transmit water from the upper canyon to springs and drains at the canyon mouth. The upper canyon is a more important storage area than the lower canyon because the surficial deposits are thicker, and any zones of leakage in the underlying bedrock of the upper canyon probably would result in greater leakage than would similar outlets in the lower canyon.The total annual discharge from Middle Canyon, per unit of precipitation, decreased between 1910 and 1939. Similar decreases occurred in Parleys Canyon in the nearby Wasatch Range and in other drainage basins in Utah, and it is likely that most of the decrease in discharge from Middle Canyon and other canyons in Utah is due to a change in climate.Chemical analyses of water showed that the high content of sulfate and other constituents in the water from the Utah Metals tunnel, which drains into Middle Canyon, does not have a significant effect on water quality at the canyon mouth. This suggests that much of the tunnel water is lost from the channel by leakage, probably in the upper canyon, during the dry part of the year.Comparison of the 150 acre-feet of water per square mile of drainage area discharged by Middle Canyon in 1947 with the 623 and 543 acre-feet per square mile discharged in 1948 by City Creek and Mill Creek Canyons, two comparable drainage basins in the nearby Wasatch Range, also suggests that there is leakage in Middle Canyon.A hydrologic budget of the drainage basin results in an estimate that about 3,000 acre

  14. Let's Bet on Sediments! Hudson Canyon Cruise--Grades 9-12. Focus: Sediments of Hudson Canyon.

    Science.gov (United States)

    National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

    These activities are designed to teach about the sediments of Hudson Canyon. Students investigate and analyze the patterns of sedimentation in the Hudson Canyon, observe how heavier particles sink faster than finer particles, and learn that submarine landslides are avalanches of sediment in deep ocean canyons. The activity provides learning…

  15. Fission-track dating of pumice from the KBS Tuff, East Rudolf, Kenya

    Science.gov (United States)

    Hurford, A.J.; Gleadow, A.J.W.; Naeser, C.W.

    1976-01-01

    Fission-track dating of zircon separated from two pumice samples from the KBS Tuff in the Koobi Fora Formation, in Area 131, East Rudolf, Kenya, gives an age of 2.44??0.08 Myr for the eruption of the pumice. This result is compatible with the previously published K-Ar and 40Ar/ 39Ar age spectrum estimate of 2.61??0.26 Myr for the KBS Tuff in Area 105, but differs from the more recently published K-Ar date of 1.82??0.04 Myr for the KBS Tuff in Area 131. This study does not support the suggestion that pumice cobbles of different ages occur in the KBS Tuff. ?? 1976 Nature Publishing Group.

  16. TBM performance prediction in Yucca Mountain welded tuff from linear cutter tests

    International Nuclear Information System (INIS)

    Gertsch, R.; Ozdemir, L.; Gertsch, L.

    1992-01-01

    This paper discusses performance prediction which were developed for tunnel boring machines operating in welded tuff for the construction of the experimental study facility and the potential nuclear waste repository at Yucca Mountain. The predictions were based on test data obtained from an extensive series of linear cutting tests performed on samples of Topopah String welded tuff from the Yucca Mountain Project site. Using the cutter force, spacing, and penetration data from the experimental program, the thrust, torque, power, and rate of penetration were estimated for a 25 ft diameter tunnel boring machine (TBM) operating in welded tuff. The result show that the Topopah Spring welded tuff (TSw2) can be excavated at relatively high rates of advance with state-of-the-art TBMs. The result also show, however, that the TBM torque and power requirements will be higher than estimated based on rock physical properties and past tunneling experience in rock formations of similar strength

  17. Geohydrology of White Rock Canyon of the Rio Grande from Otowi to Frijoles Canyon

    International Nuclear Information System (INIS)

    Purtymun, W.D.; Peters, R.J.; Owens, J.W.

    1980-12-01

    Twenty-seven springs discharge from the Totavi Lentil and Tesuque Formation in White Rock Canyon. Water generally acquires its chemical characteristics from rock units that comprise the spring aquifer. Twenty-two of the springs are separated into three groups of similar aquifer-related chemical quality. The five remaining springs make up a fourth group with a chemical quality that differs due to localized conditions in the aquifer. Localized conditions may be related to recharge or discharge in or near basalt intrusion or through faults. Streams from Pajarito, Ancho, and Frijoles Canyons discharge into the Rio Grande in White Rock Canyon. The base flow in the streams is from springs. Sanitary effluent in Mortandad Canyon from the treatment plant at White Rock also reaches the Rio Grande

  18. Distribution of rubidium, strontium, and zirconium in tuff from two deep coreholes at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Spengler, R.W.; Peterman, Z.E.

    1991-01-01

    Variations in concentrations of trace elements Rb, Sr, and Zr within the sequence of high-silica tuff and dacitic lava beneath Yucca Mountain reflect both primary composition and secondary alteration. Rb and K concentrations have parallel trends. Rb concentrations are significantly lower within intervals containing zeolitic nonwelded to partially welded and bedded tuffs and are higher in thick moderately to densely welded zones. Sr concentrations increase with depth from about 30 parts per million (ppM) in the Topopah Spring Member of the Paintbrush Tuff to almost 300 ppM in the older tuffs. Zr concentrations are about 100 ppM in the Topopah Spring Member and also increase with depth to about 150 ppM in the Lithic Ridge Tuff and upper part of the older tuffs. Conspicuous local high concentrations of Sr in the lower part of the Tram Member, in the dacite lava, and in unit c of the older tuffs in USW G-1, and in the densely welded zone of the Bullfrog Member in USW GU-3/G-3 closely correlate with high concentrations of less-mobile Zr and may reflect either primary composition or elemental redistribution resulting largely from smectitic alteration. Initial 87 Sr/ 86 Sr values from composite samples increase upward in units above the Bullfrog Member of the Crater Flat Tuff. The progressive tenfold increase in Sr with depth coupled with the similarity of initial 87 Sr/ 86 Sr values within the Bullfrog Member and older units to those of Paleozoic marine carbonates are consistent with a massive influx or Sr from water derived from a Paleozoic carbonate aquifer. 23 refs., 4 figs., 1 tab

  19. Pollutant Dilution and Diffusion in Urban Street Canyon Neighboring Streets

    Science.gov (United States)

    Sun, Z.; Fu, Zh. M.

    2011-09-01

    In the present study we investigated the airflow patterns and air quality of a series of typical street canyon combinations, developed a mass balance model to determine the local pollutant dilution rate, and discuss the impact of upstream canyon on the air quality of downstream canyon. The results indicated that the geometrical size of upstream and downstream buildings have significant impacts on the ambient airflow patterns. The pollution distribution within the canyons varies with different building combinations and flow patterns. Within the upstream canyon, pollution always accumulates to the low building side for non-symmetrical canyon, and for symmetrical canyon high level of pollution occurs at the leeward side. The height of the middle and downstream buildings can evidently change the pollutant dispersion direction during the transport process. Within the polluted canyon, the pollutant dilution rate (PDR) also varies with different street canyon combinations. The highest PDR is observed when the upstream buildings are both low buildings no matter the height of downstream building. However, the two cases are likely to contribution pollution to the downstream canyon. The H-L-H combination is mostly against local pollution remove, while the L-H-L case is considered the best optimistic building combination with both the ability of diluting local pollution and not remarkably decreasing air quality of downstream canyon. The current work is expected instructive for city designers to optimize traffic patterns under typical existing geometry or in the development of urban geometry modification for air quality control.

  20. Chemistry and mineralogy of some Plio-Pleistocene tuffs from the Shungura Formation, southwest Ethiopia

    Science.gov (United States)

    Martz, A. M.; Brown, F. H.

    1981-09-01

    The Shungura Formation of southwestern Ethiopia has yielded many tens of thousands of vertebrate fossils including hominids and microvertebrates, and in addition has also yielded fossil wood, pollen, and invertebrates. Widespread tuffs have made subdivision and detailed mapping of the formation possible, have provided material for potassium-argon dating, and have allowed direct lithostratigraphic correlation with the Koobi Fora Formation in northern Kenya. The basis for correlation between the two formations is the distinctive chemistry of the tuffs, but systematic chemical variation within some tuffs invalidates some statistical correlation techniques. Here chemical analysis of glass separates and minerals from tuffs of the Shungura and Usno Formations are presented which may allow further ties to be established when data become available on other tuffs of the Koobi Fora Formation. The tuffs consist primarily of glass, but also contain phenocrysts of anorthoclase, hedenbergitic pyroxene, sodic amphibole, ilmenite, titanomagnetite, chevkinite, quartz, zircon, and rarely orthopyroxene and plagioclase. The glasses show evidence of alkali loss during hydration, and are not now peralkaline, although it is likely that they were initially. The source volcanoes were most likely situated within the Ethiopian rift valley, or on its margins.

  1. METHODS FOR PORE WATER EXTRACTION FROM UNSATURATED ZONE TUFF, YUCCA MOUNTAIN, NEVADA

    International Nuclear Information System (INIS)

    K.M. SCOFIELD

    2006-01-01

    Assessing the performance of the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, requires an understanding of the chemistry of the water that moves through the host rock. The uniaxial compression method used to extract pore water from samples of tuffaceous borehole core was successful only for nonwelded tuff. An ultracentrifugation method was adopted to extract pore water from samples of the densely welded tuff of the proposed repository horizon. Tests were performed using both methods to determine the efficiency of pore water extraction and the potential effects on pore water chemistry. Test results indicate that uniaxial compression is most efficient for extracting pore water from nonwelded tuff, while ultracentrifugation is more successful in extracting pore water from densely welded tuff. Pore water splits taken from a single nonwelded tuff core during uniaxial compression tests have shown changes in pore water chemistry with increasing pressure for calcium, chloride, sulfate, and nitrate, while the chemistry of pore water splits from welded and nonwelded tuffs using ultracentrifugation indicates that there is no significant fractionation of solutes

  2. Measuring geomechanical properties of Topopah Spring Tuff at the 1-meter scale

    International Nuclear Information System (INIS)

    Blair, S.C.; Berge, P.A.

    1994-11-01

    The Yucca Mountain Site Characterization Project is studying physical and chemical properties of Topopah Spring tuff and coupled thermal, mechanical, hydrological, and geochemical processes expected in the near-field environment of the potential waste repository at Yucca Mountain, Nevada. Investigating the suitability of Topopah Spring tuff as a host rock for radioactive waste disposal includes measuring mechanical properties. Since heterogeneities vary with scale, from vugs and cracks at the hand-sample scale to fractures and vertical variations in degree of welding at the outcrop scale, mechanical properties of the tuff depend on scale. The Lawrence Livermore National Laboratory has planned a Large Block Test (LBT) to investigate rock mass properties and coupled processes at elevated temperatures in Topopah Spring tuff at the scale of a few meters. This paper describes planned laboratory experiments in support of the LBT, to measure elastic properties and mechanical behavior of Topopah Spring tuff at the scale of a few cm to 1 m. The laboratory experiments will include measurement of stress-strain behavior, acoustic emissions during heating, and elastic wave velocities in small blocks of tuff

  3. Recreational impacts on Colorado River beaches in Glen Canyon, Arizona

    Science.gov (United States)

    Carothers, Steven W.; Johnson, Robert A.; Dolan, Robert

    1984-07-01

    Recreational impact was measured on eight beaches in Glen Canyon National Recreation Area and 15 beaches in Grand Canyon National Park using permanently located transects and plots. Recreational impact indices included densities of human trash and charcoal and a measure of sand discoloration due to charcoal. Significant increases in the indices occurred on several Glen Canyon beaches over a seven-month period. Sand discoloration became significantly higher over all Glen Canyon beaches during the same time period. All indices were significantly higher in Glen Canyon than on similar Grand Canyon beaches. These differences are probably due to differences in: (a) level of impacts tolerated by the respective management regimes and, (b) in the number of user days among the two National Park Service administrative units. Management alternatives are presented for reversing the present trends of recreational impact on Glen Canyon beaches.

  4. Submarine canyons off the Coromandel coast

    Digital Repository Service at National Institute of Oceanography (India)

    Varadachari, V.V.R.; Nair, R.R.; Murty, P.S.N.

    During the 26th Cruise of I.N.S. `KISTNA', a bathymetric survey was carried out in some detail off the Pondicherry coast. This survey has revealed the existence of three sets of distinctly separate canyons between Cuddalore and Palar River...

  5. Assessment of changes at Glen Canyon Dam

    International Nuclear Information System (INIS)

    Cherry, D.; McCoy, J.; Crandall, S.

    1991-01-01

    This paper describes the complexity associated with the assessment of financial impacts of proposed and actual short-term restrictions at Glen Canyon Dam. The reasons for these restrictions are discussed as well as the methods used to measure their financial impact to Western Area Power Administration

  6. ACUMEN 2012: Atlantic Canyons Undersea Mapping Expeditions

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Between February and August 2012, a team of NOAA and external partners will conduct a mapping ‘blitz’ focused on deepwater canyons off the northeastern...

  7. Turbulent ventilation of a street canyon

    DEFF Research Database (Denmark)

    Nielsen, Morten

    2000-01-01

    A selection of turbulence data corresponding to 185 days of field measurements has een analysed. The non-ideal building geometry influenced the circulation patterns in the street canyon and the largest average vertical velocities were observed in the wake of an unbroken line of buildings. The sta...

  8. Anatomy of La Jolla submarine canyon system; offshore southern California

    Science.gov (United States)

    Paull, C.K.; Caress, D.W.; Lundsten, E.; Gwiazda, R.; Anderson, K.; McGann, M.; Conrad, J.; Edwards, B.; Sumner, E.J.

    2013-01-01

    An autonomous underwater vehicle (AUV) carrying a multibeam sonar and a chirp profiler was used to map sections of the seafloor within the La Jolla Canyon, offshore southern California, at sub-meter scales. Close-up observations and sampling were conducted during remotely operated vehicle (ROV) dives. Minisparker seismic-reflection profiles from a surface ship help to define the overall geometry of the La Jolla Canyon especially with respect to the pre-canyon host sediments. The floor of the axial channel is covered with unconsolidated sand similar to the sand on the shelf near the canyon head, lacks outcrops of the pre-canyon host strata, has an almost constant slope of 1.0° and is covered with trains of crescent shaped bedforms. The presence of modern plant material entombed within these sands confirms that the axial channel is presently active. The sand on the canyon floor liquefied during vibracore collection and flowed downslope, illustrating that the sediment filling the channel can easily fail even on this gentle slope. Data from the canyon walls help constrain the age of the canyon and extent of incision. Horizontal beds of moderately cohesive fine-grained sediments exposed on the steep canyon walls are consistently less than 1.232 million years old. The lateral continuity of seismic reflectors in minisparker profiles indicate that pre-canyon host strata extend uninterrupted from outside the canyon underneath some terraces within the canyon. Evidence of abandoned channels and point bar-like deposits are noticeably absent on the inside bend of channel meanders and in the subsurface of the terraces. While vibracores from the surface of terraces contain thin (< 10 cm) turbidites, they are inferred to be part of a veneer of recent sediment covering pre-canyon host sediments that underpin the terraces. The combined use of state of the art seafloor mapping and exploration tools provides a uniquely detailed view of the morphology within an active submarine canyon.

  9. Immersion studies on candidate container alloys for the Tuff Repository

    International Nuclear Information System (INIS)

    Beavers, J.A.; Durr, C.L.

    1991-05-01

    Cortest Columbus Technologies (CC Technologies) is investigating the long-term performance of container materials used for high-level radioactive waste packages. This information is being developed for the Nuclear Regulatory Commission to aid in their assessment of the Department of Energy's application to construct a geologic repository for disposal of high-level radioactive waste. This report summarizes the results of exposure studies performed on two copper-base and two Fe-Cr-Ni alloys in simulated Tuff Repository conditions. Testing was performed at 90 degrees C in three environments; simulated J-13 well water, and two environments that simulated the chemical effects resulting from boiling and irradiation of the groundwater. Creviced specimens and U-bends were exposed to liquid, to vapor above the condensed phase, and to alternate immersion. A rod specimen was used to monitor corrosion at the vapor-liquid interface. The specimens were evaluated by electrochemical, gravimetric, and metallographic techniques following approximately 2000 hours of exposure. Results of the exposure tests indicated that all four alloys exhibited acceptable general corrosion rates in simulated J-13 well water. These rates decreased with time. Incipient pitting was observed under deposits on Alloy 825 and pitting was observed on both Alloy CDA 102 and Alloy CDA 715 in the simulated J-13 well water. No SCC was observed in U-bend specimens of any of the alloys in simulated J-13 well water. 33 refs., 48 figs., 23 tabs

  10. Monitoring the vadose zone in fractured tuff, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Montazer, P.; Weeks, E.P.; Thamir, F.; Yard, S.N.; Hofrichter, P.B.

    1985-01-01

    Unsaturated tuff beneath Yucca Mountain, Nevada, is being evaluated by the US Department of Energy as a host rock for a potential repository for high-level radioactive waste. As part of the Nevada Nuclear Waste Storage Investigations Project of the US Department of Energy, the US Geological Survey has been conducting hydrologic, geologic, and geophysical investigations at Yucca Mountain and the surrounding region to provide data evaluation of the potential suitability of the site. Hydrologic investigations of the unsaturated zone at this site were started in 1982. A 17.5-inch- (44.5-centimeter-) diameter borehole (USW UZ-1) was drilled by the reverse-air vacuum-drilling technique to a depth of 1269 feet (387 meters). This borehole was instrumented at 33 depth levels. At 15 of the levels, 3 well screens were embedded in coarse-sand columns. The sand columns were isolated from each other by thin layers of bentonite, columns of silica flour, and isolation plugs consisting of expansive cement. Thermocouple psychrometers and pressure transducers were installed within the screens and connected to the data-acquisition system at the land surface through thermocouple and logging cables. Two of the screens at each level were equipped with access tubes to allow collection of pore-gas samples. In addition to these instruments, 18 heat-dissipation probes were installed within the columns of silica flour, some of which also had thermocouple psychrometers. 20 refs., 13 figs., 2 tabs

  11. Predicting spent fuel oxidation states in a tuff repository

    International Nuclear Information System (INIS)

    Einziger, R.E.; Woodley, R.E.

    1987-01-01

    Nevada Nuclear Waste Storage Investigations Project (NNWSI) is studying the suitability of the tuffaceous rocks at Yucca Mountain as a waste repository for spent fuel disposal. The oxidation state of the LWR spent fuel in the moist air environment of a tuff repository could be a significant factor in determining its leaching and dissolution characteristics. Predictions as to which oxidation states would be present are important in analyzing such a repository and thus the present study was undertaken. A set of TGA (thermogravimetric analysis) tests were conducted on well-controlled samples of irradiated PWR fuel with time and temperature as the only variables. The tests were conducted between 140 and 225 0 C for a duration up to 2200 hours. The weight gain curves were analyzed in terms of diffusion through a layer of U 3 O 7 , diffusion into the grains to form a solid solution, a simplified empirical representation of a combination of grain boundary diffusion and bulk grain oxidation. Reaction rate constants were determined in each case, but analysis of these data could not establish a definitive mechanism. 21 refs., 10 figs., 3 tabs

  12. Preliminary drift design analyses for nuclear waste repository in tuff

    International Nuclear Information System (INIS)

    Hardy, M.P.; Brechtel, C.E.; Goodrich, R.R.; Bauer, S.J.

    1990-01-01

    The Yucca Mountain Project (YMP) is examining the feasibility of siting a repository for high-level nuclear waste at Yucca Mountain, on and adjacent to the Nevada Test Site (NTS). The proposed repository will be excavated in the Topopah Spring Member, which is a moderately fractured, unsaturated, welded tuff. Excavation stability will be required during construction, waste emplacement, retrieval (if required), and closure to ensure worker safety. The subsurface excavations will be subject to stress changes resulting from thermal expansion of the rock mass and seismic events associated with regional tectonic activity and underground nuclear explosions (UNEs). Analyses of drift stability are required to assess the acceptable waste emplacement density, to design the drift shapes and ground support systems, and to establish schedules and cost of construction. This paper outlines the proposed methodology to assess drift stability and then focuses on an example of its application to the YMP repository drifts based on preliminary site data. Because site characterization activities have not begun, the database currently lacks the extensive site-specific field and laboratory data needed to form conclusions as to the final ground support requirements. This drift design methodology will be applied and refined as more site-specific data are generated and as analytical techniques and methodologies are verified during the site characterization process

  13. Geophysical tomography for imaging water movement in welded tuff

    International Nuclear Information System (INIS)

    Daily, W.; Ramirez, A.

    1986-01-01

    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

  14. The behavior of biogenic silica-rich rocks and volcanic tuffs as pozzolanic additives in cement

    Science.gov (United States)

    Fragoulis, Dimitris; Stamatakis, Michael; Anastasatou, Marianthi

    2015-04-01

    Cements currently produced, include a variety of pozzolanic materials, aiming for lower clinker addition and utilization of vast deposits of certain raw materials and/or mining wastes and byproducts. The major naturally occurring pozzolanic materials include glassy tuffs, zeolitic tuffs, diatomites and volcanic lavas rich in glassy phase, such as perlites. Therefore, based on the available raw materials in different locations, the cement composition might vary according to the accessibility of efficient pozzolanic materials. In the present investigation, the behavior of pozzolanic cements produced with representative samples of the aforementioned materials was studied, following the characterization of the implemented pozzolanas with respect to their chemical and mineralogical characteristics. Laboratory cements were produced by co-grinding 75% clinker, 5% gypsum and 20% pozzolana, for the same period of time (45 min). Regarding pozzolanic materials, four different types of pozzolanas were utilized namely, diatomite, perlite, zeolite tuff and glassy tuff. More specifically, two diatomite samples originated from Australia and Greece, with high and low reactive silica content respectively, two perlite samples originated from Turkey and from Milos Island, Greece, with different reactive silica contents, a zeolite tuff sample originated from Turkey and a glassy tuff sample originated from Milos Island, Greece. The above pozzolana samples, which were ground in the laboratory ball mill for cement production performed differently during grinding and that was reflected upon the specific surface area (cm2/gr) values. The perlites and the glassy tuff were the hardest to grind, whereas, the zeolite tuff and the Australian diatomite were the easiest ones. However, the exceedingly high specific surface area of the Australian diatomite renders cement difficult to transport and tricky to use for concrete manufacturing, due to the high water demand of the cement mixture. Regarding

  15. Decreasing Slip Rates From 12.8 Ma to Present on the Solitario Canyon Fault at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    D. Buesch

    2006-01-01

    The Solitario Canyon fault, which bounds the west side of Yucca Mountain, Nevada, is the closest fault with Quaternary offset adjacent to the proposed spent nuclear fuel and high-level radioactive waste repository. Dip-slip offset between 12.8 and 10.7 Ma is determined from lithostratigraphic displacement in boreholes USW H-3 and USW WT-7, drilled in the footwall and hanging wall, respectively. The base of the 12.8-Ma Topopah Spring Tuff is interpreted to have 463.3 m of separation across the fault, an average dip slip rate of 0.036 mm/yr. Previous researchers identified a geothermal system active from 11.5 to 10.0 Ma with peak activity at 10.7 Ma that resulted in pervasive alteration of vitric rock to zeolitic minerals where the rocks were in the ground-water saturated zone. The contact between vitric (V) and pervasively zeolitic (Z) rocks cuts across the lithostratigraphic section and offset of this V-Z boundary can be used to measure slip rates between 12.8 and 10.7 Ma. In H-3, the V-Z boundary is 138.4 m below the base of the vitric, densely welded subzone of the Topopah Spring Tuff (Tptpv3). In WT-7, although the V-Z boundary is identified at the base of the Tptpv3, borehole video, cuttings, and geophysical log data indicate the Tptpv3 has well-developed zeolitic alteration along fractures, and this implies 19.5 m of the total thickness of Tptpv3 (and probably additional overlying crystallized rocks) also were in the saturated zone by 10.7 Ma. The V-Z relations across the Solitario Canyon fault in H-3 and WT-7 indicate a minimum of 157.9 m of separation before 10.7 Ma, which is 34.1 percent of the total slip of the Topopah Spring Tuff, and a minimum dip slip rate of 0.075 mm/yr from 12.8 to 10.7 Ma. These data are consistent with the broader structural history of the area near Yucca Mountain. Previous workers used angular unconformities, tilting of structural blocks, and paleomagnetic data to constrain the main period of extensional faulting between 12.7 and 8

  16. Anatomy of La Jolla submarine canyon system; offshore southern California

    Science.gov (United States)

    Paull, C.K.; Caress, D.W.; Lundsten, E.; Gwiazda, R.; Anderson, K.; McGann, M.; Conrad, J.; Edwards, B.; Sumner, E.J.

    2013-01-01

    An autonomous underwater vehicle (AUV) carrying a multibeam sonar and a chirp profiler was used to map sections of the seafloor within the La Jolla Canyon, offshore southern California, at sub-meter scales. Close-up observations and sampling were conducted during remotely operated vehicle (ROV) dives. Minisparker seismic-reflection profiles from a surface ship help to define the overall geometry of the La Jolla Canyon especially with respect to the pre-canyon host sediments. The floor of the axial channel is covered with unconsolidated sand similar to the sand on the shelf near the canyon head, lacks outcrops of the pre-canyon host strata, has an almost constant slope of 1.0° and is covered with trains of crescent shaped bedforms. The presence of modern plant material entombed within these sands confirms that the axial channel is presently active. The sand on the canyon floor liquefied during vibracore collection and flowed downslope, illustrating that the sediment filling the channel can easily fail even on this gentle slope. Data from the canyon walls help constrain the age of the canyon and extent of incision. Horizontal beds of moderately cohesive fine-grained sediments exposed on the steep canyon walls are consistently less than 1.232 million years old. The lateral continuity of seismic reflectors in minisparker profiles indicate that pre-canyon host strata extend uninterrupted from outside the canyon underneath some terraces within the canyon. Evidence of abandoned channels and point bar-like deposits are noticeably absent on the inside bend of channel meanders and in the subsurface of the terraces. While vibracores from the surface of terraces contain thin (art seafloor mapping and exploration tools provides a uniquely detailed view of the morphology within an active submarine canyon.

  17. Geologic character of tuffs in the unsaturated zone at Yucca Mountain, southern Nevada

    International Nuclear Information System (INIS)

    Scott, R.B.; Spengler, R.W.; Diehl, S.; Lappin, A.R.; Chornack, M.P.

    1982-01-01

    At Yucca Mountain, a potential site for a high-level nuclear waste repository on the Nevada Test Site in southern Nevada, evaluation of the geologic setting and rock physical properties, along with previous regional hydrologic studies, has provided background that can be used for construction of a preliminary conceptual hydrologic model of the unsaturated zone. The 500-m-thick unsaturated portion of Yucca Mountain consists of alternating layers of two contrasting types of tuff. One type consists of highly fractured, densely welded, relatively nonporous but highly transmissive ash-flow tuffs. The other type consists of relatively unfractured, nonwelded, highly porous but relatively nontransmissive, argillic and zeolitic bedded tuffs and ash-flow tuffs. The contrast between these two sets of distinctive physical properties results in a stratified sequence best described as ''physical-property stratigraphy'' as opposed to traditional petrologic stratigraphy of volcanic rocks. The vast majority of recharge through the unsaturated zone is assumed to be vertical; the dominant migration may occur in fractures of densely welded tuffs and in the matrix of nonwelded tuff, but the mode of fluid flow in these unsaturated systems is undetermined. Limited lateral flow of recharge may occur at horizons where local perched water tables may exist above relatively nontransmissive zeolitized nonwelded tuffs. The pervasive north-northwest-striking fractures may control the direction of lateral flow of recharge, if any, in the unsaturated zone, and certainly that direction coincides closely with the observed southeasterly flow direction in the saturated zone under Yucca Mountain. Empirical evaluation of this conceptual hydrologic model has begun. 41 refs., 18 figs., 2 tabs

  18. Feldspar dissolution rates in the Topopah Spring Tuff, Yucca Mountain, Nevada

    Science.gov (United States)

    Bryan, C.R.; Helean, K.B.; Marshall, B.D.; Brady, P.V.

    2009-01-01

    Two different field-based methods are used here to calculate feldspar dissolution rates in the Topopah Spring Tuff, the host rock for the proposed nuclear waste repository at Yucca Mountain, Nevada. The center of the tuff is a high silica rhyolite, consisting largely of alkali feldspar (???60 wt%) and quartz polymorphs (???35 wt%) that formed by devitrification of rhyolitic glass as the tuff cooled. First, the abundance of secondary aluminosilicates is used to estimate the cumulative amount of feldspar dissolution over the history of the tuff, and an ambient dissolution rate is calculated by using the estimated thermal history. Second, the feldspar dissolution rate is calculated by using measured Sr isotope compositions for the pore water and rock. Pore waters display systematic changes in Sr isotopic composition with depth that are caused by feldspar dissolution. The range in dissolution rates determined from secondary mineral abundances varies from 10-16 to 10-17 mol s-1 kg tuff-1 with the largest uncertainty being the effect of the early thermal history of the tuff. Dissolution rates based on pore water Sr isotopic data were calculated by treating percolation flux parametrically, and vary from 10-15 to 10-16 mol s-1 kg tuff-1 for percolation fluxes of 15 mm a-1 and 1 mm a-1, respectively. Reconciling the rates from the two methods requires that percolation fluxes at the sampled locations be a few mm a-1 or less. The calculated feldspar dissolution rates are low relative to other measured field-based feldspar dissolution rates, possibly due to the age (12.8 Ma) of the unsaturated system at Yucca Mountain; because oxidizing and organic-poor conditions limit biological activity; and/or because elevated silica concentrations in the pore waters (???50 mg L-1) may inhibit feldspar dissolution. ?? 2009 Elsevier Ltd. All rights reserved.

  19. Geologic character of tuffs in the unsaturated zone at Yucca Mountain, southern Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Scott, R.B.; Spengler, R.W.; Diehl, S.; Lappin, A.R.; Chornack, M.P.

    1982-12-31

    At Yucca Mountain, a potential site for a high-level nuclear waste repository on the Nevada Test Site in southern Nevada, evaluation of the geologic setting and rock physical properties, along with previous regional hydrologic studies, has provided background that can be used for construction of a preliminary conceptual hydrologic model of the unsaturated zone. The 500-m-thick unsaturated portion of Yucca Mountain consists of alternating layers of two contrasting types of tuff. One type consists of highly fractured, densely welded, relatively nonporous but highly transmissive ash-flow tuffs. The other type consists of relatively unfractured, nonwelded, highly porous but relatively nontransmissive, argillic and zeolitic bedded tuffs and ash-flow tuffs. The contrast between these two sets of distinctive physical properties results in a stratified sequence best described as "physical-property stratigraphy" as opposed to traditional petrologic stratigraphy of volcanic rocks. The vast majority of recharge through the unsaturated zone is assumed to be vertical; the dominant migration may occur in fractures of densely welded tuffs and in the matrix of nonwelded tuff, but the mode of fluid flow in these unsaturated systems is undetermined. Limited lateral flow of recharge may occur at horizons where local perched water tables may exist above relatively nontransmissive zeolitized nonwelded tuffs. The pervasive north-northwest-striking fractures may control the direction of lateral flow of recharge, if any, in the unsaturated zone, and certainly that direction coincides closely with the observed southeasterly flow direction in the saturated zone under Yucca Mountain. Empirical evaluation of this conceptual hydrologic model has begun. 41 refs., 18 figs., 2 tabs.

  20. 3D View of Grand Canyon, Arizona

    Science.gov (United States)

    2000-01-01

    The Grand Canyon is one of North America's most spectacular geologic features. Carved primarily by the Colorado River over the past six million years, the canyon sports vertical drops of 5,000 feet and spans a 445-kilometer-long stretch of Arizona desert. The strata along the steep walls of the canyon form a record of geologic time from the Paleozoic Era (250 million years ago) to the Precambrian (1.7 billion years ago).The above view was acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument aboard the Terra spacecraft. Visible and near infrared data were combined to form an image that simulates the natural colors of water and vegetation. Rock colors, however, are not accurate. The image data were combined with elevation data to produce this perspective view, with no vertical exaggeration, looking from above the South Rim up Bright Angel Canyon towards the North Rim. The light lines on the plateau at lower right are the roads around the Canyon View Information Plaza. The Bright Angel Trail, which reaches the Colorado in 11.3 kilometers, can be seen dropping into the canyon over Plateau Point at bottom center. The blue and black areas on the North Rim indicate a forest fire that was smoldering as the data were acquired on May 12, 2000.Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as

  1. A strategy to seal exploratory boreholes in unsaturated tuff

    International Nuclear Information System (INIS)

    Fernandez, J.A.; Case, J.B.; Givens, C.A.; Carney, B.C.

    1994-04-01

    This report presents a strategy for sealing exploratory boreholes associated with the Yucca Mountain Site Characterization Project. Over 500 existing and proposed boreholes have been considered in the development of this strategy, ranging from shallow (penetrating into alluvium only) to deep (penetrating into the groundwater table). Among the comprehensive list of recommendations are the following: Those boreholes within the potential repository boundary and penetrating through the potential repository horizon are the most significant boreholes from a performance standpoint and should be sealed. Shallow boreholes are comparatively insignificant and require only nominal sealing. The primary areas in which to place seals are away from high-temperature zones at a distance from the potential repository horizon in the Paintbrush nonwelded tuff and the upper portion of the Topopah Spring Member and in the tuffaceous beds of the Calico Hills Unit. Seals should be placed prior to waste emplacement. Performance goals for borehole seals both above and below the potential repository are proposed. Detailed construction information on the boreholes that could be used for future design specifications is provided along with a description of the environmental setting, i.e., the geology, hydrology, and the in situ and thermal stress states. A borehole classification scheme based on the condition of the borehole wall in different tuffaceous units is also proposed. In addition, calculations are presented to assess the significance of the boreholes acting as preferential pathways for the release of radionuclides. Design calculations are presented to answer the concerns of when, where, and how to seal. As part of the strategy development, available technologies to seal exploratory boreholes (including casing removal, borehole wall reconditioning, and seal emplacement) are reviewed

  2. Estimates of the width of the wetting zone along a fracture subjected to an episodic infiltration event in variably saturated, densely welded tuff

    International Nuclear Information System (INIS)

    Buscheck, T.A.; Nitao, J.J.

    1988-01-01

    A central issue to be addressed within the Nevada Nuclear Waste Storage Investigations (NNWSI) is the role which fractures will play as the variably saturated, fractured rock mass surrounding the waste package responds to heating, cooling, and episodic infiltration events. Understanding the role of fractures during such events will, in part, depend on our ability to make geophysical measurements of perturbations in the moisture distribution in the vicinity of fractures. In this study we first examine the details of the perturbation in the moisture distribution in and around a fracture subjected to an episodic infiltration event, and then integrate that behavior over the scale at which moisture measurements are likely to be made during the Engineered Barrier Design Test of the NNWSI project. To model this system we use the TOUGH hydrothermal code and fracture and matrix properties considered relevant to the welded ash flow tuff found in the Topopah Spring member at Yucca Mountain as well as in the Grouse Canyon member within G-Tunnel at the Nevada Test Site. Our calculations provide insight into the anticipated spatial and temporal resolution obtainable through the use of the geophysical techniques being considered. These calculations should prove useful both in planning the implementation of these methods as well as in the interpretation of their results. 41 refs., 28 figs

  3. Reactivity of a tuff-bearing concrete: CL-40 CON-14

    International Nuclear Information System (INIS)

    Scheetz, B.E.; Roy, D.M.

    1989-04-01

    Samples of a tuff-bearing concrete have been altered in J-13 groundwater and in the vapor phase over deionized water at 200/degree/C. Crushed and intact discs of the concrete have been studied. The glassy tuff component of the tuff was more extensively reacted than the welded devitrified tuff. The original concrete was formulated to be expansive on curing through the formation of the calcium alumino-sulfate hydrate phase, ettringite. An x-ray diffraction examination of the altered crushed samples shows that the ettringite is no longer present. The original, poorly crystalline calcium-silicate-hydrate has recrystallized to tobermorite. In the rocking autoclave experiments with crushed material, which are the experiments expected to have the fastest reaction rates, the tobermorite has been replaced by a mineral of the gyrolite-truscottite group at the longer reaction times. The disc experiments in J-13 groundwater are characterized by prominent dissolution of the tuff aggregate. Alteration in the vapor phase experiments is primarily in the form of overgrowths on the discs. 10 refs., 27 figs., 12 tabs

  4. Actinide transport in Topopah Spring Tuff: Pore size, particle size, and diffusion

    International Nuclear Information System (INIS)

    Buchholtz ten Brink, M.; Phinney, D.L.; Smith, D.K.

    1991-04-01

    Diffusive transport rates for aqueous species in a porous medium are a function of sorption, molecular diffusion, and sample tortuosity. With heterogeneous natural samples, an understanding of the effect of multiple transport paths and sorption mechanisms is particularly important since a small amount of radioisotope traveling via a faster-than-anticipated transport path may invalidate the predictions of transport codes which assume average behavior. Static-diffusion experiments using aqueous 238 U tracer in tuff indicated that U transport was faster in regions of greater porosity and that apparent diffusion coefficients depended on the scale (m or μm) over which concentration gradients were measured in Topopah Spring Tuff. If a significant fraction of actinides in high-level waste are released to the environment in forms that do not sorb to the matrix, they may be similarly transported along fast paths in porous regions of the tuff. To test this, aqueous diffusion rates in tuff were measured for 238 U and 239 Pu leached from doped glass. Measured transport rates and patterns were consistent in both systems with a dual-porosity transported moeld. In addition, filtration or channelling of actinides associated with colloidal particles may significantly affect the radionuclide transport rate in Topopah Spring tuff. 9 refs., 7 figs

  5. Thermal conductivity of silicic tuffs: predictive formalism and comparison with preliminary experimental results

    International Nuclear Information System (INIS)

    Lappin, A. R.

    1980-07-01

    Performance of both near- and far-field thermomechanical calculations to assess the feasibility of waste disposal in silicic tuffs requires a formalism for predicting thermal conductivity of a broad range of tuffs. This report summarizes the available thermal conductivity data for silicate phases that occur in tuffs and describes several grain-density and conductivity trends which may be expected to result from post-emplacement alteration. A bounding curve is drawn that predicts the minimum theoretical matrix (zero-porosity) conductivity for most tuffs as a function of grain density. Comparison of experimental results with this curve shows that experimental conductivities are consistently lower at any given grain density. Use of the lowered bounding curve and an effective gas conductivity of 0.12 W/m 0 C allows conservative prediction of conductivity for a broad range of tuff types. For the samples measured here, use of the predictive curve allows estimation of conductivity to within 15% or better, with one exception. Application and possible improvement of the formalism are also discussed

  6. Preliminary survey of tuff distribution in Esmeralda, Nye, and Lincoln Counties, Nevada

    International Nuclear Information System (INIS)

    Smith, G.V.; Pink, T.S.; Lawrence, J.R.; Woodward, L.A.; Keil, K.; Lappin, A.R.

    1981-02-01

    This report inventories the surface distribution of silicic tuffs in Nye, Esmeralda, and Lincoln Counties, NV, based on a review of available literature. The inventory was taken to provide a data base in evaluating tuff sites for the disposal of high-level nuclear waste. Silicic ash-flow tuffs that are about 11 to 34 million years (my) old are widespread in these counties. These rocks are locally deformed by right-lateral movement along Walker Lane and the Las Vegas Shear Zone, and left-lateral movement along a zone from near the Nevada Test Site (NTS) to the Utah border, and are commonly offset by steeply dipping normal faults. The normal faults that bound horsts, grabens, and tilted-fault blocks of the Basin-and-Range Province began to form 30 my ago; some are still active. Tuff distribution is discussed on a regional basis. Tuff thicknesses and alterations, structural complexity, and proximity to recent faulting, recent volcanism, and mineral resources are discussed for each area. Although the literature on which it is based is often incomplete and sketchy, this report is intended to serve as a basis for future, more detailed work that includes initial field inspection, detailed field and laboratory studies, and extrapolations to the subsurface

  7. Analysis of the rock mechanics properties of volcanic tuff units from Yucca Mountain, Nevada Test Site

    International Nuclear Information System (INIS)

    Price, R.H.

    1983-08-01

    Over two hundred fifty mechanical experiments have been run on samples of tuff from Yucca Mountain, Nevada Test Site. Cores from the Topopah Spring, Calico Hills, Bullfrog and Tram tuff units were deformed to collect data for an initial evaluation of mechanical (elastic and strength) properties of the potential horizons for emplacement of commercial nuclear wastes. The experimental conditions ranged in sample saturation from room dry to fully saturated, confining pressure from 0.1 to 20 MPa, pore pressure from 0.1 to 5 MPa, temperature from 23 to 200 0 C, and strain rate from 10 -7 to 10 -2 s -1 . These test data have been analyzed for variations in elastic and strength properties with changes in test conditions, and to study the effects of bulk-rock characteristics on mechanical properties. In addition to the site-specific data on Yucca Mountain tuff, mechanical test results on silicic tuff from Rainier Mesa, Nevada Test Site, are also discussed. These data both overlap and augment the Yucca Mountain tuff data, allowing more definitive conclusions to be reached, as well as providing data at some test conditions not covered by the site-specific tests

  8. LES of flow in the street canyon

    Science.gov (United States)

    Fuka, Vladimír; Brechler, Josef

    2012-04-01

    Results of computer simulation of flow over a series of street canyons are presented in this paper. The setup is adapted from an experimental study by [4] with two different shapes of buildings. The problem is simulated by an LES model CLMM (Charles University Large Eddy Microscale Model) and results are analysed using proper orthogonal decomposition and spectral analysis. The results in the channel (layout from the experiment) are compared with results with a free top boundary.

  9. New supply for canyon fire foam system

    International Nuclear Information System (INIS)

    Gainey, T.

    1995-01-01

    The raw water supply for the B-Plant Canyon fire foam system is being replaced. The 4 inche water supply line to the foam system is being rerouted from the 6 inches raw water line in the Pipe Gallery to the 10 inches raw water main in the Operating Gallery. This document states the acceptance criteria for the flushing and testing to be performed by the contractor

  10. Ventilation Processes in a Three-Dimensional Street Canyon

    Science.gov (United States)

    Nosek, Štěpán; Kukačka, Libor; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

    2016-05-01

    The ventilation processes in three different street canyons of variable roof geometry were investigated in a wind tunnel using a ground-level line source. All three street canyons were part of an urban-type array formed by courtyard-type buildings with pitched roofs. A constant roof height was used in the first case, while a variable roof height along the leeward or windward walls was simulated in the two other cases. All street-canyon models were exposed to a neutrally stratified flow with two approaching wind directions, perpendicular and oblique. The complexity of the flow and dispersion within the canyons of variable roof height was demonstrated for both wind directions. The relative pollutant removals and spatially-averaged concentrations within the canyons revealed that the model with constant roof height has higher re-emissions than models with variable roof heights. The nomenclature for the ventilation processes according to quadrant analysis of the pollutant flux was introduced. The venting of polluted air (positive fluctuations of both concentration and velocity) from the canyon increased when the wind direction changed from perpendicular to oblique, irrespective of the studied canyon model. Strong correlations (>0.5) between coherent structures and ventilation processes were found at roof level, irrespective of the canyon model and wind direction. This supports the idea that sweep and ejection events of momentum bring clean air in and detrain the polluted air from the street canyon, respectively.

  11. An investigation of the mechanical and hydrologic behavior of tuff fractures under saturated conditions

    International Nuclear Information System (INIS)

    Voss, C.F.; Shotwell, L.R.

    1990-04-01

    The mechanical and hydrologic behavior of natural fractures in a partially welded tuff rock were investigated. Tuff cores, each containing part of the same natural fracture oriented subparallel to the core axis, were subjected a range of stress and hydraulic gradients while simultaneously monitoring changes in the fracture aperture and volumetric flow rate. The fractures were tested in three configurations: intact, mated, and offset. Fracture deformation was nonlinear over the stress range tested with permanent deformation and hysteresis occurring with each loading cycle. The offset samples had larger permanent deformation and significantly reduced normal stiffness at lower stress levels. The cubic flow law appears to be valid for the relatively undisturbed tuff fractures at the scale tested. The cubic law did not explain the observed hydraulic behavior of the offset fractures. 6 refs., 10 figs., 2 tabs

  12. Mo and Ni Removal from Drinking Water Using Zeolitic Tuff from Jordan

    Directory of Open Access Journals (Sweden)

    Khalil M. Ibrahim

    2016-11-01

    Full Text Available Mo and Ni metals could be hazardous in natural waters. The initial Mo and Ni concentration in the sampled domestic drinking water of north Jordan is 550 and 110 μg/L, respectively. The efficiency of using natural faujasite–phillipsite and phillipsite–chabazite tuffs in removing Mo and Ni from contaminated drinking water was tested. Batch experiments using different weights of the adsorbent were conducted at different contact times to determine the optimum conditions. The maximal uptake capacity of Mo from drinking water was equivalent to 440–420 μg/g adsorbent. The maximum removal efficiency of Mo by faujasite–phillipsite, phillipsite–chabazite, and the modified surfactant phillipsite–chabazite tuffs were 80%, 76%, and 78%, respectively. The proportional relationship between contact time and removal efficiency of Ni from water samples was observed. The maximum removal efficiency of Ni by the zeolitic tuffs is up to 90% compared to the original groundwater sample.

  13. Evidence for a welded tuff in the Rhyolite of Calico Hills

    International Nuclear Information System (INIS)

    Dickerson, R.P.; Hunter, W.C.

    1994-01-01

    A welded pyroclastic deposit has been identified in the Rhyolite of Calico Hills near Yucca Mountain, Nevada, where only lava flows and nonwelded pyroclastic deposits were previously described. Field data from Fortymile Wash show that nonwelded, bedded tuff grades upward into partially welded massive ruff, and thence into densely welded vitrophyre. Petrographic data show a progressive decrease in inter- and intragranular porosity and amount of vapor-phase minerals, with increasing welding. Pumice fragments are first deformed, then develop diffuse boundaries which become increasingly obscure with progressive welding. The most densely welded rock is a perlitic vitrophyre. The origin of this welded tuff is not clear, as it could represent an ignimbrite or a tuff fused beneath a thick lava flow

  14. Stress corrosion cracking tests on high-level-waste container materials in simulated tuff repository environments

    International Nuclear Information System (INIS)

    Abraham, T.; Jain, H.; Soo, P.

    1986-06-01

    Types 304L, 316L, and 321 austenitic stainless steel and Incoloy 825 are being considered as candidate container materials for emplacing high-level waste in a tuff repository. The stress corrosion cracking susceptibility of these materials under simulated tuff repository conditions was evaluated by using the notched C-ring method. The tests were conducted in boiling synthetic groundwater as well as in the steam/air phase above the boiling solutions. All specimens were in contact with crushed Topopah Spring tuff. The investigation showed that microcracks are frequently observed after testing as a result of stress corrosion cracking or intergranular attack. Results showing changes in water chemistry during test are also presented

  15. Hydraulic Characterization of Overpressured Tuffs in Central Yucca Flat, Nevada Test Site, Nye County, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    K.J. Halford; R.J. Laczniak; D.L. Galloway

    2005-10-07

    A sequence of buried, bedded, air-fall tuffs has been used extensively as a host medium for underground nuclear tests detonated in the central part of Yucca Flat at the Nevada Test Site. Water levels within these bedded tuffs have been elevated hundreds of meters in areas where underground nuclear tests were detonated below the water table. Changes in the ground-water levels within these tuffs and changes in the rate and distribution of land-surface subsidence above these tuffs indicate that pore-fluid pressures have been slowly depressurizing since the cessation of nuclear testing in 1992. Declines in ground-water levels concurrent with regional land subsidence are explained by poroelastic deformation accompanying ground-water flow as fluids pressurized by underground nuclear detonations drain from the host tuffs into the overlying water table and underlying regional carbonate aquifer. A hydraulic conductivity of about 3 x 10-6 m/d and a specific storage of 9 x 10-6 m-1 are estimated using ground-water flow models. Cross-sectional and three-dimensional ground-water flow models were calibrated to measured water levels and to land-subsidence rates measured using Interferometric Synthetic Aperture Radar. Model results are consistent and indicate that about 2 million m3 of ground water flowed from the tuffs to the carbonate rock as a result of pressurization caused by underground nuclear testing. The annual rate of inflow into the carbonate rock averaged about 0.008 m/yr between 1962 and 2005, and declined from 0.005 m/yr in 2005 to 0.0005 m/yr by 2300.

  16. Lithostratigraphy of the Calico Hills Formation and Prow Pass Tuff (Crater Flat Group) at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Moyer, T.C.; Geslin, J.K.

    1995-01-01

    Lithostratigraphic relations within the Calico Hills Formation and Prow Pass Tuff (Crater Flat Group) were reconstructed from analysis of core samples and observation of outcrop exposures. The Calico Hills Formation is composed of five nonwelded pyroclastic units (each formed of one or more pyroclastic-flow deposits) that overlie an interval of bedded tuff and a basal volcaniclastic sandstone unit. The Prow Pass Tuff is divided into four pyroclastic units and an underlying interval of bedded tuff. The pyroclastic units of the Prow Pass Tuff are distinguished by the sizes and amounts of their pumice and lithic clasts and their degree of welding. Pyroclastic units of the Prow Pass Tuff are distinguished from those of the Calico Hills Formation by their phenocryst assemblage, chemical composition, and ubiquitous siltstone lithic clasts. Downhole resistivity tends to mirror the content of authigenic minerals, primarily zeolites, in both for-mations and may be useful for recognizing the vitric-zeolite boundary in the study area. Maps of zeolite distribution illustrate that the bedded tuff and basal sandstone units of the Calico Hills Formation are altered over a wider area than the pyroclastic units of both the Calico Hills Formation and the upper Prow Pass Tuff

  17. Lithostratigraphy of the Calico Hills Formation and Prow Pass Tuff (Crater Flat Group) at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, T.C.; Geslin, J.K. [Science Applications International Corp., Las Vegas, NV (United States)

    1995-07-01

    Lithostratigraphic relations within the Calico Hills Formation and Prow Pass Tuff (Crater Flat Group) were reconstructed from analysis of core samples and observation of outcrop exposures. The Calico Hills Formation is composed of five nonwelded pyroclastic units (each formed of one or more pyroclastic-flow deposits) that overlie an interval of bedded tuff and a basal volcaniclastic sandstone unit. The Prow Pass Tuff is divided into four pyroclastic units and an underlying interval of bedded tuff. The pyroclastic units of the Prow Pass Tuff are distinguished by the sizes and amounts of their pumice and lithic clasts and their degree of welding. Pyroclastic units of the Prow Pass Tuff are distinguished from those of the Calico Hills Formation by their phenocryst assemblage, chemical composition, and ubiquitous siltstone lithic clasts. Downhole resistivity tends to mirror the content of authigenic minerals, primarily zeolites, in both for-mations and may be useful for recognizing the vitric-zeolite boundary in the study area. Maps of zeolite distribution illustrate that the bedded tuff and basal sandstone units of the Calico Hills Formation are altered over a wider area than the pyroclastic units of both the Calico Hills Formation and the upper Prow Pass Tuff.

  18. Decay of Rhenish Tuffs in Dutch Monuments. Part 2 : Laboratory Experiments as a Basis for the Choice of Restoration Stone

    NARCIS (Netherlands)

    Van Hees, R.P.J.; Brendle, S.; Nijland, T.G.; De Haas, G.J.L.M.; Tolboom, H.J.

    2003-01-01

    Rhenish tuffs (Eifel, Germany), have been used as building material in the Netherlands since Roman times. They were the most important natural building stone in the Netherlands in early medieval times. In addition, tuff was used as raw material for production of trass, that served as a pozzolanic

  19. Decay of Rhenish Tuff in Dutch monuments. Part 2 : Laboratory experiments as a basis for the choice of restoration stone

    NARCIS (Netherlands)

    Hees, R.P.J. van; Brendle, S.; Nijland, T.G.; Haas, G.J.L.M. de; Tolboom, H.J.

    2003-01-01

    Rhenish tuffs (Eifel, Getmany), have been used as building material in the Netherlands since Roman times. They were the most important natural building stone in the Netherlands in early medieval times. In addition, tuff was used as raw material for production of trass, that served as a pozzolanic

  20. Some geochemical considerations for a potential repository site in tuff at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Erdal, B.R.; Bish, D.L.; Crowe, B.M.; Daniels, W.R.; Ogard, A.E.; Rundberg, R.S.; Vaniman, D.T.; Wolfsberg, K.

    1982-01-01

    The Nevada Nuclear Waste Storage Investigations, which is evaluating potential locations for a high-level waste repository at the Nevada Test Site and environs, is currently focusing its investigations on tuff, principally in Yucca Mountain, as a host rock. This paper discusses some of the geochemical investigations. Particular emphasis is placed on definition of some basic elements and necessary technical approaches for the geochemistry data acquisition and modeling program. Some site-specific tuff geochemical information that is important for site selection and repository performance will be identified and the current status of knowledge will then be discussed

  1. K-Ar age estimate for the KBS Tuff, East Turkana, Kenya

    International Nuclear Information System (INIS)

    McDougall, I.; Maier, R.; Sutherland-Hawkes, P.; Gleadow, A.J.W.

    1980-01-01

    Stone tools and numerous vertebrate fossils including hominids, have been found in close stratigraphic proximity to the KBS Tuff, whose age has been the subject of much debate. Concordant K-Ar ages, averaging 1.89 +- 0.01 Myr, are reported on anorthoclase phenocrysts from 13 pumice clasts collected from within the KBS Tuff or its correlatives. It is believed that this age is the best estimate currently available for the time of formation of this important marker horizon within the East Turkana Basin. (author)

  2. Sorption and desorption of remazol yellow by a Fe-zeolitic tuff

    International Nuclear Information System (INIS)

    Solache R, M. J.; Villalva C, R.; Diaz N, M. C.

    2010-01-01

    The adsorption of remazol yellow from aqueous solution was evaluated using a Fe-zeolitic tuff. The adsorbent was characterized by scanning electron microscopy, IR spectroscopy and X-ray diffraction. Sorption kinetic and isotherms were determined and the adsorption behavior was analyzed. Kinetic pseudo-second order and Langmuir-Freundlich models were successfully applied to the experimental results, indicating chemisorption on a heterogeneous material. The regeneration of the material was best accomplished by using a H 2 O 2 solution. The sorption capacity of the Fe-zeolitic tuff increased when the saturated samples were treated with a H 2O2 or FeCl 3 solution. (Author)

  3. Triaxial- and uniaxial-compression testing methods developed for extraction of pore water from unsaturated tuff, Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Mower, T.E.; Higgins, J.D. [Colorado School of Mines, Golden, CO (USA). Dept. of Geology and Geological Engineering; Yang, I.C. [Geological Survey, Denver, CO (USA). Water Resources Div.

    1989-12-31

    To support the study of hydrologic system in the unsaturated zone at Yucca Mountain, Nevada, two extraction methods were examined to obtain representative, uncontaminated pore-water samples from unsaturated tuff. Results indicate that triaxial compression, which uses a standard cell, can remove pore water from nonwelded tuff that has an initial moisture content greater than 11% by weight; uniaxial compression, which uses a specifically fabricated cell, can extract pore water from nonwelded tuff that has an initial moisture content greater than 8% and from welded tuff that has an initial moisture content greater than 6.5%. For the ambient moisture conditions of Yucca Mountain tuffs, uniaxial compression is the most efficient method of pore-water extraction. 12 refs., 7 figs., 2 tabs.

  4. AUV Mapping and ROV Exploration of Los Frailes Submarine Canyon, Cabo Pulmo National Marine Park, Baja California Sur, Mexico

    Science.gov (United States)

    Troni, G.; Caress, D. W.; Graves, D.; Thomas, H. J.; Thompson, D.; Barry, J. P.; Aburto-Oropeza, O.; Johnson, A. F.; Lundsten, L.

    2015-12-01

    Los Frailes submarine canyon is located at the south boundary of the Cabo Pulmo National Marine Park on the southeast tip of the Baja California Peninsula. During the Monterey Bay Aquarium Research Institute (MBARI) 2015 Gulf of California expedition we used an autonomous underwater vehicle (AUV) to map this canyon from 50 m to 450 m depths, and then explored the canyon with a small remotely operated vehicle (ROV). This three day R/V Rachel Carson cruise was a collaboration with the Center for Marine Biodiversity and Conservation at Scripps Institution of Oceanography and the Centro para la Biodiversidad Marina y la Conservación in La Paz. The MBARI AUV D. Allan B. collected high resolution bathymetry, sidescan, and subbottom profiles of Los Frailes submarine canyon and part of the north Cabo Pulmo deep reef. In order to safely generate a 1-m lateral resolution multibeam bathymetry map in the nearshore high relief terrain, the mapping operations consisted of an initial short survey following the 100-m isobath followed by a series of short, incremental AUV missions located on the deep edge of the new AUV bathymetry. The MBARI Mini-ROV was used to explore the submarine canyon within the detailed map created by the MBARI AUV. The Mini-ROV is a 1.2-m-long, 350 kg, 1,500-m-depth-rated ROV designed and constructed by MBARI. It is controlled by six 600-watt thrusters and is equipped with a high-definition video camera and navigation sensors. This small ROV carries less accurate, lower cost navigation sensors than larger vehicles. We implemented new algorithms to localize combining Doppler velocity log sensor data and low-cost MEMS-based inertial sensor data with sporadic ultra-short baseline position measurements to provide a high accuracy position estimation. The navigation performance allowed us to colocate the ROV video imagery with the 1-m resolution bathymetric map of the submarine canyon. Upper Los Frailes Canyon is rugged and, aside from small sand pockets along

  5. 78 FR 7810 - Glen Canyon Dam Adaptive Management Work Group

    Science.gov (United States)

    2013-02-04

    ... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group... Adaptive Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning..., the AMWG, a technical work group (TWG), a Grand Canyon Monitoring and Research Center, and independent...

  6. 78 FR 21415 - Glen Canyon Dam Adaptive Management Work Group

    Science.gov (United States)

    2013-04-10

    ... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group... Adaptive Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning... Federal advisory committee, the AMWG, a technical work group, a Grand Canyon Monitoring and Research...

  7. 75 FR 34476 - Glen Canyon Dam Adaptive Management Work Group

    Science.gov (United States)

    2010-06-17

    ... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group... Management Work Group. The purpose of the Adaptive Management Work Group is to advise and to provide... of the Glen Canyon Dam Adaptive Management Work Group is in the public interest in connection with...

  8. 76 FR 24516 - Glen Canyon Dam Adaptive Management Work Group

    Science.gov (United States)

    2011-05-02

    ... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group... Adaptive Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning..., the AMWG, a technical work group (TWG), a Grand Canyon Monitoring and Research Center, and independent...

  9. Modelling the air flow in symmetric and asymmetric street canyons

    Energy Technology Data Exchange (ETDEWEB)

    Santiago, J.L.; Martin, F. [Research Center for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Fossil Fuels Dept., Numerical Simulation and Modelling Program

    2004-07-01

    In recent years a large amount of research has been conducted on urban scale and street canyon. Control of air quality inside cities is important for human health. To achieve this objective, street canyon modelling plays a significant role. Pollutant dispersion inside canyons are determined by wind flow around this complex geometry. Experimental investigations have been made by means of field measurements such as Vachon, G. et al. or wind tunnel experiences as Meroney, R.N. et al. or Kastner-Klein, P. and E.J. Plate. In many of these researches, they have used CFD models in several configurations, for instance Assimakopoulos, V.D. et al. or Sini, J.-F. et al. These models are based on a numerical resolution of Navier-Stokes equations with a turbulence closure. In this study, the aim is contribute to the understanding of air circulation inside street canyons. In order to achieve this purpose, several configurations of canyons are investigated. Two-dimensional sequences of real-scale street canyons (order to obstacles height is meters) with different features (symmetric canyons and asymmetric canyons forming step-up and step-down notch configurations) are simulated. These general configurations are modified to investigate some parameters such as aspect ratio, W/H, where W is the width of street and H is the height of buildings. Flows with high Reynolds numbers are modelling. FLUENT CFD software is used. (orig.)

  10. Implications of tree planting on pollutant dispersion in street canyons

    NARCIS (Netherlands)

    Gromke, C.B.; Ruck, B.

    2009-01-01

    Traffic pollutant dispersion processes inside urban street canyons with avenue-like tree planting have been studied in wind tunnel experiments. Tree planting of different crown porosities and their effects on the pollutant concentrations at the canyon walls have been investigated for wind

  11. Geology and geomorphology of the Lower Deschutes River Canyon, Oregon.

    Science.gov (United States)

    Robin A. Beebee; Jim E. O' Connor; Gordon E. Grant

    2002-01-01

    This field guide is designed for geologists floating the approximately 80 kilometers (50 miles) of the Deschutes River from the Pelton-Round Butte Dam Complex west of Madras to Maupin, Oregon. The first section of the guide is a geologic timeline tracing the formation of the units that compose the canyon walls and the incision of the present canyon. The second section...

  12. Modeling the Effect of Wider Canyons on Urban Heating

    Directory of Open Access Journals (Sweden)

    Rizwan Ahmed Memon

    2011-04-01

    Full Text Available The k-? turbulence model is adopted in this study to simulate the impact of street canyon AR (Aspect Ratios on heating within street canyon. The two-dimensional model was validated for RANS (Reynolds Averaged Navier Stokes and energy transport equations. The validation process confirms that the results of the model for airtemperature and wind speed could be trusted. The application of the said model is carried out to ideal street canyons of ARs (ratio of building-height-to-street-width from 0.4 to 2 with the same boundary conditions. Notably, street canyon aspect ratio was calculated by varying the street width while keeping the building height constant. Results show that the weighted-average-air-temperature within AR 0.4 was around 0.8% (i.e. 2.4K higher than that within AR 2.0. Conversely, there was strong correlation (i.e., R2>0.9 between air temperature within the street canyon and street canyon AR. Results demonstrate stronger influence of vertical velocity on heating within street canyon. Evidently, increased vertical velocity decreased the temperatures. Conversely, temperatures were higher along the leeward side of the canyon in lower ARs.

  13. Perspective view over the Grand Canyon, Arizona

    Science.gov (United States)

    2001-01-01

    This simulated true color perspective view over the Grand Canyon was created from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data acquired on May 12, 2000. The Grand Canyon Village is in the lower foreground; the Bright Angel Trail crosses the Tonto Platform, before dropping down to the Colorado Village and then to the Phantom Ranch (green area across the river). Bright Angel Canyon and the North Rim dominate the view. At the top center of the image the dark blue area with light blue haze is an active forest fire. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate. Size: 5 km in foreground to 40 km Location: 36.3 degrees north latitude, 112 degrees west longitude Orientation: North-northeast at top Original Data Resolution: ASTER 15 meters Dates Acquired: May 12, 2000

  14. Big Canyon Creek Ecological Restoration Strategy.

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, Lynn; Richardson, Shannon

    2007-10-01

    He-yey, Nez Perce for steelhead or rainbow trout (Oncorhynchus mykiss), are a culturally and ecologically significant resource within the Big Canyon Creek watershed; they are also part of the federally listed Snake River Basin Steelhead DPS. The majority of the Big Canyon Creek drainage is considered critical habitat for that DPS as well as for the federally listed Snake River fall chinook (Oncorhynchus tshawytscha) ESU. The Nez Perce Soil and Water Conservation District (District) and the Nez Perce Tribe Department of Fisheries Resources Management-Watershed (Tribe), in an effort to support the continued existence of these and other aquatic species, have developed this document to direct funding toward priority restoration projects in priority areas for the Big Canyon Creek watershed. In order to achieve this, the District and the Tribe: (1) Developed a working group and technical team composed of managers from a variety of stakeholders within the basin; (2) Established geographically distinct sub-watershed areas called Assessment Units (AUs); (3) Created a prioritization framework for the AUs and prioritized them; and (4) Developed treatment strategies to utilize within the prioritized AUs. Assessment Units were delineated by significant shifts in sampled juvenile O. mykiss (steelhead/rainbow trout) densities, which were found to fall at fish passage barriers. The prioritization framework considered four aspects critical to determining the relative importance of performing restoration in a certain area: density of critical fish species, physical condition of the AU, water quantity, and water quality. It was established, through vigorous data analysis within these four areas, that the geographic priority areas for restoration within the Big Canyon Creek watershed are Big Canyon Creek from stream km 45.5 to the headwaters, Little Canyon from km 15 to 30, the mainstem corridors of Big Canyon (mouth to 7km) and Little Canyon (mouth to 7km). The District and the Tribe

  15. The Black Canyon of the Gunnison: Today and Yesterday

    Science.gov (United States)

    Hansen, Wallace R.

    1965-01-01

    Since the early visit of Captain John William Gunnison in the middle of the last century, the Black Canyon of the Gunnison has stirred mixed apprehension and wonder in the hearts of its viewers. It ranks high among the more awesome gorges of North America. Many great western canyons are as well remembered for their brightly colored walls as for their airy depths. Not so the Black Canyon. Though it is assuredly not black, the dark-gray tones of its walls and the hazy shadows of its gloomy depths join together to make its name well deserved. Its name conveys an impression, not a picture. After the first emotional impact of the canyon, the same questions come to the minds of most reflective viewers and in about the following order: How deep is the Black Canyon, how wide, how does it compare with other canyons, what are the rocks, how did it form, and how long did it take? Several western canyons exceed the Black Canyon in overall size. Some are longer; some are deeper; some are narrower; and a few have walls as steep. But no other canyon in North American combines the depth, narrowness, sheerness, and somber countenance of the Black Canyon. In many places the Black Canyon is as deep as it is wide. Between The Narrows and Chasm View in the Black Canyon of the Gunnison National Monument (fig. 15) it is much deeper than wide. Average depth in the monument is about 2,000 feet, ranging from a maximum of about 2,700 feet, north of Warner Point (which also is the greatest depth anywhere in the canyon), to a minimum of about 1,750 feet at The Narrows. The stretch of canyon between Pulpit Rock and Chasm View, including The Narrows, though the shallowest in the monument, is also the narrowest, has some of the steepest walls, and is, therefore, among the most impressive segments of the canyon (fig. 3). Profiles of several well-known western canyons are shown in figure 1. Deepest of these by far is Hells Canyon of the Snake, on the Idaho-Oregon border. Clearly, it dwarfs the

  16. Dispersion and photochemical evolution of reactive pollutants in street canyons

    Science.gov (United States)

    Kwak, Kyung-Hwan; Baik, Jong-Jin; Lee, Kwang-Yeon

    2013-05-01

    Dispersion and photochemical evolution of reactive pollutants in street canyons with canyon aspect ratios of 1 and 2 are investigated using a computational fluid dynamics (CFD) model coupled with the carbon bond mechanism IV (CBM-IV). Photochemical ages of NOx and VOC are expressed as a function of the NO2-to-NOx and toluene-to-xylene ratios, respectively. These are found to be useful for analyzing the O3 and OH oxidation processes in the street canyons. The OH oxidation process (O3 oxidation process) is more pronounced in the upper (lower) region of the street canyon with a canyon aspect ratio of 2, which is characterized by more (less) aged air. In the upper region of the street canyon, O3 is chemically produced as well as transported downward across the roof level, whereas O3 is chemically reduced in the lower region of the street canyon. The O3 chemical production is generally favorable when the normalized photochemical ages of NOx and VOC are larger than 0.55 and 0.28, respectively. The sensitivities of O3 chemical characteristics to NOx and VOC emission rates, photolysis rate, and ambient wind speed are examined for the lower and upper regions of the street canyon with a canyon aspect ratio of 2. The O3 concentration and the O3 chemical production rate divided by the O3 concentration increase as the NOx emission rate decreases and the VOC emission rate and photolysis rate increase. The O3 concentration is less sensitive to the ambient wind speed than to other factors considered. The relative importance of the OH oxidation process compared to the O3 oxidation process increases with increasing NOx emission rate and photolysis rate and decreasing VOC emission rate. In this study, both O3 and OH oxidation processes are found to be important in street-canyon scale chemistry. The methodology of estimating the photochemical ages can potentially be adopted to neighborhood scale chemistry.

  17. Performance prediction of mechanical excavators from linear cutter tests on Yucca Mountain welded tuffs

    International Nuclear Information System (INIS)

    Gertsch, R.; Ozdemir, L.

    1992-09-01

    The performances of mechanical excavators are predicted for excavations in welded tuff. Emphasis is given to tunnel boring machine evaluations based on linear cutting machine test data obtained on samples of Topopah Spring welded tuff. The tests involve measurement of forces as cutters are applied to the rock surface at certain spacing and penetrations. Two disc and two point-attack cutters representing currently available technology are thus evaluated. The performance predictions based on these direct experimental measurements are believed to be more accurate than any previous values for mechanical excavation of welded tuff. The calculations of performance are predicated on minimizing the amount of energy required to excavate the welded tuff. Specific energy decreases with increasing spacing and penetration, and reaches its lowest at the widest spacing and deepest penetration used in this test program. Using the force, spacing, and penetration data from this experimental program, the thrust, torque, power, and rate of penetration are calculated for several types of mechanical excavators. The results of this study show that the candidate excavators will require higher torque and power than heretofore estimated

  18. Maximum likelihood Bayesian averaging of airflow models in unsaturated fractured tuff using Occam and variance windows

    NARCIS (Netherlands)

    Morales-Casique, E.; Neuman, S.P.; Vesselinov, V.V.

    2010-01-01

    We use log permeability and porosity data obtained from single-hole pneumatic packer tests in six boreholes drilled into unsaturated fractured tuff near Superior, Arizona, to postulate, calibrate and compare five alternative variogram models (exponential, exponential with linear drift, power,

  19. Technology teachers as researchers : philosophical and empirical technology education studies in the Swedish TUFF Research School

    NARCIS (Netherlands)

    Skogh, I.B.; Vries, de M.J.

    2013-01-01

    This book presents the scientific output of the TUFF research school in Sweden. In this school, a group of active teachers worked together on a series of educational research studies. All of those studies were related to the teaching about technology and engineering. The research program consisted

  20. TRM performance prediction in Yucca Mountain welded tuff from linear cutter tests

    International Nuclear Information System (INIS)

    Gertsch, R.; Ozdemir, L.; Gertsch, L.

    1992-01-01

    Performance predictions were developed for tunnel boring machines operating in welded tuff for the construction of the experimental study facility and the potential nuclear waste repository at Yucca Mountain. The predictions were based on test data obtained from an extensive series of linear cutting tests performed on samples of Topopah Spring welded tuff from the Yucca Mountain Project site. Using the cutter force, spacing, and penetration data from the experimental program, the thrust, torque, power, and rate of penetration were estimated for a 25 ft diameter tunnel boring machine (TBM) operating in welded tuff. Guidelines were developed for the optimal design of the TBM cutterhead to achieve high production rates at the lowest possible excavation costs. The results show that the Topopah Spring welded tuff (TSw2) can be excavated at relatively high rates of advance with state-of-the-art TBMs. The results also show, however, that the TBM torque and power requirements will be higher than estimated based on rock physical properties and past tunneling experience in rock formations of similar strength

  1. Triaxial-compression extraction of pore water from unsaturated tuff, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Yang, I.C.; Turner, A.K.; Sayre, T.M.; Montazer, P.

    1988-01-01

    The purpose of this experiment was to design and validate methods for extracting uncontaminated pore water from nonwelded parts of this tuff. Pore water is needed for chemical analysis to help characterize the local hydrologic system. A standard Hoek-Franklin triaxial cell was modified to create a chemically inert pore-water-extraction system. Experimentation was designed to determine the optimum stress and duration of triaxial compression for efficient extraction of uncontaminated pore water. Experimental stress paths consisted of a series of increasing stress levels. Trial axial stress levels ranged from 41 to 190 megapascals with lateral confining stresses of 34 to 69 megapascals. The duration of compression at any given stress level lasted from 10 minutes to 15 hours. A total of 40 experimental extraction trials were made. Tuff samples used in these tests were collected from drill-hole core from the Paintbrush nonwelded unit at Yucca Mountain. Pore water was extracted from tuff samples that had a water content greater than 13 percent by weight. Two stress paths have been determined to be applicable for future pore-water extraction from nonwelded tuff at Yucca Mountain. The initial water content of a sample affects the selection of an appropriate period of compression. 39 refs., 55 figs

  2. Occurrence of rhyolytic tuffs at deep sea drilling project site 219 on the Laccadive Ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Siddiquie, H.N.; Sukheswala, R.N.

    A study of thin sections from the lower and middle parts of Unit 5 (Paleocene) from Site 219 shows that these largely consist of acidic or rhyolitic tuffs. The overlying limestones in Unit 5 (Paleocene) and Unit 4 (Lower Eocene) also contain...

  3. Corrosion testing of type 304L stainless steel in tuff groundwater environments

    International Nuclear Information System (INIS)

    Westerman, R.E.; Pitman, S.G.; Haberman, J.H.

    1987-11-01

    The stress-corrosion cracking (SCC) resistance of Type 304L stainless steel (SS) to elevated temperatures in tuff rock and tuff groundwater environments was determined under irradiated and nonirradiated conditions using U-bend specimens and slow-strain-rate tests. The steel was tested both in the solution-annealed condition and after sensitization heat treatments. The material was found to be susceptible to SCC in both the solution-annealed and solution-annealed-and-sensitized conditions when exposed to an irradiated crushed tuff rock environment containing air and water vapor at 90 0 C. A similar exposure at 50 0 C did not result in failure after a 25-month test duration. Specimens of sensitized 304 SS conditioned with a variety of sensitization heat treatments resisted failure during a test of 1-year duration in which a nonirradiated environment of tuff rock and groundwater held at 200 0 C was allowed to boil to dryness on a cyclical basis. All specimens of sensitized 304 SS exposed to this environment failed. Slow-strain-rate studies were performed on 304L, 304, and 316L SS specimens. The 304L SS was tested in J-13 well water at 150 0 C, and the 316L SS at 95 0 C. Neither material showed evidence of SCC in these tests. Sensitized 304 SS did exhibit SCC in J-13 well water in tests conducted at 150 0 C. 12 refs., 27 figs., 13 tabs

  4. Use of Rhenish tuff and trass in the Netherlands in the past two millenia

    NARCIS (Netherlands)

    Nijland, T.G.; Hees, R.P.J. van

    2017-01-01

    Occasionally, a profound but distant connection between volcanos and culture exists. This is the case for the volcanic Eifel region in Germany and historic construction in the Netherlands, with the river Rhine as physical and enabling connection. Volcanic tuff from the Eifel comprises a significant

  5. Version I of the users manual for the Tuff Data Base Interface

    International Nuclear Information System (INIS)

    Langkopf, B.S.; Satter, B.J.; Welch, E.P.

    1985-04-01

    The Nevada Nuclear Waste Storage Investigations (NNWSI) project, managed by the Nevada Operations Office of the US Department of Energy, is investigating the feasibility of locating a repository at Yucca Mountain on and adjacent to the Nevada Test Site (NTS) in southern Nevada. A part of this investigation includes obtaining physical properties from laboratory tests on samples from Yucca Mountain and field tests of the in situ tuffs at Yucca Mountain. A computerized data base has been developed to store this data in a centralized location. The data base is stored on the Cyber 170/855 computer at Sandia using the System 2000 Data Base Management software. A user-friendly interface, the Tuff Data Base Interface, is being developed to allow NNWSI participants to retrieve information from the Tuff Data Base directly. The Interface gives NNWSI users a great deal of flexibility in retrieving portions of the Data Base. This report is an interim users manual for the Tuff Data Base Interface, as of August 1984. It gives basic instructions on accessing the Sandia computing system and explains the Interface on a question-by-question basis

  6. Evenly-spaced columns in the Bishop Tuff as relicts of hydrothermal convection

    Science.gov (United States)

    Randolph-Flagg, N. G.; Breen, S. J.; Hernandez, A.; Self, S.; Manga, M.

    2015-12-01

    A few square km of the Bishop Tuff in eastern California, USA have evenly spaced erosional columns. These columns are more resistant to erosion due to the precipitation of the low-temperature zeolite (120-200 ºC), mordenite, which is not found in the surrounding tuff. Similar features observed in the Bandelier Tuff were hypothesized to form when cold water from above infiltrated into the still-hot tuff interior. This water would become gravitationally unstable and produced convection with steam upwellings and liquid water downwellings. These downwellings became cemented with mordenite while the upwellings were too dry for chemical reactions. We use two methods to quantitatively assess this hypothesis. First, scaling that ignores the effects of latent heat and mineral precipitation suggests the Rayleigh number (Ra, a measure of convective vigor) for this system is ~103 well above the critical Ra of 4π2. Second, to account for the effect of multiphase flow and latent heat, we use two-dimensional numerical models in the finite difference code HYDROTHERM. We find that the geometry of flow is consistent with field observations and confirm that geometry is sensitive to permeability and topography. These tests suggest a few things about low-pressure hydrothermal systems. 1) The geometry of at least some convection appears to be broadly captured by linear stability theory that ignores reactive transport, heterogeneity of host rock, and the effects of latent heat. 2) Topographic flow sets the wavelength of convection meaning that these columns formed somewhere without topography—probably a lake. Finally, these observations imply a wet paleoclimate in the Eastern Sierra namely that, in the aftermath of the Long Valley eruption, either rain or snow was able to pool in the caldera before the tuff cooled on the order of a hundred years after the eruption.

  7. The Tala Tuff, La Primavera caldera Mexico. Pre-eruptive conditions and magma processes before eruption

    Science.gov (United States)

    Sosa-Ceballos, G.

    2015-12-01

    La Primavera caldera, Jalisco Mexico, is a Pleistocenic volcanic structure formed by dome complexes and multiple pyroclastic flows and fall deposits. It is located at the intersection of the Chapala, Colima, and Tepic grabens in western Mexico. The first volcanic activity associated to La Primavera started ~0.1 Ma with the emission of pre-caldera lavas. The caldera collapse occurred 95 ka and is associated to the eruption of ~20 km3of pumice flows known as the Tala tuff (Mahood 1980). The border of the caldera was replaced by a series of domes dated in 75-30 ky, which partially filled the inner depression of the caldera with pyroclastic flows and falls. For more than a decade the Federal Commission of Electricity in Mexico (CFE) has prospected and evaluated the geothermal potential of the Cerritos Colorados project at La Primavera caldera. In order to better understand the plumbing system that tapped the Tala tuff and to investigate its relation with the potential geothermal field at La Primavera we performed a series of hydrothermal experiments and studied melt inclusions hosted in quartz phenocrysts by Fourier Infra red stectroscopy (FTIR). Although some post caldera products at La Primavera contain fayalite and quartz (suggesting QFM conditions) the Tala tuff does not contain fayalite and we ran experiments under NNO conditions. The absence of titanomagnetite does not allowed us to calculate pre-eruptive temperature. However, the stability of quartz and plagioclase, which are natural phases, suggest that temperature should be less than 750 °C at a pressure of 200 MPa. The analyses of H2O and CO2 dissolved in melt inclusions yielded concentrations of 2-5 wt.% and 50-100 ppm respectively. This data confirm that the pre-eruptive pressure of the Tala tuff is ~200 MPa and in addition to major elements compositions suggest that the Tala tuff is either, compositionally zoned or mixed with other magma just prior to eruption.

  8. Chloride Diffusion and Acid Resistance of Concrete Containing Zeolite and Tuff as Partial Replacements of Cement and Sand.

    Science.gov (United States)

    Mohseni, Ehsan; Tang, Waiching; Cui, Hongzhi

    2017-03-31

    In this paper, the properties of concrete containing zeolite and tuff as partial replacements of cement and sand were studied. The compressive strength, water absorption, chloride ion diffusion and resistance to acid environments of concretes made with zeolite at proportions of 10% and 15% of binder and tuff at ratios of 5%, 10% and 15% of fine aggregate were investigated. The results showed that the compressive strength of samples with zeolite and tuff increased considerably. In general, the concrete strength increased with increasing tuff content, and the strength was further improved when cement was replaced by zeolite. According to the water absorption results, specimens with zeolite showed the lowest water absorption values. With the incorporation of tuff and zeolite, the chloride resistance of specimens was enhanced significantly. In terms of the water absorption and chloride diffusion results, the most favorable replacement of cement and sand was 10% zeolite and 15% tuff, respectively. However, the resistance to acid attack reduced due to the absorbing characteristic and calcareous nature of the tuff.

  9. Morphodynamic Model of Submarine Canyon Incision by Sandblasting

    Science.gov (United States)

    Zhang, L.; Parker, G.; Izumi, N.; Cartigny, M.; Li, T.; Wang, G.

    2017-12-01

    Submarine canyons are carved by turbidity currents under the deep sea. As opposed to subaerial canyons, the relevant processes are not easy to observe directly. Turbidity currents are bottom-hugging sediment gravity flows of that can incise or deposit on the seafloor to create submarine canyons or fans. The triggers of turbidity currents can be storms, edge waves, internal waves, canyon wall sapping, delta failure, breaching and hyperpycnal flows. The formation and evolution mechanisms of submarine canyons are similar to those of subaerial canyons, but have substantial differences. For example, sandblasting, rather than wear due to colliding gravel clasts is more likely to be the mechanism of bedrock incision. Submarine canyons incise downward, and often develop meander bends and levees within the canyon, so defining "fairways". Here we propose a simple model for canyon incision. The starting point of our model is the Macro Roughness Saltation Abrasion Alluviation model of Zhang et al. [2015], designed for bedrock incision by gravel clasts in mixed bedrock-alluvial rivers. We adapt this formulation to consider sandblasting as a means of wear. We use a layer-averaged model for turbidity current dynamics. The current contains a mixture of mud, which helps drive the flow but which does not cause incision, and sand, which is the agent of incision. We show that the model can successfully model channel downcutting, and indeed illustrate the early formation of net incisional cyclic steps, i.e. upstream-migrating undulations on the bed associated with transcritical (in the Froude sense) flow. These steps can be expected to abet the process of incision.

  10. Deposition and diagenesis of the Brushy Basin Member and upper part of the Westwater Canyon member of the Morrison Formation, San Juan Basin, New Mexico

    International Nuclear Information System (INIS)

    Bell, T.E.

    1986-01-01

    The Brushy Basin Member and the upper part of the Westwater Canyon Member of the Morrison Formation in northwest New Mexico are nonmarine sedimentary rocks of Late Jurassic age. This stratigraphic interval consists of as many as four lithofacies deposited in fluvial and playa-lake environments. Lithofacies A is composed of crossbed feldspathic sandstone and was deposited by braided streams on an alluvial plain. Lithofacies B is composed of crossbedded feldspathic sandstone and tuffaceous mudstone, and was deposited by braided and anastomosing streams at the distal end of the alluvial plain. Lithofacies C is composed of calcareous, tuffaceous mudstone and was deposited on a mudflat between the alluvial plain and a playa lake. Lithofacies D is composed of zeolitic, tuffaceous mudstone and was deposited in a playa lake. The distribution of diagenetic facies in mudstones and tuffs in the Brushy Basin Member and upper part of the Westwater Canyon Member reflects the pH and salinity gradients common to fluvial/playa-lake systems. The abundant vitric ash in the sediments reacted to form montmorillonite in the fluvial facies. Calcite and montmorillonite were the reaction products where the fluvial and outermost playa facies met. Vitric ash reacted to form clinoptilolite and heulandite along the playa margins. In the center of the playa facies, analcime replaced clinoptilolite, an early zeolite. These early diagenetic minerals were replaced by albite, quartz, and mixed-layer illitemontmorillonite where the Brushy Basin Member and upper part of the Westwater Canyon Member have been deeply buried in the San Juan basin

  11. Outage risk reduction at Diablo Canyon

    International Nuclear Information System (INIS)

    Burnett, Tobias W.T.; Eugene Newman, C.

    2004-01-01

    A formal risk reduction program was conducted at the Diablo Canyon Nuclear Generating plant as part of EPRI's Outage Risk Assessment and Management Program. The program began with a probabilistic and deterministic assessment of the frequency of core coolant boiling and core uncovery during shutdown operations. This step identified important contributors to risk, periods of high vulnerability, and potential mechanisms for reducing risk. Next, recovery strategies were evaluated and procedures, training, and outage schedules modified. Twelve risk reduction enhancements were developed and implemented. These enhancements and their impact are described in this paper. These enhancements reduced the calculated risk of core uncovery by about a factor of four for a refueling outage without lengthening the outage schedule; increased the outage efficiency, contributing to completing 11 days ahead of schedule; and helped to earn the highest achievable SALP rating from the NRC. (author)

  12. Radionuclides at the Hudson Canyon disposal site

    International Nuclear Information System (INIS)

    Schell, W.R.; Nevissi, A.E.

    1983-01-01

    A sampling and analytical program was initiated in June 1978 to measure radionuclides in water, sediments, and biota collected at the deepwater (4000 m) radioactive waste disposal site at the mouth of the Hudson Canyon 350km off New York Harbor in the western Atlantic Ocean. Plutonium, americium, cesium, strontium, and uranium series isotopes were measured in selected samples; the /sup 210/Pb data were used to give sedimentation and mixing rates in the upper sediment layers. The results showed that /sup 137/Cs, /sup 239,240/Pu, and /sup 238/Pu were found at low concentrations in the skin, viscera, and stomach contents for some of the fish collected. Significant concentrations of /sup 241/Am were found in tissues of the common rattail Coryphaenoides (Macrouridae) collected at the disposal site, suggesting a local source for this radionuclide and biological accumulation. The edible muscle of this fish contained less than 2.6 x 10/sup -5/ Bq g/sup -1/ (dry wt) of /sup 239,240/Pu. Radionuclides measured in sediment-core profiles showed that mixing occurred to depths of 16 cm and that variable sedimentation or mixing rates, or both, exist at 4000 m deep. Radionuclide deposition near the canisters was not found to be significantly higher than the expected fallout levels at 4000 m deep. At the mouth of the Hudson Canyon variable sedimentation and mixing rates were found using the natural unsupported /sup 210/Pb tracer values; these variable rates were attributed to sediment transport by the currents and to bioturbation

  13. Distributions and habitat associations of deep-water corals in Norfolk and Baltimore Canyons, Mid-Atlantic Bight, USA

    NARCIS (Netherlands)

    Brooke, S.D.; Watts, M.W.; Heil, A.D.; Rhode, M.; Mienis, F.; Duineveld, G.C.A.; Davies, A.J.; Ross, S.W.

    2017-01-01

    A multi-disciplinary study of two major submarine canyons, Baltimore Canyon and Norfolk Canyon, off the US mid-Atlantic coast focused on the ecology and biology of canyon habitats, particularly those supporting deep-sea corals. Historical data on deep-sea corals from these canyons were sparse with

  14. Rose Canyon Sustainable Aquaculture Project, San Diego, CA

    Science.gov (United States)

    Documents related to EPA's preparation of an Environmental Assessment (EA) to analyze the potential impacts related to the issuance of a National Pollutant Discharge Elimination System (NPDES) permit for the Rose Canyon Sustainable Aquaculture Project.

  15. Habitat Mapping Cruise - Hudson Canyon (HB0904, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Objectives are to: 1) perform multibeam mapping of transitional and deepwater habitats in Hudson Canyon (off New Jersey) with the National Institute of Undersea...

  16. H Canyon Processing In Correlation With FH Analytical Labs

    International Nuclear Information System (INIS)

    Weinheimer, E.

    2012-01-01

    Management of radioactive chemical waste can be a complicated business. H Canyon and F/H Analytical Labs are two facilities present at the Savannah River Site in Aiken, SC that are at the forefront. In fact H Canyon is the only large-scale radiochemical processing facility in the United States and this processing is only enhanced by the aid given from F/H Analytical Labs. As H Canyon processes incoming materials, F/H Labs provide support through a variety of chemical analyses. Necessary checks of the chemical makeup, processing, and accountability of the samples taken from H Canyon process tanks are performed at the labs along with further checks on waste leaving the canyon after processing. Used nuclear material taken in by the canyon is actually not waste. Only a small portion of the radioactive material itself is actually consumed in nuclear reactors. As a result various radioactive elements such as Uranium, Plutonium and Neptunium are commonly found in waste and may be useful to recover. Specific processing is needed to allow for separation of these products from the waste. This is H Canyon's specialty. Furthermore, H Canyon has the capacity to initiate the process for weapons-grade nuclear material to be converted into nuclear fuel. This is one of the main campaigns being set up for the fall of 2012. Once usable material is separated and purified of impurities such as fission products, it can be converted to an oxide and ultimately turned into commercial fuel. The processing of weapons-grade material for commercial fuel is important in the necessary disposition of plutonium. Another processing campaign to start in the fall in H Canyon involves the reprocessing of used nuclear fuel for disposal in improved containment units. The importance of this campaign involves the proper disposal of nuclear waste in order to ensure the safety and well-being of future generations and the environment. As processing proceeds in the fall, H Canyon will have a substantial

  17. Experiences of fitting isotherms to data from batch sorption experiments for radionuclides on tuffs

    International Nuclear Information System (INIS)

    Polzer, W.L.; Fuentes, H.R.

    1989-11-01

    Laboratory experiments have been performed on the sorption of radionuclides on tuff as site characterization information for the Yucca Mountain Project. This paper presents general observations on the results of curve-fitting of sorption data by isotherm equations and the effects of experimental variables on their regressional analysis. Observations are specific to the effectiveness and problems associated with fitting isotherms, the calculation and value of isotherm parameters, and the significance of experimental variables such as replication, particle size, mode of sorption, and mineralogy. These observations are important in the design of laboratory experiments to ensure that collected data are adequate for effectively characterizing sorption of radionuclides on tuffs or other materials. 13 refs., 2 figs., 4 tabs

  18. Criticality characteristics of mixtures of plutonium, silicon dioxide, Nevada tuff, and water

    International Nuclear Information System (INIS)

    Sanchez, R.G.; Myers, W.; Stratton, W.

    1996-01-01

    The major objective of this study has been to examine the possibility of a nuclear explosion should 50 to 100 kg of plutonium be mixed with SiO 2 , vitrified, placed within a heavy steel container, and buried in the material known as Nevada tuff. To accomplish this objective, the authors have created a survey of critical states or configurations of mixtures of plutonium, SiO 2 , tuff, and water and examined these data to determine those configurations that might be unstable or autocatalytic. They have identified regions of criticality instability with the possibility of autocatalytic power behavior. Autocatalytic behavior is possible but improbable, for a very limited range of wet systems

  19. The reaction of glass during gamma irradiation in a saturated tuff environment

    International Nuclear Information System (INIS)

    Ebert, W.L.; Bates, J.K.; Gerding, T.J.

    1990-05-01

    The reaction between tuffaceous groundwater and actinide-doped SRL 165 and PNL 76-68 type glasses in a gamma radiation field has been studied at 90 degree C for periods up to 278 days. The primary effect of the radiation field was the acidification of the leachate through the production of nitrogen acids. Acidification of the leachate was limited by bicarbonate in the groundwater, for all exposures tested. Nonirradiated experiments were performed to represent the lowest limit of radiation exposure. Both irradiated and nonirradiated experiments were performed with and without a tuff monolith present in the reaction vessel. Neither irradiation nor the presence of tuff had a major effect on the extent of glass reaction as measured by the leachate concentrations of various glass species or analysis of the reacted glass surfaces. This report discusses the results of leaching experiments performed in a gamma radiation field and in the absence of a radiation field. 28 refs., 47 figs., 11 tabs

  20. Strontium isotope evolution of pore water and calcite in the Topopah Spring Tuff, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Marshall, Brian D.; Futa, Kiyoto

    2001-01-01

    Pore water in the Topopah Spring Tuff has a narrow range of (delta) 87 Sr values that can be calculated from the (delta) 87 Sr values of the rock considering advection through and reaction with the overlying nonwelded tuffs of the PTn. This model can be extended to estimate the variation of (delta) 87 Sr in the pore water through time; this approximates the variation of (delta) 87 Sr measured in calcite fracture coatings. In samples of calcite where no silica can be dated by other methods, strontium isotope data may be the only method to determine ages. In addition, other Sr-bearing minerals in the calcite and opal coatings, such as fluorite, may be dated using the same model

  1. An astronomical age for the Bishop Tuff and concordance with radioisotopic dates

    DEFF Research Database (Denmark)

    Rivera, Tiffany; Zeeden, Christian; Storey, Michael

    2014-01-01

    The Bishop Tuff forms a key stratigraphic horizon for synchronization of Quaternary sedimentary records in North America. The unit stratigraphically overlies the Matuyama-Brunhes geomagnetic polarity reversal by several thousand years; high-precision dating of this tuff may be valuable for regional...... and global correlation of records. The Quaternary time scale is anchored by 40Ar/39Ar ages on lava flows and ash layers where available, with stage boundaries and geomagnetic reversals including astronomically tuned records. However, astronomical dating has not yet validated the high-precision 238U/206Pb...... ages, including new single crystal 40Ar/39Ar sanidine fusion analyses presented here, which demonstrates that concordance through multiple dating techniques is achievable within the Quaternary...

  2. Sorption and desorption of remazol yellow by a Fe-zeolitic tuff

    Energy Technology Data Exchange (ETDEWEB)

    Solache R, M. J. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Villalva C, R.; Diaz N, M. C., E-mail: marcos.solache@inin.gob.m [Instituto Tecnologico de Toluca, Division de Estudios del Posgrado, Av. Tecnologico s/n, Ex-Rancho La Virgen, 52140 Metepec, Estado de Mexico (Mexico)

    2010-07-01

    The adsorption of remazol yellow from aqueous solution was evaluated using a Fe-zeolitic tuff. The adsorbent was characterized by scanning electron microscopy, IR spectroscopy and X-ray diffraction. Sorption kinetic and isotherms were determined and the adsorption behavior was analyzed. Kinetic pseudo-second order and Langmuir-Freundlich models were successfully applied to the experimental results, indicating chemisorption on a heterogeneous material. The regeneration of the material was best accomplished by using a H{sub 2}O{sub 2} solution. The sorption capacity of the Fe-zeolitic tuff increased when the saturated samples were treated with a H{sub 2O2} or FeCl{sub 3} solution. (Author)

  3. Fracture-lining minerals in the lower Topopah Spring Tuff at Yucca Mountain

    International Nuclear Information System (INIS)

    Carlos, B.A.; Bish, D.L.; Chipera, S.J.

    1991-01-01

    Fracture-lining minerals in the lower Topopah Spring Member of the Paintbrush Tuff at Yucca Mountain, Nevada, are being examined to characterize potential flow paths within and away from the candidate repository horizon. Fracture coatings within this interval can be divided into five categories based on rock matrix and type of fracture. Fracture coatings in the densely welded tuff above the basal vitrophyre, near the candidate repository horizon, include (1) those related to lithophysal cavities; (2) mordenite and manganese oxides on nearly planar fractures; (3) later fracture coatings consisting of zeolites, smectite, and calcite. Fracture-coating minerals in the vitrophyre are fine-grained and consist of smectite and a variety of zeolites. The non- to partially-welded vitric and/or zeolitic stuff below the vitrophyre contains fractures mostly lined by cristobalite and clinoptilolite. 13 refs., 2 figs., 1 tab

  4. Zircaloy cladding corrosion degradation in a Tuff repository: initial experimental plan

    International Nuclear Information System (INIS)

    Smith, H.D.

    1984-07-01

    The projected environmental history of a Tuff repository sited in an unsaturated hydrologic setting is evaluated to identify the potentially most severe corrosion conditions for Zircaloy spent fuel cladding. Three distinct corrosion periods are identified over the projected history. In two of those, liquid water may be present which is believed to produce the most severe corrosive environment for Zircaloy spent fuel cladding. In the time interval 100 to 1000 years after emplacement in the repository, the most severe condition is exposure to 170 0 C water at about 100 psi in an unbreached canister. This condition will be reproduced experimentally in an autoclave. For times after 1000 years, the most severe condition is exposure to 90 0 C water that is equilibrated with the tuff and invades breached canisters. This condition will be reproduced with a water bath system

  5. Studies of the mobility of uranium and thorium in Nevada Test Site tuff

    Energy Technology Data Exchange (ETDEWEB)

    Wollenberg, H.A.; Flexser, S.; Smith, A.R. [Lawrence Berkeley Lab., CA (United States)

    1991-06-01

    Hydro-geochemical processes must be understood if the movement of radionuclides away from a breached radioactive waste canister is to be modeled and predicted. In this respect, occurrences of uranium and thorium in hydrothermal systems are under investigation in tuff and in rhyolitic tuff that was heated to simulate the effects of introduction of radioactive waste. In these studies, high-resolution gamma spectrometry and fission-track radiography are coupled with observations of alteration mineralogy and thermal history to deduce the evidence of, or potential for movement of, U and Th in response to the thermal environment. Observations to date suggest that U was mobile in the vicinity of the heater but that localized reducing environments provided by Fe-Ti-Mn-oxide minerals concentrated U and thus attenuated its migration.

  6. Microautoradiography in studies of Pu(V) sorption by trace and fracture minerals in tuff

    International Nuclear Information System (INIS)

    Vaniman, D.; Furlano, A.; Chipera, S.; Thompson, J.; Triay, I.

    1996-01-01

    Microautoradiography was used to evaluate the mineralogic basis of Pu(V) retention by tuffs from Yucca Mountain, Nevada. Altered orthopyroxenes and oxide minerals are associated with high Pu retention but are limited to specific stratigraphic horizons. A weaker but more general association of Pu with smectite occurs in most samples. Thin-sections that cross fractures allow comparative studies of Pu retention by fracture-lining versus matrix minerals. Using Ag metal in emulsions as a measure of underlying Pu concentration, electron-microprobe analysis can quantify Pu retention along fracture walls and provide mineral/mineral Pu retention factors. For smectite-lined microfractures in zeolitized tuff, the smectite/clinoptilolite Pu retention factor is >80

  7. Safety Evaluation for Packaging (onsite) T Plant Canyon Items

    International Nuclear Information System (INIS)

    OBRIEN, J.H.

    2000-01-01

    This safety evaluation for packaging (SEP) evaluates and documents the ability to safely ship mostly unique inventories of miscellaneous T Plant canyon waste items (T-P Items) encountered during the canyon deck clean off campaign. In addition, this SEP addresses contaminated items and material that may be shipped in a strong tight package (STP). The shipments meet the criteria for onsite shipments as specified by Fluor Hanford in HNF-PRO-154, Responsibilities and Procedures for all Hazardous Material Shipments

  8. Diablo Canyon plant information management system and integrated communication system

    International Nuclear Information System (INIS)

    Stanley, J.W.; Groff, C.

    1990-01-01

    The implementation of a comprehensive maintenance system called the plant information management system (PIMS) at the Diablo Canyon plant, together with its associated integrated communication system (ICS), is widely regarded as the most comprehensive undertaking of its kind in the nuclear industry. This paper provides an overview of the program at Diablo Canyon, an evaluation of system benefits, and highlights the future course of PIMS

  9. Diablo Canyon plant information management system and integrated communication system

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, J.W.; Groff, C.

    1990-06-01

    The implementation of a comprehensive maintenance system called the plant information management system (PIMS) at the Diablo Canyon plant, together with its associated integrated communication system (ICS), is widely regarded as the most comprehensive undertaking of its kind in the nuclear industry. This paper provides an overview of the program at Diablo Canyon, an evaluation of system benefits, and highlights the future course of PIMS.

  10. Safety Evaluation for Packaging (onsite) T Plant Canyon Items

    Energy Technology Data Exchange (ETDEWEB)

    OBRIEN, J.H.

    2000-07-14

    This safety evaluation for packaging (SEP) evaluates and documents the ability to safely ship mostly unique inventories of miscellaneous T Plant canyon waste items (T-P Items) encountered during the canyon deck clean off campaign. In addition, this SEP addresses contaminated items and material that may be shipped in a strong tight package (STP). The shipments meet the criteria for onsite shipments as specified by Fluor Hanford in HNF-PRO-154, Responsibilities and Procedures for all Hazardous Material Shipments.

  11. B-Plant Canyon Ventilation Control System Description; FINAL

    International Nuclear Information System (INIS)

    MCDANIEL, K.S.

    1999-01-01

    Project W-059 installed a new B Plant Canyon Ventilation System. Monitoring and control of the system is implemented by the Canyon Ventilation Control System (CVCS). This document describes the CVCS system components which include a Programmable Logic Controller (PLC) coupled with an Operator Interface Unit (OIU) and application software. This document also includes an Alarm Index specifying the setpoints and technical basis for system analog and digital alarms

  12. Preliminary design and definition of field experiments for welded tuff rock mechanics program

    International Nuclear Information System (INIS)

    Zimmerman, R.M.

    1982-06-01

    The preliminary design contains objectives, typical experiment layouts, definitions of equipment and instrumentation, test matrices, preliminary design predictive modeling results for five experiments, and a definition of the G-Tunnel Underground Facility (GTUF) at the Nevada Test Site where the experiments are to be located. Experiments described for investigations in welded tuff are the Small Diameter Heater, Unit Cell-Canister Scale, Heated Block, Rocha Slot, and Miniature Heater

  13. Bench-scale experimental determination of the thermal diffusivity of crushed tuff

    International Nuclear Information System (INIS)

    Ryder, E.E.; Finley, R.E.; George, J.T.; Ho, C.K.; Longenbaugh, R.S.; Connolly, J.R.

    1996-06-01

    A bench-scale experiment was designed and constructed to determine the effective thermal diffusivity of crushed tuff. Crushed tuff particles ranging from 12.5 mm to 37.5 mm (0.5 in. to 1.5 in.) were used to fill a cylindrical volume of 1.58 m 3 at an effective porosity of 0.48. Two iterations of the experiment were completed; the first spanning approximately 502 hours and the second 237 hours. Temperatures near the axial heater reached 700 degrees C, with a significant volume of the test bed exceeding 100 degrees C. Three post-test analysis techniques were used to estimate the thermal diffusivity of the crushed tuff. The first approach used nonlinear parameter estimation linked to a one dimensional radial conduction model to estimate thermal diffusivity from the first 6 hours of test data. The second method used the multiphase TOUGH2 code in conjunction with the first 20 hours of test data not only to estimate the crushed tuffs thermal diffusivity, but also to explore convective behavior within the test bed. Finally, the nonlinear conduction code COYOTE-II was used to determine thermal properties based on 111 hours of cool-down data. The post-test thermal diffusivity estimates of 5.0 x 10-7 m 2 /s to 6.6 x 10-7 m 2 /s were converted to effective thermal conductivities and compared to estimates obtained from published porosity-based relationships. No obvious match between the experimental data and published relationships was found to exist; however, additional data for other particle sizes and porosities are needed

  14. Removal of ammonia from waste air streams with clinoptilolite tuff in its natural and treated forms

    Czech Academy of Sciences Publication Activity Database

    Ciahotný, K.; Melenová, L.; Jirglová, H.; Prokopová, Olga; Kočiřík, Milan; Eić, M.

    2006-01-01

    Roč. 12, č. 3 (2006), s. 219-226 ISSN 0929-5607 R&D Projects: GA ČR GA104/00/1007; GA ČR GP104/03/D183 Institutional research plan: CEZ:AV0Z40400503 Keywords : clinoptilolite tuffs * ammonia * adsorption * impregnation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.590, year: 2006

  15. Development of the data base for tuffs at Yucca Mountain, Nevada Test Site

    International Nuclear Information System (INIS)

    Lappin, A.R.

    1981-11-01

    The purposes of the data-base development described here are: (1) to provide sufficient input for the modeling and analysis required to support a horizon-selection decision in December, 1982; and (2) to support follow-on detailed horizon evaluation. Initial data collection must, therefore, be complete by August, 1982. Data will include; (1) thermal conductivity; (2) thermal expansion; (3) matrix and fracture mechanical properties; (4) bulk properties; and (5) functional thermomechanical stratigraphy of the tuffs at Yucca Mountain

  16. Is Canyon Width a Diagnostic Indicator of the Discharge of Megafloods on Earth and Mars?

    Science.gov (United States)

    Lapotre, M. G.; Lamb, M. P.

    2013-12-01

    On Earth, large floods have carved steep-walled and amphitheater-headed canyons from the Pleistocene (e.g. Box Canyon, ID) through the Holocene (e.g. Asbyrgi Canyon, Iceland), to historic times (e.g. Canyon Lake Gorge, TX). The geologic record on Mars suggests that similar floods have carved canyons by waterfall retreat about 3.5 billion years ago, when the red planet was wetter and possibly warmer. We currently lack robust paleo-hydraulic tools to reconstruct the discharge of ancient floods, especially on Mars where sediment sizes are obscured from observation. To address this issue, we hypothesize that the width of canyon escarpment is controlled by the hydraulics of the canyon-carving flood due to focusing of the flood into the canyon head. We compiled field data from multiple canyons and floods on Earth and Mars and show that there is a correlation between estimated flood discharge and canyon headwall width. To explore what sets this relationship, we identified five important parameters using dimensional analysis: the Froude number, the ratio of backwater length to canyon length, the ratio of backwater length to flood width, the ratio of canyon width to flood width, and the topographic slope upstream of the canyon. We used the hydraulic numerical modeling suite ANUGA to simulate overland flow over different canyon geometries and flood parameters to systematically explore the relative bed shear stresses along the canyon rim as a metric for flow focusing. Results show that canyons that exceed a certain length, scaling with the hydraulic backwater length, have shear stresses at their heads that are significantly higher than near the canyon mouth. Shear stresses along the rim of the canyon sidewalls are limited, in comparison to stresses along the canyon head, when the flood width is of the order of the backwater length. Flow focusing only occurs for subcritical flow. Together, these results suggest that canyons may only grow from a perturbation that is large

  17. [Effect of greenbelt on pollutant dispersion in street canyon].

    Science.gov (United States)

    Xu, Wei-Jia; Xing, Hong; Yu, Zhi

    2012-02-01

    The effect feature of greenbelt on flow field and pollutant dispersion in urban street canyon was researched. The greenbelt was assumed as uniform porous media and its aerodynamics property defined by the pressure loss coefficient. Subsequently, the pollutant dispersion in the street canyon of which there was greenbelt in the middle was simulated with the steady-state standard kappa-epsilon turbulence model and species transport equation. The simulated results agreed well with the wind-tunnel data. Compared with the treeless case, it finds that the street canyon contain a clockwise vortex, the pollutant concentration of the leeward was several times than the windward and the growth rate of pollutant concentration was 46.0%. The further simulation for the impact of tree crown position on the airflow and pollutant dispersion finds that the height of major vortex center in the street canyon increases with the height of tree crown and gradually closes the top of windward building This causes that the average wind speed in the street canyon decreases. Especially when the top of tree crown over the roof and hinder the air flow above the street canyon, the average pollutant concentration increases with the height of tree crown rapidly.

  18. Studies of ancient concrete as analogs of cementitious sealing materials for a repository in tuff

    Energy Technology Data Exchange (ETDEWEB)

    Roy, D.M.; Langton, C.A.

    1989-03-01

    The durability of ancient cementitious materials has been investigated to provide data applicable to determining the resistance to weathering of concrete materials for sealing a repository for storage of high-level radioactive waste. Because tuff and volcanic ash are used in the concretes in the vicinity of Rome, the results are especially applicable to a waste repository in tuff. Ancient mortars, plasters, and concretes collected from Rome, Ostia, and Cosa dating to the third century BC show remarkable durability. The aggregates used in the mortars, plasters, and concretes included basic volcanic and pyroclastic rocks (including tuff), terra-cotta, carbonates, sands, and volcanic ash. The matrices of ancient cementitious materials have been characterized and classified into four categories: (1) hydraulic hydrated lime and hydrated lime cements, (2) hydraulic aluminous and ferruginous hydrated lime cements ({plus_minus} siliceous components), (3) pozzolana/hydrated lime cements, and (4) gypsum cements. Most of the materials investigated are in category (3). The materials were characterized to elucidate aspects of the technology that produced them and their response to the environmental exposure throughout their centuries of existence. Their remarkable properties are the result of a combination of chemical, mineralogical, and microstructural factors. Their durability was found to be affected by the matrix mineralogy, particle size, and porosity; aggregate type, grading and proportioning; and the methodology of placement. 30 refs.

  19. Creep in Topopah Spring Member welded tuff. Yucca Mountain Site Characterization Project

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.J. III; Boyd, P.J.; Noel, J.S. [New England Research, Inc., White River Junction, VT (United States); Price, R.H. [Sandia National Labs., Albuquerque, NM (United States)

    1995-06-01

    A laboratory investigation has been carried out to determine the effects of elevated temperature and stress on the creep deformation of welded tuffs recovered from Busted Butte in the vicinity of Yucca Mountain, Nevada. Water saturated specimens of tuff from thermal/mechanical unit TSw2 were tested in creep at a confining pressure of 5.0 MPa, a pore pressure of 4.5 MPa, and temperatures of 25 and 250 C. At each stress level the load was held constant for a minimum of 2.5 {times} 10{sup 5} seconds and for as long as 1.8 {times} 10{sup 6} seconds. One specimen was tested at a single stress of 80 MPa and a temperature of 250 C. The sample failed after a short time. Subsequent experiments were initiated with an initial differential stress of 50 or 60 MPa; the stress was then increased in 10 MPa increments until failure. The data showed that creep deformation occurred in the form of time-dependent axial and radial strains, particularly beyond 90% of the unconfined, quasi-static fracture strength. There was little dilatancy associated with the deformation of the welded tuff at stresses below 90% of the fracture strength. Insufficient data have been collected in this preliminary study to determine the relationship between temperature, stress, creep deformation to failure, and total failure time at a fixed creep stress.

  20. Creep in Topopah Spring Member welded tuff. Yucca Mountain Site Characterization Project

    International Nuclear Information System (INIS)

    Martin, R.J. III; Boyd, P.J.; Noel, J.S.; Price, R.H.

    1995-06-01

    A laboratory investigation has been carried out to determine the effects of elevated temperature and stress on the creep deformation of welded tuffs recovered from Busted Butte in the vicinity of Yucca Mountain, Nevada. Water saturated specimens of tuff from thermal/mechanical unit TSw2 were tested in creep at a confining pressure of 5.0 MPa, a pore pressure of 4.5 MPa, and temperatures of 25 and 250 C. At each stress level the load was held constant for a minimum of 2.5 x 10 5 seconds and for as long as 1.8 x 10 6 seconds. One specimen was tested at a single stress of 80 MPa and a temperature of 250 C. The sample failed after a short time. Subsequent experiments were initiated with an initial differential stress of 50 or 60 MPa; the stress was then increased in 10 MPa increments until failure. The data showed that creep deformation occurred in the form of time-dependent axial and radial strains, particularly beyond 90% of the unconfined, quasi-static fracture strength. There was little dilatancy associated with the deformation of the welded tuff at stresses below 90% of the fracture strength. Insufficient data have been collected in this preliminary study to determine the relationship between temperature, stress, creep deformation to failure, and total failure time at a fixed creep stress

  1. Estimates of spatial correlation in volcanic tuff, Yucca Mountain, Nevada: Yucca Mountain Site Characterization Project

    International Nuclear Information System (INIS)

    Rautman, C.A.

    1991-02-01

    The spatial correlation structure of volcanic tuffs at and near the site of the proposed high-level nuclear waste repository at Yucca Mountain, Nevada, is estimated using samples obtained from surface outcrops and drill holes. Data are examined for four rock properties: porosity, air permeability, saturated hydraulic conductivity, and dry bulk density. Spatial continuity patterns are identified in both lateral and vertical (stratigraphic) dimensions. The data are examined for the Calico Hills tuff stratigraphic unit and also without regard for stratigraphy. Variogram models fitted to the sample data from the tuffs of Calico Hills indicate that porosity is correlated laterally over distances of up to 3000 feet. If air permeability and saturated conductivity values are viewed as semi-interchangeable for purposes of identifying spatial structure, the data suggest a maximum range of correlation of 300 to 500 feet without any obvious horizontal to vertical anisotropy. Continuity exists over vertical distances of roughly 200 feet. Similar variogram models fitted to sample data taken from vertical drill holes without regard for stratigraphy suggest that correlation exists over distances of 500 to 800 feet for each rock property examined. Spatial correlation of rock properties violates the sample-independence assumptions of classical statistics to a degree not usually acknowledged. In effect, the existence of spatial structure reduces the ''equivalent'' number of samples below the number of physical samples. This reduction in the effective sampling density has important implications for site characterization for the Yucca Mountain Project. 19 refs., 43 figs., 5 tabs

  2. A performance assessment methodology for high-level radioactive waste disposal in unsaturated, fractured tuff

    International Nuclear Information System (INIS)

    Gallegos, D.P.

    1991-07-01

    Sandia National Laboratories, has developed a methodology for performance assessment of deep geologic disposal of high-level nuclear waste. The applicability of this performance assessment methodology has been demonstrated for disposal in bedded salt and basalt; it has since been modified for assessment of repositories in unsaturated, fractured tuff. Changes to the methodology are primarily in the form of new or modified ground water flow and radionuclide transport codes. A new computer code, DCM3D, has been developed to model three-dimensional ground-water flow in unsaturated, fractured rock using a dual-continuum approach. The NEFTRAN 2 code has been developed to efficiently model radionuclide transport in time-dependent velocity fields, has the ability to use externally calculated pore velocities and saturations, and includes the effect of saturation dependent retardation factors. In order to use these codes together in performance-assessment-type analyses, code-coupler programs were developed to translate DCM3D output into NEFTRAN 2 input. Other portions of the performance assessment methodology were evaluated as part of modifying the methodology for tuff. The scenario methodology developed under the bedded salt program has been applied to tuff. An investigation of the applicability of uncertainty and sensitivity analysis techniques to non-linear models indicate that Monte Carlo simulation remains the most robust technique for these analyses. No changes have been recommended for the dose and health effects models, nor the biosphere transport models. 52 refs., 1 fig

  3. Effects of canyon geometry on the distribution of traffic-related air pollution in a large urban area: Implications of a multi-canyon air pollution dispersion model

    Science.gov (United States)

    Fu, Xiangwen; Liu, Junfeng; Ban-Weiss, George A.; Zhang, Jiachen; Huang, Xin; Ouyang, Bin; Popoola, Olalekan; Tao, Shu

    2017-09-01

    Street canyons are ubiquitous in urban areas. Traffic-related air pollutants in street canyons can adversely affect human health. In this study, an urban-scale traffic pollution dispersion model is developed considering street distribution, canyon geometry, background meteorology, traffic assignment, traffic emissions and air pollutant dispersion. In the model, vehicle exhausts generated from traffic flows first disperse inside street canyons along the micro-scale wind field generated by computational fluid dynamics (CFD) model. Then, pollutants leave the street canyon and further disperse over the urban area. On the basis of this model, the effects of canyon geometry on the distribution of NOx and CO from traffic emissions were studied over the center of Beijing. We found that an increase in building height leads to heavier pollution inside canyons and lower pollution outside canyons at pedestrian level, resulting in higher domain-averaged concentrations over the area. In addition, canyons with highly even or highly uneven building heights on each side of the street tend to lower the urban-scale air pollution concentrations at pedestrian level. Further, increasing street widths tends to lead to lower pollutant concentrations by reducing emissions and enhancing ventilation simultaneously. Our results indicate that canyon geometry strongly influences human exposure to traffic pollutants in the populated urban area. Carefully planning street layout and canyon geometry while considering traffic demand as well as local weather patterns may significantly reduce inhalation of unhealthy air by urban residents.

  4. Davis Canyon noise analysis: Revision 2

    International Nuclear Information System (INIS)

    1985-11-01

    A study was performed as part of the Civilian Radioactive Waste Management Program to quantify the level and effect of noise from the various major phases of development of the proposed potentially acceptable nuclear waste repository site at Davis Canyon, Utah. This report contains the results of a predictive noise level study for the site characterization, repository construction, and repository operational phases. Included herein are graphic representations of energy averaged sound levels, and of audibility levels representing impact zones expected during each phase. Sound levels from onsite and offsite activity including traffic on highways and railroad routes are presented in isopleth maps. A description of the Environmental Noise Prediction Model used for the study, the study basis and methodologies, and actual modeling data are provided. Noise and vibration levels from blasting are also predicted and evaluated. Protective noise criteria containing a margin of safety are used in relation to residences, schools, churches, noise-sensitive recreation areas, and noise-sensitive biological resources. Protective ground motion criteria for ruins and delicate rock formation in Canyonlands National Park and for human annoyance are used in the evaluation of blasting. The evaluations provide the basis for assessing the noise impacts from the related activities at the proposed repository. 45 refs., 21 figs., 15 tabs

  5. Geology of the Nine Canyon Map Area

    International Nuclear Information System (INIS)

    Jones, M.G.; Landon, R.D.

    1978-09-01

    The basalt stratigraphy and structure of a 175-square kilometer area (the Nine Canyon Map Area) along the southern margin of the Pasco Basin have been studied to help assess the feasibility of a nuclear waste terminal storage facility. Detailed mapping shows that uplift of the Horse Heaven Hills began prior to extrusion of the Priest Rapids Member of the Wanapum Basalt, Columbia River Basalt Group. Both the Pomoma and the Elephant Mountain members (Saddle Mountains Basalt, Columbia River Basalt Group) are wide-spread throughout the basin, but thin considerably along the Horse Heaven Hills in the vicinity of Wallula Gap. The Ice Harbor Member is present only along the northern margin of the map area and possibly occupies a paleo-channel. The Rattlesnake Hills-Wallula Gap Lineament trends north 60 degrees west and intersects the older Horse Heaven Hills anticline in Wallula Gap. Four faults of short length and small vertical displacement are located along this structure. Within the map area, the intensity of folding increases, and the style of faulting changes from normal to reverse with proximity to the Wallula Gap area. No evidence for Quaternary deformation was found

  6. The international INTRAVAL project. Phase 2, working group 1 report. Flow and tracer experiments in unsaturated tuff and soil. Las Cruces trench and Apache Leap tuff studies

    International Nuclear Information System (INIS)

    Nicholson, T.J.; Guzman-Guzman, A.; Hills, R.; Rasmussen, T.C.

    1997-01-01

    The Working Group 1 final report summaries two test case studies, the Las Cruces Trench (LCT), and Apache Leap Tuff Site (ALTS) experiments. The objectives of these two field studies were to evaluate models for water flow and contaminant transport in unsaturated, heterogeneous soils and fractured tuff. The LCT experiments were specifically designed to test various deterministic and stochastic models of water flow and solute transport in heterogeneous, unsaturated soils. Experimental data from the first tow LCT experiments, and detailed field characterisation studies provided information for developing and calibrating the models. Experimental results from the third experiment were held confidential from the modellers, and were used for model comparison. Comparative analyses included: point comparisons of water content; predicted mean behavior for water flow; point comparisons of solute concentrations; and predicted mean behavior for tritium transport. These analyses indicated that no model, whether uniform or heterogeneous, proved superior. Since the INTRAVAL study, however, a new method has been developed for conditioning the hydraulic properties used for flow and transport modelling based on the initial field-measured water content distributions and a set of scale-mean hydraulic parameters. Very good matches between the observed and simulated flow and transport behavior were obtained using the conditioning procedure, without model calibration. The ALTS experiments were designed to evaluate characterisation methods and their associated conceptual models for coupled matrix-fracture continua over a range of scales (i.e., 2.5 centimeter rock samples; 10 centimeter cores; 1 meter block; and 30 meter boreholes). Within these spatial scales, laboratory and field tests were conducted for estimating pneumatic, thermal, hydraulic, and transport property values for different conceptual models. The analyses included testing of current conceptual, mathematical and physical

  7. 2013 Pacific Gas and Electric Diablo Canyon Power Plant (DCPP): San Simeon, CA Central Coast

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Diablo Canyon Power Plant (DCPP) LiDAR and Imagery datasets are comprised of three separate LiDAR surveys: Diablo Canyon (2010), Los Osos (2011), and San Simeon...

  8. 2011 Pacific Gas and Electric Diablo Canyon Power Plant (DCPP): Los Osos, CA Central Coast

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Diablo Canyon Power Plant (DCPP) LiDAR and Imagery datasets are comprised of three separate LiDAR surveys: Diablo Canyon (2010), Los Osos (2011), and San Simeon...

  9. On the escape of pollutants from urban street canyons

    Energy Technology Data Exchange (ETDEWEB)

    Baik, J.J.; Kim, J.J. [Kwangju Inst. of Science and Technology (Korea). Dept. of Environmental Science and Engineering

    2002-07-01

    Pollutant transport from urban street canyons is numerically investigated using a two-dimensional flow and dispersion model. The ambient wind blows perpendicular to the street and passive pollutants are released at the street level. Results from the control experiment with a street aspect ratio of 1 show that at the roof level of the street canyon, the vertical turbulent flux of pollutants is upward everywhere and the vertical flux of pollutants by mean flow is upward or downward. The horizontally integrated vertical flux of pollutants by mean flow at the roof level of the street canyon is downward and its magnitude is much smaller than that by turbulent process. These results indicate that pollutants escape from the street canyon mainly by turbulent process and that the net effect of mean flow is to make some escaped pollutants reenter the street canyon. Further experiments with different inflow turbulence intensities, inflow wind speeds, and street aspect ratio confirm the findings from the control experiment. In the case of two isolated buildings, the horizontally integrated vertical flux of pollutants by mean flow is upward due to flow separation but the other main results are the same as those from the control experiment. (author)

  10. Cold-water coral ecosystems in Cassidaigne Canyon: An assessment of their environmental living conditions

    OpenAIRE

    Fabri, Marie-claire; Bargain, Annaelle; Pairaud, Ivane; Pedel, Laura; Taupier-letage, I.

    2017-01-01

    The Cassidaigne canyon is one of the two canyons (together with Lacaze-Duthiers) of the French Mediterranean coast in which cold-water corals have settled and formed large colonies, providing a structural habitat for other species. Nevertheless, the communities settled in the Cassidaigne canyon are physically impacted by discharges of bauxite residues. New information on the distribution of the species Madrepora oculata and the associated species diversity in Cassidaigne canyon was provid...

  11. CODASC : a database for the validation of street canyon dispersion models

    OpenAIRE

    Gromke, C.B.

    2013-01-01

    CODASC stands for Concentration Data of Street Canyons (CODASC 2008, www.codasc.de). It is a database which provides traffic pollutant concentrations in urban street canyons obtained from wind-tunnel dispersion experiments. CODASC comprises concentration data of street canyons with different aspect ratios subjected to various wind directions and also for street canyons with tree-avenues. The database includes concentration data of tree-avenue configurations of different tree arrangement, tree...

  12. Consideration of Nuclear Criticality When Directly Disposing Highly Enriched Spent Nuclear Fuel in Unsaturated Tuff - I: Nuclear Criticality Constraints

    International Nuclear Information System (INIS)

    Rechard, Rob P.; Sanchez, Lawrence C.; Trellue, Holly R.

    2003-01-01

    This paper presents the mass, concentration, and volume required for a critical event to occur in homogeneous mixtures of fissile material and various other geologic materials. The fissile material considered is primarily highly enriched uranium spent fuel; however, 239 Pu is considered in some cases. The non-fissile materials examined are those found in the proposed repository area at Yucca Mountain, Nevada: volcanic tuff, iron rust, concrete, and naturally occurring water. For 235 U, the minimum critical solid concentration for tuff was 5 kg/m 3 (similar to sandstone), and in goethite, 45 kg/m 3 . The critical mass of uranium was sensitive to a number of factors, such as moisture content and fissile enrichment, but had a minimum, assuming almost 100% saturation and >20% enrichment, of 18 kg in tuff as Soddyite (or 9.5 kg as UO 2 ) and 7 kg in goethite. For 239 Pu, the minimum critical solid concentration for tuff was 3 kg/m 3 (similar to sandstone); in goethite, 20 kg/m 3 . The critical mass of plutonium was also sensitive to a number of factors, but had a minimum, assuming 100% saturation and 80-90% enrichment, of 5 kg in tuff and 6 kg in goethite

  13. Radionuclide transfer onto ground surface in surface water flow. 2. Undisturbed tuff rock

    International Nuclear Information System (INIS)

    Mukai, Masayuki; Takebe, Shinichi; Komiya, Tomokazu

    1994-09-01

    Radionuclide migration with ground surface water flow is considered to be one of path ways in the scenario for environmental migration of the radionuclide leaked from LLRW depository. To study the radionuclide migration demonstratively, a ground surface radionuclide migration test was carried out by simulating radioactive solution flowing on the sloped tuff rock surface. Tuff rock sample of 240 cm in length taken from the Shimokita district was used to test the transfer of 60 Co, 85 Sr and 137 Cs onto the sample surface from the flowing radioactive solution under restricted infiltration condition at flow rates of 25, 80, 160ml/min and duration of 56h. The concentration change of the radionuclides in effluent was nearly constant as a function of elapsed time during the experimental period, but decreased with lower flow rates. Among the three radionuclides, 137 Cs was greatly decreased its concentration to 30% of the inflow. Adsorbed distribution of the radionuclides concentration on the ground surface decreased gradually with the distance from the inlet, and showed greater gradient at lower flow rate. Analyzing the result by the migration model, where a vertical advection distribution and two-dimensional diffusion in surface water are adopted with a first order adsorption reaction, value of migration parameters was obtained relating to the radionuclide adsorption and the surface water flow, and the measured distribution could be well simulated by adopting the value to the model. By comparing the values with the case of loamy soil layer, all values of the migration parameters showed not so great difference between two samples for 60 Co and 85 Sr. For 137 Cs, reflecting a few larger value of adsorption to the tuff rock, larger ability to reduce the concentration of flowing radioactive solution could be indicated than that to the loamy soil surface by estimation for long flowed distance. (author)

  14. Estimation of possibilities of making euro pallets from reclaimed polyolefin’s with tuff

    Directory of Open Access Journals (Sweden)

    S. Kuciel

    2010-07-01

    Full Text Available Possibilities of reusing and developing of waste plastics are one of the main problems of waste management for municipal governmentespecially in the context of adapting Polish law to standards of EC [1]. During the last 10 years total amount of plastics waste increasedtwice, especially in communal agglomerations. Among communal waste plastics make up 7 to 14% of whole their mass and 30% of theirvolume [1,2]. Plastic products have been recycled to be used in a number of different products often different from their original use.Reclaimed plastics can’t be used as products which have contact with food or as high demands esthetic and hygienic products, they alsoshouldn’t be applied as short-time used products because they quickly come back to plastics store-place. Reclaimed plastics have lowerproperties than virgin plastics – mainly the strength falls with the simultaneous fall of modules and increase fragile especially for PP, PE,PS and PET [1]. One of the possibilities of reinforcement of polyolefines is adding diverse fillers like glass or carbon fibers (but they arerather expensive and natural fillers like mineral, wood and others [3]. It’s especially important for wasted of low density polyethylenewhich has low modulus. For the tests it was used waste polyethylene (LDPE and HDPE from industrial with 15% mineral fillers – tuff.For the tests it was prepared two kinds of composites materials with 15% of tuff powder. Besides for comparison it was tested recycledpolyethylene (HDPE and LDPE and next was tested specimens cut out from produced europallets (with 15% of tuff. It was testedmechanical properties all prepared composite materials like tensile strength, stress and bending e-modulus and processing properties likemelt flow, Vicat point and photos on SEM microscope.

  15. Influence of the Nazaré Canyon, central Portuguese margin, on late winter coccolithophore assemblages

    NARCIS (Netherlands)

    Guerreiro, C.; Sá, C.; de Stigter, H.; Oliveira, A.; Cachão, M.; Cros, L.; Borges, C.; Quaresma, L.; Santos, A.I.; Fortuño, J.-M.; Rodrigez, A.

    2014-01-01

    This paper presents a first attempt to characterize coccolithophore assemblages occurring in the context of an active submarine canyon. Coccolithophores from the upper-middle sections of the Nazaré Canyon (central Portuguese margin) – one of the largest canyons of the European continental margin –

  16. The urban canyon and building energy use: Urban density versus daylight and passive solar gains

    DEFF Research Database (Denmark)

    Strømann-Andersen, Jakob Bjørn; Sattrup, Peter Andreas

    2011-01-01

    .It was found that the geometry of urban canyons has an impact on total energy consumption in the range of up to +30% for offices and +19% for housing, which shows that the geometry of urban canyons is a key factor in energy use in buildings. It was demonstrated how the reflectivity of urban canyons plays...

  17. 77 FR 8895 - Jimbilnan, Pinto Valley, Black Canyon, Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and...

    Science.gov (United States)

    2012-02-15

    ..., Pinto Valley, Black Canyon, Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and Bridge Canyon..., Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and Bridge Canyon Wilderness Areas, Lake Mead... wilderness character; providing for reasonable use of Spirit Mountain and adjacent areas in a manner meeting...

  18. CODASC : a database for the validation of street canyon dispersion models

    NARCIS (Netherlands)

    Gromke, C.B.

    2013-01-01

    CODASC stands for Concentration Data of Street Canyons (CODASC 2008, www.codasc.de). It is a database which provides traffic pollutant concentrations in urban street canyons obtained from wind-tunnel dispersion experiments. CODASC comprises concentration data of street canyons with different aspect

  19. Trees in urban street canyons and their impact on the dispersion of automobile exhausts

    NARCIS (Netherlands)

    Gromke, C.B.; Ruck, B.

    2007-01-01

    The aim of the present study is to clarify the influence of trees on the dispersion of automobile exhausts in urban street canyons. For this purpose, measurements have been performed with a small scale wind tunnel model of an idealized, isolated street canyon with model trees placed along the canyon

  20. 33 CFR 165.1171 - Copper Canyon, Lake Havasu, Colorado River-Regulated Navigation Area.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Copper Canyon, Lake Havasu... Guard District § 165.1171 Copper Canyon, Lake Havasu, Colorado River—Regulated Navigation Area. (a) Location. The following is a regulated navigation area: (1) In the water area of Copper Canyon, Lake Havasu...

  1. Standardized methods for Grand Canyon fisheries research 2015

    Science.gov (United States)

    Persons, William R.; Ward, David L.; Avery, Luke A.

    2013-01-01

    This document presents protocols and guidelines to persons sampling fishes in the Grand Canyon, to help ensure consistency in fish handling, fish tagging, and data collection among different projects and organizations. Most such research and monitoring projects are conducted under the general umbrella of the Glen Canyon Dam Adaptive Management Program and include studies by the U.S. Geological Survey (USGS), U.S. Fish and Wildlife Service (FWS), National Park Service (NPS), the Arizona Game and Fish Department (AGFD), various universities, and private contractors. This document is intended to provide guidance to fieldworkers regarding protocols that may vary from year to year depending on specific projects and objectives. We also provide herein documentation of standard methods used in the Grand Canyon that can be cited in scientific publications, as well as a summary of changes in protocols since the document was first created in 2002.

  2. Thermal effects on water exclusion from a cavity in unsaturated tuff

    International Nuclear Information System (INIS)

    Zhou, W.; Chambre, P.L.; Pigford, T.H.; Lee, W.W.L.

    1992-01-01

    For an unsaturated, fractured porous medium subjected to uniform infiltration, we analyze thermal effects on water exclusion from cavities. This is of practical interest in a nuclear waste repository. A crucial question is: How much infiltration will lead to heated cavity-rock interface in tunnels and drifts being saturated so that water can enter a cavity. The combination of cavity size, dimensionless temperature difference, and infiltration rate that will lead to the critical condition at the cavity apex; this calculation considers the tuff matrix only. Here, the large projection area of the cavity intercepts large amounts of infiltration, requiring a lesser critical infiltration rate to saturate the cavity apex

  3. Criticality characteristics of mixtures of plutonium, silicon dioxide, Nevada tuff, and water

    International Nuclear Information System (INIS)

    Sanchez, R.; Myers, W.; Hayes, D.

    1997-01-01

    The nuclear criticality characteristics of mixtures of plutonium, silicon dioxide, and water (Part A) or plutonium, silicon dioxide, Nevada Yucca Mountain tuff, and water (Part B) have become of interest because of the appearance of recent papers on the subject. These papers postulate that if excess weapons plutonium is vitrified into a silicate log and buried underground, a self-sustaining neutron chain reaction may develop given sufficient time and interaction with the burial medium. Moreover, given specific geologic actions resulting in postulated configurations, the referenced papers state that nuclear explosions could occur with multi-kiloton yields or yields equivalent to hundreds of tons of TNT

  4. Experimental Analyses of Yellow Tuff Spandrels of Post-medieval Buildings in the Naples Area

    International Nuclear Information System (INIS)

    Calderoni, B.; Cordasco, E. A.; Lenza, P.; Guerriero, L.

    2008-01-01

    Experimental analyses have been carried out on tuff masonry specimens in order to investigate the structural behaviour of historical buildings in the Naples area (Southern Italy). Spandrels of post-medieval buildings (late XVI to early XX century) have been analysed, with emphasis on morphological characteristics according to chronological indicators. Results of the experimentation on scaled models (1:10) are discussed and the better behaviour of historical masonry typologies on respect to the modern one is highlighted. Comparison with theoretical formulations of ultimate shear resistance are provided too

  5. Experimental research on sealing of boreholes, shafts and ramps in welded tuff

    International Nuclear Information System (INIS)

    Fuenkajorn, K.

    1996-01-01

    Laboratory and in-situ experiments have been conducted to determine the mechanical and hydraulic performance of cement borehole seals in densely welded Apache Leap tuff. Test results indicate that under saturated conditions, commercial expansive cement can provide good bond strength and adequate hydraulic performance for borehole seal under changing stress conditions. The cement seal should be installed at the intact portion of the opening, and should have a length-to-diameter ratio greater than four. Drying increases borehole plug permeability and decreases mechanical and hydraulic bonds at the plug-rock interface. In-situ testing indicates that installation procedure may significantly affect the cement plug performance

  6. Preliminary calculations of release rates from spent fuel in a tuff repository

    International Nuclear Information System (INIS)

    Apted, M.J.; O'Connell, W.J.; Lee, K.H.; MacIntyre, A.T.; Ueng, T.S.; Pigford, T.H.; Lee, W.W.L.

    1991-01-01

    Time-dependent release rates of Tc-99, I-129, Cs-135, and Np-237 have been calculated for wet-drip and moist-continuous release modes from the engineered barrier system of a potential nuclear waste repository in unsaturated tuff, representative of a possible repository at Yucca Mountain in southern Nevada. We describe the modes of water contact and of release of dissolved radionuclides to the surrounding intact rock, and the corresponding calculational models. We list the parameter values adopted, and then present numerical results, conclusions, and recommendations. 21 refs., 5 figs., 2 tabs

  7. Laboratory measurement of permeability upscaling: Results for the Topopah Spring Member of the Paintbrush Tuff

    International Nuclear Information System (INIS)

    Tidwell, V.C.; Wilson, J.L.

    1997-01-01

    Parameterization of predictive models is often complicated by the inability to make measurements at the same scale at which one wishes to perform the analysis. This disparity in scales necessitates the use of some averaging or upscaling model to compute the desired effective media properties. In efforts to better model permeability upscaling, laboratory experiments have been conducted on a series of rock samples with different genetic origins. These experiments involve the collection of exhaustive permeability data sets at different sample supports (i.e., sample volumes) using a specially designed minipermeameter test system. Here the authors present a synopsis of such a data set collected from a block of volcanic tuff

  8. Excavation effects on tuff - recent findings and plans for investigations at Yucca Mountain

    International Nuclear Information System (INIS)

    Blejwas, T.E.; Zimmerman, R.M.; Shephard, L.E.

    1989-01-01

    Plans for site-characterization testing and constructing an exploratory shaft facility (ESF) at Yucca Mountain, Nevada, have been influenced by the construction and monitoring of stable openings in G-Tunnel on the Nevada Test Site. G-Tunnel provides access for testing in a thin bed of unsaturated welded tuff that is similar to that at Yucca Mountain. The data from the experiments in the ESF will be used to validate analytical methods for predicting the response of underground openings to the excavation process and to the heat generated by the waste

  9. Corrosion performance of metals and alloys in a tuff geochemical environment

    International Nuclear Information System (INIS)

    Van Konynenburg, R.A.; McCright, R.D.

    1985-01-01

    Reference and alternate alloy systems have been chosen for use in fabricating waste packages for a potential high-level nuclear waste repository in tuff. The main corrosion concerns have been identified. Testing performed to date indicates that austenitic stainless steels woul perform well as package materials under the expected conditions as well as the less likely extreme conditions so far postulated. Carbon steel appears to be adequate as a material for borehole liners. Copper-based alloys and Zircaloys are also undergoing corrosion testing, the former as alternate package materials, and the latter because of their presence as spent fuel cladding. 17 references, 2 tables

  10. Parametric study of the effects of thermal environment on a waste package for a tuff repository

    Energy Technology Data Exchange (ETDEWEB)

    Johnstone, J K; Sundberg, W D; Krumhansl, J L [Sandia National Laboratories Albuquerque, NM, (USA)

    1982-12-31

    The thermal environment has been modeled in a simple reference waste package in a tuff repository for a variety of variables. The waste package was composed of the waste form, canister, overpack and backfill. The emplacement hole was 122cm dia. Waste forms used in the calculations were commercial high level waste (CHLW) and spent fuel (SF). Canister loadings varied from 50 to 100 kW/acre. Primary attention was focused on the backfill behavior in the thermal and chemical environment. Results are related to the maximum temperature calculated for the backfill. These calculations raise serious concerns about the effectiveness of the backfill within the context of the total waste package.

  11. Regional economic impacts of Grand Canyon river runners.

    Science.gov (United States)

    Hjerpe, Evan E; Kim, Yeon-Su

    2007-10-01

    Economic impact analysis (EIA) of outdoor recreation can provide critical social information concerning the utilization of natural resources. Outdoor recreation and other non-consumptive uses of resources are viewed as environmentally friendly alternatives to extractive-type industries. While outdoor recreation can be an appropriate use of resources, it generates both beneficial and adverse socioeconomic impacts on rural communities. The authors used EIA to assess the regional economic impacts of rafting in Grand Canyon National Park. The Grand Canyon region of northern Arizona represents a rural US economy that is highly dependent upon tourism and recreational expenditures. The purpose of this research is twofold. The first is to ascertain the previously unknown regional economic impacts of Grand Canyon river runners. The second purpose is to examine attributes of these economic impacts in terms of regional multipliers, leakage, and types of employment created. Most of the literature on economic impacts of outdoor recreation has focused strictly on the positive economic impacts, failing to illuminate the coinciding adverse and constraining economic impacts. Examining the attributes of economic impacts can highlight deficiencies and constraints that limit the economic benefits of recreation and tourism. Regional expenditure information was obtained by surveying non-commercial boaters and commercial outfitters. The authors used IMPLAN input-output modeling to assess direct, indirect, and induced effects of Grand Canyon river runners. Multipliers were calculated for output, employment, and income. Over 22,000 people rafted on the Colorado River through Grand Canyon National Park in 2001, resulting in an estimated $21,100,000 of regional expenditures to the greater Grand Canyon economy. However, over 50% of all rafting-related expenditures were not captured by the regional economy and many of the jobs created by the rafting industry are lower-wage and seasonal. Policy

  12. BLANCO MOUNTAIN AND BLACK CANYON ROADLESS AREAS, CALIFORNIA.

    Science.gov (United States)

    Diggles, Michael F.; Rains, Richard L.

    1984-01-01

    The mineral survey of the Blanco Mountain and Black Canyon Roadless Areas, California indicated that areas of probable and substantiated mineral-resource potential exist only in the Black Canyon Roadless Area. Gold with moderate amounts of lead, silver, zinc, and tungsten, occurs in vein deposits and in tactite. The nature of the geological terrain indicates little likelihood for the occurrence of energy resources in the roadless areas. Detailed geologic mapping might better define the extent of gold mineralization. Detailed stream-sediment sampling and analysis of heavy-mineral concentrations could better define tungsten resource potential.

  13. Are amphitheater headed canyons indicative of a particular formative process?

    Science.gov (United States)

    Ryan, A. J.; Whipple, K. X.; Johnson, J. P.

    2012-12-01

    Tributary canyons with amphitheater-shaped heads have previously been interpreted as evidence for groundwater seepage erosion, particularly in environments where fluvial processes are assumed to be negligible. However, some have questioned whether this canyon morphology is truly diagnostic of a particular formative process. We seek to determine the relative roles of fluvial and groundwater-related processes and the strength of stratigraphic control on the Colorado Plateau through a combination of fieldwork and GIS analysis. Amphitheater valleys may have overhanging or steep-sided headwalls with a semicircular plan-view pattern. It is reasonable to assume that this form is a result of focused erosion at the base of the headwall (i.e. sapping). Two frequently cited agents may lead to undermining: plunge-pool scour at the base of waterfalls and seepage induced weathering and erosion where the groundwater table intersects the land surface. Both processes are enhanced where weaker, less permeable layers underlie stronger cap rock. We conducted preliminary fieldwork in two locations on the Colorado Plateau, where there are many classic examples of amphitheater headed canyons. The Escalante River landscape is highly variable with a range of canyon and valley-head forms, many of which cut through the thick Navajo Sandstone into the underlying shale and sand of the Kayenta Formation. Northeast of Escalante National Monument, at the base of the Henry Mountains, is Tarantula Mesa. The canyons there are also considerably variable, with nearly all containing at least one abrupt amphitheater knickpoint at the valley head or farther downstream. Our observations are presented here with an analysis of the canyon profiles, surrounding topography, and potential structural controls. We have found that nearly all amphitheaters in both locales show signs of groundwater seepage weathering and plausibly seepage erosion. However, many also contain plunge pools and evidence of substantial

  14. Review of the Diablo Canyon probabilistic risk assessment

    International Nuclear Information System (INIS)

    Bozoki, G.E.; Fitzpatrick, R.G.; Bohn, M.P.; Sabek, M.G.; Ravindra, M.K.; Johnson, J.J.

    1994-08-01

    This report details the review of the Diablo Canyon Probabilistic Risk Assessment (DCPRA). The study was performed under contract from the Probabilistic Risk Analysis Branch, Office of Nuclear Reactor Research, USNRC by Brookhaven National Laboratory. The DCPRA is a full scope Level I effort and although the review touched on all aspects of the PRA, the internal events and seismic events received the vast majority of the review effort. The report includes a number of independent systems analyses sensitivity studies, importance analyses as well as conclusions on the adequacy of the DCPRA for use in the Diablo Canyon Long Term Seismic Program

  15. Update report on fracture flow in saturated tuff: Dynamic transport task for the Nevada Nuclear Waste Investigations

    International Nuclear Information System (INIS)

    Janecky, D.R.; Rundberg, R.S.; Ott, M.; Mitchell, A.

    1990-11-01

    This report summarizes the results of continuing experiments on the behavior of tracers during fracture flow in saturated, welded tuff. These experiments were completed during the past year as part of the Dynamic Transport Task of geochemical investigations for the Yucca Mountain Project sponsored by the US Department of Energy. These experiments are designed to investigate the effects of fluid movement in fractures when coupled with matrix diffusion and sorption but isolated from the effects of capillary suction and two-phase flow characteristic of unsaturated conditions. The experiments reported here are continuations of experimental efforts reported previously. The behavior of three tracers [HTO (tritiated water), TcO 4 - (pertechnetate), and sulforhodamine B dye] have been investigated during flow through a saturated column of densely welded tuff from the Topopah Spring Member of the Paintbrush Tuff, Yucca Mountain, Nye County, southern Nevada. 31 refs., 26 figs., 2 tabs

  16. Pore-water extraction from unsaturated tuff by triaxial and one-dimensional compression methods, Nevada Test Site, Nevada

    International Nuclear Information System (INIS)

    Mower, T.E.; Higgins, J.D.; Yang, In C.; Peters, C.A.

    1994-01-01

    The hydrologic system in the unsaturated tuff at Yucca Mountain, Nevada, is being evaluated for the US Department of Energy by the Yucca Mountain Project Branch of the US Geological Survey as a potential site for a high-level radioactive-waste repository. Part of this investigation includes a hydrochemical study that is being made to assess characteristics of the hydrologic system such as: traveltime, direction of flow, recharge and source relations, and types and magnitudes of chemical reactions in the unsaturated tuff. In addition, this hydrochemical information will be used in the study of the dispersive and corrosive effects of unsaturated-zone water on the radioactive-waste storage canisters. This report describes the design and validation of laboratory experimental procedures for extracting representative samples of uncontaminated pore water from welded and nonwelded, unsaturated tuffs from the Nevada Test Site

  17. Effects of tuff waste package components on release from 76-68 simulated waste glass: Final report

    International Nuclear Information System (INIS)

    McVay, G.L.; Robinson, G.R.

    1984-04-01

    An experimental matrix has been conducted that will allow evaluation of the effects of waste package constituents on the waste form release behavior in a tuff repository environment. Tuff rock and groundwater were used along with 304L, 316, and 1020M ferrous metals to evaluate release from uranium-doped MCC 76-68 simulated waste glass. One of the major findings was that in the absence of 1020M mild steel, tuff rock powder dominates the system. However, when 1020M mild steel is present, it appears to dominate the system. The rock-dominated system results in suppressed glass-water reaction and leaching while the 1020M-dominated system results in enhanced leaching - but the metal effectively scavenges uranium from solution. The 300-series stainless steels play no significant role in affecting glass leaching characteristics. 6 refs., 28 figs., 5 tabs

  18. Methodology for determining time-dependent mechanical properties of tuff subjected to near-field repository conditions

    International Nuclear Information System (INIS)

    Blacic, J.D.; Andersen, R.

    1983-01-01

    We have established a methodology to determine the time dependence of strength and transport properties of tuff under conditions appropriate to a nuclear waste repository. Exploratory tests to determine the approximate magnitudes of thermomechanical property changes are nearly complete. In this report we describe the capabilities of an apparatus designed to precisely measure the time-dependent deformation and permeability of tuff at simulated repository conditions. Preliminary tests with this new apparatus indicate that microclastic creep failure of tuff occurs over a narrow strain range with little precursory Tertiary creep behavior. In one test, deformation under conditions of slowly decreasing effective pressure resulted in failure, whereas some strain indicators showed a decreasing rate of strain

  19. Methodology for determining time-dependent mechanical properties of tuff subjected to near-field repository conditions

    Energy Technology Data Exchange (ETDEWEB)

    Blacic, J.D.; Andersen, R.

    1983-01-01

    We have established a methodology to determine the time dependence of strength and transport properties of tuff under conditions appropriate to a nuclear waste repository. Exploratory tests to determine the approximate magnitudes of thermomechanical property changes are nearly complete. In this report we describe the capabilities of an apparatus designed to precisely measure the time-dependent deformation and permeability of tuff at simulated repository conditions. Preliminary tests with this new apparatus indicate that microclastic creep failure of tuff occurs over a narrow strain range with little precursory Tertiary creep behavior. In one test, deformation under conditions of slowly decreasing effective pressure resulted in failure, whereas some strain indicators showed a decreasing rate of strain.

  20. Sorption-desorption studies on tuff III. A continuation of studies with samples from Jackass Flats and Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Wolfsberg, K.; Aguilar, R.D.; Bayhurst, B.P.

    1981-05-01

    This report is the third in a series of reports describing studies of sorption and migration of radionuclides in tuff. The investigations were extended to lithologies of tuff not previously studied. Continuing experiments with uranium, plutonium, and americium are described. The dependence of sorption on the concentration of the sorbing element and on the solution-to-solid ratio was investigated for a number of nuclides and two lithologies. A circulating system was designed for measuring sorption ratios. Values obtained from this system, batch measurements, and column elutions are compared. Progress on measuring and controlling Eh is described

  1. Thermal analyses for a nuclear-waste repository in tuff using USW-G1 borehole data

    International Nuclear Information System (INIS)

    Johnson, R.L.

    1982-10-01

    Thermal calculations using properties of tuffs obtained from the USW-G1 borehole, located near the SW margin of the Nevada Test Site (NTS), have been completed for a nuclear waste repository sited in welded tuff below the water table. The analyses considered two wasteforms, high level waste and spent fuel, emplaced at two different, gross thermal loadings, 50 and 75 kW/Acre (20.24 and 30.36 kW/ha). Calculations were made assuming that no boiling of the groundwater occurs; i.e., that the hydrostatic head potential was reestablished soon after waste emplacement. 23 figures, 2 tables

  2. Juvenile fragment studies on lapilli tuffs of the Messel maar-diatreme-volcano, Germany: implications for rockmagnetic properties

    Science.gov (United States)

    Nitzsche, T.; de Wall, H.; Rolf, C.; Schuessler, U.

    2006-12-01

    In 2001 the 433 m deep Messel 2001 bore hole was drilled in the centre of the Messel Pit, 25 km south of Frankfurt (Germany). Interdisciplinary, geoscientific results obtained from this drilling proved the origin of the circular-shaped basin as a maar-diatreme-structure beneath the surface. Recovered deposits consist of sedimentary rocks (0-240 m) and volcaniclastic rocks such as lapilli tuffs (240-373 m) as well as rocks of the underlying diatreme breccia (373-433 m). The lapilli tuffs, as matter of interest here, show little differentiation on a macro- and microscopic scale and appear as unsorted volcaniclastics with dominating juvenile lapilli and accidental clasts in the range of (sub)millimetres to centimetres in diameter. Decimeter-sized blocks of the crystalline basement occur at certain depths, but are comparatively scarce and inconspicuous, concerning the total thickness of the tuffs. Rock magnetic properties measured on core samples of the lapilli tuffs explain the origin of detected downhole magnetic anomalies performed during the drilling project 2001. Thereby, the juvenile fragments as main carrier of ferrimagnetic minerals (titano-magnetites) specify the rock magnetic character of the volcanic material and account for downhole logging data of the magnetic susceptibility (MS) and the natural remanent magnetisation (NRM). Besides similar remanence acquisition properties throughout the lapilli tuffs, differences in the magnetic stability behaviour are realised for the upper and lower half of the tuffs. Thermal magnetic experiments prove the magnetic differences and the acquisition of (partial) thermal remanent magnetisation (pTRM), respectively, and allow estimations of emplacement temperatures 300 ° C for the lower half of the lapilli tuffs. This study deals with image analytical and geochemical investigations on juvenile fragments as implication for the rock magnetic results and provides insights into the heat and magma source of the Messel maar

  3. Passive air exchanges between building and urban canyon via openings in a single facade

    International Nuclear Information System (INIS)

    Syrios, K.; Hunt, G.R.

    2008-01-01

    The results of an experimental study examining the steady exchange of air and heat between a building and an urban canyon are presented. The focus is on the effect of the canyon aspect ratio on the airflow through openings made exclusively in one side of the building. The interaction of the external wind flow and the internal thermally-driven flow was shown to depend upon the ratio of the building height H b to the canyon width W (distance between buildings forming the canyons). The trends observed as this aspect ratio (H b /W) was varied allow for identification of canyon geometries that yield reduced or enhanced building ventilation airflow rates

  4. Slope stability and rockfall assessment of volcanic tuffs using RPAS with 2-D FEM slope modelling

    Science.gov (United States)

    Török, Ákos; Barsi, Árpád; Bögöly, Gyula; Lovas, Tamás; Somogyi, Árpád; Görög, Péter

    2018-02-01

    Steep, hardly accessible cliffs of rhyolite tuff in NE Hungary are prone to rockfalls, endangering visitors of a castle. Remote sensing techniques were employed to obtain data on terrain morphology and to provide slope geometry for assessing the stability of these rock walls. A RPAS (Remotely Piloted Aircraft System) was used to collect images which were processed by Pix4D mapper (structure from motion technology) to generate a point cloud and mesh. The georeferencing was made by Global Navigation Satellite System (GNSS) with the use of seven ground control points. The obtained digital surface model (DSM) was processed (vegetation removal) and the derived digital terrain model (DTM) allowed cross sections to be drawn and a joint system to be detected. Joint and discontinuity system was also verified by field measurements. On-site tests as well as laboratory tests provided additional engineering geological data for slope modelling. Stability of cliffs was assessed by 2-D FEM (finite element method). Global analyses of cross sections show that weak intercalating tuff layers may serve as potential slip surfaces. However, at present the greatest hazard is related to planar failure along ENE-WSW joints and to wedge failure. The paper demonstrates that RPAS is a rapid and useful tool for generating a reliable terrain model of hardly accessible cliff faces. It also emphasizes the efficiency of RPAS in rockfall hazard assessment in comparison with other remote sensing techniques such as terrestrial laser scanning (TLS).

  5. Stable isotopes of authigenic minerals in variably-saturated fractured tuff

    Energy Technology Data Exchange (ETDEWEB)

    Weber, D.S.; Evans, D.D.

    1988-11-01

    Identifying stable isotope variation and mineralogical changes in fractured rock may help establish the history of climatic and geomorphological processes that might affect the isolation properties of a waste repository site. This study examines the use of the stable isotope ratios of oxygen ({sup 18}O/{sup 16}O) and carbon ({sup 13}C/{sup 12}C) in authigenic minerals as hydrogeochemical tools tracing low-temperature rock-water interaction in variably-saturated fractured stuff. Isotopic compositions of fracture-filling and rock matrix minerals in the Apache Leap tuff, near Superior, Arizona were concordant with geothermal temperatures and in equilibrium with water isotopically similar to present-day meteoric water and groundwater. Oxygen and carbon isotope ratios of fracture-filling, in unsaturated fractured tuff, displayed an isotopic gradient believed to result from near-surface isotopic enrichment due to evaporation rather than the effects of rock-water interaction. Oxygen isotope ratios of rock matrix opal samples exhibited an isotopic gradient believed to result from, leaching and reprecipitation of silica at depth. Methods and results can be used to further define primary flowpaths and the movement of water in variably-saturated fractured rock. 71 refs., 23 figs., 3 tabs.

  6. Slope stability and rockfall assessment of volcanic tuffs using RPAS with 2-D FEM slope modelling

    Directory of Open Access Journals (Sweden)

    Á. Török

    2018-02-01

    Full Text Available Steep, hardly accessible cliffs of rhyolite tuff in NE Hungary are prone to rockfalls, endangering visitors of a castle. Remote sensing techniques were employed to obtain data on terrain morphology and to provide slope geometry for assessing the stability of these rock walls. A RPAS (Remotely Piloted Aircraft System was used to collect images which were processed by Pix4D mapper (structure from motion technology to generate a point cloud and mesh. The georeferencing was made by Global Navigation Satellite System (GNSS with the use of seven ground control points. The obtained digital surface model (DSM was processed (vegetation removal and the derived digital terrain model (DTM allowed cross sections to be drawn and a joint system to be detected. Joint and discontinuity system was also verified by field measurements. On-site tests as well as laboratory tests provided additional engineering geological data for slope modelling. Stability of cliffs was assessed by 2-D FEM (finite element method. Global analyses of cross sections show that weak intercalating tuff layers may serve as potential slip surfaces. However, at present the greatest hazard is related to planar failure along ENE–WSW joints and to wedge failure. The paper demonstrates that RPAS is a rapid and useful tool for generating a reliable terrain model of hardly accessible cliff faces. It also emphasizes the efficiency of RPAS in rockfall hazard assessment in comparison with other remote sensing techniques such as terrestrial laser scanning (TLS.

  7. Stable isotopes of authigenic minerals in variably-saturated fractured tuff

    International Nuclear Information System (INIS)

    Weber, D.S.; Evans, D.D.

    1988-11-01

    Identifying stable isotope variation and mineralogical changes in fractured rock may help establish the history of climatic and geomorphological processes that might affect the isolation properties of a waste repository site. This study examines the use of the stable isotope ratios of oxygen ( 18 O/ 16 O) and carbon ( 13 C/ 12 C) in authigenic minerals as hydrogeochemical tools tracing low-temperature rock-water interaction in variably-saturated fractured stuff. Isotopic compositions of fracture-filling and rock matrix minerals in the Apache Leap tuff, near Superior, Arizona were concordant with geothermal temperatures and in equilibrium with water isotopically similar to present-day meteoric water and groundwater. Oxygen and carbon isotope ratios of fracture-filling, in unsaturated fractured tuff, displayed an isotopic gradient believed to result from near-surface isotopic enrichment due to evaporation rather than the effects of rock-water interaction. Oxygen isotope ratios of rock matrix opal samples exhibited an isotopic gradient believed to result from, leaching and reprecipitation of silica at depth. Methods and results can be used to further define primary flowpaths and the movement of water in variably-saturated fractured rock. 71 refs., 23 figs., 3 tabs

  8. Clinoptilolite compositions in diagenetically-altered tuffs at a potential nuclear waste repository, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Broxton, D.E.

    1987-01-01

    The compositions of Yucca Mountain clinoptilolites and their host tuffs are highly variable. Clinoptilolites and heulandites in fractures near the repository and in a thin, altered zone at the top of the Topopah Spring basal vitrophyre have consistent calcium-rich compositions. Below this level, clinoptilolites in thick zones of diagenetic alteration on the east side of Yucca Mountain have calcic-potassic compositions and become more calcium rich with depth. Clinoptilolites in stratigraphically equivalent tuffs to the west have sodic-potassic compositions and become more sodic with depth. Clinoptilolite properties important for repository performance assessment include thermal expansion/contraction behavior, hydration/dehydration behavior, and ion-exchange properties. These properties can be significantly affected by clinoptilolite compositions. The compositional variations for clinoptilolites found by this study suggest that the properties will vary vertically and laterally at Yucca Mountain. Used in conjunction with experimental data, the clinoptilolite compositions presented here can be used to model the behavior of clinoptilolites in the repository environment and along transport pathways

  9. Selection of candidate canister materials for high-level nuclear waste containment in a tuff repository

    International Nuclear Information System (INIS)

    McCright, R.D.; Weiss, H.; Juhas, M.C.; Logan, R.W.

    1983-11-01

    A repository located at Yucca Mountain at the Nevada Test Site is a potential site for permanent geological disposal of high-level nuclear waste. The repository can be located in a horizon in welded tuff, a volcanic rock, which is above the static water level at this site. The environmental conditions in this unsaturated zone are expected to be air and water vapor dominated for much of the containment period. Type 304L stainless steel is the reference material for fabricating canisters to contain the solid high-level wastes. Alternative stainless alloys are considered because of possible susceptibility of 304L to localized and stress forms of corrosion. For the reprocessed glass wastes, the canisters serve as the recipient for pouring the glass with the result that a sensitized microstructure may develop because of the times at elevated temperatures. Corrosion testing of the reference and alternative materials has begun in tuff-conditioned water and steam environments. 21 references, 8 figures, 8 tables

  10. Geotechnical instrumentation requirements for atdepth testing and repository monitoring in tuff

    International Nuclear Information System (INIS)

    Zimmerman, R.M.

    1983-01-01

    This paper outlines geotechnical instrumentation requirements for the possible establishment of a nuclear waste repository in tuff on the Nevada Test Site (NTS). The Nuclear Regulatory Commission (NRC) has specified a continuing program to confirm performance during the operational period of the repository, which could last 50 years. Minimum required geotechnical measurements for confirmation of performance include thermal and thermomechanical responses; changes in stress, strain, and displacements; and pore pressure and groundwater flow characteristics. Conditions expected in tuff are: maximum rock temperatures of less than 250 0 C, stresses less than 100 MPa, strains between + or -0.01 mm/mm, and pore pressures less than 35 KPa in the unsaturated zone where hydraulic head is not the primary contributor. The paper describes instrumentation needed to make the desired measurements. In general, the instrumentation and data system are required to be stable and reliable for tens of years. Designs must consider requirements for temperature stability, temperature expansion compensation, moisture resistance, and long-term durability in mining-type environments. Severe requirements such as these suggest consideration of techniques for in-situ replacement of instrumentation. State-of-the-art instrumentation is briefly described along with a discussion of needs for refinement, replacement/recalibration and instrumentation development

  11. Containment barrier metals for high-level waste packages in a Tuff repository

    Energy Technology Data Exchange (ETDEWEB)

    Russell, E.W.; McCright, R.D.; O`Neal, W.C.

    1983-10-12

    The Nevada Nuclear Waste Storage Investigations (NNWSI) Waste Package project is part of the US Department of Energy`s Civilian Radioactive Waste Management (CRWM) Program. The NNWSI project is working towards the development of multibarriered packages for the disposal of spent fuel and high-level waste in tuff in the unsaturated zone at Yucca Mountain at the Nevada Test Site (NTS). The final engineered barrier system design may be composed of a waste form, canister, overpack, borehole liner, packing, and the near field host rock, or some combination thereof. Lawrence Livermore National Laboratory`s (LLNL) role is to design, model, and test the waste package subsystem for the tuff repository. At the present stage of development of the nuclear waste management program at LLNL, the detailed requirements for the waste package design are not yet firmly established. In spite of these uncertainties as to the detailed package requirements, we have begun the conceptual design stage. By conceptual design, we mean design based on our best assessment of present and future regulatory requirements. We anticipate that changes will occur as the detailed requirements for waste package design are finalized. 17 references, 4 figures, 10 tables.

  12. Containment barrier metals for high-level waste packages in a Tuff repository

    International Nuclear Information System (INIS)

    Russell, E.W.; McCright, R.D.; O'Neal, W.C.

    1983-01-01

    The Nevada Nuclear Waste Storage Investigations (NNWSI) Waste Package project is part of the US Department of Energy's Civilian Radioactive Waste Management (CRWM) Program. The NNWSI project is working towards the development of multibarriered packages for the disposal of spent fuel and high-level waste in tuff in the unsaturated zone at Yucca Mountain at the Nevada Test Site (NTS). The final engineered barrier system design may be composed of a waste form, canister, overpack, borehole liner, packing, and the near field host rock, or some combination thereof. Lawrence Livermore National Laboratory's (LLNL) role is to design, model, and test the waste package subsystem for the tuff repository. At the present stage of development of the nuclear waste management program at LLNL, the detailed requirements for the waste package design are not yet firmly established. In spite of these uncertainties as to the detailed package requirements, we have begun the conceptual design stage. By conceptual design, we mean design based on our best assessment of present and future regulatory requirements. We anticipate that changes will occur as the detailed requirements for waste package design are finalized. 17 references, 4 figures, 10 tables

  13. Reaction of Bullfrog tuff with J-13 well water at 900C and 1500C

    International Nuclear Information System (INIS)

    Oversby, V.M.; Knauss, K.G.

    1983-01-01

    A series of experiments was conducted on crushed tuff at 90 0 C and 150 0 C and on core wafer samples at 150 0 C. The results show the following: increasing the ratio of rock to water increases the rate of approach to steady-state concentrations in solution. Surface outcrop samples of Bullfrog tuff contain a minor component of highly soluble material believed to be a residue from the evaporation of surface runoff water in the pores of the rock. This material can be removed by shaking the crushed rock with water at room temperature and subjecting it briefly to heat with fresh water. Solution analyses for unfiltered samples that have reacted for short periods show higher concentrations of Al and Fe than do analyses for filtered samples; results for other elements are independent of filtration. This difference probably exists because of particulate matter in the solutions that dissolves when the samples are acidified prior to analysis. Agitation of samples during reaction produces sub-0.1 μ particles in the solutions. These particles dissolve when samples are acidified, resulting in abnormally high concentration values for some elements, such as Al and Fe. Comparison of the results for crushed rock with those for core wafers shows that the method of sample preparation does not have a large effect on the results of rock-water interaction studies

  14. Version II of the users manual for the Tuff Data Base Interface

    International Nuclear Information System (INIS)

    Welch, E.P.; Satter, B.J.; Langkopf, B.S.; Zeuch, D.H.

    1987-05-01

    The Nevada Nuclear Waste Storage Investigations (NNWSI) Project, managed by the Nevada Operations Office of the US Department of Energy, is investigating the feasibility of locating a repository at Yucca Mountain on and adjacent to the Nevada Test Site (NTS) in southern Nevada. A part of this investigation includes obtaining physical properties from laboratory tests on samples from Yucca Mountain and from field tests at Yucca Mountain. A computerized data base has been developed to store this data in a centralized location. The data base is stored on the Cyber 170/855 computer at Sandia using the System 2000 Data Base Management software. A user-friendly interface, the Tuff Data Base Interface (the Interface), allows NNWSI participants to retrieve data from the Tuff Data Base. The Interface gives users flexibility to retrieve portions of the Data Base related to their interests. This report gives basic instructions on accessing the Sandia computing system and explains how to use the Interface. 18 figs., 5 tabs

  15. Stress-corrosion-cracking studies on candidate container alloys for the Tuff Repository

    International Nuclear Information System (INIS)

    Beavers, J.A.; Durr, C.L.

    1992-05-01

    Cortest Columbus Technologies, Inc. (CC Technologies) investigated the long-term performance of container materials used for high-level waste package as part of the information needed by the Nuclear Regulatory Commission (NRC) to assess the Department of Energy's application to construct to geologic repository for high-level radioactive waste. At the direction of the NRC, the program focused on the Tuff Repository. This report summarizes the results of Stress-Corrosion-Cracking (SCC) studies performed in Tasks 3, 5, and 7 of the program. Two test techniques were used; U-bend exposures and Slow-Strain-Rate (SSR) tests. The testing was performed on two copper-base alloys (Alloy CDA 102 and Alloy CDA 175) and two Fe-Cr-Ni alloys (Alloy 304L and Alloy 825) in simulated J-13 groundwater and other simulated solutions for the Tuff Repository. These solutions were designed to simulate the effects of concentration and irradiation on the groundwater composition. All SCC testing on the Fe-Cr-Ni Alloys was performed on solution-annealed specimens and thus issues such as the effect of sensitization on SCC were not addressed

  16. Behavior of stressed and unstressed 304L specimens in tuff repository environmental conditions

    International Nuclear Information System (INIS)

    Juhas, M.C.; McCright, R.D.; Garrison, R.E.

    1984-11-01

    This paper presents preliminary results of an investigation of the behavior of candidate barrier material for high-level nuclear waste storage, Type 304L stainless steel, in tuff repository environmental conditions. Tuff is a densely welded, devitrified, igneous rock common to the proposed repository site at Yucca Mountain, Nevada. The results discussed include: irradiation corrosion tests, U-bend irradiation corrosion tests, slow strain rate tests, and bent beam stress corrosion tests. Results indicate that Type 304L stainless steel shows excellent resistance to general, localized, and stress corrosion under the environmental and microstructural conditions tested so far. The environmental test conditions are 50 to 100 0 C J-13 well water (non-saline, near neutral pH, and oxic in nature) and saturated steam at 100 0 C. Microstructural conditions include solution annealed and long furnace heat treatments to provoke a sensitized structure. However, this particular type of stainless steel may be susceptible to long-term, low-temperature sensitization because of the combination of expected time at elevated temperature and residual stress in the container after emplacement in the repository. Other grades of austenitic stainless steels are reported to be more resistant to low-temperature sensitization. Future work will therefore include more extensive testing of these grades. 15 references, 5 figures, 7 tables

  17. Conceptualization of a hypothetical high-level nuclear waste repository site in unsaturated, fractured tuff

    International Nuclear Information System (INIS)

    Parsons, A.M.; Olague, N.E.; Gallegos, D.P.

    1991-01-01

    Under the sponsorship of the US Nuclear Regulatory Commission (NRC), Sandia National Laboratories (SNL) is developing a performance assessment methodology for the analysis of long-term disposal and isolation of high-level nuclear wastes (HLW) in alternative geologic media. As part of this exercise, SNL created a conceptualization of ground-water flow and radionuclide transport in the far field of a hypothetical HLW repository site located in unsaturated, fractured tuff formations. This study provides a foundation for the development of conceptual mathematical, and numerical models to be used in this performance assessment methodology. This conceptualization is site specific in terms of geometry, the regional ground-water flow system, stratigraphy, and structure in that these are based on information from Yucca Mountain located on the Nevada Test Site. However, in terms of processes in unsaturated, fractured, porous media, the model is generic. This report also provides a review and evaluation of previously proposed conceptual models of unsaturated and saturated flow and solute transport. This report provides a qualitative description of a hypothetical HLW repository site in fractured tuff. However, evaluation of the current knowledge of flow and transport at Yucca Mountain does not yield a single conceptual model. Instead, multiple conceptual models are possible given the existing information

  18. Nuclear-waste-package program for high-level isolation in Nevada tuff

    International Nuclear Information System (INIS)

    Rothman, A.J.

    1982-01-01

    The objective of the waste package program is to insure that a package is designed suitable for a repository in tuff that meets performance requirements of the NRC. In brief, the current (draft) regulation requires that the radionuclides be contained in the engineered system for 1000 years, and that, thereafter, no more than one part in 10 5 of the nuclides per year leave the boundary of the system. Studies completed as of this writing are thermal modeling of waste packages in a tuff repository and analysis of sodium bentonite as a potential backfill material. Both studies will be presented. Thermal calculations coupled with analysis of the geochemical literature on bentonite indicate that extensive chemical and physical alteration of bentonite would result at the high power densities proposed (ca. 2 kW/package and an area density of 25 W/m 2 ), in part due to compacted bentonite's relatively low thermal conductivity when dehydrated (approx. 0.6 +- 0.2 W/m 0 C). Because our groundwater contains K + , an upper hydrothermal temperature limit appears to be 120 to 150 0 C. At much lower power densities (less than 1 kW per package and an areal density of 12 W/m 2 ), bentonite may be suitable

  19. Conceptualization of a hypothetical high-level nuclear waste repository site in unsaturated, fractured tuff

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, A.M.; Olague, N.E.; Gallegos, D.P. [Sandia National Labs., Albuquerque, NM (USA)

    1991-01-01

    Under the sponsorship of the US Nuclear Regulatory Commission (NRC), Sandia National Laboratories (SNL) is developing a performance assessment methodology for the analysis of long-term disposal and isolation of high-level nuclear wastes (HLW) in alternative geologic media. As part of this exercise, SNL created a conceptualization of ground-water flow and radionuclide transport in the far field of a hypothetical HLW repository site located in unsaturated, fractured tuff formations. This study provides a foundation for the development of conceptual mathematical, and numerical models to be used in this performance assessment methodology. This conceptualization is site specific in terms of geometry, the regional ground-water flow system, stratigraphy, and structure in that these are based on information from Yucca Mountain located on the Nevada Test Site. However, in terms of processes in unsaturated, fractured, porous media, the model is generic. This report also provides a review and evaluation of previously proposed conceptual models of unsaturated and saturated flow and solute transport. This report provides a qualitative description of a hypothetical HLW repository site in fractured tuff. However, evaluation of the current knowledge of flow and transport at Yucca Mountain does not yield a single conceptual model. Instead, multiple conceptual models are possible given the existing information.

  20. Fluid flow in 0.5-m scale blocks of Topopah Spring tuff

    International Nuclear Information System (INIS)

    Blair, S. C.; Carlson, S. R.; Constantino, M. S.

    1999-01-01

    A laboratory experiment was conducted on a 0.5-m scale block of Topopah Spring tuff, to measure fluid flow and mechanical deformation properties under conditions that approximate the near-field environment of a potential nuclear waste repository, and to provide an intermediate-scale test case for numerical model validation. The test specimen is a 0.25 x 0.25 x 0.50 m rectangular prism bisected by an artificial (saw-cut) fracture orthogonal to the tuff fabric. Water was supplied by a point source at the center of the fracture under various pressures of up to 0.04 MPa. Both fluid flow and mechanical properties were found to be anisotropic and strongly correlated with the ash flow fabric. Fluid mass-balance measurements revealed that only minor imbibition of water occurred through the fracture surfaces and that flow rates were independent of normal stress to 14.0 MPa and temperature to 140 C. Flow through the fracture occurred largely through uncorrelated porosity that intersected the fracture plane

  1. Submarine canyons as coral and sponge habitat on the eastern Bering Sea slope

    Directory of Open Access Journals (Sweden)

    Robert J. Miller

    2015-07-01

    Full Text Available Submarine canyons have been shown to positively influence pelagic and benthic biodiversity and ecosystem function. In the eastern Bering Sea, several immense canyons lie under the highly productive “green belt” along the continental slope. Two of these, Pribilof and Zhemchug canyons, are the focus of current conservation interest. We used a maximum entropy modeling approach to evaluate the importance of these two canyons, as well as canyons in general, as habitat for gorgonian (alcyonacean corals, pennatulacean corals, and sponges, in an area comprising most of the eastern Bering Sea slope and outer shelf. These invertebrates create physical structure that is a preferred habitat for many mobile species, including commercially important fish and invertebrates. We show that Pribilof canyon is a hotspot of structure-forming invertebrate habitat, containing over 50% of estimated high-quality gorgonian habitat and 45% of sponge habitat, despite making up only 1.7% of the total study area. The amount of quality habitat for gorgonians and sponges varied in other canyons, but canyons overall contained more high-quality habitat for structure-forming invertebrates compared to other slope areas. Bottom trawling effort was not well correlated with habitat quality for structure-forming invertebrates, and bottom-contact fishing effort in general, including longlining and trawling, was not particularly concentrated in the canyons examined. These results suggest that if conserving gorgonian coral habitat is a management goal, canyons, particularly Pribilof Canyon, may be a prime location to do this without excessive impact on fisheries.

  2. Carbonaceous aerosol particles from common vegetation in the Grand Canyon

    International Nuclear Information System (INIS)

    Hallock, K.A.; Mazurek, M.A.; Cass, G.R.

    1992-05-01

    The problem of visibility reduction in the Grand Canyon due to fine organic aerosol particles in the atmosphere has become an area of increased environmental concern. Aerosol particles can be derived from many emission sources. In this report, we focus on identifying organic aerosols derived from common vegetation in the Grand Canyon. These aerosols are expected to be significant contributors to the total atmospheric organic aerosol content. Aerosol samples from living vegetation were collected by resuspension of surface wax and resin components liberated from the leaves of vegetation common to areas of the Grand Canyon. The samples were analyzed using high-resolution gas chromatography/mass spectrometry (GC/MS). Probable identification of compounds was made by comparison of sample spectra with National Institute of Standards and Technology (NIST) mass spectral references and positive identification of compounds was made when possible by comparison with authentic standards as well as NIST references. Using these references, we have been able to positively identify the presence of n-alkane and n-alkanoic acid homolog series in the surface waxes of the vegetation sampled. Several monoterpenes, sesquiterpenes, and diterpenes were identified also as possible biogenic aerosols which may contribute to the total organic aerosol abundance leading to visibility reduction in the Grand Canyon

  3. 77 FR 9265 - Glen Canyon Dam Adaptive Management Work Group

    Science.gov (United States)

    2012-02-16

    ... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group... Adaptive Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning.... L. 102-575) of 1992. The AMP includes a Federal advisory committee, the AMWG, a technical work group...

  4. Aerodynamic effects of trees on pollutant concentration in street canyons

    NARCIS (Netherlands)

    Buccolieri, R.; Gromke, C.B.; Sabatino, Di S.; Ruck, B.

    2009-01-01

    This paper deals with aerodynamic effects of avenue-like tree planting on flow and traffic-originated pollutant dispersion in urban street canyons by means of wind tunnel experiments and numerical simulations. Several parameters affecting pedestrian level concentration are investigated, namely plant

  5. Sedimentary characteristics of samples collected from some submarine canyons

    NARCIS (Netherlands)

    Bouma, Arnold H.

    Oriented rectangular cores of 20.3 × 30.5 cm and 45.7 cm high have been collected in a number of submarine canyons off southern California (U.S.A.) and off the southern tip of Baja California (Mexico) for a detailed study of their sedimentary structures. By applying several methods, mainly X-ray

  6. Research on the calculation method of shale and tuff content: taking tuffaceous reservoirs of X depression in the Hailar–Tamtsag Basin as an example

    International Nuclear Information System (INIS)

    Liu, Sihui; Huang, Buzhou; Pan, Baozhi; Guo, Yuhang; Fang, Chunhui; Wang, Guiping; Sun, Fengxian; Qiu, Haibo; Jiang, Bici

    2015-01-01

    Shale content is known in reservoir evaluation as an important parameter in well logging. However, the log response characteristics are simultaneously affected by shale and tuff existing in tuffaceous sandstone reservoirs. Due to the fact that tuff content exerts an influence on the calculation of shale content, the former is equally important as the latter. Owing to the differences in the source and composition between shale and tuff, the calculation of tuff content using the same methods for shale content cannot meet the accuracy requirements of logging evaluation. The present study takes the tuffaceous reservoirs in the X depression of the Hailar–Tamtsag Basin as an example. The differences in the log response characteristics between shale and tuff are theoretically analyzed and verified using core analysis data. The tuff is then divided into fine- and coarse-grained fractions, according to the differences in the distribution of the radioactive elements, uranium, thorium and potassium. Next, a volume model suitable for tuffaceous sandstone reservoirs is established to include a sandstone matrix, shale, fine-grained tuff, coarse-grained tuff and pore. A comparison of three optimization algorithms shows that the particle swarm optimization (PSO) yields better calculation results with small mean errors. The resistivity differences among shale, fine-grained tuff and coarse-grained tuff are considered in the calculation of saturation. The water saturation of tuffaceous reservoirs is computed using the improved Poupon’s equation, which is suitable for tuffaceous sandstone reservoirs with low water salinity. The method is used in well Y, and is shown to have a good application effect. (paper)

  7. Small Mammal Sampling in Mortandad and Los Alamos Canyons, 2005

    International Nuclear Information System (INIS)

    Kathy Bennett; Sherri Sherwood; Rhonda Robinson

    2006-01-01

    As part of an ongoing ecological field investigation at Los Alamos National Laboratory, a study was conducted that compared measured contaminant concentrations in sediment to population parameters for small mammals in the Mortandad Canyon watershed. Mortandad Canyon and its tributary canyons have received contaminants from multiple solid waste management units and areas of concern since establishment of the Laboratory in the 1940s. The study included three reaches within Effluent and Mortandad canyons (E-1W, M-2W, and M-3) that had a spread in the concentrations of metals and radionuclides and included locations where polychlorinated biphenyls and perchlorate had been detected. A reference location, reach LA-BKG in upper Los Alamos Canyon, was also included in the study for comparison purposes. A small mammal study was initiated to assess whether potential adverse effects were evident in Mortandad Canyon due to the presence of contaminants, designated as contaminants of potential ecological concern, in the terrestrial media. Study sites, including the reference site, were sampled in late July/early August. Species diversity and the mean daily capture rate were the highest for E-1W reach and the lowest for the reference site. Species composition among the three reaches in Mortandad was similar with very little overlap with the reference canyon. Differences in species composition and diversity were most likely due to differences in habitat. Sex ratios, body weights, and reproductive status of small mammals were also evaluated. However, small sample sizes of some species within some sites affected the analysis. Ratios of males to females by species of each site (n = 5) were tested using a Chi-square analysis. No differences were detected. Where there was sufficient sample size, body weights of adult small mammals were compared between sites. No differences in body weights were found. Reproductive status of species appears to be similar across sites. However, sample

  8. Small Mammal Sampling in Mortandad and Los Alamos Canyons, 2005

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, Kathy; Sherwood, Sherri; Robinson, Rhonda

    2006-08-15

    As part of an ongoing ecological field investigation at Los Alamos National Laboratory, a study was conducted that compared measured contaminant concentrations in sediment to population parameters for small mammals in the Mortandad Canyon watershed. Mortandad Canyon and its tributary canyons have received contaminants from multiple solid waste management units and areas of concern since establishment of the Laboratory in the 1940s. The study included three reaches within Effluent and Mortandad canyons (E-1W, M-2W, and M-3) that had a spread in the concentrations of metals and radionuclides and included locations where polychlorinated biphenyls and perchlorate had been detected. A reference location, reach LA-BKG in upper Los Alamos Canyon, was also included in the study for comparison purposes. A small mammal study was initiated to assess whether potential adverse effects were evident in Mortandad Canyon due to the presence of contaminants, designated as contaminants of potential ecological concern, in the terrestrial media. Study sites, including the reference site, were sampled in late July/early August. Species diversity and the mean daily capture rate were the highest for E-1W reach and the lowest for the reference site. Species composition among the three reaches in Mortandad was similar with very little overlap with the reference canyon. Differences in species composition and diversity were most likely due to differences in habitat. Sex ratios, body weights, and reproductive status of small mammals were also evaluated. However, small sample sizes of some species within some sites affected the analysis. Ratios of males to females by species of each site (n = 5) were tested using a Chi-square analysis. No differences were detected. Where there was sufficient sample size, body weights of adult small mammals were compared between sites. No differences in body weights were found. Reproductive status of species appears to be similar across sites. However, sample

  9. Thermal bioclimate in idealized urban street canyons in Campinas, Brazil

    Science.gov (United States)

    Abreu-Harbich, Loyde V.; Labaki, Lucila C.; Matzarakis, Andreas

    2014-01-01

    Among several urban design parameters, the height-to-width ratio (H/W) and orientation are important parameters strongly affecting thermal conditions in cities. This paper quantifies changes in thermal comfort due to typical urban canyon configurations in Campinas, Brazil, and presents urban guidelines concerning H/W ratios and green spaces to adapt urban climate change. The study focuses on thermal comfort issues of humans in urban areas and performs evaluation in terms of physiologically equivalent temperature (PET), based on long-term data. Meteorological data of air temperature, relative humidity, wind speed and solar radiation over a 7-year period (2003-2010) were used. A 3D street canyon model was designed with RayMan Pro software to simulate the influence of urban configuration on urban thermal climate. The following configurations and setups were used. The model canyon was 500 m in length, with widths 9, 21, and 44 m. Its height varied in steps of 2.5 m, from 5 to 40 m. The canyon could be rotated in steps of 15°. The results show that urban design parameters such as width, height, and orientation modify thermal conditions within street canyons. A northeast-southwest orientation can reduce PET during daytime more than other scenarios. Forestry management and green areas are recommended to promote shade on pedestrian areas and on façades, and to improve bioclimate thermal stress, in particular for H/W ratio less than 0.5. The method and results can be applied by architects and urban planners interested in developing responsive guidelines for urban climate issues.

  10. Savannah River Site: Canyons and associated facilities utilization study

    International Nuclear Information System (INIS)

    Ellison, D.; Dickenson, J.

    1995-01-01

    The Westinghouse Savannah River Company was asked by the U.S. Department of Energy (DOE) to study options for utilization of Savannah River Site (SRS) Canyons and Associated Facilities to support existing and potential future material stabilization and/or disposition missions. This report is WSRC's response to that request. It includes: (1) A compilation of pending DOE material stabilization and/or disposition decisions involving utilization of SRS canyons and associated facilities, including discussion of quantities and expected availability of materials for which SRS handling and/or processing capability is a reasonable alternative under consideration. (2) A description of SRS canyons and associated facilities affected by pending DOE material stabilization and/or disposition decisions, including discussion of material handling and/or processing capabilities and capacities. (3) A comparative evaluation of three proposed scenarios for SRS canyon utilization with respect to startup and operating schedules; annual and life cycle costs; impacts on completion of commitments in the DOE Implementation Plan (IP) for Defense Nuclear Facilities Safety Board (DNFSB) Recommendation 94-1; SRS ability to support alternatives under consideration in pending DOE materials stabilization and/or disposition decisions; and timing for potential transition to deactivation. (4) The sensitivity of the comparative evaluation of the three canyon utilization scenarios to the effect of the selection of other alternatives for individual stabilization missions or individual new missions. Briefings on the scope of this study have been presented to key representatives of several SRS public stakeholder groups. Briefings on the major conclusions from this study have been presented to WSRC Management, DOE-SR, EM-60, EM-1, and the DNFSB

  11. The volcanic foundation of Dutch architecture : Use of Rhenish tuff and trass in the Netherlands in the past two millennia

    NARCIS (Netherlands)

    Nijland, TG; van Hees, R.P.J.

    2016-01-01

    Occasionally, a profound but distant connection between volcano and culture exists. This is the case between the volcanic Eifel region in Germany and historic construction in the Netherlands, with the river Rhine as physical and enabling connection. Volcanic tuff from the Eifel comprises a

  12. The influence of water on the strength of Neapolitan Yellow Tuff, the most widely used building stone in Naples (Italy)

    Science.gov (United States)

    Heap, Michael J.; Farquharson, Jamie I.; Kushnir, Alexandra R. L.; Lavallée, Yan; Baud, Patrick; Gilg, H. Albert; Reuschlé, Thierry

    2018-06-01

    Neapolitan Yellow Tuff (NYT) has been used in construction in Naples (Italy) since the Greeks founded the city—then called Neapolis—in the sixth century BCE. We investigate here whether this popular building stone is weaker when saturated with water, an issue important for assessments of weathering damage and monument preservation. To this end, we performed 28 uniaxial compressive strength measurements on dry and water-saturated samples cored from a block of the lithified Upper Member of the NYT. Our experiments show that the strength of the zeolite-rich NYT is systematically reduced when saturated with water (the ratio of wet to dry strength is 0.63). Complementary experiments show that two other common Neapolitan building stones—Piperno Tuff and the grey Campanian Ignimbrite (both facies of the Campanian Ignimbrite deposit devoid of zeolites)—do not weaken when wet. From these data, and previously published data for tuffs around the globe, we conclude that the water-weakening in NYT is a consequence of the presence of abundant zeolites (the block tested herein contains 46 wt.% of zeolites). These data may help explain weathering damage in NYT building stones (due to rainfall, rising damp, and proximity to the sea or water table) and the observed link between rainfall and landslides, rock falls, and sinkhole formation in Naples, and the weathering of other buildings built from zeolite-rich tuffs worldwide.

  13. Permeability and fluid chemistry studies of the Topopah Spring Member of the Paintbrush Tuff, Nevada Test Site: Part II

    International Nuclear Information System (INIS)

    Moore, D.E.; Morrow, C.A.; Byerlee, J.D.

    1985-03-01

    The Topopah Spring Member of the Paintbrush Tuff is being considered as a possible emplacement horizon for the disposal of nuclear waste. The permeability and pore-fluid chemistry of the Topopah Spring Member have been investigated experimentally. The work reported here represents a continuation of previous permeability studies on the Topopah Spring Member. Three experiments were run, to test the effect of pore pressure, sample orientation, and flow direction on permeability and pore fluid chemistry. In the experiments, water flowed either up or down a temperature gradient established across the tuff sample in response to a small pore pressure gradient. The maximum temperature of the gradient was 150 0 C, and the minimum was 43 to 45 0 C. The confining pressure was 100 bars, corresponding to a disposal depth of 400 meters. J13 water was the starting pore fluid. The heated tuff samples showed few changes in permeability from their initial, room-temperature values. In addition, the fluids discharged from both the low and high-temperature sides of the tuff samples were dilute, nearly neutral solutions whose compositions did not differ greatly from the starting J13 compositions. 16 refs., 14 figs., 4 tabs

  14. Crystallization Stages of the Bishop Tuff Magma Body Recorded in Crystal Textures in Pumice Clasts

    Energy Technology Data Exchange (ETDEWEB)

    Pamukcu, Ayla; Gualda, Guilherme A.R.; Anderson, Jr. , Alfred T. (Vanderbilt); (UC)

    2012-07-25

    The Bishop Tuff is a giant silicic ignimbrite erupted at 0.76 Ma in eastern California, USA. Five pumice clasts from the late-erupted Bishop Tuff (Aeolian Buttes) were studied in an effort to better understand the pre- and syn-eruptive history of the Bishop magma body and place constraints on the timescales of its existence. This study complements and expands on a previous study that focused on early-erupted Bishop Tuff pumice clasts. Bulk densities of pumice clasts were measured using an immersion method, and phenocryst crystal contents were determined using a sieving and winnowing procedure. X-ray tomography was used to obtain qualitative and quantitative textural information, particularly crystal size distributions (CSDs). We have determined CSDs for crystals ranging in size from {approx}10 to {approx}1000 {micro}m for three groups of mineral phases: magnetite ({+-}ilmenite), pyroxene + biotite, quartz + feldspar. Similar to early-erupted pumice, late-erupted pumice bulk density and crystal contents are positively correlated, and comparison of crystal fraction vs size trends suggests that the proportion of large crystals is the primary control on crystallinity. Porosity is negatively correlated with crystal content, which is difficult to reconcile with closed-system crystallization. Magnetite and pyroxene + biotite size distributions are fractal in nature, often attributed to fragmentation; however, crystals are mostly whole and euhedral, such that an alternative mechanism is necessary to explain these distributions. Quartz + feldspar size distributions are kinked, with a shallow-sloped log-linear section describing large crystals (> 140 {micro}m) and a steep-sloped log-linear section describing small crystals (< 140 {micro}m). We interpret these two crystal populations as resulting from a shift in crystallization regime. We suggest that the shallow-sloped section describes a pre-eruptive quartz + feldspar growth-dominated regime, whereas the steep

  15. Magmatism, ash-flow tuffs, and calderas of the ignimbrite flareup in the western Nevada volcanic field, Great Basin, USA

    Science.gov (United States)

    Christopher D. Henry,; John, David A.

    2013-01-01

    The western Nevada volcanic field is the western third of a belt of calderas through Nevada and western Utah. Twenty-three calderas and their caldera-forming tuffs are reasonably well identified in the western Nevada volcanic field, and the presence of at least another 14 areally extensive, apparently voluminous ash-flow tuffs whose sources are unknown suggests a similar number of undiscovered calderas. Eruption and caldera collapse occurred between at least 34.4 and 23.3 Ma and clustered into five ∼0.5–2.7-Ma-long episodes separated by quiescent periods of ∼1.4 Ma. One eruption and caldera collapse occurred at 19.5 Ma. Intermediate to silicic lavas or shallow intrusions commonly preceded caldera-forming eruptions by 1–6 Ma in any specific area. Caldera-related as well as other magmatism migrated from northeast Nevada to the southwest through time, probably resulting from rollback of the formerly shallow-dipping Farallon slab. Calderas are restricted to the area northeast of what was to become the Walker Lane, although intermediate and effusive magmatism continued to migrate to the southwest across the future Walker Lane.Most ash-flow tuffs in the western Nevada volcanic field are rhyolites, with approximately equal numbers of sparsely porphyritic (≤15% phenocrysts) and abundantly porphyritic (∼20–50% phenocrysts) tuffs. Both sparsely and abundantly porphyritic rhyolites commonly show compositional or petrographic evidence of zoning to trachydacites or dacites. At least four tuffs have volumes greater than 1000 km3, with one possibly as much as ∼3000 km3. However, the volumes of most tuffs are difficult to estimate, because many tuffs primarily filled their source calderas and/or flowed and were deposited in paleovalleys, and thus are irregularly distributed.Channelization and westward flow of most tuffs in paleovalleys allowed them to travel great distances, many as much as ∼250 km (original distance) to what is now the western foothills of the

  16. Environmental analysis of Lower Pueblo/Lower Los Alamos Canyon, Los Alamos, New Mexico

    International Nuclear Information System (INIS)

    Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.; Becker, N.M.; Rodgers, J.C.; Hansen, W.R.

    1994-12-01

    The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, Pueblo Canyon, and Los Alamos Canyon found residual contamination at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons all the way to the Rio Grande. The largest reservoir of residual radioactivity is in lower Pueblo Canyon, which is on DOE property. However, residual radioactivity does not exceed proposed cleanup criteria in either lower Pueblo or lower Los Alamos Canyons. The three alternatives proposed are (1) to take no action, (2) to construct a sediment trap in lower Pueblo Canyon to prevent further transport of residual radioactivity onto San Ildefonso Indian Pueblo land, and (3) to clean the residual radioactivity from the canyon system. Alternative 2, to cleanup the canyon system, is rejected as a viable alternative. Thousands of truckloads of sediment would have to be removed and disposed of, and this effort is unwarranted by the low levels of contamination present. Residual radioactivity levels, under either present conditions or projected future conditions, will not result in significant radiation doses to persons exposed. Modeling efforts show that future transport activity will not result in any residual radioactivity concentrations higher than those already existing. Thus, although construction of a sediment trap in lower Pueblo Canyon is a viable alternative, this effort also is unwarranted, and the no-action alternative is the preferred alternative

  17. Environmental analysis of Lower Pueblo/Lower Los Alamos Canyon, Los Alamos, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.; Becker, N.M.; Rodgers, J.C.; Hansen, W.R.

    1994-12-01

    The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, Pueblo Canyon, and Los Alamos Canyon found residual contamination at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons all the way to the Rio Grande. The largest reservoir of residual radioactivity is in lower Pueblo Canyon, which is on DOE property. However, residual radioactivity does not exceed proposed cleanup criteria in either lower Pueblo or lower Los Alamos Canyons. The three alternatives proposed are (1) to take no action, (2) to construct a sediment trap in lower Pueblo Canyon to prevent further transport of residual radioactivity onto San Ildefonso Indian Pueblo land, and (3) to clean the residual radioactivity from the canyon system. Alternative 2, to cleanup the canyon system, is rejected as a viable alternative. Thousands of truckloads of sediment would have to be removed and disposed of, and this effort is unwarranted by the low levels of contamination present. Residual radioactivity levels, under either present conditions or projected future conditions, will not result in significant radiation doses to persons exposed. Modeling efforts show that future transport activity will not result in any residual radioactivity concentrations higher than those already existing. Thus, although construction of a sediment trap in lower Pueblo Canyon is a viable alternative, this effort also is unwarranted, and the no-action alternative is the preferred alternative.

  18. Submarine canyons represent an essential habitat network for krill hotspots in a Large Marine Ecosystem.

    Science.gov (United States)

    Santora, Jarrod A; Zeno, Ramona; Dorman, Jeffrey G; Sydeman, William J

    2018-05-15

    Submarine canyon systems are ubiquitous features of marine ecosystems, known to support high levels of biodiversity. Canyons may be important to benthic-pelagic ecosystem coupling, but their role in concentrating plankton and structuring pelagic communities is not well known. We hypothesize that at the scale of a large marine ecosystem, canyons provide a critical habitat network, which maintain energy flow and trophic interactions. We evaluate canyon characteristics relative to the distribution and abundance of krill, critically important prey in the California Current Ecosystem. Using a geological database, we conducted a census of canyon locations, evaluated their dimensions, and quantified functional relationships with krill hotspots (i.e., sites of persistently elevated abundance) derived from hydro-acoustic surveys. We found that 76% of krill hotspots occurred within and adjacent to canyons. Most krill hotspots were associated with large shelf-incising canyons. Krill hotspots and canyon dimensions displayed similar coherence as a function of latitude and indicate a potential regional habitat network. The latitudinal migration of many fish, seabirds and mammals may be enhanced by using this canyon-krill network to maintain foraging opportunities. Biogeographic assessments and predictions of krill and krill-predator distributions under climate change may be improved by accounting for canyons in habitat models.

  19. Neogene fallout tuffs from the Yellowstone hotspot in the Columbia Plateau region, Oregon, Washington and Idaho, USA.

    Directory of Open Access Journals (Sweden)

    Barbara P Nash

    Full Text Available Sedimentary sequences in the Columbia Plateau region of the Pacific Northwest ranging in age from 16-4 Ma contain fallout tuffs whose origins lie in volcanic centers of the Yellowstone hotspot in northwestern Nevada, eastern Oregon and the Snake River Plain in Idaho. Silicic volcanism began in the region contemporaneously with early eruptions of the Columbia River Basalt Group (CRBG, and the abundance of widespread fallout tuffs provides the opportunity to establish a tephrostratigrahic framework for the region. Sedimentary basins with volcaniclastic deposits also contain diverse assemblages of fauna and flora that were preserved during the Mid-Miocene Climatic Optimum, including Sucker Creek, Mascall, Latah, Virgin Valley and Trout Creek. Correlation of ashfall units establish that the lower Bully Creek Formation in eastern Oregon is contemporaneous with the Virgin Valley Formation, the Sucker Creek Formation, Oregon and Idaho, Trout Creek Formation, Oregon, and the Latah Formation in the Clearwater Embayment in Washington and Idaho. In addition, it can be established that the Trout Creek flora are younger than the Mascall and Latah flora. A tentative correlation of a fallout tuff from the Clarkia fossil beds, Idaho, with a pumice bed in the Bully Creek Formation places the remarkably well preserved Clarkia flora assemblage between the Mascall and Trout Creek flora. Large-volume supereruptions that originated between 11.8 and 10.1 Ma from the Bruneau-Jarbidge and Twin Falls volcanic centers of the Yellowstone hotspot in the central Snake River Plain deposited voluminous fallout tuffs in the Ellensberg Formation which forms sedimentary interbeds in the CRBG. These occurrences extend the known distribution of these fallout tuffs 500 km to the northwest of their source in the Snake River Plain. Heretofore, the distal products of these large eruptions had only been recognized to the east of their sources in the High Plains of Nebraska and Kansas.

  20. Mineralogy, geochemistry and low grade metamorphism of green tuffs of Karaj formation in Hesarbon area (south west Firoozkooh

    Directory of Open Access Journals (Sweden)

    Shiva Bahrami

    2017-03-01

    Full Text Available Green tuffs of middle Eocene age in Hesarbon area, south west of Firoozkuh (East of Central Alborz consist of a thick sequence of lithic-, crystal-,vitric-and calcareous-tuffs. Microscopic and x-ray diffraction studies show plagioclase (albite and oligoclase, alkali feldspar (sanidine, quartz, cristobalite, biotite and hornblende are the major minerals in the rocks studied. Secondary minerals such as analcime, chlorite, prehnite and clay minerals are mainly present in the groundmass of the rocks. Extensive tectonic activities have created a variety of structural features including numerous folds and faults and therefore, have caused the green tuffs to be crushed and converted to breccia tuffs in many parts. Veins and cavities are filled by considerable amounts of zeolitic minerals including heulandite group, clinoptilolite and natrolite along with calcite and secondary quartz. Based on geochemical data, they lie on the dacite and rhyodacite field showing a calc-alkaline nature in the corresponding diagrams. According to the chondrite and primitive mantle normalized diagrams of trace elements, negative anomalies of Eu, Nb, Ti, P and depletion of HFSE together with their position in the petrogenesis discrimination diagrams, it is most likely that these rocks are formed in the active continental margin of a subduction zone. The existence of analcime and prehnite in the groundmass demonstrate that these rocks have undergone some degrees of low-grade metamorphism due to the overburden of the layers in the temperature range 200-300 °C. The present study shows that zeolite minerals filling the fractures and cavities of tuffs are precipitated by hydrothermal fluids with a neutral pH to acidic

  1. Canyon formation constraints on the discharge of catastrophic outburst floods of Earth and Mars

    Science.gov (United States)

    Lapotre, Mathieu G. A.; Lamb, Michael P.; Williams, Rebecca M. E.

    2016-07-01

    Catastrophic outburst floods carved amphitheater-headed canyons on Earth and Mars, and the steep headwalls of these canyons suggest that some formed by upstream headwall propagation through waterfall erosion processes. Because topography evolves in concert with water flow during canyon erosion, we suggest that bedrock canyon morphology preserves hydraulic information about canyon-forming floods. In particular, we propose that for a canyon to form with a roughly uniform width by upstream headwall retreat, erosion must occur around the canyon head, but not along the sidewalls, such that canyon width is related to flood discharge. We develop a new theory for bedrock canyon formation by megafloods based on flow convergence of large outburst floods toward a horseshoe-shaped waterfall. The model is developed for waterfall erosion by rock toppling, a candidate erosion mechanism in well fractured rock, like columnar basalt. We apply the model to 14 terrestrial (Channeled Scablands, Washington; Snake River Plain, Idaho; and Ásbyrgi canyon, Iceland) and nine Martian (near Ares Vallis and Echus Chasma) bedrock canyons and show that predicted flood discharges are nearly 3 orders of magnitude less than previously estimated, and predicted flood durations are longer than previously estimated, from less than a day to a few months. Results also show a positive correlation between flood discharge per unit width and canyon width, which supports our hypothesis that canyon width is set in part by flood discharge. Despite lower discharges than previously estimated, the flood volumes remain large enough for individual outburst floods to have perturbed the global hydrology of Mars.

  2. Stratigraphic relations and hydrologic properties of the Paintbrush Tuff (PTn) hydrologic unit, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Moyer, T.C.; Geslin, J.K.; Flint, L.E.

    1996-01-01

    Yucca Mountain is being investigated as a potential site for a high- level nuclear waste repository. The intent of this study was to clarify stratigraphic relations within the Paintbrush Tuff (PTn) unit at Yucca Mountain in order to better understand vertical and lateral variations in hydrologic properties as they relate to the lithologic character of these rocks. This report defines informal stratigraphic units within the PTn interval, demonstrates their lateral continuity in the Yucca Mountain region, describes later and vertical variations within them, and characterizes their hydrologic properties and importance to numerical flow and transport models. We present tables summarizing the depth to stratigraphic contacts in cored borehole studies, and unit descriptions and correlations in 10 measured sections

  3. In situ changes in the moisture content of heated, welded tuff based on thermal neutron measurements

    International Nuclear Information System (INIS)

    Ramirez, A.L.; Carlson, R.C.; Buscheck, T.A.

    1991-07-01

    Thermal neutron logs were collected to monitor changes in moisture content within a welded tuff rock mass heated from a borehole containing an electrical heater which remained energized for 195 days. Thermal neutron measurements were made in sampling boreholes before, during and after heating. The results generally corroborated our conceptual understanding of hydrothermal flow as well as most of the numerical modeling conducting for this study. Conceptual models have been developed in conjunction with the numerical model calculations to explain differences in the drying and re-wetting behavior above and below the heater. Numerical modeling indicated that the re-wetting of the dried-out zone was dominated by the binary diffusion of water vapor through fractures. Saturation gradients in the rock matrix resulted in relative humidity gradients which drove water vapor (primarily along fractures) back to the dried-out zone where it condensed along the fracture walls and was imbibed by the matrix. 4 refs., 28 figs

  4. Estimates of secondary waste production from operations at a proespective geologic repository in tuff

    International Nuclear Information System (INIS)

    Engelhard, M.P.; Jardine, L.J.

    1985-01-01

    In this paper, a method is outlined for estimating the volumes of solid and liquid radioactive wastes produced during the operation of a repository in tuff. Volume estimates were also developed based on a preliminary conceptual facility design. Based on a disposal rate of 3000 MTU/y of commercial spent fuel, the waste estimates ranged from 793 to 2464 m 3 /y of uncompacted solids and from 80,431 to 128,690 L/y of liquids, depending on the specific set of facility features assumed. The estimates of waste quantities were most dependent on variations in the ratio of truck to rail cask shipments received. The quantities of waste generated on site decreased as this ratio decreased. Although there are large uncertainties in the current estimates caused by the preliminary nature of the facility designs and the limited amount of engineering detail completed, the methodology can be used to refine estimates as the repository design progresses

  5. Geotechnical instrumentation requirements for at-depth testing and repository monitoring in tuff

    International Nuclear Information System (INIS)

    Zimmerman, R.M.

    1982-01-01

    Minimum required geotechnical measurements for confirmation of repository performance include thermal and thermomechanical responses; changes in stress, strain, and displacements; and pore pressure and groundwater flow characteristics. Conditions expected in tuff are: maximum rock temperatures of less than 250 0 C, stresses less than 100 MPa, strains between +-0.01 mm/mm, and pore pressures less than 35 KPa in the unsaturated zone where hydraulic head is not the primary contributor. The paper describes instrumentation needed to make the desired measurements. In general, the instrumentation and data system are required to be stable and reliable for tens of years. Designs must consider requirements for temperature stability, temperature expansion compensation, moisture resistance, and long-term durability in mining-type environments. Severe requirements such as these suggest consideration of techniques for in-situ replacement of instrumentation. State-of-the-art instrumentation is briefly described along with a discussion of needs for refinement, replacement/recalibration and instrumentation development

  6. Bulk and mechanical properties of the Paintbrush tuff recovered from borehole USW NRG-6: Data report

    International Nuclear Information System (INIS)

    Martin, R.J.; Boyd, P.J.; Noel, J.S.; Price, R.H.

    1994-11-01

    Experimental results are presented for bulk and mechanical properties measurements on specimens of the Paintbrush tuff recovered from borehole USW NRG-6 at Yucca Mountain, Nevada. Measurements have been performed on four thermal/mechanical units, TCw, PTn, TSw1 and TSw2. On each specimen the following bulk properties have been reported: dry bulk density, saturated bulk density, average grain density, and porosity. Unconfined compression to failure, confined compression to failure, and indirect tensile strength tests were performed on selected specimens recovered from the borehole. In addition, compressional and shear wave velocities were measured on specimens designated for unconfined compression and confined compression experiments. Measurements were conducted at room temperature on nominally water saturated specimens; however, some specimens of PTn were tested in a room dry condition. The nominal strain rate for the fracture experiments was 10 -5 s -1

  7. Microstructural Analyses of Topopah Spring Tuff from the Large Block Test at Fran Ridge, Nevada

    International Nuclear Information System (INIS)

    Roberts, J.J.

    2000-01-01

    Microstructural information (e.g., porosity, pore size distribution, and surface area) of porous media is critical to understanding water transport mechanisms and physical properties and their bearing on geophysical measurements. We report microstructural data obtained by mercury injection porosimetry (MIP) on 33 samples of densely welded Topopah Spring tuff from Fran Ridge, Yucca Mountain, Nevada Test Site (NTS), Nevada. The characterization of these samples is also important for the interpretation and analysis of the Large Block Test (LBT) performed in support of the Yucca Mountain Project (YMP). This report includes previously published data on samples from the same location (Roberts and Lin, 1996). We also present information from the Yucca Mountain Site Characterization Project/Lawrence Livermore National Laboratory (YMSCP/LLNL) Large Block Test Engineering Plan (Wilder, 1995) to allow correlation of our data directly to various planes within the Large Block

  8. The sorption of uranium and technetium on bentonite, tuff and granodiorite

    International Nuclear Information System (INIS)

    Baston, G.M.N.; Berry, J.A.; Brownsword, M.; Cowper, M.M.; Heath, T.G.; Tweed, C.J.

    1995-01-01

    A combined experimental and modeling study of the sorption of uranium and technetium on geological materials has been carried out as part of the PNC program to increase confidence in the performance assessment for a high-level radioactive waste (HLW) repository in Japan. Batch sorption experiments have been performed in order to study the sorption of uranium and technetium onto bentonite, tuff and granodiorite from both equilibrated seawater and de-ionized water under strongly-reducing and non-reducing conditions. A preliminary study of the sorption of uranium on mineral surfaces in granodiorite has also been undertaken using a nuclear microprobe. Mathematical modeling using the geochemical speciation program HARPHRQ in conjunction with the HATCHES database has been carried out in order to interpret the results of the sorption experiments

  9. Stratigraphic relations and hydrologic properties of the Paintbrush Tuff (PTn) hydrologic unit, Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, T.C.; Geslin, J.K. [Science Applications International Corp., Golden, CO (United States); Flint, L.E. [U.S. Geological Survey, Yucca Mountain Project, Mercury, NV (United States)

    1996-08-01

    Yucca Mountain is being investigated as a potential site for a high- level nuclear waste repository. The intent of this study was to clarify stratigraphic relations within the Paintbrush Tuff (PTn) unit at Yucca Mountain in order to better understand vertical and lateral variations in hydrologic properties as they relate to the lithologic character of these rocks. This report defines informal stratigraphic units within the PTn interval, demonstrates their lateral continuity in the Yucca Mountain region, describes later and vertical variations within them, and characterizes their hydrologic properties and importance to numerical flow and transport models. We present tables summarizing the depth to stratigraphic contacts in cored borehole studies, and unit descriptions and correlations in 10 measured sections.

  10. Effects of elevated temperature and pore pressure on the mechanical behavior of Bullfrog tuff

    International Nuclear Information System (INIS)

    Olsson, W.A.

    1982-02-01

    Samples of the Bullfrog Member of the Crater Flat Tuff from the depth interval 758.9 to 759.2 m in hole USW-G1 on the Nevada Test Site were tested in triaxial compression. Test conditions were: (1) effective confining pressure to 20 MPa; (2) temperature of 200 0 C; (3) both dry and with pore water pressures from 3.4 to 5 MPa; and (4) a strain-rate of 10 -4 /s. The results suggest that the presence of water causes the strength to decrease. In addition, the brittle-ductile transition pressure for this rock was found to be about 15 MPa, regardless of saturation. Below this pressure deformation is characterized by unstable stress drops and the development of a single fracture, and above this pressure deformation is stable and distributed more uniformly throughout the sample

  11. Marine litter in submarine canyons of the Bay of Biscay

    Science.gov (United States)

    van den Beld, Inge M. J.; Guillaumont, Brigitte; Menot, Lénaïck; Bayle, Christophe; Arnaud-Haond, Sophie; Bourillet, Jean-François

    2017-11-01

    Marine litter is a matter of increasing concern worldwide, from shallow seas to the open ocean and from beaches to the deep-seafloor. Indeed, the deep sea may be the ultimate repository of a large proportion of litter in the ocean. We used footage acquired with a Remotely Operated Vehicle (ROV) and a towed camera to investigate the distribution and composition of litter in the submarine canyons of the Bay of Biscay. This bay contains many submarine canyons housing Vulnerable Marine Ecosystems (VMEs) such as scleractinian coral habitats. VMEs are considered to be important for fish and they increase the local biodiversity. The objectives of the study were to investigate and discuss: (i) litter density, (ii) the principal sources of litter, (iii) the influence of environmental factors on the distribution of litter, and (iv) the impact of litter on benthic communities. Litter was found in all 15 canyons and at three sites on the edge of the continental shelf/canyon, in 25 of 29 dives. The Belle-île and Arcachon Canyons contained the largest amounts of litter, up to 12.6 and 9.5 items per 100 images respectively. Plastic items were the most abundant (42%), followed by fishing-related items (16%). The litter had both a maritime and a terrestrial origin. The main sources could be linked to fishing activities, major shipping lanes and river discharges. Litter appeared to accumulate at water depths of 801-1100 m and 1401-1700 m. In the deeper of these two depth ranges, litter accumulated on a geologically structured area, accounting for its high frequency at this depth. A larger number of images taken in areas of coral in the shallower of these two depth ranges may account for the high frequency of litter detection at this depth. A larger number of litter items, including plastic objects in particular, were observed on geological structures and in coral areas than on areas of bare substratum. The distribution of fishing-related items was similar for the various types of

  12. Paleotransport of lanthanides and strontium recorded in calcite compositions from tuffs at Yucca Mountain, Nevada, USA

    International Nuclear Information System (INIS)

    Vaniman, D.T.; Chipera, S.J.

    1996-01-01

    Secondary calcite occurs in both saturated and unsaturated hydrologic zones (SZ and UZ, respectively) in the tuffs at Yucca Mountain, Nevada, USA. In the upper UZ, the major constituents of the calcite crystal structure (C, O) have surface origins. At greater depth there is a open-quotes barren zone,close quotes straddling the water table, where calcite is rare and mixing of surface and subsurface sources may occur. Deep in the SZ, distinctive Mn calcites reflect deep sources, including Ca released as analcime or albite formed and carbonates derived from underlying Paleozoic rocks. In the UZ and in the barren zone, above the deep Mn calcites, variations in calcite lanthanide chemistry can be used to distinguish rhyolitic from quartz-latitic sources. Lanthanide ratios and Sr contents of calcites record the chemical evolution of waters flowing through the UZ and upper SZ. Variations in calcite chemistry in the UZ and in the barren zone show that (1) Sr, which is readily exchanged with clays or zeolites, is essentially removed from some flowpaths that are in contact with these minerals and (2) traces of Mn oxides found in the tuffs have a significant effect of groundwater chemistry in the UZ and in the barren zone by removing almost all Ce from solution (evidenced by characteristic Ce depletions in calcite throughout this zone). Extreme Ce removal may be a result of Ce oxidation (Ce 3+ → Ce 4+ ) at the surfaces of some Mn oxides, particularly rancieite. Higher Sr contents and lack of Ce depletions in the deeper Mn calcites reflect different ages, origins, and transport systems. The calcite record of lanthanide and Sr transport in the UZ shows that minor minerals (clays and zeolites) and even trace minerals (Mn oxides) will affect the compositions of groundwaters that flow over distances greater than a few tens of meters. 43 refs., 8 figs., 4 tabs

  13. Geochemical homogeneity of tuffs at the potential repository level, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Peterman, Zell E.; Cloke, Paul

    2001-01-01

    In a potential high-level radioactive waste repository at Yucca Mountain, Nevada, radioactive waste and canisters, drip shields protecting the waste from seepage and from rock falls, the backfill and invert material of crushed rock, the host rock, and water and gases contained within pores and fractures in the host rock together would form a complex system commonly referred to as the near-field geochemical environment. Materials introduced into the rock mass with the waste that are designed to prolong containment collectively are referred to as the Engineered Barrier System, and the host rock and its contained water and gases compose the natural system. The interaction of these component parts under highly perturbed conditions including temperatures well above natural ambient temperatures will need to be understood to assess the performance of the potential repository for long-term containment of nuclear waste. The geochemistry and mineralogy of the rock mass hosting the emplacement drifts must be known in order to assess the role of the natural system in the near-field environment. Emplacement drifts in a potential repository at Yucca Mountain would be constructed in the phenocryst-poor member of the Topopah Spring Tuff which is composed of both lithophysal and nonlithophysal zones. The chemical composition of the phenocryst-poor member has been characterized by numerous chemical analyses of outcrop samples and of core samples obtained by surface-based drilling. Those analyses have shown that the phenocryst-poor member of the Topopah Spring Tuff is remarkably uniform in composition both vertically and laterally. To verify this geochemical uniformity and to provide rock analyses of samples obtained directly from the potential repository block, major and trace elements were analyzed in core samples obtained from drill holes in the cross drift, which was driven to provide direct access to the rock mass where emplacement drifts would be constructed

  14. Fitful and protracted magma assembly leading to a giant eruption, Youngest Toba Tuff, Indonesia

    Science.gov (United States)

    Reid, Mary R; Vazquez, Jorge A.

    2017-01-01

    The paroxysmal eruption of the 74 ka Youngest Toba Tuff (YTT) of northern Sumatra produced an extraordinary 2800 km3 of non-welded to densely welded ignimbrite and co-ignimbrite ash-fall. We report insights into the duration of YTT magma assembly obtained from ion microprobe U-Th and U-Pb dates, including continuous age spectra over >50% of final zircon growth, for pumices and a welded tuff spanning the compositional range of the YTT. A relatively large subpopulation of zircon crystals nucleated before the penultimate caldera-related eruption at 501 ka, but most zircons yielded interior dates 100-300 ka thereafter. Zircon nucleation and growth was likely episodic and from diverse conditions over protracted time intervals of >100 to >500 ka. Final zircon growth is evident as thin rim plateaus that are in Th/U chemical equilibrium with hosts, and that give crystallization ages within tens of ka of eruption. The longevity and chemical characteristics of the YTT zircons, as well as evidence for intermittent zircon isolation and remobilization associated with magma recharge, is especially favored at the cool and wet eutectoid conditions that characterize at least half of the YTT, wherein heat fluxes could dissolve major phases but have only a minor effect on larger zircon crystals. Repeated magma recharge may have contributed to the development of compositional zoning in the YTT but, considered together with limited allanite, quartz, and other mineral dating and geospeedometry, regular perturbations to the magma reservoir over >400 ka did not lead to eruption until 74 ka ago.

  15. LITHOSTRATIGRAPHY AND SHEAR-WAVE VELOCITY IN THE CRYSTALLIZED TOPOPAH SPRING TUFF, YUCCA MOUNTAIN, NEVADA

    International Nuclear Information System (INIS)

    D. BUESCH; K.H. STOKOE; M. SCHUHEN

    2006-01-01

    Evaluation of the seismic response of the proposed spent nuclear fuel and high-level radioactive waste repository at Yucca Mountain, Nevada, is in part based on the seismic properties of the host rock, the 12.8-million-year-old Topopah Spring Tuff. Because of the processes that formed the tuff, the densely welded and crystallized part has three lithophysal and three nonlithophysal zones, and each zone has characteristic variations in lithostratigraphic features and structures of the rocks. Lithostratigraphic features include lithophysal cavities, rims on lithophysae and some fractures, spots (which are similar to rims but without an associated cavity or aperture), amounts of porosity resulting from welding, crystallization, and vapor-phase corrosion and mineralization, and fractures. Seismic properties, including shear-wave velocity (V s ), have been measured on 38 pieces of core, and there is a good ''first order'' correlation with the lithostratigraphic zones; for example, samples from nonlithophysal zones have larger V s values compared to samples from lithophysal zones. Some samples have V s values that are beyond the typical range for the lithostratigraphic zone; however, these samples typically have one or more fractures, ''large'' lithophysal cavities, or ''missing pieces'' relative to the sample size. Shear-wave velocity data measured in the tunnels have similar relations to lithophysal and nonlithophysal rocks; however, tunnel-based values are typically smaller than those measured in core resulting from increased lithophysae and fracturing effects. Variations in seismic properties such as V s data from small-scale samples (typical and ''flawed'' core) to larger scale traverses in the tunnels provide a basis for merging our understanding of the distributions of lithostratigraphic features (and zones) with a method to scale seismic properties

  16. Stratigraphy, sedimentology and eruptive mechanisms in the tuff cone of El Golfo (Lanzarote, Canary Islands)

    Science.gov (United States)

    Pedrazzi, Dario; Martí, Joan; Geyer, Adelina

    2013-07-01

    The tuff cone of El Golfo on the western coast of Lanzarote (Canary Islands) is a typical hydrovolcanic edifice. Along with other edifices of the same age, it was constructed along a fracture oriented NEE-SWW that coincides with the main structural trend of recent volcanism in this part of the island. We conducted a detailed stratigraphic study of the succession of deposits present in this tuff cone and here interpret them in light of the depositional processes and eruptive dynamics that we were able to infer. The eruptive sequence is represented by a succession of pyroclastic deposits, most of which were emplaced by flow, plus a number of air-fall deposits and ballistic blocks and bombs. We distinguished five different eruptive/depositional stages on the basis of differences in inferred current flow regimes and fragmentation efficiencies represented by the resulting deposits; the different stages may be related to variations in the explosive energy. Eight lithofacies were identified based on sedimentary discontinuities, grain size, components, variations in primary laminations and bedforms. The volcanic edifice was constructed very rapidly around the vent, and this is inferred to have controlled the amount of water that was able to enter the eruption conduit. The sedimentological characteristics of the deposits and the nature and distribution of palagonitic alteration suggest that most of the pyroclastic succession in El Golfo was deposited in a subaerial environment. This type of hydrovolcanic explosive activity is common in the coastal zones of Lanzarote and the other Canary Islands and is one of the main potential hazards that could threaten the human population of this archipelago. Detailed studies of these hydrovolcanic eruptions such as the one we present here can help volcanologists understand the hazards that this type of eruption can generate and provide essential information for undertaking risk assessment in similar volcanic environments.

  17. Canyon air flow measurement utilizing ASME standard pitot tube arrays

    International Nuclear Information System (INIS)

    Moncrief, B.R.

    1990-01-01

    The Savannah River Site produces nuclear materials for national defense. In addition to nuclear reactors, the site has separation facilities for reprocessing irradiated nuclear fuel. The chemical separation of highly radioactive materials takes place by remote control in large buildings called canyons. Personnel in these buildings are shielded from radiation by thick concrete walls. Contaminated air is exhausted from the canyons and contaminants are removed by sand filters prior to release to the atmosphere through a stack. When these facilities were built on a crash basis in the early 1950's, inadequate means were provided for pressure and air flow measurement. This presentation describes the challenge we faced in retrofitting a highly radioactive, heavily shielded facility with instrumentation to provide this capability

  18. Hydraulics of outburst floods spilling over a steep-walled canyon: Implications for paleo-discharges on Mars

    Science.gov (United States)

    Lapotre, Mathieu; Lamb, Michael

    2013-04-01

    Canyons carved by outburst floods are common landforms on Earth and Mars. These canyons are generally found in fractured basalts and jointed sedimentary rocks. Flood-carved canyons commonly have steep headwalls and a roughly constant width, and are often thought to have formed from upstream headwall propagation due to waterfall erosion. Because morphology is readily available from satellite imagery, these canyons offer a unique opportunity to quantify the discharge of rare, catastrophic paleo-floods on Earth and Mars. However, mechanistic relationships that relate canyon size to flood discharge have yet to be developed. We propose that the width of a canyon headwall in fractured rock is set by the spatial distribution of erosion around the rim of the canyon, which is controlled by the distribution of shear stresses induced by the overflowing water as it is focused into the canyon head. We test this hypothesis by performing a series of numerical simulations of flood-water focusing using ANUGA Hydro, a 2D-depth averaged, fully turbulent, hydraulic numerical modeling suite allowing for Froude-number transitions. The numerical simulations were designed to explore five dimensionless variables: the aspect ratio of the canyon (length normalized by width), the canyon width to flood-water width ratio, the canyon width to normal-flow depth ratio, the Froude number, and the topographic gradient upstream of the canyon. Preliminary results show that flow focusing leads to increased shear stresses at the canyon head compared to the sides of the canyon for subcritical floods and higher canyon aspect ratios. This suggests that proto-canyons start growing from a topographic defect in all directions until they reach a critical length for the side walls to dry. Once this critical length is attained, canyons focus most of the flood waters into their heads, and propagate upstream only, maintaining roughly constant widths. Preliminary results suggest that canyon width may be used to

  19. Geomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid-Atlantic continental margin

    Science.gov (United States)

    Obelcz, Jeffrey; Brothers, Daniel S.; Chaytor, Jason D.; ten Brink, Uri S.; Ross, Steve W.; Brooke, Sandra

    2013-01-01

    Shelf-sourced submarine canyons are common features of continental margins and are fundamental to deep-sea sedimentary systems. Despite their geomorphic and geologic significance, relatively few passive margin shelf-breaching canyons worldwide have been mapped using modern geophysical methods. Between 2007 and 2012 a series of geophysical surveys was conducted across four major canyons of the US Mid-Atlantic margin: Wilmington, Baltimore, Washington, and Norfolk canyons. More than 5700 km2 of high-resolution multibeam bathymetry and 890 line-km of sub-bottom CHIRP profiles were collected along the outer shelf and uppermost slope (depths of 80-1200 m). The data allowed us to compare and contrast the fine-scale morphology of each canyon system. The canyons have marked differences in the morphology and orientation of canyon heads, steepness and density of sidewall gullies, and the character of the continental shelf surrounding canyon rims. Down-canyon axial profiles for Washington, Baltimore and Wilmington canyons have linear shapes, and each canyon thalweg exhibits morphological evidence for recent, relatively small-scale sediment transport. For example, Washington Canyon displays extremely steep wall gradients and contains ~100 m wide, 5–10 m deep, v-shaped incisions down the canyon axis, suggesting modern or recent sediment transport. In contrast, the convex axial thalweg profile, the absence of thalweg incision, and evidence for sediment infilling at the canyon head, suggest that depositional processes strongly influence Norfolk Canyon during the current sea-level high-stand. The north walls of Wilmington, Washington and Norfolk canyons are steeper than the south walls due to differential erosion, though the underlying cause for this asymmetry is not clear. Furthermore, we speculate that most of the geomorphic features observed within the canyons (e.g., terraces, tributary canyons, gullies, and hanging valleys) were formed during the Pleistocene, and show only

  20. Study of line source characteristics for 2-D physical modelling of pollutant dispersion in street canyons

    Energy Technology Data Exchange (ETDEWEB)

    Meroney, Robert N. [Fluid Mechanics and Wind Engineering Program, Civil Engineering Department, Colorado State University Fort Collins, CO (United States); Pavageau, Michel; Rafailidis, Stilianos; Schatzmann, Michael [Meteorologisches Institut, Universitaet Hamburg, Hamburg (Germany)

    1996-08-01

    The University of Hamburg initiated a wind tunnel study of car exhaust dispersion from street canyons in an urban environment to investigate how pollution dispersion is affected by street geometry. Particular emphasis at the beginning of this work was put on the design of a line source to represent traffic exhaust. Pollution dispersion was studied in two dimensions (i.e., infinite-length streets were assumed). The case of an isolated street canyon in open country was examined first. The same street canyon geometry was subsequently studied in an urban environment, i.e., with additional canyons of similar geometry upstream and downstream of the test street. The dynamic and dispersion characteristics of the flow in the two cases were quite different. In the canyon amidst open country we observed better canyon ventilation than in the urban roughness case

  1. The timing of sediment transport down Monterey Submarine Canyon, offshore California

    DEFF Research Database (Denmark)

    Stevens, Thomas; Paull, C.K.; Ussler, W., III

    2014-01-01

    luminescence (OSL) ages of quartz sand deposits and accelerator mass spectrometry 14C ages measured on benthic foraminifera to examine the timing of sediment transport through the axial channel of Monterey Submarine Canyon and Fan, offshore California. The OSL ages date the timing of sediment entry...... dates with water depth provides evidence of mixing and temporary storage of sediment as it moves through the canyon system. The ages also indicate that the frequency of sediment transport events decreases with distance down the canyon channel system. The amalgamated sands near the canyon head yield OSL......While submarine canyons are the major conduits through which sediments are transported from the continents out into the deep sea, the time it takes for sediment to pass down through a submarine canyon system is poorly constrained. Here we report on the first study to couple optically stimulated...

  2. A simple model for calculating air pollution within street canyons

    Science.gov (United States)

    Venegas, Laura E.; Mazzeo, Nicolás A.; Dezzutti, Mariana C.

    2014-04-01

    This paper introduces the Semi-Empirical Urban Street (SEUS) model. SEUS is a simple mathematical model based on the scaling of air pollution concentration inside street canyons employing the emission rate, the width of the canyon, the dispersive velocity scale and the background concentration. Dispersive velocity scale depends on turbulent motions related to wind and traffic. The parameterisations of these turbulent motions include two dimensionless empirical parameters. Functional forms of these parameters have been obtained from full scale data measured in street canyons at four European cities. The sensitivity of SEUS model is studied analytically. Results show that relative errors in the evaluation of the two dimensionless empirical parameters have less influence on model uncertainties than uncertainties in other input variables. The model estimates NO2 concentrations using a simple photochemistry scheme. SEUS is applied to estimate NOx and NO2 hourly concentrations in an irregular and busy street canyon in the city of Buenos Aires. The statistical evaluation of results shows that there is a good agreement between estimated and observed hourly concentrations (e.g. fractional bias are -10.3% for NOx and +7.8% for NO2). The agreement between the estimated and observed values has also been analysed in terms of its dependence on wind speed and direction. The model shows a better performance for wind speeds >2 m s-1 than for lower wind speeds and for leeward situations than for others. No significant discrepancies have been found between the results of the proposed model and that of a widely used operational dispersion model (OSPM), both using the same input information.

  3. Canyon Creek: A late Pleistocene vertebrate locality in interior Alaska

    Science.gov (United States)

    Weber, Florence R.; Hamilton, Thomas D.; Hopkins, David M.; Repenning, Charles A.; Haas, Herbert

    1981-09-01

    The Canyon Creek vertebrate-fossil locality is an extensive road cut near Fairbanks that exposes sediments that range in age from early Wisconsin to late Holocene. Tanana River gravel at the base of the section evidently formed during the Delta Glaciation of the north-central Alaska Range. Younger layers and lenses of fluvial sand are interbedded with arkosic gravel from Canyon Creek that contains tephra as well as fossil bones of an interstadial fauna about 40,000 years old. Solifluction deposits containing ventifacts, wedge casts, and rodent burrows formed during a subsequent period of periglacial activity that took place during the maximum phase of Donnelly Glaciation about 25,000-17,000 years ago. Overlying sheets of eolian sand are separated by a 9500-year-old paleosol that may correlate with a phase of early Holocene spruce expansion through central Alaska. The Pleistocene fauna from Canyon Creek consists of rodents (indicated by burrows), Mammuthus primigenius (woolly mammoth), Equus lambei (Yukon wild ass), Camelops hesternus (western camel), Bison sp. cf. B. crassicornis (large-horned bison), Ovis sp. cf. O. dalli (mountain sheep), Canis sp. cf. C. lupus (wolf), Lepus sp. cf. L. othus or L. arcticus (tundra hare), and Rangifer sp. (caribou). This assemblage suggests an open landscape in which trees and tall shrubs were either absent or confined to sheltered and moist sites. Camelops evidently was present in eastern Beringia during the middle Wisconsin interstadial interval but may have disappeared during the following glacial episode. The stratigraphic section at Canyon Creek appears to demonstrate that the Delta Glaciation of the north-central Alaska Range is at least in part of early Wisconsin age and was separated from the succeeding Donnelly Glaciation by an interstadial rather than interglacial episode.

  4. The down canyon evolution of submarine sediment density flows

    Science.gov (United States)

    Parsons, D. R.; Barry, J.; Clare, M. A.; Cartigny, M.; Chaffey, M. R.; Gales, J. A.; Gwiazda, R.; Maier, K. L.; McGann, M.; Paull, C. K.; O'Reilly, T. C.; Rosenberger, K. J.; Simmons, S.; Sumner, E. J.; Talling, P.; Xu, J.

    2017-12-01

    Submarine density flows, known as turbidity currents, transfer globally significant volumes of terrestrial and shelf sediments, organic carbon, nutrients and fresher-water into the deep ocean. Understanding such flows has wide implications for global organic carbon cycling, the functioning of deep-sea ecosystems, seabed infrastructure hazard assessments, and interpreting geological archives of Earth history. Only river systems transport comparable volumes of sediment over such large areas of the globe. Despite their clear importance, there are remarkably few direct measurements of these oceanic turbidity currents in action. Here we present results from the multi-institution Coordinated Canyon Experiment (CCE) which deployed multiple moorings along the axis of Monterey Canyon (offshore California). An array of six moorings, with downward looking acoustic Doppler current profilers (ADCP) were positioned along the canyon axis from 290 m to 1850 m water depth. The ADCPs reveal the internal flow structure of submarine density flows at each site. We use a novel inversion method to reconstruct the suspended sediment concentration and flow stratification field during each event. Together the six moorings provide the first ever views of the internal structural evolution of turbidity current events as they evolve down system. Across the total 18-month period of deployment at least 15 submarine sediment density flows were measured with velocities up to 8.1 m/sec, with three of these flows extending 50 kms down the canyon beyond the 1850 m water depth mooring. We use these novel data to highlight the controls on ignition, interval structure and collapse of individual events and discuss the implications for the functioning and deposits produced by these enigmatic flows.

  5. Ventilation Processes in a Three-Dimensional Street Canyon

    Czech Academy of Sciences Publication Activity Database

    Nosek, Štěpán; Kukačka, L.; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

    2016-01-01

    Roč. 159, č. 2 (2016), s. 259-284 ISSN 0006-8314 R&D Projects: GA ČR GAP101/12/1554; GA ČR GA15-18964S Institutional support: RVO:61388998 Keywords : Coherent structures * line source * pollution flux measurements * street canyon * wind tunnel Subject RIV: BK - Fluid Dynamics Impact factor: 2.573, year: 2016

  6. LES of flow in the street canyon

    OpenAIRE

    Brechler Josef; Fuka Vladimír

    2012-01-01

    Results of computer simulation of flow over a series of street canyons are presented in this paper. The setup is adapted from an experimental study by [4] with two different shapes of buildings. The problem is simulated by an LES model CLMM (Charles University Large Eddy Microscale Model) and results are analysed using proper orthogonal decomposition and spectral analysis. The results in the channel (layout from the experiment) are compared with results with a free top boundary.

  7. LES of flow in the street canyon

    Directory of Open Access Journals (Sweden)

    Brechler Josef

    2012-04-01

    Full Text Available Results of computer simulation of flow over a series of street canyons are presented in this paper. The setup is adapted from an experimental study by [4] with two different shapes of buildings. The problem is simulated by an LES model CLMM (Charles University Large Eddy Microscale Model and results are analysed using proper orthogonal decomposition and spectral analysis. The results in the channel (layout from the experiment are compared with results with a free top boundary.

  8. Basic repository source term and data sheet report: Lavender Canyon

    International Nuclear Information System (INIS)

    1988-01-01

    This report is one of a series describing studies undertaken in support of the US Department of Energy Civilian Radioactive Waste Management (CRWM) Program. This study contains the derivation of values for environmental source terms and resources consumed for a CRWM repository. Estimates include heavy construction equipment; support equipment; shaft-sinking equipment; transportation equipment; and consumption of fuel, water, electricity, and natural gas. Data are presented for construction and operation at an assumed site in Lavender Canyon, Utah. 3 refs; 6 tabs

  9. Basic repository source term and data sheet report: Davis Canyon

    International Nuclear Information System (INIS)

    1988-01-01

    This report is one of series describing studies undertaken in support of the US Department of Energy Civilian Radioactive Waste Management (CRWM) Program. This study contains the derivation of values for environmental source terms and resources consumed for a CRWM repository. Estimates include heavy construction equipment; support equipment; shaft-sinking equipment; transportation equipment; and consumption of fuel, water electricity, and natural gas. Data are presented for construction and operation at an assumed site in Davis Canyon, Utah. 6 tabs

  10. Trees in urban street canyons and their impact on the dispersion of automobile exhausts

    OpenAIRE

    Gromke, Christof; Ruck, Bodo

    2007-01-01

    The aim of the present study is to clarify the influence of trees on the dispersion of automobile exhausts in urban street canyons. For this purpose, measurements have been performed with a small scale wind tunnel model of an idealized, isolated street canyon with model trees placed along the canyon center axis. Sulfur hexafluoride (SF6) was released from a line source embedded in the street surface, simulating vehicle exhaust emissions. The influence of various tree planting arrangements on ...

  11. THE INFLUENCE OF BUOYANCY ON FLOW AND POLLUTANT DISPERSION IN STREET CANYONS

    OpenAIRE

    Buccolieri, Riccardo; Pulvirenti, Beatrice; Di Sabatino, Silvana; Britter, Rex

    2008-01-01

    Abstract: In this paper, the effect of buoyancy on flow and pollutant dispersion within street canyons is studied by means of computational fluid dynamics simulations. We consider a neutral boundary layer approaching a 3D street canyon assuming a wind direction perpendicular to the street canyon. The Boussinesq hypothesis for incompressible fluids is chosen for modelling buoyancy. We distinguish three cases: leeward, ground and windward wall heating. Thermal effects on both the flow ...

  12. Partly standing internal tides in a dendritic submarine canyon observed by an ocean glider

    Science.gov (United States)

    Hall, Rob A.; Aslam, Tahmeena; Huvenne, Veerle A. I.

    2017-08-01

    An autonomous ocean glider is used to make the first direct measurements of internal tides within Whittard Canyon, a large, dendritic submarine canyon system that incises the Celtic Sea continental slope and a site of high benthic biodiversity. This is the first time a glider has been used for targeted observations of internal tides in a submarine canyon. Vertical isopycnal displacement observations at different stations fit a one-dimensional model of partly standing semidiurnal internal tides - comprised of a major, incident wave propagating up the canyon limbs and a minor wave reflected back down-canyon by steep, supercritical bathymetry near the canyon heads. The up-canyon internal tide energy flux in the primary study limb decreases from 9.2 to 2.0 kW m-1 over 28 km (a dissipation rate of 1 - 2.5 ×10-7 Wkg-1), comparable to elevated energy fluxes and internal tide driven mixing measured in other canyon systems. Within Whittard Canyon, enhanced mixing is inferred from collapsed temperature-salinity curves and weakened dissolved oxygen concentration gradients near the canyon heads. It has previously been hypothesised that internal tides impact benthic fauna through elevated near-bottom current velocities and particle resuspension. In support of this, we infer order 20 cm s-1 near-bottom current velocities in the canyon and observe high concentrations of suspended particulate matter. The glider observations are also used to estimate a 1 °C temperature range and 12 μmol kg-1 dissolved oxygen concentration range, experienced twice a day by organisms on the canyon walls, due to the presence of internal tides. This study highlights how a well-designed glider mission, incorporating a series of tide-resolving stations at key locations, can be used to understand internal tide dynamics in a region of complex topography, a sampling strategy that is applicable to continental shelves and slopes worldwide.

  13. Evolution and Submarine Landslide Potential of Monterey Canyon Head, Offshore Central California

    Science.gov (United States)

    Maier, K. L.; Johnson, S. Y.; Hart, P. E.; Hartwell, S. R.

    2016-12-01

    Monterey Canyon, offshore central California, incises the shelf from near the shoreline to 30 km seaward where axial water depths approach 2,000 m. It is one of the world's most studied submarine canyons, yet debate continues concerning its age, formation, and associated geologic hazards. To address these issues, the USGS, with partial support from the California Seafloor Mapping Program, collected hundreds of kilometers of high-resolution, mini-sparker, single-channel (2009 and 2011 surveys) and multichannel (2015 survey) seismic-reflection profiles near the canyon head. The seismic data were combined with multibeam bathymetry to generate a geologic map of the proximal canyon, which delineates numerous faults and compound submarine landslide headwall scarps (covering up to 4 km2) along canyon walls. Seismic-reflection data reveal a massive ( 100 km2 lateral extent) paleochannel cut-and-fill complex underlying the proximal canyon. These subsurface cut-and-fill deposits span both sides of the relatively narrow modern canyon head, crop out in canyon walls, and incise into Purisima Formation (late Miocene and Pliocene) bedrock to depths of up to 0.3 s two-way travel time ( 240 m) below the modern shelf. We propose that the paleochannel complex represents previous locations of a migrating canyon head, and attribute its origin to multiple alternating cycles of fluvial and submarine canyon erosion and deposition linked to fluctuating sea levels. Thus, the canyon head imaged in modern bathymetry is a relatively young feature, perhaps forming in the last 20,000 years of sea-level rise. The paleocanyon deposits are significantly less consolidated than bedrock in deeper canyon walls, and therefore, are probably more prone to submarine landsliding. Nearby mapped faults occur within the active, distributed, San Andreas fault system, and earthquake-generated strong ground motions are likely triggers for past and future submarine landslides and potential associated tsunamis.

  14. Human rhinovirus capsid dynamics is controlled by canyon flexibility

    International Nuclear Information System (INIS)

    Reisdorph, Nichole; Thomas, John J.; Katpally, Umesh; Chase, Elaine; Harris, Ken; Siuzdak, Gary; Smith, Thomas J.

    2003-01-01

    Quantitative enzyme accessibility experiments using nano liquid chromatography electrospray mass spectrometry combined with limited proteolysis and isotope-labeling was used to examine the dynamic nature of the human rhinovirus (HRV) capsid in the presence of three antiviral compounds, a neutralizing Fab, and drug binding cavity mutations. Using these methods, it was found that the antivirals WIN 52084 and picovir (pleconaril) stabilized the capsid, while dansylaziridine caused destabilization. Site-directed mutations in the drug-binding cavity were found to stabilize the HRV14 capsid against proteolytic digestion in a manner similar to WIN 52084 and pleconaril. Antibodies that bind to the NIm-IA antigenic site and penetrate the canyon were also observed to protect the virion against proteolytic cleavage. These results demonstrate that quantifying the effects of antiviral ligands on protein 'breathing' can be used to compare their mode of action and efficacy. In this case, it is apparent that hydrophobic antiviral agents, antibodies, or mutations in the canyon region block viral breathing. Therefore, these studies demonstrate that mobility in the canyon region is a major determinant in capsid breathing

  15. The Influence of Roof Material on Diurnal Urban Canyon Breathing

    Science.gov (United States)

    Abuhegazy, Mohamed; Yaghoobian, Neda

    2017-11-01

    Improvements in building energy use, air quality in urban canyons and in general urban microclimates require understanding the complex interaction between urban morphology, materials, climate, and inflow conditions. Review of the literature indicates that despite a long history of valuable urban microclimate studies, more comprehensive approaches are needed to address energy, and heat and flow transport in urban areas. In this study, a more comprehensive simulation of the diurnally varying street canyon flow and associated heat transport is numerically investigated, using Large-eddy Simulation (LES). We use computational modeling to examine the impact of diurnal variation of the heat fluxes from urban surfaces on the air flow and temperature distribution in street canyons with a focus on the role of roof materials and their temperature footprints. A detailed building energy model with a three-dimensional raster-type geometry provides urban surface heat fluxes as thermal boundary conditions for the LES to determine the key aero-thermodynamic factors that affect urban street ventilation.

  16. Aquatic macroinvertebrates and water quality in Sandia Canyon

    International Nuclear Information System (INIS)

    Bennett, K.

    1994-05-01

    In 1990, field studies of water quality and stream macroinvertebrate communities were initiated in Sandia Canyon at Los Alamos National Laboratory. The studies were designed to establish baseline data and to determine the effects of routine discharges of industrial and sanitary waste. Water quality measurements were taken and aquatic macroinvertebrates sampled at three permanent stations within the canyon. Two of the three sample stations are located where the stream regularly receives industrial and sanitary waste effluents. These stations exhibited a low diversity of macroinvertebrates and slightly degraded water quality. The last sample station, located approximately 0.4 km (0.25 mi) downstream from the nearest wastewater outfall, appears to be in a zone of recovery where water quality parameters more closely resemble those found in natural streams in the Los Alamos area. A large increase in macroinvertebrate diversity was also observed at the third station. These results indicate that effluents discharged into Sandia Canyon have a marked effect on water quality and aquatic macroinvertebrate communities

  17. Late Holocene earthquake history of the Brigham City segment of the Wasatch fault zone at the Hansen Canyon, Kotter Canyon, and Pearsons Canyon trench sites, Box Elder County, Utah

    Science.gov (United States)

    DuRoss, Christopher B.; Personius, Stephen F.; Crone, Anthony J.; McDonald, Greg N.; Briggs, Richard W.

    2012-01-01

    Of the five central segments of the Wasatch fault zone (WFZ) having evidence of recurrent Holocene surface-faulting earthquakes, the Brigham City segment (BCS) has the longest elapsed time since its most recent surface-faulting event (~2.1 kyr) compared to its mean recurrence time between events (~1.3 kyr). Thus, the BCS has the highest time-dependent earthquake probability of the central WFZ. We excavated trenches at three sites––the Kotter Canyon and Hansen Canyon sites on the north-central BCS and Pearsons Canyon site on the southern BCS––to determine whether a surface-faulting earthquake younger than 2.1 ka occurred on the BCS. Paleoseismic data for Hansen Canyon and Kotter Canyon confirm that the youngest earthquake on the north-central BCS occurred before 2 ka, consistent with previous north-central BCS investigations at Bowden Canyon and Box Elder Canyon. At Hansen Canyon, the most recent earthquake is constrained to 2.1–4.2 ka and had 0.6–2.5 m of vertical displacement. At Kotter Canyon, we found evidence for two events at 2.5 ± 0.3 ka and 3.5 ± 0.3 ka, with an average displacement per event of 1.9–2.3 m. Paleoseismic data from Pearsons Canyon, on the previously unstudied southern BCS, indicate that a post-2 ka earthquake ruptured this part of the segment. The Pearsons Canyon earthquake occurred at 1.2 ± 0.04 ka and had 0.1–0.8 m of vertical displacement, consistent with our observation of continuous, youthful scarps on the southern 9 km of the BCS having 1–2 m of late Holocene(?) surface offset. The 1.2-ka earthquake on the southern BCS likely represents rupture across the Weber–Brigham City segment boundary from the penultimate Weber-segment earthquake at about 1.1 ka. The Pearsons Canyon data result in a revised length of the BCS that has not ruptured since 2 ka (with time-dependent probability implications), and provide compelling evidence of at least one segment-boundary failure and multi-segment rupture on the central WFZ. Our

  18. Characteristics of flow and reactive pollutant dispersion in urban street canyons

    Science.gov (United States)

    Park, Soo-Jin; Kim, Jae-Jin; Kim, Minjoong J.; Park, Rokjin J.; Cheong, Hyeong-Bin

    2015-05-01

    In this study, the effects of aspect ratio defined as the ratio of building height to street width on the dispersion of reactive pollutants in street canyons were investigated using a coupled CFD-chemistry model. Flow characteristics for different aspect ratios were analyzed first. For each aspect ratio, six emission scenarios with different VOC-NOX ratios were considered. One vortex was generated when the aspect ratio was less than 1.6 (shallow street canyon). When the aspect ratio was greater than 1.6 (deep street canyon), two vortices were formed in the street canyons. Comparing to previous studies on two-dimensional street canyons, the vortex center is slanted toward the upwind building and reverse and downward flows are dominant in street canyons. Near the street bottom, there is a marked difference in flow pattern between in shallow and deep street canyons. Near the street bottom, reverse and downward flows are dominant in shallow street canyon and flow convergence exists near the center of the deep street canyons, which induces a large difference in the NOX and O3 dispersion patterns in the street canyons. NOX concentrations are high near the street bottom and decreases with height. The O3 concentrations are low at high NO concentrations near the street bottom because of NO titration. At a low VOC-NOX ratio, the NO concentrations are sufficiently high to destroy large amount of O3 by titration, resulting in an O3 concentration in the street canyon much lower than the background concentration. At high VOC-NOX ratios, a small amount of O3 is destroyed by NO titration in the lower layer of the street canyons. However, in the upper layer, O3 is formed through the photolysis of NO2 by VOC degradation reactions. As the aspect ratio increases, NOX (O3) concentrations averaged over the street canyons decrease (increase) in the shallow street canyons. This is because outward flow becomes strong and NOX flux toward the outsides of the street canyons increases

  19. Influence of cetane improvers on the air quality in an urban street canyon

    International Nuclear Information System (INIS)

    Huang, H.; Akutsu, Y.; Arai, M.; Tamura, M.

    2000-01-01

    The concentration distributions of NO x , PM, HC and CO in an urban street canyon have been estimated using a two-dimensional air quality numerical model based on the k-e turbulent model and the atmospheric convection diffusion equation when various cetane improvers were used in diesel fuels. A wind vortex can be found within the street canyon, and the pollutants emitted from the bottom of the street canyon tend to follow the course of the wind field, moving circularly. The addition of cetane improvers can improve the air quality in a street canyon, all of the pollutants were found to decrease with increasing cetane number. (Author)

  20. UV Radiation in an Urban Canyon in Southeast Queensland

    Science.gov (United States)

    McKinley, A. R.; Moore, M. R.; Kimlin, M. G.

    2006-12-01

    Ultraviolet radiation (UV) has the possibility to both harm and to benefit human beings when unprotected exposure occurs. After receiving small amounts of UV our bodies begin to synthesise vitamin D, which is essential for maintaining healthy bones, however excessive UV exposure can result in a variety of damaging outcomes ranging from sunburn to skin cancer and cataracts. For this reason it is very important to understand the different environments in which people encounter UV so as to better prepare the public to make smart and healthy sun exposure decisions. Each day more and more people are moving into large cities around the world and spending their time inside the urban canyon, however UV measurements are generally taken at scientific stations in open areas or on top of tall buildings, meaning that at times the environmental characteristics measured may not accurately represent those found at street-level in these highly urbanized areas. Urban canyons are home to both very tall buildings and tropospheric air pollution, each of which reduces the amount of UV reaching street-level. This study measured the varying difference between UV measurements taken at street-level and at a standard UV monitoring site on top of a building outside of the urban canyon. Investigation was conducted in the central business district (CBD) of Brisbane, Australia, which models the CBDs of large cities around the world in that it boasts a great number of tall buildings, including many skyscrapers. Data was collected under clear sky conditions at five different street-level sites in the CBD (on either side of two streets running perpendicular to one another (four sites) and in a public square) and then compared to that obtained on the same day at the Queensland University of Technology's Australian Sun and Health Research Laboratory (ASHRL), which is located 2.5 kilometres outside Brisbane's CBD. Minimum erythemal dose (MED) data was collected at each location and it was found that

  1. Compilation of PRF Canyon Floor Pan Sample Analysis Results

    Energy Technology Data Exchange (ETDEWEB)

    Pool, Karl N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Minette, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wahl, Jon H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Greenwood, Lawrence R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Coffey, Deborah S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McNamara, Bruce K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bryan, Samuel A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Scheele, Randall D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Delegard, Calvin H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sinkov, Sergey I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Soderquist, Chuck Z. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fiskum, Sandra K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Brown, Garrett N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Clark, Richard A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-06-30

    On September 28, 2015, debris collected from the PRF (236-Z) canyon floor, Pan J, was observed to exhibit chemical reaction. The material had been transferred from the floor pan to a collection tray inside the canyon the previous Friday. Work in the canyon was stopped to allow Industrial Hygiene to perform monitoring of the material reaction. Canyon floor debris that had been sealed out was sequestered at the facility, a recovery plan was developed, and drum inspections were initiated to verify no additional reactions had occurred. On October 13, in-process drums containing other Pan J material were inspected and showed some indication of chemical reaction, limited to discoloration and degradation of inner plastic bags. All Pan J material was sealed back into the canyon and returned to collection trays. Based on the high airborne levels in the canyon during physical debris removal, ETGS (Encapsulation Technology Glycerin Solution) was used as a fogging/lock-down agent. On October 15, subject matter experts confirmed a reaction had occurred between nitrates (both Plutonium Nitrate and Aluminum Nitrate Nonahydrate (ANN) are present) in the Pan J material and the ETGS fixative used to lower airborne radioactivity levels during debris removal. Management stopped the use of fogging/lock-down agents containing glycerin on bulk materials, declared a Management Concern, and initiated the Potential Inadequacy in the Safety Analysis determination process. Additional drum inspections and laboratory analysis of both reacted and unreacted material are planned. This report compiles the results of many different sample analyses conducted by the Pacific Northwest National Laboratory on samples collected from the Plutonium Reclamation Facility (PRF) floor pans by the CH2MHill’s Plateau Remediation Company (CHPRC). Revision 1 added Appendix G that reports the results of the Gas Generation Rate and methodology. The scope of analyses requested by CHPRC includes the determination of

  2. Sorption and diffusion behavior of palladium in bentonite, granodiorite and tuff

    Energy Technology Data Exchange (ETDEWEB)

    Tachi, Yukio; Shibutani, Tomoki; Sato, Haruo [Radiochemistry Group, Waste Isolation Research Division, Waste Management and Fuel Cycle Research Center, Tokai Works, Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan); Shibata, Masahiro [Barrier Performance Group, Waste Isolation Research Division, Waste Management and Fuel Cycle Research Center, Tokai Works, Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan)

    1999-06-01

    Sorption and diffusion behavior palladium, which has been identified as one of the hazardous radionuclides in performance assessment of HLW disposal, in bentonite, granodiorite and tuff was studied in order to make reliable data set for the performance assessment. Sorption experiments of Pd on bentonite, granodiorite and tuff were conducted as functions of pH, ionic strength and liquid to solid ratio by batch method under aerobic conditions at room temperature. The distribution coefficients(K{sub d}) of Pd on these solids were almost in the range of 10{sup -1} to 10{sup 2} m{sup 3}/kg and were in the order of bentonite > granodiorite {approx_equal} tuff. The sorption trends with change in pH, ionic strength and liquid to solid ratio are very similar between three solids. The K{sub d} values were the highest pH 5 and decreased with increasing pH between 5 and 11. The effect of ionic strength on K{sub d} was not found in a range of 10{sup -2} to 10{sup -1}, but K{sub d} values increased with increasing liquid to solid ratio. The width of variation in K{sub d} was one order of magnitude in a liquid to solid ratio of 0.1 to 1 m{sup 3}/kg. Sorption behavior of Pd is different from that of divalent metal ions such as Ni and Co etc. and chemical analogy may be inappropriate. The dominant aqueous species of Pd in the experimental conditions studied is estimated to be neutral species, Pd(OH){sub 2}(aq) by the thermodynamic calculations. The K{sub d} values of Pd on three solids were relatively high and uncharged complexes may be more strongly sorbed. The pH dependency of K{sub d} values suggests that Pd sorption is most likely to be occurring onto positively charged S-OH{sub 2}{sup 2} type site which are progressively removed (to form SOH and SO{sup -} sites) at higher pH values. Diffusion behavior of Pd in bentonite was also studied by in-diffusion method as a function of dry density. The D{sub a} values obtained based on the instantaneous planar source model were in the

  3. Sorption and diffusion behavior of palladium in bentonite, granodiorite and tuff

    International Nuclear Information System (INIS)

    Tachi, Yukio; Shibutani, Tomoki; Sato, Haruo; Shibata, Masahiro

    1999-06-01

    Sorption and diffusion behavior palladium, which has been identified as one of the hazardous radionuclides in performance assessment of HLW disposal, in bentonite, granodiorite and tuff was studied in order to make reliable data set for the performance assessment. Sorption experiments of Pd on bentonite, granodiorite and tuff were conducted as functions of pH, ionic strength and liquid to solid ratio by batch method under aerobic conditions at room temperature. The distribution coefficients(K d ) of Pd on these solids were almost in the range of 10 -1 to 10 2 m 3 /kg and were in the order of bentonite > granodiorite ≅ tuff. The sorption trends with change in pH, ionic strength and liquid to solid ratio are very similar between three solids. The K d values were the highest pH 5 and decreased with increasing pH between 5 and 11. The effect of ionic strength on K d was not found in a range of 10 -2 to 10 -1 , but K d values increased with increasing liquid to solid ratio. The width of variation in K d was one order of magnitude in a liquid to solid ratio of 0.1 to 1 m 3 /kg. Sorption behavior of Pd is different from that of divalent metal ions such as Ni and Co etc. and chemical analogy may be inappropriate. The dominant aqueous species of Pd in the experimental conditions studied is estimated to be neutral species, Pd(OH) 2 (aq) by the thermodynamic calculations. The K d values of Pd on three solids were relatively high and uncharged complexes may be more strongly sorbed. The pH dependency of K d values suggests that Pd sorption is most likely to be occurring onto positively charged S-OH 2 2 type site which are progressively removed (to form SOH and SO - sites) at higher pH values. Diffusion behavior of Pd in bentonite was also studied by in-diffusion method as a function of dry density. The D a values obtained based on the instantaneous planar source model were in the orders of 10 -13 to 10 -12 m 2 /s and decreased with increasing dry density of bentonite. The K d

  4. Radionuclide sorption in Yucca Mountain tuffs with J-13 well water: Neptunium, uranium, and plutonium. Yucca Mountain site characterization program milestone 3338

    International Nuclear Information System (INIS)

    Triay, I.R.; Cotter, C.R.; Kraus, S.M.; Huddleston, M.H.

    1996-08-01

    We studied the retardation of actinides (neptunium, uranium, and plutonium) by sorption as a function of radionuclide concentration in water from Well J-13 and of tuffs from Yucca Mountain. Three major tuff types were examined: devitrified, vitric, and zeolitic. To identify the sorbing minerals in the tuffs, we conducted batch sorption experiments with pure mineral separates. These experiments were performed with water from Well J-13 (a sodium bicarbonate groundwater) under oxidizing conditions in the pH range from 7 to 8.5. The results indicate that all actinides studied sorb strongly to synthetic hematite and also that Np(V) and U(VI) do not sorb appreciably to devitrified or vitric tuffs, albite, or quartz. The sorption of neptunium onto clinoptilolite-rich tuffs and pure clinoptilolite can be fitted with a sorption distribution coefficient in the concentration range from 1 X 10 -7 to 3 X 10 -5 M. The sorption of uranium onto clinoptilolite-rich tuffs and pure clinoptilolite is not linear in the concentration range from 8 X 10 -8 to 1 X 10 -4 M, and it can be fitted with nonlinear isotherm models (such as the Langmuir or the Freundlich Isotherms). The sorption of neptunium and uranium onto clinoptilolite in J-13 well water increases with decreasing pH in the range from 7 to 8.5. The sorption of plutonium (initially in the Pu(V) oxidation state) onto tuffs and pure mineral separates in J-13 well water at pH 7 is significant. Plutonium sorption decreases as a function of tuff type in the order: zeolitic > vitric > devitrified; and as a function of mineralogy in the order: hematite > clinoptilolite > albite > quartz

  5. Effects of long-term exposure of tuffs to high-level nuclear waste-repository conditions. Preliminary report

    International Nuclear Information System (INIS)

    Blacic, J.; Carter, J.; Halleck, P.; Johnson, P.; Shankland, T.; Andersen, R.; Spicochi, K.; Heller, A.

    1982-02-01

    Tests have been performed to explore the effects of extended exposure of tuffs from the southwestern portion of the Nevada Test Site to temperatures and pressures similar to those that will be encountered in a high-level nuclear waste repository. Tuff samples ranging from highly welded, nonzeolitized to unwelded, highly zeolitized varieties were subjected to temperatures of 80, 120, and 180 0 C; confining pressures of 9.7 and 19.7 MPa; and water-pore pressures of 0.5 to 19.7 MPa for durations of 2 to 6 months. The following basic properties were measured before and after exposure and compared: tensile strength, uniaxial compressive strength, grain density, porosity, mineralogy, permeability, thermal expansion, and thermal conductivity. Depending on rock type and exposure conditions, significant changes in ambient tensile strength, compressive strength, grain density, and porosity were measured. Mineralogic examination, permeability, and thermal property measurements remain to be completed

  6. Study on the effect of Shahin-Dezh green Tuff on the mechanical characteristics of roller compact concrete

    Directory of Open Access Journals (Sweden)

    Sadegh Dardaei

    2016-12-01

    Full Text Available Due to the growing popularity of concrete structure and increasing use of them, especially Roller compacted concrete, applying Pozzolan and replacing cement with Pozzolan is very important. Nowadays, the use of the additive for cement replacement is common in RCC mix design due to its technical advantages and economic benefits as there is large quantity of Pozzolan mineral resources in Iran. In this paper the impact of produced concrete has been fully considered as well as the effect of this Pozzolan on the compressive strength, tensile strength and permeability by using green Tuff obtained from available Pozzolan in western Azarbaijan. The due results prove that Shahin-Dezh green Tuff improves concretes quality.

  7. Ages of tuff beds at East African early hominid sites and sediments in the Gulf of Aden

    Science.gov (United States)

    Sarna-Wojcicki, A. M.; Meyer, C.E.; Roth, P.H.; Brown, F.H.

    1985-01-01

    The early hominids of East Africa were dated by determining the ages of tuff beds at the sites. Despite much research using palaeomagnetic and K/Ar-dating techniques, some of those ages are still controversial 1,2. To obtain independent age estimates for these tephra layers, we have examined cores from DSDP Sites 231 and 232 in the Gulf of Aden (Fig. 1a) which consist mainly of calcareous nannofossil ooze, but also contain rare tephra horizons3 dated by interpolation from the established nannofossil stratigraphy (Fig. 1b). Chemical analysis confirms that the identity and sequence of these horizons is the same as that at the East African sites. We conclude that the age of the Tulu Bor Tuff is <3.4 Myr and hence that the Hadar hominid specimens are also

  8. Corrosion testing of a degraded moderator: L-Area Tuff Tanks

    International Nuclear Information System (INIS)

    Mickalonis, J.I.

    2000-01-01

    Based on test results, storage of the degraded moderator in 55-gallon 304L drums (0.065 inches thick) would not cause failure by general corrosion for up to 5 plus years storage. Acidic degraded moderator was temporarily stored in Tuff Tanks located in L-area. The moderator characteristics included a D 2 O content of 5.02--5.33%, a pH of 1.25--1.31, a conductivity of 29,300--31,200 m mhos/cm, tritium activity of 114--141 m Ci/mL, and levels of approximately 6,000 ppm for chloride and 500 ppm for chromium. The compatibility of the degraded with AISI Type 304L stainless steel (304L) was investigated in this study. Following ASTM standard practice, coupon immersion tests were conducted in both treated and untreated moderator. Treatment included the addition of either a 40 wt % NaOH solution, distilled water to serially dilute the chloride, or concentrated nitric acid to increase the nitrate concentration. Type 304L stainless steel exposed to the Tuff Tank moderator was found from these tests to: have a general corrosion rate of less than 5 mils per year (mpy) for 304L plate, which bounds that of the 304L storage drum, passivate at chloride concentrations up to 5,000 ppm for 304L sheet, resist corrosion for nitrate/chloride ratios ranging from 0.1 to 1,000, and be susceptible to crevice corrosion. Based on these test results, storage of the degraded moderator in 55-gallon 304L drums (0.065 inch thick) would not cause failure by general corrosion for up to 5+ years storage. The chloride concentration, [Cl], in the degraded moderator has been measured up to 6000 ppm. The potential or risk for aggressive localized attack of 304L increases with [Cl] concentration. A qualitative range is as follows: [Cl minus ] minus ] minus ] < 600 ppm, reasonable resistance, medium risk. The degraded moderator should be treated to reduce the chloride concentration to reduce the potential for localized corrosion and the risk for a leakage failure of the drum. A good practice would be to

  9. Scalar properties of transversely isotropic tuff from images of orthogonal cross sections

    International Nuclear Information System (INIS)

    Berge, P.A.; Berryman, J.G.; Blair, S.C.; Pena, C.

    1997-01-01

    Image processing methods have been used very effectively to estimate physical properties of isotropic porous earth materials such as sandstones. Anisotropic materials can also be analyzed in order to estimate their physical properties, but additional care and a larger number of well-chosen images of cross sections are required to obtain correct results. Although low-symmetry anisotropic media present difficulties for two-dimensional image processing methods, geologic materials are often transversely isotropic. Scalar properties of porous materials such as porosity and specific surface area can be determined with only minor changes in the analysis when the medium is transversely isotropic rather than isotropic. For example, in a rock that is transitively isotropic due to thin layers or beds, the overall porosity may be obtained by analyzing images of cross sections taken orthogonal to the bedding planes, whereas cross sections lying within the bedding planes will determine only the local porosity of the bed itself. It is known for translationally invariant anisotropic media that the overall specific surface area can be obtained from radial averages of the two-point correlation function in the full three-dimensional volume. Layered materials are not translationally invariant in the direction of the layering, but we show nevertheless how averages of cross sections may be used to obtain the specific surface area for a transversely isotropic rock. We report values of specific surface area obtained for thin sections of Topopah Spring Tuff from Yucca Mountain, Nevada. This formation is being evaluated as a potential host rock for geologic disposal of nuclear waste. Although the present work has made use of thin sections of tuff for the images, the same methods of analysis could also be used to simplify quantitative analysis of three-dimensional volumes of pore structure data obtained by means of x-ray microtomography or other methods, using only a few representative cross

  10. The one-dimensional compression method for extraction of pore water from unsaturated tuff and effects on pore-water chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Higgins, J.D.; Burger, P.A. [Colorado School of Mines, Golden, CO (United States); Yang, L.C. [Geological Survey, Denver, CO (United States)

    1997-12-31

    Study of the hydrologic system at Yucca Mountain, Nevada, requires extraction of pore-water samples from unsaturated tuff bedrock. Two generations of compression cells have been designed and tested for extracting representative, unaltered pore-water samples from unsaturated tuff cores. The one-dimensional compression cell has a maximum compressive stress rating of 552 MPa. Results from 86 tests show that the minimum degree of saturation for successful extraction of pore water was about 14% for non welded tuff and about 61% for densely welded tuff. The high-pressure, one-dimensional compression cell has a maximum compressive stress rating of 827 MPa. Results from 109 tests show that the minimum degree of saturation for successful extraction of pore water was about 7.5% for non welded tuff and about 34% for densely welded tuff. Geochemical analyses show that, in general, there is a decrease in ion concentration of pore waters as extraction pressures increase. Only small changes in pore-water composition occur during the one-dimensional extraction test.

  11. Thermal conductivity, bulk properties, and thermal stratigraphy of silicic tuffs from the upper portion of hole USW-G1, Yucca Mountain, Nye County, Nevada

    International Nuclear Information System (INIS)

    Lappin, A.R.; VanBuskirk, R.G.; Enniss, D.O.; Buters, S.W.; Prater, F.M.; Muller, C.B.; Bergosh, J.L.

    1982-03-01

    Thermal-conductivity and bulk-property measurements were made on welded and nonwelded silicic tuffs from the upper portion of Hole USW-G1, located near the southwestern margin of the Nevada Test Site. Bulk-property measurements were made by standard techniques. Thermal conductivities were measured at temperatures as high as 280 0 C, confining pressures to 10 MPa, and pore pressures to 1.5 MPa. Extrapolation of measured saturated conductivities to zero porosity suggests that matrix conductivity of both zeolitized and devitrified tuffs is independent of stratigraphic position, depth, and probably location. This fact allows development of a thermal-conductivity stratigraphy for the upper portion of Hole G1. Estimates of saturated conductivities of zeolitized nonwelded tuffs and devitrified tuffs below the water table appear most reliable. Estimated conductivities of saturated densely welded devitrified tuffs above the water table are less reliable, due to both internal complexity and limited data presently available. Estimation of conductivity of dewatered tuffs requires use of different air thermal conductivities in devitrified and zeolitized samples. Estimated effects of in-situ fracturing generally appear negligible

  12. Petrologic and geochemical characterization of the Bullfrog Member of the Crater Flat Tuff: outcrop samples used in waste package experiments

    International Nuclear Information System (INIS)

    Knauss, K.G.

    1983-09-01

    In support of the Waste Package Task within the Nevada Nuclear Waste Storage Investigation (NNWSI), experiments on hydrothermal rock/water interaction, corrosion, thermomechanics, and geochemical modeling calculations are being conducted. All of these activities require characterization of the initial bulk composition, mineralogy, and individual phase geochemistry of the potential repository host rock. This report summarizes the characterization done on samples of the Bullfrog Member of the Crater Flat Tuff (Tcfb) used for Waste Package experimental programs. 11 references, 17 figures, 3 tables

  13. New fission-track ages of mio-pliocene tuffs in the Sierras Pampeanas and Precordillera of Argentina

    International Nuclear Information System (INIS)

    Tabbutt, K.; Naeser, C.W.; Jordan, T.E.; Cerveny, P.F.

    1989-01-01

    Fission-track dates were determined for 18 volcanic tuff horizons located in nine Neogene foreland basin sequences distributed throughout the Precordillera and Sierras Pampeanas of Northwestern Argentina, an area of nearly horizontal subduction. These and other data indicate that a lower age limit for the sedimentary sequences studied is approximately 17 Ma. Therefore these fission-track dates constrain both the history of volcanic activity and the time of deposition in several foreland basins from the middle Miocene to Recent. Although the dates range from 3.6±0.8 Ma to 17.0±1.9 Ma, there is a marked increase in the number of ashes younger than 9 Ma. This implies that two distinct episodes of volcanic activity affected the region. The source of some of these tuffs is unknown but they are probably limited to the 'flat-slab' region between 27 deg and 32 deg S. Tuffs at Rio Blanco and Santa Florentina that are spatially associated with the Mogotes dacite domes of the Famatina Range represented magmatism bracketed from about 7 to 4 Ma in the region underlain by the flat-subducted plate. The stratigraphic relations in the basins show that the faulting that uplifted Sierra de Famatina was contemporaneous with the volcanism which reached the surface along the bounding faults. (Author) [es

  14. Characterization of crushed tuff for the evaluation of the fate of tracers in transport studies in the unsaturated zone

    International Nuclear Information System (INIS)

    Polzer, W.L.; Fuentes, H.R.; Raymond, R.; Bish, D.L.; Gladney, E.S.; Lopez, E.A.

    1987-03-01

    Results of field-scale (caisson) transport studies under unsaturated moisture and steady and nonsteady flow conditions indicate variability and a lack of conservation of mass in solute transport. The tuff materials used in that study were analyzed for the presence of tracers and of freshly precipitated material to help explain the variability and lack of conservation of mass. Selected tuff samples were characterized by neutron activation analysis for tracer identification, by x-ray diffraction for mineral identification, by petrographic analysis for identification of freshly precipitated material, and by x-ray fluorescence analysis for identification of major and trace elements. The results of these analyses indicate no obvious presence of freshly precipitated material that would retard tracer movement. The presence of the nonsorbing tracers (bromide and iodide) suggest the retention of these tracers in immobile water. The presence of the nonsorbing tracers (bromide and iodide) suggest the retention of these tracers in immobile water. The presence of sorbing and nonsorbing tracers on the tuff at some locations (even cesium at the 415-cm depth) and not at others suggests variability in transport. 15 refs., 14 figs., 9 tabs

  15. Removal and recovery of p-phenylenediamines developing compounds from photofinishing lab-washwater using clinoptilolite tuffs from Greece.

    Science.gov (United States)

    Vlessidis, A G; Triantafillidis, C S; Evmiridis, N P

    2001-04-01

    Clinoptilolite tuffs from areas in Thrace region of Greece are compared with synthetic zeolites NaY and NH4Y for the uptake of N4-ethyl-N4-(2-methansulphonamidoethyl)-2-methyl-1,4-phenylenediamin (sesquisulphate, monohydrate) with the trade name CD-3 for the purpose to be used for clean-up and recycling photo-finishing and photo-developing washwaters. The cation-exchange capacity is found to be 6.15-11.1 mg/g for zeoliferous tuffs at equilibrium concentration of 50 ppm CD-3 in aqueous solution compared to 65.0 mg/g of NaY and 48.2 mg/g for NH4Y synthetic zeolites corresponding to the removal of CD-3 from 120 to 2001 of 50 ppm aqueous solution per kg of natural zeoliferous tuff; this capacity is only 6-10 times lower than type-Y synthetic zeolite. Initial rates of uptake are 20.8 mg/l/min for natural and 38.5 mg/l/min for synthetic zeolites. Regeneration levels of 55, 23, 35, and 33% are obtained for MCH, SF, NaY, and NH4Y, respectively. The rapid and almost complete uptake of CD-3 from its aqueous solutions at low CD-3 concentrations by the natural zeolites is promising for such an application.

  16. Report on static hydrothermal alteration studies of Topopah Spring tuff waters in J-13 water at 150{sup 0}C

    Energy Technology Data Exchange (ETDEWEB)

    Knauss, K.G.; Beiriger, W.B.

    1984-08-31

    This report presents the results of preliminary experimental work done to define the package environment in a potential nuclear waste repository in the Topopah Spring Member of the Paintbrush Tuff. The work is supported by the Nevada Nuclear Waste Storage Investigations (NNWSI) Project as a part of the Waste Package task to design a package suitable for waste storage within volcanic units at the Nevada Test Site. Static hydrothermal alteration experiments were run for 4 months using polished wafers either fully submerged in an appropriate natural ground water or exposed to water-saturated air with enough excess water to allow refluxing. The aqueous results agreed favorably with similar experiments run using crushed tuff, and the use of solid polished wafers allowed us to directly evaluate the effects of reaction on the tuff. The results are preliminary in the sense that these experiments were run in Teflon-lined, static autoclaves, whereas subsequent experiments have been run in Dickson-type gold-cell rocking autoclaves. The results predict relatively minor changes in water chemistry, very minor alteration of the host rock, and the production of slight amounts of secondary minerals, when liquid water could return to the rock pores following the temperature maximum during the thermal period. 7 references, 16 figures, 10 tables.

  17. Geohydrology of volcanic tuff penetrated by test well UE-25b#1, Yucca Mountain, Nye County, Nevada

    Science.gov (United States)

    Lahoud, R.G.; Lobmeyer, D.H.; Whitfield, M.S.

    1984-01-01

    Test well UE-25bNo1, located on the east side of Yucca Mountain in the southwestern part of the Nevada Test Site, was drilled to a total depth of 1,220 meters and hydraulically tested as part of a program to evaluate the suitability of Yucca Mountain as a nuclear-waste repository. The well penetrated almost 46 meters of alluvium and 1,174 meters of Tertiary volcanic tuffs. The composite hydraulic head for aquifers penetrated by the well was 728.9 meters above sea level (471.4 meters below land surface) with a slight decrease in loss of hydraulic head with depth. Average hydraulic conductivities for stratigraphic units determined from pumping tests, borehole-flow surveys, and packer-injection tests ranged from less than 0.001 meter per day for the Tram Member of the Crater Flat Tuff to 1.1 meters per day for the Bullfrog Member of the Crater Flat Tuff. The small values represented matrix permeability of unfractured rock; the large values probably resulted from fracture permeability. Chemical analyses indicated that the water is a soft sodium bicarbonate type, slightly alkaline, with large concentrations of dissolved silica and sulfate. Uncorrected carbon-14 age dates of the water were 14,100 and 13,400 years. (USGS)

  18. PHYSIOLOGICAL REACTION OF THE SPECIES BRASSICA JUNCEA (L. CZERN. ON SALINIZED SOILS AMELIORATED WITH ZEOLITIC TUFF, PEAT AND PERLITE

    Directory of Open Access Journals (Sweden)

    Maria Cătălina PASTIA

    2017-12-01

    Full Text Available The physiological reaction of saline stress which Brassica juncea (L. Czern. plants undergo shows a greater growth and fresh substance gain process on previously cultivated soils that were fined with 20% zeolitic tuff and 5.09 g of neutral peat than the ones that had a substrate which hasn’t been cultivated on before that was fined with 5% zeolitic tuff and 1.39 g of perlite. The dry substance values obtained present a positive correlation with the values of fresh substance. Analysis of stomatal conductance enhances the hydric stress of plants which respond to saline stress with osmotic adjustment, accumulating high quantities of water comparing to the witness plant, which induces lower values of stomatal conductance and implicitly values are decreasing for photosynthesis, determining a low productivity. Higher values of stomatal conductance are reached at plants grown on previously cultivated soils fined with 20% zeolitic tuff and peat, and also at the ones grown on uncultivated soils fined with peat (29.45, respectively 30.05 mmol/m2/s.

  19. Feasibility assessment of copper-base waste package container materials in a tuff repository

    International Nuclear Information System (INIS)

    Acton, C.F.; McCright, R.D.

    1986-01-01

    This report discussed progress made during the second year of a two-year study on the feasibility of using copper or a copper-base alloy as a container material for a waste package in a potential repository in tuff rock at the Yucca Mountain site in Nevada. Corrosion testing in potentially corrosive irradiated environments received emphasis during the feasibility study. Results of experiments to evaluate the effect of a radiation field on the uniform corrosion rate of the copper-base materials in repository-relevant aqueous environments are given as well as results of an electrochemical study of the copper-base materials in normal and concentrated J-13 water. Results of tests on the irradiation of J-13 water and on the subsequent formation of hydrogen peroxide are given. A theoretical study was initiated to predict the long-term corrosion behavior of copper in the repository. Tests were conducted to determine whether copper would adversely affect release rates of radionuclides to the environment because of degradation of the Zircaloy cladding. A manufacturing survey to determine the feasibility of producing copper containers utilizing existing equipment and processes was completed. The cost and availability of copper was also evaluated and predicted to the year 2000. Results of this feasibility assessment are summarized

  20. Equilibrium sorption of cobalt, cesium, and strontium on Bandelier Tuff: analysis of alternative mathematical modeling

    International Nuclear Information System (INIS)

    Polzer, W.L.; Fuentes, H.R.; Essington, E.H.; Roensch, F.R.

    1985-01-01

    Sorption isotherms are derived from batch equilibrium data for cobalt, cesium and strontium on Bandelier Tuff. Experiments were conducted at an average temperature of 23 0 C and equilibrium was defined at 48 hours. The solute concentrations ranged from 0 to 500 mg/L. The radioactive isotopes 60 Co, 137 Cs, and 85 Sr were used to trace the sorption of the stable solutes. The Linear, Langmuir, Freundlich and a Modified Freundlich isotherm equations are evaluated. The Modified Freundlich isotherm equation is validated as a preferred general mathematical tool for representing the sorption of the three solutes. The empirical constants derived from the Modified Freundlich isotherm equation indicate that under dynamic flow conditions strontium will move most rapidly and cobalt least rapidly. On the other hand, chemical dispersion will be greatest for cesium and least for strontium. Hill Plots of the sorption data suggest that in the region of low saturation sorption of all three solutes is impeded by interactions among sorption sites; cobalt exhibits the greatest effect of interactions and strontium shows only a minimal effect. In the saturation region of 50% or more, sorption of cobalt is enhanced slightly by interactions among sorption sites whereas sorption of cesium and strontium appears to be independent of site interactions. 9 references, 4 figures, 2 tables

  1. On conditions and parameters important to model sensitivity for unsaturated flow through layered, fractured tuff

    International Nuclear Information System (INIS)

    Prindle, R.W.; Hopkins, P.L.

    1990-10-01

    The Hydrologic Code Intercomparison Project (HYDROCOIN) was formed to evaluate hydrogeologic models and computer codes and their use in performance assessment for high-level radioactive-waste repositories. This report describes the results of a study for HYDROCOIN of model sensitivity for isothermal, unsaturated flow through layered, fractured tuffs. We investigated both the types of flow behavior that dominate the performance measures and the conditions and model parameters that control flow behavior. We also examined the effect of different conceptual models and modeling approaches on our understanding of system behavior. The analyses included single- and multiple-parameter variations about base cases in one-dimensional steady and transient flow and in two-dimensional steady flow. The flow behavior is complex even for the highly simplified and constrained system modeled here. The response of the performance measures is both nonlinear and nonmonotonic. System behavior is dominated by abrupt transitions from matrix to fracture flow and by lateral diversion of flow. The observed behaviors are strongly influenced by the imposed boundary conditions and model constraints. Applied flux plays a critical role in determining the flow type but interacts strongly with the composite-conductivity curves of individual hydrologic units and with the stratigraphy. One-dimensional modeling yields conservative estimates of distributions of groundwater travel time only under very limited conditions. This study demonstrates that it is wrong to equate the shortest possible water-travel path with the fastest path from the repository to the water table. 20 refs., 234 figs., 10 tabs

  2. Estimation of hydraulic conductivities of Yucca Mountain tuffs from sorptivity and water retention measurements

    International Nuclear Information System (INIS)

    Zimmerman, R.W.; Bodvarsson, G.S.

    1995-06-01

    The hydraulic conductivity functions of the matrix rocks at Yucca Mountain, Nevada, are among the most important data needed as input for the site-scale hydrological model of the unsaturated zone. The difficult and time-consuming nature of hydraulic conductivity measurements renders it infeasible to directly measure this property on large numbers of cores. Water retention and sorptivity measurements, however, can be made relatively rapidly. The sorptivity is, in principle, a unique functional of the conductivity and water retention functions. It therefore should be possible to invert sorptivity and water retention measurements in order to estimate the conductivity; the porosity is the only other parameter that is required for this inversion. In this report two methods of carrying out this inversion are presented, and are tested against a limited data set that has been collected by Flint et al. at the USGS on a set of Yucca Mountain tuffs. The absolute permeability is usually predicted by both methods to within an average error of about 0.5 - 1.0 orders of magnitude. The discrepancy appears to be due to the fact that the water retention curves have only been measured during drainage, whereas the imbibition water retention curve is the one that is relevant to sorptivity measurements. Although the inversion methods also yield predictions of the relative permeability function, there are yet no unsaturated hydraulic conductivity data against which to test these predictions

  3. Mineralogic Zonation Within the Tuff Confining Unit, Yucca Flat, Nevada Test Site

    International Nuclear Information System (INIS)

    Lance Prothro

    2005-01-01

    Recently acquired mineralogic data from drill hole samples in Yucca Flat show that the tuff confining unit (TCU) can be subdivided into three mineralogic zones based on the relative abundances of primary and secondary mineral assemblages. These zones are (1) an upper zone characterized by the abundance of the zeolite mineral clinoptilolite with lesser amounts of felsic and clay minerals; (2) a middle zone with felsic minerals dominant over clinoptilolite and clay minerals; and (3) a basal argillic zone where clay minerals are dominant over felsic minerals and clinoptilolite. Interpretation of the mineralogic data, along with lithologic, stratigraphic, and geophysical data from approximately 500 drill holes, reveals a three-layer mineralogic model for the TCU that shows all three zones are extensive beneath Yucca Flat. The mineralogic model will be used to subdivide the TCU in the Yucca Flat hydrostratigraphic framework model, resulting in a more accurate and versatile framework model. In addition, the identification of the type, quantity, and distribution of minerals within each TCU layer will permit modelers to better predict the spatial distribution and extent of contaminant transport from underground tests in Yucca Flat, at both the level of the hydrologic source term and the corrective action unit

  4. Incremental heating of Bishop Tuff sanidine reveals preeruptive radiogenic Ar and rapid remobilization from cold storage

    Science.gov (United States)

    Andersen, Nathan L.; Jicha, Brian R.; Singer, Brad S.; Hildreth, Wes

    2017-11-01

    Accurate and precise ages of large silicic eruptions are critical to calibrating the geologic timescale and gauging the tempo of changes in climate, biologic evolution, and magmatic processes throughout Earth history. The conventional approach to dating these eruptive products using the 40Ar/39Ar method is to fuse dozens of individual feldspar crystals. However, dispersion of fusion dates is common and interpretation is complicated by increasingly precise data obtained via multicollector mass spectrometry. Incremental heating of 49 individual Bishop Tuff (BT) sanidine crystals produces 40Ar/39Ar dates with reduced dispersion, yet we find a 16-ky range of plateau dates that is not attributable to excess Ar. We interpret this dispersion to reflect cooling of the magma reservoir margins below ˜475 °C, accumulation of radiogenic Ar, and rapid preeruption remobilization. Accordingly, these data elucidate the recycling of subsolidus material into voluminous rhyolite magma reservoirs and the effect of preeruptive magmatic processes on the 40Ar/39Ar system. The youngest sanidine dates, likely the most representative of the BT eruption age, yield a weighted mean of 764.8 ± 0.3/0.6 ka (2σ analytical/full uncertainty) indicating eruption only ˜7 ky following the Matuyama‑Brunhes magnetic polarity reversal. Single-crystal incremental heating provides leverage with which to interpret complex populations of 40Ar/39Ar sanidine and U-Pb zircon dates and a substantially improved capability to resolve the timing and causal relationship of events in the geologic record.

  5. Three-dimensional modeling of flow through fractured tuff at Fran Ridge

    International Nuclear Information System (INIS)

    Eaton, R.R.; Ho, C.K.; Glass, R.J.; Nicholl, M.J.; Arnold, B.W.

    1996-01-01

    Numerical studies have been made of an infiltration experiment at Fran Ridge using the TOUGH2 code to aid in the selection of computational models for performance assessment. The exercise investigates the capabilities of TOUGH2 to model transient flows through highly fractured tuff and provides a possible means of calibration. Two distinctly different conceptual models were used in the TOUGH2 code, the dual permeability model and the equivalent continuum model. The infiltration test modeled involved the infiltration of dyed ponded water for 36 minutes. The 205 gallon filtration of water observed in the experiment was subsequently modeled using measured Fran Ridge fracture frequencies, and a specified fracture aperture of 285 μm. The dual permeability formulation predicted considerable infiltration along the fracture network, which was in agreement with the experimental observations. As expected, minimal fracture penetration of the infiltrating water was calculated using the equivalent continuum model, thus demonstrating that this model is not appropriate for modeling the highly transient experiment. It is therefore recommended that the dual permeability model be given priority when computing high-flux infiltration for use in performance assessment studies

  6. Concentration of carbonate admixture from opalized tuff into one separate fraction

    International Nuclear Information System (INIS)

    Bogoevski, Slobodan; Boshkovski, Boshko

    2016-01-01

    White opalized tuff (from the Strmosh locality, Probishtip), as a raw silicate amorphous material, contains some quantity of admixtures. The total quantity of admixtures amounts is about 8% mass. Mine powdery ingredients are homogeneously distributed into the basic silicate mass.Carbonate material is a significant part of present admixtures, and it is possible to be separated with controlled milling. Milling parameters (type and time of milling) enables to concentrate the present CaCO 3 in granulometric fraction<0.032 μm, after 30 min. milling. Reliable evidence about afore mentioned separation is shown with simultaneous view of the results of silicate chemical analysis, DT/TG analysis (750 - 850 °C), and sieve-analysis.From the X-ray analysis it is evident that the present carbonate material exists in crypto crystal to amorphous state. The space where CaCO 3 is hidden, presents the place between basic silicate particles inside the groups, generally with dimensions about 40 to 60 μm. The concentration of CaCO 3 appears when this particle group goes to the process of disintegration. (author)

  7. Uncertainties in sealing a nuclear waste repository in partially saturated tuff

    International Nuclear Information System (INIS)

    Tillerson, J.R.; Fernandez, J.A.; Hinkebein, T.E.

    1989-01-01

    Sealing a nuclear waste repository in partially saturated tuff presents unique challenges to assuring performance of sealing components. Design and performance of components for sealing shafts, ramps, drifts, and exploratory boreholes depend on specific features of both the repository design and the site; of particular importance is the hydrologic environment in the unsaturated zone, including the role of fracture flow. Repository design features important to sealing of a repository include the size and location of shaft and ramp accesses, excavation methods, and the underground layout features such as grade (drainage direction) and location relative to geologic structure. Uncertainties about seal components relate to the postclosure environment for the seals, the emplacement methods, the material properties, and the potential performance of the components. An approach has been developed to reduce uncertainties and to increase confidence in seal performance; it includes gathering extensive site characterization data, establishing conservative design requirements, testing seal components in laboratory and field environments, and refining designs of both the seals and the repository before seals are installed. 9 refs., 5 figs., 2 tabs

  8. Preliminary safety assessment study for the conceptual design of a repository in tuff at Yucca Mountain

    International Nuclear Information System (INIS)

    Jackson, J.L.; Gram, H.F.; Hong, K.J.; Ng, H.S.; Pendergrass, A.M.

    1984-12-01

    Preliminary estimates of the upper bounds on postulated worst-case radiological releases resulting from possible accidents during the operating period of a prospective repository in tuff at Yucca Mountain are presented. Possible disrupting events are screened to identify the accidents of greatest potential consequence. The radiological dose commitments for the general public and repository personnel are estimated for postulated releases caused by natural phenomena, man-made events, and operational accidents. All postulated worst-case releases result in doses to the public that are lower than the 0.5-rem, whole-body dose-per-accident limit set by the Nuclear Regulatory Commission (NRC) in 10 CFR 60. Doses to repository personnel are within the NRC's 5.0-rem/yr occupational exposure limit set in 10 CFR 20 for normal operations. Doses are within this limit for all accidents except the transportation accident and fire in a drift. A preliminary risk assessment has also been performed. Based on this preliminary safety study, the proposed site boundaries and design criteria routinely used in constructing nuclear facilities appear to be adequate to protect the safety of the general public during the operating phase of the repository

  9. Three-dimensional modeling of flow through fractured tuff at Fran Ridge

    International Nuclear Information System (INIS)

    Eaton, R.R.; Ho, C.K.; Glass, RJ.; Nicholl, M.J.; Arnold, B.W.

    1996-09-01

    Numerical studies have been made of an infiltration experiment at Fran Ridge using the TOUGH2 code to aid in the selection of computational models for performance assessment. The exercise investigates the capabilities of TOUGH2 to model transient flows through highly fractured tuff and provides a possible means of calibration. Two distinctly different conceptual models were used in the TOUGH2 code, the dual permeability model and the equivalent continuum model. The infiltration test modeled involved the infiltration of dyed ponded water for 36 minutes. The 205 gallon infiltration of water observed in the experiment was subsequently modeled using measured Fran Ridge fracture frequencies, and a specified fracture aperture of 285 microm. The dual permeability formulation predicted considerable infiltration along the fracture network, which was in agreement with the experimental observations. As expected, al fracture penetration of the infiltrating water was calculated using the equivalent continuum model, thus demonstrating that this model is not appropriate for modeling the highly transient experiment. It is therefore recommended that the dual permeability model be given priority when computing high-flux infiltration for use in performance assessment studies

  10. Nuclear criticality safety analysis of a spent fuel waste package in a tuff repository

    International Nuclear Information System (INIS)

    Weren, B.H.; Capo, M.A.; O'Neal, W.C.

    1983-12-01

    An assessment has been performed of the criticality potential associated with the disposal of spent fuel in a tuff geology above the water table. Eleven potential configurations were defined which cover a vast range of geometries and conditions from the nominal configuration at emplacement to a hypothetical configuration thousands of years after emplacement in which the structure is gone, the fuel pellets disintegrated and the borehole flooded. Of these eleven configurations, four have been evaluated at this time. The results of this evaluation indicate that even with very conservative assumptions (4.5 w/o fresh fuel), criticality is not a problem for the nominal configuration either dry or fully flooded. In the cases where the condition of the waste package is assumed to have severely deteriorated, over long times, calculations were performed with less conservative assumptions (depleted fuel). An assessment of these calculations indicates that criticality safety could be demonstrated if the depletion of the fissile inventory during fuel irradiation is taken into account. A detailed discussion of the calculations performed is presented in this report. Also included are a description of the configurations which were considered, the analytical methods and models used, and a discussion of additional related work which should be performed. 15 references, 11 figures, 8 tables

  11. Experimental Analysis and Process Modeling of Carbon Dioxide Removal Using Tuff

    Directory of Open Access Journals (Sweden)

    Emanuele Bonamente

    2016-12-01

    Full Text Available Removal of carbon dioxide via selective adsorption is a key process to obtain consumer-grade natural gas from biogas and, more generally, CO2 capture and sequestration from gaseous mixtures. The aim of this work is the characterization and classification of a natural alternative to synthetic zeolites that could be used as a carbon dioxide adsorbent. Tuff particulate, easily available as a byproduct of the construction industry, was tested with different laboratory procedures to verify its suitability for CO2 removal applications. Relevant physical and adsorption properties were measured during an intensive experimental campaign. Porosity, pore size distribution, and specific surface area were obtained with mercury intrusion porosimetry. Adsorption isotherms and saturation curves were obtained using two custom experimental apparatuses. The selective adsorption was finally modeled using an original phenomenological parameterization, and a simplified simulation of the process was performed using a computational fluid dynamic approach, validated against observed data. Results show that natural zeolites represent a very promising and sustainable alternative to synthetic zeolites in pressure swing adsorption processes for CO2 removal.

  12. Survey of geophysical techniques for site characterization in basalt, salt and tuff

    International Nuclear Information System (INIS)

    Jones, G.M.; Blackey, M.E.; Rice, J.E.; Murphy, V.J.; Levine, E.N.; Fisk, P.S.; Bromery, R.W.

    1987-07-01

    Geophysical techniques may help determine the nature and extent of faulting in the target areas, along with structural information that would be relevant to questions concerning the future integrity of a high-level-waste repository. Chapters focus on particular geophysical applications to four rock types - basalt, bedded salt, domal salt and tuff - characteristic of the sites originally proposed for site characterization. No one geophysical method can adequately characterize the geological structure beneath any site. The seismic reflection method, which is generally considered to be the most incisive of the geophysical techniques, has to date provided only marginal information on structure at the depth of the proposed repository at the Hanford, Washington, site, and no useful results at all at the Yucca Mountain, Nevada, site. This result is partially due to geological complexity beneath these sites, but may also be partially attributed to the use of inappropriate acquisition and processing parameters. To adequately characterize a site using geophysics, modifications will have to be made to standard techniques to emphasize structural details at the depths of interest. 137 refs., 43 figs., 4 tabs

  13. Properties of Vulcanized Polyisoprene Rubber Composites Filled with Opalized White Tuff and Precipitated Silica

    Directory of Open Access Journals (Sweden)

    Suzana Samaržija-Jovanović

    2014-01-01

    Full Text Available Opalized white tuff (OWT with 40 μm average particle size and 39.3 m2/g specific surface area has been introduced into polyisoprene rubber (NR. Their reinforcing effects were evaluated by comparisons with those from precipitated silica (PSi. The cure characteristic, apparent activation energy of cross-link (Eac and reversion (Ear, and mechanical properties of a variety of composites based on these rubbers were studied. This was done using vulcanization techniques, mechanical testing, and scanning electron microscopy (SEM. The results showed that OWT can greatly improve the vulcanizing process by shortening the time of optimum cure (tc90 and the scorch time (ts2 of cross-linked rubber composites, which improves production efficiency and operational security. The rubber composites filled with 50 phr of OWT were found to have good mechanical and elastomeric properties. The tensile strengths of the NR/OWT composites are close to those of NR/PSi composites, but the tear strength and modulus are not as good as the corresponding properties of those containing precipitated silica. Morphology results revealed that the OWT is poorly dispersed in the rubber matrix. According to that, the lower interactions between OWT and polyisoprene rubber macromolecules are obtained, but similar mechanical properties of NR/OWT (100/50 rubber composites compared with NR/PSi (100/50 rubber composites are resulted.

  14. Rectangular Schlumberger resistivity arrays for delineating vadose zone clay-lined fractures in shallow tuff

    International Nuclear Information System (INIS)

    Miele, M.; Laymon, D.; Gilkeson, R.; Michelotti, R.

    1996-01-01

    Rectangular Schlumberger arrays can be used for 2-dimensional lateral profiling of apparent resistivity at a unique current electrode separation, hence single depth of penetration. Numerous apparent resistivity measurements are collected moving the potential electrodes (fixed MN spacing) within a rectangle of defined dimensions. The method provides a fast, cost-effective means for the collection of dense resistivity data to provide high-resolution information on subsurface hydrogeologic conditions. Several rectangular Schlumberger resistivity arrays were employed at Los Alamos National Laboratory (LANL) from 1989 through 1995 in an area adjacent to and downhill from an outfall pipe, septic tank, septic drainfield, and sump. Six rectangular arrays with 2 AB spacings were used to delineate lateral low resistivity anomalies that may be related to fractures that contain clay and/or vadose zone water. Duplicate arrays collected over a three year time period exhibited very good data repeatability. The properties of tritium make it an excellent groundwater tracer. Because tritium was present in discharged water from all of the anthropogenic sources in the vicinity it was used for this purpose. One major low resistivity anomaly correlates with relatively high tritium concentrations in the tuff. This was determined from borehole samples collected within and outside of the anomalous zone. The anomaly is interpreted to be due to fractures that contain clay from the soil profile. The clay was deposited in the fractures by aeolian processes and by surface water infiltration. The fractures likely served as a shallow vadose zone groundwater pathway

  15. Proposed sealing field tests for a potential high-level radioactive waste repository in unsaturated tuff

    International Nuclear Information System (INIS)

    Fernandez, J.A.; Case, J.B.; Tyburski, J.

    1992-01-01

    This paper contains a general description of the field tests proposed for the Yucca Mountain Site Characterization Project repository sealing program. The tests are intended to resolve various performance and emplacement concerns associated with sealing components. Ten discrete tests are proposed to address these concerns. These tests are divided into two categories -- simple and complex tests. The simple tests are: the small-scale in situ tests: the intermediate-scale borehole seal tests; the fracture grouting tests; the surface backfill tests; and the grouted rock mass tests. The complex tests are the seepage control tests; in situ backfill tests; in situ bulkhead tests; large-scale shaft seal tests; and remote borehole seal tests. These tests are proposed to be performed in welded and nonwelded tuff environments. The final selection of sealing tests will depend on the nature of the geologic and hydrologic conditions encountered during the development of the exploratory studies facility. Some tests may be performed before license application and some after license application

  16. Permeameter studies of water flow through cement and clay borehole seals in granite, basalt and tuff

    International Nuclear Information System (INIS)

    South, D.L.; Daemen, J.J.K.

    1986-10-01

    Boreholes near a repository must be sealed to prevent rapid migration of radionuclide-contaminated water to the accessible environment. The objective of this research is to assess the performance of borehole seals under laboratory conditions, particularly with regard to varying stress fields. Flow through a sealed borehole is compared with flow through intact rock. Cement or bentonite seals have been tested in granite, basalt, and welded tuff. The main conclusion is that under laboratory conditions, existing commercial materials can form high quality seals. Triaxial stress changes about a borehole do not significantly affect seal performance if the rock is stiffer than the seal. Temperature but especially moisture variations (drying) significantly degrade the quality of cement seals. Performance partially recovers upon resaturation. A skillfully sealed borehole may be as impermeable as the host rock. Analysis of the influence of relative seal-rock permeabilities shows that a plug with permeability one order of magnitude greater than that of the rock results in a flow increase through the hole and surrounding rock of only 1-1/2 times compared to the undisturbed rock. Since a borehole is only a small part of the total rock mass, the total effect is even less pronounced. The simplest and most effective way to decrease flow through a rock-seal system is to increase the seal length, assuming it can be guaranteed that no dominant by-pass flowpath through the rock exists

  17. Closure development for high-level nuclear waste containers for the tuff repository

    International Nuclear Information System (INIS)

    Robitz, E.S. Jr.; McAninch, M.D. Jr.; Edmonds, D.P.; Babcock and Wilcox Co., Alliance, OH

    1990-09-01

    This report summarizes Phase 1 activities for closure development of the high-level nuclear waste package task for the tuff repository. Work was conducted under U.S. Department of Energy (DOE) Contract 9172105, administered through the Lawrence Livermore National Laboratory (LLNL), as part of the Yucca Mountain Project (YMP), funded through the DOE Office of Civilian Radioactive Waste Management (OCRWM). The goal of this phase was to select five closure processes for further evaluation in later phases of the program. A decision tree methodology was utilized to perform an objective evaluation of 15 potential closure processes. Information was gathered via a literature survey, industrial contacts, and discussions with project team members, other experts in the field, and the LLNL waste package task staff. The five processes selected were friction welding, electron beam welding, laser beam welding, gas tungsten arc welding, and plasma arc welding. These are felt to represent the best combination of weldment material properties and process performance in a remote, radioactive environment. Conceptual designs have been generated for these processes to illustrate how they would be implemented in practice. Homopolar resistance welding was included in the Phase 1 analysis, and developments in this process will be monitored via literature in Phases 2 and 3. Work was conducted in accordance with the YMP Quality Assurance Program. 223 refs., 20 figs., 9 tabs

  18. The petrologic evolution and pre-eruptive conditions of the rhyolitic Kos Plateau Tuff (Aegean arc)

    Science.gov (United States)

    Bachmann, Olivier

    2010-09-01

    The Kos Plateau Tuff is a large (>60 km3) and young (160 k.y.) calc-alkaline, high-SiO2 rhyolitic ignimbrite from the active Kos-Nisyros volcanic center in the Aegean arc (Greece). Combined textural, petrological and geochemical information suggest that (1) the system evolved dominantly by crystal fractionation from (mostly unerupted) more mafic parents, (2) the magma chamber grew over ≥ 250 000 years at shallow depth (˜1.5-2.5 kb) and was stored as a H2O-rich crystalline mush close to its solidus (˜670-750°C), (3) the eruption occurred after a reheating event triggered by the intrusion of hydrous mafic magma at the base of the rhyolitic mush. Rare banded pumices indicate that the mafic magma only mingled with a trivial portion of resident crystal-rich rhyolite; most of the mush was remobilized following partial melting of quartz and feldspars induced by advection of heat and volatiles from the underplated, hotter mafic influx.

  19. The melt inclusion record from the rhyolitic Kos Plateau Tuff (Aegean Arc)

    Science.gov (United States)

    Bachmann, Olivier; Wallace, Paul J.; Bourquin, Julie

    2010-02-01

    The >60 km3 rhyolitic Kos Plateau Tuff provides an exceptional probe into the behavior of volatile components in highly evolved arc magmas: it is crystal-rich (30-40 vol% crystals), was rapidly quenched by the explosive eruptive process, and contains abundant homogeneous melt inclusions in large quartz crystals. Several methods for measuring major, trace and volatile element concentrations (SIMS, FTIR, Raman spectroscopy, electron microprobe, LA-ICPMS) were applied to these melt inclusions. We found a ~2 wt% range of H2O contents (4.5-6.5 wt% H2O, measured independently by SIMS, FTIR, and Raman spectroscopy) and relatively low CO2 concentrations (15-140 ppm measured by FTIR, with most analyses <100 ppm). No obvious correlations between H2O, CO2, major and trace elements are observed. These observations require a complex, protracted magma evolution in the upper crust that included: (1) vapor-saturated crystallization in a chamber located between 1.5 and 2.5 kb pressure, (2) closed-system degassing (with up to 10 vol% exsolved gas) as melts percolated upwards through a vertically extensive mush zone (2-4 km thick), and (3) periodic gas fluxing from subjacent, more mafic and more CO2-rich magma, which is preserved as andesite bands in pumices. These processes can account for the range of observed H2O and CO2 values and the lack of correlation between volatiles and trace elements in the melt inclusions.

  20. Precursory activity of the 161 ka Kos Plateau Tuff eruption, Aegean Sea (Greece)

    Science.gov (United States)

    Piper, David J. W.; Pe-Piper, Georgia; Lefort, Darren

    2010-08-01

    The Kos Plateau Tuff (KPT) eruption of 161 ka was the largest explosive Quaternary eruption in the eastern Mediterranean. We have discovered an uplifted beach deposit of abraded pumice cobbles, directly overlain by the KPT. The pumice cobbles resemble pumice from the KPT in petrography and composition and differ from Plio-Pleistocene rhyolites on the nearby Kefalos Peninsula. The pumice contains enclaves of basaltic andesite showing chilled lobate margins, suggesting co-existence of two magmas. The deposit provides evidence that the precursory phase of the KPT eruption produced pumice rafts, and defines the paleoshoreline for the KPT, which elsewhere was deposited on land. The beach deposit has been uplifted about 120 m since the KPT eruption, whereas the present marine area south of Kos has subsided several hundred metres, as a result of regional neotectonics. The basaltic andesite is more primitive than other mafic rocks known from the Kos-Nisyros volcanic centre and contains phenocrysts of Fo89 olivine, bytownite, enstatite and diopside. Groundmass amphibole suggests availability of water in the final stages of magma evolution. Geochemical and mineralogical variation in the mafic products of the KPT eruption indicate that fractionation of basaltic magma in a base-of-crust magma chamber was followed by mixing with rhyolitic magma during eruption. Low eruption rates during the precursory activity may have minimised the extent of mixing and preserved the end-member magma types.

  1. Rapid estimate of solid volume in large tuff cores using a gas pycnometer

    International Nuclear Information System (INIS)

    Thies, C.; Geddis, A.M.; Guzman, A.G.

    1996-09-01

    A thermally insulated, rigid-volume gas pycnometer system has been developed. The pycnometer chambers have been machined from solid PVC cylinders. Two chambers confine dry high-purity helium at different pressures. A thick-walled design ensures minimal heat exchange with the surrounding environment and a constant volume system, while expansion takes place between the chambers. The internal energy of the gas is assumed constant over the expansion. The ideal gas law is used to estimate the volume of solid material sealed in one of the chambers. Temperature is monitored continuously and incorporated into the calculation of solid volume. Temperature variation between measurements is less than 0.1 degrees C. The data are used to compute grain density for oven-dried Apache Leap tuff core samples. The measured volume of solid and the sample bulk volume are used to estimate porosity and bulk density. Intrinsic permeability was estimated from the porosity and measured pore surface area and is compared to in-situ measurements by the air permeability method. The gas pycnometer accommodates large core samples (0.25 m length x 0.11 m diameter) and can measure solid volume greater than 2.20 cm 3 with less than 1% error

  2. Rapid estimate of solid volume in large tuff cores using a gas pycnometer

    Energy Technology Data Exchange (ETDEWEB)

    Thies, C. [ed.; Geddis, A.M.; Guzman, A.G. [and others

    1996-09-01

    A thermally insulated, rigid-volume gas pycnometer system has been developed. The pycnometer chambers have been machined from solid PVC cylinders. Two chambers confine dry high-purity helium at different pressures. A thick-walled design ensures minimal heat exchange with the surrounding environment and a constant volume system, while expansion takes place between the chambers. The internal energy of the gas is assumed constant over the expansion. The ideal gas law is used to estimate the volume of solid material sealed in one of the chambers. Temperature is monitored continuously and incorporated into the calculation of solid volume. Temperature variation between measurements is less than 0.1{degrees}C. The data are used to compute grain density for oven-dried Apache Leap tuff core samples. The measured volume of solid and the sample bulk volume are used to estimate porosity and bulk density. Intrinsic permeability was estimated from the porosity and measured pore surface area and is compared to in-situ measurements by the air permeability method. The gas pycnometer accommodates large core samples (0.25 m length x 0.11 m diameter) and can measure solid volume greater than 2.20 cm{sup 3} with less than 1% error.

  3. Permeameter studies of water flow through cement and clay borehole seals in granite, basalt and tuff

    Energy Technology Data Exchange (ETDEWEB)

    South, D.L.; Daemen, J.J.K.

    1986-10-01

    Boreholes near a repository must be sealed to prevent rapid migration of radionuclide-contaminated water to the accessible environment. The objective of this research is to assess the performance of borehole seals under laboratory conditions, particularly with regard to varying stress fields. Flow through a sealed borehole is compared with flow through intact rock. Cement or bentonite seals have been tested in granite, basalt, and welded tuff. The main conclusion is that under laboratory conditions, existing commercial materials can form high quality seals. Triaxial stress changes about a borehole do not significantly affect seal performance if the rock is stiffer than the seal. Temperature but especially moisture variations (drying) significantly degrade the quality of cement seals. Performance partially recovers upon resaturation. A skillfully sealed borehole may be as impermeable as the host rock. Analysis of the influence of relative seal-rock permeabilities shows that a plug with permeability one order of magnitude greater than that of the rock results in a flow increase through the hole and surrounding rock of only 1-1/2 times compared to the undisturbed rock. Since a borehole is only a small part of the total rock mass, the total effect is even less pronounced. The simplest and most effective way to decrease flow through a rock-seal system is to increase the seal length, assuming it can be guaranteed that no dominant by-pass flowpath through the rock exists.

  4. Fragmentation, nucleation and migration of crystals and bubbles in the Bishop Tuff rhyolitic magma

    Energy Technology Data Exchange (ETDEWEB)

    Gualda, G.; Cook, D.L.; Chopra, R.; Qin, L.; Anderson, A.T.; Rivers, M. (UC)

    2010-12-07

    The Bishop Tuff (USA) is a large-volume, high-silica pyroclastic rhyolite. Five pumice clasts from three early stratigraphic units were studied. Size distributions were obtained using three approaches: (1) crushing, sieving and winnowing (reliable for crystals >100 {micro}m); (2) microscopy of 1 mm{sup 3} fragments (preferable for crystals <100 {micro}m); and (3) computerised X-ray microtomography of {approx}1 cm{sup 3} pumice pieces. Phenocryst fragments coated with glass are common, and the size distributions for all crystals are concave-upward, indicating that crystal fragmentation is an important magmatic process. Three groups are recognised, characterised by: (1) high-density (0.759-0.902 g cm{sup -3}), high-crystal content (14.4-15.3 wt.%) and abundant large crystals (>800 {micro}m); concave-downward size distributions for whole crystals indicate late-stage growth with limited nucleation, compatible with the slow cooling of a large, gas-saturated, stably stratified magma body; (2) low-density (0.499 g cm{sup -3}), low-crystal content (6.63 wt.%) and few large crystals; the approximately linear size distribution reveals that nucleation was locally important, perhaps close to the walls; and (3) intermediate characteristics in all respects. The volumetric fraction of bubbles inversely correlates with the number of large crystals. This is incompatible with isobaric closed-system crystallisation, but can be explained by sinking of large crystals and rise of bubbles in the magma.

  5. Recent developments in stochastic modeling and upscaling of hydrologic properties in tuff

    International Nuclear Information System (INIS)

    Rautman, C.A.; Robey, T.H.

    1992-01-01

    A set of detailed geostatistical simulations of porosity has been produced for a layered stratigraphic sequence of welded and nonwelded volcanic tuffs at Yucca Mountain, Nevada. The simulations are produced using a composite. model of spatial continuity and they are highly conditioned to abundant drill hole (core) information. A set of derivative simulations of saturated hydraulic conductivity has been produced, in the absence of conditioning data, using a cross-variable relationship developed from similar data elsewhere. The detailed simulations reproduce both the major stratigraphic units and finer scale layering indicated by the drill hole data. These simulations have been scaled up several order of magnitude to represent block-scale effective hydrologic properties suitable for use in numerical modeling of groundwater flow and transport. The upscaling process involves the reformulation of a previously reported method that iteratively adapts an initial arbitrary grid to ''homogenize'' the detailed hydraulic properties contained within the adjusted cell limits and to minimize the size of cell in highly heterogeneous regions. Although the computation of the block-effective property involves simple numerical averaging, the blocks over which these averages are computed are relatively homogeneous, which reduces the numerical difficulties involved in averaging non-additive properties, such as permeability. The entire process of simulation and upscaling is rapid and computationally efficient compared with alterative techniques. It is thus suitable for the Monte Carlo evaluation of the uncertainty in site characterization as it affects the results of groundwater flow and transport calculations

  6. 77 FR 59607 - Black Canyon Hydro, LLC; Notice of Environmental Site Review

    Science.gov (United States)

    2012-09-28

    ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 14110-001] Black Canyon Hydro, LLC; Notice of Environmental Site Review On Wednesday, October 3, 2012, at 3 p.m., Commission staff will be participating in an environmental site review for the proposed Black Canyon Hydroelectric Project. All interested participants should mee...

  7. 75 FR 10308 - Fire Management Plan, Final Environmental Impact Statement, Record of Decision, Grand Canyon...

    Science.gov (United States)

    2010-03-05

    ... DEPARTMENT OF THE INTERIOR National Park Service Fire Management Plan, Final Environmental Impact... Statement for the Fire Management Plan, Grand Canyon National Park. SUMMARY: Pursuant to the National... the Record of Decision for the Fire Management Plan, Grand Canyon National Park, Arizona. On January...

  8. Effects of trees on the dilution of vehicle exhaust emissions in urban street canyons

    NARCIS (Netherlands)

    Gromke, C.B.; Ruck, B.

    2009-01-01

    In order to investigate the natural ventilation and air quality of urban street canyons with trees, boundary layer wind tunnel studies at a small-scale model have been performed. Concentrations in street canyons with a tracer gas emitting line source at the ground level and one row of trees arranged

  9. A Numerical Simulation of Traffic-Related Air Pollution Exposures in Urban Street Canyons

    Science.gov (United States)

    Liu, J.; Fu, X.; Tao, S.

    2016-12-01

    Urban street canyons are usually associated with intensive vehicle emissions. However, the high buildings successively along both sides of a street block the dispersion of traffic-generated air pollutants, which enhances human exposure and adversely affects human health. In this study, an urban scale traffic pollution dispersion model is developed with the consideration of street distribution, canyon geometry, background meteorology, traffic assignment, traffic emissions and air pollutant dispersion. Vehicle exhausts generated from traffic flows will first disperse inside a street canyon along the micro-scale wind field (generated by computational fluid dynamics (CFD) model) and then leave the street canyon and further disperse over the urban area. On the basis of this model, the effects of canyon geometry on the distribution of NOx and CO from traffic emissions were studied over the center of Beijing, China. We found that an increase of building height along the streets leads to higher pollution levels inside streets and lower pollution levels outside, resulting in higher domain-averaged concentrations over the area. In addition, street canyons with equal (or highly uneven) building heights on two sides of a street tend to lower the urban-scale air pollution concentrations at pedestrian level. Our results indicate that canyon geometry strongly influences human exposure to traffic pollutants in the populated urban area. Carefully planning street layout and canyon geometry in consideration of traffic demand as well as local weather pattern may significantly reduce the chances of unhealthy air being inhaled by urban residents.

  10. Strategic guidelines for street canyon geometry to achieve sustainable street air quality

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Andy T.; So, Ellen S.P.; Samad, Subash C. [Hong Kong Univ., Dept. of Mechanical Engineering, Hong Kong (China)

    2001-08-01

    This paper is concerned with the motion of air within the urban street canyon and is directed towards a deeper understanding of pollutant dispersion with respect to various simple canyon geometries and source positions. Taking into account the present days typical urban configurations, three principal flow regimes 'isolated roughness flow', 'skimming flow' and 'wake interference flow' (Boundary Layer Climates, 2nd edition, Methuen, London) and their corresponding pollutant dispersion characteristics are studied for various canopies aspect ratios, namely relative height (h{sub 2}/H{sub 1}), canyon height to width ratio (h/w) and canyon length to height ratio (l/h). A field-size canyon has been analysed through numerical simulations using the standard k-{sup {epsilon}} turbulence closure model. It is found that the pollutant transport and diffusion is strongly dependent upon the type of flow regime inside the canyon and exchange between canyon and the above roof air. Some rules of thumbs have been established to get urban canyon geometries for efficient dispersion of pollutants. (Author)

  11. Captured in Stone: Women in the Rock Art of Canyon de Chelly.

    Science.gov (United States)

    Travis, Tara

    1997-01-01

    Describes the pictographs (painted images on stone) and petroglyphs (pecked images on stone) found in the Canyon de Chelly National Monument in Arizona. Canyon de Chelly includes one of the largest concentrations of American Indian rock art in the southwest. Discusses the depiction of women in these images. (MJP)

  12. 75 FR 27550 - Electrical Interconnection of the Juniper Canyon I Wind Project

    Science.gov (United States)

    2010-05-17

    ... DEPARTMENT OF ENERGY Bonneville Power Administration Electrical Interconnection of the Juniper Canyon I Wind Project AGENCY: Bonneville Power Administration (BPA), Department of Energy (DOE). ACTION... would be generated from their proposed Juniper Canyon I Wind Energy Project (Wind Project) in Klickitat...

  13. 33 CFR 165.1155 - Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California.

    Science.gov (United States)

    2010-07-01

    ... Nuclear Power Plant, Avila Beach, California. 165.1155 Section 165.1155 Navigation and Navigable Waters... Coast Guard District § 165.1155 Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach... surface to bottom, within a 2,000 yard radius of Diablo Canyon Nuclear Power Plant centered at position 35...

  14. Draft environmental assessment: Lavender Canyon site, Utah. Nuclear Waste Policy Act (Section 112)

    International Nuclear Information System (INIS)

    1984-12-01

    In February 1983, the US Department of Energy (DOE) identified the Lavender Canyon site in Utah, as one of nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Lavender Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for Nuclear Waste Repositories. These evaluations are reported in this draft environmental assessment (EA), which is being issued for public review and comment. The DOE findings and determinations that are based on these evaluations are preliminary and subject to public review and comment. A final EA will be prepared after considering the comments received. On the basis of the evaluations contained in this draft EA, the DOE has found that the Lavender Canyon site is not disqualified under the guidelines. The site is contained in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site - the Davis Canyon site. Although the Lavender Canyon site appears to be suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of these findings, the DOE is proposing to nominate the Davis Canyon site rather than the Lavender Canyon site as one of the five sites suitable for characterization

  15. Post-middle Miocene Tuffs of Bodie Hills and Mono Basin, California: Paleomagnetic Reference Directions and Vertical Axis Rotation

    Science.gov (United States)

    Lindeman, J. R.; Pluhar, C. J.; Farner, M. J.

    2013-12-01

    The relative motions of the Pacific and North American plates about the Sierra Nevada-North American Euler pole is accommodated by dextral slip along the San Andreas Fault System (~75%) and the Walker Lane-Eastern California Shear Zone system of faults, east of the Sierra Nevada microplate (~25%). The Bodie Hills and Mono Basin regions lie within the Walker Lane and partially accommodate deformation by vertical axis rotation of up to 60o rotation since ~9.4 Ma. This region experienced recurrent eruptive events from mid to late Miocene, including John et al.'s (2012) ~12.05 Ma Tuff of Jack Springs (TJS) and Gilbert's (1968) 11.1 - 11.9 Ma 'latite ignimbrite' east of Mono Lake. Both tuffs can be identified by phenocrysts of sanidine and biotite in hand specimens, with TJS composed of a light-grey matrix and the latite ignimbrite composed of a grey-black matrix. Our paleomagnetic results show these units to both be normal polarity, with the latite ignimbrite exhibiting a shallow inclination. TJS's normal polarity is consistent with emplacement during subchron C5 An. 1n (12.014 - 12.116 Ma). The X-ray fluorescence analyses of fiamme from TJS in Bodie Hills and the latite ignimbrite located east of Mono Lake reveal them both to be rhyolites with the latite ignimbrite sharing elevated K composition seen in the slightly younger Stanislaus Group (9.0 - 10.2 Ma). We establish a paleomagnetic reference direction of D = 352.8o I = 42.7o α95 = 7.7o n = 5 sites (42 samples) for TJS in the Bodie Hills in a region hypothesized by Carlson (2012) to have experienced low rotation. Our reference for Gilbert's latite ignimbrite (at Cowtrack Mountain) is D = 352.9o I = 32.1o α95 = 4.7o. This reference locality is found on basement highland likely to have experienced less deformation then the nearby Mono Basin since ignimbrite emplacement. Paleomagnetic results from this latite ignimbrite suggests ~98.2o × 5.5o of clockwise vertical axis rotation of parts of eastern Mono Basin since

  16. 75 FR 26788 - Public Land Order No. 7742; Withdrawal of Public Land for the Manning Canyon Tailings Repository; UT

    Science.gov (United States)

    2010-05-12

    ... 79765] Public Land Order No. 7742; Withdrawal of Public Land for the Manning Canyon Tailings Repository... period of 5 years to protect the integrity of the Manning Canyon Tailings Repository and surrounding... withdrawal is to protect public health and safety and the Federal investment in the Manning Canyon Tailings...

  17. 76 FR 14745 - Notice To Rescind a Notice of Intent To Prepare an Environmental Impact Statement, Ada and Canyon...

    Science.gov (United States)

    2011-03-17

    ... To Prepare an Environmental Impact Statement, Ada and Canyon Counties, ID AGENCY: Federal Highway... prepare an Environmental Impact Statement for a proposed highway project in Ada and Canyon County, Idaho... Highway 44 from Exit 25 at Interstate 84 in Canyon County to Ballantyne Lane in Ada County. The project is...

  18. Aerodynamic effects of trees on pollutant concentration in street canyons.

    Science.gov (United States)

    Buccolieri, Riccardo; Gromke, Christof; Di Sabatino, Silvana; Ruck, Bodo

    2009-09-15

    This paper deals with aerodynamic effects of avenue-like tree planting on flow and traffic-originated pollutant dispersion in urban street canyons by means of wind tunnel experiments and numerical simulations. Several parameters affecting pedestrian level concentration are investigated, namely plant morphology, positioning and arrangement. We extend our previous work in this novel aspect of research to new configurations which comprise tree planting of different crown porosity and stand density, planted in two rows within a canyon of street width to building height ratio W/H=2 with perpendicular approaching wind. Sulfur hexafluoride was used as tracer gas to model the traffic emissions. Complementary to wind tunnel experiments, 3D numerical simulations were performed with the Computational Fluid Dynamics (CFD) code FLUENT using a Reynolds Stress turbulence closure for flow and the advection-diffusion method for concentration calculations. In the presence of trees, both measurements and simulations showed considerable larger pollutant concentrations near the leeward wall and slightly lower concentrations near the windward wall in comparison with the tree-less case. Tree stand density and crown porosity were found to be of minor importance in affecting pollutant concentration. On the other hand, the analysis indicated that W/H is a more crucial parameter. The larger the value of W/H the smaller is the effect of trees on pedestrian level concentration regardless of tree morphology and arrangement. A preliminary analysis of approaching flow velocities showed that at low wind speed the effect of trees on concentrations is worst than at higher speed. The investigations carried out in this work allowed us to set up an appropriate CFD modelling methodology for the study of the aerodynamic effects of tree planting in street canyons. The results obtained can be used by city planners for the design of tree planting in the urban environment with regard to air quality issues.

  19. Geo-hazard by sediment mass movements in submarine canyons

    Science.gov (United States)

    Ghaith, Afif; Fakhri, Milad; Ivaldi, Roberta; Ciavola, Paolo

    2017-04-01

    Submarine mass movements and their consequences are of major concern for coastal communities and infrastructures but also for the exploitation and the development of seafloor resources. Elevated awareness of the need for better understanding of the underwater mass movement is coupled with great advances in underwater mapping technologies over the past two decades. The seafloor in the Nahr Ibrahim and Saida regions (Lebanon) is characterized by deep canyons, reaching one thousand meters depths in proximity of the coast. Signs of submarine mass movement instability related to these canyons create a connection between shallow and deep water. The presence of these canyons in a tectonically active area generates a particular drained mechanism to the sediment in form of mass movement and slumping. Identification of potential areas where slope movements could be triggered requires data with high spatial resolution. Since this area is poorly explored, in the framework of an international project between Lebanese Navy, Lebanese National Center for Marine Sciences, University of Ferrara and Italian Hydrographic Institute, we analyse the morpho-bathymetric and sedimentological characters of the coastal and shelf sectors. Multibeam echosounder and sub-bottom profiler acoustic systems calibrated with ground truths (sediment grab and core samples) allow us to characterize the nature of seafloor and sub-seafloor with particular detail to the geotechnical properties of sediments and high resolution seismic stratigraphy of the shallow layers. The detection of particular undersea features provides detail maps which are in support to littoral morpho-dynamics, coastal transport and sediment budget. Multilayer hydro-oceanographic map, referring to the seafloor dynamics in connection with deep water environment and drainage system, in accordance to the International Hydrographic Standards and nautical supports, are produced. This high resolution multibeam bathymetry dataset, integrated

  20. Marble Canyon 10 x 20 NTMS area Arizona: data report

    International Nuclear Information System (INIS)

    Heffner, J.D.

    1980-07-01

    Results of ground water and stream/surface sediment reconnaissance (HSSR) in the National Topographic Map Series (NTMS) Marble Canyon 1 0 x 2 0 quadrangle are presented. The target sampling density for all media collected was one site per 12 square kilometers. This resulted in 884 sediment samples being collected; however, dry conditions and sparse population resulted in the collection of only 2 ground water samples. Grand Canyon National Park, Glen Canyon National Recreation Area, and much Indian tribal land in the southern half of the quadrangle were not sampled. Neutron activation analysis (NAA) results are given for uranium and 16 other elements in sediments, and for uranium and 9 other elements in ground water. Mass spectrometry results are given for helium in ground water. Field measurements for sediment samples are presented in tables and maps. Statistical summaries of data and a brief description of results are given. A generalized geologic map and a summary of the geology of the area are included. Data from ground water include: water chemistry measurements (pH, conductivity, and alkalinity); physical measurements (water temperature, and scintillometer readings); and elemental analyses (U, Al, Br, Cl, Dy, F, He, Mg, Mn, Na, and V). Data from sediment sites include: water chemistry measurements (where available) for pH, conductivity, and alkalinity; and elemental analyses(U, Th, Hf, Al, Ce, Dy, Eu, Fe, La, Lu, Mn, Sc, Sm, Na, Ti, V, and Yb). Sample site descriptors (stream characteristics, vegetation, etc.) are also tabulated. Histograms, cumulative frequency, and areal distribution plots for most elements; Log U/Th, Log U/Hf, and Log U/(Th + Hf) ratios; and scintillometer readings are included

  1. Populating a Control Point Database: A cooperative effort between the USGS, Grand Canyon Monitoring and Research Center and the Grand Canyon Youth Organization

    Science.gov (United States)

    Brown, K. M.; Fritzinger, C.; Wharton, E.

    2004-12-01

    The Grand Canyon Monitoring and Research Center measures the effects of Glen Canyon Dam operations on the resources along the Colorado River from Glen Canyon Dam to Lake Mead in support of the Grand Canyon Adaptive Management Program. Control points are integral for geo-referencing the myriad of data collected in the Grand Canyon including aerial photography, topographic and bathymetric data used for classification and change-detection analysis of physical, biologic and cultural resources. The survey department has compiled a list of 870 control points installed by various organizations needing to establish a consistent reference for data collected at field sites along the 240 mile stretch of Colorado River in the Grand Canyon. This list is the foundation for the Control Point Database established primarily for researchers, to locate control points and independently geo-reference collected field data. The database has the potential to be a valuable mapping tool for assisting researchers to easily locate a control point and reduce the occurrance of unknowingly installing new control points within close proximity of an existing control point. The database is missing photographs and accurate site description information. Current site descriptions do not accurately define the location of the point but refer to the project that used the point, or some other interesting fact associated with the point. The Grand Canyon Monitoring and Research Center (GCMRC) resolved this problem by turning the data collection effort into an educational exercise for the participants of the Grand Canyon Youth organization. Grand Canyon Youth is a non-profit organization providing experiential education for middle and high school aged youth. GCMRC and the Grand Canyon Youth formed a partnership where GCMRC provided the logistical support, equipment, and training to conduct the field work, and the Grand Canyon Youth provided the time and personnel to complete the field work. Two data

  2. Ancho Canyon RF Collect, March 2, 2017: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Junor, William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Layne, John Preston [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gamble, Thomas Kirk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Quintana, Bobby Arthur [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Snelson-Gerlicher, Catherine Mary [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Goorley, John Timothy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-21

    We report the results from the March 2, 2017, Ancho Canyon RF collection. While bright electromagnetic signals were seen nearby the firing point, there were no detections of signals from the explosively-fired fuse at a collection point about 570m distant on the East Mesa. However, "liveness" tests of the East Mesa data acquisition system and checks of the timing both suggest that the collection system was working correctly. We examine possible reasons for the lack of detection. Principal among these is that the impulsive signal may be small compared to the radio frequency background on the East Mesa.

  3. Late Holocene sea ice conditions in Herald Canyon, Chukchi Sea

    Science.gov (United States)

    Pearce, C.; O'Regan, M.; Rattray, J. E.; Hutchinson, D. K.; Cronin, T. M.; Gemery, L.; Barrientos, N.; Coxall, H.; Smittenberg, R.; Semiletov, I. P.; Jakobsson, M.

    2017-12-01

    Sea ice in the Arctic Ocean has been in steady decline in recent decades and, based on satellite data, the retreat is most pronounced in the Chukchi and Beaufort seas. Historical observations suggest that the recent changes were unprecedented during the last 150 years, but for a longer time perspective, we rely on the geological record. For this study, we analyzed sediment samples from two piston cores from Herald Canyon in the Chukchi Sea, collected during the 2014 SWERUS-C3 Arctic Ocean Expedition. The Herald Canyon is a local depression across the Chukchi Shelf, and acts as one of the main pathways for Pacific Water to the Arctic Ocean after entering through the narrow and shallow Bering Strait. The study site lies at the modern-day seasonal sea ice minimum edge, and is thus an ideal location for the reconstruction of past sea ice variability. Both sediment cores contain late Holocene deposits characterized by high sediment accumulation rates (100-300 cm/kyr). Core 2-PC1 from the shallow canyon flank (57 m water depth) is 8 meter long and extends back to 4200 cal yrs BP, while the upper 3 meters of Core 4-PC1 from the central canyon (120 mwd) cover the last 3000 years. The chronologies of the cores are based on radiocarbon dates and the 3.6 ka Aniakchak CFE II tephra, which is used as an absolute age marker to calculate the marine radiocarbon reservoir age. Analysis of biomarkers for sea ice and surface water productivity indicate stable sea ice conditions throughout the entire late Holocene, ending with an abrupt increase of phytoplankton sterols in the very top of both sediment sequences. The shift is accompanied by a sudden increase in coarse sediments (> 125 µm) and a minor change in δ13Corg. We interpret this transition in the top sediments as a community turnover in primary producers from sea ice to open water biota. Most importantly, our results indicate that the ongoing rapid ice retreat in the Chukchi Sea of recent decades was unprecedented during the

  4. Impact of roof height non-uniformity on pollutant transport between a street canyon and intersections.

    Science.gov (United States)

    Nosek, Štěpán; Kukačka, Libor; Jurčáková, Klára; Kellnerová, Radka; Jaňour, Zbyněk

    2017-08-01

    This paper presents an extension of our previous wind-tunnel study (Nosek et al., 2016) in which we highlighted the need for investigation of the removal mechanisms of traffic pollution from all openings of a 3D street canyon. The extension represents the pollution flux (turbulent and advective) measurements at the lateral openings of three different 3D street canyons for the winds perpendicular and oblique to the along-canyon axis. The pollution was simulated by emitting a passive gas (ethane) from a homogeneous ground-level line source positioned along the centreline of the investigated street canyons. The street canyons were formed by courtyard-type buildings of two different regular urban-array models. The first model has a uniform building roof height, while the second model has a non-uniform roof height along each building's wall. The mean flow and concentration fields at the canyons' lateral openings confirm the findings of other studies that the buildings' roof-height variability at the intersections plays an important role in the dispersion of the traffic pollutants within the canyons. For the perpendicular wind, the non-uniform roof-height canyon appreciably removes or entrains the pollutant through its lateral openings, contrary to the uniform canyon, where the pollutant was removed primarily through the top. The analysis of the turbulent mass transport revealed that the coherent flow structures of the lateral momentum transport correlate with the ventilation processes at the lateral openings of all studied canyons. These flow structures coincide at the same areas and hence simultaneously transport the pollutant in opposite directions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Computer-aided performance monitoring program at Diablo Canyon

    International Nuclear Information System (INIS)

    Nelson, T.; Glynn, R. III; Kessler, T.C.

    1992-01-01

    This paper describes the thermal performance monitoring program at Pacific Gas ampersand Electric Company's (PG ampersand E's) Diablo Canyon Nuclear Power Plant. The plant performance monitoring program at Diablo Canyon uses the THERMAC performance monitoring and analysis computer software provided by Expert-EASE Systems. THERMAC is used to collect performance data from the plant process computers, condition that data to adjust for measurement errors and missing data points, evaluate cycle and component-level performance, archive the data for trend analysis and generate performance reports. The current status of the program is that, after a fair amount of open-quotes tuningclose quotes of the basic open-quotes thermal kitclose quotes models provided with the initial THERMAC installation, we have successfully baselined both units to cycle isolation test data from previous reload cycles. Over the course of the past few months, we have accumulated enough data to generate meaningful performance trends and, as a result, have been able to use THERMAC to track a condenser fouling problem that was costing enough megawatts to attract corporate-level attention. Trends from THERMAC clearly related the megawatt loss to a steadily degrading condenser cleanliness factor and verified the subsequent gain in megawatts after the condenser was cleaned. In the future, we expect to rebaseline THERMAC to a beginning of cycle (BOC) data set and to use the program to help track feedwater nozzle fouling

  6. Following the canyon to reach and remove olfactory groove meningiomas.

    Science.gov (United States)

    Stefini, Roberto; Zenga, Francesco; Giacomo, Esposito; Bolzoni, Andrea; Tartara, Fulvio; Spena, Giannantonio; Ambrosi, Claudia; Fontanella, Marco M

    2017-04-01

    Olfactory groove meningiomas (OGMs) represent approximately 10% of all intracranial meningiomas. They arise in the olfactory fossa, a variable depression delimited by the lateral lamella and perpendicular plate. The cribriform plate with the lateral lamella and ethmoidal and orbital roof could be viewed as a 'canyon' with the frontal sinus as the main entrance. Between January 2000 and December 2013, 32 consecutive patients underwent removal of OGMs through this 'canyon' at the Department of Neurosurgery of Brescia and Turin. Complete removal was achieved in all patients with this trans-frontal sinus subcranial approach (Simpson grade I; mean lesion volume, 46.6 cm3). Five patients (15.6%) experienced nasal CSF leakage, treated with external lumbar drain positioning for 4 days and resolved in all cases but one, which was re-operated. Two patients (6.2%) during the CSF leakage experienced meningitis at day 7 after surgery, both successfully treated by intravenous antibiotic therapy. After one month, one patient developed hydrocephalus, treated with a ventricular peritoneal shunt. In one patient, traction on the OGM caused bleeding of the callosomarginal artery, which was coagulated with superior frontal gyrus ischemia without neurological consequences. Glasgow Outcome Scale Score at 6 months was V in 29 patients, IV in one patient, and I in two patients. Advantages with this approach may include easy and early control of blood supply from its insertion in the skull base, minimal frontal lobe retraction, preservation of the frontal veins draining to the sagittal sinus, and a satisfactory aesthetic outcome.

  7. An Improved Simulation of the Diurnally Varying Street Canyon Flow

    Science.gov (United States)

    Yaghoobian, Neda; Kleissl, Jan; Paw U, Kyaw Tha

    2012-11-01

    The impact of diurnal variation of temperature distribution over building and ground surfaces on the wind flow and scalar transport in street canyons is numerically investigated using the PArallelized LES Model (PALM). The Temperature of Urban Facets Indoor-Outdoor Building Energy Simulator (TUF-IOBES) is used for predicting urban surface heat fluxes as boundary conditions for a modified version of PALM. TUF-IOBES dynamically simulates indoor and outdoor building surface temperatures and heat fluxes in an urban area taking into account weather conditions, indoor heat sources, building and urban material properties, composition of the building envelope (e.g. windows, insulation), and HVAC equipment. Temperature (and heat flux) distribution over urban surfaces of the 3-D raster-type geometry of TUF-IOBES makes it possible to provide realistic, high resolution boundary conditions for the numerical simulation of flow and scalar transport in an urban canopy. Compared to some previous analyses using uniformly distributed thermal forcing associated with urban surfaces, the present analysis shows that resolving non-uniform thermal forcings can provide more detailed and realistic patterns of the local air flow and pollutant dispersion in urban canyons.

  8. Predictive Temperature Equations for Three Sites at the Grand Canyon

    Science.gov (United States)

    McLaughlin, Katrina Marie Neitzel

    Climate data collected at a number of automated weather stations were used to create a series of predictive equations spanning from December 2009 to May 2010 in order to better predict the temperatures along hiking trails within the Grand Canyon. The central focus of this project is how atmospheric variables interact and can be combined to predict the weather in the Grand Canyon at the Indian Gardens, Phantom Ranch, and Bright Angel sites. Through the use of statistical analysis software and data regression, predictive equations were determined. The predictive equations are simple or multivariable best fits that reflect the curvilinear nature of the data. With data analysis software curves resulting from the predictive equations were plotted along with the observed data. Each equation's reduced chi2 was determined to aid the visual examination of the predictive equations' ability to reproduce the observed data. From this information an equation or pair of equations was determined to be the best of the predictive equations. Although a best predictive equation for each month and season was determined for each site, future work may refine equations to result in a more accurate predictive equation.

  9. Actinide speciation in the shallow aquifer of Mortandad Canyon

    International Nuclear Information System (INIS)

    Nelson, D.M.; Polzer, W.L.

    1983-01-01

    Treated waste effluent at Los Alamos has been released to the environment in Mortandad Canyon since 1963. A study has been initiated to investigate the relative mobilities of the actinides in the shallow aquifer of Mortandad Canyon. Speciation of radionuclides and their adsorption by sediment are important parameters in the evaluation of those mobilities. Plutonium concentrations and oxidation states were measured in water collected from four test wells (MCO 4, 5, 6, 7.5). A regular decrease in 239 240 Pu concentration was observed with increasing distance from the discharge point. The large difference between the concentrations discharged (30 to 1000 pCi/l for period 1977-1982) and those in the wells (0.02 to 5.4 pCi/l) suggests that progressive loss of plutonium from the water as it moves through the alluvium is probably more important in regulating the concentrations than the variability of concentrations in the discharged effluent. The K/sub D/s for 228 Th were also determined and found to be similar to those for plutonium. The factors regulating the concentration of dissolved plutonium are probably the same as those regulating 228 Th. In contrast the K/sub D/s of 241 Am decrease regularly with distance from the discharge point and are about 100 times lower than those of plutonium and thorium for water in wells farthest from the discharge point

  10. A sand budget for Marble Canyon, Arizona: implications for long-term monitoring of sand storage change

    Science.gov (United States)

    Grams, Paul E.

    2013-01-01

    Recent U.S. Geological Survey research is providing important insights into how best to monitor changes in the amount of tributary-derived sand stored on the bed of the Colorado River and in eddies in Marble Canyon, Arizona. Before the construction of Glen Canyon Dam and other dams upstream, sandbars in Glen, Marble, and Grand Canyons were replenished each year by sediment-rich floods. Sand input into the Colorado River is crucial to protecting endangered native fish, animals, and plants and cultural and recreational resources along the river in Glen Canyon National Recreation Area and Grand Canyon National Park.

  11. Megafauna of vulnerable marine ecosystems in French mediterranean submarine canyons: Spatial distribution and anthropogenic impacts

    Science.gov (United States)

    Fabri, M.-C.; Pedel, L.; Beuck, L.; Galgani, F.; Hebbeln, D.; Freiwald, A.

    2014-06-01

    Vulnerable Marine Ecosystems (VME) in the deep Mediterranean Sea have been identified by the General Fisheries Commission for the Mediterranean as consisting of communities of Scleractinia (Lophelia pertusa and Madrepora oculata), Pennatulacea (Funiculina quadrangularis) and Alcyonacea (Isidella elongata). This paper deals with video data recorded in the heads of French Mediterranean canyons. Quantitative observations were extracted from 101 video films recorded during the MEDSEACAN cruise in 2009 (Aamp/Comex). Qualitative information was extracted from four other cruises (two Marum/Comex cruises in 2009 and 2011 and two Ifremer cruises in 1995 and 2010) to support the previous observations in the Cassidaigne and Lacaze-Duthiers canyons. All the species, fishing impacts and litter recognized in the video films recorded from 180 to 700 m depth were mapped using GIS. The abundances and distributions of benthic fishing resources (marketable fishes, Aristeidae, Octopodidae), Vulnerable Marine Species, trawling scars and litter of 17 canyons were calculated and compared, as was the open slope between the Stoechades and Toulon canyons. Funiculina quadrangularis was rarely observed, being confined for the most part to the Marti canyon and, I. elongata was abundant in three canyons (Bourcart, Marti, Petit-Rhône). These two cnidarians were encountered in relatively low abundances, and it may be that they have been swept away by repeated trawling. The Lacaze-Duthiers and Cassidaigne canyons comprised the highest densities and largest colony sizes of scleractinian cold-water corals, whose distribution was mapped in detail. These colonies were often seen to be entangled in fishing lines. The alcyonacean Callogorgia verticillata was observed to be highly abundant in the Bourcart canyon and less abundant in several other canyons. This alcyonacean was also severely affected by bottom fishing gears and is proposed as a Vulnerable Marine Species. Our studies on anthropogenic

  12. Laboratory study of fracture healing in Topopah Spring tuff: Implications for near field hydrology

    International Nuclear Information System (INIS)

    Lin, Wunan; Daily, W.D.

    1989-09-01

    Seven Topopah Spring tuff samples were studied to determine water permeability in this rock under pressure and temperature conditions similar to those expected in the near field of a nuclear waste package. Six of the seven samples were studied under isothermal condition; the other was subjected to a thermal gradient. Four of the six fractured samples contained a reopened, healed, natural fracture; one contained an induced tensile fracture and the other contained a saw-cut. The fracture surfaces were examined using scanning electron microscope (SEM) before and after the experiments and the water that flowed through the samples was sampled for chemical analysis. The experimental durations ranged from about 3 months to almost 6 months. Water permeability of the fractured samples was found to decrease by more than three orders of magnitude when the sample temperature increased to 150 degree C. The sharpest decrease in permeability occurred when the temperature was increased above 90 degree C. Permeability of the intact sample did not change significantly under the similar experimental conditions. When the temperature returned to room conditions, the water permeability did not recover. The mechanical strength of one healed sample was about half that of the intact rock. SEM studies of the fracture surfaces and water chemical analysis of the water suggested that both dissolution and deposition occurred on the fracture surfaces. Smoothing of fracture asperities because of dissolution and deposition was probably the main cause of the permeability decrease. Deposition of dissolved silica was probably the main cause of fracture healing. 12 refs., 6 figs., 1 tab

  13. Leaching Tc-99 from SRP glass in simulated tuff and salt groundwaters

    International Nuclear Information System (INIS)

    Bibler, N.E.; Jurgensen, A.R.

    1987-01-01

    Results of leach tests with Tc-99 doped SRP borosilicate waste glass are presented. The glass was prepared by melting a mixture of SRP 165 powdered frit doped with a carrier free solution of Tc-99 at 1150 0 C. Dissolution of portions of the resulting glass indicated that the Tc-99 was distributed homogeneously throughout the glass. Static leach tests up to 90 days were performed at 90 0 C in J-13 tuff groundwater or WIPP brine A at a SA/V of 100m -1 . Normalized mass losses were calculated for Tc-99 as well as all the major elements in the glass. Results indicated that under ambient oxidizing conditions Tc-99 leached no faster than the glass-forming elements of the glass. In J-13 water, Tc-99 leached congruently with B. In WIPP brine A, it leached congruently with Si. Leach rates for Li were higher in both groundwaters, probably due to a contribution from an ion exchange mechanism. Leach tests were performed under reducing conditions in J-13 water by adding Zn/Hg amalgam to the leachate. In these tests the pH increased significantly, probably because of the reaction of the amalgam with the water. In a 21-day test, the pH increased to 13 and leach rates for the glass were very high. Even though there was signifcant dissolution of the glass, the normalized mass loss based on Tc-99 was only 0.02g/m 2 . This result and the fact that reducing conditions at normal pH values do not significantly affect the dissolution of the glass, indicate that the low concentrations for Tc-99 obtained under reducing conditions are due to is solubility and not due to an increased durability of the glass. 14 refs., 2 figs., 5 tabs

  14. Measurements of matric and water potentials in unsaturated tuff at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Thamir, F.; McBride, C.M.

    1985-01-01

    Two types of instruments were installed in a borehole in order to monitor matric and water potentials of various hydrogeologic units consisting of tuff. The borehole was drilled as part of a study to provide information to the US Department of Energy for their use in evaluating Yucca Mountain, Nevada, for a repository for high-level radioactive waste. Heat-dissipation probes were used to monitor matric potentials and thermocouple psychrometers were used to monitor water potentials. Two major concerns regarding the use of these instruments in deep boreholes are: (1) the effect of length of the lead wires, and (2) the inability to recalibrate the instruments after installation. The length of the lead wire contributes to the source resistance and lead capacitance, which affects the signal settling time. Both instruments tested proved to be insensitive to lead-wire length, except when connected to smaller input-impedance data loggers. Thermocouple wires were more sensitive than heat-dissipation probe wires because of their greater resistance and quality of voltmeters used. Two thermocouple psychrometers were installed at every instrument station for backup and verification of data, because the instruments could not be recalibrated in situ. Multiple scanning rather than single-point scanning of the evaporation curve of a thermocouple psychrometer could give more reliable data, especially in differentiating between very wet and very dry environments. An isolated power supply needs to be used for each heat dissipation probe rather than a single power supply for a group of probes to avoid losing data from all probes when one probe malfunctions. This type of system is particularly desirable if the site is unattended by an operator for as long as a month. 20 refs., 13 figs., 2 tabs

  15. Hydrologic mechanisms governing fluid flow in partially saturated, fractured, porous tuff at Yucca Mountain

    International Nuclear Information System (INIS)

    Wang, J.S.Y.; Narasimhan, T.N.

    1984-10-01

    In contrast to the saturated zone where fluid moves rapidly along fractures, the fractures (with apertures large relative to the size of matrix pores) will desaturate first during drainage process and the bulk of fluid flow would be through interconnected pores in the matrix. Within a partially drained fracture, the presence of a relatively continuous air phase will produce practically an infinite resistance to liquid flow in the direction parallel to the fracture. The residual liquid will be held by capillary force in regions around fracture contact areas where the apertures are small. Normal to the fracture surfaces, the drained portion of the fractures will reduce the effective area for liquid flow from one matrix block to another matrix block. A general statistical theory is constructed for flow along the fracture and for flow between the matrix blocks to the fractures under partially saturated conditions. Results are obtained from an aperture distribution model for fracture saturation, hydraulic conductivity, and effective matrix-fracture flow areas as functions of pressure. Drainage from a fractured tuff column is simulated. The parameters for the simulations are deduced from fracture surface characteristics, spacings and orientations based on core analyses, and from matrix characteristics curve based on laboratory measurements. From the cases simulated for the fractured, porous column with discrete vertical and horizontal fractures and porous matrix blocks explicitly taken into account, it is observed that the highly transient changes from fully saturated conditions to partially saturated conditions are extremely sensitive to the fracture properties. However, the quasi-steady changes of the fluid flow of a partially saturated, fractured, porous system could be approximately simulated without taking the fractures into account. 22 references, 16 figures

  16. Radionuclide release from PWR fuels in a reference tuff repository groundwater

    International Nuclear Information System (INIS)

    Wilson, C.N.; Oversby, V.M.

    1985-03-01

    The Nevada Nuclear Waste Storage Investigations Project (NNWSI) is studying the suitability of the welded devitrified Topopah Spring tuff at Yucca Mountain, Nye County, Nevada, for potential use as a high-level nuclear waste repository. In support of the Waste Package task of NNWSI, tests have been conducted under ambient air environment to measure radionuclide release from two pressurized water reactor (PWR) spent fuels in water obtained from the J-13 well near the Yucca Mountain site. Four specimen types, representing a range of fuel physical conditions that may exist in a failed waste canister containing a limited amount of water were tested. The specimen types were: fuel rod sections split open to expose bare fuel particles; rod sections with water-tight end fittings with a 2.5-cm long by 150-μm wide slit through the cladding; rod sections with water-tight end fittings and two 200-μm-diameter holes through the cladding; and undefected rod segments with water-tight end fittings. Radionuclide release results from the first 223-day test runs on H.B. Robinson spent fuel specimens in J-13 water are reported and compared to results from a previous test series in which similar Turkey Point reactor spent fuel specimens were tested on deionized water. Selected initial results are also given for Turkey Point fuel specimens tested on J-13 water. Results suggest that the actinides Pu, Am, Cm and Np are released congruently with U as the UO 2 spent fuel matrix dissolves. Fractional release of 137 Cs and 99 Tc was greater than that measured for the actinides. Generally, lower radionuclide releases were measured for the H.B. Robinson fuel in J-13 water than for Turkey Point Fuel in deionized water. 8 references, 7 figures, 9 tables

  17. CONTACT ANGLE OF YUCCA MOUNTAIN WELDED TUFF WITH WATER AND BRINES

    International Nuclear Information System (INIS)

    H. Kalia

    2006-01-01

    A number of tests were performed to acquire contact angles between Yucca Mountain welded tuff from Topopah Springs Lower Lithophysal geologic unit and various brine solutions. The tests were performed on core disks received from Sample Management Facility (SMF), oven dried to a constant weight and the core disks vacuum saturated in: distilled water, J-13 water, calcium chloride brine and sodium chloride brine to constant weight. The contact angles were acquired from eight points on the surface of the core disks, four on rough surface, and four on polished surface. The contact angle was measured by placing a droplet of the test fluid, distilled water, J-13 water, calcium chloride brine and sodium chloride brine on the core disks. The objective of this test was to acquire contact angles as a potential input to estimating capillary forces in accumulated dust on the waste packages and drip shields slated for the proposed High-Level Radioactive Waste Repository at Yucca Mountain, Nevada. It was noted that once the droplet contacts the test surface, it continues to spread hence the contact angle continues to decrease with elapsed time. The maximum observed angle was at time 0 or when the drop contacted the rock surface. The measured contact angle, in all cases has significant scatter. In general, the time zero contact angles for core disks saturated in sodium chloride brine were smaller than those saturated in calcium chloride brine, distilled water, and J-13 water. The contact angles for samples saturated in distilled water, J-13 water and calcium chloride brine at time zero were similar. There was slight difference between the observed contact angles for smooth and rough surface of the test samples. The contact angles for smooth surfaces were smaller than for the rough surfaces

  18. Palaeomagnetism of lower cretaceous tuffs from Yukon-Kuskokwim delta region, western Alaska

    Science.gov (United States)

    Globerman, B.R.; Coe, R.S.; Hoare, J.M.; Decker, J.

    1983-01-01

    During the past decade, the prescient arguments1-3 for the allochthoneity of large portions of southern Alaska have been corroborated by detailed geological and palaeomagnetic studies in south-central Alaska 4-9 the Alaska Peninsula10, Kodiak Island11,12 and the Prince William Sound area13 (Fig. 1). These investigations have demonstrated sizeable northward displacements for rocks of late Palaeozoic, Mesozoic, and early Tertiary age in those regions, with northward motion at times culminating in collision of the allochthonous terranes against the backstop of 'nuclear' Alaska14,15. A fundamental question is which parts of Alaska underwent significantly less latitudinal translation relative to the 'stable' North American continent, thereby serving as the 'accretionary nucleus' into which the displaced 'microplates'16 were eventually incorporated17,18? Here we present new palaeomagnetic results from tuffs and associated volcaniclastic rocks of early Cretaceous age from the Yukon-Kuskokwin delta region in western Alaska. These rocks were probably overprinted during the Cretaceous long normal polarity interval, although a remagnetization event as recent as Palaeocene cannot be ruled out. This overprint direction is not appreciably discordant from the expected late Cretaceous direction for cratonal North America. The implied absence of appreciable northward displacement for this region is consistent with the general late Mesozoic-early Tertiary tectonic pattern for Alaska, based on more definitive studies: little to no poleward displacement for central Alaska, though substantially more northward drift for the 'southern Alaska terranes' (comprising Alaska Peninsula, Kodiak Island, Prince William Sound area, and Matunuska Valley) since late Cretaceous to Palaeocene time. ?? 1983 Nature Publishing Group.

  19. A strategy to seal exploratory boreholes in unsaturated tuff; Yucca Mountain Site Characterization Project

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, J.A. [Sandia National Labs., Albuquerque, NM (United States); Case, J.B.; Givens, C.A.; Carney, B.C. [IT Corp., Albuquerque, NM (United States)

    1994-04-01

    This report presents a strategy for sealing exploratory boreholes associated with the Yucca Mountain Site Characterization Project. Over 500 existing and proposed boreholes have been considered in the development of this strategy, ranging from shallow (penetrating into alluvium only) to deep (penetrating into the groundwater table). Among the comprehensive list of recommendations are the following: Those boreholes within the potential repository boundary and penetrating through the potential repository horizon are the most significant boreholes from a performance standpoint and should be sealed. Shallow boreholes are comparatively insignificant and require only nominal sealing. The primary areas in which to place seals are away from high-temperature zones at a distance from the potential repository horizon in the Paintbrush nonwelded tuff and the upper portion of the Topopah Spring Member and in the tuffaceous beds of the Calico Hills Unit. Seals should be placed prior to waste emplacement. Performance goals for borehole seals both above and below the potential repository are proposed. Detailed construction information on the boreholes that could be used for future design specifications is provided along with a description of the environmental setting, i.e., the geology, hydrology, and the in situ and thermal stress states. A borehole classification scheme based on the condition of the borehole wall in different tuffaceous units is also proposed. In addition, calculations are presented to assess the significance of the boreholes acting as preferential pathways for the release of radionuclides. Design calculations are presented to answer the concerns of when, where, and how to seal. As part of the strategy development, available technologies to seal exploratory boreholes (including casing removal, borehole wall reconditioning, and seal emplacement) are reviewed.

  20. Zircon crystallization and recycling in the magma chamber of the rhyolitic Kos Plateau Tuff (Aegean arc)

    Science.gov (United States)

    Bachman, O.; Charlier, B.L.A.; Lowenstern, J. B.

    2007-01-01

    In contrast to most large-volume silicic magmas in continental arcs, which are thought to evolve as open systems with significant assimilation of preexisting crust, the Kos Plateau Tuff magma formed dominantly by crystal fractionation of mafic parents. Deposits from this ~60 km3 pyroclastic eruption (the largest known in the Aegean arc) lack xenocrystic zircons [secondary ion mass spectrometry (SIMS) U-Pb ages on zircon cores never older than 500 ka] and display Sr-Nd whole-rock isotopic ratios within the range of European mantle in an area with exposed Paleozoic and Tertiary continental crust; this evidence implies a nearly closed-system chemical differentiation. Consequently, the age range provided by zircon SIMS U-Th-Pb dating is a reliable indicator of the duration of assembly and longevity of the silicic magma body above its solidus. The age distribution from 160 ka (age of eruption by sanidine 40Ar/39Ar dating; Smith et al., 1996) to ca. 500 ka combined with textural characteristics (high crystal content, corrosion of most anhydrous phenocrysts, but stability of hydrous phases) suggest (1) a protracted residence in the crust as a crystal mush and (2) rejuvenation (reduced crystallization and even partial resorption of minerals) prior to eruption probably induced by new influx of heat (and volatiles). This extended evolution chemically isolated from the surrounding crust is a likely consequence of the regional geodynamics because the thinned Aegean microplate acts as a refractory container for magmas in the dying Aegean subduction zone (continent-continent subduction).

  1. Pressurized Slot Testing to Determine Thermo-Mechanical Properties of Lithophysal Tuff at Yucca Mountain Nevada.

    Energy Technology Data Exchange (ETDEWEB)

    George, James T.; Sobolik, Steven R.; Lee, Moo Y.; Park, Byoung; Costin, Laurence

    2018-05-01

    The study described in this report involves heated and unheated pressurized slot testing to determine thermo-mechanical properties of the Tptpll (Tertiary, Paintbrush, Topopah Spring Tuff Formation, crystal poor, lower lithophysal) and Tptpul (upper lithophysal) lithostratigraphic units at Yucca Mountain, Nevada. A large volume fraction of the proposed repository at Yucca Mountain may reside in the Tptpll lithostratigraphic unit. This unit is characterized by voids, or lithophysae, which range in size from centimeters to meters, making a field program an effective method of measuring bulk thermal-mechanical rock properties (thermal expansion, rock mass modulus, compressive strength, time-dependent deformation) over a range of temperature and rock conditions. The field tests outlined in this report provide data for the determination of thermo-mechanical properties of this unit. Rock-mass response data collected during this field test will reduce the uncertainty in key thermal-mechanical modeling parameters (rock-mass modulus, strength and thermal expansion) for the Tptpll lithostratigraphic unit, and provide a basis for understanding thermal-mechanical behavior of this unit. The measurements will be used to evaluate numerical models of the thermal-mechanical response of the repository. These numerical models are then used to predict pre- and post-closure repository response. ACKNOWLEDGEMENTS The authors would like to thank David Bronowski, Ronnie Taylor, Ray E. Finley, Cliff Howard, Michael Schuhen (all SNL) and Fred Homuth (LANL) for their work in the planning and implementation of the tests described in this report. This is a reprint of SAND2004-2703, which was originally printed in July 2004. At that time, it was printed for a restricted audience. It has now been approved for unlimited release.

  2. Thermocouple psychrometer measurements of in situ water potential changes in heated welded tuff

    International Nuclear Information System (INIS)

    Mao, Nai-hsien; Wang, H.F.

    1991-05-01

    Ten thermocouple psychrometers (TCPs) to measure water potential (WP) were installed in three holes in G-Tunnel at the Nevada Test Site as part of the Prototype Engineered Barrier System Field Tests. These integrated tests measured several parameters as a function of location and time within a few meters of a heater emplaced in welded tuff. The primary goal of the TCP experiment was to find out whether the combination of laboratory calibration and field use of the TCP can provide useful data for determining the change of moisture condition in the field. We calibrated the TCPs in NaCl solutions up to 80 degree C(176 degree F) in the laboratory. In two holes, we used rubber sleeves and packers to house TCPs, and in the third hole, we used foam. All three holes were grouted behind the TCP assemblages. Field results of the heater test showed that small temperature gradients were present for all measurements. Nevertheless, the WP calibration made the necessary correction for the nonisothermal condition. A drying and re-wetting cycle peaked at about day 140 with a WP of -65 bar in borehole P3, located below the heater. A similar cycle but reduced in scale was found at about day 175 with a WP of -45 bar in borehole P2, above the heater. This difference in drying behavior above and below the heater was also observed from neutron data and was explained as a gravity effect. As temperatures increased, the evaporation rate of pore water increased, In unfractured rock, the gas-phase flow was primarily outward. Water condensed above the heater would drain back to keep the boiling region wet, but water condensed below the heater would drain away from the boiling region. This conceptual model explained both the time and magnitude differences for data from holes above and below the heater. 7 refs., 14 figs., 2 tabs

  3. Pollutant Concentrations in Street Canyons of Different Aspect Ratio with Avenues of Trees for Various Wind Directions

    Science.gov (United States)

    Gromke, Christof; Ruck, Bodo

    2012-07-01

    This study summarizes the effects of avenues of trees in urban street canyons on traffic pollutant dispersion. We describe various wind-tunnel experiments with different tree-avenue models in combination with variations in street-canyon aspect ratio W/ H (with W the street-canyon width and H the building height) and approaching wind direction. Compared to tree-free street canyons, in general, higher pollutant concentrations are found. Avenues of trees do not suppress canyon vortices, although the air ventilation in canyons is hindered significantly. For a perpendicular wind direction, increases in wall-average and wall-maximum concentrations at the leeward canyon wall and decreases in wall-average concentrations at the windward wall are found. For oblique and perpendicular wind directions, increases at both canyon walls are obtained. The strongest effects of avenues of trees on traffic pollutant dispersion are observed for oblique wind directions for which also the largest concentrations at the canyon walls are found. Thus, the prevailing assumption that attributes the most harmful dispersion conditions to a perpendicular wind direction does not hold for street canyons with avenues of trees. Furthermore, following dimensional analysis, an estimate of the normalized wall-maximum traffic pollutant concentration in street canyons with avenues of trees is derived.

  4. Fluctuating helical asymmetry and morphology of snails (Gastropoda in divergent microhabitats at 'Evolution Canyons I and II,' Israel.

    Directory of Open Access Journals (Sweden)

    Shmuel Raz

    Full Text Available Developmental instability of shelled gastropods is measured as deviations from a perfect equiangular (logarithmic spiral. We studied six species of gastropods at 'Evolution Canyons I and II' in Carmel and the Galilee Mountains, Israel, respectively. The xeric, south-facing, 'African' slopes and the mesic, north-facing, 'European' slopes have dramatically different microclimates and plant communities. Moreover, 'Evolution Canyon II' receives more rainfall than 'Evolution Canyon I.'We examined fluctuating asymmetry, rate of whorl expansion, shell height, and number of rotations of the body suture in six species of terrestrial snails from the two 'Evolution Canyons.' The xeric 'African' slope should be more stressful to land snails than the 'European' slope, and 'Evolution Canyon I' should be more stressful than 'Evolution Canyon II.' Only Eopolita protensa jebusitica showed marginally significant differences in fluctuating helical asymmetry between the two slopes. Contrary to expectations, asymmetry was marginally greater on the 'European' slope. Shells of Levantina spiriplana caesareana at 'Evolution Canyon I,' were smaller and more asymmetric than those at 'Evolution Canyon II.' Moreover, shell height and number of rotations of the suture were greater on the north-facing slopes of both canyons.Our data is consistent with a trade-off between drought resistance and thermoregulation in snails; Levantina was significantly smaller on the 'African' slope, for increasing surface area and thermoregulation, while Eopolita was larger on the 'African' slope, for reducing water evaporation. In addition, 'Evolution Canyon I' was more stressful than Evolution Canyon II' for Levantina.

  5. Contrasting perspectives on the Lava Creek Tuff eruption, Yellowstone, from new U-Pb and 40Ar/39Ar age determinations

    Science.gov (United States)

    Wilson, Colin J. N.; Stelten, Mark E.; Lowenstern, Jacob B.

    2018-06-01

    The youngest major caldera-forming event at Yellowstone was the 630-ka eruption of the Lava Creek Tuff. The tuff as mapped consists of two major ignimbrite packages (members A and B), linked to widespread coeval fall deposits and formation of the Yellowstone Caldera. Subsequent activity included emplacement of numerous rhyolite flows and domes, and development of two structurally resurgent domes (Mallard Lake and Sour Creek) that accommodate strain due to continual uplift/subsidence cycles. Uplifted lithologies previously mapped on and adjacent to Sour Creek dome were thought to include the 2.08-Ma Huckleberry Ridge Tuff, cropping out beneath Lava Creek Tuff members A and B. Mapped outcrops of this Huckleberry Ridge Tuff material were sampled as welded ignimbrite (sample YR345) on Sour Creek dome, and at nearby Bog Creek as welded ignimbrite (YR311) underlain by an indurated lithic lag breccia containing blocks of another welded ignimbrite (YR324). Zircon near-rim U-Pb analyses from these samples yield weighted mean ages of 661 ± 13 ka (YR345: 95% confidence), 655 ± 11 ka (YR311), and 664 ± 15 ka (YR324) (combined weighted mean of 658.8 ± 6.6 ka). We also studied two samples of ignimbrite previously mapped as Huckleberry Ridge Tuff on the northeastern perimeter of the Yellowstone Caldera, 12 km ENE of Sour Creek dome. Sanidines from these samples yield 40Ar/39Ar age estimates of 634.5 ± 6.8 ka (8YC-358) and 630.9 ± 4.1 ka (8YC-359). These age data show that all these units represent previously unrecognized parts of the Lava Creek Tuff and do not have any relationship to the Huckleberry Ridge Tuff. Our observations and data imply that the Lava Creek eruption was more complex than is currently assumed, incorporating two tuff units additional to those currently mapped, and which themselves are separated by a time break sufficient for cooling and some reworking. The presence of a lag breccia suggests that a source vent lay nearby (Caldera boundary in this area

  6. Contrasting perspectives on the Lava Creek Tuff eruption, Yellowstone, from new U–Pb and 40Ar/39Ar age determinations

    Science.gov (United States)

    Wilson, Colin J. N.; Stelten, Mark; Lowenstern, Jacob B.

    2018-01-01

    The youngest major caldera-forming event at Yellowstone was the ~ 630-ka eruption of the Lava Creek Tuff. The tuff as mapped consists of two major ignimbrite packages (members A and B), linked to widespread coeval fall deposits and formation of the Yellowstone Caldera. Subsequent activity included emplacement of numerous rhyolite flows and domes, and development of two structurally resurgent domes (Mallard Lake and Sour Creek) that accommodate strain due to continual uplift/subsidence cycles. Uplifted lithologies previously mapped on and adjacent to Sour Creek dome were thought to include the ~ 2.08-Ma Huckleberry Ridge Tuff, cropping out beneath Lava Creek Tuff members A and B. Mapped outcrops of this Huckleberry Ridge Tuff material were sampled as welded ignimbrite (sample YR345) on Sour Creek dome, and at nearby Bog Creek as welded ignimbrite (YR311) underlain by an indurated lithic lag breccia containing blocks of another welded ignimbrite (YR324). Zircon near-rim U–Pb analyses from these samples yield weighted mean ages of 661 ± 13 ka (YR345: 95% confidence), 655 ± 11 ka (YR311), and 664 ± 15 ka (YR324) (combined weighted mean of 658.8 ± 6.6 ka). We also studied two samples of ignimbrite previously mapped as Huckleberry Ridge Tuff on the northeastern perimeter of the Yellowstone Caldera, ~ 12 km ENE of Sour Creek dome. Sanidines from these samples yield 40Ar/39Ar age estimates of 634.5 ± 6.8 ka (8YC-358) and 630.9 ± 4.1 ka (8YC-359). These age data show that all these units represent previously unrecognized parts of the Lava Creek Tuff and do not have any relationship to the Huckleberry Ridge Tuff. Our observations and data imply that the Lava Creek eruption was more complex than is currently assumed, incorporating two tuff units additional to those currently mapped, and which themselves are separated by a time break sufficient for cooling and some reworking. The presence of a lag breccia suggests that a source

  7. Isotopegeochemical investigations and dating on minerals and fossils from sedimentary rocks: 1. Glauconites from Jura, Molasse and Helveticum (K-Ar, Rb-Sr), 2. 87Sr/86Sr-Isotope stratigraphy on marine and limnetic micro- and macro-fossils, 3. Primary minerals from tertiary bentonites and tuffs (U-Pb, K-Ar)

    International Nuclear Information System (INIS)

    Fischer, H.

    1988-01-01

    Glauconite investigations: the main problem in dating glauconites lies in the identification of authigenic minerals which have not been influenced by post-sedimentary processes. The age determination on glauconites from the three different tectonic units: the Jura mountains, the molasse basin and the Helvetic nappes, yield inconsistent results. Up to 35% too young K-Ar ''ages'' of glauconites from limestones from the Helvetic nappes can be traced to partial Ar loss caused by sediment-lithification and tectonic events. Sr-isotope stratigraphy: multiple analyses of recent samples from the Mediterranean Sea and from the North Atlantic show that the 87 Sr/ 86 Sr isotope ratios correspond well. In a stratigraphic ideal section from the Upper marine molasse a resolution of 206 Pb/ 238 U method zircons from the Fish Canyon Tuff were measured and yielded ages of 28.49±0.10, 24.46±0.11 and 28.46±0.13 Ma. These values correspond well with the published mean value of zircon and apatite fission track age of 28.4±0.7 Ma. Thus, the U-Pb method for dating young volcanic minerals seems to be suitable. However, the published mean value (''solid state age'') of Naeser et al. (1981) is higher than the published (''gas age'') mean value of 27.2±0.7 Ma based on biotite, sanidine, hornblende and plagioclase. (author) figs., tabs., refs

  8. Geomorphic Thresholds of Submarine Canyons Along the U.S. Atlantic Continental Margin

    Science.gov (United States)

    Brothers, D. S.; ten Brink, U. S.; Andrews, B. D.; Chaytor, J. D.

    2011-12-01

    Vast networks of submarine canyons and associated channels are incised into the U.S. Atlantic continental slope and rise. Submarine canyons form by differential erosion and deposition, primarily from sedimentary turbidity flows. Theoretical and laboratory studies have investigated the initiation of turbidity flows and their capacity to erode and entrain sedimentary material at distances far from the shelf edge. The results have helped understand the nature of turbidite deposits on the continental slope and rise. Nevertheless, few studies have examined the linkages between down-canyon sediment transport and the morphology of canyon/channel networks using mesoscale analyses of swath bathymetry data. We present quantitative analysis of 100-m resolution multibeam bathymetry data spanning ~616,000 km2 of the slope and rise between Georges Banks and the Blake Plateau (New England to North Carolina). Canyons are categorized as shelf-indenting or slope-confined based on spatial scale, vertical relief and connection with terrestrial river systems during sea level low stands. Shelf-indenting canyons usually represent the trunk-canyon of submerged channel networks. On the rise, shelf-indenting canyons have relatively well-developed channel-levees and sharp inner-thalwag incision suggesting much higher frequency and volume of turbidity flows. Because of the similarities between submarine canyon networks and terrestrial river systems, we apply methods originally developed to study fluvial morphology. Along-canyon profiles are extracted from the bathymetry data and the power-law relationship between thalwag gradient and drainage area is examined for more than 180 canyons along an ~1200 km stretch of the US Atlantic margin. We observe distinct thresholds in the power-law relationship between drainage area and gradient. Almost all canyons with heads on the upper slope contain at least two linear segments when plotted in log-log form. The first segment along the upper slope is flat

  9. Evaluation of turbulence from traffic using experimental data obtained in a street canyon

    Energy Technology Data Exchange (ETDEWEB)

    Mazzeo, N.A.; Venegas, L.E. [Univ. of Buenos Aires, Buenos Aires (Argentina). Dept. of Atmospheric and Oceanic Sciences, National Scientific and Technological Research Council

    2004-07-01

    High air pollution levels have been observed in street canyons. Within these streets, pedestrians, cyclists, drivers and residents are likely to be exposed to pollutant concentrations exceeding current air quality standards. Airflow and dispersion in street canyons are very complicated. Depending on the synoptic wind three main dispersion conditions can be identified: a) low wind conditions, b) perpendicular or near perpendicular flow for winds over 1.5-2.0 m/s blowing at an angle of more than 30 to the canyon axes, c) parallel or near parallel flow for winds over 1.5-2.0 m/s blowing from all other directions. Under condition b), airflow in canyons with H/W{approx}1 (H is the height and W is the width of the canyon) is characterised by the formation of a single vortex within the canyon. The dispersion of gaseous pollutants in a street canyon depends generally on the rate at which the street exchanges air vertically with the above roof-level atmosphere and laterally with connecting streets. There is evidence that when the synoptic wind speed is low, the mechanical traffic-produced turbulence (TPT) might place a significant role in dispersion of traffic-generated pollutants. In this paper, we analyse interactions between wind and traffic induced dispersive air motions. Data from full-scale measurements in Goettinger Strasse (Hannover, Germany) are used for application of parameterisation proposed by Di Sabatino, S. et al. (2003) and Kastner-Klein, P. et al. (2003). (orig.)

  10. Experimental simulation of air quality in street canyon under changes of building orientation and aspect ratio.

    Science.gov (United States)

    Yassin, Mohamed F; Ohba, Masaake

    2012-09-01

    To assist validation of numerical simulations of urban pollution, air quality in a street canyon was investigated using a wind tunnel as a research tool under neutral atmospheric conditions. We used tracer gas techniques from a line source without buoyancy. Ethylene (C(2)H(4)) was used as the tracer gas. The street canyon model was formed of six parallel building rows of the same length. The flow and dispersion field was analyzed and measured using a hot-wire anemometer with split fiber probe and fast flame ionization detector. The diffusion flow field in the boundary layer within the street canyon was examined at different locations, with varying building orientations (θ=90°, 112.5°, 135° and 157.5°) and street canyon aspect ratios (W/H=1/2, 3/4 and 1) downwind of the leeward side of the street canyon model. Results show that velocity increases with aspect ratio, and with θ>90°. Pollutant concentration increases as aspect ratio decreases. This concentration decreases exponentially in the vertical direction, and decreases as θ increases from 90°. Measured pollutant concentration distributions indicate that variability of building orientation and aspect ratio in the street canyon are important for estimating air quality in the canyon. The data presented here can be used as a comprehensive database for validation of numerical models.

  11. On the pollutant removal, dispersion, and entrainment over two-dimensional idealized street canyons

    Science.gov (United States)

    Liu, Chun-Ho; Wong, Colman C. C.

    2014-01-01

    Pollutant dispersion over urban areas is not that well understood, in particular at the street canyon scale. This study is therefore conceived to examine how urban morphology modifies the pollutant removal, dispersion, and entrainment over urban areas. An idealized computational domain consisting of 12 two-dimensional (2D) identical street canyons of unity aspect ratio is employed. The large-eddy simulation (LES) is used to calculate the turbulent flows and pollutant transport in the urban boundary layer (UBL). An area source of uniform pollutant concentration is applied on the ground of the first street canyon. A close examination on the roof-level turbulence reveals patches of low-speed air masses in the streamwise flows and narrow high-speed downdrafts in the shear layer. Different from the flows over a smooth surface, the turbulence intensities are peaked near the top of the building roughness. The pollutant is rather uniformly distributed inside a street canyon but disperses quickly in the UBL over the buildings. Partitioning the vertical pollutant flux into its mean and turbulent components demystifies that the pollutant removal is mainly governed by turbulence. Whereas, mean wind carries pollutant into and out of a street canyon simultaneously. In addition to wind speed promotion, turbulent mixing is thus required to dilute the ground-level pollutants, which are then removed from the street canyon to the UBL. Atmospheric flows slow down rapidly after the leeward buildings, leading to updrafts carrying pollutants away from the street canyons (the basic pollutant removal mechanism).

  12. Rapid formation of a modern bedrock canyon by a single flood event

    Science.gov (United States)

    Lamb, Michael P.; Fonstad, Mark A.

    2010-07-01

    Deep river canyons are thought to form slowly over geological time (see, for example, ref. 1), cut by moderate flows that reoccur every few years. In contrast, some of the most spectacular canyons on Earth and Mars were probably carved rapidly during ancient megaflood events. Quantification of the flood discharge, duration and erosion mechanics that operated during such events is hampered because we lack modern analogues. Canyon Lake Gorge, Texas, was carved in 2002 during a single catastrophic flood. The event offers a rare opportunity to analyse canyon formation and test palaeo-hydraulic-reconstruction techniques under known topographic and hydraulic conditions. Here we use digital topographic models and visible/near-infrared aerial images from before and after the flood, discharge measured during the event, field measurements and sediment-transport modelling to show that the flood moved metre-sized boulders, excavated ~7m of limestone and transformed a soil-mantled valley into a bedrock canyon in just ~3days. We find that canyon morphology is strongly dependent on rock type: plucking of limestone blocks produced waterfalls, inner channels and bedrock strath terraces, whereas abrasion of cemented alluvium sculpted walls, plunge pools and streamlined islands. Canyon formation was so rapid that erosion might have been limited by the ability of the flow to transport sediment. We suggest that our results might improve hydraulic reconstructions of similar megafloods on Earth and Mars.

  13. Modern landscape processes affecting archaeological sites along the Colorado River corridor downstream of Glen Canyon Dam, Glen Canyon National Recreation Area, Arizona

    Science.gov (United States)

    East, Amy E.; Sankey, Joel B.; Fairley, Helen C.; Caster, Joshua J.; Kasprak, Alan

    2017-08-29

    The landscape of the Colorado River through Glen Canyon National Recreation Area formed over many thousands of years and was modified substantially after the completion of Glen Canyon Dam in 1963. Changes to river flow, sediment supply, channel base level, lateral extent of sedimentary terraces, and vegetation in the post-dam era have modified the river-corridor landscape and have altered the effects of geologic processes that continue to shape the landscape and its cultural resources. The Glen Canyon reach of the Colorado River downstream of Glen Canyon Dam hosts many archaeological sites that are prone to erosion in this changing landscape. This study uses field evaluations from 2016 and aerial photographs from 1952, 1973, 1984, and 1996 to characterize changes in potential windblown sand supply and drainage configuration that have occurred over more than six decades at 54 archaeological sites in Glen Canyon and uppermost Marble Canyon. To assess landscape change at these sites, we use two complementary geomorphic classification systems. The first evaluates the potential for aeolian (windblown) transport of river-derived sand from the active river channel to higher elevation archaeological sites. The second identifies whether rills, gullies, or arroyos (that is, overland drainages that erode the ground surface) exist at the archaeological sites as well as the geomorphic surface, and therefore the relative base level, to which those flow paths drain. Results of these assessments are intended to aid in the management of irreplaceable archaeological resources by the National Park Service and stakeholders of the Glen Canyon Dam Adaptive Management Program.

  14. Facies and depositional model of Almada Canyon, Almada Basin, Bahia, Brazil; Facies e modelo deposicional do Canyon de Almada, Bacia de Almada, Bahia

    Energy Technology Data Exchange (ETDEWEB)

    D' Avila, Roberto Salvador Francisco; Souza Cruz, Carlos Emanoel de; Oliveira Filho, Jose Souto; Jesus, Candida Menezes de; Cesero, Pedro de; Dias Filho, Dorval Carvalho; Lima, Claudio Coelho de; Queiroz, Claudia Lima de; Santos, Saulo Ferreira; Ferreira, Eduardo Araripe [PETROBRAS, Santos, SP (Brazil). Unidade de Negocio de Exploracao]. E-mail: rdavila@petrobras.com.br

    2004-11-01

    In the continental portion of the Almada Basin outcrops of canyon filling deposits are represented by turbidite channels and associated facies from Urucutuca Formation. The canyon - semi-exhumated - eroded basement and pre-Cenomanian sedimentary rocks. The field study of the outcrops and cores obtained in adjacent perforations lead to the understanding of the facies and processes that controlled the deposition of these channeled turbidite that can be compared to the reservoirs of many oil fields in Brazil. The Almada canyon is a submarine conduct of tectonic origin that was enlarged by the repeated passing of turbidity currents. During the rift phase and the Albian period, compressive events reactivated old N E and N W faults in the basement as trans current fault systems. The continuation of these stresses, from the Cenomanian to the Maastrichtian, developed normal faults that controlled a submarine canyon that connected the continent, where an estuary was formed between the mountains, to the deep marine region of the basin. The canyon has received sediments brought by catastrophic fluvial floods coming from the surrounding mountains, which formed hyperpicnal flows that have evolved as turbidity currents, thus causing erosion of the substrate and carrying a huge volume of sediments to the basin. A part of that load was deposited in the canyon and formed turbidite channels filled by conglomerates, sandstones and shales. These moderately to highly efficient turbidite are intercalated to pro delta pelites and low density turbid plumes deposits, which have mostly been re mobilized as slump and debris flows (chaotic deposits). Pelites were accumulated mainly in the normal fluvial sedimentation phases, when the sandy sediment was retained next to the canyon head and were reworked by the tides on the upper part of the estuary. (author)

  15. Draft environmental assessment: Davis Canyon site, Utah. Nuclear Waste Policy Act (Section 112)

    International Nuclear Information System (INIS)

    1984-12-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah, as one of nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for Nuclear Waste Repositories. These evaluations are reported in this draft environmental assessment (EA), which is being issued for public review and comment. The DOE findings and determinations that are based on these evaluations are preliminary and subject to public review and comment. A final EA will be prepared after considering the comments received. On the basis of the evaluations reported in this draft EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. The site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site - the Lavender Canyon site. Although the Lavender Canyon site appears to be suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. Furthermore, the DOE finds that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is proposing to nominate the Davis Canyon site as one of five sites suitable for characterization. Having compared the Davis Canyon site with the other four sites proposed for nomination, the DOE has determined that the Davis Canyon site is not one of the three preferred sites for recommendation to the President as candidates for characterization

  16. Consideration of Nuclear Criticality When Directly Disposing Highly Enriched Spent Nuclear Fuel in Unsaturated Tuff - II: Geochemical Constraints

    International Nuclear Information System (INIS)

    Rechard, Rob P.; Sanchez, Lawrence C.; Trellue, Holly R.

    2003-01-01

    This article presents several reasonable cases in which four mechanisms - dissolution, physical mixing, adsorption, and precipitation (either chemical change or evaporation) - might concentrate fissile material in and around a disposal container for radioactive waste at the proposed repository at Yucca Mountain, Nevada. The possible masses, concentrations, and volume are then compared to criticality limits. The cases examined evaluate the geologic barrier role in preventing criticality since engineered options for preventing criticality (e.g., boron or gadolinium neutron absorber in the disposal container) are not considered. The solid concentrations able to form in the natural environment are insufficient for criticality to occur because (a) solutions of 235 U and 239 Pu are clearly not critical; (b) physical mixing of fissile material with the entire potential iron oxide (as goethite - FeOOH) in a waste package is not critical; (c) the adsorption of 239 Pu on consolidated iron oxide in a waste package is not critical; (d) the adsorption of 235 U on consolidated iron oxide in a waste package is not critical when accounting for reduced adsorption because of carbonates at high pH; (e) the filtration of iron oxide colloids, containing fissile material, by the thin invert material is not critical; (f) insufficient retention through precipitation of 235 U or 239 Pu occurs in the invert; (g) adsorption of 235 U and 239 Pu on devitrified or clinoptolite-rich tuff below the repository is not critical; (h) the average precipitation/adsorption of 235 U as uranyl silicates in the tuff is not critical by analogy with calcite deposition in lithophysae at Yucca Mountain; and (i) precipitation/adsorption (caused by cyclic drying) as uranyl silicates on fracture surfaces of the tuff is not critical by analogy with the oxidation of UO 2 , migration of U VI , and precipitation in fractures at the Nopal I ore deposit in Mexico

  17. Freeze-Thaw Cycle Test on Basalt, Diorite and Tuff Specimens with the Simulated Ground Temperature of Antarctica

    Science.gov (United States)

    Park, J.; Hyun, C.; Cho, H.; Park, H.

    2010-12-01

    Physical weathering caused by freeze-thaw action in cold regions was simulated with artificial weathering simulator in laboratory. Physical weathering of rock in cold regions usually depends on the temperature, rock type and moisture content. Then these three variables were considered in this study. The laboratory freeze-thaw tests were conducted on the three types of rocks, e.g. diorite, basalt and tuff, which are the major rock types around Sejong Station, King George Island, Antarctica. Nine core samples composed of three samples from each rock type were prepared in NX core, and 50 cycles of freeze-thaw test was carried out under dried and saturated water conditions. In this study, the physical weathering of rocks was investigated after each 10 cycles by measuring P-wave velocity, bulk density, effective porosity, Schmidt hardness and uniaxial compression strength(UCS). The experimental result of the diorite and the tuff specimens showed that P-wave velocity, bulk density, effective porosity, Schmidt hardness and UCS were gradually decreased as weathering progresses, but the result of the basalt specimens did not show typical trends due to the characteristics of irregular pore distribution and various pore sizes. Scanning electron microscopy(SEM) photographs of diorite, basalt and tuff specimens weathered in dried and saturated conditions were also acquired to investigate the role of water during physical weathering processes. The number and size of microcracks were increased as weathering progresses. This work was supported by the National Research Foundation of Korea(NRF) Grant(NRF-2010-0027753).

  18. Investigation of bacterial transport in the large-block test, a thermally perturbed block of Topopah Spring Tuff

    International Nuclear Information System (INIS)

    Chen, C. I.; Chuu, Y. J.; Lin, W.; Meike, A.; Sawvel, A.

    1998-01-01

    This study investigates the transport of bacteria in a large, thermally perturbed block of Topopah Spring tuff. The study was part of the Large-Block Test (LBT), thermochemical and physical studies conducted on a 10 ft x 10 ft x 14 ft block of volcanic tuff excavated on 5 of 6 sides out of Fran Ridge, Nevada. Two bacterial species, Bacillus subtilis and Arthrobacter oxydans, were isolated from the Yucca Mountain tuff. Natural mutants that can grow under the simultaneous presence of the two antibiotics, streptomycin and rifampicin, were selected from these species by laboratory procedures. The double-drug-resistant mutants, which could be thus distinguished from the indigenous species, were injected into the five heater boreholes of the large block hours before heating was initiated. The temperature, as measured 5 cm above one of the heater boreholes, rose slowly and steadily over a matter of months to a maximum of 142 C. Samples (cotton cloths inserted the length of the hole, glass fiber swabs, and filter papers) were collected from the boreholes that were approximately 5 ft below the injection points. Double-drug-resistant bacteria were found in the collection boreholes nine months after injection. Surprisingly, they also appeared in the heater boreholes where the temperature had been sustainably high throughout the test. These bacteria appear to be the species that were injected. The number of double-drug-resistant bacteria that were identified in the collection boreholes increased with time. An apparent homogeneous distribution among the observation boreholes and heater boreholes suggests that a random motion could be the pattern that the bacteria migrated in the block. These observations indicated the possibility of rapid bacterial transport in a thermally perturbed geologic setting

  19. Manganese-oxide minerals in fractures of the Crater Flat Tuff in drill core USW G-4, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Carlos, B.A.; Bish, D.L.; Chipera, S.J.

    1990-07-01

    The Crater Flat Tuff is almost entirely below the water table in drill hole USW G-4 at Yucca Mountain, Nevada. Manganese-oxide minerals from the Crater Flat Tuff in USW G-4 were studied using optical, scanning electron microscopic, electron microprobe, and x-ray powder diffraction methods to determine their distribution, mineralogy, and chemistry. Manganese-oxide minerals coat fractures in all three members of the Crater Flat Tuff (Prow Pass, Bullfrog, and Tram), but they are most abundant in fractures in the densely welded devitrified intervals of these members. The coatings are mostly of the cryptomelane/hollandite mineral group, but the chemistry of these coatings varies considerably. Some of the chemical variations, particularly the presence of calcium, sodium, and strontium, can be explained by admixture with todorokite, seen in some x-ray powder diffraction patterns. Other chemical variations, particularly between Ba and Pb, demonstrate that considerable substitution of Pb for Ba occurs in hollandite. Manganese-oxide coatings are common in the 10-m interval that produced 75% of the water pumped from USW G-4 in a flow survey in 1983. Their presence in water-producing zones suggests that manganese oxides may exert a significant chemical effect on groundwater beneath Yucca Mountain. In particular, the ability of the manganese oxides found at Yucca Mountain to be easily reduced suggests that they may affect the redox conditions of the groundwater and may oxidize dissolved or suspended species. Although the Mn oxides at Yucca Mountain have low exchange capacities, these minerals may retard the migration of some radionuclides, particularly the actinides, through scavenging and coprecipitation. 23 refs., 21 figs., 2 tabs

  20. Measurements of distribution coefficient for Sn, Pb and Th on sand stone and tuff in saline type groundwater

    International Nuclear Information System (INIS)

    Nakazawa, Toshiyuki; Okada, Kenichi; Muroi, Masayuki; Shibata, Masahiro; Sasamoto, Hiroshi

    2004-02-01

    Japan Nuclear Cycle Development Institute (JNC) has developed the sorption database for bentonite and rocks in order to assess the retardation capacities of important radioactive elements in natural and engineered barriers in the H12 report. However, there are not enough distribution coefficient data for radioactive elements in saline type groundwater in the database. Sn (tin), Pb (lead) and Th(thorium) are important radioactive elements for performance assessment of high level radioactive waste disposal, thus we carried out the batch sorption experiments for these radioactive elements on sand stone and tuff. The experiments for each radioactive element were performed on the following conditions; Sn: Kd measurements using the solutions (distilled water or artificial sea water) reacted with sand stone. Pb: Kd measurements using solution (artificial sea water) reacted with sand stone or tuff. Th: Kd measurements using solution (artificial sea water) reacted with sand stone as a function of carbonate concentration. The results of experiment are summarized below; In the case of Sn, Kd were 0.4-1 m 3 /kg in distilled water type and approximately 1 m 3 /kg in artificial sea water type. And also, Kd was 0.3 m 3 /kg in artificial sea water adjusted Ph 12. In artificial sea water type, it was suggested that Kd decreased with pH. In the case of Pb, Kd were approximately 2 m 3 /kg on sand stone and 4-10 m 3 /kg on tuff in artificial sea water type. Kd on tuff was a little larger than that on sand stone. There were no distinctly differences depending on solid-liquid separation methods. In the case of Th, Kd was approximately 1-8 m 3 /kg in artificial sea water type. On the other hand, sorption of Th on sand stone was not observed (i.e., Kd = 0 m 3 /kg) in high carbonate solution. It was estimated that low Kd in high carbonate solution might be caused by speciation of because Th could form the anions in the solution such as hydroxo-carbonate complexes and carbonate complexes

  1. Petrologic and geochemical characterization of the Topopah Spring Member of the Paintbrush Tuff: outcrop samples used in waste package experiments

    International Nuclear Information System (INIS)

    Knauss, K.G.

    1984-06-01

    This report summarizes characterization studies conducted with outcrop samples of Topopah Spring Member of the Paintbrush Tuff (Tpt). In support of the Waste Package Task within the Nevada Nuclear Waste Storage Investigation (NNWSI), Tpt is being studied both as a primary object and as a constituent used to condition water that will be reacted with waste form, canister, or packing material. These studies directly or indirectly support NNWSI subtasks concerned with waste package design and geochemical modeling. To interpret the results of subtask experiments, it is necessary to know the exact nature of the starting material in terms of the intial bulk composition, mineralogy, and individual phase geochemistry. 31 figures, 5 tables

  2. Numerical Simulation of Tuff Dissolution and Precipitation Experiments: Validation of Thermal-Hydrologic-Chemical (THC) Coupled-Process Modeling

    Science.gov (United States)

    Dobson, P. F.; Kneafsey, T. J.

    2001-12-01

    As part of an ongoing effort to evaluate THC effects on flow in fractured media, we performed a laboratory experiment and numerical simulations to investigate mineral dissolution and precipitation. To replicate mineral dissolution by condensate in fractured tuff, deionized water equilibrated with carbon dioxide was flowed for 1,500 hours through crushed Yucca Mountain tuff at 94° C. The reacted water was collected and sampled for major dissolved species, total alkalinity, electrical conductivity, and pH. The resulting steady-state fluid composition had a total dissolved solids content of about 140 mg/L; silica was the dominant dissolved constituent. A portion of the steady-state reacted water was flowed at 10.8 mL/hr into a 31.7-cm tall, 16.2-cm wide vertically oriented planar fracture with a hydraulic aperture of 31 microns in a block of welded Topopah Spring tuff that was maintained at 80° C at the top and 130° C at the bottom. The fracture began to seal within five days. A 1-D plug-flow model using the TOUGHREACT code developed at Berkeley Lab was used to simulate mineral dissolution, and a 2-D model was developed to simulate the flow of mineralized water through a planar fracture, where boiling conditions led to mineral precipitation. Predicted concentrations of the major dissolved constituents for the tuff dissolution were within a factor of 2 of the measured average steady-state compositions. The fracture-plugging simulations result in the precipitation of amorphous silica at the base of the boiling front, leading to a hundred-fold decrease in fracture permeability in less than 6 days, consistent with the laboratory experiment. These results help validate the use of the TOUGHREACT code for THC modeling of the Yucca Mountain system. The experiment and simulations indicate that boiling and concomitant precipitation of amorphous silica could cause significant reductions in fracture porosity and permeability on a local scale. The TOUGHREACT code will be used

  3. Petrologic and geochemical characterization of the Topopah Spring Member of the Paintbrush Tuff: outcrop samples used in waste package experiments

    Energy Technology Data Exchange (ETDEWEB)

    Knauss, K.G.

    1984-06-01

    This report summarizes characterization studies conducted with outcrop samples of Topopah Spring Member of the Paintbrush Tuff (Tpt). In support of the Waste Package Task within the Nevada Nuclear Waste Storage Investigation (NNWSI), Tpt is being studied both as a primary object and as a constituent used to condition water that will be reacted with waste form, canister, or packing material. These studies directly or indirectly support NNWSI subtasks concerned with waste package design and geochemical modeling. To interpret the results of subtask experiments, it is necessary to know the exact nature of the starting material in terms of the intial bulk composition, mineralogy, and individual phase geochemistry. 31 figures, 5 tables.

  4. Calculation of experiment uncertainty in laboratory determination of several geoengineering properties of tuffs from Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Nimick, F.B.; Schwartz, B.M.; Price, R.H.

    1991-11-01

    A method for estimating the precision and accuracy of measured parameters is described. Examples of application of the estimating method are presented for density, porosity, compressive strength, Young's modulus, Poisson's ratio, and thermal expansion. With the exception of the coefficient of linear thermal expansion, all laboratory data for these properties for tuff samples appear to have reasonable experiment uncertainties. Uncertainties in the thermal-expansion coefficients may be as high as 39% of the values, although most uncertainties for the coefficients are probably ≤2%. 4 refs., 1 fig., 15 tabs

  5. Geochronology, stratigraphy and geochemistry of Cindery Tuff in Pliocene hominid-bearing sediments of the Middle Awash, Ethiopia.

    Science.gov (United States)

    Hall, C M; Walter, R C; Westgate, J A; York, D

    Cindery Tuff is a subalkaline, rhyolitic air-fall deposit that was probably produced by a mixed-magma eruption. It is a distinctive, datable, regional isochronous marker bed within the Pliocene sediments of the Middle Awash district, and is stratigraphically situated between two new fossil hominid discoveries. Based on 40Ar/39Ar analyses of plagioclase, rhyolitic glass and basaltic glass, as well as fission-track analyses of zircons, we estimate its age to be 3.8-4.0 Myr. This implies that associated hominid skull fragments are at least 3.9 Myr old.

  6. The effect of temperature on the sorption of technetium, uranium, neptunium and curium on bentonite, tuff and granodiorite

    International Nuclear Information System (INIS)

    Baston, G.M.N.; Berry, J.A.; Brownsword, M.; Heath, T.G.; Ilett, D.J.; Tweed, C.J.; Yui, M.

    1997-01-01

    A study of the sorption of the radioelements technetium; uranium; neptunium; and curium onto geological materials has been carried out as part of the PNC program to increase confidence in the performance assessment for a high-level radioactive waste repository in Japan. Batch sorption experiments have been performed in order to study the sorption of the radioelements onto bentonite, tuff and granodiorite from equilibrated de-ionized water under strongly-reducing conditions at both room temperature and at 60 C. Mathematical modelling using the geochemical speciation program HARPHRQ in conjunction with the HATCHES database has been undertaken in order to interpret the experimental results

  7. Spatial variability of damage around faults in the Joe Lott Tuff Member of the Mount Belknap Volcanics, southwestern Utah

    Science.gov (United States)

    Okubo, C. H.

    2012-12-01

    In order to yield new insight into the process of faulting in fine-grained, poorly indurated volcanic ash, the distribution of strain around faults in the Miocene-aged Joe Lott Tuff Member of the Mount Belknap Volcanics, Utah, is investigated. Several distinct styles of inelastic strain are identified. Deformation bands are observed in tuff that is porous and granular in nature, or is inferred to have been so at the time of deformation. Where silicic alteration is pervasive, fractures are the dominant form of localized strain. Non-localized strain within the host rock is manifest as pore space compaction, including crushing of pumice clasts. Distinct differences in fault zone architecture are observed at different magnitudes of normal fault displacement, in the mode II orientation. A fault with cm-scale displacements is manifest as a single well-defined surface. Off-fault damage occurs as pore space compaction near the fault tips and formation of deformation band damage zones that are roughly symmetric about the fault. At a fault with larger meter-scale displacements, a fault core is present. A recognizable fault-related deformation band damage zone is not observed here, even though large areas of the host rock remain porous and granular and deformation bands had formed prior to faulting. The host rock is instead fractured in areas of pervasive alteration and shows possible textural evidence of fault pulverization. The zones of localized and distributed strain have notably different spatial extents around the causative fault. The region of distributed deformation, as indicated by changes in gas permeability of the macroscopically intact rock, extends up to four times farther from the fault than the highest densities of localized deformation (i.e., fractures and deformation bands). This study identifies a set of fault-related processes that are pertinent to understanding the evolution of fault systems in poorly indurated tuff. Not surprisingly, the type of

  8. Long-term surveillance plan for the Burro Canyon disposal cell, Slick Rock, Colorado

    International Nuclear Information System (INIS)

    1996-11-01

    This long-term surveillance plant (LTSP) describes the US Department of energy's (DOE) long-term care program for the Uranium Mill Tailings Remediation Action (UMTRA) Project's burro Canyon disposal cell in San Miguel County, Colorado. This LTSP describes the long-term surveillance program the DOE will implement to ensure that the Burro Canyon disposal cell performs as designed. The program is based on site inspections to identify threats to disposal cell integrity. No ground water monitoring will be required at the Burro Canyon disposal cell because the ground water protection strategy is supplemental standards based on low-yield from the upper-most aquifer

  9. Impact of roof height non-uniformity on pollutant transport between a street canyon and intersections

    International Nuclear Information System (INIS)

    Nosek, Štěpán; Kukačka, Libor; Jurčáková, Klára; Kellnerová, Radka; Jaňour, Zbyněk

    2017-01-01

    This paper presents an extension of our previous wind-tunnel study (Nosek et al., 2016) in which we highlighted the need for investigation of the removal mechanisms of traffic pollution from all openings of a 3D street canyon. The extension represents the pollution flux (turbulent and advective) measurements at the lateral openings of three different 3D street canyons for the winds perpendicular and oblique to the along-canyon axis. The pollution was simulated by emitting a passive gas (ethane) from a homogeneous ground-level line source positioned along the centreline of the investigated street canyons. The street canyons were formed by courtyard-type buildings of two different regular urban-array models. The first model has a uniform building roof height, while the second model has a non-uniform roof height along each building's wall. The mean flow and concentration fields at the canyons' lateral openings confirm the findings of other studies that the buildings' roof-height variability at the intersections plays an important role in the dispersion of the traffic pollutants within the canyons. For the perpendicular wind, the non-uniform roof-height canyon appreciably removes or entrains the pollutant through its lateral openings, contrary to the uniform canyon, where the pollutant was removed primarily through the top. The analysis of the turbulent mass transport revealed that the coherent flow structures of the lateral momentum transport correlate with the ventilation processes at the lateral openings of all studied canyons. These flow structures coincide at the same areas and hence simultaneously transport the pollutant in opposite directions. - Highlights: • The pollutant transport strongly depends on the roof-height arrangement. • The non-uniform canyons also remove the pollutants through their lateral openings. • The higher the upstream wall, the more pollutant is removed through the top. • The lateral coherent structures correlate

  10. Fish Passage Assessment: Big Canyon Creek Watershed, Technical Report 2004.

    Energy Technology Data Exchange (ETDEWEB)

    Christian, Richard

    2004-02-01

    This report presents the results of the fish passage assessment as outlined as part of the Protect and Restore the Big Canyon Creek Watershed project as detailed in the CY2003 Statement of Work (SOW). As part of the Northwest Power Planning Council's Columbia Basin Fish and Wildlife Program (FWP), this project is one of Bonneville Power Administration's (BPA) many efforts at off-site mitigation for damage to salmon and steelhead runs, their migration, and wildlife habitat caused by the construction and operation of federal hydroelectric dams on the Columbia River and its tributaries. The proposed restoration activities within the Big Canyon Creek watershed follow the watershed restoration approach mandated by the Fisheries and Watershed Program. Nez Perce Tribal Fisheries/Watershed Program vision focuses on protecting, restoring, and enhancing watersheds and treaty resources within the ceded territory of the Nez Perce Tribe under the Treaty of 1855 with the United States Federal Government. The program uses a holistic approach, which encompasses entire watersheds, ridge top to ridge top, emphasizing all cultural aspects. We strive toward maximizing historic ecosystem productive health, for the restoration of anadromous and resident fish populations. The Nez Perce Tribal Fisheries/Watershed Program (NPTFWP) sponsors the Protect and Restore the Big Canyon Creek Watershed project. The NPTFWP has the authority to allocate funds under the provisions set forth in their contract with BPA. In the state of Idaho vast numbers of relatively small obstructions, such as road culverts, block thousands of miles of habitat suitable for a variety of fish species. To date, most agencies and land managers have not had sufficient, quantifiable data to adequately address these barrier sites. The ultimate objective of this comprehensive inventory and assessment was to identify all barrier crossings within the watershed. The barriers were then prioritized according to the

  11. Construction of the North Head (Maungauika) tuff cone: a product of Surtseyan volcanism, rare in the Auckland Volcanic Field, New Zealand

    Science.gov (United States)

    Agustín-Flores, Javier; Németh, Károly; Cronin, Shane J.; Lindsay, Jan M.; Kereszturi, Gábor

    2015-02-01

    The Auckland Volcanic Field (AVF) comprises at least 52 monogenetic eruption centres dispersed over ˜360 km2. Eruptions have occurred sporadically since 250 ka, predominantly when glacio-eustatic sea levels were lower than today. Now that around 35 % of the field is covered by shallow water (up to 30 m depth), any eruption occurring in the present or near future within this area may display Surtseyan dynamics. The North Head tuff cone evidences eruptive dynamics caused by magma interaction with seawater. The first stages of the eruption comprise a phreatomagmatic phase that built a 48-m-high tuff cone. North Head tuff deposits contain few lithic fragments (Auckland area was at least 10-12 m above the pre-eruptive surface. The hazards associated with this type of eruption pose a risk to the densely populated coastal residential zones and the activities of one of the busiest harbours in New Zealand.

  12. Diablo Canyon: the challenges of the Californian nuclear

    International Nuclear Information System (INIS)

    Avrin, Anne-Perrine; Zweibaum, Nicolas

    2014-01-01

    This article addresses the Californian nuclear plant of Diablo Canyon which, due to the shutting down of the two reactors of another plant, could be the last nuclear plant to operate in California as this state voted an interdiction of construction of any new nuclear plant until a permanent solution has been found for radioactive waste storage. It is outlined that this nuclear plant is the most controlled nuclear plant throughout the USA, presents an unchallenged security level despite it is built at the vicinity of seismic fault lines. It outlines that the problem of waste storage is far from being solved in California, and discusses the future role of nuclear energy in California within the context of global warming

  13. Public response to the Diablo Canyon Nuclear Generating Station

    International Nuclear Information System (INIS)

    Pijawka, K.D.

    1982-01-01

    The authors examine the nature of the public response to the Diablo Canyon Nuclear Generating Station located in San Luis Obispo, California, from the early 1960s to the present. Four distinct phases of public intervention were discerned, based on change in both plant-related issues and in the nature of the antinuclear constituencies in the region. The level of public concern varied both geographically and temporally and is related to the area's social structure, environmental predispositions, and distribution of plant-related economic benefits. External events, such as the prolonged debate over the risk assessment of the seismic hazard and the Three Mile Island accident were found to be important factors in explaining variation in public concern and political response

  14. Public response to the Diablo Canyon Nuclear Generating Station

    International Nuclear Information System (INIS)

    Pijawka, K.D.

    1982-01-01

    We examine the nature of the public response to the Diablo Canyon Nuclear Generating Station located in San Luis Obispo, California, from the early 1960s to the present. Four distinct phases of public intervention were discerned, based on change in both plant-related issues and in the nature of the antinuclear constituencies in the region. The level of public concern varied both geographically and temporally and is related to the area's social structure, environmental predispositions, and distribution of plant-related economic benefits. External events, such as the prolonged debate over the risk assessment of the seismic hazard and the Three Mile Island accident were found to be important factors in explaining variation in public concern and political response. (author)

  15. Microbial ecology of deep-water mid-Atlantic canyons

    Science.gov (United States)

    Kellogg, Christina A.

    2011-01-01

    The research described in this fact sheet will be conducted from 2012 to 2014 as part of the U.S. Geological Survey's DISCOVRE (DIversity, Systematics, and COnnectivity of Vulnerable Reef Ecosystems) Program. This integrated, multidisciplinary effort will be investigating a variety of topics related to unique and fragile deep-sea ecosystems from the microscopic level to the ecosystem level. One goal is to improve understanding, at the microbiological scale, of the benthic communities (including corals) that reside in and around mid-Atlantic canyon habitats and their associated environments. Specific objectives include identifying and characterizing the microbial associates of deep-sea corals, characterizing the microbial biofilms on hard substrates to better determine their role in engineering the ecosystem, and adding a microbial dimension to benthic community structure and function assessments by characterizing micro-eukaryotes, bacteria, and archaea in deep-sea sediments.

  16. Public response to the Diablo Canyon Nuclear Generating Station

    Energy Technology Data Exchange (ETDEWEB)

    Pijawka, K D [Arizona State Univ., Tempe (USA)

    1982-08-01

    We examine the nature of the public response to the Diablo Canyon Nuclear Generating Station located in San Luis Obispo, California, from the early 1960s to the present. Four distinct phases of public intervention were discerned, based on change in both plant-related issues and in the nature of the antinuclear constituencies in the region. The level of public concern varied both geographically and temporally and is related to the area's social structure, environmental predispositions, and distribution of plant-related economic benefits. External events, such as the prolonged debate over the risk assessment of the seismic hazard and the Three Mile Island accident were found to be important factors in explaining variation in public concern and political response.

  17. Evaluation of air quality and noise impact assessments, Davis Canyon

    International Nuclear Information System (INIS)

    1986-05-01

    In this report, several issues are identified regarding the air quality and noise assessments presented in the final salt repository environmental assessment (EA) prepared by the US Department of Energy for the Davis Canyon, Utah, site. Necessary revisions to the data and methods used to develop the EA impact assessment are described. Then, a comparative evaluation is presented in which estimated impacts based upon the revised data and methods are compared with the impacts published in the EA. The evaluation indicates that the conclusions of the EA air quality and noise impact sections would be unchanged. Consequently, the guideline findings presented in Chapter 6 of the EA are also unchanged by the revised analysis. 50 refs., 16 tabs

  18. Achieving quality excellence at the Diablo Canyon Nuclear Power Plant

    International Nuclear Information System (INIS)

    Skidmore, S.M.; Taggart, D.A.

    1988-01-01

    Quality assurance methods at the Diablo Canyon plant were transformed from the then typical industry practices that often alienated professional and technical people, as well as craftsmen and their foremen, to a cooperative method that allowed plant personnel to work together as a team. It has created an attitude to do it right the first time. The roles of quality professionals were expanded to include teaching and coaching to facilitate enhanced communication between and within functional organizations. This included regular presentations to managers and line personnel in an informal group participative atmosphere. These presentations have become widely known at the plant as quality awareness tailboard sessions. These presentations are intended to increase personnel sensitivity to the subject of quality and quality management. Economic achievement of excellence in quality is essential to remain competitive in today's marketplace. The proactive team-oriented approach of quality assurance achieves the bottom line of high quality with concurrently enhanced productivity and cost-effectiveness

  19. Extended power-law scaling of air permeabilities measured on a block of tuff

    Directory of Open Access Journals (Sweden)

    M. Siena

    2012-01-01

    Full Text Available We use three methods to identify power-law scaling of multi-scale log air permeability data collected by Tidwell and Wilson on the faces of a laboratory-scale block of Topopah Spring tuff: method of moments (M, Extended Self-Similarity (ESS and a generalized version thereof (G-ESS. All three methods focus on q-th-order sample structure functions of absolute increments. Most such functions exhibit power-law scaling at best over a limited midrange of experimental separation scales, or lags, which are sometimes difficult to identify unambiguously by means of M. ESS and G-ESS extend this range in a way that renders power-law scaling easier to characterize. Our analysis confirms the superiority of ESS and G-ESS over M in identifying the scaling exponents, ξ(q, of corresponding structure functions of orders q, suggesting further that ESS is more reliable than G-ESS. The exponents vary in a nonlinear fashion with q as is typical of real or apparent multifractals. Our estimates of the Hurst scaling coefficient increase with support scale, implying a reduction in roughness (anti-persistence of the log permeability field with measurement volume. The finding by Tidwell and Wilson that log permeabilities associated with all tip sizes can be characterized by stationary variogram models, coupled with our findings that log permeability increments associated with the smallest tip size are approximately Gaussian and those associated with all tip sizes scale show nonlinear variations in ξ(q with q, are consistent with a view of these data as a sample from a truncated version (tfBm of self-affine fractional Brownian motion (fBm. Since in theory the scaling exponents, ξ(q, of tfBm vary linearly with q we conclude that nonlinear scaling in our case is not an indication of multifractality but an artifact of sampling from tfBm. This allows us to explain theoretically how power-law scaling of our data, as well

  20. OBSERVATION AND ANALYSIS OF A PRONOUNCED PERMEABILITY AND POROSITY SCALE-EFFECT IN UNSATURATED FRACTURED TUFF

    Energy Technology Data Exchange (ETDEWEB)

    V. VESSELINOV; ET AL

    2001-01-01

    Over 270 single-hole (Guzman et al., 1996) and 44 cross-hole pneumatic injection tests (Illman et al., 1998; Illman, 1999) have been conducted at the Apache Leap Research Site (ALRS) near Superior, Arizona. They have shown that the pneumatic pressure behavior of fractured tuff at the site is amenable to analysis by methods which treat the rock as a continuum on scales ranging from meters to tens of meters, and that this continuum is representative primarily of interconnected fractures. Both the single-hole and cross-hole test results are free of skin effect. Single-hole tests have yielded estimates of air permeability at various locations throughout the tested rock volume, on a nominal support scale of about 1 m. The corresponding log permeability data exhibit spatial behavior characteristic of a random fractal and yield a kriged estimate of how these 1-m scale log permeabilities vary in three-dimensional space (Chen et al., 2000). Cross-hole tests have been analyzed by means of a three-dimensional inverse model (Vesselinov et al., 2000) in two ways: (a) by interpreting pressure records from individual borehole monitoring intervals, one at a time, while treating the rock as if it was spatially uniform; and (b) by using the inverse model to interpret pressure records from multiple tests and borehole monitoring intervals simultaneously, while treating the rock as a random fractal characterized by a power variogram. The first approach has yielded equivalent air permeabilities and air-filled porosities for a rock volume characterized by a length-scale of several tens of meters. Comparable results have been obtained by means of type-curves (Illman and Neuman, 2001). The second approach amounts to three-dimensional pneumatic tomography, or stochastic imaging, of the rock. It has yielded a high-resolution geostatistical estimate of how air permeability and air-filled porosity, defined over grid blocks having a length-scale of 1 m, vary throughout the modeled rock volume

  1. The role of tephra studies in African paleoanthropology as exemplified by the Sidi Hakoma Tuff

    Science.gov (United States)

    WoldeGabriel, Giday; Endale, Tamrat; White, Tim D.; Thouveny, Nicolas; Hart, William K.; Renne, Paul R.; Asfaw, Berhane

    2013-01-01

    Beginning in the 1960s, geological and paleoanthropological exploration of the Ethiopian rift system's basins have led to the discovery and assembly of the most comprehensive record of human biological and technological change during the last 6 million years. The hominid fossils, including partial skeletons, were primarily discovered in the Afar Rift, the Main Ethiopian Rift, and in the Omo Basin of the broadly rifted zone of SW Ethiopia. The paleoanthropological research areas within the SW Afar Rift that have yielded many diverse hominid species and the oldest stone tools are, from north to south, Woranso-Mille (aff. Ardipithecus and Au. afarensis), Hadar (Au. afarensis, Homo sp.), Dikika (Au. afarensis), Gona (Ar. kadabba, Ar. ramidus, H. erectus, and oldest stone tools), Middle Awash (Ar. kadabba, Ar. ramidus, Au. anamensis, Au. afarensis, Au. garhi, H. erectus, H. rhodesiensis, H. sapiens idaltu, and the oldest paleo-butchery locality), and Galili (Au. afarensis). Additional hominid remains were discovered at Melka Kunture on the banks of the Awash River near its source along the western margin of the central part of the Main Ethiopian Rift (H. erectus), at Konso (H. erectus and A. boisei), and at the southern end of the MER, and in the Omo Basin (Au. anamensis, Au. afarensis, Au. aethiopicus, Au. boisei, H. habilis, and H. erectus). Distal and sometimes proximal tephra units interbedded within fossilifeous sedimentary deposits have become key elements in this work by providing chronological and correlative control and depositional contexts. Several regional tephra markers have been identified within the northern half of the eastern African rift valley in Ethiopia and Kenya, and in marine sediments of the Gulf of Aden Rift and the NW Indian Ocean. Out of the many regional tephra stratigraphic markers that range in age from the early Pliocene (3.97 Ma) to the late Pleistocene (0.16 Ma), the Sidi Hakoma Tuff (SHT) has been more widely identified and thoroughly

  2. Paleomagnetism and Anisotropy of Magnetic Susceptibility study of the Miocene Jack Springs Tuff (Nevada, USA)

    Science.gov (United States)

    Shields, S.; Petronis, M. S.; Pluhar, C. J.; Gordon, L.

    2014-12-01

    The mid-Miocene Jack Springs Tuff (JST) outcrops across the western Mina Deflection accommodation zone, west-central Nevada and into eastern California. Previously, the source location for the JST was unknown, yet recent studies northwest of Mono Lake, CA have identified a relatively un-rotated structural block in which to reference the paleomagnetic data. Although new studies have indicated that this block may be rotated up to 13º, we argue that the probable source area is located near the Bodie Hills, CA. At this site, the paleomagnetic reference direction is D = 353°, I = 43°, α95 = 7.7° (Carlson et al, 2013). Based on these data, the JST can be used to measure absolute vertical-axis rotation as well as enable reconstruction of the paleo-topography using the corrected anisotropy of magnetic susceptibility (AMS) data. A total of 19 sites were sampled to constrain Cenozoic to recent vertical axis rotation within the region and AMS experiments were conducted to determine the flow direction of the JST. Curie point estimates indicate that the JST ranges in titanium concentration from 0.042 to 1.10, indicating a low to moderate titanomagnetite phase (Akimoto, 1962). Demagnetization experiments reveal mean destructive fields of the NRM ranging between 15mT and 40mT suggesting that both multi-domain to pseudo-single domain grains are the dominant ferromagnetic phases that carry the remanence and AMS fabric. Preliminary paleomagnetic data yield stable single component demagnetization behavior for most sites that, after structural correction, indicate clockwise vertical axis rotation ranging from +20°± 10° to +60°± 11° between multiple fault blocks. The uncorrected AMS data yield oblate magnetic fabrics that can be used to infer the transport direction, source region, and paleovalley geometry of the JST. These data are tentatively interpreted to indicate west to east transport of the JST across the Mono Basin region into the Mina Deflection that was erupted and

  3. Influence of Lithophysal Geometry on the Uniaxial Compression of Tuff-Like Rock

    International Nuclear Information System (INIS)

    Rigby, Douglas B.

    2007-01-01

    A large portion of the rock of the high-level nuclear waste repository at Yucca Mountain contains lithophysae or voids. These voids have a significant detrimental effect on the engineering properties of the rock mass and its performance. The lithophysae were formed at the time of volcanic deposition by pockets of gas trapped within the compressing and cooling pyroclastic flow material. Lithophysae vary by size, shape, and spatial frequency of occurrence. Due to the difficulties of testing actual lithophysal rock, the current mechanical property data set is limited and the numerical models of lithophysal rock are not well validated. The purpose of this task was to experimentally quantify the effect of void geometry in the mechanical compression of cubes of analog lithophysal-like rock. In this research the mechanical properties of the analog rock were systematically studied by examining various patterns of voids based on variables consisting of hole shape, size, and geometrical distribution. Each specified hole pattern was cast into 6 by 6 by 6-in. Hydro-StoneTB(reg s ign) specimens (produced in triplicate) and then tested under uniaxial compression. Solid Hydro-StoneTB(reg s ign) specimens exhibited similar mechanical properties to those estimated for rock mass solid specimens of Topopah Spring tuff. The results indicated that the compressive strength and Young's Modulus values decrease with increasing specimen void porosity. The modulus and strength with void porosity relationships are essentially linear over the 5 to 20 percent void porosity range. When zero void porosity (solid specimen) results are added, exponential functions do not provide a good fit to the data due to a significant sensitivity of strength and modulus to the presence of macro-sized voids. From solid specimens there is roughly a 60 percent drop in strength with about 7 percent void porosity, increasing to an 80 percent drop at about 20 percent void porosity. The percent change in modulus from

  4. On magma fragmentation by conduit shear stress: Evidence from the Kos Plateau Tuff, Aegean Volcanic Arc

    Science.gov (United States)

    Palladino, Danilo M.; Simei, Silvia; Kyriakopoulos, Konstantinos

    2008-12-01

    Large silicic explosive eruptions are the most catastrophic volcanic events. Yet, the intratelluric mechanisms underlying are not fully understood. Here we report a field and laboratory study of the Kos Plateau Tuff (KPT, 161 ka, Aegean Volcanic Arc), which provides an excellent geological example of conduit processes that control magma vesiculation and fragmentation during intermediate- to large-scale caldera-forming eruptions. A prominent feature of the KPT is the occurrence of quite unusual platy-shaped tube pumice clasts in pyroclastic fall and current deposits from the early eruption phases preceding caldera collapse. On macroscopic and SEM observations, flat clast faces are elongated parallel to tube vesicles, while transverse surfaces often occur at ~ 45° to vesicle elongation. This peculiar pumice texture provides evidence of high shear stresses related to strong velocity gradients normal to conduit walls, which induced vesiculation and fragmentation of the ascending magma. Either an increasing mass discharge rate without adequate enlargement of a narrow central feeder conduit or a developing fissure-like feeder system related to incipient caldera collapse provided suitable conditions for the generation of plate tube pumice within magma volumes under high shear during the pre-climactic KPT eruption phases. This mechanism implies that the closer to the conduit walls (where the stronger are the velocity gradients) the larger was the proportion of plate vs. conventional (lensoid) juvenile fragments in the ascending gas-pyroclast mixture. Consequently, plate pumice clasts were mainly entrained in the outer portions of the jet and convecting regions of a sustained, Plinian-type, eruption column, as well as in occasional lateral blast currents generated at the vent. As a whole, plate pumice clasts in the peripheral portions of the column were transported at lower altitudes and deposited by fallout or partial collapse closer to the vent relative to lensoid ones

  5. Busted Butte report on laboratory radionuclide migration experiments in non-welded tuff under unsaturated conditions

    Energy Technology Data Exchange (ETDEWEB)

    Vandergraaf, T.T.; Drew, D.J.; Ticknor, K.V

    2002-11-01

    Three blocks of non-welded tuff, one nominally one cubic foot (trial block) and the other two, nominally one cubic metre (1 m{sup 3}), were excavated from the Busted Butte Test Facility on the Nevada Test Site and transported to the Atomic Energy of Canada Limited Whiteshell Laboratories in Pinawa, Manitoba. The trial block and one of the 1-m{sup 3} blocks were used for unsaturated flow experiments. The remaining 1-m{sup 3} block is being used for saturated flow experiments and will be reported on separately. After a vertical flow of synthetic transport solution was set up under unsaturated conditions, a suite of conservative and chemically reactive radionuclide tracers was injected at volumetric flow rates of 20 mL/hr in the trial block, and 10 mL/hr in the 1-m{sup 3} block. The duration of the migration experiment in the trial block was 87 days, while the migration experiment in the 1-m{sup 3} block was continuing after 600 days. Results obtained from the migration experiment in the trial block showed that transport of {sup 95m+99}Tc, injected as the pertechnetate (an)ion, was slightly faster than that of the transport solution, using tritiated water ({sup 3}H{sub 2}O) as a flow indicator. Retardation of {sup 237}Np was consistent with that predicted from results obtained in supporting static batch sorption studies. Post-migration analysis of the flow field in the trial block showed that the front of the {sup 22}Na had migrated about half the distance through the block, and that {sup 60}Co and {sup 137}Cs had been retained near the inlet. This observation agrees qualitatively with that predicted from the results from static batch sorption studies. In the larger scale experiment, the transport behavior of Tc is very similar to that of the transport solution at this point in time. None of the other radionuclide tracers have been detected in water collected from this block. This observation is consistent with the observations for the smaller block. (author)

  6. Hydrovolcanic and Hydrothermal Biomediated Mineral Growth in Basaltic Tuff, Surtsey Volcano, Iceland

    Science.gov (United States)

    Jackson, M. D.; Couper, S.; Ivarsson, M.; Stan, C. V.; Tamura, N.; Miyagi, L. M.; Moore, J. G.

    2017-12-01

    Fine-scale analyses of hydroclasts in 1979 Surtsey basaltic tuff drill core provide new methods for examining hydrovolcanic and hydrothermal magma-rock influences on biomediated alteration in palagonitized submarine tephra. Synchrotron source X-ray microdiffraction and microfluorescence studies from Advanced Light Source beamline 12.3.2, epifluorescent UVA illumination microscopy, S/TEM EDX compositional analyses, and Raman spectroscopy define diverse nanocrystalline clay mineral structures at 137.9 m depth (93.8 °C (1980)) and 102.6 m depth (141.3 °C (1980)). At 137.9 m, olivine contains endolithic microborings; vermicular microstructures in altered glass contain nontronite exhibiting crystallographic preferred orientation; and 75-150 µm sub-circular microstructures in altered glass contain Al-tobermorite, a calcium-silicate-hydrate with 11.3 Å interlayer spacing, zeolite, and epifluorescent, thread-like structures. At 102.6 m depth, concentrically-layered microstructures occur in altered glass and altered olivine. These have nontronite crystallographic preferred orientations that rotate around a longitudinal axis commonly occupied by a 10-80 µm long, epifluorescent thread-like structure. Pronounced carbon concentrations detected by S/TEM EDX trace layer boundaries. First-order Raman bands at 1370 cm-1 (disorder-related) and at 1580 cm-1 (order-related), and second-order bands at 2500-3300 cm-1 (overtone scattering) detect degraded organic carbonaceous matter, a strong indication of biological origin. Sub-circular nanostructures in altered glass at 137.9 m depth show similar spectra. Borehole fluid temperatures at 102.6 m, 141.3 °C in 1980, exceeded 130 °C, the assumed limit for growth of microorganisms, however. Previous analyses suggest an early low temperature episode in submarine deposits, prior to development of a hydrothermal system driven by 1964-1967 magmatic intrusions. The abundant traces of biomediated nanocrystalline clay mineral growth validate

  7. RECALIBRATION OF H CANYON ONLINE SPECTROPHOTOMETER AT EXTENDED URANIUM CONCENTRATION

    International Nuclear Information System (INIS)

    Lascola, R

    2008-01-01

    The H Canyon online spectrophotometers are calibrated for measurement of the uranium and nitric acid concentrations of several tanks in the 2nd Uranium Cycle.[1] The spectrometers, flow cells, and prediction models are currently optimized for a process in which uranium concentrations are expected to range from 0-15 g/L and nitric acid concentrations from 0.05-6 M. However, an upcoming processing campaign will involve 'Super Kukla' material, which has a lower than usual enrichment of fissionable uranium. Total uranium concentrations will be higher, spanning approximately 0-30 g/L U, with no change in the nitric acid concentrations. The new processing conditions require the installation of new flow cells with shorter path lengths. As the process solutions have a higher uranium concentration, the shorter path length is required to decrease the absorptivity to values closer to the optimal range for the instrument. Also, new uranium and nitric acid prediction models are required to span the extended uranium concentration range. The models will be developed for the 17.5 and 15.4 tanks, for which nitric acid concentrations will not exceed 1 M. The restricted acid range compared to the original models is anticipated to reduce the measurement uncertainty for both uranium and nitric acid. The online spectrophotometers in H Canyon Second Uranium Cycle were modified to allow measurement of uranium and nitric acid for the Super Kukla processing campaign. The expected uranium concentrations, which are higher than those that have been recently processed, required new flow cells with one-third the optical path length of the existing cells. Also, new uranium and nitric acid calibrations were made. The estimated reading uncertainties (2σ) for Tanks 15.4 and 17.5 are ∼5% for uranium and ∼25% for nitric acid

  8. Gas phase migration of C-14 through barrier materials applicable for use in a high-level nuclear waste repository located in tuff

    International Nuclear Information System (INIS)

    Bauer, L.R.

    1988-12-01

    A study of the movement of 14 CO 2 through proposed barrier media has been conducted. Diffusion coefficients for crushed tuff, bentonite and a 90:10% by wt. mixture of crushed tuff and bentonite were measured for two diffusion lengths. The ability of 14 CO 2 to penetrate a microsilica-containing portland cement mortar proposed for repository use was also examined. The specimens were subjected to uniaxially-applied compressive loads prior to the diffusion tests to simulate the onset of environmentally-induced microcracks. 91 refs., 14 figs., 15 tabs

  9. Formation of Box Canyon, Idaho, by megaflood: implications for seepage erosion on Earth and Mars.

    Science.gov (United States)

    Lamb, Michael P; Dietrich, William E; Aciego, Sarah M; Depaolo, Donald J; Manga, Michael

    2008-05-23

    Amphitheater-headed canyons have been used as diagnostic indicators of erosion by groundwater seepage, which has important implications for landscape evolution on Earth and astrobiology on Mars. Of perhaps any canyon studied, Box Canyon, Idaho, most strongly meets the proposed morphologic criteria for groundwater sapping because it is incised into a basaltic plain with no drainage network upstream, and approximately 10 cubic meters per second of seepage emanates from its vertical headwall. However, sediment transport constraints, 4He and 14C dates, plunge pools, and scoured rock indicate that a megaflood (greater than 220 cubic meters per second) carved the canyon about 45,000 years ago. These results add to a growing recognition of Quaternary catastrophic flooding in the American northwest, and may imply that similar features on Mars also formed by floods rather than seepage erosion.

  10. Data Quality Objectives Summary Report for the 221-U Canyon Disposition Alternatives

    International Nuclear Information System (INIS)

    Miller, M.S.; Oaces, L.E.; Baxter, J.; Brown, T.M.; Enoke, D.E.; Carlson, D.; Rugg, J.E.

    1997-08-01

    The 221-U Canyon Disposition Alternatives Data Quality Objective (DQO) Process identifies the sampling and analytical requirements necessary to support future detailed evaluation of alternatives via the CERCLA process, for final disposition of the 221-U Canyon Facility. Viable alternatives for the disposition of the 221-U Facility have been identified in a CERCLA Phase I Feasibility Study (FS) (DOE-RL 1997) for the Canyon Disposition Initiative (CDI). The scope of this DQO Process is limited to the 221-U Process Canyon Building and equipment contained within the facility. Associated stacks, filters, solvent handling, vaults, and storage facilities external to the 221-U Building are not addressed in this DQO. This DQO focuses on the 221-U Building because it provides the greatest potential source of contaminant volumes and concentrations and the physical structure poses the greatest challenge for disposition decisions

  11. 76 FR 23623 - Backcountry Management Plan, Environmental Impact Statement, Grand Canyon National Park, Arizona

    Science.gov (United States)

    2011-04-27

    ...-7945, [email protected] or Rachel Bennett, Environmental Protection Specialist, P.O. Box 129, Grand Canyon, Arizona 86023, 928-638-7326, Rachel[email protected] . SUPPLEMENTARY INFORMATION: If you wish to...

  12. Deepwater Canyons 2012: Pathways to the Abyss on NOAA Ship Nancy Foster between 20120815 and 20121001

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Mid-Atlantic Deep-Water Canyons project is co-funded by the Bureau of Ocean Energy Management (BOEM) and NOAA's Office of Ocean Exploration and Research (which...

  13. Integrated Project Management Planning for the Deactivation of the Savannah River Site F-Canyon Complex

    Energy Technology Data Exchange (ETDEWEB)

    Clark, T.G.

    2000-12-01

    This paper explains the planning process that is being utilized by the Westinghouse Savannah River Company to take the F-Canyon Complex facilities from operations to a deactivated condition awaiting final decommissioning.

  14. Fire modeling for Building 221-T - T Plant Canyon Deck and Railroad Tunnel

    International Nuclear Information System (INIS)

    Oar, D.L.

    1994-01-01

    This report was prepared by Hughes Associates, Inc. to document the results of fire models for building 221-T Canyon Deck and Railroad Tunnel. Backup data is contained in document No. WHC-SD-CP-ANAL-010, Rev. 0

  15. Lightning protection for the process canyons at the Savannah River site

    International Nuclear Information System (INIS)

    McAfee, D.E.

    1995-01-01

    Westinghouse Savannah River Company (WSRC) has performed Lightning Studies for the existing Process Canyons at the Savannah River Site (SRS). These studies were initiated to verify the lightning protection systems for the facilities and to compare the installations to the National Fire Protection (NFPA) Standard 780, Lighting Protection Code, 1992. The original study of the F-Canyon was initiated to develop answers to concerns raised by the Defense Nuclear Facility Safety Board (DNFSB). Once this study was completed it was determined that a similar study for H-Canyon would be prudent; followed by an evaluation of the Defense Waste Processing Facility (DWPF) Vitrification Building (S-Canyon). This paper will provide an overview of the nature of lightning and the principals of lightning protection. This will provide the reader with a basic understanding of the phenomena of lighting and its potential for damaging structures, components, and injuring personnel in or near the structure

  16. Submarine canyons along the upper Sardinian slope (Central Western Mediterranean) as repositories for derelict fishing gears.

    Science.gov (United States)

    Cau, Alessandro; Alvito, Andrea; Moccia, Davide; Canese, Simonepietro; Pusceddu, Antonio; Rita, Cannas; Angiolillo, Michela; Follesa, Maria C

    2017-10-15

    By means of ROV surveys, we assessed the quantity, composition and bathymetric distribution of marine litter in 17 sites along the Sardinian continental margin (Central Western Mediterranean) at depths ranging from 100 to 480m. None of the investigated sites was litter free, but the mean density of litter (0.0175±0.0022itemsm -2 ) was lower than that reported from other Tyrrhenian regions. The difference in the total litter density among sites was negligible, but the density of derelict fishing gear (DFG) items (most of which ascribable to small scale fishery) in submarine canyons was higher in submarine canyons than in other habitats. Our result suggest that submarine canyons (known to be highly vulnerable ecosystems) act as major repositories of DFGs, and, therefore, we anticipate the need of specific measures aimed at minimizing the loss and abandonment of DFGs in submarine canyons. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Investigation of bacterial transport in the large-block test, a thermally perturbed block of Topopah Spring tuff

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.I.; Meike, A.; Chuu, Y.J.; Sawvel, A.; Lin, W.

    1999-07-01

    Transport of bacteria is investigated as part of the Large-Block Test (LBT), a thermally perturbed block of Topopah Spring tuff. Two bacterial species, Bacillus subtilis and Arthrobacter oxydans, were isolated from the Yucca Mountain Tuff. Natural mutants that can grow under the simultaneous presence of the two antibiotics, streptomycin and rifampicin, were selected from these species by laboratory procedures, cultured, and injected into the five heater boreholes of the large block hours before heating was initiated. The temperature, as measured 5 cm above one of the heater boreholes, rose slowly over a matter of months to a maximum of 142 C and to 60 C at the top and bottom of the block. Samples were collected from boreholes located approximately 5 ft below the injection points. Double-drug-resistant microbes also appeared in the heater boreholes where the temperature had been sustainably high throughout the test. The number of double-drug-resistant bacteria that were identified in the collection boreholes increased with time until the heater was deactivated. Negative indications in the collection holes after the heater was deactivated support the supposition that these bacteria were the species that were injected. An apparent homogeneous distribution among the collection boreholes suggests no pattern to the migration of bacteria through the block. The relationship between bacterial migration and the movement of water is not yet understood. These observations indicate the possibility of rapid bacterial transport in a thermally perturbed geologic setting. The implications for colloid transport need to be reviewed.

  18. Investigation of bacterial transport in the large-block test, a thermally perturbed block of Topopah Spring tuff

    International Nuclear Information System (INIS)

    Chen, C.I.; Meike, A.; Chuu, Y.J.; Sawvel, A.; Lin, W.

    1999-01-01

    Transport of bacteria is investigated as part of the Large-Block Test (LBT), a thermally perturbed block of Topopah Spring tuff. Two bacterial species, Bacillus subtilis and Arthrobacter oxydans, were isolated from the Yucca Mountain Tuff. Natural mutants that can grow under the simultaneous presence of the two antibiotics, streptomycin and rifampicin, were selected from these species by laboratory procedures, cultured, and injected into the five heater boreholes of the large block hours before heating was initiated. The temperature, as measured 5 cm above one of the heater boreholes, rose slowly over a matter of months to a maximum of 142 C and to 60 C at the top and bottom of the block. Samples were collected from boreholes located approximately 5 ft below the injection points. Double-drug-resistant microbes also appeared in the heater boreholes where the temperature had been sustainably high throughout the test. The number of double-drug-resistant bacteria that were identified in the collection boreholes increased with time until the heater was deactivated. Negative indications in the collection holes after the heater was deactivated support the supposition that these bacteria were the species that were injected. An apparent homogeneous distribution among the collection boreholes suggests no pattern to the migration of bacteria through the block. The relationship between bacterial migration and the movement of water is not yet understood. These observations indicate the possibility of rapid bacterial transport in a thermally perturbed geologic setting. The implications for colloid transport need to be reviewed

  19. Petrochemical variation of Topopah Spring tuff matrix with depth (stratigraphic level), drill hole USW G-4, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Byers, F.M. Jr.

    1985-12-01

    This study describes and interprets petrochemical variation of the matrix (excluding fractures and large gas cavities) of the Topopah Spring Member of the Paintbrush Tuff. This tuff includes the candidate host rock for a high-level nuclear waste repository at Yucca Mountain on the Nevada Test Site. Cored hole USW G-4, near the site of a potential exploratory shaft at Yucca Mountain, penetrated 359.4 m (1179 ft) of the member within the unsaturated zone. This study shows that petrographic textures and chemistry of the matrix vary systematically within recognizable lithologic subunits related to crystallization (cooling) zones, welding (compaction) zones, and compositional zones (rhyolite versus quartz latite). The methods used for this study include petrographic modal thin section analysis using an automated counter and electron microprobe analysis of the groundmass. Distinctive textural categories are defined, and they can be ranked from finest to coarsest as vitrophyre (glass), cryptocrystalline groundmass, spherulites, granophyre, lithic fragments, and phenocrysts. The two main groundmass compositions are also defined: rhyolite high silica) and quartz latite. The value of these petrochemical studies lies in providing microscopic criteria for recognizing the zonal subunits where they may have greatly limited exposure, as in mined drifts and in core from horizontal drill holes. For example, the lower nonlithophysal zone can be distinguished microscopically from the middle nonlithophysal zone by (1) degree of compaction, (2) amount of quartz, and (3) amount of lithic fragments. The variability between these textural categories should also be considered in designing physical and chemical tests of the Topopah Spring

  20. Petrochemical variation of Topopah Spring tuff matrix with depth (stratigraphic level), drill hole USW G-4, Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Byers, F.M. Jr.

    1985-12-01

    This study describes and interprets petrochemical variation of the matrix (excluding fractures and large gas cavities) of the Topopah Spring Member of the Paintbrush Tuff. This tuff includes the candidate host rock for a high-level nuclear waste repository at Yucca Mountain on the Nevada Test Site. Cored hole USW G-4, near the site of a potential exploratory shaft at Yucca Mountain, penetrated 359.4 m (1179 ft) of the member within the unsaturated zone. This study shows that petrographic textures and chemistry of the matrix vary systematically within recognizable lithologic subunits related to crystallization (cooling) zones, welding (compaction) zones, and compositional zones (rhyolite versus quartz latite). The methods used for this study include petrographic modal thin section analysis using an automated counter and electron microprobe analysis of the groundmass. Distinctive textural categories are defined, and they can be ranked from finest to coarsest as vitrophyre (glass), cryptocrystalline groundmass, spherulites, granophyre, lithic fragments, and phenocrysts. The two main groundmass compositions are also defined: rhyolite high silica) and quartz latite. The value of these petrochemical studies lies in providing microscopic criteria for recognizing the zonal subunits where they may have greatly limited exposure, as in mined drifts and in core from horizontal drill holes. For example, the lower nonlithophysal zone can be distinguished microscopically from the middle nonlithophysal zone by (1) degree of compaction, (2) amount of quartz, and (3) amount of lithic fragments. The variability between these textural categories should also be considered in designing physical and chemical tests of the Topopah Spring.