1,999 Matching Results

Search Results

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

Description: 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.
Date: December 1982
Creator: Scott, R. B.; Spengler, R. W.; Diehl, S.; Lappin, A. R. & Chornack, M. P.
Partner: UNT Libraries Government Documents Department

Nuclear-waste isolation in the unsaturated zone of arid regions

Description: The vadose zone in arid regions is considered as a possible environment for geologic isolation of nuclear waste. There are several topographic and lithologic combinations in the vadose zone of arid regions that may lend themselves to waste isolation considerations. In some cases, topographic highs such as mesas and interbasin ranges - comprised of several rock types, may contain essentially dry or partially saturated conditions favorable for isolation. The adjacent basins, especially in the far western and southwestern US, may have no surface or subsurface hydrologic connections with systems ultimately leading to the ocean. Some rock types may have the favorable characteristics of very low permeability and contain appropriate minerals for the strong chemical retardation of radionuclides. Environments exhibiting these hydrologic and geochemical attributes are the areas underlain by tuffaceous rocks, relatively common in the Basin and Range geomorphic province. Adjacent valley areas, where tuffaceous debris makes up a significant component of valley fill alluvium, may also contain thick zones of unsaturated material, and as such also lend themselves to strong consideration as respository environments. This paper summarizes the aspects of nuclear waste isolation in unsaturated regimes in alluvial-filled valleys and tuffaceous rocks of the Basin and Range province.
Date: May 1, 1982
Creator: Wollenberg, H.A.; Wang, J.S.Y. & Korbin, G.
Partner: UNT Libraries Government Documents Department

Leach testing of waste forms: interrelationship of ISO- and MCC-type tests

Description: Leach testing experiments were conducted on SYNROC-D material to examine the parameters which affect leaching results and to measure the activation energy for leaching of elements from SYNROC-D. Measured leach rates were found to be controlled by precipitation of insoluble phases for those tests where the sample surface area to volume of leachant (SA/V) multiplied by leaching time (t) exceeded 0.3 cm{sup -1}d for leach tests at 90{sup 0}C. In these cases the apparent activation energy for leaching was approximately 10 kcal/mole based on Na and Si data. For leach tests at 90{sup 0}C with (SA/V)(t) less than 0.2 cm{sup -1}d, the activation energy for Na and Si dissolution was 18.5 kcal/mole for sample S29 and 14.5 kcal/mole for sample LS04. These activation energies are in agreement with values reported by Tole and Lasaga (1981) for nepheline dissolution. The effect of sample geometry was investigated by leaching a series of crushed samples of different grain size. The results support the view that geometric surface area should be used in leach rate calculations rather than gas adsorption BET surface area. Comparison of results on S29 leaching of crushed samples and monoliths show that data from MCC-1 and ISO type leach tests may be directly compared when the data are examined at constant (SA/V)(t).
Date: May 14, 1982
Creator: Oversby, V.M.
Partner: UNT Libraries Government Documents Department

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

Description: 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.
Date: December 1982
Creator: Erdal, B. R.; Bish, D. L.; Crowe, B. M.; Daniels, W. R.; Ogard, A. E.; Rundberg, R. S. et al.
Partner: UNT Libraries Government Documents Department

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

Description: 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{sup 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{sup 2}), in part due to compacted bentonite`s relatively low thermal conductivity when dehydrated ({similar_to}0.6 +- 0.2 W/m{sup 0}C). Because our groundwater contains K{sup +}, an upper hydrothermal temperature limit appears to be 120 to 150{sup 0}C. At much lower power densities (less than 1 kW per package and an areal density of 12 W/m{sup 2}), bentonite may be suitable.
Date: January 1, 1982
Creator: Rothman, A.J.
Partner: UNT Libraries Government Documents Department

Calculated and measured drift closure during the spent-fuel test in Climax granite

Description: Horizontal and vertical measurements of drift closures have been made with a manually operated tape extensometer since about 6 weeks after the emplacement of the spent fuel at various locations along the length of the drifts. The averaged closures are less than 0.6 mm from the onset of measurements through about two years after the spent fuel emplacement. These results have been compared with thermo-elastic finite element calculations using measured medium properties. The comparisons show that most of the closure of the drifts occurred between the time the spent fuel was emplaced and the time of first measurement. The comparisons show that the results track each other, in that where closure followed by dilation is measured, the calculations also show this effect. The agreement is excellent, although where closures of less than 0.2 mm are measured the comparison with calculations is limited by measurement reproducability. Once measurements commenced the averaged measured closures remain to within 30% of the calculated total closure in each drift. 9 figures, 1 table.
Date: April 1, 1982
Creator: Yow, J.L. Jr. & Butkovich, T.R.
Partner: UNT Libraries Government Documents Department

Experimental and calculational results from the Spent Fuel Test-Climax

Description: The Spent Fuel Test-Climax (SFT-C) is being conducted under the technical direction of the Lawrence Livermore National Laboratory for the US Department of Energy. The SFT-C is located 420 m below surface in the Climax placed in test storage in April and May 1980. At the same time, 6 electrical elevated-temperature phase of the test. Data related to heat transfer, thermomechanical response, radiation dose, and radiation damage have been collected and are presented here, as appropriate, with calculational results. In general, measured and calculated results compare well.
Date: October 14, 1982
Creator: Patrick, W.C.; Ramspott, L.D. & Ballou, L.B.
Partner: UNT Libraries Government Documents Department

Status report on the Spent-Fuel Test-Climax, Nevada Test Site: a test of dry storage of spent fuel in a deep granite location

Description: The Spent Fuel Test-Climax (SFT-C) is located at a depth of 420 m in the Climax granite at the Nevada Test Site. The test array contains 11 canistered PWR fuel assemblies, plus associated electrical simulators and electrical heaters. There are nearly 900 channels of thermal, radiation, stress, displacement, and test control instrumentation. This paper is a general status report on the test, which started in May 1980.
Date: March 1, 1982
Creator: Ramspott, L. D.; Ballou, L. B. & Patrick, W. C.
Partner: UNT Libraries Government Documents Department

Tritium Deposition in Pine Trees and Soil from Atmospheric Releases of Molecular Tritium

Description: Much of the tritium found in soil and leaf litter near a chemical separations facility is incorporated into soil organic matter in a stable non-exchangeable form. Formation of this ''bound'' tritium seems to result from the uptake of molecular tritium (HT) by living pine needles. Soil and litter microbes convert HT to HTO more rapidly, but no measurable organic tritium is formed. This report discusses this study.
Date: February 16, 1982
Creator: Murphy, C.E. Jr.
Partner: UNT Libraries Government Documents Department

Nondestructive Assay of Uranium Enrichment with Gamma Rays

Description: An instrument has been developed and tested for nondestructive assay of 235U enrichment of uranium oxide powder contained in sealed 1-gallon cans. A theoretical correlation of enrichment vs. count rate agrees well with the calibration measurements and provides guidelines for applicability. A microcomputer simplifies operator requirements and provides on-line enrichment results.
Date: November 23, 1982
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Remote automatic plasma arc-closure welding of a dry-storage canister for spent nuclear fuel and high-level radioactive waste

Description: A carbon steel storage canister has been designed for the dry encapsulation of spent nuclear fuel assemblies or of logs of vitrified high level radioactive waste. The canister design is in conformance with the requirements of the ASME Code, Section III, Division 1 for a Class 3 vessel. The canisters will be loaded and sealed as part of a completely remote process sequence to be performed in the hot bay of an experimental encapsulation facility at the Nevada Test Site. The final closure to be made is a full penetration butt weld between the canister body, a 12.75-in O.D. x 0.25-in wall pipe, and a mating semiellipsoidal closure lid. Due to a combination of design, application and facility constraints, the closure weld must be made in the 2G position (canister vertical). The plasma arc welding system is described, and the final welding procedure is described and discussed in detail. Several aspects and results of the procedure development activity, which are of both specific and general interest, are highlighted; these include: The critical welding torch features which must be exactly controlled to permit reproducible energy input to, and gas stream interaction with, the weld puddle. A comparison of results using automatic arc voltage control with those obtained using a mechanically fixed initial arc gap. The optimization of a keyhole initiation procedure. A comparison of results using an autogenous keyhole closure procedure with those obtained using a filler metal addition. The sensitivity of the welding process and procedure to variations in joint configuration and dimensions and to variations in base metal chemistry. Finally, the advantages and disadvantages of the plasma arc process for this application are summarized from the current viewpoint, and the applicability of this process to other similar applications is briefly indicated.
Date: December 31, 1982
Creator: Sprecace, R.P. & Blankenship, W.P.
Partner: UNT Libraries Government Documents Department

Status of the Nevada Nuclear Waste Storage investigations

Description: The Nevada Nuclear Waste Storage Investigations (NNWSI) are part of the National Waste Terminal Storage (NWTS) program being conducted by the Department of Energy. Within the NWTS program, the NNWSI is the component that focuses on siting evaluations on and near the Nevada Test Site (NTS). The objectives of the Nevada project include evaluating the suitability of a Test and Evaluation Facility (TEF) site on or near the NTS, evaluating the suitability of a commercial nuclear waste repository site on or near the NTS, and supporting the NWTS program with research that is uniquely possible at NTS. Current engineering studies suggest that TEF and repository surface facilities would need to be located on gently sloping alluvium east of Yucca Mountain. Access from surface facilities to underground waste emplacement areas would be by vertical shafts and horizontal drifts, or possibly by inclined adits. The current NNWSI schedule includes an exploratory shaft location and horizon recommendation in 12/82, with a start of exploratory shaft drilling in 9/83. Because of the complexities of horizon selection, it is possible that the exploratory shaft depth or horizon recommendation may involve the exploration of more than one horizon. Phase I of the exploratory shaft, determination of TEF site suitability, is currently scheduled for 7/85. Phase II of the exploratory shaft, determination of repository site suitability, is currently scheduled for 3/87. This schedule is consistent with the current NWTS TEF and repository site selection schedules.
Date: January 1, 1982
Creator: Lincoln, R. C.
Partner: UNT Libraries Government Documents Department

Issues related to field testing in tuff

Description: 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.
Date: December 31, 1982
Creator: Zimmerman, R.M.
Partner: UNT Libraries Government Documents Department

Varietăţi Grassmanniene Mixte

Description: This article discusses mixed Grassmann manifolds. Abstract: Se construieşte varietea grassmanniană modelată intr-un spaţiu Banach mixt, situaţie ce generalizează simultan conceptele grassmanniene real şi complex.
Date: 1982
Creator: Anghel, Nicolae
Partner: UNT College of Arts and Sciences

M-shell x-ray production cross sections in thin targets of ₇₉Au, ₈₂Pb, ₈₃Bi, and ₉₂U by 0.3 - 2.6-MeV ₁¹H+ and ₂⁴He+ ions

Description: Article discussing M-shell x-ray-production cross sections in thin targets of ₇₉Au, ₈₂Pb, ₈₃Bi, and ₉₂U by 0.3 - 2.6-MeV ₁⁴H+ and ₂⁴He+ ions.
Date: October 1982
Creator: Mehta, R.; Duggan, Jerome L.; Price, J. L.; McDaniel, Floyd Del. (Floyd Delbert), 1942- & Lapicki, Gregory
Partner: UNT College of Arts and Sciences

Rapid isothermal anneal of 75As implanted silicon

Description: Article discussing a study of the rapid isothermal anneal of 75As implanted silicon.
Date: November 15, 1982
Creator: Wilson, Scott R.; Gregory, R. B.; Paulson, W. M.; Hamdi, A. H. & McDaniel, Floyd Del. (Floyd Delbert), 1942-
Partner: UNT College of Arts and Sciences

Thermal annealing behavior of an oxide layer under silicon

Description: This article discusses the thermal annealing behavior of an oxide layer under silicon.
Date: December 15, 1982
Creator: Hamdi, A. H.; McDaniel, Floyd Del. (Floyd Delbert), 1942-; Pinizzotto, Russell F.; Matteson, Samuel E.; Lam, H. W. & Malhi, S. D. S.
Partner: UNT College of Arts and Sciences

High-resolution x-ray scattering

Description: Beamline and spectrometer instrumentation for high-resolution x-ray scattering at the Stanford Synchrotron Radiation Laboratory is described. The combination of photon intensity at the sample of approx. 10/sup 13/ photons/sec/10 mm/sup 2/ and the momentum-transfer resolution of ..delta..Q approx. 10/sup -4/ A/sup -1/ make this a unique facility. Examples are given of data obtained on two-dimensional phase transitions both in studies of thin (2 molecular layers) liquid-crystal films and rare-gas monolayers on pyrolytic-graphite substrates.
Date: January 1, 1982
Creator: Moncton, D.E. & Brown, G.S.
Partner: UNT Libraries Government Documents Department

Fire and the related effects of nuclear explosions. 1982 Asilomar Conference

Description: This report summarizes the proceedings of a Federal Emergency Management Agency-sponsored Conference on fire and the related effects of nuclear explosions (with passing attention to earthquakes and other nonnuclear mishaps). This conference, the fifth of an annual series (formally called Blast/Fire Interaction Conferences), was held during the week of April 25, 1982, again at Asilomar, California.
Date: November 1, 1982
Creator: Martin, S.B. & Alger, R.S. (eds.)
Partner: UNT Libraries Government Documents Department

Dimension of chaotic attractors

Description: Dimension is perhaps the most basic property of an attractor. In this paper we discuss a variety of different definitions of dimension, compute their values for a typical example, and review previous work on the dimension of chaotic attractors. The relevant definitions of dimension are of two general types, those that depend only on metric properties, and those that depend on probabilistic properties (that is, they depend on the frequency with which a typical trajectory visits different regions of the attractor). Both our example and the previous work that we review support the conclusion that all of the probabilistic dimensions take on the same value, which we call the dimension of the natural measure, and all of the metric dimensions take on a common value, which we call the fractal dimension. Furthermore, the dimension of the natural measure is typically equal to the Lyapunov dimension, which is defined in terms of Lyapunov numbers, and thus is usually far easier to calculate than any other definition. Because it is computable and more physically relevant, we feel that the dimension of the natural measure is more important than the fractal dimension.
Date: September 1, 1982
Creator: Farmer, J.D.; Ott, E. & Yorke, J.A.
Partner: UNT Libraries Government Documents Department