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The Levi problem on mixed manifolds

Description: Article discussing the Levi problem on mixed manifolds. This article gives a new proof that the problem of Levi, to mixed varieties have a solution in the sense that every pseudoconvex closely mixed variety, with enough real global morphisms, is a variety of Cartan.
Date: 1984
Creator: Anghel, Nicolae
Partner: UNT College of Arts and Sciences

NRL capillary Z-pinch experiment

Description: The current renewed interest in the dense linear z-pinch is due in large part to a recent Los Alamos Study which concluded that a z- pinch based reactor could produce 4.4 KJ of fusion energy per pulse for the modest input of 140 kJ per pulse, if a straight pinch could be maintained for 2 {mu}sec. Early attempts to achieve suitable high density z-pinches were of the implosion type which produced hollow pressure profiles that quickly resulted in disruptive m = 0 instabilities. These instabilities are not found in the gas embedded pinch in which an initially small diameter plasma is kept in radial equilibrium by following a prescribed current waveform. Unfortunately, these pinches are prone to a rapid accretion of the surrounding gas during the early stages of formation. Our approach is to form the pinch inside small diameter quartz capillaries filled with neutral hydrogen. This fixes the line density. By driving currents through the pinch at a rate that exceeds that necessary for radial equilibrium, we expect the pinch to contract away from the walls and be subject to compressional, as well as ohmic heating. This contraction will, of course, produce a plasma between the pinch and the capillary wall, but we anticipate this ``corona`` will be kept at a low temperature (i.e., high resistance) by radiation and hence shunt only a small fraction of the pinch current. We also expect negligible impurities in the pinch as the classical mixing time will be much longer than the pinch duration at the densities (10{sup 21}- 10{sup 22} ions/cm{sup 3}) and magnetic fields (1 - 10 MG) involved. However, we do expect the presence of the dense corona to reduce the growth rate of the m = 1 instability. Our results demonstrate that a z-pinch can be formed inside a ...
Date: December 31, 1984
Creator: Sethian, J.D.; Gerber, K.A.; Robson, A.E. & DeSilva, A.W.
Partner: UNT Libraries Government Documents Department

Overview of geochemical modeling needs for nuclear waste management

Description: Research needs include, but are not limited to: measurement of basic thermodynamic data at elevated temperatures for species identified by modelers as potentially important; evaluation of substances which control or limit precipitation and/or nucleation kinetics; sorption studies specifically designed to provide data needed for modeling. This includes the rate of sorption, desorption, and the characterization of the solid and aqueous phases; site-mixing models and thermodynamic data for secondary minerals that form solid solutions; the development of standard techniques for measuring rate laws for precipitation and dissolution kinetics; and measurement of rate laws describing redox kinetics, dissolution, and precipitation involving aqueous species and solid phases of interest to geochemical modelers.
Date: May 25, 1984
Creator: Isherwood, D. & Wolery, T.
Partner: UNT Libraries Government Documents Department

NNWSI waste form performance test development

Description: A test method has been developed to measure the release of radionuclides from the waste package under simulated NNWSI repository conditions, and to provide information concerning materials interactions that may occur in the repository. Data from 13 weeks of unsaturated testing are discussed and compared to that from a 13-week analog test. The data indicate that the waste form test is capable of producing consistent, reproducible results that will be useful in evaluating the role of the waste in the long-term performance of the repository. 6 references, 3 figures.
Date: December 31, 1984
Creator: Bates, J.K. & Gerding, T.J.
Partner: UNT Libraries Government Documents Department

Comparison of potential health and safety impacts of different disposal options for defense high-level wastes

Description: A comparative assessment has been performed of the potential long- and short-term health and safety impacts of different disposal options for defense high-level wastes. Conservative models and assumptions were used. The assessment suggests that considerations of health and safety will not be significant in choosing among disposal options, primarily because of the need to meet stringent standards in all cases. Rather, the ease and cost of assuring compliance of a particular disposal option with health and safety standards may be a more important factor. 11 references.
Date: December 31, 1984
Creator: Kocher, D.C.; Smith, E.D. & Witherspoon, J.P.
Partner: UNT Libraries Government Documents Department

Modeling of strongly heat-driven flow in partially saturated fractured porous media

Description: We have performed modeling studies on the simultaneous transport of heat, liquid water, vapor, and air in partially saturated fractured porous media, with particular emphasis on strongly heat-driven flow. The presence of fractures makes the transport problem very complex, both in terms of flow geometry and physics. The numerical simulator used for our flow calculations takes into account most of the physical effects which are important in multi-phase fluid and heat flow. It has provisions to handle the extreme non-linearities which arise in phase transitions, component disappearances, and capillary discontinuities at fracture faces. We model a region around an infinite linear string of nuclear waste canisters, taking into account both the discrete fractures and the porous matrix. From an analysis of the results obtained with explicit fractures, we develop equivalent continuum models which can reproduce the temperature, saturation, and pressure variation, and gas and liquid flow rates of the discrete fracture-porous matrix calculations. The equivalent continuum approach makes use of a generalized relative permeability concept to take into account for fracture effects. This results in a substantial simplification of the flow problem which makes larger scale modeling of complicated unsaturated fractured porous systems feasible. Potential applications for regional scale simulations and limitations of the continuum approach are discussed. 27 references, 13 figures, 2 tables.
Date: October 1, 1984
Creator: Pruess, K.; Tsang, Y.W. & Wang, J.S.Y.
Partner: UNT Libraries Government Documents Department

EQ3/6: status and applications

Description: EQ3/6 is a set of related computer codes and data files for use in geochemical modeling of aqueous systems. The EQ3/6 package centers around two large computer codes, EQ3NR and EQ6, which are supported by a common thermodynamic data base. EQ3NR is a speciation-solubility code, whose function is to compute a model of the state of an aqueous solution. This code is very flexible in terms of the input that it will accept. EQ6 is a reaction-path code, which calculates models of changes in aqueous systems as they proceed toward a state of overall chemical equilibrium. EQ3/6 prior to FY83 had no capability for modeling brines, because the approximations for calculating the thermodynamic activity of water and the activity coefficients of the solute species were restricted to low ionic strengths ({le} 1.0 molal). An option has been added to use Pitzer`s equations for such calculations. At present, EQ3/6 contains two alternate Pitzer coefficient data bases. Several improvements have been made to the EQ6 code. Prior to FY83, the code could run models of mineral dissolution kinetics, but could not calculate models of precipitation kinetics. This problem has been overcome by additional code development. The speed of non-kinetic EQ6 calculations has recently been enhanced by the creation of two new calculational modes, economy mode and super economy mode. A calculational mode to simulate systems open to large gas reservoirs has also been developed. 34 references.
Date: December 1, 1984
Creator: Wolery, T.J.; Isherwood, D.J.; Jackson, K.J.; Delany, J.M. & Puigdomenech, I.
Partner: UNT Libraries Government Documents Department

Thermal modeling of nuclear waste package designs for disposal in tuff

Description: Lawrence Livermore National Laboratory is involved in the design and testing of high-level nuclear waste packages. Many of the aspects of waste package design and testing (e.g., corrosion and leaching) depend in part on the temperature history of the emplaced packages. This paper discusses thermal modeling and analysis of various emplaced waste package conceptual designs including the models used, the assumptions and approximations made, and the results obtained. 6 references, 6 figures, 4 tables.
Date: February 1, 1984
Creator: Hockman, J.N. & O`Neal, W.C.
Partner: UNT Libraries Government Documents Department

Contact zones and hydrothermal systems as analogues to repository conditions

Description: Radioactive waste isolation efforts in the US are currently focused on examining basalt, tuff, salt, and crystalline rock as candidate rock types to encompass waste repositories. As analogues to near-field conditions, the distributions of radio- and trace-elements have been examined across contacts between these rocks and dikes and stocks that have intruded them. The intensive study of the Stripa quartz monzonite has also offered the opportunity to observe the distribution of uranium and its daughters in groundwater and its relationship to U associated with fracture-filling and alteration minerals. Investigations of intrusive contact zones to date have included (1) a tertiary stock into Precambrian gneiss, (2) a stock into ash flow tuff, (3) a rhyodacite dike into Columbia River basalt, and (4) a kimberlite dike into salt. With respect to temperature and pressure, these contact zones may be considered "worst-case scenario" analogues. Results indicate that there has been no appreciable migration of radioelements from the more radioactive intrusives into the less radioactive country rocks, either in response to the intrusions or in the fracture-controlled hydrological systems that developed following emplacement. In many cases, the radioelements are locked up in accessory minerals, suggesting that artificial analogues to these would make ideal waste forms. Emphasis should now shift to examination of active hydrothermal systems, studying the distribution of key elements in water, fractures, and alteration minerals under pressure and temperature conditions most similar to those expected in the near-field environment of a repository. 14 refs.
Date: October 1, 1984
Creator: Wollenberg, H.A. & Flexser, S.
Partner: UNT Libraries Government Documents Department

Spent fuel cladding containment credit tests

Description: Preliminary tests are being conducted to evaluate the effectiveness of defected cladding as a barrier to radionuclide release from spent fuel rods stored in a geological repository. The tests are being conducted at the Hanford Engineering Development Laboratory Waste Package Task of the Nevada Nuclear Waste Storage Investigations (NNWSI) tuff repository project. In these tests, spent PWR fuel rod specimens with various artificially induced cladding defects are leach tested in a test matrix which also includes both bare fuel specimens (unclad) and undefected spent fuel rod specimens. Artificial cladding defects are made by laser drilling and sawing to give defect areas in the 10{sup 4} to 10{sup 6} {mu}m{sup 2} range. Periodic samples are taken of the leach solution and fused quartz rods contained in the test vessels. Results for the first 180 days of testing are presented. 5 references, 3 figures, 2 tables.
Date: February 1, 1984
Creator: Wilson, C.N. & Oversby, V.M.
Partner: UNT Libraries Government Documents Department

Ultrasound: Biological Effects and Industrial Hygiene Concerns

Description: This paper discusses biological effects associated with overexposure to ultrasound, exposure standards proposed for airborne and contact ultrasound, industrial hygiene controls that can be employed to minimize exposure, and the instrumentation that is required for evaluating exposures.
Date: December 3, 1984
Creator: Wiernicki, C.
Partner: UNT Libraries Government Documents Department

Improved Uranium Recovery from the Process Streams in an Electroplating Facility

Description: This report discusses results of testing to improve uranium recovery from the process streams in an electroplating facility. Cylindrical uranium slugs are used as irradiation targets in the production reactors at the Savannah River Plant. These slugs are first chemically etched, nickel plated, encased in aluminum, inspected, and individually pressure tested. An improved process was developed to recover the uranium from the acidic etching streams for controlling pH and the PO4 to U ratio so that the precipitation of the uranium as hydrogen uranyl phosphate was maximized.
Date: November 21, 1984
Creator: Pickett, J.B.
Partner: UNT Libraries Government Documents Department

Control of Oxidation Potential for Basalt Repository Simulation Tests

Description: Borosilicate waste glass durability in simulated repository environments can be assessed by use of static tests in leach vessels fabricated of the representative geomedia. Control of the oxidation potential during the test simulates a basalt repository environment. Under very anoxic conditions (i.e., at negative Eh values) the interactions between basalt and SRP waste glass in silica-saturated basaltic groundwaters are the same as those of basalt and groundwater when no waste glass is present. The lack of significant leaching of ions from the waste glass and the lack of any significant changes in either the leached surfaces of glass or basalt under anoxic conditions suggests that the components of this system are at equilibrium when oxygen is absent.
Date: November 13, 1984
Creator: Jantzen, C.M.
Partner: UNT Libraries Government Documents Department

International Waste Glass Study - Composition and Leachability Correlations

Description: As part of an effort to assess and understand the performance and chemical durability of Savannah River Plant (SRP) waste glass, an International Glass Study was undertaken. That study found important similarities, based on correlations of composition and leaching performance, among many difference defense and commercial waste glass compositions being studied world-wide. In addition, the beneficial effect of waste on glass performance was confirmed for the systems evaluated. This paper discusses those results.
Date: November 21, 1984
Creator: Wicks, G. G.
Partner: UNT Libraries Government Documents Department

Comparison of Predicted Offsite Doses with Measured Doses at the Savannah River Plant

Description: An automated emergency response system for real-time predictions of offsite dose from unplanned atmospheric releases of radioactivity is maintained at the Savannah River Plant. The system consists of a minicomputer and associated peripherals necessary for acquisition and handling of large amounts of meteorological data from a local tower network and the National Weather Service. The minicomputer uses these data and predictive models to assess the impact of accidental releases. The dose estimates from this system were compared to measured doses from bioassay samples on several occasions when unplanned releases of tritium have occurred. On all occasions the calculated doses showed good agreement with the measured doses.
Date: November 1, 1984
Creator: Zeigler, C.C.
Partner: UNT Libraries Government Documents Department

Uranium Density and Enrichment in Fuel Tubes Determined from 232U and 235U Y-Activities

Description: Gamma spectroscopy is used to determine 235U density and enrichment in U-Al fuel tubes containing recycled fuel. A collimated HPGe Y-detector views the tube surface, such that U-Al disk volumes of 6.35 mm diameter and approximately 1.0 mm thickness are examined. The Y-activities from 232U and 235U, along with the tube design parameters, are used to deduce the attenuation-corrected results. Respective density and enrichment variations of less than 1 percent and less than 0.6e percent were measurable with 2000 sec counting time per tube location. Such measurements are useful for certifying tube quality and characterizing problems associated with blending the U-Al alloy.
Date: May 25, 1984
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Leaching of Devitrified Glass Containing Simulated SRP Nuclear Waste

Description: Time-temperature transformation curves have been determined for SRL-165 and SRL-131 waste glasses for all potential waste compositions. SRL-165 glasses, which contain less alkali, exhibit less complex devitrification and higher overall durability than SRL-131 waste glasses. Devitrification was found to have less effect on the durability of waste glasses than changes in composition. Non-uniform dissolution at the glass leached layer interface is observed. However, leached layers formed after 28 days shield the crystal interfaces from further dissolution.
Date: November 19, 1984
Creator: Jantzen, C.M.
Partner: UNT Libraries Government Documents Department

Physical Properties of Saltstone: A Savannah River Plant Waste Form

Description: A cement-based waste form, ''saltstone'', has been designed for disposal of Savannah River Plant low-level radioactive salt waste. Laboratory and field tests indicate that this stabilization process greatly reduces the mobility of all of the waste constituents in the surface and near-surface environment. Bulk properties of this material have been tailored with respect to salt leach rate, permeability, and compressive strength. Microstructure and mineralogy were characterized by SEM and X-ray diffraction analyses. Compressive strength was found to increase as the water to cement ratio decreased. Porosity and mean pore size increased with increasing water to cement ratios. Bulk diffusivities of the various ions dissolved in the pore solutions were also found to increase as water to cement ratios increased. This paper discusses the test results.
Date: November 26, 1984
Creator: Langston, C.A.
Partner: UNT Libraries Government Documents Department

Behavior of carbon-14 in waste packages for spent fuel in a repository in tuff. Revision 1

Description: Analysis of gas from a heated air-filled canister containing a spent fuel assembly before and after rupture of a fuel rod shows that about 1.5 mCi of {sup 14}C from the external surface of the assembly was rapidly oxidized and released as {sup 14}CO{sub 2} in excess oxygen at 275{sup 0}C and 10{sup 4}/sup rad/h. After rupture, an additional 0.3 mCi was released, probably also from the external surface. The total {sup 14}C inventory in the entire 15 x 15 rod assembly including structural hardware is estimated to be 690 mCi. These measurements indicate that account will have to be taken of the time distribution of lifetimes of the canisters, and a broad definition of the "engineered system" may be necessary, in order to meet 10CFR60 requirements with spent fuel in a repository in tuff. 22 refs., 1 tab.
Date: November 7, 1984
Creator: Van Konynenburg, R.A.; Smith, C.F.; Culham, H.W. & Otto, C.H. Jr.
Partner: UNT Libraries Government Documents Department

Nuclear waste package design for the Vadose zone in tuff

Description: This report presents an overview of the selection and analysis of conceptual waste package designs that will be used by the Nevada Nuclear Waste Storage Investigations (NNWSI) project for disposal of high-level nuclear waste (HLW) at the proposed Yucca Mountain, Nevada Site. The design requirements that the waste packages are required to meet are listed. Concept drawings for the reference designs and one alternative package design are shown. Four metal alloys; 304L SS, 321 SS, 316L SS and Incoloy 825 have been selected for candidate canister/overpack materials, and 1020 carbon steel has been selected as the reference metal for the borehole liners. A summary of the results of technical and economic analysis supporting the selection of the conceptual waste package designs is included. Post-closure containment and release rates are not discussed in this paper. 17 references, 2 figures, 2 tables.
Date: February 1, 1984
Creator: O`Neal, W.C.; Ballou, L.B.; Gregg, D.W. & Russell, E.W.
Partner: UNT Libraries Government Documents Department