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Identification of secondary phases formed during unsaturated reaction of UO{sub 2} with EJ-13 water

Description: A set of experiments, wherein UO{sub 2} has been contacted by dripping water, has been conducted over a period of 182.5 weeks. The experiments are being conducted to develop procedures to study spent fuel reaction under unsaturated conditions that are expected to exist over the lifetime of the proposed Yucca Mountain repository site. One half of the experiments have been terminated, while one half are ongoing. Analyses of solutions that have dripped from the reacted UO{sub 2} have been performed for all experiments, while the reacted UO{sub 2} surfaces have been examined for the terminated experiments. A pulse of uranium release from the UO{sub 2} solid, combined with the formation of schoepite on the surface of the UO{sub 2}, was observed between 39 and 96 weeks of reaction. Thereafter, the uranium release decreased and a second set of secondary phases was observed. The latter phases incorporated cations from the EJ-13 water and included boltwoodite, uranophane, sklodowskite, compreignacite, and schoepite. The experiments are continuing to monitor whether additional changes in solution chemistry or secondary phase formation occurs. 6 refs., 2 figs., 2 tabs.
Date: November 1, 1989
Creator: Bates, J.K.; Tani, B.S. & Veleckis, E.
Partner: UNT Libraries Government Documents Department

Parametric effects of glass reaction under unsaturated conditions

Description: Eventual liquid water contact of high-level waste glass stored under the unsaturated conditions anticipated at the Yucca Mountain site will be by slow intrusion of water into a breached container/canister assembly. The water flow patterns under these unsaturated conditions will vary, and the Unsaturated Test method has been developed by the YMP to study glass reaction. The results from seven different sets of tests done to investigate the effect of systematically varying parameters, such as glass composition, composition and degree of sensitization of 304L stainless steel, water input volume, and the interval of water contact are discussed. Glass reaction has been monitored over a period of five years, and the parametric effects can result in up to a ten-fold variance in the degree of glass reaction.
Date: November 1, 1989
Creator: Bates, J.K.; Gerding, T.J. & Woodland, A.B.
Partner: UNT Libraries Government Documents Department

Measurements of integrated water vapor and cloud liquid water from microwave radiometers at the DOE ARM Cloud and Radiation Testbed in the U.S. Southern Great Plains

Description: The operation and calibration of the ARM microwave radiometers is summarized. Measured radiometric brightness temperatures are compared with calculations based on the model using co-located radiosondes. Comparisons of perceptible water vapor retrieved from the radiometer with integrated soundings and co-located GPS retrievals are presented. The three water vapor sensing systems are shown to agree to within about 1 mm.
Date: June 1, 1996
Creator: Liljegren, J.C. & Lesht, B.M.
Partner: UNT Libraries Government Documents Department

The release of actinides, cesium, strontium, technetium, and iodine from spent fuel under unsaturated conditions

Description: Drip tests to measure radionuclide release from spent nuclear fuel are being performed at 90{degrees}C at a drip rate of 0.75 mL/3.5 days; the test conditions are designed to simulate the behavior of spent fuel under the unsaturated and oxidizing conditions expected in the potential repository at Yucca Mountain. This paper presents measurements of the actinide, {sup 137}Cs, {sup 90}Sr, {sup 99}Tc, and {sup 129}I contents in the leachates after 581 days of testing at 90{degrees}C. These values provide an estimate of the source term for the long-lived radionuclide release under these test conditions. Comparisons are made between our results and those of other researchers.
Date: December 1995
Creator: Finn, P. A.; Hoh, J. C. & Wolf, S. F.
Partner: UNT Libraries Government Documents Department

Crystal structure, short-range oxygen defects, and water adsorption in La- and Nd-modified ZrO{sub 2}

Description: Doping Rare-earth (RE) elements to ZrO{sub 2} helps stabilize the cubic and tetragonal phases and improves resistance to thermal shock and sintering at high temperatures. Since a RE ion has a lower valency (3{sup +}) than Zr ion (4{sup +}), oxygen vacancies are formed to preserve electroneutrality. We have studied the crystal structure of La{sub 0.1}Zr{sub 0.9}O{sub 1.95} and Nd{sub 0.1}Zr{sub 0.9}O{sub 1.95} by neutron diffraction and examined the associated oxygen defects by a Fourier transform of the filtered residual diffuse scattering. The hydration process was investigated by inelastic neutron-scattering measurements of the hydrogen vibrational density of states of the surface hydroxyl groups and physisorbed water on these fine powders. We compare the O-H stretch vibrations for samples from with only surface hydroxyl groups to multilayer coverage of water molecules. The decreasing energies and increasing widths of the O-H stretch bands with increasing H{sub 2}O coverage indicate the influence of hydrogen bonding on the motion of water molecules. Similar elastic and inelastic experiments were also performed on a high surface-area pure ZrO{sub 2} powder.
Date: February 1, 1995
Creator: Loong, C.K.; Richardson, J.W. Jr.; Iton, L.E. & Ozawa, M.
Partner: UNT Libraries Government Documents Department

Experimental and analytical study of condensation of ammonia-water mixtures

Description: The need for more energy efficient power generation and recent environmental issues of CFCs prompted the development of combined steam and Kalina cycle power systems, and advanced ammonia/water absorption heat pumps. However, the working media and associated thermal design aspects require new concepts for maintaining high thermal effectiveness and phase equilibrium for achieving maximum possible thermodynamic advantages. In the present study, a theoretical analysis was carried for the condensation of ammonia/water mixtures on a vertical tube. A set of equations was formulated and a calculation algorithm was developed to predict the local rate of heat and mass fluxes for binary ammonia-water systems. The predicted rate of condensation was compared with the experimental data obtained at Oak Ridge National Laboratory (ORNL) for a mixture of 90% ammonia and 10% water. The role of diffusion in simultaneous heat and mass transfer associated with condensation was analyzed by comparing the results from three limiting cases, which include equilibrium conditions, and liquid-phase diffusion of finite and infinite values. The results showed that the vapor-phase diffusion is a controlling mechanism.
Date: June 1, 1997
Creator: Panchal, C.B.; Kuru, W.C.; Chen, F.C.; Domingo, N. & HuangFu, E.P.
Partner: UNT Libraries Government Documents Department

Integrating O{sub 2} production with power systems to capture CO{sub 2}

Description: Chemical cycles for separating oxygen (O{sub 2}) from air were developed many years ago. These cycles involve initiating a reaction to capture O{sub 2} from the air and changing the operating conditions to effect a controlled breakdown of the newly formed product to release the O{sub 2} and regenerate the original species. Two such O{sub 2} separation cycles are the Moltox{trademark} and the barium oxide/peroxide cycles. These cycles are generally more expensive than more conventional methods--such as cryogenic separation of air--partly because they consume high-temperature thermal energy (500--850 C). Conventional air separation to produce O{sub 2}, though more economical than these cycles, is still too expensive when applied to combustion of fossil fuels. The nitrogen content of the combustion air results in a flue gas stream that is low in carbon dioxide (CO{sub 2}); this increases the complexity and cost of capturing the CO{sub 2} from the flue gas. These chemical cycles can be integrated with power cycles, such as the high-temperature gas turbine (1,300--1,500 C), to provide efficient heat cascading and recovery. The heat cascading process can also be arranged to minimize the overall exergy loss in the integrated system. The enriched O{sub 2} stream produced can be used in the combustion process to generate a CO{sub 2}-rich stream that is more readily separable for production of commercial-grade CO{sub 2}. This paper presents a discussion of air and water separation techniques integrated with power cycles.
Date: November 1, 1996
Creator: Jody, B.J.; Daniels, E.J. & Wolsky, A.M.
Partner: UNT Libraries Government Documents Department

Anomalous small angle x-ray scattering studies of heavy metal ion solvation behavior in clay minerals

Description: The authors have exploited anomalous small angle x-ray scattering (ASAXS) to monitor the solvation behavior of Cu(II), Er(III) and Yb(III) ions within the interlayers of the natural aluminosilicate clay mineral montmorillonite. The ASAXS technique can reveal the distribution of specific metallic species within a heterogeneous and disordered matrix. The variations of signal intensity as a function of absorption energy were monitored for all of the metal-clays as a function of hydration. Two different hydration levels were probed: as prepared at ambient conditions, or so-called {open_quotes}dry{close_quotes} powders, and {open_quotes}wet{close_quotes} pastes. ASAXS intensities should increase with absorption energy if the metal ion is associated with the interlayer solvent (water in this case), and decrease if the metal ion is associated with the solid matrix. The results show that: (1) Cu(II) is solvated within the interlayers of the wet sample, as expected, and (2) Er(III) and Yb(III) decrease in ASAXS intensity with increased hydration. This latter result was not expected and there is speculation that these ions have associated as hydrolyzed products with the clay surface. The basic principles underlying SAXS and ASAXS will also be presented in this paper.
Date: September 1, 1997
Creator: Carrado, K.A.; Thiyagarajan, P.; Winans, R.E. & Song, Kang
Partner: UNT Libraries Government Documents Department

Repository-relevant testing applied to the Yucca Mountain Project

Description: A repository environment poses a challenge to developing a testing program because of the diverse nature of conditions that may exist at a given time during the life of the repository. A starting point is to identify whether any potential waste-water contact modes are particularly deleterious to the waste form performance, and whether any interactions between materials present in the waste package environment need to be accounted for during modeling the waste form reaction. The Unsaturated Test method in one approach that has been developed by the Yucca Mountain Project (YMP) to investigate the above issues, and a description of results that have been obtained during the testing of glass and unirradiated UO{sub 2} are the subject of this report. 10 refs., 7 figs., 4 tabs.
Date: April 1, 1989
Creator: Bates, J.K.; Gerding, T.J. & Veleckis, E.
Partner: UNT Libraries Government Documents Department

Multicomponent three-phase equilibria

Description: This paper presents the relations that describe thermodynamic equilibrium in a three-phase system. Multiple components, including air, water, and oil components, are considered in three phases: (1) aqueous, (2) oil, and (3) gas. Primary variables are specified for each of seven possible phase combinations. These primary variables are then used to determine the necessary secondary variables to completely describe the system. Criteria are also developed to check the stability of each phase configuration and determine possible transitions from one phase configuration to another phase configuration via phase appearances and disappearances.
Date: June 1995
Creator: Ho, C. K.
Partner: UNT Libraries Government Documents Department

Multiple Rankine topping cycles

Description: The efficiency of a Rankine cycle is primarily determined by the temperatures of heat addition and rejection. However, no working fluid has been identified which will operate in a Rankine cycle over an extremely wide temperature range. Multiple Rankine topping cycles offer a technique for achieving high thermal efficiencies in power plants by allowing the use of several working fluids. This paper gives a history of Rankine topping cycles, presents an analysis for the calculation of the overall efficiency of a three-module multiple Rankine cycle, and presents results from a case study for a sodium-mercury-water cycle.
Date: July 1, 1995
Creator: McWhirter, J.D.
Partner: UNT Libraries Government Documents Department

Modelling absorption and dilution of unconfined releases of hazardous gases by water curtains or monitors

Description: OSHA Process Safety Management guidelines suggest that a facility operator investigate and document a plan for installing systems to detect, contain, or mitigate accidental releases if such systems are not already in place. In addition, proposed EPA 112(r) regulations would require such analysis. This paper illustrates how mathematical modelling can aid such an evaluation and describes some recent enhancements of the HGSPRAY model: (1) Adding algorithms for modeling NH{sub 3} and LNG mitigation; (2) Modeling spraying of releases with fire water monitors encircling the point of release; (3) Combining wind tunnel modeling with mathematical modeling; and (4) Linking HGSPRAY and BEGADAS. Case cases are presented as examples of how HGSPRAY can aid the design of water spray systems for initiation of toxic gases (e.g., BF, NH,) or dilution/dispersion of flammable vapors (e.g., LNG).
Date: May 1, 1995
Creator: Fthenakis, V.M.; Blewitt, D.N. & Hague, W.J.
Partner: UNT Libraries Government Documents Department

Development of a coal fired pulse combustor for residential space heating. Technical progress report, April--June 1987

Description: During this period, advanced chambers were fabricated and tested in both single and tandem configurations. A scrubber was designed, constructed, installed in the facility, and checked-out. The dry pulverized coal and micronized coal water mixtures have been supplied by Energy International. Optimization of the configuration continued with respect to fuel phasing, slag handling characteristics, and tailpipe coupling.
Date: December 31, 1987
Partner: UNT Libraries Government Documents Department

Heat transfer studies. Quarterly report

Description: Nitrogen gas has been used in experimental studies related to understanding issues in the extension of multi-phase models to sub-residual saturation conditions during drying. Two different flow rates of 1 SLPM and 0.5 SLPM with a room temperature boundary condition on the aluminum column have been examined. Information about variations of humidity and temperatures is given. It is shown that the situation that exists in the experiments is somewhat different than that found in typical assumptions made by numerical modelers. Work planned for the next quarter is outlined. The apparatus used for the work noted above will be supplemented to allow other temperature conditions than ambient to be evaluated. Temperatures up to 90{degree}C will be used. Other work planned for the next period will involve the use of small-scale simulated repository experiment to determine temperatures and humidities around a horizontal heater within an annulus in a rigid porous medium. The effect of backfill on performance when episodic flows are encountered will be compared to results when backfill is not present (the latter results have been determined earlier).
Date: July 20, 1995
Creator: Boehm, R.; Chen, Y.T. & Vallebuona, J.
Partner: UNT Libraries Government Documents Department

Process and economic model of in-field heavy oil upgrading using aqueous pyrolysis

Description: A process and economic model for aqueous pyrolysis in-field upgrading of heavy oil has been developed. The model has been constructed using the ASPEN PLUS chemical process simulator. The process features cracking of heavy oil at moderate temperatures in the presence of water to increase oil quality and thus the value of the oil. Calculations with the model indicate that for a 464 Mg/day (3,000 bbl/day) process, which increases the oil API gravity of the processed oil from 13.5{degree} to 22.4{degree}, the required value increase of the oil would need to be at least $2.80/Mg{center_dot}{degree}API($0.40/bbl{center_dot}{degree}API) to make the process economically attractive. This level of upgrading has been demonstrated in preliminary experiments with candidate catalysts. For improved catalysts capable of having the coke make and increasing the pyrolysis rate, a required price increase for the oil as low as $1.34/Mg{center_dot}{degree}API ($0.21/bbl{center_dot}{degree}API)has been calculated.
Date: January 21, 1997
Creator: Thorsness, C. B., LLNL
Partner: UNT Libraries Government Documents Department

Non-equilibrium fluid flow around the Yucca Mountain Nuclear Waste Repository

Description: The results of this study are consistent with the G-Tunnel test results, which indicated no water bank forming above the dry zone, and differ from the simulation results based on the equivalent continuum model (ECM), which indicated a water bank may form above the dry zone. The reason that the simulation studies predict the creation of a water bank is that the ECM assumes capillary equilibrium between the fractures and matrix. This study quantified the non-equilibrium fluid flow between the fractures and matrix and has shown that water entering the fractures above the dry zone will drain away from the repository before capillary equilibrium could be created. Thus, the ECM models are inappropriate for many studies of water transport around the proposed Yucca Mountain repository. It is noted that the authors of the ECM studies recognized this limitation and recommended that the more difficult non-equilibrium studies be conducted. It is concluded that a significant water bank above the repository from the redistribution of water from nuclear decay heating is unlikely. Thus, the integrity of the repository is not expected to-be threatened by rewetting of the formation from a water bank.
Date: August 1, 1995
Creator: Reis, J.C.
Partner: UNT Libraries Government Documents Department

Selenium isotope geochemistry: A new approach to characterizing the environmental chemistry of selenium. Final report

Description: High levels of selenium in the environment will be a prominent water quality issue in the western United States for many years. Selenium accumulation is linked to increased rates of death and deformity in migratory birds, blind staggers in livestock, and selenosis in humans. In California, agricultural drain waters and oil refinery effluent contribute to high selenium content in the San Joaquin Valley and the San Francisco Bay. The importance of these industries to California`s economy precludes simple abatement, while the complexity of selenium cycling precludes simple remediation. The purpose of this project is to measure variations in the isotopic composition of selenium in water and soil samples caused by natural processes and to show, for the first time, the value of isotopic measurements in characterizing selenium pollution. The research seeks to identify sources of selenium pollution, determine processes in the selenium cycle, and support selenium remediation studies. The project required the successful integration of three components: (1) appropriate sampling a field setting showing Se enrichment and possibly isotopic fractionation, (2) analytical chemical methods for isolating and purifying the various species of Se in waters and sediment, and (3) mass spectroscopic instrumentation for high precision isotope abundance measurements.
Date: February 5, 1997
Creator: Volpe, A.M. & Esser, B.K.
Partner: UNT Libraries Government Documents Department

Limitations for heterodyne detection of Brillouin scattered light

Description: One means by which elastic properties of a material may be determined is measuring sound wave velocities in the material, from which elastic moduli of interest can be computed. Velocity can be measured by conventional piezoelectric transduction techniques, by applying laser ultrasonics, or by using Brillouin-scattering methods. Brillouin-scattering techniques for determining the sound wave velocity are particularly attractive since they are completely noninvasive. Only a probe beam of light is required since the thermal energy in the material provides the elastic motion. Heterodyne methods for detection of Brillouin-scattered light are considered one possible means to increase the speed of the scattered light frequency detection. Results of experiments with simulated Brillouin scattering suggest that heterodyne detection of the Brillouin-scattered light is feasible. Experiments to detect Brillouin-scattered light, with water as the scattering medium, were designed and interpreted using the results of the simulated scattering experiments. Overall, results showed that it is difficult to narrow the linewidth for Brillouin scattering to an acceptable level. The results given indicate that heterodyne detection of the Brillouin components requires detection bandwidths that are quite small, perhaps 10 Hz or lower. These small bandwidths can be routinely achieved using lock-in amplifier techniques.
Date: January 1, 1995
Creator: Allemeier, R.T.; Wagner, J.W. & Telschow, K.L.
Partner: UNT Libraries Government Documents Department

The Europa Ocean Discovery mission

Description: Since it was first proposed that tidal heating of Europa by Jupiter might lead to liquid water oceans below Europa`s ice cover, there has been speculation over the possible exobiological implications of such an ocean. Liquid water is the essential ingredient for life as it is known, and the existence of a second water ocean in the Solar System would be of paramount importance for seeking the origin and existence of life beyond Earth. The authors present here a Discovery-class mission concept (Europa Ocean Discovery) to determine the existence of a liquid water ocean on Europa and to characterize Europa`s surface structure. The technical goal of the Europa Ocean Discovery mission is to study Europa with an orbiting spacecraft. This goal is challenging but entirely feasible within the Discovery envelope. There are four key challenges: entering Europan orbit, generating power, surviving long enough in the radiation environment to return valuable science, and complete the mission within the Discovery program`s launch vehicle and budget constraints. The authors will present here a viable mission that meets these challenges.
Date: June 1, 1997
Creator: Edwards, B.C.; Chyba, C.F. & Abshire, J.B.
Partner: UNT Libraries Government Documents Department

Electrolytic production of hydrogen utilizing photovoltaic cells

Description: Hydrogen has the potential to serve as both an energy storage means and an energy carrier in renewable energy systems. When renewable energy sources such as solar or wind power are used to produce electrical power, the output can vary depending on weather conditions. By using renewable sources to produce hydrogen, a fuel which can be stored and transported, a reliable and continuously available energy supply with a predictable long-term average output is created. Electrolysis is one method of converting renewable energy into hydrogen fuel. In this experiment we examine the use of an electrolyzer based on polymer-electrolyte membrane technology to separate water into hydrogen and oxygen. The oxygen is vented to the atmosphere and the hydrogen is stored in a small pressure vessel.
Date: October 1, 1996
Creator: Daugherty, M.A.
Partner: UNT Libraries Government Documents Department

Synthesis report on thermally driven coupled processes

Description: The main purpose of this report is to document observations and data on thermally coupled processes for conditions that are expected to occur within and around a repository at Yucca Mountain. Some attempt is made to summarize values of properties (e.g., thermal properties, hydrologic properties) that can be measured in the laboratory on intact samples of the rock matrix. Variation of these properties with temperature, or with conditions likely to be encountered at elevated temperature in the host rock, is of particular interest. However, the main emphasis of this report is on direct observation of thermally coupled processes at various scales. Direct phenomenological observations are vitally important in developing and testing conceptual models. If the mathematical implementation of a conceptual model predicts a consequence that is not observed, either (1) the parameters or the boundary conditions used in the calculation are incorrect or (2) the conceptual basis of the model does not fit the experiment; in either case, the model must be revised. For example, the effective continuum model that has been used in thermohydrology studies combines matrix and fracture flow in a way that is equivalent to an assumption that water is imbibed instantaneously from fractures into adjacent, partially saturated matrix. Based on this approximation, the continuum-flow response that is analogous to fracture flow will not occur until the effective continuum is almost completely saturated. This approximation is not entirely consistent with some of the experimental data presented in this report. This report documents laboratory work and field studies undertaken in FY96 and FY97 to investigate thermally coupled processes such as heat pipes and fracture-matrix coupling. In addition, relevant activities from past years, and work undertaken outside the Yucca Mountain project are summarized and discussed. Natural and artificial analogs are also discussed to provide a convenient source of material ...
Date: October 15, 1997
Creator: Hardin, E.L.
Partner: UNT Libraries Government Documents Department