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Zirconia Solubility in Boroaluminosilicate Glass
In the Idaho Chemical Processing Plant (ICPP) waste streams, zirconia is often the waste load limiting species. It modifies the glass network, enhances durability, increases viscosity and induces crystallization. The limits of its dissolution in boroaluminosilicate glass, with magnesia and soda additions were experimentally determined. A ternary compositional surface is evolved to present the isothermal regimes of liquid, liquid + zircon, liquid + forsterite, and liquid phase sintered ceramic. The potential of partitioning the transuranics, transition elements and solutes in these regimes is discussed. The visible Raman spectroscopic results are presented to elucidate the dependence among glass composition, structure and chemical durability.
Date:
December 31, 1995
Creator:
Raman, S. V.; Bopp, R.; Batcheller, T. A. & Yan, Q.
Object Type:
Report
System:
The UNT Digital Library
Zirconia toughened alumina reticulated foam filters. Quarterly report, October 1--December 31, 1997
Work during this period focused on making foam and membrane samples from the ceria zirconia toughened alumina developed in the previous SBIR program. After some adjustment very strong samples which have reasonably good working characteristics. The initial pressure drop measurements through the membrane suggest that it will need to be made with a more open structure.
Date:
December 31, 1997
Creator:
Buthcer, K.
Object Type:
Report
System:
The UNT Digital Library
Zirconium and Technetium Recovery and Partitioning in the Presence of Actinides in Modified Purex Process for ATW Program. Final Report
The modified Purex process flowsheet is based on combination of all irradiated materials, their joint dissolution and reprocessing as a NPP spent fuel solution with abnormal Pu content after addition of recycled depleted U concentrate. Some groups of long-lived radionuclides could be completely recovered and localized at the stage of extraction reprocessing using 30% TBP. Studies were conducted for 10 y to develop the process for recovery, concentration, and localization of U, Pu, Np, Tc, and Zr within 1st extraction cycle. Actinides are recovered from high-level raffinate of this cycle after evaporation and feed adjustment. Results in this report show that combined deep recovery of several elements from highly irradiated materials by TBP extraction, for further transmutation, is possible. Selective stripping of Zr from solvent phase containing U, Pu, Np, and Tc is quite effective. Development of the modified Purex process is not complete; main problem to be solved should be oxide separation from the loop and permissible storage duration before reprocessing and reuse in the loop.
Date:
December 31, 1994
Creator:
Dzekun, E. G.; Fedorov, Y. S.; Galkin, B. Y.; Lyubtsev, R. I.; Mashkin, A. N.; Mishin, E. N. et al.
Object Type:
Report
System:
The UNT Digital Library
Zirconium phosphate waste forms for low-temperature stabilization of cesium-137-containing waste streams
Novel chemically bonded phosphate ceramics are being developed and fabricated for low-temperature stabilization and solidification of waste streams that are not amenable to conventional high-temperature stabilization processes because volatiles are present in the wastes. A composite of zirconium-magnesium phosphate has been developed and shown to stabilize ash waste contaminated with a radioactive surrogate of {sup 137}Cs. Excellent retainment of cesium in the phosphate matrix system was observed in Toxicity Characteristic Leaching Procedure tests. This was attributed to the capture of cesium in the layered zirconium phosphate structure by intercalation ion-exchange reaction. But because zirconium phosphate has low strength, a novel zirconium/magnesium phosphate composite waste form system was developed. The performance of these final waste forms, as indicated by compression strength and durability in aqueous environments, satisfy the regulatory criteria. Test results indicate that zirconium-magnesium-phosphate-based final waste forms present a viable technology for treatment and solidification of cesium-contaminated wastes.
Date:
April 1, 1996
Creator:
Singh, D.; Wagh, A.S. & Tlustochowicz
Object Type:
Article
System:
The UNT Digital Library
Zirconium-titanium phosphate acid catalysts synthesized by sol gel techniques
Recently a large effort has been put into identifying solid acid materials, particularly sulfated zirconia and other sulfated metal oxides, that can be used to replace environmentally hazardous liquid acids in industrial processes. The authors are studying a group of mixed metal phosphates, some of which have also been sulfated, for their catalytic and morphological characteristics. Zirconium and titanium are the metals used in this study and the catalysts are synthesized from alkoxide starting materials with H{sub 3}PO{sub 4}, H{sub 2}O, and sometimes H{sub 2}SO{sub 4} as gelling agents. The measurement of acidity was achieved by using the isomerization of 2-methyl-2-pentene as a model reaction. The phosphate stabilized the mixed metal sulfates, preventing them from calcining to oxides boosting their initial catalytic activity. The addition of sulfate prevented the formation of the catalytically inactive mixed metal pyrophosphates when calcined at high temperatures (> 773 K).
Date:
March 1, 1998
Creator:
Jackson, N. B.; Thoma, S. G.; Kohler, S. & Nenoff, T. M.
Object Type:
Article
System:
The UNT Digital Library
Zircons and fluids: An experimental investigation with applications for radioactive waste disposal
The long-term stability of nuclear waste forms or barriers is related to changes in physical properties of the material induced through radiation damage and subsequent changes in solubility. Investigations conducted by us on natural zircons (ZrSiO{sub 4}) supports a positive correlation between level of alpha damage and fluid composition to enhanced levels of corrosion. New data are presented on the nature and rate of the solution process. We also present data on our continuing efforts to synthesize and characterize both pure ZrSiO{sub 4} and doped with U, Th, Hf, Dy and P.
Date:
1992~
Creator:
Sinha, A.K.; Student, J. & Essex, R.
Object Type:
Report
System:
The UNT Digital Library
Zircons and fluids: An experimental investigation with applications for radioactive waste disposal. Stability of zircons: Progress report, January 1992--December 1992
The long-term stability of nuclear waste forms or barriers is related to changes in physical properties of the material induced through radiation damage and subsequent changes in solubility. Investigations conducted on natural zircons (ZrSiO{sub 4}) supports a positive correlation between level of alpha damage and fluid composition to enhanced levels of corrosion. In this report we present preliminary data on the nature and rate of the solution process involving < 600,000 year-old zircons being affected by natural fluids in geyser fields of Yellowstone National Park. We also summarize our continuing activity by including in this report articles that have been published or are in press in refereed journals.
Date:
1993~
Creator:
Sinha, A. K.
Object Type:
Report
System:
The UNT Digital Library
Zircons and fluids: An experimental investigation with applications for radioactive waste storage. Final report, July 1, 1988--July 31, 1994
The project objective was to develop a relationship between the stability of zircons (both natural and synthetic) with variable levels of radiation damage to fluids because of the clear relationship between enhanced solubility (leachability) and {alpha} - damage, our research was able to quantify this process. We also analyzed the mechanics of fractures induced due to both radiation and temperature enhanced stresses. Both objective were successfully carried out, and although details are available in progress reports and referred publications, a brief summary is presented here.
Date:
May 1, 1998
Creator:
Sinha, A.K.
Object Type:
Report
System:
The UNT Digital Library
Zlib: A numerical library for optimal design of truncated power series algebra and map parameterization routines
A brief review of the Zlib development is given. Emphasized is the Zlib nerve system which uses the One-Step Index Pointers (OSIPs) for efficient computation and flexible use of the Truncated Power Series Algebra (TPSA). Also emphasized is the treatment of parameterized maps with an object-oriented language (e.g. C++). A parameterized map can be a Vector Power Series (Vps) or a Lie generator represented by an exponent of a Truncated Power Series (Tps) of which each coefficient is an object of truncated power series.
Date:
November 1, 1996
Creator:
Yan, Y.T.
Object Type:
Article
System:
The UNT Digital Library
ZLIB++: Object-oriented numerical library for differential algebra
New software engineering tools and object-oriented design have a great impact on the software development process. But in high energy physics all major packages were implemented in FORTRAN and porting of these codes to another language is rather complicated, primarily because of their huge size and heavy use of FORTRAN mathematical libraries. But some intrinsic accelerator concepts, such as nested structure of modern accelerators, look very pretty when implemented with the object-oriented approach. In this paper we present the object-oriented version of ZLIB, numerical library for differential algebra and show how the modern approaches can simplify the development and support of accelerator codes, decrease code size, and allow description of complex mathematical transformations by simple language.
Date:
January 1, 1994
Creator:
Malitsky, N.; Reshetov, A. & Yan, Y.
Object Type:
Report
System:
The UNT Digital Library
Zonal Flow Measurements Concept I
We study the characteristics of self-generated zonal flows as observed in nonlinear global gyrokinetic simulations of toroidal ITG turbulence for typical parameters of DIII-D core plasmas, and discuss various possibilities for experimental measurements and the development of new diagnostics.
Date:
October 1, 1999
Creator:
Synakowski, E.J.; Burrell, K.H.; Nazikian, R.; Hahm, T.S. & Lin, Z.
Object Type:
Report
System:
The UNT Digital Library
Zonal statistics in (general circulation model) GCM/GCM/Data intercomparisons
Comparisons of general circulation model (GCM) results with each other and with climate data are routinely made on a variety of spatial scales. In bridging the gap from larger scale behavior (global, hemispheric) to the regional, zonal statistics are commonly used. Here, statistics are developed using values at all longitudinal gridpoints at a specified latitude and these are displayed as a function of latitude. The zonal average is the most routinely used of these statistics, but there are many other statistics available, few of which are ever examined. These provide a rich array of diagnostic measures for intercomparing models with each other and with observational data. Several of these measures are explored here: (1) histograms or boxplots displaying the detailed distributions, (2) rms or average absolute pointwise differences between model and data sets and (3) cross correlations and auto correlations. 5 figs.
Date:
November 1, 1990
Creator:
Grotch, S.L.
Object Type:
Article
System:
The UNT Digital Library
Zone conditioning in a California foothill house
The principal focus of the reported research is the performance of the installed zoned air distribution system in a house located in the foothills northeast of Sacramento California. The 297 m{sup 2} two story house contained a central air conditioner and an air distribution system with four dampered supply duct legs. The air conditioning system included a two speed fan and two speed compressor, with the air handler placed inside a closet and almost all the ducts located inside the building envelope. The uninsulated sheet metal ducts ran inside a space between stories and in interior walls. The performance parameters examined included: (1) duct leakage, (2) duct conduction, (3) zoning performance and (4) equipment efficiency impacts. In conclusion, two major points were made concerning the test house. The first was that substantial energy benefits were obtained by placing the ducts inside the conditioned space. The second was that the energy benefits from zoning the house were not realized, primarily due to thermal stratification and the open floor plan in the house. Secondary impacts lowering zoning performance were the k& of return duct dampers and leakage and conduction losses in the air distribution system. Utility programs or building standards promoting zoning …
Date:
December 1, 1993
Creator:
Jump, D. & Modera, M.
Object Type:
Report
System:
The UNT Digital Library
Zone of capture analysis for the A/M area of the Savannah River Site
The groundwater of the A/M Area of the Savannah River Site (SRS) is contaminated with trichloroethylene (TCE) and perchloroethylene (PCE) as the result of the past use and disposal of these solvents. For the purpose of remediating this contamination, the A/M Area of the SRS has been divided into three sectors termed the central, northern (or SRL), and southern sectors. The central portion of the A/M Area has had an active remediation system of eleven recovery wells since 1985 and its effectiveness has been evaluated through groundwater modeling. Remediation will soon begin at the northern or SRL sector with a pump and treat system of six wells distributed at four different locations with total pumping of approximately 250 gallons per minute (gpm). The locations and effectiveness of the capture system for each sector has been estimated through groundwater modeling without full consideration of the central recovery system. This report will provide an estimate of the number of recovery wells required for the southern sector and also consider the effects of the current and planned recovery systems for the northern and central plumes. The southern sector contamination (which is defined as the area south of the M-Area basin) has been initially …
Date:
December 1, 1991
Creator:
Haselow, J. S.; Beaudoin, C. M. & Schreuder, P. J.
Object Type:
Report
System:
The UNT Digital Library
Zone Refining of Plutonium Metal
The zone refining process was applied to Pu metal containing known amounts of impurities. Rod specimens of plutonium metal were melted into and contained in tantalum boats, each of which was passed horizontally through a three-turn, high-frequency coil in such a manner as to cause a narrow molten zone to pass through the Pu metal rod 10 times. The impurity elements Co, Cr, Fe, Ni, Np, U were found to move in the same direction as the molten zone as predicted by binary phase diagrams. The elements Al, Am, and Ga moved in the opposite direction of the molten zone as predicted by binary phase diagrams. As the impurity alloy was zone refined, {delta}-phase plutonium metal crystals were produced. The first few zone refining passes were more effective than each later pass because an oxide layer formed on the rod surface. There was no clear evidence of better impurity movement at the slower zone refining speed. Also, constant or variable coil power appeared to have no effect on impurity movement during a single run (10 passes). This experiment was the first step to developing a zone refining process for plutonium metal.
Date:
August 1, 1994
Creator:
Blau, M. S.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Zone refining of plutonium metal
The purpose of this study was to investigate zone refining techniques for the purification of plutonium metal. The redistribution of 10 impurity elements from zone melting was examined. Four tantalum boats were loaded with plutonium impurity alloy, placed in a vacuum furnace, heated to 700{degrees}C, and held at temperature for one hour. Ten passes were made with each boat. Metallographic and chemical analyses performed on the plutonium rods showed that, after 10 passes, moderate movement of certain elements were achieved. Molten zone speeds of 1 or 2 inches per hour had no effect on impurity element movement. Likewise, the application of constant or variable power had no effect on impurity movement. The study implies that development of a zone refining process to purify plutonium is feasible. Development of a process will be hampered by two factors: (1) the effect on impurity element redistribution of the oxide layer formed on the exposed surface of the material is not understood, and (2) the tantalum container material is not inert in the presence of plutonium. Cold boat studies are planned, with higher temperature and vacuum levels, to determine the effect on these factors. 5 refs., 1 tab., 5 figs.
Date:
May 1, 1997
Creator:
unknown
Object Type:
Article
System:
The UNT Digital Library
Zone refining of sintered, microwave-derived YBCO superconductors
Post-sintering treatments such as zone melting under thermal gradient has been conducted on sintered YBCO tape cast films. YBCO precursor powder was derived through decomposition of a mixture of nitrates of cations in a microwave oven for {approx}4 min. The resulting powder was characterized and made into thin sheets by tape casting and then sintered at 945 C for 5 h. The sintered tapes were subjected to repeated zone refining operations at relatively high speeds of {approx}30 mm/h. A microstructure having uniformly oriented grains in the a-b plane throughout the bulk of the sample was obtained by three repeated zone refining operations. Details of precursor preparation, microwave processing and its advantages, zone refining conditions, and microstructural features are presented in this paper.
Date:
July 1, 1993
Creator:
Warrier, K. G. K.; Varma, H. K.; Mani, T. V.; Damodaran, A. D. & Balachandran, U.
Object Type:
Report
System:
The UNT Digital Library
Zone sintering of ceramic fuels
Cold pressed UC{sup 2} fuel compacts are sintered at temperatures greater than about 1850 C while in contract with a sintering facilitator material, e.g., tantalum, niobium, tungsten or a metal carbide such as uranium carbide, thereby allowing for a reduction in the overall porosity and leaving the desired product, i.e., a highly dense, large-grained uranium dicarbide. The process of using the sintering facilitator materials can be applied in the preparation of other carbide materials.
Date:
December 31, 1991
Creator:
Matthews, R. Bruce; Chidester, Kenneth M. & Moore, H. Gene
Object Type:
Patent
System:
The UNT Digital Library
Zoning's Contribution to Residential Property Value
Technical report that describes how zoning may affect the prices of homes in College Station, Texas.
Date:
February 1990
Creator:
Harris, Jack C.
Object Type:
Report
System:
The Portal to Texas History
The ZOOM Fermilab physics class libraries
Several years ago, the two major collider experiments at Fermilab (D#31; and CDF) decided that new software development for Run II will be largely done in C++. The run is slated to start in 1.5 years, an aggressive time frame for a major change in development language and style. If despite the transition each experiment (and sometimes multiple groups within an experiment) were to develop each needed mod- ule, the C++ strategy would not be advantageous. Thus it was deemed useful to have a library development group speci#12;cally responsive to Run II needs. This Fer- milab Physics Class Library Task Force (ZOOM) would also expand the core of C++ expertise available for Fermilab physicists to draw upon. C++ di#11;ers from Fortran in that the for common use of routines and libraries is greater. But this potential is not realized automatically. Unless coordina- tion issues are considered from the start, utilities produced by one group generally do mot meet the needs of other groups|and each group ends up creating independant software. To help increase code sharing, the centralized ZOOM task force must: Actively pursue outside (commercial and free-ware) packages. If ZOOM can verify that package X meets some needs in a …
Date:
November 1, 1998
Creator:
Mark Fischler, Walter Brown, Philippe Canal and John Marraffino
Object Type:
Article
System:
The UNT Digital Library
A zooming Web browser
We are developing a prototype zooming World-Wide Web browser within Pad++, a multiscale graphical environment. Instead of having a single page visible at a time, multiple pages and the links between them are depicted on a large zoomable information surface. Pages are scaled so that the page in focus is clearly readable with connected pages shown at smaller scales to provide context. We quantitatively compared performance with the Pad++ Web browser and Netscape in several different scenarios. We examined how quickly users could answer questions about a specific Web site designed for this test. Initially we found that subjects answered questions slightly slower with Pad++ than with Netscape. After analyzing the results of this study, we implemented several changes to the Pad++ Web browser, and repeated one Pad++ condition. After improvements were made to the Pad++ browser, subjects using Pad++ answered questions 23% faster than those using Netscape.
Date:
December 31, 1996
Creator:
Bederson, Benjamin B.; Hollan, James D.; Stewart, Jason; Rogers, David; Vick, David; Ring, Laura et al.
Object Type:
Article
System:
The UNT Digital Library
Zooplankton data: Vertical distributions of zooplankton in the Norweigian and Greenland Seas during summer, 1989
Recent studies of zooplankton populations in the Greenland Sea have focused on processes at the Marginal Ice Zone (MIZ) and the areas immediately adjacent to it under the ice and in open water. These studies have shown a relatively short period of intense secondary productivity which is closely linked temporally and spatially to phytoplankton blooms occurring near the ice edge in spring and early summer. During the summer of 1989 we participated in a project focusing on benthic and water column processes in the basins of the Norwegian and Greenland Seas. This study allowed us to compare biological processes at the MIZ with those occurring in the open waters of the Greenland Sea, and to compare processes at both of these locations with those in the Norwegian Sea. The data presented in this report are the results of zooplankton net tows covering the upper 1000 meters of the water column over the Norwegian Sea basin and the Greenland Sea basin, and the upper 500 meters of open water adjacent to the MIZ in the Greenland Sea. Sampling was conducted between 12 and 29 July 1989.
Date:
August 1, 1993
Creator:
Lane, P. V. Z.; Smith, S. L. & Schwarting, E. M.
Object Type:
Report
System:
The UNT Digital Library
Zr and Mo isotopes in single presolar graphite grains : a record of stellar nucleosynthesis.
Thirty-two individual graphite grains from the Murchison meteorite were analyzed for their Mo and/or Zr isotopic compositions by laser ablation resonant ionization mass spectrometry. {sup 96}Zr/{sup 94}Zr ratios range from 0.074 times to 10 times the solar value. Five grains have depletions in {sup 96}Zr, suggestive of the s-process, and two grains have extraordinary enrichments in {sup 96}Zr, suggestive of the r-process. Most graphite grains have close-to-terrestrial Mo isotopic imposition, but five have s-process Mo nucleosynthesis signatures.
Date:
February 10, 1998
Creator:
Nicolussi, G. K.
Object Type:
Article
System:
The UNT Digital Library
ZrO sub 2 and ZrO sub 2 /SiC particle reinforced-MoSi sub 2 matrix composites
ZrO{sub 2}-MoSi{sub 2} and ZrO{sub 2}/SiC-MoSi{sub 2} composites were fabricated by hot pressing and hot pressing/HIP at 1700{degrees}C. No reactions between ZrO{sub 2}, SiC, and MoSi{sub 2} were observed. An amorphous silica glassy phase was present in all composites. Composites with unstabilized ZrO{sub 2} particles exhibited the highest room temperature fracture toughness, reaching a level three times that of pure MoSi{sub 2}. Both the room temperature toughness and 1200{degrees}C strength of ZrO/{sub 2}SiC-MoSi{sub 2} composites were higher than ZrO{sub 2}-MoSi{sub 2} composites, indicating beneficial effects of combined reinforcement phases. Low strength levels were observed at 1400{degrees}C due to the presence of the silica glassy phase. Elimination of glassy phases and refinements in microstructural homogeneity are processing routes important to the optimization of the mechanical properties of these types of composites. 18 refs., 7 figs.
Date:
January 1, 1991
Creator:
Petrovic, J. J.; Bhattacharya, A. K.; Honnell, R. E.; Mitchell, T. E. (Los Alamos National Lab., NM (United States)); Wade, R. K. (Arizona Materials Lab., Tucson, AZ (United States)) & McCellan, K. J. (Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science and Engineering)
Object Type:
Article
System:
The UNT Digital Library