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Gamma-spectrometry with Compton suppressed detectors arrays

Description: Recent results of experiments performed with two different Compton-suppressed detectors arrays in Daresbury and Berkeley (/sup 163,164/Yb and /sup 154/Er, respectively), are presented together with a brief description of the national French array presently under construction in Strasbourg. 25 refs., 15 figs.
Date: January 1, 1985
Creator: Schueck, C.; Hannachi, F.; Chapman, R.; Lisle, J.C.; Mo, J.N.; Paul, E. et al.
Partner: UNT Libraries Government Documents Department

Processes for the control of /sup 14/CO/sub 2/ during reprocessing

Description: The fixation of /sup 14/CO/sub 2/ may be required at some future time because of the significant fractional contribution of /sup 14/C, via the ingestion pathway, to the total population dose from the nuclear fuel cycle, even though the actual quantity of this dose is very small when compared to natural background. The work described here was done in support of fuel reprocessing development, of both graphite fuel (HTGRs) and metal-clad fuel (LWRs and LMFBRs), and was directed to the control of /sup 14/CO/sub 2/ released during reprocessing operations. However, portions of this work are also applicable to the control of /sup 14/CO/sub 2/ released during reactor operation. The work described falls in three major areas: (1) The application of liquid-slurry fixation with Ca(OH)/sub 2/, which converts the CO/sub 2/ to CaCO/sub 3/, carried out after treatment of the CO/sub 2/-containing stream to remove other gaseous radioactive components, mainly /sup 85/Kr. This approach is primarily for application to HTGR fuel reprocessing. (2) The above process for CO/sub 2/ fixation, but used ahead of Kr removal, and followed by a molecular sieve process to take out the /sup 85/Kr. This approach was developed for use with HTGR reprocessing, but certain aspects also have application to metal-clad fuel reprocessing and to reactor operation. (3) The use of solid Ba(OH)/sub 2/ hydrate reacting directly with the gaseous phase. This process is generally applicable to both reprocessing and to reactor operation.
Date: January 1, 1980
Creator: Notz, K.J.; Holladay, D.W.; Forsberg, C.W. & Haag, G.L.
Partner: UNT Libraries Government Documents Department

Studies of the dissolution of geothermal scale

Description: Samples of geothermal scale formed from Magmamax No. 1 and Woolsey No. 1 wells in the Imperial Valley, Calif., were exposed to concentrated and dilute solutions of common laboratory reagents. The time of exposure and temperature of the reagent were also varied. Several reagents easily dissolved significant amounts of the scale. An in situ test was performed with marginal success.
Date: February 4, 1980
Creator: Deutscher, S.B.; Ross, D.M.; Quong, R. & Harrar, J.E.
Partner: UNT Libraries Government Documents Department

Application of the carbon dioxide-barium hydroxide hydrate gas-solid reaction for the treatment of dilute carbon dioxide-bearing gas streams

Description: The removal of trace components from gas streams via irreversible gas-solid reactions in an area of interest to the chemical engineering profession. This research effort addresses the use of fixed beds of Ba(OH)/sub 2/ hydrate flakes for the removal of an acid gas, CO/sub 2/, from air that contains approx. 330 ppM/sub v/ CO/sub 2/. Areas of investigation encompassed: (1) an extensive literature review of Ba(OH)/sub 2/ hydrate chemistry, (2) microscale studies on 0.150-g samples to develop a better understanding of the reaction, (3) process studies at the macroscale level with 10.2-cm-ID fixed-bed reactors, and (4) the development of a model for predicting fixed-bed performance. Experimental studies indicated fixed beds of commercial Ba(OH)/sub 2/.8H/sub 2/O flakes at ambient temperatures to be capable of high CO/sub 2/-removal efficiencies (effluent concentrations <100 ppB), high reactant utilization (>99%), and an acceptable pressure drop (1.8 kPa/m at a superficial gas velocity of 13 cm/s). Ba(OH)/sub 2/.8H/sub 2/O was determined to be more reactive toward CO/sub 2/ than either Ba(OH)/sub 2/.3H/sub 2/O or Ba(OH)/sub 2/.1H/sub 2/O. A key variable in the development of this fixed-bed process was relative humidity. Operation at conditions with effluent relative humidities >60% resulted in significant recrystallization and restructuring of the flake and subsequent pressure-drop problems.
Date: September 1, 1983
Creator: Haag, G.L.
Partner: UNT Libraries Government Documents Department

Geochemical modeling research related to the surface disposal of processed oil shale solid waste. [Elements and compounds in oil shale wastes]

Description: Several geochemical codes are available in the literature to model chemical processes such as oxidation-reduction, precipitation-dissolution, formation of solution complex, adsorption, and ion exchange. However, these models differ in the environments to which they apply. The objective of this research was to evaluate the applicability of existing geochemical codes to predict water quality from an oil shale solid waste environment. We selected EQ3/EQ6, GEOCHEM, MINTEQ, PHREEQE, SOLMNEQ, and WATEQFC geochemical models for further evaluation. We concluded that all these models lack thermodynamic data for minerals and solution complexes which are important for oil shale solid waste studies. Selection of any one of the models would require development of a more reliable thermodynamic database, and this report describes the initiation of that work. So far, critical evaluation of thermodynamic data has been completed for Sr, F, Mo, and Se. 64 refs., 15 tabs.
Date: October 1, 1987
Creator: Reddy, K. J. & Drever, J. I.
Partner: UNT Libraries Government Documents Department

The EPRI Laboratory experiments at ANL. [Vaporization of core-concrete mixtures]

Description: The vaporization of core-concrete mixtures is being measured using a transpiration method. Mixtures of stainless steel, concrete (limestone or basaltic) and urania (doped with La/sub 2/O/sub 3/, SrO, BaO, and ZrO/sub 2/) are vaporized at 2150 - 2400 K from a zirconia crucible into flowing He - 6% H/sub 2/ gas. Up to 600 ppM H/sub 2/O is added to the gas to fix the partial molar free energy of oxygen in the range -420 kJ to -550 kJ. The fraction of the sample that is vaporized is determined by weight change and by chemical analyses on the condensates that are collected in an Mo condenser tube. The results are being used to test the thermodynemic data base and the underlying assumptions of computer codes used for prediction of release during the severe accident. 13 refs., 2 tabs.
Date: October 28, 1987
Creator: Roche, M.F.; Settle, J.L.; Leibowitz, L.; Johnson, C.E. & Ritzman, R.L.
Partner: UNT Libraries Government Documents Department

Comparison of detector materials for time-of-flight positron tomography

Description: Knowledge of detection efficiency and timing resolution is essential when comparing detector materials for time-of-flight positron tomography. We present results of Monte Carlo calculations of the detection efficiency of plastic, lead loaded plastic, NaI(T1), liquid xenon, bismuth germanate (BGO), CsF, BaF/sub 2/, Ge, and HgI/sub 2/ for 511 keV photons. We also use recently published values of timing resolution for these detector materials to tabulate the quantity (efficiency)/sup 2//(time resolution) which is a measure of the relative sensitivity for time of flight positron tomography.
Date: June 1, 1982
Creator: Derenzo, S.E.
Partner: UNT Libraries Government Documents Department

Preparation and some properties of H/sub x/REBa/sub 2/Cu/sub 3/O/sub 7/ (RE = Er, Nd, Dy, Ho, Gd) superconductors

Description: Hydrogen gas has been found to react directly with the subject oxides. Most exhibit a small region of H solid solubility which remains superconducting with a slight increase in critical temperature (1 to 2K). At higher H contents a hydrogen rich hydride phase precipitates which is amorphous. The H rich phases are not superconducting at 4K or above. Neutron diffraction studies of D/sub 1.55/YBa/sub 2/Cu/sub 3/O/sub 7/ confirm that the D rich phase is amorphous but that its precipitation causes increased microtwinning in the D saturated oxide. 12 refs., 3 figs.
Date: January 1, 1988
Creator: Johnson, J.; Suenaga, M.; Thompson, P. & Reilly, J.
Partner: UNT Libraries Government Documents Department

Study of high [Tc] superconducting thin films grown by MOCVD

Description: Work is described briefly, which was carried out on development of techniques to grow metal-semiconductor superlattices (artificially layered materials) and on the copper oxide based susperconductors (naturally layered materials). The current growth technique utilized is metalorganic chemical vapor deposition (MOCVD). CdTe, PbTe, La, LaTe, and Bi[sub 2]Te[sub 3] were deposited, mostly on GaAs. Several YBa[sub 2]Cu[sub 3]O[sub 7] compounds were obtained with possible superconductivity at temperatures up to 550 K (1 part in 10[sup 4]). YBa[sub 2]Cu[sub 3]O[sub 7[minus]x] and Tl[sub 2]CaBa[sub 2]Cu[sub 2]O[sub y] thin films were deposited by MOCVD on common substrates such as glass.
Date: January 1, 1990
Creator: Erbil, A.
Partner: UNT Libraries Government Documents Department

Direct conversion of methane to C sub 2 's and liquid fuels

Description: Research on promoted metal oxide catalysts has continued with the study of alkaline earth/metal oxide halide catalysts. A barium bromide/alumina catalyst was comparable in methane conversion and selectivity to C{sub 2}'s to barium chloride/alumina catalysts. The effects of varying methane to oxygen feed ratios were explored for one of the best alkaline earth catalysts and one of the best literature catalysts (Li/MgO). A significant decrease in the selectivity to C{sub 2}'s is observed upon addition of ethane to the feed gas (feed gas methane/ethane ratio of 3). This observation demonstrates that a significant amount of ethane should not be recycled during methane oxidation over these types of catalysts under process conditions used. Methane oxidation over barium carbonate alone results in high enough selectivities and methane conversions to suggest an oxidized barium species may be responsible for methane oxidation on barium/metal oxide catalysts. Methane coupling studies have continued using layered perovskite catalysts in the cofeed mode and double perovskite catalysts in the sequential mode. Addition of sodium to the double perovskite LaCaMnCoO{sub 6} resulted in a catalyst with improved selectivity over the one without sodium. A reactor system containing two reactors in under construction. These reactors will be used to study different feed diluents, including steam. One reactor will be used to study the effects of pressure on the reaction. Process economics were explored for a hypothetical methane coupling scheme employing a feed mixture of 7/2/1 nitrogen/methane/oxygen. Economic evaluations of the first two of a series of cases based on extrapolations of Union Carbide methane coupling results have been completed. 33 refs., 17 figs., 2 tabs.
Date: February 14, 1990
Creator: Warren, B.K.; Campbell, K.D. & Matherne, J.L.
Partner: UNT Libraries Government Documents Department

Use of ceramic materials in waste-package systems for geologic disposal of nuclear wastes

Description: A study to investigate the potential use of ceramic materials as components in the waste package systems was conducted. The initial objective of the study was to screen and compare a large number of ceramic materials and identify the best materials for the proposed application. The principal method used to screen the candidates was to subject samples of each material to a series of leaching tests and to determine their relative resistance to attack by the leach solutions. A total of 14 ceramic materials, plus graphite and basalt were evaluated using three different leach solutions: demineralized water, a synthetic Hanford ground water, and a synthetic WIPP brine solution. The ceramic materials screened were Al/sub 2/O/sub 3/ (99%), Al/sub 2/O/sub 3/ (99.8%), mullite (2Al/sub 2/O/sub 3/.SiO/sub 2/), vitreous silica (SiO/sub 2/), BaTiO/sub 3/, CaTiO/sub 3/, CaTiSiO/sub 5/, TiO/sub 2/, ZrO/sub 2/, ZrSiO/sub 4/, Pyroceram 9617, and Marcor Code 9658 machinable glass-ceramic. Average leach rates for the materials tested were determined from analyses of the leach solutions and/or sample weight loss measurements. Because of the limited scope of the present study, evaluation of the specimens was limited to ceramographic examination. Based on an overall evaluation of the leach rate data, five of the materials tested, namely graphite, TiO/sub 2/, ZrO/sub 2/, and the two grades of alumina, exhibited much greater resistance to leaching than did the other materials tested. Based on all the experimental data obtained, and considering other factors such as cost, availability, fabrication technology, and mechanical and physical properties, graphite and alumina are the preferred candidates for the barrier application. The secondary choices are TiO/sub 2/ and ZrO/sub 2/.
Date: December 1, 1980
Creator: Fullam, H.T.
Partner: UNT Libraries Government Documents Department

Evaluation of ceramic and polymeric materials for use in engineered barrier systems

Description: Ceramic materials evaluated in the screening studies were Al/sub 2/O/sub 3/ (99.8%), mullite, vitreous silica, BaTiO/sub 3/, CaTiO/sub 3/, CaZrO/sub 3/, CaTiSiO/sub 5/, TiO/sub 2/, ZrSiO/sub 4/, basalt, Pyroceram 9617, and Marcor code 9658 machinable glass ceramic. One grade of graphite (Toyotanso IB-11) was also evaluated. Demineralized water, a synthetic Hanford groundwater, and a synthetic NaCl brine solution were used in the screening tests. Demineralized water was used in all five of the leach tests, but the other solutions were only used in the static leach tests at 150 and 250/sup 0/C. Based on the results obtained, graphite appears to be the most leach resistant of the materials tested with the two grades of alumina being the best of the ceramic materials. Titanium dioxide and ZrO/sub 2/ are the most leach resistant of the remaining materials. Candidate materials from all three general classes of polymers (thermoplastics, thermosets, and elastomers) were considered in the selection of materials. Selected groups of polymers were tested in the flowing autoclave at 150, 200, and 250/sup 0/C with some polymers being further tested at the next higher temperature. Next, selected samples were exposed to gamma radiation. These samples were then submitted for tensile and elongation measurements. Selected samples which appeared promising from both autoclave and radiation testing were further evaluated by impact tests. The materials that appeared most promising after autoclave testing were the EPDM rubbers, polyphenylene sulfide, poly(ethylene-tetrafluoroethylene) copolymer, and polyfurfuryl alcohol. The radiation dose had little effect on polyfurfuryl alcohol and polyphenylene sulfide samples; very significant decreases in elongation were observed for the fluorocarbon copolymer and the EPDM rubbers. While the polyphenylene sulfide and polyfurfuryl alcohol showed little change in impact strength, poly(ethylene-tetrafluoroethylene) decreased in impact strength.
Date: January 1, 1980
Creator: Fullam, H.T. & Skiens, W.E.
Partner: UNT Libraries Government Documents Department

Actinide removal from aqueous solution with activated magnetite

Description: An actinide aqueous waste treatment process using activated magnetite has been developed at Rocky Flats. The use and effectiveness of various magnetites in lowering actinide concentrations in aqueous solution are described. Experiments indicate that magnetite particle size and pretreatment (activation of the magnetite surface with hydroxyl ions greatly influence the effective use of magnetite as an actinide adsorbent. With respect to actinide removal, Ba(OH)/sub 2/-activated magnetite was more effective over a broader pH range than was NaOH-activated magnetite. About 50% less Ba(OH)/sub 2/-activated magnetite was required to lower plutonium concentration from 10/sup -4/ to 10/sup -8/ g/l. 7 refs., 8 tabs.
Date: August 10, 1987
Creator: Kochen, R.L. & Thomas, R.L. (ed.)
Partner: UNT Libraries Government Documents Department

Chemical aspects of nuclear waste treatment

Description: The chemical aspects of the treatment of gaseous, liquid, and solid wastes are discussed in overview. The role of chemistry and the chemical reactions in waste treatment are emphasized. Waste treatment methods encompass the chemistry of radioactive elements from every group of the periodic table. In most streams, the radioactive elements are present in relatively low concentrations and are often associated with moderately large amounts of process reagents, or materials. In general, it is desirable that waste treatment methods are based on chemistry that is selective for the concentration of radionuclides and does not require the addition of reagents that contribute significantly to the volume of the treated waste. Solvent extraction, ion exchange, and sorbent chemistry play a major role in waste treatment because of the high selectivity provided for many radionuclides. This paper deals with the chemistry of the onsite treatment methods that is typically used at nuclear installations and is not concerned with the chemistry of the various alternative materials proposed for long-term storage of nuclear wastes. The chemical aspects are discussed from a generic point of view in which the chemistry of important radionuclides is emphasized.
Date: January 1, 1980
Creator: Bond, W.D.
Partner: UNT Libraries Government Documents Department