bluuebunny/crossref_metadata_2025_split huggingface dataset:
Backfill-Waste Interactions in Repository Simulating Tests
Authors: Sasaki Noriaki , Komarneni Sridhar , Scheetz Barry E. , Roy Rustum 
Published: March 2011

ABSTRACTCandidate backfill materials such as montmorillonite and clinoptilolite with and without the presence of simulated nuclear waste solids such as borosilicate glass, glass ceramic, sintered ceramic and supercalcine ceramic were investigated under repository simulating conditions (=300°C and 30 MPa). Experiments were conducted under semi-wet as well as wet repository conditions.Montmorillonite and clinoptilolite did not seem to alter under both semi-wet and wet repository conditions as determined by XRD. However, the above backfill materials reacted extensively with wastes under both conditions. They altered to feldspar (oligoclase) in the presence of borosilicate glass and to analcime in the presence of particular ceramics under both semi-wet and wet repository conditions. Alteration of montmorillonite could not be detected either in the presence of the glass ceramic or supercalcine ceramic under both repository conditions. However, clinoptilolite altered to analcime in the presence of glass ceramic or supercalcine ceramic under wet repository conditions. Reactions of backfill materials with simulated wastes immobilized waste elements such as Cs, Mo, etc., by forming new phases such as analcime, oligoclase and powellite. In fact, analyses of product solutions from interaction runs indicated that the presence of backfill materials during the alteration of waste solids served to drastically reduce the concentration of some radionuclides in solutions. These results suggest that properly selected backfills can provide the simplest and most effective chemical (or thermodynamic) engineered barrier in an intelligently designed multibarrier system. Moreover, they indicate that the μ, P, and T in the usual leach tests (e.g. Paige, IAEA, etc.) are such that results of such tests cannot have any value in evaluating waste form behavior under repository conditions.
Iron-Enriched Basalt and its Application to Three-Mile Island Radioactive Waste Disposal
Authors: Kelsey P. V. , Schuman R. P. , Welch J. M. , Owen D. E. , Flinn J. E. 
Published: March 2011

ABSTRACTDemonstration tests were performed on iron-enriched basalt (IEB), a dissolution and immobilization medium for TMI radioactive wastes. Zeolite of the type used for cesium and strontium decontamination of TMI containment water was mixed with 20 wt% additives and melted at 1500°C to form IEB. Cesium volatility from the IEB melts was low. Leaching tests in 90°C deionized water showed leach rates of 6 μg/cm2 d for both cesium and strontium. IEB melts were used to dissolve Type 304 SS pellets and UO2 pellets clad with zircaloy in order to simulate immobilization of TMI core debris. Bubbling air through the melts greatly enhanced the dissolution of these components.
Migration of Radionuclide Chains In Subseabed Disposal
Authors: Ray A. K. , Nuttall H. E. 
Published: March 2011

ABSTRACTIn this study of subseabed disposal, the two dimensional (axial and radial) migration of radionuclide chains released from a canister located in a sedimentary layer bounded at the top by the ocean and at the bottom by an impermeable basalt zone is analyzed to determine the escape rate of radlonuclides into the seawater. Analytical solutions have been derived to represent the transient concentration profiles within the sediment, flux and discharge rates to the water column of each member present in a decay chain. Using the properties of chain members present in actinide decay systems, the effects of half-life, adsorption equilibrium and other relevant parameters are elucidated.
Formulation and Processing of Polyphase Ceramics for High Level Nuclear Waste
Authors: Harker Alan B. , Morgan Peter E. D. , Clarke David R. , Flintoff John F. 
Published: March 2011

ABSTRACTTwo basic crystalline phase assemblages have been developed for incorporating the full range of Savannah River Plant waste compositions into polyphase ceramic forms. Both phase assemblages provide crystalline host phases, with stable mineral analogues, for all radionuclides in the waste. The first, an alumina based assemblage, immobilizes the radioactive elements in solid solutions of magnetoplumbite and uraninite with the bulk non-radioactive waste elements being present in spinel and nepheline. The second assemblage uses the titanate based “zirconolite” type fluorite structure and the alumina/iron based magnetoplumbite phases to host the radioactive nuclei with spinel and nepheline, again providing crystalline hosts for the non-radioactive elements. Both phase assemblages can be consolidated to a fine grain ceramic by hot isostatic pressing at 1040°C pressures from 20,000 to 30,000 psi. Redox control during processing, just sufficient to reduce uranium to the tetravalent state, is used.
On-Line Measurements of the Volatilization of Ruthenium in a Vitrification Process
Authors: Odoj R. , Schwitz M. 
Published: March 2011

ABSTRACTThe studies were performed using Ru–103 as a tracer. The volatilization of Ru from ruthenium containing liquids, like HAW-solutions, is about 15%. A chemical denitration of these solutions with HCHO or HCOOH reduces the volatilization to about 2%. Additional catalytic reduction with Fe-powder lowers the volatilization to about 4 ‰. The carry over of Ru seems to depend on the aerosol production rate and not the vapor pressure. Only RuO2 could be detected in the off-gas.
Behavior of Radionuclides During the Smelting of Noncombustible Solid Wastes
Authors: Osaki Makoto , Yokoi Shinji , Miyagawa Minoru 
Published: March 2011

ABSTRACTThe melting process of noncombustible solid wastes seems to be one of the most promising processes for volume reduction and immobilization. This melting process needs a high temperature of around 1500° C, but the behavior of radionuclides in such a process and at such a temperature has not been fully examined. We melted small contaminated samples to examine the behavior of radionuclides. Melted products were subjected to leaching tests.Many assorted samples were melted, and we found that the vapour pressure of the radionuclide determined the distribution between melted products and dusts. The standard free energy of oxide formation and the quantity of stable nuclide of the radionuclide determined the distribution between metal and slag products. The leaching rate of melted products was sufficiently low.
Vitrification of High-Level Radioactive Waste in a Small-Scale Joule-Heated Ceramic Melter
Authors: Woolsey Gerald B. , John Plodinec M. 
Published: March 2011

ABSTRACTVitrification is the reference process for the immobilization of radioactive waste from the production of defense materials at the Savannah River Plant (SRP). Since 1979, a small vitrification facility (1 Ib/hr) has been operated at the Savannah River Laboratory using actual SRP waste. In previous studies. dried waste was fed to this smaller melter. This report discusses direct feeding of actual liquid-waste slurries to the small melter. These liquidfeeding tests demonstrated that addition of premelted glass frit to the waste slurry reduces the amount of material volatilized. Results of these tests are in accord with results of large-scale tests with actual waste.
Metastable Liquid Immiscibility in Nuclear-Waste-Glasses
Authors: Engell John E. , Roed GjerlØff 
Published: March 2011

ABSTRACTFor glass systems related to two potential nuclear-wasteglasses, ABS–39 and ABS–41, the 600°C isotherm of the metastable immiscibility field has been located experimentally. Both glasses are in the one phase glass field down to temperatures below 600°C. ABS–39 and ABS–41 are Na2O-B2O3-SiO2 glasses containing 1.66 wt% UO2 and 9 wt% of simulated fission products. Additional components in ABS–39 are Al2O3 and Fe2O3. In ABS–41 these two oxides are partly substituted with ZnO and Li2O. This substitution causes an extension of the metastable immiscibility field relative to the ABS–39 system.
Interim Waste Forms for High-Level Radioactive Wastes: Processing and Properties
Authors: Bandyopadhyay G. 
Published: March 2011

ABSTRACTSeveral simulated interim waste forms have been investigated in the laboratory to study their suitability for application in handling and transportation of high-level radioactive wastes to terminal processing sites. In the fused-salt/sludge option, the neutralized supernatant liquid and the precipitated sludge are treated simultaneously to form fused-salt cakes. Silicate-based options, in which sodium silicate or sodium silicate and Ca(OH)2 act as binders for the sludge, require prior separation of the sludge and the soluble radioactive constituents from the supernatant before the waste form can be prepared. The results from tests on simulated fused-salt waste forms indicated that the process simplicity of this option is partially offset by the high water solubility and hygroscopicity of the product, which would necessitate special precautions during transportation and storage. The most promising silicate-based option is the ambienttemperature silicate sludge process, in which the sludge is mixed with sodium silicate [and sometimes with Ca(OH)2] and subsequently exposed to a contrelled-humidity environment at room temperature to form a chemical bond. Solid material containing 75 wt % synthetic calcined sludge, prepared by this process, has sufficient physical, chemical, and mechanical stability for use as an interim waste form.
Effects of Alpha, Gamma, and Alpha-Recoil Radiation on Borosilicate Glass Containing Savannah River Plant Defense High-Level Nuclear Waste
Authors: Bibler Ned E. 
Published: March 2011

ABSTRACTAt the Savannah River Plant, the reference process for the immobilization of defense high-level waste (DHLW) for geologic storage is vitrification into borosilicate glass. During geologic storage for 106y, the glass would be exposed to ∼3 × 1010 rad of β radiation, ∼1010 rad of γ radiation, and 1018 particles/g glass for both α and α-recoil radiation. This paper discusses tests of the effect of these radiations on the leachability and density of the glass. No effect of the radiations was detected that reduced the effectiveness of the glass for long-term storage of DHLW even at doses corresponding to 106 years storage for the actual glass. For the tests, glass containing simulated DHLW was prepared from frit of the reference composition. Three methods were used to irradiate the glass: external irradiations with beams of ∼200 keV or Pb ions, internal irradiations with Cm–244 doped glass, and external irradiations with Co–60 γ rays. Results with both Xe and Pb ions indicate that a dose of 3 × 1013 ions/cm2 (simulating >106 years storage) does not significantly increase the leachability of the glass in deionized water. Tests with Cm–244 doped glass show no increase in leach rate in deionized water up to a dose of 1.3 × 1018 α and α-recoils/g glass. The density of the Cm–244 doped glass has decreased by 1% at a dose of 1018 particles/g glass. With γ-radiation, the density has changed by <0.05% at a dose of 8.5 × 1010 rad. Results of leach tests in deionized water and brine indicated that this very large dose of γ-radiation increased the leach rate by only 20%. Also, the leach rates are 3 to 4 times lower in brine.
Influence of Irradiation With Gamma - Quanta and Beam of Accelerated Electrons on the Sorption Parameters of Clay Minerals of the Montmorillonite Group
Authors: Spitsyn V. I. , Balukova B. D. , Savushkina M. K. 
Published: March 2011

ABSTRACTThe minerals belonging to the montmorillonite group were studied. Under irradiation werp air-dry minerals as well as those in solutions containing 90Sr, which gave us an opportunity to study the irradiation influence on the soprtion accumulation of radionuclides. The analysis of the diffractograms of irradiated and nonirradiated minerals shows that the structure of the minerals belonging to the montmorillonite group remains unchanged, while alumosilicate layers converge which results in a decrease in interplane distance.
The Influence of Gamma Irradiation on the Leaching Behavior of a Modified Synroc-B Ceramic Waste Form
Authors: Solomah A. G. 
Published: March 2011

ABSTRACTThe leaching behavior of a sintered Modified SYNROC-B ceramic waste form containing l0wt% simulated high level radioactive waste, under the influence of γ-irradiation, has been investigated. Similar leaching experiments have been carried out in the absence of γ-irradiation, and the leach rates of Ba and Cs are presented for comparison studies. Acid/Base formation has been monitored through pH measurements of the leachants. A decrease in pH is found with γ-irradiation due to radiolytic nitric acid generation. Higher initial leach rates with a more pronounced subsequent drop in the case of Ba and Cs were observed with γ-irradiation than without irradiation. The results of the study are presented and discussed.
Management of Radioactive Wastes in Europe (Ec) History, Philosophy and Plans for the Next Five Years
Authors: Orlowski S. , Simon R.A 
Published: March 2011

ABSTRACTSince its first R & D programme on radioactive waste management in 1973, the European Community has been contributing a steadily increasing share of the European research effort in this field. A major part of the programme is devoted to the investigation and evaluation of management concepts for high-level and TRU wastes from the backend of the fuel cycle. Risk analysis studies for the assessment of multi-barrier terminal isolation systems currently have high priority.
Radiation Induced Impurity Precipitation in Mgo
Authors: Clement S. , Hodgson E. R. 
Published: March 2011

AbstractIn MgO irradiated at high dose rates and high temperatures with 1.8 MeV electrons, a suppression of the Fe3+ optical absorption band at 290 nm is observed. This suppression, a function of both dose rate and temperature, is consistent with a reduction process induced by oxygen displacement damage. Both thermal and radiation enhanced diffusion are involved and lead to the formation of iron containing precipitates. Similar results have been obtained for Ni2+.
Electrical Properties and Defect Structures of CoO and MnO at High Defect Content
Authors: Sykora G.P. , Mason T.O. 
Published: March 2011

AbstractDefect studies at high defect content in transition metal monoxides allow for the conduction mechanisms to be established and the nature of defect interactions to be studied. Conductivity and thermopower results in p-type, highly defective MnO are reported and analyzed with a combination of point defects and clusters. A high pressure oxygen apparatus to achieve defect contents up to 5 percent in CoO has been designed and constructed.
Structure-Transport Relationships in Fast Ion Conducting Alkali Borate Glasses
Authors: Fusco F. A. , Tuller H. L. , Uhlmann D. R. 
Published: March 2011

AbstractThe effect of CaO substitutions (between 1 and 10% (CaO)2/Li2O) on the transport and physical properties of two fast ion conducting lithium borate glass systems (37.3 mol % Li20, 62.7 mol % Li2O3 and 50 mol % Li2O, 50 mol % Li2O, 50 mol % B2O3) are investigated. Measurements of electrical conductivity, density and glass transition temperature are reported. The influence of strain effects on carrier mobility is examined. Measurements of electrical conductivity and molar volume are extended to a K2O·2B2O3 glass and compared with existing data for corresponding lithium and sodium diborate glasses.
Electronic Barriers Produced at Zno Surfaces By Ion Implantation And Annealing
Authors: Sonder E. , Zuhr R. A. , Martinelli J. R. 
Published: March 2011

AbstractModern varistors are made of polycrystalline ZnO, doped to create Schottky-like barriers at the grain boundaries. To allow the study of tailored single barrier junctions, we have implanted ZnO crystals with Bi, Sb and transition metals. The electrical properties and the distribution of Bi and Sb were measured in the implanted crystals as a function of annealing temperature. After implantation and before heating, no barriers can be observed. After heating to 600–800°C, a high voltage (insulating) barrier is created. Heating to above 1000°C produces a 2-1/2 Volt barrier with high nonlinearity. The temperatures at which these barriers appear correspond, respectively, to temperatures at which motion of Sb and Bi first can be observed by ion backscattering techniques, and at which these elements diffuse freely.
Reactive Sputtering Deposition of Titanium Oxide Films By Means of An RF Triode Sputtering Source
Authors: Yamashita Toru , Robinson J. W. , Yamauchi H. 
Published: March 2011

AbstractTiOx thin films were fabricated by means of a reactive sputtering technique in an rf triode sputtering-deposition unit. The deposition rate was studied in detail. A ‘phase diagram’ of TiOx was determined. XPS study showed the formation of a Ti02 surface layer on TiOx thin films. Oxygen was removed by the Ar+ bombardment on Ti02 to yield Ti203.
The Influence of Irradiation Temperature on U.V. Induced Defect Creation in Dry Silica
Authors: Devine R. A. B. , Fiori C. , Robertson J. 
Published: March 2011

ABSTRACTElectron spin resonance measurements have been carried out on samples of Suprasil Wl (dry silica) subjected to ultraviolet laser radiation (λ = 248 nm, E = 5 eV/photon). Studies have been made for fixed irradiation temperature (room) variable accumulated ultraviolet dose and fixed accumulated dose (3000 J/cm2) at various irradiation temperatures in the range 110 K to 335 K. Three principal defect centers are observed. Non-bridging oxygen hole centers are created at all temperatures in the range studied with slightly higher efficiency at room temperature (ration 300 K/150 K ∼ 2.5). Comparison of the dose dependent growth curve of the 4.8 eV absorption and its isochronal annealing curve with those for the oxygen hole center clearly identify the origin of the absorption band with this defect. A threshold temperature ∼ 200 K is found for oxygen vacancy creation consistent with results on single crystalline quartz. Post irradiation annealing at 593 K eliminates the vacancy centers and the peroxy radical resonance appears. Its growth as a function of accumulated ultraviolet dose and irradiation temperature supports the hypothesis that peroxy radicals form by the trapping of diffusing, molecular oxygen at the oxygen vacancy center.
Heavy Metal Fluoride Glasses for Optical Applications
Authors: Sibley W. A. , Yeh D. C. , Suzuki Y. , Quarles G. J. , Powell R. C. 
Published: March 2011

ABSTRACTGreat progress has been made in optical device technology over the past decade. This progress brings a host of new services which include voice, data and visual communications. The realization of low loss optical fibers which give rise to long distance optical communication and the growth in information processing through computer technology will lead to an accelerating growth in the utilization of light guides and light wave communication systems. Heavy metal fluoride glasses have proved to be excellent hosts for both rare earth and 3d transition metal ions. In addition, their potential as light guides is at present unexcelled. This glass is especially promising for optical display devices, laser hosts, and electroluminescence panels. Numerous defects and impurities can be incorporated in the glass which absorb or emit light. Through optical studies of rare earth ions such as Er3+, Ho3+, Nd3+ and Pr3+ it is possible to investigate the multiphonon emission rate for optical transitions in the heavy metal fluoride materials. It is found that these particular materials have a much lower multiphonon rate than oxide glasses. This makes them attractive for room temperature devices. When 3d transition metal ions are incorporated into heavy metal fluoride glasses, the optical properties are similar in many cases to those in crystals. Inhomogeneous broadening of the absorption and emission bands occurs in the glass, but the lifetimes and oscillator strengths of the transitions in glass and crystals are of the same magnitude. Radiation damage of glasses can be detrimental to long range optical communication. It is found that the heavy metal fluoride glasses damage by the photochemical mechanism which is also dominant in highly ionic materials. Optical absorption and electron spin resonance measurements have been utilized to identify the types of radiation induced defects in these materials.
Identification of Transition Metal Sites in Fused SiO2 by X-Ray Absorption Spectroscopy
Authors: Lytle Farrel W. , Greegor Robert B. 
Published: March 2011

ABSTRACTX-ray absorption spectroscopy is used to determine valence and site symmetry for all the 3d transition metals in fused quartz prepared by the flame hydrolysis method. The results are compared with optical data on the same samples with generally good agreement.
The Varied Causes of Color in Glass
Authors: Nassau K. 
Published: March 2011

ABSTRACTAll but two of the fifteen physical and chemical mechanisms which are necessary to explain all the varied causes of color apply in one way or another to glass. These fifteen causes of color derive from a variety of physical and chemical mechanisms and are summarized in five groups with concentration on those mechanisms that apply to glass and the related glazes and enamels. Vibrations and simple excitations explain the colors of incandescence (e.g. flames, hot glass), gas excitations (neon tube, aurora), and vibrations and rotations (blue ice, water, glasses based on water). Ligand field effect colors are seen in transition metal compounds (turquoise, chrome oxide green, glasses based on copper sulfate) and impurities (ruby, emerald, many doped glasses). Molecular orbitals explain the colors of organic compounds (indigo, chlorophyll, organic glasses) and charge transfer compounds (blue sapphire, lapis lazuli, “beer-bottle” brown and chromate glasses). Energy bands are involved in the colors of metals and alloys (gold, brass, glassy metals), of semiconductors (cadmium yellow, vermillion, chalcogenide glasses), doped semiconductors (blue and yellow diamond), and color centers (amethyst, topaz, irradiated glass). Geometrical and physical optics are involved in the colors derived from dispersive refraction (rainbow, green flash, glass prism spectrum), scattering (blue sky, blue eyes, red sunset, ruby gold and opal glasses), interference (soap bubbles, iridescent beetles, cracks in glasses, interference filters), and diffraction (the corona aureole, diffraction grating spectrum).
The Mixed Alkali Effect in Sodium Rubidium Germanate Glasses
Authors: Mundy J. N. , Jin G.-L. 
Published: March 2011

ABSTRACTThe lack of general applicability of the many theoretical models for the mixed alkali effect (MAE) in glasses is briefly reviewed. Although the MAE appears to be related to the bonding affinity of alkali ions to charge compensating centers in the glass network, experimental scatter and the difficulty of comparing different glass networks have prevented systematic tests of this relationship. The present paper discusses why the mixed alkali germanate glasses should provide a glass system where the concentration and strength of charge-compensating centers can be systematically varied and the relationship to the MAE tested. Such tests are only possible if the ionic conductivity of a series of mixed alkali germanate glasses can be measured in a reproducible manner. The measurements of the ionic conductivity of two series of X(Na,Rb)2O:(1-X)GeO2glasses, with X = 0.19 and X = 0.29, respectively, suggest the necessary reproducibility can be attained.
Computed Structures of [001] Symmetrical Tilt Boundaries in Covalently Bonded Materials
Authors: Wetzel J. T. , Levi A. A. , Smith D. A. 
Published: March 2011

ABSTRACTThe dependence of the structure of (210) and (310) symmetrical [001] tilt boundaries in silicon, germanium and diamond on the Keating covalent force field (potential) has been investigated by computer modelling. We have found that the sensitivity of grain boundary structure to variations of the Keating potential depends on the local atomic arrangement at the grain boundary.