bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Development of a High Strength Cementitious Tooling/Molding Material
Authors: Wise S. , Satkowski J. A. , Scheetz B. , Rizer J. M. , Mackenzie M. L. , Double D. D. 
Published: March 2011

AbstractThe composition and fabrication of a high strength cementbased composite containing graded stainless steel aggregate and fine silica are described. The microstructure, physical properties and temperature cycling durability of this material are examined and some examples are given of technological applications as a molding/tooling material.
Polymer Impregnation of an Impervious Cementitious Composite Material
Authors: Bright Randall P. , Wise Sean , Mackenzie Mark I. 
Published: March 2011

AbstractWell compacted, silica fume-modified ordinary Portland cement pastes are well known for their low permeability. This quality can be maintained to temperatures slightly in excess of 200°C. Above this temperature, however, a continuous pore structure develops, making the material permeable and therefore unsuitable for high temperature applications (250–400°C) where vacuum integrity is necessary. To overcome this obstacle the permeability can be exploited for impregnating the concrete with an organic polymer. Organic polymers traditionally employed for impregnated concretes are not thermally stable enough to be used at high temperatures. Therefore, a high temperature-resistant organic resin has been studied for this application. The optimum conditions for impregnating this viscous resin into a high strength mortar have been investigated.
The Microstructure of High Strength Cement Pastes
Authors: Sinclair W. , Groves G. W. 
Published: March 2011

AbstractThe microstructures of high strength pastes of OPC and high alumina cements prepared by the high shear mixing of a low water/cement ratio paste with water soluble polymers have been studied by transmission electron microscopy. In the case of high strength OPC, the usual hydration products are present, however, the CSH gel lacks the fibrillar morphology often observed in conventional cements. Pastes based on high alumina cement do not contain the normal crystalline calcium aluminate hydrates but a small quantity of gel containing the organic polymer forms a continuous network structure bonding clinker grains. Microanalysis of the polymer phase in high alumina cement revealed the presence of Ca and Al while Ca-rich interstitial gel material was found in OPC pastes.
Relationships between Strength and Microstructure for Cement-Based Materials: an Overview
Authors: Mindess Sidney 
Published: March 2011

AbstractThe mechanical properties of cement-based materials must be controlled by the microstructure, pore geometry and chemical composition of the cement, by the properties of the aggregate, and by the nature of the cement-aggregate bond. While the precise form of the strength vs. microstructure relationship is as yet only imperfectly understood, enough is known to permit us to predict what alterations in the microstructure are required for the production of materials with very high strengths. There are also techniques available for reducing the brittleness that is often a characteristic of high-strength materials. The present paper presents an overview of the strength vs. microstructure relationships that can be used to predict the properties of high strength cement-based materials, and a brief review of some of the methods for achieving high strengths.
The Effect of Various Lead Species on the Leaching Behavior of Borosilicate Waste Glass
Authors: lehman Richard L. , Kuchinski Frank A. 
Published: March 2011

AbstractA borosilicate nuclear waste glass was static leached in pure water, silicate water, and brine solution. Three different forms of lead were included in specified corrosion cells to assess the extent to which various lead species alter the leaching behavior of the glass. Weight loss data indicated that Pbm and Pb0 greatly reduce the weight loss of glass when leached in pure water, and similar effects were noted in silicate and brine. Si concentrations, which were substantial in the glass-alone leachate, were reduced to below detection limits in all pure water cells containing a lead form. Lead concentration levels in the leachate were controlled by lead form solubility and appeared to be a significant factor in influencing apparent leaching behavior. Surface analysis revealed surface crystals, which probably formed when soluble lead in the leachate reacted with dissolved or activated silica at the glass surface. The net effect was to reduce the release of some glass constituents to the leachate, although it was not clear whether the actual corrosion of the glass surface was reduced. Significantly different corrosion inhibiting effects were noted among lead metal and two forms of lead oxide.
Early Stages of Film Formation During the Leaching of Radioactive Waste Glasses
Authors: Houser C. A. , Pantano C. G. 
Published: March 2011

AbstractThe early stages of surface alteration-layer formation were examined during the leaching of some candidate radioactive waste glasses. The composition-depth profiles of the leached surfaces were obtained with sputter-induced photon spectroscopy (SIPS) and secondary-ion mass spectroscopy (SIMS). It was observed that the formation of multiple surface layers is a general feature of the glass dissolution process. The sequence of the layer compositions depends upon the order in which solubility limits are attained in solution, the adsorption or precipitation of insoluble hydrates at the glass/water interface, and subsequent incorporation of these insoluble hydrates behind the advancing reaction front. The boundary between the surface layer and bulk glass is sharp.
NNWSI Waste Form Performance Test Development
Authors: Bates John K. , Gerding Thomas J. 
Published: March 2011

AbstractA test method has been developed to measure the release of radionuclides from the waste package under simulated NNWSI repository conditions, and to provide information concerning materials interactions that may occur in the repository. Data from 13 weeks of unsaturated testing are discussed and compared to that from a 13 week analog test. The data indicate that the waste form test is capable of producing consistent, reproducible results that will be useful in evaluating the role of the waste package in the long-term performance of the repository.
Parametric Testing of A DWPF Borosilicate Glass
Authors: Bazan F. , Rego J. 
Published: March 2011

AbstractA series of tests have been performed to characterize the chemical stability of a DWPF borosilicate glass sample as part of the Waste Package Task of the NNWSI Project. This material was prepared at the Savannah River Laboratory for the purpose of testing the 165-frit matrix doped with a simulated non-radioactive waste. All tests were conducted at 90°C using deionized water and J-13 water (a tuffaceous formation groundwater). In the deionized water tests, both monoliths and crushed glass were tested at various ratios of surface area of the sample to volume of water in order to compare leach rates for different sample geometries or leaching times. Effects on the leach rates due to the presence of crushed tuff and stainless steel material were also investigated in the tests with J-13 water.
Mass Transfer in a Geologic Environment
Authors: Zavoshy S. J. , Chambre' P. L. , Pigford T. H. 
Published: March 2011

AbstractA new analytical solution is presented that predicts the rate of dissolution of species from a waste package surrounded by a wet porous medium. By equating the rate of diffusive mass transfer into the porous rock to the rate of liquid-surface chemical reaction, an analytical solution for the timedependent dissolution rate and the time-dependent concentration of dissolved species at the waste surface is obtained. From these results it is shown that for most of the important species in a package of radioactive waste the surface liquid quickly reaches near-saturation concentrations and the dissolution rate can be predicted by the simpler theory that assumes saturation concentrations in the surface liquid.
Leaching Studies of Non-Metallic Materials for Nuclear Fuel Immobilization Containers
Authors: Onofrei M. , Raine D. K. , Brown L. , Stanchell F. 
Published: March 2011

AbstractThe leaching behaviour of various ceramics was studied as part of a program to evaluate their potential use as container material for very long term containment of nuclear fuel waste under conditions of deep geologic disposal.Samples of four grades of Al2O3, stabilized ZrO2, TiO2, a cermet (70% A12O3- 30% TiC) and porcelain have been leached in deionized distilled water, Standard Canadian Shield Saline Solution (SCSSS), and SCSSS plus 20% Na-bentonite under static conditions at 100°C for periods up to 120 d.The results of these ongoing leaching experiments suggest that the controlling features of the ceramic leaching process were leachant composition, and the presence and concentration of ions in the solution capable of preferentially precipitating on the ceramic surface, i.e., silicon, Mg2+, Ca2+, etc. Weight losses were determined after leaching. The initial leach rates showed a dependence upon ceramic purity and the processing used to prepare the ceramics, as well as the leachant composition. Also, it was apparent that the decrease of leach rates with time occurred as a result of the ceramic components in the leachant approaching their saturation limits.
Behavior of Natural Uranium, Thorium and Radium Isotopes in The Wolfcamp Brine Aquifers, Palo Duro Basin, Texas
Authors: Laul J. C. , Smith M. R. , Hubbard N. 
Published: March 2011

AbstractPreviously reported results for Palo Duro deep brines show that Ra is highly soluble and not retarded. Relative to Ra, U and Th are highly sorbed. Uranium, like thorium, is in the +4 valence state, indicating a reducing environment. Additional data reported here support these results. However, one Wolfcamp brine sample gives somewhat different results. Radium appears to be somewhat sorbed. Uranium is largely in the +6 valence state, indicating a less reducing condition. In all brines, kinetics for sorption (228Th) and desorption (224Ra) are rapid. This Wolfcamp brine was tested for the effects of colloids for Ra, U, and Th concentrations. No effects were found.
The Thermodynamics and Geochemistry of Ca, Sr, Ba, and Ra Sulfates in Some Deep Brines From the Palo Duro Basin, Texas
Authors: Melchior Daniel , Langmuir Donald , Rogers Pamela S. Z. , Hubbard Norman 
Published: March 2011

AbstractThe work reported here involved application of the ion-interaction approach of Pitzer [1] [2] to model the activities of some major and minor cations and major anions in deep brine systems at elevated temperatures and pressures.The solubilities of anhydrite (CaS04), gypsum (CaSO4·2H2O), celestite (SrS04), barite (BaS04), and radium sulfate (RaSO4) in brines from the Wolfcamp Formation and granite wash facies, Palo Duro Basin, Texas, were modeled using ion-interaction equations. Waters with ionic strengths ranging from 2.89 to 4.76 m, and temperatures and pressures up to 40°C and 130 bars were sampled from five horizons in three wells, at depths between 970 and 1,670 meters. Theoretical solubility products as a function of temperature and pressure were obtained for comparison with ion activity products computed using ion-interaction theory. The effect of temperature on model calculations was found to reside almost entirely in the Debye-Hückel AΦ parameter, which accordingly was corrected for brine temperatures [3].Modeling results indicated that all five brines are saturated with respect to anhydrite and celestite, and three of the five with respect to barite. Saturation may result from hydrologic connection with adjacent overlying evaporite units, or increased Ca, Sr and Ba concentrations caused by their desorption from clays. Radium concentrations, which range from 10-11.3 to 10-12.7 m, are not controlled by RaSO4 solubility or adsorption, but probably by solid solution in other sulfate minerals in these low pH (4.4 – 6.3) high calcium (0.18 – 0.52 m) brines [4] [5].
Hydrothermal Interaction of Topopah Spring Tuff With J-13 Water as a Function of Temperature
Authors: Knauss Kevin G. , Delany J. M. , Beiriger W. J. , Peifer D. W. 
Published: March 2011

AbstractIn support of the Nevada Nuclear Waste Storage Investigations Project experiments were conducted to study the hydrothermal interaction of rock and water representative of a potential repository in tuff. These experiments provided data relevant to near-field repository conditions that can be used to: assess the ability to use “accelerated” tests based on the SA/V (surface area/volume) parameter and temperature; allow the measurement of chemical changes in phases present in the tuff before reaction as well as the identification and chemical analysis of secondary phases resulting from hydrothermal reactions; and demonstrate the usefulness of geochemical modeling in a repository environment using the EQ3/6 thermodynamic/kinetic geochemical modeling code. Crushed tuff and polished wafers of tuff were reacted with a natural ground water in Dickson-type gold-cell rocking autoclaves which were periodically sampled under insitu conditions. Results were compared with predictions based on the EQ3/6 geochemical modeling code. Eight short-term experiments (2 to 3 months) at 150°C and 250°C have been completed using tuff from both drillcore and outcrop. Long-term experiments at 90°C and 150°C using drillcore polished wafers are in progress. This paper will focus on the results of the 150°C and 250°C experiments using drillcore polished wafers.
Rubidium-Strontium Geochronologic Systematics in Igneous Contact Zones: Analog for 90-Sr and 137-Cs Behavior in the Near Field
Authors: Brookins D. G. 
Published: March 2011

AbstractThe behavior of 90-Sr and 137-Cs in the near field of a HLW package can be investigated by use of Rb-Sr geochronologic information from igneous contact zones. The chemical behavior of 90-Sr is identical to other Sr isotopes, and Cs behavior is very similar to that of Rb. During igneous intrusion, the effect of heat from the igneous rock, coupled with fluid action, is to perturb Rb-Sr systematics of minerals in the intruded rock. Rb-Sr redistribution diagrams are useful not only for indirectly dating the time of intrusion, but also for determining the extent of closed versus open system conditions in the contact zones. Once open or closed system behavior is determined, the Rb-Sr systematics can be evaluated in terms of diffusion, fluid-induced metasomatism, selective dissolution, other, and coupled processes. All these can be discussed in terms of time-temperaturefluid compositional parameters. Rb migration is controlled predominantly by fluid flow, while diffusion models better explain some Sr isotopic behavior Cs, from geochemical arguments, should be less mobile than Rb. In most cases, even when temperature of the intrusive is 800–1200°C the cooling period on the order of 104 – 105 years, and in a highly convective system, Sr and Rb mobility is on the order of only microns to meters.
Gamma and Alpha Radiolysis of Salt Brines
Authors: Gray W. J. , Simonson S. A. 
Published: March 2011

AbstractGamma radiolysis of Permian Basin brine leads to equilibrium gas pressure of about 100 atm. at 75°C and about 40 atm. at 150°C, providing the gas space is very small and/or the total dose is very high. Dose rate dependence is being investigated but is not yet established. Alpha radiolysis of Permian Basin brine is still being evaluated, but it is clear that equilibrium gas pressures will be much higher than with gamma radiolysis. In addition, alpha radiolysis of brine results in a very high solution redox potential. Gas compositions in all cases have been about two parts H2 to one part O2. Efforts to simulate these results with computer models have been quite successful.
Application of XPS and Nuclear Technique to the Study of the Gel Layers Formed Under Different Redox Conditions on Leached Glasses
Authors: Manara A. , Lanza F. , Ceccone G. , Mea G. Della , Salvagno G. 
Published: March 2011

AbstractSurface analysis has been conducted on samples leached in a Soxhlet apparatus at 100°C in presence and in absence of air. The XPS and RBS techniques were applied to analyse the content of the silicon, iron and uranium while the nuclear reaction method was utilized to analyse the hydrogen content. The anoxic environment favours the release of iron while decreasing the dissolution of uranium. Hydrogen content is always higher in samples leached in presence of air.Silicon depletion is evident in all cases. The diffusion process seems to regulate the growth of the layer on the glass surface. After long leaching time a detachment, at least partial, of this layer is observed.
Alpha-Recoil Damage in Thorianite and Uraninite: Effect on Dissolution and Time-Scale for Spontaneous Annealing of Damage
Authors: Eyal Yehuda , Fleischer Robert L. 
Published: March 2011

AbstractUsing natural ThO2 and UO2 in which radiation damage has accumulated over geologic periods, we have measured the relative in dissolution rates bicarbonate-carbonate solutions of the actinide isotopes 238U, 234U, 232Th, 230Th, and 228Th. An enhanced dissolution by a factor of 2 to 7 of the short lived (1.9 yr) 228Th relative to that of its structurally incorporated primary isotope 232Th indicates the presence of severe localized atomic displacement damage created by alpha-recoil atoms. In contrast, the relatively small (<20%) isotopic fractionation between the radiogenic 8.0 × 104 yr- 230Th isotope and 232Th, and between the radiogenic 2.5 × 105 yr- 234U isotope and its primary structurally incorporated isotope 238U, suggests the nearly complete annealing of the alpha-recoil damage during a period of less than 105 yr. An estimate of the mean fading time for the leachable damage is 15,000 yr.
The Purpose of the Materials Characterization Center
Authors: Mendel John E. 
Published: March 2011

AbstractThe Materials Characterization Center (MCC) at the Pacific Northwest Laboratory is the experimental arm of the Materials Characterization Organization (MCO), which was established by the U.S. Department of Energy (DOE) in FY 1980 to ensure high quality characterization and qualification of waste package materials essential to the reliable performance of DOE nuclear waste management programs. The MCC is responsible for publishing key test methods and data in the Nuclear Waste Materials Handbook (DOE/TIC-11400) after the methods and data have been reviewed and approved by the Materials Review Board (MRB), which is the other major operating arm of the MCO.The MCC is carrying out its responsibilities in several ways. It sponsors a continuing series of workshops that address materials characterization test method issues. It supplies well-characterized reference and testing materials for use by the DOE nuclear waste management programs. It develops generic test methods and supports the repository waste package projects in developing selected site-specific test methods and performing confirmatory testing of these methods. When these test methods are approved by the MRB they constitute the formal tests to be used by laboratories to test and qualify materials, evaluate waste package components, and assure compliance with standards and/or specifications for the final product.
Materials Interactions Test Method to Measure Radionuclide Release from Waste Forms Under Repository-Relevant Conditions
Authors: Strickert Richard G. , Erikson Robert L. , Shade John W. 
Published: March 2011

AbstractAt the request of the Basalt Waste Isolation Project, the Materials Characterization Center has collected and developed a set of procedures for a waste form compliance test method (MCC-14.4). The purpose of the test is to measure the steady-state concentrations of specified radionuclides in solutions contacting a waste form material. The test method uses a crushed waste form and basalt material suspended in a synthetic basalt groundwater and agitated for up to three months at 150°C under anoxic conditions. Elemental and radioisotopic analyses are made on filtered and unfiltered aliquots of the solution. Replicate experiments are performed and simultaneous tests are conducted with an approved test material (ATM) to help ensure precise and reliable data for the actual waste form material. Various features of the test method, equipment, and test conditions are reviewed. Experimental testing using actinide-doped borosilicate glasses are also discussed.
Improved Uranium Recovery from the Process Streams in an Electroplating Facility
Authors: Pickett John B. 
Published: March 2011

AbstractCylindrical uranium slugs are used as irradiation targets in the production reactors at the Savannah River Plant. These slugs are first chemically etched, nickel plated, encased in aluminum, inspected, and individually pressure tested. An improved process was developed to recover the uranium from the acidic etching streams by controlling pH and the PO4 to U ratio so that the precipitation of the uranium as hydrogen uranyl phosphate was maximized. Bench scale tests demonstrated that the recovery of uranium could be increased to greater than 99.9% (vs. the current level of about 95% recovery). The recommended changes involved the addition of process effluent “hold” tanks. The addition of the various process streams to the neutralization/precipitation tank could therefore be controlled to maintain a consistent ratio of uranyl nitrate and phosphoric acid. Also, it was determined that a strong caustic solution (resulting from the dissolution of rejected aluminum slugs) could be utilized to neutralize the nitric and phosphoric acid solutions. The buffering action of the aluminum in the “caustic recovery solution” would reduce the sensitivity of the hydrogen uranyl phosphate precipitation to the phosphate ion concentration.
Evaluation of Materials Performance in a Large-Scale Glass Melter after two Years of Vitrifying Simulated SRP Defense Waste
Authors: Iverson Daniel C. , Bickford Dennis F. 
Published: March 2011

AbstractThe Large Slurry Fed Melter (LSFM) at the Department of Energy's Savannah River Plant recently completed two years of service and was shut down for evaluation. The melter operating history is reviewed and the condition of the refractories and metal components is described. The excellent condition of the LSFM verifies the expected performance of the materials of construction, and indicates that a two year melter life is achievable in the Defense Waste Processing Facility (DWPF).
Diffusivities of Cesium and Strontium in Concretes and in Mixtures of Sodium Bentonite and Crushed Rock
Authors: Muurinen Arto , Rantanen Juha , Ovaskainen Raisa 
Published: March 2011

AbstractDiffusivities of Cs and Sr in concretes and in mixtures of sodium bentonite and crushed rock were measured. The order of magnitude of the apparent diffusivities (Da) for Cs and Sr in concretes was −14−10−13 m2/s and in the mixtures of bentonite and crushed rock 10−13− 10−11 m2/s. The calculated effective diffusivities (De) in the mixtures of bentonite and crushed rock seemed in some cases to exceed the corresponding values in water, which suggests that the pore diffusion/sorption model cannot explain the transport phenomena in all cases.The experiments where the sorption factors were varied in the diffusion samples suggest that the nuclides diffuse also while being sorbed. A combined pore diffusion-surface diffusion model has been used to explain the transport and the corresponding diffusivities have been evaluated. This paper will give the measured diffusion and sorption data and discuss the models used to describe diffusion in porous sorbing agents.