bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Dynamics of Interacting Systems: Glassy Ionic Conductors and Glass-Forming Materials
Authors: Ngai K. L. , Rizos A. K. 
Published: April 2011

ABSTRACTThe dynamics of densely packed interacting systems including glass-forming materials and glassy ionic conductors of various chemical and micro structures have been investigated experimentally by many workers, covering an immense time range from microscopic times shorter than 10−12 s to macroscopic times as long as 104 s. The short time dynamics is fundamental because it can directly reveal the microscopic mechanism of the relaxation. Several experimental investigations of structural relaxation in glass-forming substances have found that the short time dynamics shows exponential relaxation with a correlation function well described by exp(−t/τo) for t<tc where tc is temperature insensitive and has the order of magnitude of a picosecond. The correlation function then crosses over at tc to assumes the stretched exponential form, exp[−(t/τ)β], for t>tc. The relaxation times τ and τo are related by the expression τ = [tc−(1−β)τo]1/β. In this work, we focus on glassy ionic conductors and ionic glass-forming materials and experiments that employ dielectric spectroscopic and conductivity relaxation techniques, the theme of this Symposium. We show that these experimental data exhibit the same feature as described above for structural relaxation and are in accord with the predictions of the coupling model proposed by one of the authors.
Radionuclide Content of Simulated and Fully Radioactive SRL Waste Glasses: Comparison of Results from ICP-MS, Gamma Spectrometry, and Alpha Spectrometry
Authors: Wolf S. F. , Bates J. K. 
Published: April 2011

AbstractWe have measured the transuranic content of two transuranic-doped, simulated waste glasses, using inductively coupled plasma-mass spectrometry (ICP-MS), γ-spectrometry, and α-spectrometry. Average concentrations measured by each technique were within ±10% of the as-doped concentrations. We also report the transuranic content of three fully radioactive SRL waste glasses that were determined using γ- and α-spectrometry measurements to deconvolute isobaric interferences present in the ICP-MS analyses.
Kinetics of Phase Separation in Lithium Bearing HLW Alkaliborosilicate Glasses
Authors: GÖttlicher J. , Pentinghaus H. J. 
Published: April 2011

AbstractA TEM study on the kinetics of metastable phase separation in a lithium bearing HLW glass frit is presented. As nothing was known about the kinetics of metastable phase separation below the glass transformation temperature we had to carry out annealing experiments just above and below the transformation temperature, in order to achieve phase separation on a laboratory time scale- Particle growth in the WAKID5 HLW glass frit at 550 °C occurs by a diffusion controlled Ostwald ripening process (about 40 °C above Tg). Metastable phase separation in the lithium bearing glasses even at lower temperatures cannot be excluded from the present study. In NaBSi3O8 glass (Tg ≈ 580 °C) phase separation could be detected at 500 °C well below Tg after about 160 days.
Instantaneous Formation of Synroc-B Phases at Ambient Pressure
Authors: Mchale J. M. , Coppa N. V. 
Published: April 2011

AbstractThe titanate based nuclear waste immobilization medium, Synroc-B, has been synthesized at atmospheric pressure from freeze dried nitrate precursors. Complete formation of the phase assemblage (CaTiO3, CaZrTi2O7, and BaAl2Ti5O14) occurred upon calcination of the nitrate precursor after only 10 minutes at 1100°C. This improvement in the preparation conditions may lead to practical application of the material in the safe disposal of high level nuclear waste and the immobilization of other strategic nuclear materials.
Tem Study of Radiation Damage and Annealing of Neutron Irradiated Zirconolite
Authors: Lumpkin Gregory R. , Smith Katherine L. , Blake Ron G. 
Published: April 2011

AbstractNeutron irradiation was used to simulate alpha-decay damage in zirconolite, resulting in a transformation from the crystalline to the amorphous state at doses of 4–25 × 1019 n/cm2 (E ≥ 1 MeV). With increasing dose, the radiation damage microstructures resemble damage caused by: 1) alpha-decay of 232Th and 238U in natural zirconolites, 2) alpha-decay of 238Pu or 244Cm in synthetic samples, and 3) collision cascades in samples irradiated with heavy ions. Heavily damaged zirconolite recovers to a defect fluorite phase on annealing at temperatures up to 1000 °C. The main stage of structural recovery was found to occur at temperatures of 600–800 °C. The microstructures after heating depend on the initial level of damage: zirconolite grains with low to moderate levels of damage anneal to imperfect single crystals, whereas heavily damaged grains recrystallize to a polycrystalline microstructure. Complications encountered in this work include the production of fission tracks (due to trace amounts of U) and a non-uniform distribution of damage at higher dose levels (possibly due to electron beam heating).
Apatite- and Monazite-Bearing Glass-Crystal Composites for the Immobilization of Low-Level Nuclear and Hazardous Wastes
Authors: Wronkiewicz D. J. , Wolf S. F. , DiSanto T. S. 
Published: April 2011

AbstractThis study demonstrates that glass-crystal composite waste forms can be produced from waste streams containing high proportions of phosphorus, transition metals, and/or halides. The crystalline phases produced in crucible-scale melts include apatite, monazite, spinels, and a Zr-Si-Fe-Ti phase. These phases readily incorporated radionuclide and toxic metals into their crystal structures, while corrosion tests have demonstrated that glass-crystal composites can be up to 300-fold more durable than simulated high-level nuclear waste glasses, such as SRL 202U.
Sorption Mechanism of Carbon-14 by Hardened Cement Paste
Authors: Noshita K. , Nishi T. , Matsuda M. , Izumida T. 
Published: April 2011

AbstractCarbon-14 sorption by cementitious materials should be enhanced to ensure the long term safety of radioactive waste repositories. The sorption mechanism of inorganic C- 14 (CO32- was investigated using batch sorption experiments and zeta potential measurements. The results suggested that C-14 was adsorbed onto the cement surface by an electrostatic force, due to the reaction between SiO2 and CaO contained in the cementitious composition. That is, SiO2 was originally negatively charged (SiO-) in cement, but became positively charged through the interaction of Ca2+. These positive sites on the SiO2 surface adsorbed inorganic C-14. Ordinary Portland cement (OPC) did not contain enough SiO2 compared with its CaO content to produce sufficient numbers of C-14 adsorption sites. The C-14 distribution coefficient (Kd) was increased from 2,000 to 7,000 mL/g by adding SiO2 to OPC.
Evaluation of Microbially-Influenced Degradation of Massive Concrete Structures
Authors: Hamilton M. A. , Rogers R. D. , Veeh R. , Zolynski M. 
Published: April 2011

AbstractCorrosion of massive concrete structures is a costly and environmentally dangerous problem. Many low level waste disposal vaults, both above and below ground, are constructed of concrete. When the integrity of these structures is compromised, potential for soil and water contamination is significantly increased. There are literally thousands of massive concrete structures within the U.S. infrastructure that are in a serious state of disrepair due to corrosion. One potential contributing agent to the destruction of concrete structures is microbially-influenced degradation (MID). MID occurs when microorganisms in the environment produce mineral or organic acids that dissolve or disintegrate the cement matrix. Three groups of bacteria are known to create conditions that are conducive to destroying concrete integrity. They are sulfur oxidizing bacteria, nitrifying bacteria, and heterotrophic bacteria.Research is being conducted at the Idaho National Engineering Laboratory to assess the extent of naturally occurring microbially influenced degradation (MID) and its contribution to the deterioration of massive concrete structures. The preliminary steps to understanding the extent of MID, require assessing the microbial communities present on degrading concrete surfaces. Ultimately such information can be used to develop guidelines for preventive or corrective treatments for MID and aid in formulation of new materials to resist corrosion. An environmental study was conducted to determine the presence and activity of potential MID bacteria on degrading concrete surfaces of massive concrete structures. Scanning electron microscopy detected bacteria on the surfaces of concrete structures such as bridges and dams, where corrosion was evident. Enumeration of sulfur oxidizing thiobacilli and nitrogen oxidizingNitrosomonas sp.andNitrobacter sp.from surface samples was conducted. Bacterial community composition varied between sampling locations, and generally the presence of either sulfur oxidizers or nitrifiers dominated, although instances of both types of bacteria occurring together were encountered. No clear correlation between bacterial numbers and degree of degradation was exhibited.
Glass as a Waste Form for the Immobilization of Plutonium
Authors: Bates J. K. , Ellison A. J. G. , Emery J. W. , Hoh J. C. 
Published: April 2011

AbstractSeveral alternatives for disposal of surplus plutonium are being considered. One method is incorporating Pu into glass and in this paper we discuss the development and corrosion behavior of an alkali-tin-silicate glass and update results in testing Pu doped Defense Waste Processing Facility (DWPF) reference glasses. The alkali-tin-silicate glass was engineered to accommodate a high Pu loading and to be durable under conditions likely to accelerate glass reaction. The glass dissolves about 7 wt% Pu together with the neutron absorber Gd, and under test conditions expected to accelerate the glass reaction with water, is resistant to corrosion. The Pu and the Gd are released from the glass at nearly the same rate in static corrosion tests in water, and are not segregated into surface alteration phases when the glass is reacted in water vapor. Similar results for the behavior of Pu and Gd are found for the DWPF reference glasses, although the long-term rate of reaction for the reference glasses is more rapid than for the alkalitin-silicate glass.
Humid-Air and Aqueous Corrosion Models for Corrosion-allowance Barrier Material
Authors: Lee J. H. , Atkins J. E. , Andrews R. W. 
Published: April 2011

AbstractHumid-air and aqueous general and pitting corrosion models (including their uncertainties) for the carbon steel outer containment barrier were developed using the corrosion data from literature for a suite of cast irons and carbon steels which have similar corrosion behaviors to the outer barrier material. The corrosion data include the potential effects of various chemical species present in the testing environments. The atmospheric corrosion data also embed any effects of cyclic wetting and drying and salts that may form on the corroding specimen surface. The humid-air and aqueous general corrosion models are consistent in that the predicted humid-air general corrosion rates at relative humidities between 85 and 100% RH are close to the predicted aqueous general corrosion rates. Using the expected values of the model parameters, the model predicts that aqueous pitting corrosion is the most likely failure mode for the carbon steel outer barrier, and an earliest failure (or initial pit penetration) of the 100-mm thick barrier may occur as early as about 500 years if it is exposed continuously to an aqueous condition at between 60 and 70°C.
Stochastic Simulation of Pitting Degradation of Multi-Barrier Waste Container in the Potential Repository at Yucca Mountain
Authors: Lee J. H. , Atkins J. E. , Andrews R. W. 
Published: April 2011

AbstractA detailed stochastic waste package degradation simulation model was developed incorporating the humid-air and aqueous general and pitting corrosion models for the carbon steel corrosion-allowance outer barrier and aqueous pitting corrosion model for the Alloy 825 corrosion-resistant inner barrier. The uncertainties in the individual corrosion models were also incorporated to capture the variability in the corrosion degradation among waste packages and among pits in the same waste package. Within the scope of assumptions employed in the simulations, the corrosion modes considered, and the near-field conditions from the drift-scale thermohydrologic model, the results of the waste package performance analyses show that the current waste package design appears to meet the ‘controlled design assumption’ requirement of waste package performance, which is currently defined as having less than 1% of waste packages breached at 1,000 years [1]. It was shown that, except for the waste packages that fail early, pitting corrosion of the corrosion-resistant inner barrier has a greater control on the failure of waste packages and their subsequent degradation than the outer barrier. Further improvement and substantiation of the inner barrier pitting model (currently based on an elicitation) is necessary in future waste package performance simulation model.
A Phenomenological Approach to Simulating the Evolution of Radioactive-Waste Container Damage Due to Pitting Corrosion
Authors: Henshall G. A. 
Published: April 2011

AbstractThe damage to high-level radioactive-waste containers by pitting corrosion is an important design and performance assessment consideration. It is desirable to calculate the evolution of the pit depth distribution, not just the time required for initial penetration of the containers, so that the area available for release of radionuclides through the container can be estimated. A phenomenological approach for computing the time evolution of these distributions is presented which combines elements of the deterministic and stochastic aspects of pit growth. The consistency of this approach with the mechanisms believed to control the evolution of the pit depth distribution is discussed. Qualitative comparisons of preliminary model predictions with a variety of experimental data from the literature are shown to be generally favorable. The sensitivity of the simulated distributions to changes in the input parameters is discussed. Finally, the results of the current model are compared to those of existing approaches based on extremevalue statistics, particularly regarding the extrapolation of laboratory data to large exposed surface areas.
Microautoradiography in Studies of Pu(V) Sorption by Trace and Fracture Minerals in Tuff
Authors: Vaniman D. , Furlano A. , Chipera S. , Thompson J. , Triay I. 
Published: April 2011

AbstractMicroautoradiography was used to evaluate the mineralogic basis of Pu(V) retention by tuffs from Yucca Mountain, Nevada. Altered orthopyroxenes and oxide minerals are associated with high Pu retention, but are limited to specific stratigraphic horizons. A weaker but more general association of Pu with smectite occurs in most samples. Thinsections that cross fractures allow comparative studies of Pu retention by fracturelining versus matrix minerals. Using Ag metal in emulsions as a measure of underlying Pu concentration, electron-microprobe (EMP) analysis can quantify Pu retention along fracture walls and provide mineral/mineral Pu retention factors. For smectite-lined microfractures in zeolitized tuff, the smectite/clinoptilolite Pu retention factor is <80.
Localized Dryout: an Approach for Managing the Thermal-Hydrological Effects of Decay Heat at Yucca Mountain
Authors: Buscheck Thomas A. , Nitao John J. , Ramspot Lawrence D. 
Published: April 2011

AbstractFor a nuclear waste repository in the unsaturated zone at Yucca Mountain, there are two thermal loading approaches to using decay heat constructively-that is, to substantially reduce relative humidity and liquid flow near waste packages for a considerable time, and thereby limit waste package degradation and radionuclide dissolution and release. “Extended dryout” achieves these effects with a thermal load high enough to generate large-scale (coalesced) rock dryout. “Localized dryout”(which uses wide drift spacing and a thermal load too low for coalesced dryout) achieves them by maintaining a large temperature difference between the waste package and drift wail; this is done with close waste package spacing (generating a high line-heat load) and/or low-thermal-conductivity backfill in the drift. Backfill can greatly reduce relative humidity on the waste package in both the localized and extended dryout approaches. Besides using decay heat constructively, localized dryout reduces the possibility that far-field temperature rise and condensate buildup above the drifts might adversely affect waste isolation.
First-Passage-Time Modeling of Transport in Fractured Rock
Authors: Becker M. W. 
Published: April 2011

AbstractThis paper presents theory intended for the design and interpretation of tracer tests in fractured rock. The objective is to provide an understanding of experiments in which particulate and solute tracers are injected simultaneously. In such experiments, it is expected that the solute tracer will diffuse into the rock matrix, while the particulates will be confined to the fractures. The theory allows information about matrix diffusion to be extracted from the breakthrough curve. Furthermore, it can accommodate tests in which a non-ideal source is used, and where some of the withdrawn fluid is re-injected. The solution is performed in Laplace space and transformed to the time domain using a commercial spreadsheet.
Low-Impact Sampling Under an Active Solid Low-Level Radioactive Waste Disposal Unit Using Horizontal Drilling Technology
Authors: Puglisi C. V. , Vold E. L. 
Published: April 2011

AbstractThe purpose of this project was to determine the performance of a 5.5 year old active solid low-level radioactive waste disposal unit (Pit 37) located on a mesa top at Los Alamos National Laboratory (LANL), Los Alamos, NM, and to provide in-situ (vadose zone) site characterization information to Technical Area 54, Material Disposal Area (MDA) G's Performance Assessment. The vadose zone beneath Pit 37 was accessed by utilizing low-impact, air-rotary horizontal drilling technology. Core was sampled at approximately 5-foot intervals via wire-line core method in 3 horizontal holes fanning out below Pit 37. Samples were screened and prepared in-field following LANL Environmental Restoration Project guidelines. Samples were transferred from the field to the Mobile Radiation Analysis Laboratory for initial radiological screening. Following screening, samples were delivered to an analytical lab for analyses including moisture content, 23 inorganic compounds, 60 volatile organic compounds, 68 semivolatile organic compounds, tritium, lead 210, radium 226 's Pit 37 is performing well and no significant liquid phase migration of contaminants has occurred.
Deformation Mechanism of Basic Rock During Long-Term Compression: Area of Hlw Repository Design, Chelyabinsk District, Russia
Authors: Petrov V. A. , Zviagintsev L. I. , Poluektov V. V. 
Published: April 2011

AbstractA combination of ultrasound, mechanical and petrographic results for long-term experimental compression of greenschist facies porphyritic andesite tuffs indicate a deformation mechanism that depends upon the mineral composition, textural-structural features of the rocks and the orientation of compression relative to the rock textures. Three dry samples of rock were investigated. Coaxial compression of a massive sample for 816 hours and a foliated sample for 1176 hours (pressure orthogonal to foliation) is characterized by solidification when the rocks are temporarily metastable. Compressive strength of the first sample is 850 kg/cm2 and of the second one, 800 kg/cm2. Experimentally, the rock behavior changes from a plastic to a brittle regime of deformation. In contrast, compression of the foliated sample parallel to foliation causes disintegration along the foliation within 480 hours without solidification. The rock is liable to brittle deformation and its compressive strength is 500 kg/cm2. These results may have implications for characterization of near-field processes in connection with numerous subhorizontal zones of schistosity within the strata that are targeted for underground disposal of high-level wastes (HLW) in the Mayak radiochemical complex area.
Mechanism of Saleeite Formation at the Koongarra Secondary Ore Deposit
Authors: Murakami Takashi , Isobe Hiroshi , Ohnuki Toshihiko , Sato Tsutomu , Yanase Nobuyuki , Kiyoshige Junko 
Published: April 2011

AbstractRock samples in the secondary ore deposit at Koongarra, Australia, were examined mineralogically to clarify the formation mechanism of saléeite (Mg(UO2)2(PO4)2.10H2O), a major secondary uranium mineral in the secondary ore deposit. Sklodowskite (MgSi2U2O11.7H2O) veinlets, present upstream of the ore deposit, are partially replaced by saléeite. Most grains of apatite (Ca5(P04)3F), an accessory mineral of the host rock, are also replaced by saléeite. Thermodynamic calculations by EQ3NR showed that the present Koongarra ground waters are undersaturated with respect to saléeite and also suggested that saléeite can be precipitated under the condition of higher U or P concentrations. Such conditions can be created at the reaction interfaces of dissolving sklodowskite, which releases U, or dissolving apatite, which releases P. The present study indicates that saléeite is formed by local microscale saturation upstream of the secondary ore deposit, which is different from the formation mechanism of saléeite downstream of the ore deposit, where saléeite microcrystals of 1 – 20 nm in size form by catalysis on iron minerals, the weathering products of the host rock.
Trace Element Distribution Patterns in Magnetically Separated Fractions of Fracture Filling Material
Authors: Cui D. , Eriksen T. E. 
Published: April 2011

AbstractThe distribution patterns of trace elements in magnetically separated fractions of a granite fracture filling material have been studied using instrumental neutron activation analysis. The distribution patterns of trace elements with similar ionic radii and the same charge, Fe-Co, Rb-Cs, Hf-Zr, U-Th, and light REE, were found to be similar. Whereas most of the elements are found in higher concentrations in the more clay rich fractions, Rb and Cs display a more homogeneous distribution.
Optical Degradation of Poly(P-PHENYLENE VINYLENE)
Authors: So S. K. , Chan M. H. , Hon C. S. , Leung Louis M. 
Published: April 2011

ABSTRACTThe influence of laser irradiation on an electroluminescent polymer, poly(2,5-di-n-hexyloxy-l,4- phenylene vinylene) is studied. Photoluminescence, infrared spectroscopy, and photothermal deflection spectroscopy were used to identify changes in the optical properties of the polymer after laser irradiation. It is found that optical irradiation leads to the opening of the vinyl double bond and decrease in conjugation length. Photo-oxidation of the polymer is believed to be responsible for the optical degradation of the polymer.
New Developments in Thermally and Chemically Stable Nonlinear Optical Chromophores for E-O Device Applications
Authors: Rao Varanasi Pushkara , Jen Alex K-Y. , Drost Kevin J. , Cai Y. M. 
Published: April 2011

ABSTRACTA new class of second order nonlinear optical chromophores resulted from the replacement of the most reactive CN group in tricyanovinylthiophene derivatives with aryl units, have been designed and synthesized. It was shown that these chromophores provide excellent tradeoffs among many relevant properties such as molecular nonlinearity, linear absorption at 830 nm, inherent thermal stability, chemical stability in processing solvents as well as host polymer matrices at high temperatures and attenuation at 830 nm.