bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wipp Waste Package Testing on Simulated DHLW: Emplacement
Authors: Molecke Martin A. 
Published: March 2011

AbstractSeveral series of simulated (nonradioactive) defense high-level waste (DHLW) package tests have recently been emplaced in the WIPP, a research and development facility authorized to demonstrate the safe disposal of defense-related wastes. The primary purpose of these 3-to-7 year duration tests is to evaluate the in situ materials performance of waste package barriers (canisters, overpacks, backfills, and nonradioactive DHLW glass waste form) for possible future application to a licensed waste repository in salt. This paper describes all test materials, instrumentation, and emplacement and testing techniques, and discusses progress of the various tests.These tests are intended to provide information on materials behavior (i.e., corrosion, metallurgical and geochemical alterations, waste form durability, surface interactions, etc.), as well as comparison between several waste package designs, fabrications details, and actual costs.These experiments involve 18 full-size simulated DHLW packages (approximately 3.0 m x 0.6 m diameter) emplaced in vertical boreholes in the salt drift floor. Six of the test packages contain internal electrical heaters (470 W/canister), and were emplaced under approximately reference DHLW repository conditions. Twelve other simulated DHLW packages were emplaced tinder accelerated-aging or overtest conditions, including the artificial introduction of brine, and a thermal loading approximately three to four times higher than reference. Eight of these 12 test packages contain 1500 W/canister electrical heaters; the other four are filled with DHLW glass.
Corrosion of Candidate Iron-Base Waste Package Structural Barrier Materials in Moist Salt Environments
Authors: Westerman R. E. , Pitman S. G. 
Published: March 2011

AbstractMild steels are considered to be strong candidates for waste package structural barrier (e.g., overpack) applications in salt repositories. Corrosion rates of these materials determined in autoclave tests utilizing a simulated intrusion brine based on Permian Basin core samples are low, generally μm (1 mil) per year. When the steels are exposed to moist salts containing simulated inclusion brines, the corrosion rates are found to increase significantly. The magnesium in the inclusion brine component of the environment is believed to be responsible for the increased corrosion rates.
Technetium and Neptunium Reactions in Basalt/Groundwater Systems
Authors: Meyer R. E. , Arnold W. D. , Kelmers A. D. , Kessler J. H. , Clark R. J. , Johnson J. S. , Young G. C. , Case F. I. , Westmoreland C. G. 
Published: March 2011

AbstractSorption isotherms and apparent concentration limits for Tc(VII) and Np(V) for a variety of groundwater/basalt systems were determined using Grande Ronde basalt samples representative of the Hanford Site candidate high-level waste repository. Under oxic redox conditions (air present), little or no sorption of technetium was observed; neptunium exhibited low to moderate sorption ratios. Under anoxic redox conditions (oxygen-free), low to moderate sorption of technetium was often observed, but the extent of sorption was highly dependent upon the groundwater composition and the method of pretreatment (if any) of the basalt. Sorption isotherms for technetium under reducing redox conditions (hydrazine added) indicate an apparent concentration limit of approximately 10−6mol/L Tc. No apparent concentration limit was found for neptunium for concentrations in groundwater up to.∼10−6mol/L and 8 × 10−7mol/L under oxic and reducing (hydrazine added) redox conditions, respectively.Valence control and valence analysis experiments suggest that the sorption or precipitation of Tc and Np from groundwater in the presence of basalt may result from a heterogeneous reaction occurring on the surface of the basalt. One of the critical factors of this reduction reaction appears to be the accessibility of the reactive ferrous iron component of the basalt. The laboratory simulation of groundwater redox conditions representative of the repository environment through the use of solution phase redox reagents is of questionable validity, and information obtained by such experimental methods may not be defensible for site performance assessment calculations. Anoxic experiments conducted in an argon-filled glove box appear better suited for the laboratory simulation ofin situredox conditions.
Diffusion of Plutonium in Compacted, Brine-Saturated Bentonite
Authors: Nowak E. J. 
Published: March 2011

AbstractDiffusivities were measured for plutonium in brine-saturated compacted Wyoming bentonite. Complexities of the solution chemistry and retardation of transuranics necessitate diffusion studies under conditions that are specific for repository host rock types in this case salt. Diffusivity values in the range of 10−15 to 10−14 m2/s were obtained for bentonite at a packing density of 1800 kg/m3. That density was obtained by compaction at 15 i0Pa, a typical lithostatic pressure in a repository in salt at 650 m depth. Even a 0.05 m (2 inch) thick bentonite-containing engineered barrier could decrease radionuclide release rates by approximately 4 orders-of-magnitude if the diffusivity for that radionuclide were in the observed range of 10−15 to 10−14 m2/s. These results confirm the effectiveness of uncompacted bentonite-containing materials as engineered barriers for radioactive waste isolation.
Spent UO2-fuel Dissolution. Tentative Modelling of Experimental Apparent Solubilities
Authors: Bruno J , Forsyth R S , Werme L O 
Published: March 2011

AbstractExperimentally measured concentrations in spent UO2-fuel leachates are reported for uranium and plutonium for contact times ranging from 14 days to 2 years at different pH. The experimental results for uranium clearly indicated saturation. This interpretation was supported by comparison with theoretical solubilities, calculated using a modified SOLGASWATER program. The calculated solubilities were found to agree well with the experimentally determined concentrations.
Conceptual Model for Deriving the Repository Source Term
Authors: Alexander D. H. , Apted M. J. , Liebetrau A. M. , Luik A. E. Van , Williford R. E. , Doctor P. G. 
Published: March 2011

AbstractPart of a strategy for evaluating the compliance of geologic repositories with Federal regulations is a modeling approach that would provide realistic release estimates for a particular configuration of the engineered-barrier system. The objective is to avoid worst-case bounding assumptions that are physically impossible or excessively conservative and to obtain probabilitistic estimates of (1) the penetration time for metal barriers and (2) radionuclide-release rates for individually simulated waste packages after penetration has occurred. The conceptual model described in this paper will assume that release rates are explicitly related to such time-dependent processes as mass transfer, dissolution and precipitation, radionuclide decay, and variations in the geochemical environment. The conceptual model will take into account the reduction in the rates of waste-form dissolution and metal corrosion due to a buildup of chemical reaction products. The sorptive properties of the metal-barrier corrosion products in proximity to the waste form surface will also be included. Cumulative releases from the engineered-barrier system will be calculated by summing the releases from a probabilistically generated population of individual waste packages.
Hydrothermal Waste Package Interactions With Methane-Containing Basalt Groundwater
Authors: McGrail B. P. 
Published: March 2011

AbstractHydrothermal waste package interaction tests were conducted with a mixture of crushed glass, basalt, and steel in methane-containing synthetic basalt groundwater. In the absence of gamma radiolysis, methane was found to have little influence on the corrosion behavior of the waste package constituents. Under gamma radiolysis, methane was found to significantly lower the solution oxidation potential when compared to identical tests without methane. In addition, colloidal hydrocarbon polymers that have been produced under the irradiation conditions of these experiments were not formed. The presence of the waste package constituents apparently inhibited the formation of the polymers. However, the mechanism which prevented their formation was not determined.
Probabilistic Analysis of Human Intrusion in a High Level Nuclear Waste Repository in Salt Using Draft EPA Assumptions
Authors: Harper William V. , Raines Gilbert E. 
Published: March 2011

AbstractThe Office of Nuclear Waste Isolation (ONWI) has planned performance assessments that will quantify various performance measures for the eventual licensing of a repository in salt. In addition to studying “expected” conditions, selected discrete event scenarios must be analyzed. This paper presents a probabilistic analysis of a human intrusion scenario in which boreholes may be drilled into the repository, contact nuclear waste, and release the radionuclides to the environment. A stochastic analysis using draft EPA limiting factors regarding probability of drilling and quantities of water flow is compared to the proposed EPA 10,000 year limits. The years in which boreholes penetrate the repository are probabilistically determined in each iteration of the analysis. For each borehole, the probability of contacting radioactivity is an increasing function of time. When a borehole does make contact with radioactivity, the curie release of a given nuclide is a function of solubility limits and current inventory. Prediction intervals and complementary cumulative probability distribution functions are developed for the curie release as a fraction of the EPA limits. Radionuclide releases are small fractions of the EPA limits. This study shows that there is a high expectation that the EPA requirements would be met with a repository in salt.
Effects of Radiation-Induced Stress on the Chemical Durability of Nuclear Waste Glasses
Authors: Ougouag Abderrafi M. , Machiels Albert J. 
Published: March 2011

AbstractThe growth of stresses in irradiated glasses is modeled, and the resulting effects on chemical durability are evaluated. It is shown that in actinide-doped glasses, maximum stresses are small when compared to those that act on a plane parallel to the ion tracks of an implanted glass, at equivalent fluences. The theory also offers an explanation for the apparent change in the dissolution enhancement factor with fluence in ion-implantation experiments.
A Generalized Model for the Analysis of Groundwater Radiolysis
Authors: Nicolosi Stephen L. 
Published: March 2011

AbstractA generalized groundwater radiolysis model which is under development at Battelle-Columbus is described. This model uses a 55 reaction basis set for the radiolysis of the solvent. The basis set of reactions was chosen from the literature after comparing several descriptions against experimental data. This basis set has been augmented with 17 additional reactions to allow the description of the radiolysis of groundwater containing iron. The development of this mechanism is described, and comparisons with experimental data are shown.
Test Methods to Predict Long-Term Corrosion of Container Materials in Repositories
Authors: Merz Martin D. , Wang Rong 
Published: March 2011

AbstractMCC test methods in support of basalt, salt and tuff repositories are described. The methods consist of three general corrosion tests for basalt, two general corrosion tests and three stress corrosion tests for salt, and two general corrosion tests for tuff. The tests encompass the various conditions that are expected in the different repositories. A summary is provided of experimental activities of the MCC, and detailed results of MCC 105.1 Test Method for Long Term General Corrosion in a Basalt Repository (Static System) for standardized, benchmark conditions are presented. A summary of the statistical treatment of data is provided with examples of confidence intervals and the dependence on number of test vessels. The total relative standard deviation for the mean corrosion penetration rate was 11.4% for a mean corrosion penetration rate of 0.0244 mm/yr for 120 d tests at 100°C.
The Chemical Environment in Cements
Authors: Glasser F. P. , Angus M. J. , McCulloch C. E. , Macphee D. , Rahman A. A. 
Published: March 2011

AbstractThe alkalinity of Portland cements is responsible for precipitation and low solubility of many radwaste species. The sources of alkalinity are evaluated and two chemical models, based on experimental and theoretical data presented enabling the effect of blending agents (PFA, silica fume, etc.) to be evaluated and the alkalinity of the system at longer ages predicted. The data take the form of a solubility model which is applicable to non-heat generating wastes.
Physical Properties of Saltstone: Physical Properties of Saltstone: A Savannah River Plant Waste Form
Authors: Langton Christine A. 
Published: March 2011

AbstractA cement-based waste form, “saltstone,” has been designed for disposal of Savannah River Plant low-level radioactive salt waste. Laboratory and field tests indicate that this stabilization process greatly reduces the mobility of all of the waste constituents in the surface and near-surface environment. Bulk properties of this material have been tailored with respect to salt leach rate, permeability, and compressive strength. Microstructure and mineralogy were characterized by SEM and x-ray diffraction analyses.Compressive strength was found to increase as the water to cement ratio decreased. Porosity and mean pore size increased with increasing water to cement ratios. Bulk diffusivities of the various ions dissolved in the pore solutions were also found to increase as water to cement ratios increased.
Leachability of Cement Encapsulated West Valley Radwaste Streams
Authors: Grant D. C. , Smeltzer E. E. , Skriba M. C. , Cwynar J. C. , Eisenstatt L. R. 
Published: March 2011

AbstractLow-level radwaste streams to be generated during the cleanup of the nuclear fuel reprocessing plant at West Valley, New York will require disposal in an environmentally acceptable manner. A study was conducted to determine if presently identified waste streams could be encapsulated in cement to produce a waste form which complies with present NRC guidelines for the disposal of.low-level radwaste streams. One waste stability guideline is leachability which was examined in this study. The leach testing was performed in accordance with the ANS 16.1 procedure. This static, deionized water test examined the leach rate of contaminants from radioactively spiked (Cs-137) samples of each waste type. The data obtained from this method were used to generate from diffusion calculations a parameter called a leachability index (L) which is related to the leaching characteristics of the solidified waste. All waste forms exceeded an L value of 6, which is the minimum suggested by the NRC “Branch Technical Position on Waste Form” for the disposal of Class B and Class C radioactive wastes.
Stability of NZP Waste Forms and their Application To ICCP Waste
Authors: Scheetz B. E. , Komarneni S. , Fajun W. , Yang L. J. , Ollinen M. , Roy R. 
Published: March 2011

AbstractThe crystal structure of NaZr2(PO4)3, (NZP), contains three distinct crystallographic sites which between them can readily accommodate the majority of elements that are present in high level nuclear waste. The applicability of this host phase to the immobilization of mixed zirconia/alumina waste from the Idaho Chemical Processing Plant (ICPP) was demonstrated. A waste form consisting of CaF2, a number of NZP phases and F-apatite was prepared and the results of leach testing reported. Detailed stability studies of the host sodium zirconium phosphate phase were also conducted as a function of temperature, pH and time.
Tuff-Cement or Concrete Interactions in the Repository Environment
Authors: Komarneni Sridhar , Roy Della M. , Kumar Amitabha 
Published: March 2011

AbstractHydrothermal interactions of tuff or tuff minerals with cement or concrete were investigated at 200 0C under a confining pressure of 8 or 30 MPa for I to 20 weeks. These chemical interactions produced crystalline hydrous calcium silicates such as Al-substituted tobermorite, xonotlite and gyrolite. Tobermorite was the most common interaction product of cement and tuff or tuff minerals because of pozzolanic reaction. The extent of cement hydration and the quantity of cement in the cement mix affected the abundance of tobermorite as expected. The reaction of concrete with tuff resulted in the formation of smectite in addition to tobermorite due to the generation of slight acidic conditions in this reaction mixture under the present hydrothermal conditions. The formation of tobermorite by the interaction of tuff with cement or concrete has positive implications to the physical (bonding) and chemical (sorption) properties in the repository sealing system because tobermorite (Al-substituted) acts both as a binding agent and as a cation exchanger.
Geochemical Performance Evaluation and Characterization of a Potential Cementitious Repository Sealing Material for Application in the Topopah Spring Tuff Nnwsi Investigations
Authors: Scheetz Barry E. , Roy Della M. 
Published: March 2011

AbstractPreliminary geochemical evaluations of some portland cement based materials have been made in Nevada Nuclear Waste Storage Investigations (NNWSI), for possible nuclear waste repository sealing applications in welded tuff focused in the Yucca Mountain area. Portland cement based sealing materials have been evaluated in the NNWSI for possible sealing applications in a nuclear waste repository in the Topopah Spring tuff member. Cementitious sealing materials developed for long-term stability should be as nearly as possible in thermodynamic equilibrium with the host rock, or any disequilibrium should not have negative impact upon the integrity of the host rock. A primary step in achieving this equilibrium condition is to minimize the chemical potential between the sealant and the host rock. Two different approaches were evaluated to achieve this compatibility. The one approach utilized indigenous materials for the formulation of the concrete and the other utilized reactive admixtures to adjust the bulk chemical composition of the concrete formulation to approximate the local rock bulk chemistry. Testing of both formulations at conditions that represented the maximum credible temperature and pressure conditions of a repository were completed and show that the use of an indigenous tuff in the formulation without adjusting the matrix chemistry caused alterations which might compromise the performance of the concrete. In contrast, the chemically adjusted cementitious formulation exhibited minimal alteration in the J-13 groundwater of the designed test.
Heavy Phosphorus Implantation of Ge0.83Si0.17 Epitaxial Layers
Authors: Bean J.C. , Fiory A.T. , Hopkins L.C. 
Published: March 2011

ABSTRACTEpitaxial Ge-Si alloy films were grown on Si(100) by molecular beam epitaxy, subsequently given a shallow P implant, and subjected to rapid thermal processing. Heat treatment causes solid-phase epitaxial regrowth of the amorphized implanted layer similar to the case of pure Ge. Phosphorus redistribution, loss, and trapping at the Ge-Si/Si interface are also observed. Anomalous electrical activation is observed for P concentrations below 1 at.%, where the-carriers are either trapped or compensated at room temperature, but not below 100K. Analyses were carried out by Rutherford backscattering and channeling, secondary ion mass spectrometry, and temperature-dependent electrical transport.
Positive-Tone Polymer Images by Surface Modification in Ion Beam Exposures
Authors: Hiraoka Hiroyuki 
Published: March 2011

ABSTRACTUnder exposures of high energy radiation in vacuum, decarboxylation takes place efficiently on polymer surfaces having carboxylic acid groups. Low energy electron and ion beams are particularly efficient in these chemical reactions on the surfaces because their energy deposition is limited to very shallow depths. The surface areas exposed to the radiation have properties similar to hydrocarbons after decarboxylation, resulting in non-reactions in gas phase silylation, while unexposed areas undergo silylation readily due to the presence of reactive acid groups. The non-silylated areas etch faster in oxygen reactive ion etchings, giving rise to positive tone polymer images. Polymers like poly(methacrylic acid), poly(acrylic acid), and their copolymers have been used. Other polymers like poly(styrene), poly(chloromethylstyrene), and Novolac resins can also be used, because these polymers readily undergo photo-oxidation under uv-irradiation in air, generating carboxylic acid groups on their surfaces.
Outgassing of Photoresist During Ion Implantation
Authors: Roche D. , Michaud J.F. , Bruel M. 
Published: March 2011

ABSTRACTOutgassing of HUNT HPR 204 photoresist during ion implantation has been characterized by means of quadrupole mass analysis. The influence of the various parameters (implantation eneray, beam current, ion species) has been studied in order to point out the evolutions, in terms of time or implanted dose, of the target chamber pressure and the peaks at masses 26 and 28, characteristic of the photoresist outqassing. The pressure integral in the target chamber which is easily related to the integrated outgassing flux, has been found essentially dependent on the total energy deposited in the photoresist layer and on the ion penetration depth.
A Study of Ion Beam Induced Adhesion Effects in Some Metal/Insulator Systems
Authors: Sood D. K. , Skinner W. M. , Gazecki J. , Williams J. S. , Baglin J. E. E. 
Published: March 2011

ABSTRACTCooper and platinum films were deposited by evaporation and sputtering techniques onto prepared substrates of alumina, sapphire (cut along an a or c axis) and yttria stabilized zirconia. The films are then bombarded with ions of H, He, Ne and Kr at energies within and outside the ion beam mixing regime. Ion beam induced modification in adhesion and its thermal stability were measured by three techniques - a scratch test, a pull test and a peel test. Adhesive energies of these solid-solid systems were determined by contact angle measurements using scanning electron microscopy. The resistance of the films to chemical attack is modified by ion bombardment and will be shown to correlate with adhesion alterations.
Buried SiC Layers in (100) Bulk Silicon and Silicon-on-Sapphire Produced by Carbon Ion Implantation
Authors: Kroko L. , Golecki I. , GLASS H.L. 
Published: March 2011

ABSTRACTWe demonstrate the formation of buried layers of SiC in (100) single-crystal bulk Si and silicon-on-sapphire by ion implantation of 125-180 keV, (0.56-1.00)×1018 C/cm2 at 30-40 μA/cm2 into samples held at 450-650¼C. The as-implanted and 950°C annealed samples are characterized by differential infra-red absorbance and reflectance, Rutherford backscattering and channeling spectrometry, X-ray diffraction, four-point probe, Dektak profilometry, I-V measurements, spreading resistance and secondary ion mass spectrometry.