Download or read book A Critical Evaluation of the Dissolution Mechanisms of High level Waste Glasses in Conditions of Relevance for Geological Disposal GLAMOR written by and published by . This book was released on 2008 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Different theories have been proposed worldwide in the past for interpreting the results from experimental programmes on the dissolution of nuclear waste glasses. The common and important trend is that the dissolution rate of nuclear waste glass decreases with increasing time of exposure to the contacting solution under static conditions. The interpretations are diverging in that the decrease may be attributed to saturation effects in the solution, to protecting effects of the reaction layer formed on the glass surface, or to ion exchange processes between solution and glass. Currently these different interpretations relate to either a thermodynamically (affinity) or with kinetically controlled dissolution behaviour. The first objective of the GLAMOR1 project was to achieve a common understanding amongst the participants on the interpretation of the decrease in dissolution rate of nuclear waste glasses as observed in most experimental programmes and referring to geological disposal conditions. The project started from a selection of existing experimental data and existing analytical models as the basis of its work. A group of acknowledged international experts identified the experimental data to be used in the project and applied the models to the data. The experimental data were produced by various laboratories and under various experimental conditions (i.e. different glass compositions, pure solutions, solutions loaded with solids referring to disposal concepts). The second objective of the project was to better define and quantify the uncertainties associated with the calculations performed in modelling, for instance the uncertainty of the parameters used in the models. This modelling was done so that laboratory data would be properly interpreted and correctly extrapolated beyond the laboratory time scale of several years. As a result of this project we achieved a common view of the different glass dissolution processes, and the different individual views on certain processes were integrated into an overall picture characterised by the following observations: - Glass dissolution is strongly linked to the concentration of dissolved silica and as much as 10 000 times lower long-term dissolution rates relative to the initial dissolution rate can be achieved when Si concentrations are high. - The principal source of high Si concentration is the glass itself. As long as the silica from the glass is not consumed by reaction with near-field materials, high silica concentrations in solution are expected to be achieved in a few months, and correspondingly low glass dissolution rates. Even though there is a general agreement on these observations and on their mathematical treatment in conceptual models, there is still large uncertainty on how to interpret in detail the mechanism by which high silica concentrations slow down the dissolution rates. Two key interpretations were evaluated in detail in the project: (1) affinity-limited dissolution and (2) rate decrease by transport limitation through the reaction layer. We conclude that both affect the rate decrease. By applying the analytical models we realised a better understanding of the role of the different parameters considered in the models and of the impact of the uncertainties of these parameters. We were however unable to quantify the uncertainties associated with the calculations performed in modelling because of the large uncertainties on some of the modelling parameters still existing. The following report provides a summary involving detailed discussions of the two main models and their potential use to explain the long-term behaviour of nuclear waste glasses under conditions relevant for geological disposal conditions.
Download or read book Environmental Issues and Waste Management Technologies in the Materials and Nuclear Industries XII written by Alex Cozzi and published by John Wiley & Sons. This book was released on 2009-09-24 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book documents a special collection of articles from a select group of invited prominent scientists from academia, national laboratories and industry who presented their work at the symposia on Environmental and Energy Issues at the 2008 Materials Science and Technology (MS&T’08) conference held in Pittsburgh, PA. These articles represent a summary of the presentations focusing on topics in nuclear, environmental, and green engineering were held, including a discussion of Waste Glass Leach Testing and Modeling.
Download or read book Radionuclide Source Term for HLW Glass Spent Nuclear Fuel and Compacted Hulls and End Pieces CSD C Waste written by Kienzler, Bernhard and published by KIT Scientific Publishing. This book was released on 2012-09-28 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Materials for Nuclear Waste Immobilization written by Michael I. Ojovan and published by MDPI. This book was released on 2020-01-09 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book outlines recent advances in nuclear wasteform materials including glasses, ceramics and cements and spent nuclear fuel. It focuses on durability aspects and contains data on performance of nuclear wasteforms as well as expected behavior in a disposal environment.
Download or read book Waste Forms Technology and Performance written by National Research Council and published by National Academies Press. This book was released on 2011-08-05 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Department of Energy's Office of Environmental Management (DOE-EM) is responsible for cleaning up radioactive waste and environmental contamination resulting from five decades of nuclear weapons production and testing. A major focus of this program involves the retrieval, processing, and immobilization of waste into stable, solid waste forms for disposal. Waste Forms Technology and Performance, a report requested by DOE-EM, examines requirements for waste form technology and performance in the cleanup program. The report provides information to DOE-EM to support improvements in methods for processing waste and selecting and fabricating waste forms. Waste Forms Technology and Performance places particular emphasis on processing technologies for high-level radioactive waste, DOE's most expensive and arguably most difficult cleanup challenge. The report's key messages are presented in ten findings and one recommendation.
Download or read book The Chemistry of the Actinide and Transactinide Elements Set Vol 1 6 written by L.R. Morss and published by Springer Science & Business Media. This book was released on 2010-10-21 with total page 4511 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fourth edition of "The Chemistry of the Actinide and Transactinide Elements" comprises all chapters in volumes 1 through 5 of the third edition (published in 2006) plus a new volume 6. To remain consistent with the plan of the first edition, “ ... to provide a comprehensive and uniform treatment of the chemistry of the actinide [and transactinide] elements for both the nuclear technologist and the inorganic and physical chemist,” and to be consistent with the maturity of the field, the fourth edition is organized in three parts. The first group of chapters follows the format of the first and second editions with chapters on individual elements or groups of elements that describe and interpret their chemical properties. A chapter on the chemical properties of the transactinide elements follows. The second group, chapters 15-26, summarizes and correlates physical and chemical properties that are in general unique to the actinide elements, because most of these elements contain partially-filled shells of 5f electrons whether present as isolated atoms or ions, as metals, as compounds, or as ions in solution. The third group, chapters 27-39, focuses on specialized topics that encompass contemporary fields related to actinides in the environment, in the human body, and in storage or wastes. Two appendices at the end of volume 5 tabulate important nuclear properties of all actinide and transactinide isotopes. Volume 6 (Chapters 32 through 39) consists of new chapters that focus on actinide species in the environment, actinide waste forms, nuclear fuels, analytical chemistry of plutonium, actinide chalcogenide and hydrothermal synthesis of actinide compounds. The subject and author indices and list of contributors encompass all six volumes.
Download or read book Advances in Transport Phenomena written by Liqiu Wang and published by Springer Science & Business Media. This book was released on 2009-10-15 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: The term transport phenomena is used to describe processes in which mass, momentum, energy and entropy move about in matter. Advances in Transport Phenomena provide state-of-the-art expositions of major advances by theoretical, numerical and experimental studies from a molecular, microscopic, mesoscopic, macroscopic or megascopic point of view across the spectrum of transport p- nomena, from scientific enquiries to practical applications. The annual review series intends to fill the information gap between regularly published journals and university-level textbooks by providing in-depth review articles over a broader scope than in journals. The authoritative articles, contributed by international- leading scientists and practitioners, establish the state of the art, disseminate the latest research discoveries, serve as a central source of reference for fundamentals and applications of transport phenomena, and provide potential textbooks to senior undergraduate and graduate students. The series covers mass transfer, fluid mechanics, heat transfer and thermo- namics. The 2009 volume contains the four articles on biomedical, environmental and nanoscale transports. The editorial board expresses its appreciation to the c- tributing authors and reviewers who have maintained the standard associated with Advances in Transport Phenomena. We also would like to acknowledge the efforts of the staff at Springer who have made the professional and attractive pr- entation of the volume. Serial Editorial Board Editor-in-Chief Professor L. Q. Wang The University of Hong Kong, Hong Kong; lqwang@hku. hk Editors Professor A. R. Balakrishnan Indian Institute of Technology Madras, India Professor A.
Download or read book Fundamentals of Materials for Energy and Environmental Sustainability written by David S. Ginley and published by Cambridge University Press. This book was released on 2011-11-30 with total page 773 pages. Available in PDF, EPUB and Kindle. Book excerpt: How will we meet rising energy demands? What are our options? Are there viable long-term solutions for the future? Learn the fundamental physical, chemical and materials science at the heart of renewable/non-renewable energy sources, future transportation systems, energy efficiency and energy storage. Whether you are a student taking an energy course or a newcomer to the field, this textbook will help you understand critical relationships between the environment, energy and sustainability. Leading experts provide comprehensive coverage of each topic, bringing together diverse subject matter by integrating theory with engaging insights. Each chapter includes helpful features to aid understanding, including a historical overview to provide context, suggested further reading and questions for discussion. Every subject is beautifully illustrated and brought to life with full color images and color-coded sections for easy browsing, making this a complete educational package. Fundamentals of Materials for Energy and Environmental Sustainability will enable today's scientists and educate future generations.
Download or read book Handbook of Nuclear Engineering written by Dan Gabriel Cacuci and published by Springer Science & Business Media. This book was released on 2010-09-14 with total page 3701 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is an authoritative compilation of information regarding methods and data used in all phases of nuclear engineering. Addressing nuclear engineers and scientists at all levels, this book provides a condensed reference on nuclear engineering since 1958.
Download or read book Symposium written by Pierre van Iseghem and published by . This book was released on 2006 with total page 1122 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Defense High Level Waste Glass Degradation written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this Analysis/Model Report (AMR) is to document the analyses that were done to develop models for radionuclide release from high-level waste (HLW) glass dissolution that can be integrated into performance assessment (PA) calculations conducted to support site recommendation and license application for the Yucca Mountain site. This report was developed in accordance with the ''Technical Work Plan for Waste Form Degradation Process Model Report for SR'' (CRWMS M & O 2000a). It specifically addresses the item, ''Defense High Level Waste Glass Degradation'', of the product technical work plan. The AP-3.15Q Attachment 1 screening criteria determines the importance for its intended use of the HLW glass model derived herein to be in the category ''Other Factors for the Postclosure Safety Case-Waste Form Performance'', and thus indicates that this factor does not contribute significantly to the postclosure safety strategy. Because the release of radionuclides from the glass will depend on the prior dissolution of the glass, the dissolution rate of the glass imposes an upper bound on the radionuclide release rate. The approach taken to provide a bound for the radionuclide release is to develop models that can be used to calculate the dissolution rate of waste glass when contacted by water in the disposal site. The release rate of a particular radionuclide can then be calculated by multiplying the glass dissolution rate by the mass fraction of that radionuclide in the glass and by the surface area of glass contacted by water. The scope includes consideration of the three modes by which water may contact waste glass in the disposal system: contact by humid air, dripping water, and immersion. The models for glass dissolution under these contact modes are all based on the rate expression for aqueous dissolution of borosilicate glasses. The mechanism and rate expression for aqueous dissolution are adequately understood; the analyses in this AMR were conducted to provide models and parameter values that can be used to calculate the dissolution rates for the different modes of water contact. The analyses were conducted to identify key aspects of the mechanistic model for glass dissolution to be included in the abstracted models used for PA calculations, evaluate how the models can be used to calculate bounding values of the glass dissolution rates under anticipated water contact modes in the disposal. system, and determine model parameter values for the range of potential waste glass compositions and anticipated environmental conditions. The analysis of a bounding rate also considered the effects of the buildup of glass corrosion products in the solution contacting the glass and potential effects of alteration phase formation. Note that application of the models and model parameter values is constrained to the anticipated range of HLW glass compositions and environmental conditions. The effects of processes inherent to exposure to humid air and dripping water were not modeled explicitly. Instead, the impacts of these processes on the degradation rate were taken into account by using empirically measured parameter values. These include the rates at which water sorbs onto the glass, drips onto the glass, and drips off of the glass. The dissolution rates of glasses that were exposed to humid air and dripping water measured in laboratory tests are used to estimate model parameter values for contact by humid air and dripping water in the disposal system.
Download or read book Structure and Durability of UK Simulated High Level Nuclear Waste Glasses written by Nathan Cassingham and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The understanding of dissolution of the British nuclear waste glass, as compared to other nuclear waste glasses, is limited. The few studies that have been performed were generally done in static leach tests with the exception of the single pass flow through test performed by Abratis during his PhD, producing a number of papers (Abraitis, P.K., Univ. Manchester, 1999; Abraitis, P.K. et. al., Applied Geochemistry 15 (2000) 1399; Abraitis, P.K. et. al., Mat. Res. Soc. Sym. Pro. 556 (1999) 401). In order to gain further insight to the British nuclear waste glasses X-ray absorption spectroscopy was used along with dissolution studies of British simulated nuclear waste glasses to determine the role of Zn and to ascertain the mechanisms of corrosion. Both baseline glasses along with a Blend simulated nuclear waste glass were studied to give better comparisons with previous results by other authors. The Blend waste glass is composed of a mixture of Magnox reactor waste and thorium oxide reprocessing (ThORP) waste at a wt% of 25wt% Magnox waste and 75 wt% ThORP. Zn K edge X-ray absorption spectroscopy was applied to determine the Zn coordination environment in model inactive UK high level waste (HLW) glasses. Quantitative analysis of the X-ray absorption fine structure (EXAFS) data provided conclusive evidence for the presence of ZnO4 species participating in network formation, linking, on average, to 2 ± 1 SiO4 units via bridging oxygen atoms. Excellent quantitative agreement was observed between the Zn-O contact distance and coordination number determined from EXAFS and previous Molecular Dynamics simulations of glasses with the same nominal composition. Analysis also provided evidence in support of the network forming role of Zn as predicted from Molecular Dynamics simulation, but it was not possible to confirm the predicted clustering of Zn species at high Zn concentration in simple soda lime silica glasses. The single pass flow through (SPFT) work in this study has shown that the steady state dissolution of a base glass with 25 wt% waste loading (MW+25wt%) and a base glass with 30 wt% waste loading (MW+30wt%) of Blend simulated nuclear waste glasses is similar to that of previous studies. The SPFT flow per surface area (Q/S) results are consistent with previous studies. The dissolution rate dependency on temperature and pH of was also consistent with similar glasses. The NRi with respect to B, Si, Na and Al, of the glasses in this study increased with an increase in solution pH. The average activation energy with respect to Si was consistent for a surface controlled reaction with these glasses as was shown in previous studies on MW+Magnox, a similar glass. One of the current designs for a geological repository of HLW is a co-located repository with intermediate level waste (ILW). At long times, there is the possibility of hyper alkaline solution from the ILW repository interacting with the vitrified HLW glass wasteforms. Dissolution studies were performed to understand the mechanisms by which the UK HLW glasses will corrode under hyper alkaline solutions. The addition of an alkali buffer to high purity H2O resulted in a decrease of the dissolution rate for the MW Blend glasses during the product consistency type tests. The concentration of Si in solution for all of the samples suggests that Ca and Si are co-precipitating as was evident from the decrease in Ca concentrations at short times. It is suggested that the presence of Ca in solution forms a passive reactive interface (PRI) which decreases the rate of formation of a hydrated surface layer decreasing the overall dissolution rate. The results from the geochemical modelling of the product consistency type tests showed that Ca and Si are co-precipitating at short times decreasing the normalised mass loss. This is evident from the Ca and Si phases which are most probable to precipitate out of solution as suggested by the geochemical modelling results from PhREEQC In order to understand the mechanisms of alteration layer formation of the UK HLW glasses, vapour hydration tests (VHT) were performed. Results from the time dependant VHT experiments have shown changes in the mechanisms of alteration layer formation with the addition of the simulated Blend waste to the base glasses. It was also shown that iron may be a suppressor to zinc dissolution. Both a Ca and Zn doped Blend waste glass and a base glass doped with Fe Zn and Zr did not show significant layers of zinc in the alteration layer as shown in the Ca and Zn doped base glass in both the reproducibility or time-dependant VHT experiments. Giesler et al. have similar results to the VHT results in this study, which correlate to an interface-coupled dissolution-reprecipitation mechanism when simulated Blend waste is added to the base glasses (Giesler, T. et. al., J. Non-Cryst. Solids 356 (2010) 1458). However, further.
Download or read book Glass as a Waste Form and Vitrification Technology written by National Research Council and published by National Academies Press. This book was released on 1997-03-02 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Defense HLW Glass Degradation Model written by D. Strachan and published by . This book was released on 2004 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this report is to document the development of a model for calculating the release rate for radionuclides and other key elements from high-level radioactive waste (HLW) glasses under exposure conditions relevant to the performance of the repository. Several glass compositions are planned for the repository, some of which have yet to be identified (i.e., glasses from Hanford and Idaho National Engineering and Environmental Laboratory). The mechanism for glass dissolution is the same for these glasses and the glasses yet to be developed for the disposal of DOE wastes. All of these glasses will be of a quality consistent with the glasses used to develop this report.
Download or read book High level Waste Glass Compendium what it Tells Us Concerning the Durability of Borosilicate Waste Glass written by and published by . This book was released on 1993 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Facilities for vitrification of high-level nuclear waste in the United States are scheduled for startup in the next few years. It is, therefore, appropriate to examine the current scientific basis for understanding the corrosion of high-level waste borosilicate glass for the range of service conditions to which the glass products from these facilities may be exposed. To this end, a document has been prepared which compiles worldwide information on borosilicate waste glass corrosion. Based on the content of this document, the acceptability of canistered waste glass for geological disposal is addressed. Waste glass corrosion in a geologic repository may be due to groundwater and/or water vapor contact. The important processes that determine the glass corrosion kinetics under these conditions are discussed based on experimental evidence from laboratory testing. Testing data together with understanding of the long-term corrosion kinetics are used to estimate radionuclide release rates. These rates are discussed in terms of regulatory performance standards.
Download or read book Natural Glass Analogues to Alteration of Nuclear Waste Glass written by and published by . This book was released on 1990 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this report is to review previous work on the weathering of natural glasses; and to make recommendations for further work with respect to studying the alteration of natural glasses as it relates quantifying rates of dissolution. the first task was greatly simplified by the published papers of Jercinovic and Ewing (1987) and Byers, Jercinovic, and Ewing (1987). The second task is obviously the more difficult of the two and the author makes no claim of completeness in this regard. Glasses weather in the natural environment by reacting with aqueous solutions producing a rind of secondary solid phases. It had been proposed by some workers that the thickness of this rind is a function of the age of the glass and thus could be used to estimate glass dissolution rates. However, Jercinovic and Ewing (1987) point out that in general the rind thickness does not correlate with the age of the glass owing to the differences in time of contact with the solution compared to the actual age of the sample. It should be noted that the rate of glass dissolution is also a function of the composition of both the glass and the solution, and the temperature. Quantification of the effects of these parameters (as well as time of contact with the aqueous phase and flow rates) would thus permit a prediction of the consequences of glass-fluid interactions under varying environmental conditions. Defense high- level nuclear waste (DHLW), consisting primarily of liquid and sludge, will be encapsulated by and dispersed in a borosilicate glass before permanent storage in a HLW repository. This glass containing the DHLW serves to dilute the radionuclides and to retard their dispersion into the environment. 318 refs.
Download or read book Natural Glass Analogues to Alteration of Nuclear Waste Glass written by William F. McKenzie and published by . This book was released on 1990 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this report is to review previous work on the weathering of natural glasses; and to make recommendations for further work with respect to studying the alteration of natural glasses as it relates quantifying rates of dissolution. the first task was greatly simplified by the published papers of Jercinovic and Ewing (1987) and Byers, Jercinovic, and Ewing (1987). The second task is obviously the more difficult of the two and the author makes no claim of completeness in this regard. Glasses weather in the natural environment by reacting with aqueous solutions producing a rind of secondary solid phases. It had been proposed by some workers that the thickness of this rind is a function of the age of the glass and thus could be used to estimate glass dissolution rates. However, Jercinovic and Ewing (1987) point out that in general the rind thickness does not correlate with the age of the glass owing to the differences in time of contact with the solution compared to the actual age of the sample. It should be noted that the rate of glass dissolution is also a function of the composition of both the glass and the solution, and the temperature. Quantification of the effects of these parameters (as well as time of contact with the aqueous phase and flow rates) would thus permit a prediction of the consequences of glass-fluid interactions under varying environmental conditions. Defense high- level nuclear waste (DHLW), consisting primarily of liquid and sludge, will be encapsulated by and dispersed in a borosilicate glass before permanent storage in a HLW repository. This glass containing the DHLW serves to dilute the radionuclides and to retard their dispersion into the environment. 318 refs.
