Download or read book Towards Increased Waste Loading in High Level Waste Glasses written by and published by . This book was released on 2014 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: A number of waste components in US defense high level radioactive wastes (HLW) have proven challenging for current Joule heated ceramic melter (JCHM) operations and have limited the ability to increase waste loadings beyond already realized levels. Many of these ''troublesome'' waste species cause crystallization in the glass melt that can negatively impact product quality or have a deleterious effect on melter processing. Recent efforts at US Department of Energy laboratories have focused on understanding crystallization behavior within HLW glass melts and investigating approaches to mitigate the impacts of crystallization so that increases in waste loading can be realized. Advanced glass formulations have been developed to highlight the unique benefits of next-generation melter technologies such as the Cold Crucible Induction Melter (CCIM). Crystal-tolerant HLW glasses have been investigated to allow sparingly soluble components such as chromium to crystallize in the melter but pass out of the melter before accumulating. The Hanford site AZ-101 tank waste composition represents a waste group that is waste loading limited primarily due to high concentrations of Fe2O3 (with higher Al2O3). Systematic glass formulation development utilizing slightly higher process temperatures and higher tolerance to spinel crystals demonstrated that an increase in waste loading of more than 20% could be achieved for this waste composition, and by extension higher loadings for wastes in the same group.

Download or read book Road Map for Development of Crystal Tolerant High Level Waste Glasses written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The U.S. Department of Energy (DOE) is building a Tank Waste Treatment and Immobilization Plant (WTP) at the Hanford Site in Washington to remediate 55 million gallons of radioactive waste that is being temporarily stored in 177 underground tanks. Efforts are being made to increase the loading of Hanford tank wastes in glass while meeting melter lifetime expectancies and process, regulatory, and product quality requirements. This road map guides the research and development for formulation and processing of crystaltolerant glasses, identifying near- and long-term activities that need to be completed over the period from 2014 to 2019. The primary objective is to maximize waste loading for Hanford waste glasses without jeopardizing melter operation by crystal accumulation in the melter or melter discharge riser. The potential applicability to the Savannah River Site (SRS) Defense Waste Processing Facility (DWPF) will also be addressed in this road map. The planned research described in this road map is motivated by the potential for substantial economic benefits (significant reductions in glass volumes) that will be realized if the current constraints (T1% for WTP and TL for DWPF) are approached in an appropriate and technically defensible manner for defense waste and current melter designs. The basis of this alternative approach is an empirical model predicting the crystal accumulation in the WTP glass discharge riser and melter bottom as a function of glass composition, time, and temperature. When coupled with an associated operating limit (e.g., the maximum tolerable thickness of an accumulated layer of crystals), this model could then be integrated into the process control algorithms to formulate crystal-tolerant high-level waste (HLW) glasses targeting high waste loadings while still meeting process related limits and melter lifetime expectancies. The modeling effort will be an iterative process, where model form and a broader range of conditions, e.g., glass composition and temperature, will evolve as additional data on crystal accumulation are gathered. Model validation steps will be included to guide the development process and ensure the value of the effort (i.e., increased waste loading and waste throughput). A summary of the stages of the road map for developing the crystal-tolerant glass approach, their estimated durations, and deliverables is provided.

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 An Introduction to Nuclear Waste Immobilisation written by Michael I. Ojovan and published by Elsevier. This book was released on 2010-07-07 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: Safety and environmental impact is of uppermost concern when dealing with the movement and storage of nuclear waste. The 20 chapters in 'An Introduction to Nuclear Waste Immobilisation' cover all important aspects of immobilisation, from nuclear decay, to regulations, to new technologies and methods. Significant focus is given to the analysis of the various matrices used in transport: cement, bitumen and glass, with the greatest attention being given to glass. The last chapter concentrates on the performance assessment of each matrix, and on new developments of ceramics and glass composite materials, thermochemical methods and in-situ metal matrix immobilisation. The book thoroughly covers all issues surrounding nuclear waste: from where to locate nuclear waste in the environment, through nuclear waste generation and sources, treatment schemes and technologies, immobilisation technologies and waste forms, disposal and long term behaviour. Particular attention is paid to internationally approved and worldwide-applied approaches and technologies. * Each chapter focuses on a different matrix used in nuclear waste immobilisation: Cement, bitumen, glass and new materials. * Keeps the most important issues surrounding nuclear waste – such as treatment schemes and technologies, and disposal - at the forefront.

Download or read book Cementitious Materials for Nuclear Waste Immobilization written by Rehab O. Abdel Rahman and published by John Wiley & Sons. This book was released on 2014-11-17 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cementitious materials are an essential part in any radioactive waste disposal facility. Conditioning processes such as cementation are used to convert waste into a stable solid form that is insoluble and will prevent dispersion to the surrounding environment. It is incredibly important to understand the long-term behavior of these materials. This book summarises approaches and current practices in use of cementitious materials for nuclear waste immobilisation. It gives a unique description of the most important aspects of cements as nuclear waste forms: starting with a description of wastes, analyzing the cementitious systems used for immobilization and describing the technologies used, and ending with analysis of cementitious waste forms and their long term behavior in an envisaged disposal environment. Extensive research has been devoted to study the feasibility of using cement or cement based materials in immobilizing and solidifying different radioactive wastes. However, these research results are scattered. This work provides the reader with both the science and technology of the immobilization process, and the cementitious materials used to immobilize nuclear waste. It summarizes current knowledge in the field, and highlights important areas that need more investigation. The chapters include: Introduction, Portland cement, Alternative cements, Cement characterization and testing, Radioactive waste cementation, Waste cementation technology, Cementitious wasteform durability and performance assessment.

Download or read book Research Needs for High Level Waste Stored in Tanks and Bins at U S Department of Energy Sites written by National Research Council and published by National Academies Press. This book was released on 2001-10-05 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: The United States Department of Energy (DOE) has approximately 400 million liters (100 million gallons) of liquid high-level waste (HLW) stored in underground tanks and approximately 4,000 cubic meters of solid HLW stored in bins. The current DOE estimate of the cost of converting these liquid and solid wastes into stable forms for shipment to a geological repository exceeds $50 billion to be spent over several decades (DOE, 2000). The Committee on Long-Term Research Needs for Radioactive High-Level Waste at Department of Energy Sites was appointed by the National Research Council (NRC) to advise the Environmental Management Science Program (EMSP) on a long-term research agenda addressing the above problems related to HLW stored in tanks and bins at DOE sites.

Download or read book Radioactive Waste Forms for the Future written by Werner Lutze and published by North Holland. This book was released on 1988 with total page 802 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents a compilation of important information on the full range of radioactive waste forms that have been developed, or at least suggested, for the incorporation of high-level nuclear waste. Many of the results were published in the ''gray literature'' of final reports of national laboratories or in various, generally less available, proceedings volumes. This is the first publication to draw information on nuclear waste forms for high-level wastes together into a single volume. Although borosilicate glass has become the standard waste form, additional research in this compound is still necessary. With improved technology (particularly processing technologies) and with a more detailed knowledge of repository conditions, glasses and second generation waste forms with improved performance properties can be developed. Sustained research programs on nuclear waste form development will yield results that can only add to public confidence and the final, safe disposal of nuclear waste. The aim of this volume is to provide a 'spring board' for these future research efforts. A detailed presentation is given on the properties and performance of non-crystalline waste forms (borosilicate glass, sintered glass, and lead-iron phosphate glass), and crystalline waste forms (Synroc, tailored ceramics, TiO 2 - ceramic matrix, glass-ceramics and FUETAP concrete). A chapter on Novel Waste Forms reviews a number of methods that warrant further development because of their potential superior performance and unique applications. The final chapter includes a tabulated comparison of important waste form properties and an extended discussion on the corrosion process and radiation damage effects for each waste form. Of particular interest is a performance assessment of nuclear waste borosilicate glass and the crystalline ceramic Synroc. This is the first detailed attempt to compare these two important waste forms on the basis of their materials properties. The discussion emphasizes the difficulties in making such a comparison and details the types of data that are required. Each chapter has been written by an expert and includes a current compilation of waste form properties with an extensive list of references. This volume will provide a stimulus for future research as well as useful reference material for scientists working in the field of nuclear waste disposal and materials science.

Download or read book Chemical Analysis of Simulated High Level Waste Glasses to Support Stage III Sulfate Solubility Modeling written by and published by . This book was released on 2016 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The U.S. Department of Energy (DOE), Office of Environmental Management (EM) is sponsoring an international, collaborative project to develop a fundamental model for sulfate solubility in nuclear waste glass. The solubility of sulfate has a significant impact on the achievable waste loading for nuclear waste forms within the DOE complex. These wastes can contain relatively high concentrations of sulfate, which has low solubility in borosilicate glass. 1 This is a significant issue for low activity waste (LAW) glass and is projected to have a major impact on the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Sulfate solubility has also been a limiting factor for recent high level waste (HLW) sludge processed at the Savannah River Site (SRS) Defense Waste Processing Facility (DWPF).2-5 The low solubility of sulfate in glass, along with melter and off-gas corrosion constraints, dictate that the waste be blended with lower sulfate concentration waste sources or washed to remove sulfate prior to vitrification. The development of enhanced borosilicate glass compositions with improved sulfate solubility will allow for higher waste loadings and accelerate mission completion. The objective of the current scope being pursued by SHU is to mature the sulfate solubility model to the point where it can be used to guide glass composition development for DWPF and WTP, allowing for enhanced waste loadings and waste throughput at these facilities. A series of targeted glass compositions was selected to resolve data gaps in the model and is identified as Stage III. 10 SHU fabricated these glasses and sent samples to SRNL for chemical composition analysis. SHU will use the resulting data to enhance the sulfate solubility model and resolve any deficiencies. In this report, SRNL provides chemical analyses for the Stage III, simulated HLW glasses fabricated by SHU in support of the sulfate solubility model development.

Download or read book The Storage and Disposal of Radioactive Waste as Glass in Canisters written by J. E. Mendel and published by . This book was released on 1978 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Towards Optimization of Nuclear Waste Glass written by and published by . This book was released on 1994 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vitrification of both low- and high-level wastes from 177 tanks at Hanford poses a great challenge to glass makers, whose task is to formulate a system of glasses that are acceptable to the federal repository for disposal. The enormous quantity of the waste requires a glass product of the lowest possible volume. The incomplete knowledge of waste composition, its variability, and lack of an appropriate vitrification technology further complicates this difficult task. A simple relationship between the waste loading and the waste glass volume is presented and applied to the predominantly refractory (usually high-activity) and predominantly alkaline (usually low-activity) waste types. Three factors that limit waste loading are discussed, namely product acceptability, melter processing, and model validity. Glass formulation and optimization problems are identified and a broader approach to uncertainties is suggested.

Download or read book A Review of Department of Energy s Radioactive High level Waste Cleanup Programs written by United States. Congress. House. Committee on Energy and Commerce. Subcommittee on Oversight and Investigations and published by . This book was released on 2003 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optimization of High level Waste Loading in a Borosilicate Glass Matrix by Using Chemical Durability Modeling Approach written by Javeed Mohammad and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A laboratory scale study was carried out on a set of 6 borosilicate waste glasses made from simulated high-level nuclear waste. The test matrix was designed to explore the composition region suitable for the long-term geologic disposal of high-temperature-and high-waste-containing glasses. The glass compositions were selected to achieve maximum waste loading without a sacrifice in glass durability. The relationship between glass composition and chemical durability was examined. The qualitative effect of increasing B2O3 content on the overall waste glass leaching behavior has also been addressed. The glass composition matrix was designed by systematically varying the factors: %waste loading and (SiO2+Frit):B2O3 ratio, with (SiO2:Frit) ratio being held constant. In order to assess the chemical durability, the Product Consistency Test (ASTM C-1285) was performed. Under PCT protocol, crushed glass was allowed to react with ASTM type I water under static conditions. All leachate solutions were analyzed by the technique; Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). A statistical regression technique was utilized to model the normalized release of the major soluble elements, Na, Si, and B, as a function of the individual as well as interactive chemical effects (B2O3, Al2O3, Fe2O3, MnO, SiO2, SrO, Na2O, B2O3*SiO2, B2O3*Al2O3, Fe2O3*Na2O, Al2O3*Na2O, and MnO*SiO2). Geochemical modeling was performed using the computer code EQ3/6 to: (1) determine the saturation states of the possible silicate minerals, a-cristobalite and chalcedony; and (2) predict the most stable mineral phase based on the mineral thermodynamic data. Mineral/water interactions were analyzed by representing the resultant glass data on a Na-Al-Si-O-H stability diagram.

Download or read book Advanced High Level Waste Glass Research and Development Plan written by and published by . This book was released on 2015 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The U.S. Department of Energy Office of River Protection (ORP) has implemented an integrated program to increase the loading of Hanford tank wastes in glass while meeting melter lifetime expectancies and process, regulatory, and product quality requirements. The integrated ORP program is focused on providing a technical, science-based foundation from which key decisions can be made regarding the successful operation of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) facilities. The fundamental data stemming from this program will support development of advanced glass formulations, key process control models, and tactical processing strategies to ensure safe and successful operations for both the low-activity waste (LAW) and high-level waste (HLW) vitrification facilities with an appreciation toward reducing overall mission life. The purpose of this advanced HLW glass research and development plan is to identify the near-, mid-, and longer-term research and development activities required to develop and validate advanced HLW glasses and their associated models to support facility operations at WTP, including both direct feed and full pretreatment flowsheets. This plan also integrates technical support of facility operations and waste qualification activities to show the interdependence of these activities with the advanced waste glass (AWG) program to support the full WTP mission. Figure ES-1 shows these key ORP programmatic activities and their interfaces with both WTP facility operations and qualification needs. The plan is a living document that will be updated to reflect key advancements and mission strategy changes. The research outlined here is motivated by the potential for substantial economic benefits (e.g., significant increases in waste throughput and reductions in glass volumes) that will be realized when advancements in glass formulation continue and models supporting facility operations are implemented. Developing and applying advanced glass formulations will reduce the cost of Hanford tank waste management by reducing the schedule for tank waste treatment and reducing the amount of HLW glass for storage, transportation, and disposal. Additional benefits will be realized if advanced glasses are developed that demonstrate more tolerance for key components in the waste (such as Al2O3, Cr2O3, SO3 and Na2O) above the currently defined WTP constraints. Tolerating these higher concentrations of key waste loading limiters may reduce the burden on (or even eliminate the need for) leaching to remove Cr and Al and washing to remove excess S and Na from the HLW fraction. Advanced glass formulations may also make direct vitrification of the HLW fraction without significant pretreatment more cost effective. Finally, the advanced glass formulation efforts seek not only to increase waste loading in glass, but also to increase glass production rate. When coupled with higher waste loading, ensuring that all of the advanced glass formulations are processable at or above the current contract processing rate leads to significant improvements in waste throughput (the amount of waste being processed per unit time), which could significantly reduce the overall WTP mission life. The integration of increased waste loading, reduced leaching/washing requirements, and improved melting rates provides a system-wide approach to improve the effectiveness of the WTP process.

Download or read book Savannah River Plant High Level Waste Waste Form Selection Aiken written by and published by . This book was released on 1982 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 OPTIMIZATION OF HIGH LEVEL WASTE LOADING IN A BOROSILICATE GLASS MATRIX BY USING CHEMICAL DURABILITY MODELING APPROACH written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A laboratory scale study was carried out on a set of 6 borosilicate waste glasses made from simulated high-level nuclear waste. The test matrix was designed to explore the composition region suitable for the long-term geologic disposal of high-temperature-and high-waste-containing glasses. The glass compositions were selected to achieve maximum waste loading without a sacrifice in glass durability. The relationship between glass composition and chemical durability was examined. The qualitative effect of increasing B2O3 content on the overall waste glass leaching behavior has also been addressed. The glass composition matrix was designed by systematically varying the factors: %waste loading and (SiO2+Frit):B2O3 ratio, with (SiO2:Frit) ratio being held constant. In order to assess the chemical durability, the Product Consistency Test (ASTM C-1285) was performed. Under PCT protocol, crushed glass was allowed to react with ASTM type I water under static conditions. All leachate solutions were analyzed by the technique; Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). A statistical regression technique was utilized to model the normalized release of the major soluble elements, Na, Si, and B, as a function of the individual as well as interactive chemical effects (B2O3, Al2O3, Fe2O3, MnO, SiO2, SrO, Na2O, B2O3*SiO2, B2O3*Al2O3, Fe2O3*Na2O, Al2O3*Na2O, and MnO*SiO2). Geochemical modeling was performed using the computer code EQ3/6 to: (1) determine the saturation states of the possible silicate minerals, a-cristobalite and chalcedony; and (2) predict the most stable mineral phase based on the mineral thermodynamic data. Mineral/water interactions were analyzed by representing the resultant glass data on a Na-Al-Si-O-H stability diagram.

Download or read book Radioactive Waste Management written by and published by . This book was released on 1981 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: