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 Development of Crystal Tolerant High Level Waste Glasses written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Twenty five glasses were formulated. They were batched from HLW AZ-101 simulant or raw chemicals and melted and tested with a series of tests to elucidate the effect of spinel-forming components (Ni, Fe, Cr, Mn, and Zn), Al, and noble metals (Rh2O3 and RuO2) on the accumulation rate of spinel crystals in the glass discharge riser of the high-level waste (HLW) melter. In addition, the processing properties of glasses, such as the viscosity and TL, were measured as a function of temperature and composition. Furthermore, the settling of spinel crystals in transparent low-viscosity fluids was studied at room temperature to access the shape factor and hindered settling coefficient of spinel crystals in the Stokes equation. The experimental results suggest that Ni is the most troublesome component of all the studied spinel-forming components producing settling layers of up to 10.5 mm in just 20 days in Ni-rich glasses if noble metals or a higher concentration of Fe was not introduced in the glass. The layer of this thickness can potentially plug the bottom of the riser, preventing glass from being discharged from the melter. The noble metals, Fe, and Al were the components that significantly slowed down or stopped the accumulation of spinel at the bottom. Particles of Rh2O3 and RuO2, hematite and nepheline, acted as nucleation sites significantly increasing the number of crystals and therefore decreasing the average crystal size. The settling rate of ≤10-?m crystal size around the settling velocity of crystals was too low to produce thick layers. The experimental data for the thickness of settled layers in the glasses prepared from AZ-101 simulant were used to build a linear empirical model that can predict crystal accumulation in the riser of the melter as a function of concentration of spinel-forming components in glass. The developed model predicts the thicknesses of accumulated layers quite well, R2 = 0.985, and can be become an efficient tool for the formulation of the crystal-tolerant HLW glasses for higher waste loading. A physical modeling effort revealed that the Stokes and Richardson-Zaki equations can be used to adequately predict the accumulation rate of spinel crystals of different sizes and concentrations in the glass discharge riser of HLW melters. The determined shape factor for the glass beads was only 0.73% lower than the theoretical shape factor for a perfect sphere. The shape factor for the spinel crystals matched the theoretically predicted value to within 10% and was smaller than that of the beads, given the larger drag force caused by the larger surface area-to-volume ratio of the octahedral crystals. In the hindered settling experiments, both the glass bead and spinel suspensions were found to follow the predictions of the Richardson-Zaki equation with the exponent n = 3.6 and 2.9 for glass beads and spinel crystals, respectively.
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 EMPIRICAL MODEL FOR FORMULATION OF CRYSTAL TOLERANT HLW GLASSES written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Historically, high-level waste (HLW) glasses have been formulated with a low liquideus temperature (T{sub L}), or temperature at which the equilibrium fraction of spinel crystals in the melt is below 1 vol % (T{sub 0.01}), nominally below 1050 C. These constraints cannot prevent the accumulation of large spinel crystals in considerably cooler regions (≈ 850 C) of the glass discharge riser during melter idling and significantly limit the waste loading, which is reflected in a high volume of waste glass, and would result in high capital, production, and disposal costs. A developed empirical model predicts crystal accumulation in the riser of the melter as a function of concentration of spinel-forming components in glass, and thereby provides guidance in formulating crystal-tolerant glasses that would allow high waste loadings by keeping the spinel crystals small and therefore suspended in the glass.
Download or read book Advances in Materials Science for Environmental and Energy Technologies IV written by Josef Matyas and published by John Wiley & Sons. This book was released on 2015-10-05 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings contains a collection of 20 papers from the following five 2014 Materials Science and Technology (MS&T'14) symposia: Materials Issues in Nuclear Waste Management in the 21st Century Green Technologies for Materials Manufacturing and Processing V Nanotechnology for Energy, Healthcare and Industry Materials for Processes for CO2 Capture, Conversion, and Sequestration Materials Development for Nuclear Applications and Extreme Environments
Download or read book HLW Glass Studies written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Materials Science for Environmental and Nuclear Technology written by Kevin M. Fox and published by John Wiley & Sons. This book was released on 2010-10-01 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Materials Science and Technology 2009 Conference and Exhibition (MS&T’09) was held October 25-29, 2009, in Pittsburgh, Pennsylvania. A major theme of the conference was Environmental and Energy Issues. Papers from three of the symposia held under that theme are included in this volume. These symposia include Materials Solutions for the Nuclear Renaissance; Green Engineering and Environmental Stewardship; and Nanotechnology for Energy. These symposia included a variety of presentations with sessions focused on sustainable energy, photovoltaics, nanowires and composites, energy harvesting, catalysts, thin films, corrosion, nuclear fuels, materials in aggressive environments, glass and ceramics for waste disposition, modeling and thermal properties, and education. Also included was a series of invited presentations and an international panel discussion on cement waste forms. The Green Engineering and Environmental Stewardship symposium was sponsored by the Nuclear and Environmental Technology Division (NETD) of The American Ceramic Society while the Materials Solutions for the Nuclear Renaissance symposium was sponsored by NETD and ASM International.
Download or read book Advances in Materials Science for Environmental and Energy Technologies II written by Josef Matyáš and published by John Wiley & Sons. This book was released on 2013-08-12 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings contains a collection of 24 papers from five 2012Materials Science and Technology (MS&T’12)symposia. Green Technologies for Materials Manufacturing and ProcessingIII Materials Development for Nuclear Applications and ExtremeEnvironments Materials Issues in Nuclear Waste Management in the21st Century Energy Conversion – Photovoltaic, Concentrating SolarPower, and Thermoelectric Energy Storage: Materials, Systems and Applications
Download or read book Crystallization In High Level Waste HLW Glass Melters written by and published by . This book was released on 2014 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Processing strategy for the Hanford Tank Waste Treatment and Immobilization Plant (WTP). 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 higher waste loadings while still meeting process related limits and melter lifetime expectancies. This report provides a review of the scaled melter testing that was completed in support of the Defense Waste Processing Facility (DWPF) melter. Testing with scaled melters provided the data to define the DWPF operating limits to avoid bulk (volume) crystallization in the un-agitated DWPF melter and provided the data to distinguish between spinels generated by K-3 refractory corrosion versus spinels that precipitated from the HLW glass melt pool. This report includes a review of the crystallization observed with the scaled melters and the full scale DWPF melters (DWPF Melter 1 and DWPF Melter 2). Examples of actual DWPF melter attainment with Melter 2 are given. The intent is to provide an overview of lessons learned, including some example data, that can be used to advance the development and implementation of an empirical model and operating limit for crystal accumulation for WTP. Operation of the first and second (current) DWPF melters has demonstrated that the strategy of using a liquidus temperature predictive model combined with a 100 °C offset from the normal melter operating temperature of 1150 °C (i.e., the predicted liquidus temperature (TL) of the glass must be 1050 °C or less) has been successful in preventing any detrimental accumulation of spinel in the DWPF melt pool, and spinel has not been observed in any of the pour stream glass samples. Spinel was observed at the bottom of DWPF Melter 1 as a result of K-3 refractory corrosion. Issues have occurred with accumulation of spinel in the pour spout during periods of operation at higher waste loadings. Given that both DWPF melters were or have been in operation for greater than 8 years, the service life of the melters has far exceeded design expectations. It is possible that the DWPF liquidus temperature approach is conservative, in that it may be possible to successfully operate the melter with a small degree of allowable crystallization in the glass. This could be a viable approach to increasing waste loading in the glass assuming that the crystals are suspended in the melt and swept out through the riser and pour spout. Additional study is needed, and development work for WTP might be leveraged to support a different operating limit for the DWPF. Several recommendations are made regarding considerations that need to be included as part of the WTP crystal tolerant strategy based on the DWPF development work and operational data reviewed here. These include: Identify and consider the impacts of potential heat sinks in the WTP melter and glass pouring system; Consider the contributions of refractory corrosion products, which may serve to nucleate additional crystals leading to further accumulation; Consider volatilization of components from the melt (e.g., boron, alkali, halides, etc.) and determine their impacts on glass crystallization behavior; Evaluate the impacts of glass REDuction/OXidation (REDOX) conditions and the distribution of temperature within the WTP melt pool and melter pour chamber on crystal accumulation rate; Consider the impact of precipitated crystals on glass viscosity; Consider the impact of an accumulated crystalline layer on thermal convection currents and bubbler effectiveness within the melt pool; Evaluate the impact of spinel accumulation on Joule heating of the WTP melt pool; and Inc ...
Download or read book CRYSTALLIZATION IN HIGH LEVEL WASTE GLASSES U S DEPARTMENT OF ENERGY OFFICE OF RIVER PROTECTION WTP ENGINEERING DIVISION written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Various circumstances influence crystallization in glassmaking, for example: (1) crystals nucleate and grow before the glass-forming melt occurs; (2) crystals grow or dissolve in flowing melt and during changing temperature; (3) crystals move under the influence of gravity; (4) crystals agglomerate and interact with gas bubbles; (5) high-level wastes (HLW) are mixtures of a large number of components in unusual proportions; (6) melter processing of HLW and the slow cooling of HLW glass in canisters provides an opportunity for a variety of crystalline forms to precipitate; (7) settling of crystals in a HLW glass melter may produce undesirable sludge at the melter bottom; and (8) crystallization of the glass product may increase, but also ruin chemical durability. The conclusions are: (1) crystal growth and dissolution typically proceed in a convective medium at changing temperature; (2) to represent crystallization or dissolution the kinetics must be expressed in the form of rate equations, such as dC/dt = f(C, T) and the temperature dependence of kinetic coefficients and equilibrium concentrations must be accounted for; and (3) non-equilibrium phenomena commonly occur - metastable crystallization, periodic distribution of crystals; and dendritic crystal growth.
Download or read book Advances in Materials Science for Environmental and Energy Technologies written by Tatsuki Ohji and published by John Wiley & Sons. This book was released on 2012-11-05 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: With contributed papers from the 2011 Materials Science and Technology symposia, this is a useful one-stop resource for understanding the most important issues in advances in materials science for environmental and energy technologies. Logically organized and carefully selected, the articles cover the themes of the symposia: Green Technologies for Materials Manufacturing and Processing; Materials Science Challenges for Nuclear Applications; Materials for Nuclear Waste Disposal and Environmental Cleanup; Energy Conversion/Fuel Cells; and Energy Storage: Materials, Systems and Applications.
Download or read book Characterization of High Level Nuclear Waste Glass Samples Following Extended Melter Idling written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Savannah River Site Defense Waste Processing Facility (DWPF) melter was recently idled with glass remaining in the melt pool and riser for approximately three months. This situation presented a unique opportunity to collect and analyze glass samples since outages of this duration are uncommon. The objective of this study was to obtain insight into the potential for crystal formation in the glass resulting from an extended idling period. The results will be used to support development of a crystal-tolerant approach for operation of the high level waste melter at the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Two glass pour stream samples were collected from DWPF when the melter was restarted after idling for three months. The samples did not contain crystallization that was detectible by X-ray diffraction. Electron microscopy identified occasional spinel and noble metal crystals of no practical significance. Occasional platinum particles were observed by microscopy as an artifact of the sample collection method. Reduction/oxidation measurements showed that the pour stream glasses were fully oxidized, which was expected after the extended idling period. Chemical analysis of the pour stream glasses revealed slight differences in the concentrations of some oxides relative to analyses of the melter feed composition prior to the idling period. While these differences may be within the analytical error of the laboratories, the trends indicate that there may have been some amount of volatility associated with some of the glass components, and that there may have been interaction of the glass with the refractory components of the melter. These changes in composition, although small, can be attributed to the idling of the melter for an extended period. The changes in glass composition resulted in a 70-100 °C increase in the predicted spinel liquidus temperature (TL) for the pour stream glass samples relative to the analysis of the melter feed prior to the outage. This indicates that the potential for spinel crystallization increased as a result of idling for an extended period. However, the predicted TL of the pour stream glasses remained 150-200 °C below the mean melt pool temperature of about 1125 °C during the idling period. Given the change in predicted TL over the three month outage, the results indicate that it is important to have a thorough understanding of spinel crystallization within the melter for WTP to operate with a volume percent crystallization constraint. This knowledge will enable process control routines to be developed that avoid bulk crystallization in the melter and allow for recovery from off-normal events. The current WTP crystal-tolerant glass program will develop an improved understanding of spinel crystallization in the WTP melter to allow for operation at maximum waste loading in glass composition systems limited by predictions of spinel crystallization.
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 Crystallization in High level Waste Glass written by and published by . This book was released on 2015 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a fundamental need to continue research aimed at understanding nepheline and spinel crystal formation in high-level waste (HLW) glass. Specifically, the formation of nepheline solids (K/NaAlSiO4) during slow cooling of HLW glass can reduce the chemical durability of the glass, which can cause a decrease in the overall durability of the glass waste form. The accumulation of spinel solids ((Fe, Ni, Mn, Zn)(Fe, Cr)2O4), while not detrimental to glass durability, can cause an array of processing problems inside HLW glass melters. In this review, the fundamental differences between glass and solid-crystals are explained using kinetic, thermodynamic, and viscosity arguments, and several highlights of glass-crystallization research, as it pertains to high-level waste vitrification, are described. In terms of mitigating spinel in the melter and both spinel and nepheline formation in the canister, the complexity of HLW glass and the intricate interplay between thermal, chemical, and kinetic factors further complicates this understanding. However, new experiments seeking to elucidate the contributing factors of crystal nucleation and growth in waste glass, and the compilation of data from older experiments, may go a long way towards helping to achieve higher waste loadings while developing more efficient processing strategies. Higher waste loadings and more efficient processing strategies will reduce the overall HLW Hanford Tank Waste Treatment and Immobilization Plant (WTP) vitrification facilities mission life.
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 Radioactive Waste Management written by and published by . This book was released on 1981 with total page 630 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
