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Characterization Of High Level Nuclear Waste Glass Samples Following Extended Melter Idling
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Book Synopsis Characterization of High Level Nuclear Waste Glass Samples Following Extended Melter Idling by :
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.
Book Synopsis Advances in Materials Science for Environmental and Energy Technologies IV by : Josef Matyas
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
Book Synopsis Characterization of Radioactive Waste Melter Feed Vitrified By Microwave Energy by : Carol M. Jantzen
Download or read book Characterization of Radioactive Waste Melter Feed Vitrified By Microwave Energy written by Carol M. Jantzen and published by . This book was released on 1992 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. The glass win be processed in the Defense Waste Processing Facility (DWPF) and poured into stainless steel canisters for eventual disposal in a geologic repository. Vitrification of melter feed samples is necessary for DWPF process and product control. Microwave fusion of melter feed at approximately 12OO deg C for 10 minutes has been shown to yield homogeneous glasses comparable to those melted in a conventional furnace for 4 hours. Microwave fusion at lower temperatures for longer times was found to crystallize NiFe2O4 spinel. The use of higher temperatures was determined to cause significant volatilization and recrystallization of the glass. Redox measurements indicated that microwave vitrification of melter slurries may also yield more representative measures of glass Fe2+/Sigma Fe ratio of the glass which is important to melter processing of the glass.
Book Synopsis Glass as a Waste Form and Vitrification Technology by : National Research Council
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:
Book Synopsis Fixation of Radioactive Waste in Glass by :
Download or read book Fixation of Radioactive Waste in Glass written by and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: After a brief review of the source of high level wastes and the specific requirements and desirable characteristics of glass used as a storage vehicle, the development work done on two vitrification systems is outlined. One is an in-can melter system and the second is a ceramic melter. Primary emphasis has been placed on the in-can melter system for use in the near future. Both systems are capable of converting high level waste to a glass which possesses low release potential. (JSR).
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis CHARACTERIZATION OF RADIOACTIVE MACROBATCH 4 GLASS BEING PRODUCED BY THE DWPF AT SAVANNAH RIVER SITE. by :
Download or read book CHARACTERIZATION OF RADIOACTIVE MACROBATCH 4 GLASS BEING PRODUCED BY THE DWPF AT SAVANNAH RIVER SITE. written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: At the Savannah River Site (SRS) the Defense Waste Processing Facility (DWPF) has been immobilizing SRS's radioactive high-level waste (HLW) sludge into a borosilicate glass for approximately nine years. Currently the DWPF is immobilizing HLW sludge in Macrobatch 4 (MB4). Each macrobatch is nominally five hundred thousand gallons of HLW and produces nominally five hundred stainless steel canisters two feet in diameter ten feet tall filled with the borosilicate glass. This paper presents results of the characterization of a sample of MB4 glass taken directly from the pour stream of the DWPF melter during the filling of the canister S02312. This canister was the 275th canister filled during immobilizing MB4. The purpose of the sample was to confirm that the leachability of the glass in a standard ASTM test was less than the leachability criterion set forth in the Waste Acceptance Product Specifications (WAPS) for vitrified waste forms for permanent disposal in a Federal geologic repository. The sample was sent to the Savannah River National Laboratory (SRNL) for characterization.
Book Synopsis High-level Nuclear Waste Borosilicate Glass by :
Download or read book High-level Nuclear Waste Borosilicate Glass written by and published by . This book was released on 1992 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the imminent startup, in the United States, of facilities for vitrification of high-level nuclear waste, a document has been prepared that compiles the scientific basis for understanding the alteration of the waste glass products under the range of service conditions to which they may be exposed during storage, transportation, and eventual geologic disposal. A summary of selected parts of the content of this document is provided. Waste glass alterations in a geologic repository may include corrosion of the glass network due to groundwater and/or water vapor contact. Experimental testing results are described and interpreted in terms of the underlying chemical reactions and physical processes involved. The status of mechanistic modeling, which can be used for long-term predictions, is described and the remaining uncertainties associated with long-term simulations are summarized.
Book Synopsis Annual Report on the Characterization on the High-level Waste Glasses by :
Download or read book Annual Report on the Characterization on the High-level Waste Glasses written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The waste compo itions PW-7c and PW-9 were defined and glass development was completed. Major variations in major oxide concentration would not grossly affect the leach rates of the glass. Impact and strength tests on nonradioactive glass showed that the waste glasses produced slightly less fine particulate than commercial glass. Waste glass had 60% of the strength of the soda-lime glass. A water-quench reduced thermal conductivity about 20%, and a 24-h hold at devitrification temperatures did not produce a significant change. Densities of waste glass at process temperature were 6.6 to 9.3% lower than at room temperature. The effects of glass composition on volatility were measured. Leach tests of highly devitrified samples of 72-68 have shown that leach rates of Cs, Sr and U are increased up to 10X and that Zn leach rates are reduced by nearly 200X. In glass 76-68, where devitrification is much slower, elemental differencesbetween as-formed and thermally-treated samples have not been significant. Average Cs leach rates from the 76-68 glass in an IAEA type long-term test have decreased to 3.3 x 10−8 g/cm2/day. High temperature (250 and 350°C) leach tests showed that glass is comparable to other ceramic materials. In salt brine the glass is rapidly depleted of Cs, Rb and Mo; in water the glass structure is rapidly rearranged to a crystalline structure, and Cs and Rb tend to remain bound in the solid. 76-68 glass (low ZnO) has slow devitrification kinetics compared to 72-68 glass (high ZnO). After equivalent radiation exposures of 300,000 years, the glass buttons still retain their original physical appearance. Stored energy is not a problem for HLW glasses. Density changes are small and do not affect the integrity of the samples. (DLC).
Book Synopsis Annual Report on the Characteristics of High-level Waste Glasses by :
Download or read book Annual Report on the Characteristics of High-level Waste Glasses written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Processes are being developed to immobilize high-level radioactive wastes in glass for increased safety during handling, storage and final disposal. A concurrent program is the characterization of the waste-containing glasses produced by these processes, particularly in relation to their expected long-term behavior as affected by thermal and radiation-induced alteration of the glass. A compilation of characterization data is presented for low-melting (less than 1100°C) borosilicate waste glasses, which may contain 33 wt percent or more waste and which can be melted in situ in their stainless steel storage canisters. The data demonstrate that these low-melting glasses are relatively unaffected by the radiation doses to which they are exposed. The data also show that thermally induced devitrification and phase separation can be minimized by proper selection of glass composition.
Book Synopsis DWPF Vitrification - Characterization of the Radioactive Glass Being Produced During Immobilization of the Second Batch of High Level Waste Sludge by :
Download or read book DWPF Vitrification - Characterization of the Radioactive Glass Being Produced During Immobilization of the Second Batch of High Level Waste Sludge written by and published by . This book was released on 2001 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: This glass sample was then transported to Savannah River Technology Center's (SRTC) Shielded Cells Facility where it was characterized. The characterization includes determining the density of the glass, its nonradioactive and radioactive composition, its durability in a standard ASTM 1285 leach test, and its microstructure. This paper summarizes the results of that characterization. The paper also compares the composition of the glass to that of a glass sample from Macro Batch 1. Lastly the paper also compares the composition of the Macro Batch 2 glass sample to the composition of a sample prepared from the slurry in the MFT when sample was taken from the pour stream. Detailed results of the characterization are presented in three Department of Energy reports that have been released and are available from either author.
Book Synopsis Production of a High-Level Waste Glass from Hanford Waste Samples by :
Download or read book Production of a High-Level Waste Glass from Hanford Waste Samples written by and published by . This book was released on 1998 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes production and characterization of the HLW glass. Production and characterization of the Hanford waste-containing LAW glasses are presented in a related report from this conference.
Book Synopsis High-level Nuclear Waste Borosilicate Glass: a Compendium of Characteristics by :
Download or read book High-level Nuclear Waste Borosilicate Glass: a Compendium of Characteristics written by and published by . This book was released on 1992 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Exploration and Modeling of Structural Changes in Waste Glass Under Corrosion by :
Download or read book Exploration and Modeling of Structural Changes in Waste Glass Under Corrosion written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Vitrification is currently the world-wide treatment of choice for the disposition of high-level nuclear wastes. In glasses, radionuclides are atomistically bonded into the solid, resulting in a highly durable product, with borosilicate glasses exhibiting particularly excellent durability in water. Considering that waste glass is designed to retain the radionuclides within the waste form for long periods, it is important to understand the long-term stability of these materials when they react in the environment, especially in the presence of water. Based on a number of previous studies, there is general consensus regarding the mechanisms controlling the initial rate of nuclear waste glass dissolution. Agreement regarding the cause of the observed decrease in dissolution rate at extended times, however, has been elusive. Two general models have been proposed to explain this behavior, and it has been concluded that both concepts are valid and must be taken into account when considering the decrease in dissolution rate. Furthermore, other processes such as water diffusion, ion exchange, and precipitation of mineral phases onto the glass surface may occur in parallel with dissolution of the glass and can influence long-term performance. Our proposed research will address these issues through a combination of aqueous-phase dissolution/reaction experiments and probing of the resulting surface layers with state-of-the-art analytical methods. These methods include solid-state nuclear magnetic resonance (SSNMR) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The resulting datasets will then be coupled with computational chemistry and reaction-rate modeling to address the most persistent uncertainties in the understanding of glass corrosion, which indeed have limited the performance of the best corrosion models to date. With an improved understanding of corrosion mechanisms, models can be developed and improved that, while still conservative, take advantage of the inherent durability of the waste form to enable secure repositories to be engineered with a much higher density of waste disposition. We propose the synthesis, corrosion, and characterization of two sets of glass samples-- containing approximately 8 single-component oxides each--as models for corrosion studies of more complicated glass systems (which can contain in excess of 25 single-component ingredients). Powdered samples and millimeter- sized coupons of these simpler glasses will be corroded in solutions that begin at circumneutral pH, but are known to increase in alkalinity as corrosion proceeds and saturation in silica species is approached. Through carefully selected isotopic substitutions with nuclides that are readily detected with SSNMR and TOF-SIMS methods, we will be able to follow the diffusion of atoms into and out of the reacted surface layers of these glasses and provide new data for testing with existing reaction models. The models can then be further extended or updated to take our new data into account, allowing the existing long-term glass corrosion models to more accurately reflect the extraordinary durability of these systems. With improved models, a significant opportunity exists to better utilize the storage volume of any geologic repository.
Book Synopsis INTERNATIONAL STUDY OF ALUMINUM IMPACTS ON CRYSTALLIZATION IN U.S. HIGH LEVEL WASTE GLASS. by :
Download or read book INTERNATIONAL STUDY OF ALUMINUM IMPACTS ON CRYSTALLIZATION IN U.S. HIGH LEVEL WASTE GLASS. written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this task was to develop glass formulations for (Department of Energy) DOE waste streams with high aluminum concentrations to avoid nepheline formation while maintaining or meeting waste loading and/or waste throughput expectations as well as satisfying critical process and product performance related constraints. Liquidus temperatures and crystallization behavior were carefully characterized to support model development for higher waste loading glasses. The experimental work, characterization, and data interpretation necessary to meet these objectives were performed among three partnering laboratories: the V.G. Khlopin Radium Institute (KRI), Pacific Northwest National Laboratory (PNNL) and Savannah River National Laboratory (SRNL). Projected glass compositional regions that bound anticipated Defense Waste Processing Facility (DWPF) and Hanford high level waste (HLW) glass regions of interest were developed and used to generate glass compositions of interest for meeting the objectives of this study. A thorough statistical analysis was employed to allow for a wide range of waste glass compositions to be examined while minimizing the number of glasses that had to be fabricated and characterized in the laboratory. The glass compositions were divided into two sets, with 45 in the test matrix investigated by the U.S. laboratories and 30 in the test matrix investigated by KRI. Fabrication and characterization of the US and KRI-series glasses were generally handled separately. This report focuses mainly on the US-series glasses. Glasses were fabricated and characterized by SRNL and PNNL. Crystalline phases were identified by X-ray diffraction (XRD) in the quenched and canister centerline cooled (CCC) glasses and were generally iron oxides and spinels, which are not expected to impact durability of the glass. Nepheline was detected in five of the glasses after the CCC heat treatment. Chemical composition measurements for each of the glasses were conducted following an analytical plan. A review of the individual oxides for each glass revealed that there were no errors in batching significant enough to impact the outcome of the study. A comparison of the measured compositions of the replicates indicated an acceptable degree of repeatability as the percent differences for most of the oxides were less than 5% and percent differences for all of the oxides were less than 10 wt%. Chemical durability was measured using the Product Consistency Test (PCT). All but two of the study glasses had normalized leachate for boron (NL [B]) values that were well below that of the Environmental Assessment (EA) reference glass. The two highest NL [B] values were for the CCC versions of glasses US-18 and US-27 (10.498 g/L and 15.962 g/L, respectively). Nepheline crystallization was identified by qualitative XRD in five of the US-series glasses. Each of these five glasses (US-18, US-26, US-27, US-37 and US-43) showed a significant increase in NL [B] values after the CCC heat treatment. This reduction in durability can be attributed to the formation of nepheline during the slow cooling cycle and the removal of glass formers from the residual glass network. The liquidus temperature (T{sub L}) of each glass in the study was determined by both optical microscopy and XRD methods. The correlation coefficient of the measured XRD TL data versus the measured optical TL data was very good (R2 = 0.9469). Aside from a few outliers, the two datasets aligned very well across the entire temperature range (829 C to 1312 C for optical data and 813 C to 1310 C for XRD crystal fraction data). The data also correlated well with the predictions of a PNNL T{sub L} model. The correlation between the measured and calculated data had a higher degree of merit for the XRD crystal fraction data than for the optical data (higher R2 value of 0.9089 versus 0.8970 for the optical data). The SEM-EDS analysis of select samples revealed the presence of undissolved RuO2 in all glasses due to the low solubility of RuO2 in borosilicate glass. These particles tended to form agglomerates with varying sizes and shapes that were located close to the bottom of crucibles. The results of this study provide further insight into the ability of borosilicate waste glass to incorporate increased (>16 wt %) concentrations of aluminum. The glass composition and properties data will be incorporated into a database of glass composition-property relationships (ComPro) to support further optimization of waste glass compositions at DOE sites.
Download or read book Radioactive Waste Management written by and published by . This book was released on 1981 with total page 726 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Annual report on the characterization of high-level waste glasses by : Pacific Northwest Laboratory
Download or read book Annual report on the characterization of high-level waste glasses written by Pacific Northwest Laboratory and published by . This book was released on 1977 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt:
