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Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel

Description: The U.S. Department of Energy is currently investigating alternative sorbents for the removal and immobilization of radioiodine from the gas streams in a nuclear fuel reprocessing plant. One of these new sorbents, Ag0-functionalized silica aerogels, shows great promise as a potential replacement for Ag-bearing mordenites because of its high selectivity and sorption capacity for iodine. Moreover, a feasible consolidation of iodine-loaded Ag0-functionalized silica aerogels to a durable SiO2-based waste form makes this aerogel an attractive choice for sequestering radioiodine. This report provides a preliminary assessment of the methods that can be used to consolidate iodine-loaded Ag0-functionalized silica aerogels into a final waste form. In particular, it focuses on experimental investigation of densification of as prepared Ag0-functionalized silica aerogels powders, with or without organic moiety and with or without sintering additive (colloidal silica), with three commercially available techniques: 1) hot uniaxial pressing (HUP), 2) hot isostatic pressing (HIP), and 3) spark plasma sintering (SPS). The densified products were evaluated with helium gas pycnometer for apparent density, with the Archimedes method for apparent density and open porosity, and with high-resolution scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) for the extent of densification and distribution of individual elements. The preliminary investigation of HUP, HIP, and SPS showed that these sintering methods can effectively consolidate powders of Ag0-functionalized silica aerogel into products of near-theoretical density. Also, removal of organic moiety and adding 5.6 mass% of colloidal silica to Ag0-functionalized silica aerogel powders before processing provided denser products. Furthermore, the ram travel data for SPS indicated that rapid consolidation of powders can be performed at temperatures below 950°C.
Date: September 1, 2013
Creator: Matyas, Josef & Engler, Robert K.
Partner: UNT Libraries Government Documents Department

Characterization of Dried and Torrefied Arundo Donax Biomass for Inorganic Species Prior to Combustion

Description: Portland General Electric (PGE) potentially plans to replace the coal with torrefied Arundo donax for their Boardman coal-fired power plant by 2020. Since there is only a limited amount of experience with this high yield energy crop, PGE would like to characterize raw and torrefied Arundo before a test burn and therefore avoid possible ash related operational problems such as slagging, deposit formation and corrosion. This report describes the results from characterization of ground and cross-sectioned samples of Arundo with a high-resolution scanning electron microscopy and energy dispersive spectroscopy, and also includes analytical results from a short water-leaching test for concentrations of Ca, Mg, K, Na, S, and Cl in the non-leached and leached Arundo and leachates. SEM-EDS analysis of torrefied Arundo revealed that condensation of volatile components during torrefaction can result in their undesirable re-deposition on the outside surfaces in the form of amorphous or crystallized clusters with a size from a few µm’s to as large as 100 µm. A short exposure of Arundo to water resulted in an efficient removal of volatile species from the raw and torrefied Arundo, e.g., ~ 98 wt% of total K and Cl, and ~75 wt% of total S were removed from raw Arundo, and more than 90 wt% of total K and Cl, and 70 wt% of S from torrefied Arundo, suggesting that water-leaching of Arundo before combustion can be an effective pre-treatment method because high concentrations of Cl increase emissions of HCl, and in combination with K can form large amounts of KCl deposits on boiler surfaces and in combination with H2O or SO3 cause corrosion.
Date: August 1, 2012
Creator: Matyas, Josef; Johnson, Bradley R. & Cabe, James E.
Partner: UNT Libraries Government Documents Department

Characterization of Dry-Air Aged Granules of Silver-Functionalized Silica Aerogel

Description: This is a letter report to complete level 3 milestone "Assess aging characteristics of silica aerogels" for DOE FCRD program. Recently, samples of Ag0-functionalized silica aerogel were aged in flowing dry air for up to 6 months and then loaded with iodine. This dry-air aging simulated the impact of long-term exposure to process gases during process idling. The 6-month aged sample exhibited an iodine sorption capacity of 32 mass%, which was 9 mass % lower than that for an un-aged Ag0-functionalized silica aerogel. In an attempt to understand this decrease in sorption capacity, we characterized physical properties of the aged samples with Brunauer-Emmett-Teller (BET) nitrogen adsorption, X-ray diffraction (XRD), and high resolution scanning electron microscopy (SEM). The results showed no impact of aging on the aerogel microstructure or the silver nanoparticles in the aerogel, including their spatial distribution and morphology.
Date: September 1, 2012
Creator: Matyas, Josef; Fryxell, Glen E. & Robinson, Matthew J.
Partner: UNT Libraries Government Documents Department

Thermal Wadis in Support of Lunar Exploration: Concept Development and Utilization

Description: Thermal wadis, engineered sources of heat, can be used to extend the life of lunar rovers by keeping them warm during the extreme cold of the lunar night. Thermal wadis can be manufactured by sintering or melting lunar regolith into a solid mass with more than two orders of magnitude higher thermal diffusivities compared to native regolith dust. Small simulant samples were sintered and melted in the electrical furnaces at different temperatures, different heating and cooling rates, various soaking times, under air, or in an argon atmosphere. The samples were analyzed with scanning electron microscopy and energy dispersive spectroscopy, X-ray diffraction, a laser-flash thermal diffusivity system, and the millimeter-wave system. The melting temperature of JSC-1AF simulant was ~50°C lower in an Ar atmosphere compared to an air atmosphere. The flow of Ar during sintering and melting resulted in a small mass loss of 0.04 to 0.1 wt% because of the volatization of alkali compounds. In contrast, the samples that were heat-treated under an air atmosphere gained from 0.012 to 0.31 wt% of the total weight. A significantly higher number of cavities were formed inside the samples melted under an argon atmosphere, possibly because of the evolution of oxygen bubbles from iron redox reactions. The calculated emissivity of JSCf-1AF simulant did not change much with temperature, varying between 0.8 and 0.95 at temperatures from 100 to 1200°C. The thermal diffusivities of raw regolith that was compressed under a pressure of 9 metric tons ranged from 0.0013 to 00011 in the 27 to 390°C temperature range. The thermal diffusivities of sintered and melted JSC-1AF simulant varied from 0.0028 to 0.0072 cm2/s with the maximum thermal diffusivities observed in the samples that were heated up 5°C/min from RT to 1150°C under Ar or air. These thermal diffusivities are high enough for the rovers ...
Date: October 12, 2009
Creator: Matyas, Josef; Wegeng, Robert S. & Burgess, Jeremy M.
Partner: UNT Libraries Government Documents Department

Laboratory-Scale Melter for Determination of Melting Rate of Waste Glass Feeds

Description: The purpose of this study was to develop the laboratory-scale melter (LSM) as a quick and inexpensive method to determine the processing rate of various waste glass slurry feeds. The LSM uses a 3 or 4 in. diameter-fused quartz crucible with feed and off-gas ports on top. This LSM setup allows cold-cap formation above the molten glass to be directly monitored to obtain a steady-state melting rate of the waste glass feeds. The melting rate data from extensive scaled-melter tests with Hanford Site high-level wastes performed for the Hanford Tank Waste Treatment and Immobilization Plant have been compiled. Preliminary empirical model that expresses the melting rate as a function of bubbling rate and glass yield were developed from the compiled database. The two waste glass feeds with most melter run data were selected for detailed evaluation and model development and for the LSM tests so the melting rates obtained from LSM tests can be compared with those from scaled-melter tests. The present LSM results suggest the LSM setup can be used to determine the glass production rates for the development of new glass compositions or feed makeups that are designed to increase the processing rate of the slurry feeds.
Date: January 9, 2012
Creator: Kim, Dong-Sang; Schweiger, Michael J.; Buchmiller, William C. & Matyas, Josef
Partner: UNT Libraries Government Documents Department

Melt Rate Improvement for High-Level Waste Glass

Description: This report summarizes results of research accomplished during the first year of the 3-year project. The data presented in this report have been gathered to support work on the mathematical modeling of waste-glass melters. At this stage, only a qualitative description and interpretation of the observed phenomena has been attempted. Two Savannah Rive feeds were used for the study. These feeds were subjected to thermal gravimetric analysis, differential thermal analysis, differential scanning calorimetry, evolved gas analysis with volume-expansion monitoring, modified reboil test, quantitative X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, wet chemical analysis, and M?ssbauer spectroscopy. Glass viscosity was also measured. Finally, it was recommended to use melt-rate furnace test data to measure thermal diffusivity of the feed. Though both feed were reduced to prevent oxygen evolution from the melt, oxygen evolved form one of the melts and COx evolved from both. Hence, foam is likely to form under the cold cap even when the feed is reduced. An important difference between the feeds was in the melt viscosity at the temperature at which the melt interfaces the cold cap. It was suggested that low viscosity destabilizes foam under the cold cap, thus enhancing the rate of melting.
Date: September 9, 2002
Creator: Matyas, Josef; Hrma, Pavel R. & Kim, Dong-Sang
Partner: UNT Libraries Government Documents Department

The effect of high-level waste glass composition on spinel liquidus temperature

Description: Spinel crystals precipitate in high-level waste glasses containing Fe, Cr, Ni, Mn, Zn, and Ru. The liquidus temperature (T{sub L}d) of spinel as the primary crystallization phase is a function of glass composition, and the spinel solubility (c{sub o}) is a function of both glass composition and temperature (T). Previously reported models of T{sub L} as a function of composition are based on T{sub L} measured directly, which requires laborious experimental procedures. Viewing the curve of c{sub o} versus T as the liquidus line allows a significant broadening of the composition region for model fitting. This paper estimates T{sub L} as a function of composition based on c{sub o} data obtained with the X-ray diffraction technique.
Date: November 15, 2012
Creator: Kruger, A. A.; Riley, Brian J.; Crum, Jarrod V.; Hrma, Pavel & Matyas, Josef
Partner: UNT Libraries Government Documents Department

Foaming of E-Glass II (Report for G Plus Project for PPG)

Description: In a previous study, the effect of the furnace atmosphere on E glass foaming was investigated with the specific goal to understand the impact of increased water content on foaming in oxy-fired furnaces. The present study extended the previous study and focused on the effect of glass batch chemical composition on E-glass foaming. The present study also included reruns of foam tests performed in a previous study, which resulted in the same trend: the foaming extent increased nearly linearly with the heating rate and no foam was produced when CO2 + 55% H2O atmosphere was introduced at 300°C. It was shown that the lack of foaming in the test with CO2 + 55% H2O atmosphere introduced at 300°C was caused by a loss of sulfate at T <1250°C because of higher water content at the early stages of melting. The tests with new batches in the present study showed that replacing quicklime with limestone tend to decrease foaming, possibly caused by increased sulfate loss during early stages of melting in the batch with limestone. The batches where Na2SO4 was replaced with NaNO3, NaNO3 + CeO2, or CeO2, produced only very limited foaming regardless of the replacing components. As expected, the foaming extent increased as the sulfate content in the batch increased. The results of the present study suggest that foaming can be reduced by using limestone over quicklime and by decreasing the sulfate addition to a minimum required for refining.
Date: September 23, 2005
Creator: Kim, Dong-Sang; Portch, Matthew P.; Matyas, Josef; Hrma, Pavel R. & Pilon, Laurent
Partner: UNT Libraries Government Documents Department

Crystal-Tolerant Glass Approach For Mitigation Of Crystal Accumulation In Continuous Melters Processing Radioactive Waste

Description: High-level radioactive waste melters are projected to operate in an inefficient manner as they are subjected to artificial constraints, such as minimum liquidus temperature (T{sub L}) or maximum equilibrium fraction of crystallinity at a given temperature. These constraints substantially limit waste loading, but were imposed to prevent clogging of the melter with spinel crystals [(Fe, Ni, Mn, Zn)(Fe, Cr){sub 2}O{sub 4}]. In the melter, the glass discharge riser is the most likely location for crystal accumulation during idling because of low glass temperatures, stagnant melts, and small diameter. To address this problem, a series of lab-scale crucible tests were performed with specially formulated glasses to simulate accumulation of spinel in the riser. Thicknesses of accumulated layers were incorporated into empirical model of spinel settling. In addition, T{sub L} of glasses was measured and impact of particle agglomeration on accumulation rate was evaluated. Empirical model predicted well the accumulation of single crystals and/or smallscale agglomerates, but, excessive agglomeration observed in high-Ni-Fe glass resulted in an under-prediction of accumulated layers, which gradually worsen over time as an increased number of agglomerates formed. Accumulation rate of ~14.9 +- 1 nm/s determined for this glass will result in ~26 mm thick layer in 20 days of melter idling.
Date: August 28, 2012
Creator: Kruger, Albert A.; Rodriguez, Carmen P.; Lang, Jesse B.; Huckleberry, Adam R.; Matyas, Josef & Owen, Antoinette T.
Partner: UNT Libraries Government Documents Department

Alternative Waste Forms for Electro-Chemical Salt Waste

Description: This study was undertaken to examine alternate crystalline (ceramic/mineral) and glass waste forms for immobilizing spent salt from the Advanced Fuel Cycle Initiative (AFCI) electrochemical separations process. The AFCI is a program sponsored by U.S. Department of Energy (DOE) to develop and demonstrate a process for recycling spent nuclear fuel (SNF). The electrochemical process is a molten salt process for the reprocessing of spent nuclear fuel in an electrorefiner and generates spent salt that is contaminated with alkali, alkaline earths, and lanthanide fission products (FP) that must either be cleaned of fission products or eventually replaced with new salt to maintain separations efficiency. Currently, these spent salts are mixed with zeolite to form sodalite in a glass-bonded waste form. The focus of this study was to investigate alternate waste forms to immobilize spent salt. On a mole basis, the spent salt is dominated by alkali and Cl with minor amounts of alkaline earth and lanthanides. In the study reported here, we made an effort to explore glass systems that are more compatible with Cl and have not been previously considered for use as waste forms. In addition, alternate methods were explored with the hope of finding a way to produce a sodalite that is more accepting of as many FP present in the spent salt as possible. This study was done to investigate two different options: (1) alternate glass families that incorporate increased concentrations of Cl; and (2) alternate methods to produce a mineral waste form.
Date: October 28, 2009
Creator: Crum, Jarrod V.; Sundaram, S. K.; Riley, Brian J.; Matyas, Josef; Arreguin, Shelly A. & Vienna, John D.
Partner: UNT Libraries Government Documents Department

HLW Glass Studies: Development of Crystal-Tolerant HLW Glasses

Description: In our study, a series of lab-scale crucible tests were performed on designed glasses of different compositions to further investigate and simulate the effect of Cr, Ni, Fe, Al, Li, and RuO2 on the accumulation rate of spinel crystals in the glass discharge riser of the HLW melter. The experimental data were used to expand the compositional region covered by an empirical model developed previously (Matyáš et al. 2010b), improving its predictive performance. We also investigated the mechanism for agglomeration of particles and impact of agglomerates on accumulation rate. In addition, the TL was measured as a function of temperature and composition.
Date: April 2, 2012
Creator: Matyas, Josef; Huckleberry, Adam R.; Rodriguez, Carmen P.; Lang, Jesse B.; Owen, Antionette T. & Kruger, Albert A.
Partner: UNT Libraries Government Documents Department

Development of Crystal-Tolerant High-Level Waste Glasses

Description: 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-μm 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 ...
Date: December 17, 2010
Creator: Matyas, Josef; Vienna, John D.; Schaible, Micah J.; Rodriguez, Carmen P.; Crum, Jarrod V.; Arrigoni, Alyssa L. et al.
Partner: UNT Libraries Government Documents Department

Summary Report for the Development of Materials for Volatile Radionuclides

Description: The materials development summarized here is in support of the Waste Forms campaign, Volatile Radionuclide task. Specifically, materials are being developed for the removal and immobilization of iodine and krypton, specifically 129I and 85Kr. During FY 2010, aerogel materials were investigated for removal and immobilization of 129I. Two aerogel formulations were investigated, one based on silica aerogels and the second on chalcogenides. For 85Kr, metal organic framework (MOF) structures were investigated.
Date: November 22, 2010
Creator: Strachan, Denis M.; Chun, Jaehun; Henager, Charles H.; Matyas, Josef; Riley, Brian J.; Ryan, Joseph V. et al.
Partner: UNT Libraries Government Documents Department

Summary Report on the Volatile Radionuclide and Immobilization Research for FY2011 at PNNL

Description: The materials development summarized here is in support of the Waste Forms campaign, Volatile Radionuclide task. Specifically, materials are being developed for the removal and immobilization of iodine and krypton, specifically 129I and 85Kr. During FY 2011, aerogel materials were investigated for removal and immobilization of 129I. Two aerogel formulations were investigated, one based on silica aerogels and the second on chalcogen-based aerogels (i.e., chalcogels). A silica aerogel was tested at ORNL for total I2 sorption capacity. It was determined to have 48 mass% capacity while having little physisorbed I2 (I2 not taken up in the aerogel pores). For 85Kr, metal organic framework (MOF) structures were investigated and a new MOF with about 8 mass% capacity for Xe and Kr. The selectivity can be changed from Xe &gt; Kr to Xe &lt; Kr simply by lowering the temperature below 0 C. A patent disclosure has been filed. Lastly, silicon carbide (SiC) was loaded with Kr. The diffusion of Kr in SiC was found to be less than detectable at 500 C.
Date: September 1, 2011
Creator: Strachan, Denis M.; Chun, Jaehun; Matyas, Josef; Lepry, William C.; Riley, Brian J.; Ryan, Joseph V. et al.
Partner: UNT Libraries Government Documents Department

Alternative Electrochemical Salt Waste Forms, Summary of FY2010 Results

Description: In FY2009, PNNL performed scoping studies to qualify two waste form candidates, tellurite (TeO2-based) glasses and halide minerals, for the electrochemical waste stream for further investigation. Both candidates showed promise with acceptable PCT release rates and effective incorporation of the 10% fission product waste stream. Both candidates received reprisal for FY2010 and were further investigated. At the beginning of FY2010, an in-depth literature review kicked off the tellurite glasses study. The review was aimed at ascertaining the state-of-the-art for chemical durability testing and mixed chloride incorporation for tellurite glasses. The literature review led the authors to 4 unique binary and 1 unique ternary systems for further investigation which include TeO2 plus the following: PbO, Al2O3-B2O3, WO3, P2O5, and ZnO. Each system was studied with and without a mixed chloride simulated electrochemical waste stream and the literature review provided the starting points for the baseline compositions as well as starting points for melting temperature, compatible crucible types, etc. The most promising glasses in each system were scaled up in production and were analyzed with the Product Consistency Test, a chemical durability test. Baseline and PCT glasses were analyzed to determine their state, i.e., amorphous, crystalline, phase separated, had undissolved material within the bulk, etc. Conclusions were made as well as the proposed direction for FY2011 plans. Sodalite was successfully synthesized by the sol-gel method. The vast majority of the dried sol-gel consisted of sodalite with small amounts of alumino-silicates and unreacted salt. Upon firing the powders made by sol-gel, the primary phase observed was sodalite with the addition of varying amounts of nepheline, carnegieite, lithium silicate, and lanthanide oxide. The amount of sodalite, nepheline, and carnegieite as well as the bulk density of the fired pellets varied with firing temperature, sol-gel process chemistry, and the amount of glass sintering aid added ...
Date: August 1, 2010
Creator: Riley, Brian J.; Rieck, Bennett T.; Crum, Jarrod V.; Matyas, Josef; McCloy, John S.; Sundaram, S. K. et al.
Partner: UNT Libraries Government Documents Department

Testing of Large-Scale ICV Glasses with Hanford LAW Simulant

Description: Preliminary glass compositions for immobilizing Hanford low-activity waste (LAW) by the in-container vitrification (ICV) process were initially fabricated at crucible- and engineering-scale, including simulants and actual (radioactive) LAW. Glasses were characterized for vapor hydration test (VHT) and product consistency test (PCT) responses and crystallinity (both quenched and slow-cooled samples). Selected glasses were tested for toxicity characteristic leach procedure (TCLP) responses, viscosity, and electrical conductivity. This testing showed that glasses with LAW loading of 20 mass% can be made readily and meet all product constraints by a far margin. Glasses with over 22 mass% Na2O can be made to meet all other product quality and process constraints. Large-scale testing was performed at the AMEC, Geomelt Division facility in Richland. Three tests were conducted using simulated LAW with increasing loadings of 12, 17, and 20 mass% Na2O. Glass samples were taken from the test products in a manner to represent the full expected range of product performance. These samples were characterized for composition, density, crystalline and non-crystalline phase assemblage, and durability using the VHT, PCT, and TCLP tests. The results, presented in this report, show that the AMEC ICV product with meets all waste form requirements with a large margin. These results provide strong evidence that the Hanford LAW can be successfully vitrified by the ICV technology and can meet all the constraints related to product quality. The economic feasibility of the ICV technology can be further enhanced by subsequent optimization.
Date: March 1, 2005
Creator: Hrma, Pavel R.; Kim, Dong-Sang; Vienna, John D.; Matyas, Josef; Smith, Donald E.; Schweiger, Michael J. et al.
Partner: UNT Libraries Government Documents Department

Bulk Vitrification Castable Refractory Block Protection Study

Description: Bulk vitrification (BV) was selected for a pilot-scale test and demonstration facility for supplemental treatment to accelerate the cleanup of low-activity waste (LAW) at the Hanford U.S. DOE Site. During engineering-scale (ES) tests, a small fraction of radioactive Tc (and Re, its nonradioactive surrogate) were transferred out of the LAW glass feed and molten LAW glass, and deposited on the surface and within the pores of the castable refractory block (CRB). Laboratory experiments were undertaken to understand the mechanisms of the transport Tc/Re into the CRB during vitrification and to evaluate various means of CRB protection against the deposition of leachable Tc/Re. The tests used Re as a chemical surrogate for Tc. The tests with the baseline CRB showed that the molten LAW penetrates into CRB pores before it converts to glass, leaving deposits of sulfates and chlorides when the nitrate components decompose. Na2O from the LAW reacts with the CRB to create a durable glass phase that may contain Tc/Re. Limited data from a single CRB sample taken from an ES experiment indicate that, while a fraction of Tc/Re is present in the CRB in a readily leachable form, most of the Tc/Re deposited in the refractory is retained in the form of a durable glass phase. In addition, the molten salts from the LAW, mainly sulfates, chlorides, and nitrates, begin to evaporate from BV feeds at temperatures below 800 C and condense on solid surfaces at temperatures below 530 C. Three approaches aimed at reducing or preventing the deposition of soluble Tc/Re within the CRB were proposed: metal lining, sealing the CRB surface with a glaze, and lining the CRB with ceramic tiles. Metal liners were deemed unsuitable because evaluations showed that they can cause unacceptable distortions of the electric field in the BV system. Sodium silicate and ...
Date: May 1, 2005
Creator: Hrma, Pavel R.; Bagaasen, Larry M.; Beck, Andrew E.; Brouns, Thomas M.; Caldwell, Dustin D.; Elliott, Michael L. et al.
Partner: UNT Libraries Government Documents Department

Processes for Removal and Immobilization of 14C, 129I, and 85Kr

Description: This is a white paper covering the results of a literature search and preliminary experiments on materials and methods to remove and immobilize gaseous radionuclided that come from the reprocessing of spent nuclear fuel.
Date: October 5, 2009
Creator: Strachan, Denis M.; Bryan, Samuel A.; Henager, Charles H.; Levitskaia, Tatiana G.; Matyas, Josef; Thallapally, Praveen K. et al.
Partner: UNT Libraries Government Documents Department

Alternative Electrochemical Salt Waste Forms, Summary of FY/CY2011 Results

Description: This report summarizes the 2011 fiscal+calendar year efforts for developing waste forms for a spent salt generated in reprocessing nuclear fuel with an electrochemical separations process. The two waste forms are tellurite (TeO2-based) glasses and sol-gel-derived high-halide mineral analogs to stable minerals found in nature.
Date: December 1, 2011
Creator: Riley, Brian J.; McCloy, John S.; Crum, Jarrod V.; Rodriguez, Carmen P.; Windisch, Charles F.; Lepry, William C. et al.
Partner: UNT Libraries Government Documents Department

Investigation of Tc Migration Mechanism During Bulk Vitrification Process Using Re Surrogate

Description: As a part of Bulk vitrification (BV) performance enhancement tasks, Laboratory scoping tests were performed in FY 2004-2005 to explore possible ways to reduce the amount of soluble Tc in the BV waste package. Theses scoping tests helped identify which mechanisms play an important role in the migration of Tc in the BV process (Hrma et al. 2005 and Kim et al. 2005). Based on the results from these scoping tests, additional tests were identified that will improve the understanding of Tc migration and to clearly identify the dominant mechanisms. The additional activities identified from previous studies were evaluated and prioritized for planning for Tasks 29 and 30 conducted in FY2006. Task 29 focused on the improved understanding of Tc migration mechanisms, and Task 30 focused on identifying the potential process changes that might reduce Tc/Re migration into the castable refractory block (CRB). This report summarizes the results from the laboratory- and crucible-scale tests in the lab for improved Tc migration mechanism understanding utilizing Re as a surrogate performed in Task 29.
Date: December 4, 2006
Creator: Kim, Dong-Sang; Bagaasen, Larry M.; Crum, Jarrod V.; Fluegel, Alex; Gallegos, Autumn B.; Martinez, Baudelio et al.
Partner: UNT Libraries Government Documents Department

Bulk Vitrification Performance Enhancement: Refractory Lining Protection Against Molten Salt Penetration

Description: Bulk vitrification (BV) is a process that heats a feed material that consists of glass-forming solids and dried low-activity waste (LAW) in a disposable refractory-lined metal box using electrical power supplied through carbon electrodes. The feed is heated to the point that the LAW decomposes and combines with the solids to generate a vitreous waste form. This study supports the BV design and operations by exploring various methods aimed at reducing the quantities of soluble Tc in the castable refractory block portion of the refractory lining, which limits the effectiveness of the final waste form.
Date: August 6, 2007
Creator: Hrma, Pavel R.; Bagaasen, Larry M.; Schweiger, Michael J.; Evans, Michael B.; Smith, Benjamin T.; Arrigoni, Benjamin M. et al.
Partner: UNT Libraries Government Documents Department