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Characterization of a Pu-bearing zirconolite-rich synroc

Description: A titanate-based ceramic waste form, rich in phases structurally related to zirconolite (CaZrTi{sub 2}O{sub 7}), is being developed as a possible method for immobilizing excess plutonium from dismantled nuclear weapons. As part of this program, Lawrence Livermore National Laboratory (LLNL) produced several ceramics that were then characterized at Argonne National Laboratory (ANL). The plutonium- loaded ceramic was found to contain a Pu-Gd zirconolite phase but also contained plutonium titanates, Gd-polymignyte, and a series of other phases. In addition, much of the Pu was remained as PuO{sub 2- x}. The Pu oxidation state in the zirconolite was determined to be mainly Pu{sup 4+}, although some Pu{sub 3+} was believed to be present.
Date: December 31, 1996
Creator: Buck, E.C.; Ebbinghaus, B.; Bakel, A.J. & Bates, J.K.
Partner: UNT Libraries Government Documents Department

Leach testing of waste forms: interrelationship of ISO- and MCC-type tests

Description: Leach testing experiments were conducted on SYNROC-D material to examine the parameters which affect leaching results and to measure the activation energy for leaching of elements from SYNROC-D. Measured leach rates were found to be controlled by precipitation of insoluble phases for those tests where the sample surface area to volume of leachant (SA/V) multiplied by leaching time (t) exceeded 0.3 cm{sup -1}d for leach tests at 90{sup 0}C. In these cases the apparent activation energy for leaching was approximately 10 kcal/mole based on Na and Si data. For leach tests at 90{sup 0}C with (SA/V)(t) less than 0.2 cm{sup -1}d, the activation energy for Na and Si dissolution was 18.5 kcal/mole for sample S29 and 14.5 kcal/mole for sample LS04. These activation energies are in agreement with values reported by Tole and Lasaga (1981) for nepheline dissolution. The effect of sample geometry was investigated by leaching a series of crushed samples of different grain size. The results support the view that geometric surface area should be used in leach rate calculations rather than gas adsorption BET surface area. Comparison of results on S29 leaching of crushed samples and monoliths show that data from MCC-1 and ISO type leach tests may be directly compared when the data are examined at constant (SA/V)(t).
Date: May 14, 1982
Creator: Oversby, V.M.
Partner: UNT Libraries Government Documents Department

Electrical resistivity measurements of brine saturated porous media near reservoir conditions: Awibengkok preliminary results

Description: Laboratory measurements of the electrical resistivity of rocks and synthetic rocks with confining pressures up to 100 bars and temperatures between 20 and 211 C were performed to further investigate how the pore-size distribution and capillarity affects boiling in porous media. Similar to previous measurements on samples from The Geysers, CA, we observed a gradual increase in resistivity when pore pressure was decreased below the phase-boundary pressure of free water, an indication that boiling is controlled not only by temperature and pressure, but also by pore size distribution. Other important phenomena observed were strong resistance fluctuations during boiling that may be chaotic, and salt deposition that caused sample cracking. If confirmed in further experiments, these results may lead to a new geophysical diagnostic for locating boiling in high permeability areas of geothermal reservoirs and for methods of permeability alteration.
Date: June 28, 1999
Creator: Bonner, B; Duba, A & Roberts, J
Partner: UNT Libraries Government Documents Department

Engineering Study of the Hanford Low Activity Waste (LAW) Steam Reforming Process

Description: The fluidized bed steam reforming (FBSR) technology should be further evaluated as a final waste form for Hanford LAW wastes. This technology produces stable mineralized phases which are more durable than a high sodium vitrified waste form. The mineral phases are the same as many of the phases produced in higher temperature waste forms such as supercalcine, glass-bonded ceramics, and SYNthetic ROCk (SYNROC) yet the phases are produced at moderate steam reformer operating temperatures. The mineral phases bind the radionuclide and hazardous species in cage structured mineral phases. The radionuclides and hazardous species are ionically bonded to silica and alumina tetrahedra in the structure as well as to Na ions.
Date: September 23, 2002
Creator: Jantzen, C.M.
Partner: UNT Libraries Government Documents Department

Evaluation of the Use of Synroc to Solidify the Cesium and Strontium Separations Product from Advanced Aqueous Reprocessing of Spent Nuclear Fuel

Description: This report is a literature evaluation on the Synroc process for determining the potential for application to solidification of the Cs/Sr strip product from advanced aqueous fuel separations activities.
Date: March 1, 2006
Creator: Tripp, Julia & Maio, Vince
Partner: UNT Libraries Government Documents Department

Demonstration of pu immobilization in synroc at the 50g of PuO{sub 2} scale

Description: The immobilization of 13.5 wt% PuO{sub 2} in a zirconolite-rich Synroc has been demonstrated at the 50 g PuO{sub 2} scale in cans produced by hot isostatic pressing (HIPing) at 1280 C. The wasteform also contains more than an equimolar amount of neutron poisons such as Gd, Sm and Hf. The scale-up technology for production of Pu-containing cans of Synroc by HIPing has been demonstrated at the 10 kg scale using CeO{sub 2} as an analog for PuO{sub 2}. The characterization of the products has shown that Ce is a good analog for Pu in zirconolite-rich Synroc produced by HIPing. Post-production thermal tests simulating the effects of a HLW glass pour in a surrounding canister have shown that the Synroc is stable and there is no exsolution of PuO{sub 2} or CeO{sub 2}.
Date: June 1, 1997
Creator: Moricca, S; Brownscombe, A J; Webb, N; Stewart,M W A; Day, R A; Hambley, M et al.
Partner: UNT Libraries Government Documents Department

Final Report on Initial Samples Supplied by LLNL for Task 3.3 Binder Burnout and Sintering Schedule Optimisation

Description: Sixteen of the twenty-one samples have been investigated using the scanning laser dilatometer. This includes all three types of samples with different preparation routes and organic content. Cracks were observed in all samples, even those only heated to 300 C. It was concluded that the cracking was occurring in the early part of the heat treatment before the samples reached 300 C. Increase in the rate of dilation of the samples occurred above 170 C which coincided with the decomposition of the binder/wax additives as determined by differential thermal analysis. A comparison was made with SYNROC C material (Powder Run 143), samples of which had been CIPed and green machined to a similar diameter and thickness as the 089mm SRTC pucks. These samples contained neither binder nor other organic processing aids and had been kept in the same desiccator as the SRTC samples. The CIPed Synroc C samples sintered to high density with zero cracks. As the cracks made up only a small contribution to the change in diameter of the sample compared to the sintering shrinkage, useful information could still be gained from the runs. The sintering curves showed that there was much greater shrinkage of the Type III samples containing only the 5% PEG binder compared to the Type I which contained polyolefin wax as processing aid. Slight changes in gradient of the sintering curve were observed, however, due to the masking effect of the cracking, full analysis of the sintering kinetics cannot be conducted. Even heating the samples to 300 C at 1.0 or 0.5 C/min could not prevent crack formation. This indicated that heating rate was not the critical parameter causing cracking of the samples. Sectioning of green bodies revealed the inhomogeneous nature of the binder/lubricant distribution in the samples. Increased homogeneity would reduce the amount ...
Date: January 4, 1999
Creator: Walls, P
Partner: UNT Libraries Government Documents Department

The CaO-TiO{sub 2}-ZrO{sub 2} system at 1,200{degree}C and the solubilities of Hf and Gd in zirconolite

Description: In recent years, significant technological advancements have been made in the Synroc scheme for the immobilization high-level nuclear waste. However, many basic scientific issues related to Synroc fabrication have yet to be addressed. The CaO-TiO{sub 2}-ZrO{sub 2} system is an integral part of the Synroc formulation. Phase equilibria are established in the CaO-TiO{sub 2}-ZrO{sub 2} system at 1,200 C, using X-ray diffraction and electron probe microanalysis. The existence of two previously reported ternary phases, zirconolite (CaZrTi{sub 2}O{sub 7}) and calzirtite (Ca{sub 2}Zr{sub 5}Ti{sub 2}O{sub 16}), is confirmed. Each of these phases exhibits a significant range of homogeneity between TiO{sub 2} and ZrO{sub 2} while maintaining a nearly constant concentration of CaO. The ternary solubilities of the constituent binary phases are found to be negligible, with the exceptions of the perovskites, which display mutual solubility of at least 22 mol.% and may in fact form a series of continuous solid solutions. The solubilities of Hf and Gd in zirconolite are also investigated. While Hf-bearing samples did not reach thermodynamic equilibrium under the experimental conditions employed, the existence of a Hf analog to zirconolite, CaHfTi{sub 2}O{sub 7}, is conclusively demonstrated. The phase is stable at the stoichiometric composition, and its lattice parameters are very close to those reported in the literature for stoichiometric zirconolite. A Gd-bearing sample of the composition Ca{sub 0.88}Zr{sub 0.88}Gd{sub 9.24}Ti{sub 2}O{sub 7} is found to be essentially single phase zirconolite, in agreement with previous investigations at higher temperatures.
Date: December 1, 1995
Creator: Swenson, D.; Nieh, T.G. & Fournelle, J.H.
Partner: UNT Libraries Government Documents Department

Final report on initial samples supplied by LLNL for task 3.3 binder burnout and sintering schedule optimisation

Description: Sixteen of the twenty-one samples have been investigated using the scanning laser dilatometer. This includes all three types of samples with different preparation routes and organic content. Cracks were observed in all samples, even those only heated to 300 C. It was concluded that the cracking was occurring in the early part of the heat treatment before the samples reached 300 C. Increase in the rate of dilation of the samples occurred above 170 C which coincided with the decomposition of the binder/wax additives as determined by differential thermal analysis. A comparison was made with SYNROC C material (Powder Run 143), samples of which had been CIPed and green machined to a similar diameter and thickness as the 089 mm SRTC pucks. These samples contained neither binder nor other organic processing aids and had been kept in the same desiccator as the SRTC samples. The CIPed Synroc C samples sintered to high density with zero cracks. As the cracks made up only a small contribution to the change in diameter of the sample compared to the sintering shrinkage, useful information could still be gained from the runs. The sintering curves showed that there was much greater shrinkage of the Type III samples containing only the 5% PEG binder compared to the Type I which contained polyolefin wax as processing aid. Slight changes in gradient of the sintering curve were observed, however, due to the masking effect of the cracking, full analysis of the sintering kinetics cannot be conducted. Even heating the samples to 300 C at 1.0 or 0.5 C/min could not prevent crack formation. This indicated that heating rate was not the critical parameter causing cracking of the samples. Sectioning of green bodies revealed the inhomogeneous nature of the binder/lubricant distribution in the samples. Increased homogeneity would reduce the ...
Date: January 4, 1999
Creator: Walls, P
Partner: UNT Libraries Government Documents Department

FUNDAMENTAL THERMODYNAMICS OF ACTINIDE-BEARING MINERAL WASTE FORMS

Description: In September 2000, the US and Russia reached an agreement to jointly disposition roughly 68 metric tons of weapons usable plutonium. (Agreement 2000) In Russia, 34 metric tonnes of weapons-grade plutonium will be dispositioned by burning the plutonium as mixed oxide (MOX) fuel. In the US, 25 metric tons of plutonium recovered from pits and clean metal will likewise be dispositioned by burning as mixed oxide (MOX) fuel and about 9 metric tonnes of plutonium stored throughout the DOE complex will be dispositioned by immobilization in a ceramic which will then be encapsulated in high-level waste (HLW) glass. In all cases, the plutonium will be made equal to or less attractive for reuse in nuclear weapons than the much larger and growing inventory of plutonium in spent nuclear fuel. This threshold of unattractiveness is commonly referred to as the ''spent fuel standard.'' In the US, the final products from plutonium disposition, irradiated fuel and ceramic encapsulated HLW, will be emplaced in the Federal Waste Repository, which is assumed to be Yucca Mountain. The ceramic form selected for the disposition of plutonium is composed of a series of titanate-based phases which are generally referred to as SYNROC (short for Synthetic Rock). The particular formulation that was selected is composed of about 80 vol % pyrochlore, about 15 vol % brannerite, and about 5 vol % rutile. If impurities are present in the PuO{sub 2} feed material, about a half a dozen other phases can also form. The most common of these are zirconolite and a silicate glass. A screening process conducted in 1995, resulted in the selection of borosilicate glasses and titanate-based ceramics (e.g. SYNROCs) as the best available options for immobilization of plutonium. In 1998, a pyrochlore-rich ceramic form was selected in preference to a boro-silicate glass form. More information ...
Date: January 1, 2001
Creator: WILLIAMSON, M.; HUANG, J. & PUTNAM, R.
Partner: UNT Libraries Government Documents Department

Nineteenth annual actinide separations conference: Conference program and abstracts

Description: This report contains the abstracts from the conference presentations. Sessions were divided into the following topics: Waste treatment; Spent fuel treatment; Issues and responses to Defense Nuclear Facility Safety Board 94-1; Pyrochemical technologies; Disposition technologies; and Aqueous separation technologies.
Date: December 31, 1995
Creator: Bronson, M.
Partner: UNT Libraries Government Documents Department

New Metal Niobate and Silicotitanate Ion Exchangers: Development and Characterization

Description: This project is a continuing EMSP project entitled ''New Silicotitanate Waste Forms: Development and Characterization.'' In our original study, the phase selection and chemical durability of silicotitanates (including commercially available IE-911) as a function of temperature (500 to 1000 C) was fully characterized by a combination of techniques including XRD, TEM, SEM, NMR, Raman spectroscopy, XAFS, XANES, and by thermodynamic studies. In addition, work on this program led to new discoveries not anticipated in the originally proposed research. Of particular importance was the discovery of a new ion exchange material that is selective for divalent cations under extreme conditions (e.g., acid solutions, competing cations), thus providing an alternative for removing Sr from mixed wastes. This material is converted easily by high-temperature, in situ heat treatment into a perovskite phase, which is also a major component of Synroc, a titanate ceramic waste form used for sequestration of high-level waste (HLW) from reprocessed, spent nuclear fuel. This renewal project is based on the current needs in separation of cesium and strontium and the results obtained from our previous EMSP work. The purpose of this project is to deliver pertinent information that can be used to make rational decisions on selection of separation processes for cesium, strontium, and actinides. The objectives of this project are: (1) to establish the structure/property relationship between inorganic ion exchanger materials and their ability to selectively separate divalent cations under extreme operating conditions-This includes optimizing stoichiometry, synthesis, and pretreatment conditions for metal niobate and silicotitanate ion exchangers for maximum strontium and actinide-surrogate selectivity. (2) to fully characterize the phase relationships, structures, and thermodynamic and kinetic stabilities of these new phases and their related condensed phases (as potential ceramic waste forms) (3) to understand the chemical and thermodynamic stabilities of silicotitanate ion exchangers based on an in-depth comprehension of ...
Date: June 1, 2002
Creator: Su, Yali; Nenoff, Tina M. & Navrotsky, Alexandra
Partner: UNT Libraries Government Documents Department

New Metal Niobate and Silicotitanate Ion Exchangers: Development and Characterization

Description: This project is a continuing EMSP project entitled ''New Silicotitanate Waste Forms: Development and Characterization.'' In our original study, the phase selection and chemical durability of silicotitanates (including commercially available IE-911) as a function of temperature (500 to 1000 C) was fully characterized by a combination of techniques including XRD, TEM, SEM, NMR, Raman spectroscopy, XAFS, XANES, and by thermodynamic studies. In addition, work on this program led to new discoveries not anticipated in the originally proposed research. Of particular importance was the discovery of a new ion exchange material that is selective for divalent cations under extreme conditions (e.g., acid solutions, competing cations), thus providing an alternative for removing Sr from mixed wastes. This material is converted easily by high-temperature, in situ heat treatment into a perovskite phase, which is also a major component of Synroc, a titanate ceramic waste form used for sequestration of high-level waste (HLW) from reprocessed, spent nuclear fuel. This renewal project is based on the current needs in separation of cesium and strontium and the results obtained from our previous EMSP work. The purpose of this project is to deliver pertinent information that can be used to make rational decisions on selection of separation processes for cesium, strontium, and actinides. The objectives of this project are: (1) to establish the structure/property relationship between inorganic ion exchanger materials and their ability to selectively separate divalent cations under extreme operating conditions-This includes optimizing stoichiometry, synthesis, and pretreatment conditions for metal niobate and silicotitanate ion exchangers for maximum strontium and actinide-surrogate selectivity. (2) to fully characterize the phase relationships, structures, and thermodynamic and kinetic stabilities of these new phases and their related condensed phases (as potential ceramic waste forms) (3) to understand the chemical and thermodynamic stabilities of silicotitanate ion exchangers based on an in-depth comprehension of ...
Date: June 1, 2001
Creator: Su, Yali; Nenoff, Tina M. & Navrotsky, Alexandra
Partner: UNT Libraries Government Documents Department

New Metal Niobate and Silicotitanate Ion Exchangers: Development and Characterization

Description: This renewal proposal outlines our current progress and future research plans for ion exchangers: novel metal niobate and silicotitanate ion exchangers and their ultimate deployment in the DOE complex. In our original study several forms (including Cs exchanged) of the heat treated Crystalline Silicotitanates (CSTs) were fully characterized by a combination of high temperature synthesis and phase identification, low temperature synthesis and phase identification, and thermodynamics. This renewal proposal is predicated on work completed in our current EMSP program: we have shown preliminary data of a novel class of niobate-based molecular sieves (Na/Nb/M/O, M = transition metals), which show exceptionally high selectivity for divalent cations under extreme conditions (acid solutions, competing cations), in addition to novel silicotitanate phases which are also selective for divalent cations. Furthermore, these materials are easily converted by a high temperature in-situ heat treatment into a refractory ceramic waste form with low cation leachability. The new waste form is a perovskite phase, which is also a major component of Synroc, a titanate ceramic waste form used for sequestration of HLW wastes from reprocessed, spent nuclear fuel. These new niobate ion exchangers also shown orders of magnitude better selectivity for Sr2+ under acid conditions than any other material. The goal of the program is to reduce the costs associated with divalent cation waste removal and disposal, to minimize the risk of contamination to the environment during ion exchanger processing, and to provide DOE with materials for near-term lab-bench stimulant testing, and eventual deployment. The proposed work will provide information on the structure/property relationship between ion exchanger frameworks and selectivity for specific ions, allowing for the eventual ''tuning'' of framework for specific ion exchange needs. To date, DOE sites have become interested in on-site testing of these materials; ongoing discussions and initial experiments are occurring with Dr. Dean ...
Date: December 5, 2003
Creator: Navrotsky, Alexandra; Balmer, Mary Lou; Nenoff, Tina M. & Su, Yali
Partner: UNT Libraries Government Documents Department

Development, evaluation, and selection of candidate high-level waste forms

Description: The seven candidate waste forms, evaluated as potential media for the immobilization and gelogic disposal of high-level nuclear wastes were borosilicate glass, SYNROC, tailored ceramic, high-silica glass, FUETAP concrete, coated sol-gel particles, and glass marbles in a lead matrix. The evaluation, completed on August 1, 1981, combined preliminary waste form evaluations conducted at Department of Energy (DOE) defense waste-sites and at independent laboratories, peer review assessments, a product performance evaluation, and a processability analysis. Based on the combined results of these four inputs, two of the seven forms, borosilicate glass and a titanate-based ceramic, SYNROC, were selected as the reference and alternative forms, respectively, for continued development and evaluation in the National HLW Program. The borosilicate glass and ceramic forms were further compared during FY-1982 on the basis of risk assessments, cost comparisons, properties comparisons, and conformance with proposed regulatory and repository criteria. Both the glass and ceramic forms are viable candidates for use at DOE defense HLW sites; they are also candidates for immobilization of commercial reprocessing wastes. This paper describes the waste form screening process, discusses each of the four major inputs considered in the selection of the two forms in 1981, and presents a brief summary of the comparisons of the two forms during 1982 and the selection process to determine the final form for SRP defense HLW.
Date: January 1, 1982
Creator: Bernadzikowski, T A; Allender, J S; Gordon, D E & Gould, Jr, T H
Partner: UNT Libraries Government Documents Department

Sintering of Synroc D

Description: Sintering has been investigated as a method for the mineralization and densification of high-level nuclear defense waste powder. Studies have been conducted on Synroc D composite powder LS04. Optimal densification has been found to be highly dependent on the characteristics of the starting material. Powder subjected to milling, which was believed to reduce the level of agglomeration and possibly particle size, was found to densify better than powder not subjected to this milling. Densities of greater than 95% of theoretical could be achieved for samples sintered at 1150 to 1200/sup 0/C. Mineralogy was found to be as expected for Synroc D for samples sintered in a CO/sub 2//CO atmosphere where the Fe/sup +2//Fe/sup +3/ ratio was maintained at 1.0 to 5.75. In a more oxidizing, pure CO/sub 2/ atmosphere a new phase, not previously identified in Synroc D, was found.
Date: June 1, 1982
Creator: Robinson, G.
Partner: UNT Libraries Government Documents Department

Evaluation of Synroc-C as a second-generation waste form

Description: The durability of a crystalline titanate waste form, Synroc-C, was evaluated as a second-generation waste form by leach testing. Tests using both monolith and high surface area powdered samples were used with silicate water and brines at 90/sup 0/C and 150/sup 0/C for up to 90 days. In addition, low surface area-to-volume ratio, 1-day leach tests were conducted between 90/sup 0/C and 250/sup 0/C to determine forward-direction leach rates and activation energies. Dissolution rates of Cs, Mo, Ba, and U indicated that Synroc-C generally performed about an order of magntidue better than uranium-doped 76-68 glass. The release of Cs and Mo from Synroc-C, at least initially, may be primarily from intergranular regions of the material. The activation energy for the release of these elements from glass was about 9 kcal/mol but less than 3 kcal/mol for Synroc-C. In long-term tests, uranium dissolution may be controlled more by the formation of uranium alteration products than by release from the waste form.
Date: August 1, 1986
Creator: Shade, J.W.
Partner: UNT Libraries Government Documents Department

Support for DOE program in mineral waste-form development

Description: This research investigation relates to sintered simulation ceramic waste forms of the generic SYNROC compositional type. Though they have been formulated with simulated wastes only, they serve as prototypes for potential hot, processed, crystalline waste forms whose combined thermodynamic stability and physical integrity are considered to render them capable of long-term imobilization of high-level radwastes under deep geologic disposal conditions. The problems involved are nontrivial, largely because of the very complex nature of the radwastes: a typical waste stream would contain more than 31 cation species. When the stabilizing matrix constituents are included, the final batch composition must successfully account (and find substitutional homes for some 35 different cation species. One of the important objectives of this study thus has been to develop a computer-based method for simulating these complex ion substitutions, and for calculating the resultant phase demands and batch formulations. Primary goals of the study have been (1) use of that computer simulation capability to incorporate rationally the radwaste ions from a specific waste stream (PW-7a) into the available SYNROC lattice sites and (2) utilization of existing ceramic processing and sintering methodologies to assure (and to understand) the attainment of high density, fine microstructure, full phase development and other features of the sintered product which are known to relate directly to its integrity and leach resistance. Though improved resistance to leaching has been a continuing goal, time and budget constraints have precluded initiation of any leachability studies of these new compositions during this contract period. 27 references, 15 figures, 6 tables.
Date: September 1, 1982
Creator: Palmour, H. III; Hare, T.M.; Russ, J.C.; Batchelor, A.D.; Paisley, M.J. & Freed, L.E.
Partner: UNT Libraries Government Documents Department

Ceramic Hosts for Fission Products Immobilization

Description: Natural spinel, perovskite and zirconolite rank among the most leach resistant of mineral forms. They also have a strong affinity for a large number of other elements and including actinides. Specimens of natural perovskite and zirconolite were radioisotope dated and found to have survived at least 2 billion years of natural process while still remain their loading of uranium and thorium . Developers of the Synroc waste form recognized and exploited the capability of these minerals to securely immobilize TRU elements in high-level waste . However, the Synroc process requires a relatively uniform input and hot pressing equipment to produce the waste form. It is desirable to develop alternative approaches to fabricate these durable waste forms to immobilize the radioactive elements. One approach is using a high temperature process to synthesize these mineral host phases to incorporate the fission products in their crystalline structures. These mineral assemblages with immobilized fission products are then isolated in a durable high temperature glass for periods measured on a geologic time scale. This is a long term research concept and will begin with the laboratory synthesis of the pure spinel (MgAl2O4), perovskite (CaTiO3) and zirconolite (CaZrTi2O7) from their constituent oxides. High temperature furnace and/or thermal plasma will be used for the synthesis of these ceramic host phases. Nonradioactive strontium oxide will be doped into these ceramic phases to investigate the development of substitutional phases such as Mg1-xSrxAl2O4, Ca1-xSrxTiO3 and Ca1-xSrxZrTi2O7. X-ray diffraction will be used to establish the crystalline structures of the pure ceramic hosts and the substitution phases. Scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX) will be performed for product morphology and fission product surrogates distribution in the crystalline hosts. The range of strontium doping is planned to reach the full substitution of the divalent metal ions, Mg and Ca, in ...
Date: July 1, 2010
Creator: Kong, Peter C
Partner: UNT Libraries Government Documents Department

Basalt glass: an analogue for the evaluation of the long-term stability of nuclear waste form borosilicate glasses

Description: The long-term stability of nuclear waste form borosilicate glasses can be evaluated by understanding the processes that effect the long-term alteration of glass and by comparing laboratory alteration of synthetic basalt and borosilicate glasses with the observed stability of naturally occurring basaltic glasses in diverse geologic environments. This paper presents detailed electron microprobe analyses of naturally altered basaltic glasses (with maximum ages of 10,000 to 20 million years) from low-temperature environments. These results are compared to laboratory data on the corrosion of a synthetic basaltic glass in MCC-1 tests (90/sup 0/C, a SA/V of 0.1 cm/sup -1/ and time periods up to 182 days), MCC-2 tests (190/sup 0/C, a SA/V of 0.1 cm/sup -1/ and time periods up to 210 days) and hydration tests in saturated water vapor (240/sup 0/C, an estimated SA/V of approx. 10/sup 6/ cm/sup -1/ and time periods up to 63 days). Additionally, laboratory-induced hydration alteration of synthetic basalt and borosilicate glasses is compared. These preliminary experiments provide evidence that the alteration processes observed for natural basalt glasses are relevant to understanding the alteration of nuclear waste glass, as both appear to react via similar processes. 12 references, 6 figures, 1 table.
Date: January 1, 1984
Creator: Byers, C.D.; Jercinovic, M.J.; Ewing, R.C. & Keil, K.
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF GLASS AND CRYSTALLINE CERAMIC FORMS FOR DISPOSITION OF EXCESS PLUTONIUM

Description: In the aftermath of the Cold War, the United States Department of Energy (DOE) has identified up to 50 metric tons of excess plutonium that needs to be dispositioned. The bulk of the material is slated to be blended with uranium and fabricated into a Mixed Oxide (MOX) fuel for subsequent burning in commercial nuclear reactors. Excess plutonium-containing impurity materials making it unsuitable for fabrication into MOX fuel will need to be dispositioned via other means. Glass and crystalline ceramics have been developed and studied as candidate forms to immobilize these impure plutonium feeds. A titanate-based ceramic was identified as an excellent actinide material host. This composition was based on Synroc compositions previously developed for nuclear waste immobilization. These titanate ceramics were found to be able to accommodate extremely high quantities of fissile material and exhibit excellent aqueous durability. A lanthanide borosilicate (LaBS) glass was developed to accommodate high concentrations of plutonium and to be very tolerant of impurities yet still maintain good aqueous durability. Recent testing of alkali borosilicate compositions showed promise of using these compositions to disposition lower concentrations of plutonium using existing high level waste vitrification processes. The developed waste forms all appear to be suitable for Pu disposition. Depending on the actual types and concentrations of the Pu residue streams slated for disposition, each waste form offers unique advantages.
Date: September 10, 2009
Creator: Marra, James; Cozzi, A; Crawford, C.; Herman, C.; Marra, John & Peeler, D.
Partner: UNT Libraries Government Documents Department

Properties of SYNROC C nuclear-waste form: a state-of-the-art review

Description: SYNROC C is a titanate ceramic waste form designed to contain the waste generated by the reprocessing of commercial nuclear reactor fuel. The properties of SYNROC C are described with particular emphasis on the distribution of chemical elements in SYNROC, the fabrication of good quality specimens, and the chemical durability of SYNROC. Data obtained from testing of natural mineral analogues of SYNROC minerals are briefly discussed. The information available on radiation effects in SYNROC in relation to structural alteration and changes in chemical durability are summarized. 26 references, 2 figures, 18 tables.
Date: September 1, 1982
Creator: Oversby, V.M.
Partner: UNT Libraries Government Documents Department

Development of polyphase ceramics for the immobilization of high-level Defense nuclear waste

Description: The report contains two major sections: Section I - An Improved Polyphase Ceramic for High-Level Defense Nucleation Waste reports the work conducted on titanium-silica based ceramics for immobilizing Savannah River Plant waste. Section II - Formulation and Processing of Alumina Based Ceramic Nuclear Waste Forms describes the work conducted on developing a generic alumina and alumina-silica based ceramic waste form capable of immobilizing any nuclear waste with a high aluminum content. Such wastes include the Savannah River Plant wastes, Hanford neutralized purex wastes, and Hanford N-Reactor acid wastes. The design approach and process technology in the two reports demonstrate how the generic high waste loaded ceramic form can be applied to a broad range of nuclear waste compositions. The individual sections are abstracted and indexed separately.
Date: February 25, 1983
Creator: Morgan, P.E.D.; Harker, A.B.; Clarke, D.R.; Flintoff, J.J. & Shaw, T.M.
Partner: UNT Libraries Government Documents Department