60 research outputs found
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Elemental Composition of a Composite of Samples HTF-E-03-162 to 164 From Tank 51H to Evaluate Acceptability of the Sludge for Transfer to Tank 40H and Processing in the DWPF
Three dip samples of suspended sludge slurry were obtained from Tank 51H and sent to the Savannah River Technology Center for analysis. The composite of these samples is intended as a confirmatory sample to evaluate the acceptability of the Tank 51H sludge slurry for transfer to Tank 40H and for eventual processing in the Defense Waste Processing Facility. This report presents results of analyses requested by the Defense Waste Processing Facility for this evaluation. These analyses included the measurement of the concentrations of twenty two elements in the sludge slurry and the determination of the weight percent calcined solids of the slurry
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Leaching Tc-99 from SRP glass in simulated tuff and salt groundwaters
Results of leach tests with Tc-99 doped SRP borosilicate waste glass are presented. The glass was prepared by melting a mixture of SRP 165 powdered frit doped with a carrier free solution of Tc-99 at 1150{sup 0}C. Dissolution of portions of the resulting glass indicated that the Tc-99 was distributed homogeneously throughout the glass. Static leach tests up to 90 days were performed at 90{sup 0}C in J-13 tuff groundwater or WIPP brine A at a SA/V of 100m{sup -1}. Normalized mass losses were calculated for Tc-99 as well as all the major elements in the glass. Results indicated that under ambient oxidizing conditions Tc-99 leached no faster than the glass-forming elements of the glass. In J-13 water, Tc-99 leached congruently with B. In WIPP brine A, it leached congruently with Si. Leach rates for Li were higher in both groundwaters, probably due to a contribution from an ion exchange mechanism. Leach tests were performed under reducing conditions in J-13 water by adding Zn/Hg amalgam to the leachate. In these tests the pH increased significantly, probably because of the reaction of the amalgam with the water. In a 21-day test, the pH increased to 13 and leach rates for the glass were very high. Even though there was signifcant dissolution of the glass, the normalized mass loss based on Tc-99 was only 0.02g/m{sup 2}. This result and the fact that reducing conditions at normal pH values do not significantly affect the dissolution of the glass, indicate that the low concentrations for Tc-99 obtained under reducing conditions are due to is solubility and not due to an increased durability of the glass. 14 refs., 2 figs., 5 tabs
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Compositions and Durabilities of Glasses for Immobilization of Plutonium and Uranium
As the nuclear weapon arsenals of the United States and the Former Soviet Union are reduced, metric tonnage quantities of fissile material must be dispositioned. One of the potential disposition options for fissile weapons material is vitrification into a stable form -- essentially a plutonium or uranium single phase glass product. Savannah River Technology Center (SRTC) at Savannah River Site (SRS) is actively developing suitable glass formulations for the long term safe storage of plutonium and uranium. These investigations are also being extended to develop glasses for the stabilization and storage of kilogram amounts of neptunium, americium, and curium that are currently stored as solutions in the process canyons at SRS -- thus the glasses are called actinide glasses. SRTC is also in the process of developing a remote process demonstration which can produce metric tonnage quantities of the glasses. This paper discusses the chemical compositions and durabilities of two types of actinide glasses under development. One of the glasses is a borosilicate, and the other an iron phosphate. In this initial study thorium and uranium were used as the actinides. Because of the low radioactivity of these elements, the glasses could be prepared and tested on the bench top. In studies beginning in FY `95, glasses containing neptunium, plutonium, americium and curium will be produced. These glasses will be prepared and tested remotely in the shielded cells and glovebox facilities at Savannah River Technology Center. In the initial study, a considerable number (>20) of thorium and uranium bearing glasses have been prepared. An equivalent number of rare earth surrogate (non-radioactive) glasses have also been prepared and tested. The glasses were prepared by mixing dry chemicals and melting them at 1425C for the borosilicate glasses and at 1100C for the iron phosphate glasses. (Abstract Truncated
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Investigation of Sludge Batch 3 (Macrobatch 4) Glass Sample Anomalous Behavior
Two Defense Waste Processing Facility (DWPF) glass samples from Sludge Batch 3 (SB3) (Macrobatch 4) were received by the Savannah River National Laboratory (SRNL) on February 23, 2005. One sample, S02244, was designated for the Product Consistency Test (PCT) and elemental and radionuclide analyses. The second sample, S02247, was designated for archival storage. The samples were pulled from the melter pour stream during the feeding of Melter Feed Tank (MFT) Batch 308 and therefore roughly correspond to feed from Slurry Mix Evaporator (SME) Batches 306-308. During the course of preparing sample S02244 for PCT and other analyses two observations were made which were characterized as ''unusual'' or anomalous behavior relative to historical observations of glasses prepared for the PCT. These observations ultimately led to a series of scoping tests in order to determine more about the nature of the behavior and possible mechanisms. The first observation was the behavior of the ground glass fraction (-100 +200 mesh) for PCT analysis when contacted with deionized water during the washing phase of the PCT procedure. The behavior was analogous to that of an organic compound in the presence of water: clumping, floating on the water surface, and crawling up the beaker walls. In other words, the glass sample did not ''wet'' normally, displaying a hydrophobic behavior in water. This had never been seen before in 18 years SRNL PCT tests on either radioactive or non-radioactive glasses. Typical glass behavior is largely to settle to the bottom of the water filled beaker, though there may be suspended fines which result in some cloudiness to the wash water. The typical appearance is analogous to wetting sand. The second observation was the presence of faint black rings at the initial and final solution levels in the Teflon vessels used for the mixed acid digestion of S02244 glass conducted for compositional analysis. The digestion is composed of two stages, and at both the intermediate and the final content levels in the digestion vessel the rings were present. The rings had not been seen previously during glass digestions and were not present in the Analytical Reference Glass (ARG) standard samples digested, in separate vessels, along with the DWPF glass. What follows in this report are the results and analyses from various scoping experiments done in order to explain the anomalous behavior observed with DWPF glass S02244, along with a comparison with tests on sample S02247 where the anomalous wetting behavior was not observed
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Development of Alternative Glass Formulations for Vitrification of Excess Plutonium - SEM/XRD Analyses
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EVALUATION OF IMPURITY EXTREMES IN A PLUTONIUM-LOADED BOROSILICATE GLASS
A vitrification technology utilizing a lanthanide borosilicate (LaBS) glass appears to be a viable option for the disposition of excess weapons-useable plutonium that is not suitable for processing into mixed oxide (MOX) fuel. A significant effort to develop a glass formulation and vitrification process to immobilize plutonium was completed in the mid-1990s. The LaBS glass formulation was found to be capable of immobilizing in excess of 10 wt % Pu and to be tolerant of a range of impurities. To confirm the results of previous testing with surrogate Pu feeds containing impurities, four glass compositions were selected for fabrication with actual plutonium oxide and impurities. The four compositions represented extremes in impurity type and concentration. The homogeneity and durability of these four compositions were measured. The homogeneity of the glasses was evaluated using x-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). The XRD results indicated that the glasses were amorphous with no evidence of crystalline species in the glass. The SEM/EDS analyses did show the presence of some undissolved PuO{sub 2} material. The EDS spectra indicated that some of the PuO{sub 2} crystals also contained hafnium oxide. The SEM/EDS analyses showed that there were no heterogeneities in the glass due to the feed impurities. The durability of the glasses was measured using the Product Consistency Test (PCT). The PCT results indicated that the durability of Pu impurity glasses was comparable with Pu glasses without impurities and significantly more durable than the Environmental Assessment (EA) glass used as the benchmark for repository disposition of high-level waste (HLW) glasses
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Analytical Results of DWPF Glass Sample Taken During Filling of Canister S01913
The Defense Waste Processing Facility (DWPF) began processing Sludge Batch 2 (SB2) in December 2001 as part of Sludge Receipt and Adjustment Tank (SRAT) Batch 208. Sludge Batch 2 consists of the contents of Tank 40 and Tank 8 in approximately equal proportions. The sludge slurry is received into the DWPF Chemical Processing Cell and is processed through the SRAT and Slurry Mix Evaporator Tank. The treated sludge slurry is then transferred to the Melter Feed Tank and fed to the melter. During the processing of each sludge batch, the DWPF is required to take at least one glass sample. This glass sample is taken to meet the objectives of the Glass Product Control Program1 and to complete the necessary Production Records so that the final glass product may be disposed of at a Federal Repository.The DWPF requested analysis of a radioactive glass sample obtained from the melter pour stream during the processing of Macrobatch 3 (MB3) (Sludge Batch 2)2 with Frit 320. A glass sample was obtained while pouring Canister S01913 and was sent to the Savannah River National Laboratory Shielded Cells for characterization. Canister S01913 was the 267th canister poured during vitrification of Sludge Batch 2 (364 canisters of glass were prepared from SB2). The glass sample arrived from DWPF in primary container PC0034. The primary container contained pieces of glass. The glass had been extracted from the sample holder in the DWPF. This report contains the visual observations of the as-received glass sample, results for the density, the chemical composition, the Product Consistency Test and the calculated and measured radionuclide results needed for the Productio
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The product consistency test for the DWPF wasteform
The preliminary specifications on the glass wasteform to be produced by the Defense Waste Processing Facility (DWPF) require extensive characterization of the glass product both before actual production begins and then during production. To aid in this characterization, a leach test was needed that was easily reproducible, could be performed remotely on highly radioactive samples, and could yield results rapidly. Several standard leach tests were examined with a variety of test configurations. Using existing tests as a starting point, the DWPF Product Consistency Test (PCT) was developed in which crushed glass samples are exposed to 90{degrees}C deionized water for seven days. Based on extensive testing, including a seven-laboratory round robin and confirmatory testing with radioactive samples, the PCT is very reproducible, yields reliable results rapidly, and can be performed in shielded cell facilities with radioactive samples
Hydrogen Generation from α Radiolysis of Organic Materials in Transuranic Waste. Comparison Between Experimental Data and STORAGE Calculations
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