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1

Irradiation stability of R7T7-type borosilicate glass  

NASA Astrophysics Data System (ADS)

High-level nuclear waste containment glass is subjected to irradiation-induced stresses whose consequences must be assessed to guarantee the material behavior over time. Alpha decay from the minor actinides confined in the glass structure is responsible for most of the atom displacements. Minor actinide concentrations in the glass exceeding current levels are under consideration for future vitrification scenarios. Four R7T7-type borosilicate glass samples doped with 0.04, 0.4, 1.2 and 3.25 wt% 244CmO 2 were fabricated to study not only the cumulative effect of high alpha decay doses (>10 19 ?/g) but also of the dose rate. The homogeneity of the materials and their chemical compositions were characterized to ensure they were suitably representative for the experimental program. The macroscopic behavior of the glasses was characterized for doses up to 3 × 10 18 ?/g. No significant effect on the initial alteration rate was detected which means that the chemical reactivity of the glass with pure water is not affected by such levels of alpha doses. The glass swelled slightly depending on the dose, saturating at about 0.5% after receiving a dose of about 2 × 10 18 alpha disintegrations per gram of glass. The mechanical properties were observed to improve appreciably, with lower hardness but greater fracture toughness. A stabilization phenomenon comparable to that of the glass density was also observed. Comparing the experimental data with other findings obtained by atomistic modeling and external irradiation suggests that nuclear interactions caused by alpha decay recoil nuclei could be responsible for the experimental variations observed. The possible origins of the observed variations in macroscopic properties are also discussed.

Peuget, S.; Cachia, J.-N.; Jégou, C.; Deschanels, X.; Roudil, D.; Broudic, V.; Delaye, J. M.; Bart, J.-M.

2006-08-01

2

Helium mobility in SON68 borosilicate nuclear glass: A nuclear reaction analysis approach  

NASA Astrophysics Data System (ADS)

The 3He behavior in the non active R7T7 type borosilicate glass called SON68 has been investigated using the implantation method to introduce helium in the material. Nuclear Reaction Analysis (NRA) was performed to follow the helium concentration depth profile evolution as a function of annealing time and temperature. In addition, in situ Transmission Electron Microscopy (TEM) has been implemented to study the formation of helium bubbles during both implantation and annealing processes. Numerical modeling with two different approaches is proposed and discussed to investigate the helium mobility mechanisms. Our study reveals for helium incorporation by implantation at low temperature the presence of several helium populations with disparate diffusivities. The most mobile helium fraction would be attributed to atomic diffusion. The corresponding activation energy value (0.61 eV) extracted from Arrhenius graphs is in good agreement with literature data. The results also highlight that the damages associated to helium sursaturation are the source of small helium clusters formation, with a reduced mobility instead of the atomic mobility measured by the infusion technique. Small cavities that support this assumption have been observed by TEM at low temperature.

Bès, R.; Sauvage, T.; Peuget, S.; Haussy, J.; Chamssedine, F.; Oliviero, E.; Fares, T.; Vincent, L.

2013-11-01

3

SON 68 nuclear glass alteration kinetics between pH 7 and pH 11.5  

NASA Astrophysics Data System (ADS)

The effect of the pH was investigated on the mechanisms of SON 68 (R7T7-type) glass alteration under `saturation' conditions in order to delimit the pH range within which a stable, protective gel is formed. Static experiments were conducted at 90°C with an S/ V ratio of 50 cm-1 at various imposed pH values: 7, 8, 9.5, 10, 10.5, 11 and 11.5. An additional experiment was conducted with no restriction on the pH. The kinetic study showed that a protective gel formed in all the test media, although its stability was pH-dependent: at pH 11 or higher, the precipitation of a potassium and sodium aluminosilicate led to the degradation of the gel and the lose of its protective properties. This phenomenon resulted in renewed glass alteration, leading to complete and rapid degradation of the glass into alteration products. The aluminosilicate precipitation was found to be limited by the solubility of aluminum. Below pH 10, this type of secondary phase is unlikely to precipitate and the gel should remain stable. This study, based on thermodynamic and kinetic considerations, suggests that aqueous alteration of the French SON 68 nuclear glass results in the formation of a protective gel with long-term stability between pH 7 and pH 10.

Gin, S.; Mestre, J. P.

2001-05-01

4

Dissolution mechanism of the SON68 reference nuclear waste glass: New data in dynamic system in silica saturation conditions  

NASA Astrophysics Data System (ADS)

The alteration of SON68 glass (inactive R7T7 type nuclear waste glass) was studied to measure the long-term residual dissolution rate under different conditions. Experiments were conducted in flow-through conditions (solution flow rate 3-5 mL/day) at pH 8.0, 9.5, and 10.5 under various initial Si concentrations, a glass surface-to-volume ratio near 14,000 m -1 and at a temperature of 90 °C. This set of long-term experiments (200 days) showed leaching rates dependent on the initial silica concentration and the initial pH. Interpretation of results at pH 8.0 was difficult due to the use of a synthetic water used to represent waters found at a potential French repository site. Because very small glass powder sizes were used (Ø = 1 ?m), a complete dissolution of the pristine glass was achieved at low initial silica concentrations where higher leaching rates were produced. In all cases, initial high normalized leaching rates were observed followed by a decrease in leaching rate with rate levels ranging from 9 (±4) to 5 (±3) × 10 -4 g m -2 d -1 at 200 days under silica saturated conditions at pH 9.5 and 10.5, respectively. We have compared these results to previous results obtained in similar leaching conditions. Modeling using the GM2004 model program and model output values were shown to be in agreement with experimental results.

Neeway, J.; Abdelouas, A.; Grambow, B.; Schumacher, S.

2011-08-01

5

Natural analogues of nuclear waste glass corrosion.  

SciTech Connect

This report reviews and summarizes studies performed to characterize the products and processes involved in the corrosion of natural glasses. Studies are also reviewed and evaluated on how well the corrosion of natural glasses in natural environments serves as an analogue for the corrosion of high-level radioactive waste glasses in an engineered geologic disposal system. A wide range of natural and experimental corrosion studies has been performed on three major groups of natural glasses: tektite, obsidian, and basalt. Studies of the corrosion of natural glass attempt to characterize both the nature of alteration products and the reaction kinetics. Information available on natural glass was then compared to corresponding information on the corrosion of nuclear waste glasses, specifically to resolve two key questions: (1) whether one or more natural glasses behave similarly to nuclear waste glasses in laboratory tests, and (2) how these similarities can be used to support projections of the long-term corrosion of nuclear waste glasses. The corrosion behavior of basaltic glasses was most similar to that of nuclear waste glasses, but the corrosion of tektite and obsidian glasses involves certain processes that also occur during the corrosion of nuclear waste glasses. The reactions and processes that control basalt glass dissolution are similar to those that are important in nuclear waste glass dissolution. The key reaction of the overall corrosion mechanism is network hydrolysis, which eventually breaks down the glass network structure that remains after the initial ion-exchange and diffusion processes. This review also highlights some unresolved issues related to the application of an analogue approach to predicting long-term behavior of nuclear waste glass corrosion, such as discrepancies between experimental and field-based estimates of kinetic parameters for basaltic glasses.

Abrajano, T.A. Jr.; Ebert, W.L.; Luo, J.S.

1999-01-06

6

Systems approach to nuclear waste glass development  

SciTech Connect

Development of a host solid for the immobilization of nuclear waste has focused on various vitreous wasteforms. The systems approach requires that parameters affecting product performance and processing be considered simultaneously. Application of the systems approach indicates that borosilicate glasses are, overall, the most suitable glasses for the immobilization of nuclear waste. Phosphate glasses are highly durable; but the glass melts are highly corrosive and the glasses have poor thermal stability and low solubility for many waste components. High-silica glasses have good chemical durability, thermal stability, and mechanical stability, but the associated high melting temperatures increase volatilization of hazardous species in the waste. Borosilicate glasses are chemically durable and are stable both thermally and mechanically. The borosilicate melts are generally less corrosive than commercial glasses, and the melt temperature miimizes excessive volatility of hazardous species. Optimization of borosilicate waste glass formulations has led to their acceptance as the reference nuclear wasteform in the United States, United Kingdom, Belgium, Germany, France, Sweden, Switzerland, and Japan.

Jantzen, C M

1986-01-01

7

Extrapolation of nuclear waste glass aging  

SciTech Connect

Increased confidence is provided to the extrapolation of long-term waste form behavior by comparing the alteration of experimentally aged natural basaltic glass to the condition of the same glass as it has been geologically aged. The similarity between the laboratory and geologic alterations indicates that important aging variables have been identified and incorporated into the laboratory experiments. This provides credibility to the long-term predictions made for waste form borosilicate glasses using similar experimental procedures. In addition, these experiments have demonstrated that the aging processes for natural basaltic glass are relevant to the alteration of nuclear waste glasses, as both appear to react via similar processes. The alteration of a synthetic basaltic glass was measured in MCC-1 tests done at 90/sup 0/C, a SA/V of 0.1 cm/sup -1/ and time periods up to 182 days. Tests were also done using (1) MCC-2 procedures at 190/sup 0/C, a SA/V of 0.1 cm/sup -1/ and time periods up to 91 days and (2) hydration tests in saturated water vapor at 240/sup 0/C, a SA/V of approx. 10/sup 6/ cm/sup -1/, and time periods up to 63 days. These results are compared to alteration observed in natural basaltic glasses of great age. 6 references, 6 figures, 1 table.

Byers, C.D.; Ewing, R.C.; Jercinovic, M.J.; Keil, K.

1984-01-01

8

Glass produced by underground nuclear explosions. [Rainier  

SciTech Connect

Detonation of an underground nuclear explosive produces a strong shock wave which propagates spherically outward, vaporizing the explosive and nearby rock and melting, the surrounding rock. The vaporized material expands adiabatically, forming a cavity. As the energy is dissipated during the cavity formation process, the explosive and rock debris condense and mix with the melted rock. The melt flows to the bottom of the cavity where it is quenched by fractured rock fragments falling from above as the cavity collapses. Measurements indicate that about 740 tonnes of rock and/or soil are melted for every kiloton (10/sup 12/ calories) of explosive energy, or about 25% of the explosive energy goes to melting rock. The resulting glass composition reflects the composition of the unaltered rock with explosive debris. The appearance ranges from white pumice to dense, dark lava. The bulk composition and color vary with the amount of explosive iron incorporated into the glass. The refractory explosion products are mixed with the solidified melt, although the degree of mixing is variable. Electron microprobe studies of glasses produced by Rainier in welded tuff have produced the following results: glasses are dehydrated relative to the host media, glasses are extremely heterogeneous on a 20 ..mu..m scale, a ubiquitous feature is the presence of dark marble-cake regions in the glass, which were locally enriched in iron and may be related to the debris, optically amorphous regions provide evidence of shock melting, only limited major element redistribution and homogenization occur within the cavity.

Schwartz, L.; Piwinskii, A.; Ryerson, F.; Tewes, H.; Beiriger, W.

1983-01-01

9

Factors influencing chemical durability of nuclear waste glasses  

SciTech Connect

A short summary is given of our studies on the major factors that affect the chemical durability of nuclear waste glasses. These factors include glass composition, solution composition, SA/V (ratio of glass surface area to the volume of solution), radiation, and colloidal formation. These investigations have enabled us to gain a better understanding of the chemical durability of nuclear waste glasses and to accumulate.a data base for modeling the long-term durability of waste glass, which will be used in the risk assessment of nuclear waste disposal. This knowledge gained also enhances our ability to formulate optimal waste glass compositions.

Feng, Xiangdong; Bates, J.K.

1993-01-01

10

Factors influencing chemical durability of nuclear waste glasses  

SciTech Connect

A short summary is given of our studies on the major factors that affect the chemical durability of nuclear waste glasses. These factors include glass composition, solution composition, SA/V (ratio of glass surface area to the volume of solution), radiation, and colloidal formation. These investigations have enabled us to gain a better understanding of the chemical durability of nuclear waste glasses and to accumulate.a data base for modeling the long-term durability of waste glass, which will be used in the risk assessment of nuclear waste disposal. This knowledge gained also enhances our ability to formulate optimal waste glass compositions.

Feng, Xiangdong; Bates, J.K.

1993-03-01

11

Effects of some glass additives on nuclear waste glass durability in water  

Microsoft Academic Search

Borosilicate glass is a candidate material for immobilizing high-level waste (HLW) stemming from the reprocessing of spent fuels used for nuclear power generation. The borosilicate glass containing HLW, which is called HLW glass, will be stored on the land surface for several tens of years and then disposed of in deep geologic formations. The contact of HLW glass with ground

H. Kamizono; I. Hayakawa; S. Muraoka

1991-01-01

12

Thermodynamic model of natural, medieval and nuclear waste glass durability  

SciTech Connect

A thermodynamic model of glass durability based on hydration of structural units has been applied to natural glass, medieval window glasses, and glasses containing nuclear waste. The relative durability predicted from the calculated thermodynamics correlates directly with the experimentally observed release of structural silicon in the leaching solution in short-term laboratory tests. By choosing natural glasses and ancient glasses whose long-term performance is known, and which bracket the durability of waste glasses, the long-term stability of nuclear waste glasses can be interpolated among these materials. The current Savannah River defense waste glass formulation is as durable as natural basalt from the Hanford Reservation (10/sup 6/ years old). The thermodynamic hydration energy is shown to be related to the bond energetics of the glass. 69 references, 2 figures, 1 table.

Jantzen, C.M.; Plodinec, M.J.

1983-01-01

13

Hydration process of nuclear-waste glass: an interim report  

SciTech Connect

Aging of simulated nuclear waste glass by contact with a controlled-temperature, humid atmosphere results in the formation of a double hydration layer penetrating the glass, as well as the formation of minerals on the glass surface. The hydration process can be described by Arrhenius behavior between 120 and 240/sup 0/C. Results suggest that simulated aging reactions are necessary for demonstrating that nuclear waste forms can meet projected Nuclear Regulatory Commission regulations. 16 figures, 4 tables.

Bates, J.K.; Jardine, L.J.; Steindler, M.J.

1982-07-01

14

Nuclear waste glass Product Consistency Test (PCT), Version 3. 0  

Microsoft Academic Search

Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. The glass will be produced in the Defense Waste Processing Facility (DWPF), poured into stainless steel canisters, and eventually disposed of in a geologic repository. In order to comply with the Waste Acceptance Preliminary Specifications (WAPS), the durability of the glass needs

C. M. Jantzen; N. E. Bibler

1990-01-01

15

Nuclear waste glass product consistency test (PCT), Version 5. 0  

Microsoft Academic Search

Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. The glass will be produced in the Defense Waste Processing Facility (DWPF), poured into stainless steel canisters, and eventually disposed of in a geologic repository. In order to comply with the Waste Acceptance Preliminary Specifications (WAPS), the durability of the glass needs

C. M. Jantzen; N. E. Bibler; D. C. Beam; W. G. Ramsey; B. J. Waters

1992-01-01

16

Compositional threshold for Nuclear Waste Glass Durability  

SciTech Connect

Within the composition space of glasses, a distinct threshold appears to exist that separates "good" glasses, i.e., those which are sufficiently durable, from "bad" glasses of a low durability. The objective of our research is to clarify the origin of this threshold by exploring the relationship between glass composition, glass structure and chemical durability around the threshold region.

Kruger, Albert A. [Pacific Northwest National Lab., Richland, WA (United States); Farooqi, Rahmatullah [Pohang Univ. of Science and Technology, (Korea, Republic of); Hrma, Pavel R. [Pacific Northwest National Lab., Richland, WA (United States), Pohang Univ. of Science and Technology, (Korea, Republic of)

2013-04-24

17

Chemical durability of simulated nuclear glasses containing water  

SciTech Connect

The chemical durability of simulated nuclear waste glasses having different water contents was studied. Results from the product consistency test (PCT) showed that glass dissolution increased with water content in the glass. This trend was not observed during MCC-1 testing. This difference was attributed to the differences in reactions between glass and water. In the PCT, the glass network dissolution controlled the elemental releases, and water in the glass accelerated the reaction rate. On the other hand, alkali ion exchange with hydronium played an important role in the MCC-1. For the latter, the amount of water introduced into a leached layer from ion-exchange was found to be much greater than that of initially incorporated water in the glass. Hence, the initial water content has no effect on glass dissolution as measured by the MCC-1 test.

Li, H. [Pacific Northwest Lab., Richland, WA (United States); Tomozawa, M. [Rensselaer Polytechnic Inst., Troy, New York (United States)

1995-04-01

18

Natural analogues of nuclear waste glass corrosion  

Microsoft Academic Search

This report reviews and summarizes studies performed to characterize the products and processes involved in the corrosion of natural glasses. Studies are also reviewed and evaluated on how well the corrosion of natural glasses in natural environments serves as an analogue for the corrosion of high-level radioactive waste glasses in an engineered geologic disposal system. A wide range of natural

T. A. Jr. Abrajano; W. L. Ebert; J. S. Luo

1999-01-01

19

Control of Nepheline Crystallization in Nuclear Waste Glass  

SciTech Connect

Glass frits with a high B{sub 2}O{sub 3} concentration have been designed which, when combined with high-alumina concentration nuclear waste streams, will form glasses with durabilities that are acceptable for repository disposal and predictable using a free energy of hydration model. Two glasses with nepheline discriminator values closest to 0.62 showed significant differences in normalized boron release between the quenched and heat treated versions of each glass. X-ray diffraction confirmed that nepheline crystallized in the glass with the lowest nepheline discriminator value, and nepheline may also exist in the second glass as small nanocrystals. The high-B{sub 2}O{sub 3} frit was successful in producing simulated waste glasses with no detectable nepheline crystallization at waste loadings of up to 45 wt%. The melt rate of this frit was also considerably better than other frits with increased concentrations of Na{sub 2}O.

Fox, Kevin

2008-07-01

20

Hydrogen speciation in hydrated layers on nuclear waste glass  

SciTech Connect

The hydration of an outer layer on nuclear waste glasses is known to occur during leaching, but the actual speciation of hydrogen (as water or hydroxyl groups) in these layers has not been determined. As part of the Nevada Nuclear Waste Storage Investigations Project, we have used infrared spectroscopy to determine hydrogen speciations in three nuclear waste glass compositions (SRL-131 & 165, and PNL 76-68), which were leached at 90{sup 0}C (all glasses) or hydrated in a vapor-saturated atmosphere at 202{sup 0}C (SRL-131 only). Hydroxyl groups were found in the surface layers of all the glasses. Molecular water was found in the surface of SRL-131 and PNL 76-68 glasses that had been leached for several months in deionized water, and in the vapor-hydrated sample. The water/hydroxyl ratio increases with increasing reaction time; molecular water makes up most of the hydrogen in the thick reaction layers on vapor-phase hydrated glass while only hydroxyl occurs in the least reacted samples. Using the known molar absorptivities of water and hydroxyl in silica-rich glass the vapor-phase layer contained 4.8 moles/liter of molecular water, and 0.6 moles water in the form hydroxyl. A 15 {mu}m layer on SRL-131 glass formed by leaching at 90{sup 0}C contained a total of 4.9 moles/liter of water, 2/3 of which was as hydroxyl. The unreacted bulk glass contains about 0.018 moles/liter water, all as hydroxyl. The amount of hydrogen added to the SRL-131 glass was about 70% of the original Na + Li content, not the 300% that would result from alkali=hydronium ion interdiffusion. If all the hydrogen is then assumed to be added as the result of alkali-H{sup +} interdiffusion, the molecular water observed may have formed from condensation of the original hydroxyl groups.

Aines, R.D.; Weed, H.C.; Bates, J.K.

1987-01-15

21

Immobilization of spent nuclear fuel in iron phosphate glass  

NASA Astrophysics Data System (ADS)

Twenty-four iron phosphate compositions (15 wt% wasteloading) were evaluated to determine their suitability for vitrifying Al-clad, highly enriched uranium, spent nuclear fuel (SNF). In half the compositions melted, 80 wt% of the Al 2O 3 in the simulated SNF was removed prior to vitrification. All twenty-four compositions formed homogeneous glasses, many at temperatures as low as 1150°C. As little as 2.5 wt% Na 2O decreased melt viscosity and increased alumina solubility in those glasses of higher alumina contents (7.2 wt% Al 2O 3). None of the glasses contained undissolved uranium compounds as has been found in borosilicate glasses containing as little 4.4 wt% UO 2. The chemical durability (measured by the product consistency test (PCT)) of the iron phosphate wasteforms is as good as, and in many cases up to 15 times better than the approved reference material (ARM-1) borosilicate glass.

Mesko, M. G.; Day, D. E.

22

Natural glass analogues to alteration of nuclear waste glass: A review and recommendations for further study  

SciTech Connect

The purpose of this report is to review previous work on the weathering of natural glasses; and to make recommendations for further work with respect to studying the alteration of natural glasses as it relates quantifying rates of dissolution. the first task was greatly simplified by the published papers of Jercinovic and Ewing (1987) and Byers, Jercinovic, and Ewing (1987). The second task is obviously the more difficult of the two and the author makes no claim of completeness in this regard. Glasses weather in the natural environment by reacting with aqueous solutions producing a rind of secondary solid phases. It had been proposed by some workers that the thickness of this rind is a function of the age of the glass and thus could be used to estimate glass dissolution rates. However, Jercinovic and Ewing (1987) point out that in general the rind thickness does not correlate with the age of the glass owing to the differences in time of contact with the solution compared to the actual age of the sample. It should be noted that the rate of glass dissolution is also a function of the composition of both the glass and the solution, and the temperature. Quantification of the effects of these parameters (as well as time of contact with the aqueous phase and flow rates) would thus permit a prediction of the consequences of glass-fluid interactions under varying environmental conditions. Defense high- level nuclear waste (DHLW), consisting primarily of liquid and sludge, will be encapsulated by and dispersed in a borosilicate glass before permanent storage in a HLW repository. This glass containing the DHLW serves to dilute the radionuclides and to retard their dispersion into the environment. 318 refs.

McKenzie, W.F.

1990-01-01

23

Durabiliy of two simulated nuclear waste glasses, a frit glass, and tektite in aqueous solutions: Final report, Volume I  

SciTech Connect

High level nuclear waste is commonly incorporated into glass for disposal. Therefore the long term aqueous durability of the waste glass is important. The leaching behavior of three simulated nuclear waste glasses (AH10, AH165, and Frit 165) and a natural glass (tektite) were examined using nuclear reaction analysis, leachate solution analysis, and microscopy. The three simulated waste glasses developed hydrated layers which increased in thickness by t/sup /1/2//. The hydrated layer in Frit 165 reached a constant thickness of about one micron. Alkali were preferentially removed from the Frit 165 and AH10. The tektite corroded by slow uniform dissolution. 94 refs., 68 figs., 13 tabs.

Hagen, D.A.; Altstetter, C.J.; Brown, S.D.

1988-05-01

24

Spectroscopic investigations on glasses, glass-ceramics and ceramics developed for nuclear waste immobilization  

NASA Astrophysics Data System (ADS)

Highly radioactive nuclear waste must be immobilized in very durable matrices such as glasses, glass-ceramics and ceramics in order to avoid their dispersion in the biosphere during their radioactivity decay. In this paper, we present various examples of spectroscopic investigations (optical absorption, Raman, NMR, EPR) performed to study the local structure of different kinds of such matrices used or envisaged to immobilize different kinds of radioactive wastes. A particular attention has been paid on the incorporation and the structural role of rare earths—both as fission products and actinide surrogates—in silicate glasses and glass-ceramics. An example of structural study by EPR of a ceramic (hollandite) irradiated by electrons (to simulate the effect of the ?-irradiation of radioactive cesium) is also presented.

Caurant, D.

2014-05-01

25

Redox reaction and foaming in nuclear waste glass melting  

SciTech Connect

This document was prepared by Pacific Northwest Laboratory (PNL) and is an attempt to analyze and estimate the effects of feed composition variables and reducing agent variables on the expected chemistry of reactions occurring in the cold cap and in the glass melt in the nuclear waste glass Slurry-fed, joule-heated melters as they might affect foaming during the glass-making process. Numerous redox reactions of waste glass components and potential feed additives, and the effects of other feed variables on these reactions are reviewed with regard to their potential effect on glass foaming. A major emphasis of this report is to examine the potential positive or negative aspects of adjusting feed with formic acid as opposed to other feed modification techniques including but not limited to use of other reducing agents. Feed modification techniques other than the use of reductants that should influence foaming behavior include control of glass melter feed pH through use of nitric acid. They also include partial replacement of sodium salts by lithium salts. This latter action (b) apparently lowers glass viscosity and raises surface tension. This replacement should decrease foaming by decreasing foam stability.

Ryan, J.L.

1995-08-01

26

Helium solubility in SON68 nuclear waste glass  

SciTech Connect

Helium behavior in a sodium borosilicate glass (SON68) dedicated to the immobilization of high-level nuclear waste is examined. Two experimental approaches on nonradioactive glass specimens are implemented: pressurized helium infusion experiments and {sup 3}He ion implantation experiments. The temperature variation of helium solubility in SON68 glass was determined and analyzed with the harmonic oscillator model to determine values of the energy of interaction E(0) at the host sites (about -4000 J/mol), the vibration frequency (about 1.7 x 10{sup 11} s{sup -1}), and the density of solubility sites (2.2 x 10{sup 21} sites cm{sup -3}). The implantation experiments show that a non diffusive transport phenomenon (i.e., athermal diffusion) is involved in the material when the helium concentration exceeds 2.3 x 10{sup 21} He cm{sup -3}, and thus probably as soon as it exceeds the density of solubility sites accessible to helium in the glass. We propose that this transport mechanism could be associated with the relaxation of the stress gradient induced by the implanted helium profile, which is favored by the glass damage. Microstructural characterization by TEM and ESEM of glass specimens implanted with high helium concentrations showed a homogeneous microstructure free of bubbles, pores, or cracking at a scale of 10 nm. (authors)

Fares, Toby; Peuget, Sylvain; Bouty, Olivier; Broudic, Veronique; Maugeri, Emilio; Bes, Rene; Jegou, Christophe [CEA, DEN, DTCD SECM LMPA, F-30207 Marcoule, Bagnols Sur Cez, (France); Chamssedine, Fadel; Sauvage, Thierry [CNRS, CEMHTI, F-245071 Orleans, (France); Deschanels, Xavier [LNAR, Marcoule Inst Separat Chem, F-30207 Bagnols Sur Ceze, (France)

2012-12-15

27

Resumption of nuclear glass alteration: State of the art  

NASA Astrophysics Data System (ADS)

Studies of nuclear glass alteration kinetics have shown that after the beginning of a rate drop due to the approach of silica saturation of the solution and the formation of a passivating layer, a resumption of alteration is possible. This phenomenon corresponding to an acceleration of the glass dissolution rate is systematically associated with the precipitation of zeolites and, to a lesser extent, calcium silicate hydrates. Secondary phases which precipitate from the major glass network-forming elements (Si, Al) strongly impact the dissolution kinetics. The literature data are generally consistent and the results are reproducible, showing that the resumption of alteration is observed at high pH, temperature, and S/V ratio during laboratory experiments. The studies also show that the resumption of alteration is strongly dependent on the composition of the glass and the leaching solutions. The wide range of glass compositions studied (about 60 glasses in the articles reviewed) and the variable test conditions (temperature, pH, and solution composition) make it extremely difficult to compare and compile the data, or to decorrelate the effects of the composition on the time before the resumption of alteration and on its magnitude. The observations to date have led to a proposed macroscopic mechanism based on the loss of the passivating properties of the alteration layer after consumption of a fraction of the network-forming elements by precipitation of zeolites. No multiscale mechanistic approach exists, however, to account for the nucleation and growth of zeolites at the expense of the glass. For example, the effect of aluminum in the gel or in solution on the glass alteration kinetics is not sufficiently understood today. Although thermodynamic models have been proposed to delimit the ranges of glass compositions subject to a resumption of alteration, their development is hampered by inadequate knowledge of the newly formed phases and their nucleation-growth mechanism, and by gaps in the thermodynamic databases. Their development is also constrained by the capability of the models to take Si-Al-Ca interactions into account in the alteration gels.

Fournier, Maxime; Gin, Stéphane; Frugier, Pierre

2014-05-01

28

MILLIMETER-WAVE MONITORING OF NUCLEAR WASTE GLASS MELTS - AN OVERVIEW  

EPA Science Inventory

Molten glass characteristics of temperature, resistivity, and viscosity can be monitored reliably in the high temperature and chemically corrosive environment of nuclear waste glass melters using millimeter-wave sensor technology. Millimeter-waves are ideally suited for such meas...

29

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

SciTech Connect

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.

Byers, C.D.; Jercinovic, M.J.; Ewing, R.C.; Keil, K.

1984-01-01

30

Nuclear waste glass product consistency test (PCT), Version 5.0. Revision 2  

Microsoft Academic Search

Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. The glass will be produced in the Defense Waste Processing Facility (DWPF), poured into stainless steel canisters, and eventually disposed of in a geologic repository. In order to comply with the Waste Acceptance Preliminary Specifications (WAPS), the durability of the glass needs

C. M. Jantzen; N. E. Bibler; D. C. Beam; W. G. Ramsey; B. J. Waters

1992-01-01

31

Nuclear waste glass product consistency test (PCT): Version 7.0. Revision 3  

Microsoft Academic Search

Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. The glass will be produced in the Defense Waste Processing Facility (DWPF), poured into stainless steel canisters, and eventually disposed of in a geologic repository. In order to comply with the Waste Acceptance Product Specifications (WAPS), the durability of the glass needs

C. M. Jantzen; N. E. Bibler; D. C. Beam; W. G. Ramsey

1994-01-01

32

Solubility interpretations of leach tests on nuclear waste glass  

SciTech Connect

A one-year leach test at 90/sup 0/C was conducted on specimens of PNL 76-68 borosilicate glass, a simulated nuclear waste glass. The experimental method was MCC-1, one of the standard leach tests developed by the Materials Characterization Center (MCC). The leachant solutions included deionized water, a silicic acid/sodium bicarbonate solution, and a concentrated K-Mg-Na-Cl brine. Phase characterization techniques and geochemical codes were used to identify possible solubility and sorption controls for the constituents dissolved in the final leach solutions. In the non-brine solutions, an alteration layer of 30-50 ..mu..m is formed that consists mainly of an amorphous Fe(OH)/sub 3/. In addition, a zinc silicate phase precipitated on the glass surface and appears to control the concentrations of dissolved Cs and Si. Calculations with the MINTEQ geochemical code identified possible equilbrium solubility controls for dissolved Fe, Ca, Si, Zn, Pb, P, and F. These calculations also permitted an estimation of the pH at the temperature of the leach experiments. The PHREEQE geochemical code was used to predict the steady state concentrations of Ca/sup 2 +/ and Sr/sup 2 +/ in the final leachates by assuming their sorption on solid amorphous Fe(OH)/sub 3/. For the leach tests completed in the brine solution, a magnesium silicate phase precipitated on the glass surface and may have been responsible for the observed decrease in the concentration of the dissolved Si. This solid phase was tentatively identified as sepiolite and/or possibly talc. These results were compared to mineral solubilities calculated from the MINTEQ geochemical code.

Strachan, D.M.; Krupka, K.M.

1984-01-01

33

Lead iron phosphate glass as a containment medium for disposal of high-level nuclear waste  

DOEpatents

Lead-iron phosphate glasses containing a high level of Fe.sub.2 O.sub.3 for use as a storage medium for high-level radioactive nuclear waste. By combining lead-iron phosphate glass with various types of simulated high-level nuclear waste, a highly corrosion resistant, homogeneous, easily processed glass can be formed. For corroding solutions at 90.degree. C., with solution pH values in the range between 5 and 9, the corrosion rate of the lead-iron phosphate nuclear waste glass is at least 10.sup.2 to 10.sup.3 times lower than the corrosion rate of a comparable borosilicate nuclear waste glass. The presence of Fe.sub.2 O.sub.3 in forming the lead-iron phosphate glass is critical. Lead-iron phosphate nuclear waste glass can be prepared at temperatures as low as 800.degree. C., since they exhibit very low melt viscosities in the 800.degree. to 1050.degree. C. temperature range. These waste-loaded glasses do not readily devitrify at temperatures as high as 550.degree. C. and are not adversely affected by large doses of gamma radiation in H.sub.2 O at 135.degree. C. The lead-iron phosphate waste glasses can be prepared with minimal modification of the technology developed for processing borosilicate glass nuclear wasteforms.

Boatner, Lynn A. (Oak Ridge, TN); Sales, Brian C. (Oak Ridge, TN)

1989-01-01

34

Development of glass vitrification at SRL as a waste treatment technique for nuclear weapon components  

SciTech Connect

This report discusses the development of vitrification for the waste treatment of nuclear weapons components at the Savannah River Site. Preliminary testing of surrogate nuclear weapon electronic waste shows that glass vitrification is a viable, robust treatment method.

Coleman, J.T.; Bickford, D.F.

1991-12-31

35

Development of glass vitrification at SRL as a waste treatment technique for nuclear weapon components  

SciTech Connect

This report discusses the development of vitrification for the waste treatment of nuclear weapons components at the Savannah River Site. Preliminary testing of surrogate nuclear weapon electronic waste shows that glass vitrification is a viable, robust treatment method.

Coleman, J.T.; Bickford, D.F.

1991-01-01

36

Final technical report: Effects of water on properties of the simulated nuclear waste glasses  

SciTech Connect

For isolation of nuclear wastes through the vitrification process, waste slurry is mixed with borosilicate based glass and remelted at high temperature. During these processes, water can enter into the final waste glass. It is known that water in silica and silicate glasses changes various glass properties, such as chemical durability, viscosity and electrical conductivity. These properties are very important for processing and assuring the quality and safety controls of the waste glasses. The objective of this project was to investigate the effect of water in the simulated nuclear waste glasses on various glass properties, including chemical durability, glass transition temperature, liquidus temperature, viscosity and electrical conductivity. This report summarizes the results of this investigation conducted at Rensselaer during the past one year.

Li, H.; Tomozawa, M.

1996-02-01

37

Glass former composition and method for immobilizing nuclear waste using the same  

DOEpatents

An alkoxide glass former composition has silica-containing constituents present as solid particulates of a particle size of 0.1 to 0.7 micrometers in diameter in a liquid carrier phase substantially free of dissolved silica. The glass former slurry is resistant to coagulation and may contain other glass former metal constituents. The immobilization of nuclear waste employs the described glass former by heating the same to reduce the volume, mixing the same with the waste, and melting the resultant mixture to encapsulate the waste in the resultant glass.

Cadoff, Laurence H. (Wilkins Township, Allegheny County, PA); Smith-Magowan, David B. (Washington, DC)

1988-01-01

38

Structural analysis of some sodium and alumina rich high-level nuclear waste glasses  

SciTech Connect

Sodium and aluminum rich high level nuclear waste glasses are prone to nepheline (NaAlSiO4) crystallization. Since nepheline removes three moles of glass forming oxides (Al2O3 and SiO2) per each mole of Na2O, its formation can result in sever deterioration of the chemical durability. The present study aims at investigating the relationships between the molecular-level structure of sodium alumino-borosilicate based simulated high-level nuclear waste glasses and their crystallization behavior by infrared spectroscopy (FTIR) and x-ray diffraction, respectively. The molecular structure of most of the investigated glasses comprises of a mixture of Q2 and Q3 (Si) units while aluminum and boron are predominantly present in tetrahedral and trigonal coordination, respectively. The increasing boron content has been shown to suppress the nepheline formation in the glasses. The structural influence of various glass components on nepheline crystallization has been discussed.

Goel, Ashutosh; McCloy, John S.; Fox, Kevin M.; Leslie, Clifford J.; Riley, Brian J.; Rodriguez, Carmen P.; Schweiger, Michael J.

2012-02-01

39

Nano-Continuum Modeling of a Nuclear Glass Specimen Altered for 25 Years  

SciTech Connect

The purpose of this contribution is to report on preliminary nano-continuum scale modeling of nuclear waste glass corrosion. The focus of the modeling is an experiment involving a French glass SON68 specimen leached for 25 years in a granitic environment. In this report, we focus on capturing the nano-scale concentration profiles. We use a high resolution continuum model with a constant grid spacing of 1 nanometer to investigate the glass corrosion mechanisms.

Steefel, Carl

2014-01-06

40

Nuclear Physics A 757 (2005) 127 Quarkgluon plasma and color glass condensate at  

E-print Network

Nuclear Physics A 757 (2005) 1­27 Quark­gluon plasma and color glass condensate at RHIC:10.1016/j.nuclphysa.2005.02.130 #12;2 I. Arsene et al. / Nuclear Physics A 757 (2005) 1­27 Abstract Institut de Recherches Subatomiques et Université Louis Pasteur, Strasbourg, France c Institute of Nuclear

41

ALKALI/ AKALINE-EARTH CONTENT EFFECTS ON PROPERTIES OF HIGH-ALUMINA NUCLEAR WASTE GLASSES  

SciTech Connect

A series of high alumina (>20 mass %) borosilicate glasses have been made and characterized based on the assumption that the primary modifier cation field strength plays a significant role in mediating glass structure of nuclear waste glasses. Any crystallization upon quenching or after heat treatment at 950 °C for 24 hours was identified and quantified by X-ray diffraction. Particular note was take of any aluminosilicates formed, such as those in the nepheline group (MAlSiO4 where M=K, Na, Li), as these remove multiple glass-formers from the network upon crystallization. The relative roles of potassium, sodium, lithium, calcium, and magnesium on glass structure and crystallization in high alumina glasses were explored using Raman and infrared vibrational spectroscopy. Strong evidence was found for the importance of 4 membered rings in glasses with 10 mol % alkaline earths (Ca, Mg).

McCloy, John S.; Rodriguez, Carmen P.; Windisch, Charles F.; Leslie, Clifford J.; Schweiger, Michael J.; Riley, Brian J.; Vienna, John D.

2010-10-01

42

Performing a chemical durability test on radioactive high-level nuclear waste glass  

Microsoft Academic Search

Savannah River Site (SRS), currently is storing â¼30 million gallons of highly radioactive nuclear wastes. The Defense Waste Processing Facility (DWPF) nearing completion at SRS will incorporate the radionuclides in these wastes into solid borosilicate glass for final disposal in a geologic repository. Because of the variability of the wastes in the tanks, borosilicate glasses of different compositions will be

D. C. Beam; J. A. Napier; J. D. McCurry; N. E. Bibler

1990-01-01

43

ASSESSMENT OF NEPHELINE PRECIPITATION IN NUCLEAR WASTE GLASS VIA THERMOCHEMICAL MODELING  

EPA Science Inventory

A thermochemical representation of the Na-Al-Si-B-O system relevant for nuclear waste glass has been developed based on the associate species approach for the glass solution phase. Thermochemical data were assessed and associate species data determined for binary and ternary sub...

44

Cerium, uranium, and plutonium behavior in glass-bonded sodalite, a ceramic nuclear waste form  

Microsoft Academic Search

Glass-bonded sodalite is being developed as a ceramic waste form (CWF) to immobilize radioactive fission products, actinides, and salt residues from electrometallurgical treatment of spent nuclear reactor fuel. The CWF consists of about 75 mass% sodalite, 25 mass% glass, and small amounts of other phases. This paper presents some results and interpretation of physical measurements to characterize the CWF structure,

L. R. Morss; M. A. Lewis; M. K. Richmann; D. Lexa

2000-01-01

45

The effect of chromium oxide on the properties of simulated nuclear waste glasses  

SciTech Connect

A study of the effect of chromium on the properties of selected glasses was performed in the frame of a Contract between Battelle, Pacific Northwest Laboratories and Nuclear Research Institute, ReZ. In the period from July 1994 to June 1995 two borosilicate glasses of special composition were prepared according to the PNL procedure and their physical and structural characteristics of glasses were studied. This Final Report contains a vast documentation on the properties of all glasses studied. For the preparation of the respective technology more detailed study of physico-chemical properties and crystallinity of investigated systems would be desirable.

Vojtech, O.; Sussmilch, J.; Urbanec, Z. [and others

1996-02-01

46

Leaching behavior of glass ceramic nuclear waste forms  

SciTech Connect

Glass ceramic waste forms have been investigated as alternatives to borosilicate glasses for the immobilization of high-level radioactive waste at Pacific Northwest Laboratory (PNL). Three glass ceramic systems were investigated, including basalt, celsian, and fresnoite, each containing 20 wt % simulated high-level waste calcine. Static leach tests were performed on seven glass ceramic materials and one parent glass (before recrystallization). Samples were leached at 90/sup 0/C for 3 to 28 days in deionized water and silicate water. The results, expressed in normalized elemental mass loss, (g/m/sup 2/), show comparable releases from celsian and fresnoite glass ceramics. Basalt glass ceramics demonstrated the lowest normalized elemental losses with a nominal release less than 2 g/m/sup 2/ when leached in polypropylene containers. The releases from basalt glass ceramics when leached in silicate water were nearly identical with those in deionized water. The overall leachability of celsian and fresnoite glass ceramics was improved when silicate water was used as the leachant.

Lokken, R.O.

1981-11-01

47

West Valley high-level nuclear waste glass development: a statistically designed mixture study  

SciTech Connect

The first full-scale conversion of high-level commercial nuclear wastes to glass in the United States will be conducted at West Valley, New York, by West Valley Nuclear Services Company, Inc. (WVNS), for the US Department of Energy. Pacific Northwest Laboratory (PNL) is supporting WVNS in the design of the glass-making process and the chemical formulation of the glass. This report describes the statistically designed study performed by PNL to develop the glass composition recommended for use at West Valley. The recommended glass contains 28 wt% waste, as limited by process requirements. The waste loading and the silica content (45 wt%) are similar to those in previously developed waste glasses; however, the new formulation contains more calcium and less boron. A series of tests verified that the increased calcium results in improved chemical durability and does not adversely affect the other modeled properties. The optimization study assessed the effects of seven oxide components on glass properties. Over 100 melts combining the seven components into a wide variety of statistically chosen compositions were tested. Viscosity, electrical conductivity, thermal expansion, crystallinity, and chemical durability were measured and empirically modeled as a function of the glass composition. The mathematical models were then used to predict the optimum formulation. This glass was tested and adjusted to arrive at the final composition recommended for use at West Valley. 56 references, 49 figures, 18 tables.

Chick, L.A.; Bowen, W.M.; Lokken, R.O.; Wald, J.W.; Bunnell, L.R.; Strachan, D.M.

1984-10-01

48

Physical and chemical characteristics of lead-iron phosphate nuclear waste glasses  

SciTech Connect

Experimental determinations of the properties of lead-iron phosphate glasses pertinent to their application to the problem of permanently disposing of high-level nuclear wastes have been carried out. These investigations included studies of the composition and physical properties of nuclear waste glasses (NWG), as well as the effect of preparation conditions. Lead-iron phosphate nuclear waste glasses were prepared by dissolving simulated US defense wastes or simulated commercial power reactor wastes in molten lead-iron phosphate melts at temperatures between 900 and 1050/sup 0/C. The measured physical and chemical properties of the nuclear waste glasses formed by cooling these melts and annealing included the following: (1) aqueous corrosion resistance as a function of the solution pH, solution temperature, and glass composition, (2) glass density, (3) thermal expansion coefficient, (4) glass transition temperature and softening point, (5) heat capacity, (6) critical cooling rate, (7) temperature for the maximum crystallization rate, (8) relative solubility of waste oxides in the glass melt, (9) reactions between the molten glass and the melting crucible (Pt, ZrO/sub 2/, Al/sub 2/O/sub 3/), and (10 studies of possible metal cannister materials. Experimental results for the lead-iron phosphate NWG are compared to available data for borosilicate NWG. Relative to borosilicate NWG, the lead-iron phosphate glasses have several distinct advantages which include a much lower aqueous corrosion rate, a lower preparation temperature, and the ability to immobilize many types of commercial and defense-related high-level radioactive wastes. 34 refs., 18 figs., 10 tabs.

Sales, B.C.; Boatner, L.A.

1985-05-01

49

Effects of Large Nuclear Quadrupoles on Dielectric Properties of Glasses at Very Low Temperatures  

NASA Astrophysics Data System (ADS)

The universal behaviour of amorphous solids at low temperatures, governed by atomic tunneling systems as described by the standard tunneling model, has long been a generally accepted fact. In the last years, however, measurements of dielectric two-pulse polarization echoes have revealed that nuclear quadrupole moments involved in atomic tunneling systems can cause specific material-dependent effects in magnetic fields. We have performed measurements of the dielectric properties of the two multicomponent glasses N-KZFS11 and HY-1, containing several percent of tantalum oxide and holmium oxide respectively. As 181Ta and 165Ho both carry very large nuclear quadrupole moments, these glasses are ideal candidates to study the influence of nuclear quadrupole moments on the properties of glasses at very low temperatures. Our measurements not only show unique dielectric behaviour in both glasses, but also differ significantly from various predictions of the standard tunneling model.

Luck, A.; Fleischmann, A.; Reiser, A.; Enss, C.

2014-12-01

50

Nuclear waste disposal: alternatives to solidification in glass proposed  

Microsoft Academic Search

More than a quarter-million cubic meters of liquid radioactive wastes are now being held at government installations awaiting final disposal. During the past 20 years, the disposal plan of choice has been to incorporate the 40 to 50 radioactive elements dissolved in liquid wastes into blocks of glass, seal the glass in metal canisters, and insert the canisters into deep,

R. A. KERR

1979-01-01

51

Simulation of Self-Irradiation of High-Sodium Content Nuclear Waste Glasses  

SciTech Connect

Alkali-borosilicate glasses are widely used in nuclear industry as a matrix for immobilisation of hazardous radioactive wastes. Durability or corrosion resistance of these glasses is one of key parameters in waste storage and disposal safety. It is influenced by many factors such as composition of glass and surrounding media, temperature, time and so on. As these glasses contain radioactive elements most of their properties including corrosion resistance are also impacted by self-irradiation. The effect of external gamma-irradiation on the short-term (up to 27 days) dissolution of waste borosilicate glasses at moderate temperatures (30 deg. to 60 deg. C) was studied. The glasses studied were Magnox Waste glass used for immobilisation of HLW in UK, and K-26 glass used in Russia for ILW immobilisation. Glass samples were irradiated under {gamma}-source (Co-60) up to doses 1 and 11 MGy. Normalised rates of elemental release and activation energy of release were measured for Na, Li, Ca, Mg, B, Si and Mo before and after irradiation. Irradiation up to 1 MGy results in increase of leaching rate of almost all elements from both MW and K-26 with the exception of Na release from MW glass. Further irradiation up to a dose of 11 MGy leads to the decrease of elemental release rates to nearly initial value. Another effect of irradiation is increase of activation energies of elemental release. (authors)

Pankov, Alexey S.; Ojovan, Michael I. [Immobilisation Science Laboratory, Department of Engineering Materials, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD (United Kingdom); Batyukhnova, Olga G. [International Education Training Centre, SUE SIA 'Radon', The 7-th Rostovsky Lane 2/14, Moscow, 119121 (Russian Federation); Lee, William E. [Department of Materials, Imperial College London, South Kensington Campus, Exhibition Road, London, SW7 2AZ (United Kingdom)

2007-07-01

52

THE IMPACT OF KINETICS ON NEPHELINE FORMATION IN NUCLEAR WASTE GLASSES  

SciTech Connect

Sixteen glass compositions were selected to study the potential impacts of the kinetics of nepheline formation in high-level nuclear waste (HLW) glass. The chosen compositions encompassed a relatively large nepheline discriminator (ND) range, 0.40-0.66, and included a relatively broad range, and amount of, constituents including high aluminum and high boron concentrations. All glasses were fabricated in the laboratory and subsequently exposed to six different cooling treatments. The cooling treatments consisted of three 'stepped' profiles and their corresponding 'smooth' profiles. Included in the cooling treatment was the Defense Waste Processing Facility (DWPF) canister centerline cooling (CCC) profile in addition to a 'faster' and a 'slower' total cooling line. After quenching and heat treating, x-ray diffraction confirmed the type and amount of any resultant crystallization. The target compositions were shown to be consistent with the measured compositions. Two quenched glasses and several treated glasses exhibited minor amounts of spinel and spinel-like phases. Nepheline was not observed in any of the quenched glasses but was observed in many of the treated glasses. The amount of nepheline ranged from approximately 2wt% to 30wt% for samples cooled over shorter times and longer times respectively. Differences were observed in the amount of nepheline crystallization after smooth and stepped cooling and increased with total cooling time. In some glasses, nepheline crystallization appeared to be directly proportional to total cooling time while the total amount of nepheline crystallization varied, suggesting that the nepheline crystallization rate was independent of (or at least faster than) cooling rate but, varied depending on the glass composition. On the contrary, in another glass, nepheline crystallization appeared to be inversely proportional to cooling rate. The high alumina glasses, predicted to form nepheline according to the ND, did not precipitate nepheline. Additionally, analysis from different regions of treated glasses indicated that nepheline nucleation and growth occurs at the glass/crucible and glass/atmosphere interfaces. Furthermore, the measured amount of non-nepheline phases appeared independent of the sampling region. It is postulated that crucible-scale methods used to heat treat HLW glass, such as the CCC method, artificially induce nepheline formation in the glass. The results of this study suggest nepheline kinetics can vary significantly depending on glass composition and, more importantly, glasses fabricated using current DWPF conditions are potentially susceptible to the impact of nepheline kinetics. This report summarizes the supporting research and provides the basis for continued research on nepheline kinetics and its effects on HLW glasses.

Amoroso, J.

2011-03-07

53

Use of DWPF redox measurement technique on glasses from West Valley Nuclear Fuel Services Demonstration Project  

SciTech Connect

Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass in the Defense Waste Processing Facility (DWPF). A similar vitrification facility exists at the West Valley Nuclear Fuel Services. In both of these facilities, control of the oxidation/reduction (redox) equilibrium in the glass melter is critical for processing of the nuclear waste. Redox can be determined by measuring the ratio of ferrous to ferric ions in the glass melt. A colorimetric procedure has been developed for the DWPF which has been shown to give rapid and reliable analytical results. This colorimetric technique has been shown to measure the Fe{sup 2+} component of glasses more accurately than other existing redox measurement methods. The DWPF redox technique was applied to a series of six glasses taken from the West Valley melter during a transient melter excursion. This excursion caused the glasses to become progressively more reducing with time. Application of the DWPF redox technique to these glasses correctly indicated the redox trends with a higher precision and with more accuracy than the West Valley wet chemical method and/or Alfred University's Mossbauer method. 1 fig., 18 refs.

Jantzen, C.M.

1990-10-01

54

EELS Spectrum Imaging and Tomography Studies of Simulated Nuclear Waste Glasses  

SciTech Connect

Electron energy loss spectroscopy (EELS) fine structure is a powerful technique for analyzing oxidation levels of rare-earth oxides and coordination numbers in glasses and ceramics, especially for boron. To exploit the unique advantage of EELS over x-ray absorption spectroscopy (XAS)/x-ray absorption near edge structure (XANES), namely nm-scale spatial resolution, EELS spectrum imaging across precipitates in glasses has been employed to detect lateral changes of EELS fine structure. Alkali borosilicate (ABS) glasses doped with Cr{sub 2}O{sub 3}, CeO{sub 2} and ZrO{sub 2} or Fe{sub 2}O{sub 3} were melted to simulate high level radionuclide immobilization glasses. Precipitates with diameter in the range of {approx}20 nm to {approx}500 nm were found homogeneously distributed in the glasses. Ce valence was found to be mainly +3 in the glass matrix, and +4 in crystalline precipitates, while some amorphous particles show +3 as well. Another powerful TEM technique for the analysis of glass-nano-composites is electron tomography, as it is up to now the only technique for the three-dimensional reconstruction of nano-particles. A 3D reconstructed nuclear waste glass is presented in this paper by using a tilt series of ADF STEM images covering a glass fragment of {approx}3{mu}m field of view containing several tens of nano-particles distributed throughout its volume. (authors)

Yang, Guang; Saghi, Zineb; Xu, Xiaojing; Hand, Russell; Moebus, Guenter [Engineering Materials, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD (United Kingdom)

2007-07-01

55

Spectroscopic investigation of gamma radiation-induced coloration in silicate glass for nuclear applications  

NASA Astrophysics Data System (ADS)

Silicate glass irradiated by ?-rays was investigated in this study using spectroscopic analyses which included ultraviolet-visible (UV-Vis) absorption, electron paramagnetic resonance (EPR), and nuclear magnetic resonance (NMR). The phenomenon of coloration on ?-ray-irradiated silicate glass was analyzed and the effect of annealing on the silicate coloration was also investigated. The results revealed that the coloration originates from the creation of hole-centers (HC) caused by radiation. The shade of the coloration highly correlates to the amount of these HC-related defects but can be reversed by thermal annealing. The variation in coloration is an effective predictive factor in understanding radiation damage on silicate glass. Therefore, this study is relevant in the development of radiation detectors using silicate material as well as in the permanent disposal of high-level nuclear waste in glass form.

Tsai, Hsu-Sheng; Chao, Der-Sheng; Wu, Ya-Hsuan; He, Yu-Ting; Chueh, Yu-Lun; Liang, Jenq-Horng

2014-10-01

56

Progress toward bridging from atomistic to continuum modeling to predict nuclear waste glass dissolution.  

SciTech Connect

This report summarizes research performed for the Nuclear Energy Advanced Modeling and Simulation (NEAMS) Subcontinuum and Upscaling Task. The work conducted focused on developing a roadmap to include molecular scale, mechanistic information in continuum-scale models of nuclear waste glass dissolution. This information is derived from molecular-scale modeling efforts that are validated through comparison with experimental data. In addition to developing a master plan to incorporate a subcontinuum mechanistic understanding of glass dissolution into continuum models, methods were developed to generate constitutive dissolution rate expressions from quantum calculations, force field models were selected to generate multicomponent glass structures and gel layers, classical molecular modeling was used to study diffusion through nanopores analogous to those in the interfacial gel layer, and a micro-continuum model (K{mu}C) was developed to study coupled diffusion and reaction at the glass-gel-solution interface.

Zapol, Peter (Argonne National Laboratory, Argonne, IL); Bourg, Ian (Lawrence Berkeley National Laboratories, Berkeley, CA); Criscenti, Louise Jacqueline; Steefel, Carl I. (Lawrence Berkeley National Laboratories, Berkeley, CA); Schultz, Peter Andrew

2011-10-01

57

Effects of composition on properties in an 11-component nuclear waste glass system  

SciTech Connect

Ninety simplified nuclear waste glass compositions within an 11-component oxide composition matrix were tested for crystallinity, viscosity, volatility, and chemical durability. Empirical models of property response as a function of glass composition were developed using statistical experimental design and modeling techniques. A new statistical technique was developed to calculate the effects of oxide components on each property. Independent melts were used to check the prediction accuracy of the models.

Chick, L.A.; Piepel, G.F.; Mellinger, G.B.; May, R.P.; Gray, W.J.; Buckwalter, C.Q.

1981-09-01

58

Deformation mechanisms during nanoindentation of sodium borosilicate glasses of nuclear interest.  

PubMed

In this paper we analyze results of Molecular Dynamics simulations of Vickers nanoindentation, performed for sodium borosilicate glasses of interest in the nuclear industry. Three glasses have been studied in their pristine form, as well as a disordered one that is analogous to the real irradiated glass. We focused in the behavior of the glass during the nanoindentation in order to reveal the mechanisms of deformation and how they are affected by microstructural characteristics. Results have shown a strong dependence on the SiO2 content of the glass, which promotes densification due to the open structure of SiO4 tetrahedra and also due to the strength of Si-O bonds. Densification for the glasses is primarily expressed by the relative decrease of the Si-O-Si and Si-O-B angles, indicating rotation of the structural units and decrease of free volume. The increase of alkali content on the other hand results to higher plasticity of the matrix and increased shear flow. The most important effect on the deformation mechanism of the disordered glasses is that of the highly depolymerized network that will also induce shear flow and, in combination with the increased free volume, will result in the decreased hardness of these glasses, as has been previously observed. PMID:25005296

Kilymis, D A; Delaye, J-M

2014-07-01

59

AN APPROACH TO THERMOCHEMICAL MODELING OF NUCLEAR WASTE GLASS  

EPA Science Inventory

This initial work is aimed at developing a basic understanding of the phase equilibria and solid solution behavior of the constituents of waste glass. Current, experimentally determined values are less than desirable since they depend on measurement of the leach rate under non-r...

60

Solid-State NMR Examination of Alteration Layers on a Nuclear Waste Glasses  

SciTech Connect

Solid-state NMR is a powerful tool for probing the role and significance of alteration layers in determining the kinetics for the corrosion of nuclear waste glass. NMR methods are used to probe the chemical structure of the alteration layers to elucidate information about their chemical complexity, leading to increased insight into the mechanism of altered layer formation. Two glass compositions were examined in this study: a glass preliminarily designed for nuclear waste immobilization (called AFCI) and a simplified version of this AFCI glass (which we call SA1R). Powdered glasses with controlled and known particles sizes were corroded at 90 °C for periods of one and five months with a surface-area to solution-volume ratio of 100,000 m-1. 1H-29Si CP-CPMG MAS NMR, 1H-27Al CP-MAS NMR, 1H-11B CP-MAS NMR, and 1H-23Na CP-MAS NMR experiments provide isolated structural information about the alteration layers, which differ in structure from that of the pristine glass. Both glasses studied here develop alteration layers composed primarily of [IV]Si species. Aluminum is also retained in the alteration layers, perhaps facilitated by the observed increase in coordination from [IV]Al to [VI]Al, which correlates with a loss of charge balancing cations. 1H-11B CP-MAS NMR observations indicated a retention of boron in hydrated glass layers, which has not been characterized by previous work. For the AFCI glass, secondary phase formation begins during the corrosion times considered here, and these neophases are detected within the alteration layers. We identify precursor phases as crystalline sodium metasilicates. An important finding is that layer thickness depends on the length of the initial alteration stages and varies only with respect to silicon species during the residual rate regime.

Murphy, Kelly A. [Penn State Univ., State College, PA (United States). Dept. of Chemistry; Washton, Nancy M. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Science Lab.; Ryan, Joseph V. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Pantano, Carlo G. [Penn State Univ., State College, PA (United States). Dept. of Materials Science and Engineering; Mueller, Karl T. [Penn State Univ., State College, PA (United States). Dept. of Chemistry; Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Science Lab.

2013-06-01

61

AN ALTERNATIVE HOST MATRIX BASED ON IRON PHOSPHATE GLASSES FOR THE VITRIFICATION OF SPECIALIZED NUCLEAR WASTE FORMS  

EPA Science Inventory

Borosilicate glass is the only material currently approved and being used to vitrify high level nuclear waste. Unfortunately, many high level nuclear waste feeds in the U.S. contain components which are chemically incompatible with borosilicate glasses. Current plans call for vit...

62

Lead-iron phosphate glass as a containment medium for the disposal of high-level nuclear wastes  

DOEpatents

Disclosed are lead-iron phosphate glasses containing a high level of Fe/sub 2/O/sub 3/ for use as a storage medium for high-level radioactive nuclear waste. By combining lead-iron phosphate glass with various types of simulated high-level nuclear waste

Boatner, L.A.; Sales, B.C.

1984-04-11

63

Rhenium solubility in borosilicate nuclear waste glass: implications for the processing and immobilization of technetium-99.  

PubMed

The immobilization of technetium-99 ((99)Tc) in a suitable host matrix has proven to be a challenging task for researchers in the nuclear waste community around the world. In this context, the present work reports on the solubility and retention of rhenium, a nonradioactive surrogate for (99)Tc, in a sodium borosilicate glass. Glasses containing target Re concentrations from 0 to 10,000 ppm [by mass, added as KReO(4) (Re(7+))] were synthesized in vacuum-sealed quartz ampules to minimize the loss of Re from volatilization during melting at 1000 °C. The rhenium was found as Re(7+) in all of the glasses as observed by X-ray absorption near-edge structure. The solubility of Re in borosilicate glasses was determined to be ~3000 ppm (by mass) using inductively coupled plasma optical emission spectroscopy. At higher rhenium concentrations, additional rhenium was retained in the glasses as crystalline inclusions of alkali perrhenates detected with X-ray diffraction. Since (99)Tc concentrations in a glass waste form are predicted to be <10 ppm (by mass), these Re results implied that the solubility should not be a limiting factor in processing radioactive wastes, assuming Tc as Tc(7+) and similarities between Re(7+) and Tc(7+) behavior in this glass system. PMID:23101883

McCloy, John S; Riley, Brian J; Goel, Ashutosh; Liezers, Martin; Schweiger, Michael J; Rodriguez, Carmen P; Hrma, Pavel; Kim, Dong-Sang; Lukens, Wayne W; Kruger, Albert A

2012-11-20

64

Comprehensive data base of high-level nuclear waste glasses: September 1987 status report: Volume 1, Discussion and glass durability data  

SciTech Connect

The Materials Characterization Center (MCC) at Pacific Northwest Laboratory is assembling a comprehensive data base (CDB) of experimental data collected for high-level nuclear waste package components. Data collected throughout the world are included in the data base; current emphasis is on waste glasses and their properties. The goal is to provide a data base of properties and compositions and an analysis of dominant property trends as a function of composition. This data base is a resource that nuclear waste producers, disposers, and regulators can use to compare properties of a particular high-level nuclear waste glass product with the properties of other glasses of similar compositions. Researchers may use the data base to guide experimental tests to fill gaps in the available knowledge or to refine empirical models. The data are incorporated into a computerized data base that will allow the data to be extracted based on, for example, glass composition or test duration. 3 figs.

Kindle, C.H.; Kreiter, M.R.

1987-12-01

65

Low-temperature lithium diffusion in simulated high-level boroaluminosilicate nuclear waste glasses  

SciTech Connect

Ion exchange is recognized as an integral, if underrepresented, mechanism influencing glass corrosion. However, due to the formation of various alteration layers in the presence of water, it is difficult to conclusively deconvolute the mechanisms of ion exchange from other processes occurring simultaneously during corrosion. In this work, an operationally inert non-aqueous solution was used as an alkali source material to isolate ion exchange and study the solid-state diffusion of lithium. Specifically, the experiments involved contacting glass coupons relevant to the immobilization of high-level nuclear waste, SON68 and CJ-6, which contained Li in natural isotope abundance, with a non-aqueous solution of 6LiCl dissolved in dimethyl sulfoxide at 90 °C for various time periods. The depth profiles of major elements in the glass coupons were measured using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Lithium interdiffusion coefficients, DLi, were then calculated based on the measured depth profiles. The results indicate that the penetration of 6Li is rapid in both glasses with the simplified CJ-6 glass (D6Li ? 4.0-8.0 × 10-21 m2/s) exhibiting faster exchange than the more complex SON68 glass (D6Li ? 2.0-4.0 × 10-21 m2/s). Additionally, sodium ions present in the glass were observed to participate in ion exchange reactions; however, different diffusion coefficients were necessary to fit the diffusion profiles of the two alkali ions. Implications of the diffusion coefficients obtained in the absence of alteration layers to the long-term performance of nuclear waste glasses in a geological repository system are also discussed.

Neeway, James J.; Kerisit, Sebastien N.; Gin, Stephane; Wang, Zhaoying; Zhu, Zihua; Ryan, Joseph V.

2014-12-01

66

Thermal and physicochemical properties important for the long term behavior of nuclear waste glasses  

NASA Astrophysics Data System (ADS)

High level nuclear waste from reprocessing of spent nuclear fuel has to be solidified in a stable matrix for safe long-time storage. Vitrification in borosilicate glasses is the technique accepted worldwide as the best combination of engineering constraints from fabrication and physicochemical properties of the matrix. A number of different glasses was developed in different national programs. The criteria and the reasons for selecting the final compositions are described briefly. Emphasis is placed on the French product R7T7 and on thermal and physicochemical properties though glasses developed in other national projects (e.g., the German product GP 98/12, etc.) are also treated. The basic physical and mechanical properties and the chemical durability of the glass in contact with water are described. The basic mechanisms of aqueous corrosion are discussed and the evolving modelling of the leaching process is dealt with, as well as effects of container material, backfill, etc. The thermal behavior has also been studied and extensive data exist on diffusion of glass constituents (Na) and of interesting elements of the waste such as the alkalis Rb and Cs or the actinides U and Pu, as well as on crystallization processes in the glass during storage at elevated temperatures. Emphasis is placed on the radiation stability of the glasses, based on extensive studies using short-lived actinides (e.g., 244Cm) or ion implantation to produce the damage expected during long storage at an accelerated rate. The radiation stability is shown to be very good, if realistic damage conditions are used. The knowledge accumulated in the past years is used to evaluate and predict the long-term evolution of the glass under storage conditions.

Matzke, Hj.; Vernaz, E.

67

The use of self heating'' ceramics as crucibles for microwave melting metals and nuclear waste glass  

SciTech Connect

Silicon carbide (SiC) crucibles were used to melt aluminum and copper in conventional and tuned microwave cavities at a microwave frequency of 2450 MHz. SiC crucibles were also used to vitrify and homogenize mixtures of nuclear waste and glass frit.

Sturcken, E.F.

1990-01-01

68

The use of ``self heating`` ceramics as crucibles for microwave melting metals and nuclear waste glass  

SciTech Connect

Silicon carbide (SiC) crucibles were used to melt aluminum and copper in conventional and tuned microwave cavities at a microwave frequency of 2450 MHz. SiC crucibles were also used to vitrify and homogenize mixtures of nuclear waste and glass frit.

Sturcken, E.F.

1990-12-31

69

ANNUAL PROGRESS REPORT. IRON PHOSPHATE GLASSES: AN ALTERNATIVE FOR VITRIFYING CERTAIN NUCLEAR WASTES  

EPA Science Inventory

A high priority has been given to investigating the vitrification of three specific nuclear wastes in iron phosphate glasses (IPG). These wastes, which were recommended by the Tank Focus Area (TFA) group of Hanford, are poorly suited for vitrification in the currently DOE-approve...

70

High-level nuclear waste borosilicate glass: A compendium of characteristics  

Microsoft Academic Search

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

J. C. Cunnane; J. K. Bates; W. L. Ebert; X. Feng; J. J. Mazer; D. J. Wronkiewicz; J. Sproull; W. L. Bourcier; B. P. McGrail

1992-01-01

71

Chemical interaction between a simulated nuclear waste glass and different backfill materials under a thermal gradient  

Microsoft Academic Search

The initial stage of a HLW disposal will be dominated by a strong thermal gradient that will exist between the hot canister and the “cold” geological medium. In the case of hot wastes (MOx, direct disposal of used spent fuel, short interim storage), nuclear glass can begin to dissolve in groundwater and to interact with other materials in the presence

Christophe Poinssot; Pierre Toulhoat; Bruno Goffé

1998-01-01

72

Standard test methods for determining chemical durability of nuclear, hazardous, and mixed waste glasses and multiphase glass ceramics: The product consistency test (PCT)  

E-print Network

1.1 These product consistency test methods A and B evaluate the chemical durability of homogeneous glasses, phase separated glasses, devitrified glasses, glass ceramics, and/or multiphase glass ceramic waste forms hereafter collectively referred to as “glass waste forms” by measuring the concentrations of the chemical species released to a test solution. 1.1.1 Test Method A is a seven-day chemical durability test performed at 90 ± 2°C in a leachant of ASTM-Type I water. The test method is static and conducted in stainless steel vessels. Test Method A can specifically be used to evaluate whether the chemical durability and elemental release characteristics of nuclear, hazardous, and mixed glass waste forms have been consistently controlled during production. This test method is applicable to radioactive and simulated glass waste forms as defined above. 1.1.2 Test Method B is a durability test that allows testing at various test durations, test temperatures, mesh size, mass of sample, leachant volume, a...

American Society for Testing and Materials. Philadelphia

2002-01-01

73

MASBAL: A computer program for predicting the composition of nuclear waste glass produced by a slurry-fed ceramic melter  

Microsoft Academic Search

This report is a user's manual for the MASBAL computer program. MASBAL's objectives are to predict the composition of nuclear waste glass produced by a slurry-fed ceramic melter based on a knowledge of process conditions; to generate simulated data that can be used to estimate the uncertainty in the predicted glass composition as a function of process uncertainties; and to

Reimus

1987-01-01

74

THERMOCHEMICAL MODELS FOR NUCLEAR WASTE GLASS SUBSYSTEMS - MGO-CAO AND MGO-AL2O3  

EPA Science Inventory

A relatively simple model, the associate species model, is being applied to nuclear waste glass compositions in order to accurately predict behavior and thermodynamic activities in the material. In the model, the glass is treated as a supercooled liquid, with the liquid species ...

75

Rhenium Solubility in Borosilicate Nuclear Waste Glass: Implications for the Processing and Immobilization of Technetium-99  

SciTech Connect

The immobilization of 99Tc in a suitable host matrix has proved to be an arduous task for the researchers in nuclear waste community around the world. At the Hanford site in Washington State, the total amount of 99Tc in low-activity waste (LAW) is ~1300 kg and the current strategy is to immobilize the 99Tc in borosilicate glass with vitrification. In this context, the present article reports on the solubility/retention of rhenium, a nonradioactive surrogate for 99Tc, in a LAW borosilicate glass. Due to the radioactive nature of technetium, rhenium was chosen as a simulant because of the similarity between their ionic radii and other chemical aspects. The glasses containing Re (0 – 10,000 ppm by mass) were synthesized in vacuum-sealed quartz ampoules in order to minimize the loss of Re by volatilization during melting at 1000 °C. The rhenium was found to predominantly exist as Re (VII) in all the glasses as observed by X-ray absorption near-edge structure (XANES). The solubility of Re in borosilicate glasses was determined to be ~3000 ppm (by mass) with inductively coupled plasma-optical emission spectroscopy (ICP-OES). At higher rhenium concentrations, some additional material was retained in the glasses in the form of crystalline inclusions that were detected by X-ray diffraction (XRD) and laser ablation-ICP mass spectrometry (LA-ICP-MS). The implications of these results on the immobilization of 99Tc from radioactive wastes in borosilicate glasses have been discussed.

McCloy, John S.; Riley, Brian J.; Goel, Ashutosh; Liezers, Martin; Schweiger, Michael J.; Rodriguez, Carmen P.; Hrma, Pavel R.; Kim, Dong-Sang; Lukens, Wayne W.; Kruger, Albert A.

2012-10-26

76

Properties of nuclear waste melts and glasses: Contact-refractory corrosion and vapor phase hydration  

NASA Astrophysics Data System (ADS)

Control of refractory corrosion in waste glass melts and meeting vapor phase hydration test (VHT) requirement for Hanford low-activity waste (LAW) glass product are two critical issues among many technical challenges of nuclear waste vitrification. In this study, refractory corrosion was treated as a complex non-equilibrium, multi-component and multi-phase reactive transport process and studied both thermodynamically and kinetically. Dissolution tests of granular refractory materials into under-saturated melts coupled with crystallization tests from supersaturated melts were used to determine the possible equilibrium points. The test results show that spinet phase is the most stable phase of K-3 refractory. Solubility of glass-refractory interface material controls the long term refractory corrosion rate and protects refractory from further corrosion. Therefore, refractory corrosion rate can be possibly adjusted by controlling the underlying solubility of the interface material. A set of monolithic refractory corrosion and dissolution tests was carried out to study the kinetic effects of refractory porosity and glass melt viscosity, the two major kinetic factors associated with reactive transport process. The test results show that temperature and glass melt viscosity have intensive effects on refractory material dissolution rate. Fast closure of channels near the glass-refractory interface during corrosion reaction by fast transformation of solid solution to spinel and spinel re-crystallization helps stop further corrosion reaction. Glass composition can be "passivated" by engineering the formulation to maximizing the beneficial alteration process. For the study of VHT kinetics, data from simulated LAW glasses studied previously at Pacific Northwest National Laboratory and Vitreous State Laboratory was modeled based on Avrami equation and its variant, the so-called generalized Avrami equation for better modeling of the VHT data. The results show that the kinetics of the complex vapor hydration process is described satisfactorily by the generalized Avrami equation. The generalized Avrami equation allows the characterization of vapor phase hydration data obtained at different times and temperatures quantitatively on a common basis. The three parameters associated with the generalized Avrami equation depend strongly on glass composition. It seems that both compositional mismatch and incompatibility of a host glass to the transformed hydrous crystalline phases slow down the vapor hydration rate.

Lu, Xiaodong

77

Influence of deuteration in the glassing matrix on 13C dynamic nuclear polarization†  

PubMed Central

Replacement of protons by deuterons in the glassing solvents led to 2–3-fold improvement of the 13C dynamic nuclear polarization (DNP) solid-state NMR signal for samples doped with large electron spin resonance (ESR) linewidth free radicals galvinoxyl, DPPH, and 4-oxo-TEMPO. Meanwhile, the reverse effect is observed for 13C DNP using small ESR linewidth free radicals BDPA and trityl OX063. PMID:23552448

Lumata, Lloyd; Merritt, Matthew E.

2013-01-01

78

Nepheline Crystallization in Nuclear Waste Glasses: Progress toward acceptance of high-alumina formulations  

SciTech Connect

We have critically compiled and analyzed historical data for investigating the quantity of nepheline (NaAlSiO4) precipitation as a function of composition in simulated nuclear waste glasses. To understand composition we used two primary methods: 1) investigating the Al2O3-SiO2-Na2O ternary with filtering for different B2O3 levels and 2) creating a quadrant system consisting of compositions reduced to two metric numbers. These metrics are 1) the nepheline discriminator (ND) which depends only on the SiO2 content by weight normalized to the total weight of the Al2O3-SiO2-Na2O sub-mixture and 2) the optical basicity (OB) which contains contributions from all constituents in the glass. Nepheline precipitation is expected to be suppressed at high SiO2 levels (ND >0.62) or at low basicities (OB <0.55 to 0.57). Changes in sodium aluminosilicate glass OB due to additions of CaO and B2O3 correlate with observed effects on nepheline formation. We propose that additional composition space is available for formulating high-waste-loading, high-Al¬2O3 nuclear waste glasses when Na2O levels are less than ~0.125 (normalized by weight on the Al2O3-SiO2-Na2O sub-mixture). However, this compositional space is considerably extended to higher Na2O levels when adding >5 wt% B2O3. The OB concept can help further refine regions of nepheline-free glass formation.

McCloy, John S.; Schweiger, Michael J.; Rodriguez, Carmen P.; Vienna, John D.

2011-09-01

79

Fibrous-glass aerosols: a literature review. Special report. [On nuclear submarines  

SciTech Connect

The submarine atmospheric is a topic of interest, considering that once submerged, the craft relies on its own electrostatic precipitators (ESP's), scrubbers, and filters to create, ideally, an environment with minimal aerosolized toxic materials and other by-products. Historically, atmosphere sampling aboard nuclear submarines has shown contaminants. Other contaminants include: ozone, (major source: by-product of the ESP's); freon, (major source: ship's refrigeration system and air-conditioning plants); hydrogen, (major source: ship's batteries); carbon dioxide, (major source: human respiration); and carbon monoxide, (major source: cigarette smoking). Contaminants tested for but not found were elemental mercury and asbestos. Considering that asbestos is no longer recommended for use, secondary to its carcinogenic and co-carcinogenic qualities, fibrous glass has become a common substitute. One use of fibrous glass aboard the Ohio class submarine is acoustic and thermal insulation around perforated ducting, which runs through many exposed, high traffic spaces, i.e. crew's berthing spaces. Although the raw fibrous glass is protected from the environment it is possible, through natural wear and tear of the housing material, that at some time the insulating material may become exposed and mechanically aerosolized. Obvious questions then are: a) do submarine aerosols contain fiber glass, and b) are there health hazards related to the inhalation of these fibers. This paper reviews the current knowledge as to the health hazard of exposure.

Laverty, B.R.

1987-10-02

80

Obsidians and tektites: Natural analogues for water diffusion in nuclear waste glasses  

SciTech Connect

Projected scenarios for the proposed Yucca Mountain repository include significant periods of time when high relative humidity atmospheres will be present, thus the reaction processes of interest will include those known to occur under these conditions. The ideal natural analog for the proposed Yucca Mountain repository would consist of natural borosilicate glasses exposed to expected repository conditions for thousands of years; however, the prospects for identifying such an analog are remote, but an important caveat for using natural analog studies is to relate the reaction processes in the analog to those in the system of interest, rather than a strict comparison of the glass compositions. In lieu of this, identifying natural glasses that have reacted via reaction processes expected in the repository is the most attractive option. The goal of this study is to quantify molecular water diffusion in the natural analogs obsidian and tektites. Results from this study can be used in assessing the importance of factors affecting molecular water diffusion in nuclear waste glasses, relative to other identified reaction processes. In this way, a better understanding of the long-term reaction mechanism can be developed and incorporated into performance assessment models. 17 refs., 4 figs.

Mazer, J.J.; Bates, J.K.; Bradley, C.R. [Argonne National Lab., IL (United States); Stevenson, C.M. [Archaeological Services Consultants, Inc., Columbus, OH (United States)

1991-11-01

81

Toward Understanding the Effect of Nuclear Waste Glass Composition of Sulfur Solubility  

SciTech Connect

The concentration of sulfur in nuclear waste glass melter feed must be maintained below the point where salt accumulates on the melt surface. The allowable concentrations may range from 0.37 to over 2.05 weight percent (of SO3 on a calcined oxide basis) depending on the composition of the melter feed and processing conditions. If the amount of sulfur exceeds the melt tolerance level, a molten salt will accumulate, which may upset melter operations and potentially shorten the useful life of the melter. At the Hanford site, relatively conservative limits have been placed on sulfur loading in melter feed, which in turn significantly increases the amount of glass that will be produced. Crucible-scale sulfur solubility data and scaled melter sulfur tolerance data have been collected on simulated Hanford waste glasses over the last 15 years. These data were compiled and analyzed. A model was developed to predict the solubility of SO3 in glass based on 252 simulated Hanford low-activity waste (LAW) glass compositions. This model represents the data well, accounting for over 85% of the variation in data, and was well validated. The model was also found to accurately predict the tolerance for sulfur in melter feed for 13 scaled melter tests of simulated LAW glasses. The model can be used to help estimate glass volumes and make informed decisions on process options. The model also gives quantitative estimates of component concentration effects on sulfur solubility. The components that most increase sulfur solubility are Li2O > V2O5> CaO ? P2O5 > Na2O ? B2O3 > K2O. The components that most decrease sulfur solubility are Cl > Cr2O3 > Al2O3 > ZrO2 ? SnO2 > Others ? SiO2. The order of component effects is similar to previous literature data, in most cases.

Vienna, John D.; Kim, Dong-Sang; Muller, I. S.; Kruger, Albert A.; Piepel, Gregory F.

2014-02-13

82

A two-dimensional deuterium nuclear magnetic resonance study of molecular reorientation in sugar\\/water glasses  

Microsoft Academic Search

Two-dimensional nuclear magnetic resonance time domain analysis of the stimulated echo experiment is used to study the molecular reorientation of deuterated glucose molecules in a glucose\\/water glass at about 15 °C above the glass transition. By measuring both the cos-cos and sin-sin two-time single particle correlation functions it is shown that the reorientation is isotropic, which enables the determination of

Andrew M. Wachner; Kenneth R. Jeffrey

1999-01-01

83

GdBr3: CE in a glass wafer as a nuclear radiation monitor.  

PubMed

A glass wafer that contains cerium-activated gadolinium-based scintillator has been tested as a nuclear radiation monitor. The detector is prepared by mixing powdered gadolinium and cerium (3+) bromides with alumina, silica, and lithium fluoride, melting the mixture at 1,400°C, and then quenching and annealing the glass. The resulting clear glass matrix emits stimulated blue light that can be collected by a conventional photomultiplier tube. Spectral analysis of radionuclides with this detector shows the energy peaks for alpha particles, the energy continuum for beta particles, the Compton continuum and full-energy peaks for gamma rays, and an energy continuum with specific reaction-product peaks for neutrons. Energy resolution for the 5.5-MeV alpha particle and 0.662-MeV gamma-ray peaks is about 20%. This resolution, although threefold poorer than for single-crystal NaI(Tl) scintillators, contributes to radionuclide identification and quantification. Application of this detector to radiation monitoring is proposed, as well as approaches for improving light collection and energy resolution that will facilitate radionuclide identification and monitoring, especially for alpha particles, beta particles, and low-energy gamma rays. PMID:23532079

Kang, Zhitao; Rosson, Robert; Barta, M Brooke; Nadler, Jason; Wagner, Brent; Kahn, Bernd

2013-05-01

84

Model for the conversion of nuclear waste melter feed to glass  

NASA Astrophysics Data System (ADS)

The rate of batch-to-glass conversion is a primary concern for the vitrification of nuclear waste, as it directly influences the life cycle of the cleanup process. This study describes the development of an advanced model of the cold cap, which augments the previous model by further developments on the structure and the dynamics of the foam layer. The foam layer on the bottom of the cold cap consists of the primary foam, cavities, and the secondary foam, and forms an interface through which the heat is transferred to the cold cap. Other model enhancements include the behavior of intermediate crystalline phases and the dissolution of quartz particles. The model relates the melting rate to feed properties and melter conditions, such as the molten glass temperature, foaminess of the melt, or the heat fraction supplied to the cold cap from the plenum space. The model correctly predicts a 25% increase in melting rate when changing the alumina source in the melter feed from Al(OH)3 to AlO(OH). It is expected that this model will be incorporated in the full glass melter model as its integral component.

Pokorny, Richard; Hrma, Pavel

2014-02-01

85

Characterization of borate glasses by W-band pulse electron-nuclear double resonance spectroscopy  

NASA Astrophysics Data System (ADS)

(100-x)mol% B2O3 x mol % Me2O (Me=Li,Na,K) glasses, exposed to ?-Co60 irradiation to produce paramagnetic states, were characterized by W-band (95GHz ) pulse electron-nuclear double resonance (ENDOR) spectroscopy in order to characterize local structures occurring in the range of compositions between x =16 and x =25 at which the "boron oxide" anomaly occurs. The high resolution of nuclear frequencies allowed resolving the Li7 and B11 ENDOR lines. In the samples with x =16 and x =20 glasses, B11 hyperfine couplings of 16, 24, and 36MHz were observed and attributed to the tetraborate, triborate, and boron oxygen hole center (BOHC) structures, respectively. The x =25 samples showed hyperfine couplings of 15MHz for the tetraborate and 36MHz for BOHC. Density functional theory (DFT) calculations predicted for these structures negative hyperfine couplings, which were confirmed by W-band ENDOR. This suggests that a spin polarization mechanism accounts for the negative hyperfine structure splitting.

Kordas, George; Goldfarb, Daniella

2008-10-01

86

Characterization of borate glasses by W-band pulse electron-nuclear double resonance spectroscopy  

SciTech Connect

(100-x) mol % B{sub 2}O{sub 3} x mol %Me{sub 2}O (Me=Li,Na,K) glasses, exposed to {gamma}-{sup 60}Co irradiation to produce paramagnetic states, were characterized by W-band (95 GHz) pulse electron-nuclear double resonance (ENDOR) spectroscopy in order to characterize local structures occurring in the range of compositions between x=16 and x=25 at which the 'boron oxide' anomaly occurs. The high resolution of nuclear frequencies allowed resolving the {sup 7}Li and {sup 11}B ENDOR lines. In the samples with x=16 and x=20 glasses, {sup 11}B hyperfine couplings of 16, 24, and 36 MHz were observed and attributed to the tetraborate, triborate, and boron oxygen hole center (BOHC) structures, respectively. The x=25 samples showed hyperfine couplings of 15 MHz for the tetraborate and 36 MHz for BOHC. Density functional theory (DFT) calculations predicted for these structures negative hyperfine couplings, which were confirmed by W-band ENDOR. This suggests that a spin polarization mechanism accounts for the negative hyperfine structure splitting.

Kordas, George [Sol Gel Laboratory for Glass and Ceramics, Institute of Materials Science, NCSR 'Demokritos', 15310 Aghia Paraskevi Attikis (Greece); Goldfarb, Daniella [Department of Chemical Engineering, Weizmann Institute of Science, 76100 Rehovot (Israel)

2008-10-21

87

Radiation effects in moist-air systems and the influence of radiolytic product formation on nuclear waste glass corrosion  

SciTech Connect

Ionizing radiation may affect the performance of glass in an unsaturated repository site by interacting with air, water vapor, or liquid water to produce a variety of radiolytic products. Tests were conducted to examine the effects of radiolysis under high gas/liquid ratios. Results indicate that nitrate is the predominant radiolytic product produced following both gamma and alpha radiation exposure, with lesser amounts of nitrite and carboxylic acids. The formation of nitrogen acids during exposure to long-lived, alpha-particle-emitting transuranic elements indicates that these acids may play a role in influencing nuclear waste form reactions in a long-term unsaturated disposal scenario. Experiments were also conducted with samples that simulate the composition of Savannah River Plant nuclear waste glasses. Radiolytic product formation in batch tests (340 m{sup {minus}1}, 90 C) resulted in a small increase in the release rates of many glass components, such as alkali and alkaline earth elements, although silicon and uranium release rates were slightly reduced indicating an overall beneficial effect of radiation on waste form stability. The radiolytic acids increased the rate of ion exchange between the glass and the thin film of condensate, resulting in accelerated corrosion rates for the glass. The paragenetic sequence of alteration phases formed on both the irradiated and nonirradiated glass samples reacted in the vapor hydration tests matches closely with those developed during volcanic glass alteration in naturally occurring saline-alkaline lake systems. This correspondence suggests that the high temperatures used in these tests have not changed the underlying glass reaction mechanism relate to that which controls glass reactions under ambient surficial conditions.

Wronkiewicz, D.J.; Bates, J.K.; Buck, E.C.; Hoh, J.C.; Emery, J.W. [Argonne National Lab., IL (United States). Chemical Technology Div.; Wang, L.M. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Geology

1997-07-01

88

Heat Transfer in Waste Glass Melts - Measurement and Implications for Nuclear Waste Vitrification  

NASA Astrophysics Data System (ADS)

Thermal properties of waste glass melts, such as high temperature density and thermal conductivity, are relevant to heat transfer processes in nuclear waste vitrification. Experimental measurement techniques were developed and applied to four nuclear waste glasses representative of those currently projected for treatment of Hanford HLW and LAW streams to study heat flow mechanisms in nuclear waste vitrification. Density measurement results by Archimedes' method indicated that densities of the melts investigated varied considerably with composition and temperature. Thermal diffusivities of waste melts were determined at nominal melter operating temperatures using a temperature-wave technique. Thermal conductivities were obtained by combining diffusivity data with the experimentally-acquired densities of the melts and their known heat capacities. The experimental results display quite large positive dependences of conductivities on temperature for some samples and much weaker positive temperature dependences for others. More importantly, there is observed a big change in the slopes of the conductivities versus temperature as temperature is increased for two of the melts, but not for the other two. This behavior was interpreted in terms of the changing contributions of radiation and conduction with temperature and composition dependence of the absorption coefficient. Based on the obtained thermal conductivities, a simple model for a waste glass melter was set up, which was used to analyze the relative contributions of conduction and radiation individually and collectively to the overall heat flow and to investigate factors and conditions that influence the radiation contribution to heat flow. The modeling results showed that unlike the case at lower temperatures, the radiant energy flow through waste melts could be predominant compared with conduction at temperature of about 900 °C or higher. However, heat flow due to radiation was roughly equal to that from conduction as temperatures below about 700 °C. Moreover, the effect was reduced for higher absorption coefficient samples. Modeling further demonstrated that geometry exerts a significant influence on the radiation contribution to heat transfer. Room temperature radiation absorption coefficients of the same samples were determined using FTIR, which were compared with those estimated by modeling.

Wang, Chuan

89

Relaxation transition in glass-forming polybutadiene as revealed by nuclear resonance X-ray scattering.  

PubMed

We investigated the arrest mechanism of molecular motions in a glass forming polybutadiene near the glass transition using a new nuclear resonance synchrotron X-ray scattering technique to cover a wide time range (10(-9) to 10(-5) s) and a scattering vector Q range (9.6-40 nm(-1)), which have never been accessed by other methods. Owing to the wide time and Q ranges it was found for the first time that a transition of the ?-process to the slow ?-process (or the Johari-Goldstein process) was observed in a Q range higher than the first peak in the structure factor S(Q) at the critical temperature T(c) in the mode coupling theory. The results suggest the important roles of hopping motions below T(c), which was predicted by the recent extended mode coupling theory and the cooperative motions due to the strong correlation at the first peak in S(Q) in the arrest mechanism. PMID:24735317

Kanaya, Toshiji; Inoue, Rintaro; Saito, Makina; Seto, Makoto; Yoda, Yoshitaka

2014-04-14

90

An evaluation of glass-crystal composites for the disposal of nuclear and hazardous waste materials  

SciTech Connect

Waste forms made of a glass-crystal composite (GCC) are being evaluated at Argonne National Laboratory for their potential use in the disposal of low-level nuclear and hazardous waste materials. This waste form is being developed within the framework strategy of DOE`s minimum Additive Waste Stabilization (MAWS) Program. The MAWS protocol involves the blending of multiple waste streams to achieve an optimal feed composition, which eliminates the need to use large amounts of additives to produce an acceptable waste form. The GCCs have a particularly useful utility in their ability to incorporate waste streams with high metal contents, including those that contain large amounts of scrap metals, and in their potential for sequestering radionuclide and hazardous constituents in corrosion-resistant mineral phases. This paper reports the results from tests conducted with simulated feeds representative of potential DOE and industry waste streams. Topics addressed include the partitioning of various radioactive and hazardous constituents between the glass and crystalline portions of the waste form, the development of secondary phases on the altered sample surfaces during corrosion testing, and the fate of waste components during corrosion testing, as indicated by elements released to solution and microanalysis of the reacted solid samples.

Wronkiewicz, D.J.; DiSanto, T.; Wolf, S.F.; Buck, E.C.; Dietz, N.L. [Argonne National Lab., IL (United States); Feng, X. [Pacific Northwest Lab., Richland, WA (United States)

1995-03-01

91

Dynamics of asymmetric binary glass formers. II. Results from nuclear magnetic resonance spectroscopy  

SciTech Connect

Various {sup 2}H and {sup 31}P nuclear magnetic resonance (NMR) spectroscopy techniques are applied to probe the component dynamics of the binary glass former tripropyl phosphate (TPP)/polystyrene-d{sub 3} (PS) over the full concentration range. The results are quantitatively compared to those of a dielectric spectroscopy (DS) study on the same system previously published [R. Kahlau, D. Bock, B. Schmidtke, and E. A. Rössler, J. Chem. Phys. 140, 044509 (2014)]. While the PS dynamics does not significantly change in the mixtures compared to that of neat PS, two fractions of TPP molecules are identified, one joining the glass transition of PS in the mixture (?{sub 1}-process), the second reorienting isotropically (?{sub 2}-process) even in the rigid matrix of PS, although at low concentration resembling a secondary process regarding its manifestation in the DS spectra. Pronounced dynamical heterogeneities are found for the TPP ?{sub 2}-process, showing up in extremely stretched, quasi-logarithmic stimulated echo decays. While the time window of NMR is insufficient for recording the full correlation functions, DS results, covering a larger dynamical range, provide a satisfactory interpolation of the NMR data. Two-dimensional {sup 31}P NMR spectra prove exchange within the broadly distributed ?{sub 2}-process. As demonstrated by {sup 2}H NMR, the PS matrix reflects the faster ?{sub 2}-process of TPP by performing a spatially highly hindered motion on the same timescale.

Bock, D.; Kahlau, R.; Pötzschner, B.; Körber, T.; Wagner, E.; Rössler, E. A., E-mail: ernst.roessler@uni-bayreuth.de [Experimentalphysik II, Universität Bayreuth, 95440 Bayreuth (Germany)

2014-03-07

92

Comprehensive data base of high-level nuclear waste glasses: September 1987 status report: Volume 2, Additional appendices  

SciTech Connect

The Materials Characterization Center (MCC) is assembling a comprehensive data base (CDB) of experimental data collected for high-level nuclear waste package components. The status of the CDB is summarized in Volume I of this report. Volume II contains appendices that present data from the data base and an evaluation of glass durability models applied to the data base.

Kindle, C.H.; Kreiter, M.R.

1987-12-01

93

The determination of the Fe sup 2+ /Fe sup 3+ ratio in simulated nuclear waste glass by ion chromatography  

SciTech Connect

Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass in the Defense Waste Processing Facility (DWPF). In this facility, control of the oxidation/reduction (redox) equilibrium in the glass melter is critical for processing of the nuclear waste. Therefore, the development of a rapid and reliable analytical method for the determination of the redox equilibrium is of considerable interest. Redox has been determined by measuring the ratio of ferrous to ferric ions in the glass melt. Two analytical techniques for glass redox measurement have been investigated for the DWPF: Mossbauer Spectroscopy which may be subject to interferences from the radiation in actual waste, and a rapid and simple chemical dissolution/spectrophotometric technique. Comparisons of these techniques have been made at several laboratories including Clemson University. In the study attached, the determination of the redox ratio by Ion Chromatography (IC) was investigated as a potential new technology. Clemson University performed IC analyses on the same glasses as previously examined by wet chemical and Mossbauer techniques. Results from all three techniques were highly correlated and IC was reported to be a promising new technology for redox measurement. 19 refs., 19 figs., 5 tabs.

Jantzen, C.M.

1990-10-01

94

Measurement of the nuclear electromagnetic cascade development in glass at energies above 200 GeV  

NASA Technical Reports Server (NTRS)

The longitudinal development of nuclear-electromagnetic cascades with energies greater than 200 GeV was measured in a low-Z (glass) absorber. This was done in the course of operating an ionization spectrometer at mountain altitude in an experiment to study the properties of gamma rays emitted from individual interactions at energies around 10,000 GeV. The ionization produced by a cascade is sampled by 20 sheets of plastic scintillator spaced uniformly in depth every 2.2 radiation lengths. Adjacent pairs of scintillators are viewed by photomultipliers which measure the mean ionization produced by an individual cascade in 10 layers each 1.1 interaction length (4.4 radiation lengths) thick. The longitudinal development of the cascades was measured for about 250 cascades having energies ranging from 200 GeV to 2500 GeV. The observations are compared with the predictions of calculations made for this specific spectrometer using a three-dimensional Monte Carlo model of the nuclear-electromagnetic cascade.

Gillespie, C. R.; Huggett, R. W.; Humphreys, D. R.; Jones, W. V.; Levit, L. B.

1971-01-01

95

The relationship between glass viscosity and composition: A first principles model for vitrification of nuclear waste  

SciTech Connect

The Defense Waste Processing Facility will incorporate high-level liquid waste into borosilicate glass for stabilization and permanent disposal in a geologic repository. The viscosity of the melt determines the rate of melting of the raw feed, the rate of gas bubble release due to foaming and fining, the rate of homogenization, and thus, the quality of the glass produced. The viscosity of the glass is in turn, a function of both glass composition and temperature. A model describing the viscosity dependence on composition, temperature, and glass structure (bonding) has been derived for glasses ranging from pure frits to frit plus 35 wt % simulated waste. 17 refs., 37 figs.

Jantzen, C.M.

1990-12-31

96

Cerium, uranium, and plutonium behavior in glass-bonded sodalite, a ceramic nuclear waste form.  

SciTech Connect

Glass-bonded sodalite is being developed as a ceramic waste form (CWF) to immobilize radioactive fission products, actinides, and salt residues from electrometallurgical treatment of spent nuclear reactor fuel. The CWF consists of about 75 mass % sodalite, 25 mass % glass, and small amounts of other phases. This paper presents some results and interpretation of physical measurements to characterize the CWF structure, and dissolution tests to measure the release of matrix components and radionuclides from the waste form. Tests have been carried out with specimens of the CWF that contain rare earths at concentrations similar to those expected in the waste form. Parallel tests have been carried out on specimens that have uranium or plutonium as well as the rare earths at concentrations similar to those expected in the waste forms; in these specimens UCl{sub 3} forms UO{sub 2} and PuCl{sub 3} forms PuO{sub 2}. The normalized releases of rare earths in dissolution tests were found to be much lower than those of matrix elements (B, Si, Al, Na). When there is no uranium in the CWF, the release of cerium is two to ten times lower than the release of the other rare earths. The low release of cerium may be due to its tetravalent state in uranium-free CWF. However, when there is uranium in the CWF, the release of cerium is similar to that of the other rare earths. This trivalent behavior of cerium is attributed to charge transfer or covalent interactions among cerium, uranium, and oxygen in (U,Ce)O{sub 2}.

Lewis, M. A.; Lexa, D.; Morss, L. R.; Richmann, M. K.

1999-09-03

97

Transmission electron microscopy of simulated DWPF high level nuclear waste glasses following gamma irradiation  

Microsoft Academic Search

In the near future the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) will begin stabilizing high-level radioactive waste using borosilicate glass. The molten waste glass will be poured into stainless steel canisters which, after cooling, will be sealed shut to produce the canistered waste forms. Following interim storage at SRS, the glass-filled canisters will be shipped

J. C. Marra; N. E. Bibler; J. R. Harbour; M. H. Tosten

1994-01-01

98

A review on immobilization of phosphate containing high level nuclear wastes within glass matrix--present status and future challenges.  

PubMed

Immobilization of phosphate containing high level nuclear wastes within commonly used silicate glasses is difficult due to restricted solubility of P(2)O(5) within such melts and its tendency to promote crystallization. The situation becomes more adverse when sulfate, chromate, etc. are also present within the waste. To solve this problem waste developers have carried out significant laboratory scale research works in various phosphate based glass systems and successfully identified few formulations which apparently look very promising as they are chemically durable, thermally stable and can be processed at moderate temperatures. However, in the absence of required plant scale manufacturing experiences it is not possible to replace existing silicate based vitrification processes by the phosphate based ones. A review on phosphate glass based wasteforms is presented here. PMID:22902141

Sengupta, Pranesh

2012-10-15

99

Reaction and devitrification of a prototype nuclear-waste-storage glass with hot magnesium-rich brine  

SciTech Connect

PNL 76-68, a prototype nuclear waste storage glass, was reacted under hydrothermal conditions at 100, 200, and 300 C with NBT-6a (Ca-Mg-K-Na-Cl) brine. Reaction products were identified, the state of the residual glass determined, and the concentrations of various elements remaining in the solutions analyzed. Solid products formed by reaction of the glass and brine talc (hydrated magnesium silicate), powellite (CaMoO/sub 4/), hematite (Fe/sub 2/O/sub 3/) and rarely an unidentified uranium-containing phase. Glass fragments were leached to depths of 300 to 500 ..mu..m, depending on time and temperature. Most elements were extracted, but the silicate framework remained intact. Distinct diffusion fronts due to K/Na exchange and Mg/Zn exchange were identified. A complex compositional layering develops in the outer reaction rind. The concentration of silica in brine solution was lower by an order of magnitude than the concentration of silica in deionized water reacted under similar conditions. The concentration of cesium, strontium, uranium, rare earths, and other alkali and alkaline earth elements in solution increases exponentially with temperature of reaction. Behavior of the transition metals is more complex. In general the extraction of elements from the glass by hydrothermal brine leads to concentrations in solution that are from 10 to 100 times higher than the concentrations obtained by deionized water extraction under similar conditions of temperature and pressure.

Komarneni, S.; Freeborn, W.P.; Scheetz, B.E.; White, W.B.; McCarthy, G.J.

1982-10-01

100

IMPACT OF URANIUM AND THORIUM ON HIGH TIO2 CONCENTRATION NUCLEAR WASTE GLASSES  

SciTech Connect

This study focused on the potential impacts of the addition of Crystalline Silicotitanate (CST) and Monosodium Titanate (MST) from the Small Column Ion Exchange (SCIX) process on the Defense Waste Processing Facility (DWPF) glass waste form and the applicability of the DWPF process control models. MST from the Salt Waste Processing Facility (SWPF) is also considered in the study. The KT08-series of glasses was designed to evaluate any impacts of the inclusion of uranium and thorium in glasses containing the SCIX components. All but one of the study glasses were found to be amorphous by X-ray diffraction (XRD). One of the slowly cooled glasses contained a small amount of trevorite, which is typically found in DWPF-type glasses and had no practical impact on the durability of the glass. The measured Product Consistency Test (PCT) responses for the study glasses and the viscosities of the glasses were well predicted by the current DWPF models. No unexpected issues were encountered when uranium and thorium were added to the glasses with SCIX components.

Fox, K.; Edwards, T.

2012-01-11

101

Resarch investigation on dense scintillation glass for use in total absorption nuclear cascade detectors  

NASA Technical Reports Server (NTRS)

Three approaches to the development of a high density scintillation glass were investigated: They include the increase of density of glass systems containing cerium - the only systems which were known to show scintillation, the testing of a novel silicate glass system containing significant concentrations of silver produced by ion exchange and never tested previously, and the hot pressing of a diphasic compact of low density scintillation glass with high density passive glass. In first two cases, while ultraviolet excited fluorescence was maintained in the glasses showing high density, scintillation response to high energy particles was not retained in the case of the cerium containing glasses or developed in the case of the silver containing glasses. In the case of the compacts, the extremely long path length caused by the multiple internal reflections which occur in such a body resulted in attenuation even with glasses of high specific transmission. It is not clear why the scintillation efficiency is not maintained in the higher density cerium containing glasses.

Hensler, J. R.

1973-01-01

102

INTRINSIC DOSIMETRY OF GLASS CONTAINERS USED TO TRANSPORT NUCLEAR MATERIALS: Potential Implications to the Field of Nuclear Forensics  

SciTech Connect

Thermoluminescence (TL) and Electron Paramagnetic Resonance (EPR) dosimetry were used to measure dose effects in borosilicate glass with time, from 10 minutes to ~60 days following exposure to a dose of up to 10,000 Rad. TL and EPR results were consistent and performed similarly, with both techniques capable of achieving an estimated limit of detection of between 50-100 Rad. Three peaks were identified in the TL glow curve at roughly 110oC, 205oC, and 225oC. The intensity of the 205oC peak was the dominant peak over the time period of this study. The stability of all of the peaks with time since irradiation increased with their corresponding temperature and little or no variation was observed in the glow curve response to a specified total dose attained at different dose rates. The intensity of the 205oC peak decreased logarithmically with time regardless of total dose. Based upon a conservative limit of detection of 330 Rad, a 10,000 Rad dose would still be detected 2.7E3 years after exposure. This paper introduces the concept of intrinsic dosimetry, the consideration of a measured dose received to container walls in concert with the physical characteristics of the radioactive material contained inside those walls, as a method for gathering rather unique pathway information about the history of that sample. Three hypothetical scenarios are presented to introduce this method and to illustrate how intrinsic dosimetry might benefit the fields of nuclear forensics and waste management.

Schwantes, Jon M.; Miller, Steven D.; Piper, Roman K.; Murphy, Mark K.; Amonette, James E.; Bonde, Steven E.; Duckworth, Douglas C.

2008-09-15

103

LITHIUM-7, BORON-10, BORON-11, and OXYGEN-17 Nuclear Magnetic Resonance Studies of Lithium Borate Glasses and Related Compounds.  

NASA Astrophysics Data System (ADS)

Nuclear Magnetic Resonance (NMR) studies of lithium borate glasses employing the two stable isotopes of boron, B('10) and B('11), were used in the formulation of a consistent structural model throughout the glass-forming region. The ideas of Krogh-Moe were used in which the glasses are viewed as mixtures of units found in corresponding crystalline compounds. For low-alkali oxide content glasses the results are in good agreement with those obtained by Jellison and Bray in sodium borate glasses. These glasses are viewed as being mixtures of boroxol, tetraborate and diborate units. Intermediate-alkali oxide content glasses satisfy a model proposed in this thesis in which diborate and tetraborate units are destroyed to form loose N('4) and metaborate units. For high-alkali oxide content glasses the results are in good agreement with a model proposed by Yun and Yun and Bray in which loose N('4), metaborate, pyroborate and orthoborate units exist. Li(,2)O, enriched in O('17), was synthesized in such a way that H(,2)O enriched to 54% O('17) was efficiently transferred into Li(,2)O. It is hypothesized that the synthesis of Li(,2)O enriched in O('17) as well as the synthesis of the other alkali oxides (e.g. Na(,2)O, K(,2)O, Rb(,2)O and Cs(,2)O) will greatly enlarge the range of O('17) NMR studies of glasses and related compounds. Li('7) and O('17) NMR studies of Li(,2)O revealed structureless derivative spectra of linewidths 9.9 gauss and 5.8 gauss, respectively. These experimental results were compared to a second-moment calculation of the linewidths using the anti-fluorite crystal structure for Li(,2)O. O('17) NMR studies of two lithium borate compounds, lithium metaborate (Li(,2)O(.)B(,2)O(,3)) and lithium orthoborate (3Li(,2)O(.)B(,2)O(,3)) were used to identify the quadrupole parameters of bridging and non-bridging oxygen atoms. These results, in conjunction with B('11) NMR results from these compounds, were used to determine charge densities associated with the boron and oxygen atoms by means of the simplifying approximations of Townes and Dailey.

Feller, Steven Allen

1980-06-01

104

The reaction of synthetic nuclear waste glass in steam and hydrothermal solution  

SciTech Connect

Glass monoliths of the WVCM 44, WVCM 50, SRL 165, and SRL 202 compositions were reacted in steam and in hydrothermal liquid at 200{degree}C. The glass reaction resulted in the formation of leached surface layers in both environments. The reaction in steam proceeds at a very low rate until precipitates form, after which the glass reaction proceeds at a greater rate. Precipitates were formed on all glass types reacted in steam. The assemblage of phases formed was unique to each glass type, but several precipitates were common to all glasses, including analcime, gyrolite, and weeksite. Reaction in steam occurs in a thin layer of condensed water which becomes saturated with respect to the observed phases after only a few days of reaction. The reaction in steam is accelerated relative to reaction in hydrothermal liquid in the sense that secondary phases from after a shorter reaction time, that is, after less glass has reacted, because of the smaller effective leachant volume present in the steam environment. A knowledge of the secondary phases which form and their influence on the glass reaction rate is crucial to the modeling effort of the repository program. 9 refs., 3 figs., 2 tabs.

Ebert, W.L.; Bates, J.K.

1989-12-31

105

Induction glass melting under conditioning highly- and moderately active nuclear wastes  

Microsoft Academic Search

The most reliable method of HLW stabilization is vitrification. To be solidified radioactive waste as a solution of salts of different humidities or mixed oxides are pre-mixed with glass-formers need to produce glass, fed to be concentrated and then into a melter. The paper discusses the results of the work to vitrify liquid HLW by a two stage process using

Y. B. Petrov; D. B. Lopukh; A. M. Lyubomirov

1993-01-01

106

First principles process-product models for vitrification of nuclear waste: Relationship of glass composition to glass viscosity, resistivity, liquidus temperature, and durability  

SciTech Connect

Borosilicate glasses will be used in the USA and in Europe to immobilize radioactive high level liquid wastes (HLLW) for ultimate geologic disposal. Process and product quality models based on glass composition simplify the fabrication of the borosilicate glass while ensuring glass processability and quality. The process model for glass viscosity is based on a relationship between the glass composition and its structural polymerization. The relationship between glass viscosity and electrical resistivity is also shown to relate to glass polymerization. The process model for glass liquidus temperature calculates the solubility of the liquidus phases based on the free energies of formation of the precipitating species. The durability product quality model is based on the calculation of the thermodynamic hydration free energy from the glass composition.

Jantzen, C.M.

1991-12-31

107

First principles process-product models for vitrification of nuclear waste: Relationship of glass composition to glass viscosity, resistivity, liquidus temperature, and durability  

SciTech Connect

Borosilicate glasses will be used in the USA and in Europe to immobilize radioactive high level liquid wastes (HLLW) for ultimate geologic disposal. Process and product quality models based on glass composition simplify the fabrication of the borosilicate glass while ensuring glass processability and quality. The process model for glass viscosity is based on a relationship between the glass composition and its structural polymerization. The relationship between glass viscosity and electrical resistivity is also shown to relate to glass polymerization. The process model for glass liquidus temperature calculates the solubility of the liquidus phases based on the free energies of formation of the precipitating species. The durability product quality model is based on the calculation of the thermodynamic hydration free energy from the glass composition.

Jantzen, C.M.

1991-01-01

108

A review of literature pertaining to the leaching and sorption of radionuclides associated with nuclear explosive melt glasses  

SciTech Connect

For the purposes of groundwater characterization, environmental remediation and health risk assessment, the mechanism and rate by which radionuclides bound within nuclear device melt glass are manifest in Nevada Test Site groundwaters must be known. Exchange between radionuclides and groundwater is dominated by the kinetics of leaching and the resultant sorption of derivative nuclides by minerals along the flow-path. In this context, a survey of the report literature has been conducted to review work related to these subjects. This report provides a representative, although not exhaustive, summary of the literature; because of the specialized nature of nuclear melt glass, emphasis was given to the report literature available from Lawrence Livermore and Los Alamos National Laboratories, the Department of Energy and its predecessor agencies and pertinent contractors. Where data is corroborated in journal literature, those references are also included. Before the risk to ground waters is estimated with any accuracy, recommendations for continued future work integrate systematic characterization of melt glass with leaching studies of these heterogeneous matrices.

Smith, D.K.

1993-05-01

109

Leaching Savannah River Plant nuclear waste glass in a saturated tuff environment  

SciTech Connect

Samples of SRP glass containing either simulated or actual radioactive waste were leached at 90{sup 0}C under conditions simulating a saturated tuff repository environment. The leach vessels were fabricated of tuff and actual tuff groundwater was used. Thus, the glass was leached only in the presence of those materials (including the Type 304L stainless steel canister material) that would be in the actual repository. Tests were performed for time periods up t 6 months at a SA/V ratio of 100 m{sup -1}. Results with glass containing simulated waste indicated that stainless steel canister material around the glass did not significantly affect the leaching. Based on Li and B (elements not in significant concentrations in the tuff or tuff groundwater), glass containing simulated waste leached identically to glass containing actual radioactive waste. The tuff buffered the pH so that only a slight increase was observed as a result of leaching. Results with glass containing actual radioactive waste indicated that tuff reduced the concentrations of Cs-137, Sr-90, and Pu-238 in the free groundwater in the simulated repository by 10 to 100X. Also, radiolysis of the groundwater by the glass (approximately 1000 rad/h) did not significantly affect the pH in the presence of tuff. Measured normalized mass losses in the presence of tuff for the glass based on Cs-137, Sr-90, and Pu-238 in the free groundwater were extremely low, nominally 0.02, 0.02, and 0.005 g/m{sup 2}, respectively, indicating that the glass-tuff system retained radionuclides well. 9 references, 2 figures, 3 tables.

Bibler, N.E.; Wicks, G.G.; Oversby, V.M.

1984-11-01

110

The liquidus temperature of nuclear waste glasses: an international Round-Robin Study  

SciTech Connect

Ten institutions from five countries participated in a Round Robin study to contribute to the Precision and Bias section of an American Society for Testing and Materials standard procedure that Pacific Northwest National Laboratory (PNNL) is developing for measuring the liquidus temperature (TL) of radioactive and simulated waste glasses. In this study, three separate TL measurement methods were a gradient temperature (GT) method, a uniform temperature (UT) method, and a crystal fraction extrapolation (CF) method. Three different glasses were measured with a combination of these three methods. The TL values reported by different institutions are generally consistent and vary within a narrow range. The precision of a TL measurement was evaluated as ±10°C regardless of the method used for making the measurement. The Round Robin glasses were all previously studied at PNNL and included ARG-1 (Glass A), Zr-9 (Glass B), and AmCm2-19 (Glass C), with measured TL values spanning the temperature range ~960-1240°C. The three methods discussed here in more detail are the GT, UT, and CF methods. A best-case precision for TL has been obtained from the data, even though the data were not acquired for all three glasses using all three methods from each participating organization.

Riley, Brian J.; Hrma, Pavel R.; Vienna, John D.; Schweiger, Michael J.; Rodriguez, Carmen P.; Crum, Jarrod V.; Lang, Jesse B.; Marra, James C.; Johnson, Fabienne; Peeler, David K.; Leonelli, Cristina; Ferrari, Anna M.; Lancellotti, Isabella; Dussossoy, Jean-Lue A.; Hand, Russell J.; Schofield, James M.; Connelly, Andrew J.; Short, Rick; Harrison, Mike T.

2012-12-01

111

Development of Vitrification Process and Glass Formulation for Nuclear Waste Conditioning  

SciTech Connect

The vitrification of high-level waste is the internationally recognized standard to minimize the impact to the environment resulting from waste disposal as well as to minimize the volume of conditioned waste to be disposed of. COGEMA has been vitrifying high-level waste industrially for over 20 years and is currently operating three commercial vitrification facilities based on a hot metal crucible technology, with outstanding records of safety, reliability and product quality. To further increase the performance of vitrification facilities, CEA and COGEMA have been developing the cold crucible melter technology since the beginning of the 1980s. This type of melter is characterized by a virtually unlimited equipment service life and a great flexibility in dealing with various types of waste and allowing development of high temperature matrices. In complement of and in parallel with the vitrification process, a glass formulation methodology has been developed by the CEA in order to tailor matrices for the wastes to be conditioned while providing the best adaptation to the processing technology. The development of a glass formulation is a trade-off between material properties and qualities, technical feasibility, and disposal safety criteria. It involves non-radioactive and radioactive laboratories in order to achieve a comprehensive matrix qualification. Several glasses and glass ceramics have thus been studied by the CEA to be compliant with industrial needs and waste characteristics: glasses or other matrices for a large spectrum of fission products, or for high contents of specifics elements such as sodium, phosphate, iron, molybdenum, or actinides. New glasses or glass-ceramics designed to minimize the final wasteform volume for solutions produced during the reprocessing of high burnup fuels or to treat legacy wastes are now under development and take benefit from the latest CEA hot-laboratories and technology development. The paper presents the CEA state-of-the-art in developing matrices or glasses and provides several examples.

Petitjean, V.; Fillet, C.; Boen, R.; Veyer, C.; Flament, T.

2002-02-26

112

X-ray photoelectron spectroscopy and nuclear magnetic resonance structural study of phosphorus oxynitride glasses, ‘LiNaPON’  

Microsoft Academic Search

In this study, the structure of mixed alkali nitrided phosphate glasses ‘LiNaPON’, of composition Li0.5Na0.5PO3?3x\\/2Nx(0nuclear magnetic resonance (NMR) spectroscopies. XPS results show that nitrogen N3? exists as two-coordinated –N? atoms and three-coordinated –N? atoms, respectively bonded to two and three phosphorus atoms, thus

André Le Sauze; Lionel Montagne; Gérard Palavit; Franck Fayon; Roger Marchand

2000-01-01

113

Through the looking glass: placing India's new civil liability regime for nuclear damage in context  

Microsoft Academic Search

Tntil India adopted the Civil Liability for Nuclear Damage Act, 2010 (Liability Act) and the Civil Liability for Nuclear Damage Rules, 2011 (Liability Rules or Rules),1 no specific legislation was in place to govern nuclear liability or to compensate victims for damages due to a nuclear incident in India.

Robert J. Gruendel; Els Reynaers Kini

2012-01-01

114

Thermodynamics and kinetics of crystallization of near-liquidus crystalline phases in defense nuclear waste glass melts  

NASA Astrophysics Data System (ADS)

Vitrification has been identified as the primary mode of nuclear waste immobilization. Two important factors that affect the economic success of the vitrification program are waste loading and melter life. High-level nuclear waste (HLW) streams often contain significant amounts of Fe, Ni, Mn and Cr. Some of these waste streams contain significant amounts of Zr, Th & U. This often leads to the crystallization of iron-chrome spinels or oxides/silicates of Zr, Th and U as the near-liquidus phases. The waste loading that can be achieved is often limited by crystallization of these near-liquidus phases. The settling of these phases can reduce the melter life. Hence understanding the crystallization of these crystalline phases is important in predicting the behavior of the HLW glasses in the melter environment. Representative HLW glasses were selected and heat treated at different temperatures and times. The compositions of the glassy phase, composition, morphology and volume fraction of the crystalline phases have been analyzed to understand thermodynamics and kinetics of crystallization of these near liquidus phases. The spinel compounds observed in HLW glasses exhibit extensive solid solution ranges depending on the temperature and glass composition, with Cr/Rh-rich spinels at one end, favored at higher temperatures and Fe-Cr spinels at the other end. For the first time Rh-containing spinel (up to 48 wt% Rh2 O3) has been identified as a liquidus phase. This Rh-rich spinel crystallization increases the liquidus temperature by about 150--200°C, even though Rh2O3 is present as low as 0.05wt%. The economic impact of this is huge. Using the transformation-time data measured at different temperatures for Zr, Th or U compounds, kinetic parameters were modeled using Avrami equation. Isokinetic crystallization is observed for baddeleyite and thorianite while non-isokinetic behavior is observed for zircon and parakeldyshite. Presence of a significant second phase or dramatic change in the morphology strongly influences the crystallization kinetics. The kinetic parameters depend on the liquidus phase, its volume fraction and temperature. The kinetic parameters obtained for crystallization of Zr, Th and U oxides or silicates can be used for designing HLW glass formulation as well as testing parameters.

Annamalai, Sezhian

115

Structural study of phosphorus oxynitride glasses LiNaPbPON by nuclear magnetic resonance and X-ray photoelectron spectroscopy  

Microsoft Academic Search

The structure of Li0.25Na0.25Pb0.25PO3?3x\\/2Nx (0glasses has been studied by nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS). 31P magic angle spinning (MAS) NMR shows that the glass network is built up of PO4, PO3N and PO2N2 tetrahedral units. PO4–PO4, PO4–PO3N and PO3N–PO2N2 connections, characterized with double quantum (DQ) 31P MAS NMR, are homogeneously distributed within the glass

Francisco Muñoz; Luis Pascual; Alicia Durán; Lionel Montagne; Gérard Palavit; René Berjoan; Roger Marchand

2003-01-01

116

Minor component study for simulated high-level nuclear waste glasses (Draft)  

SciTech Connect

Hanford Site single-shell tank (SSI) and double-shell tank (DSI) wastes are planned to be separated into low activity (or low-level waste, LLW) and high activity (or high-level waste, HLW) fractions, and to be vitrified for disposal. Formulation of HLW glass must comply with glass processibility and durability requirements, including constraints on melt viscosity, electrical conductivity, liquidus temperature, tendency for phase segregation on the molten glass surface, and chemical durability of the final waste form. A wide variety of HLW compositions are expected to be vitrified. In addition these wastes will likely vary in composition from current estimates. High concentrations of certain troublesome components, such as sulfate, phosphate, and chrome, raise concerns about their potential hinderance to the waste vitrification process. For example, phosphate segregation in the cold cap (the layer of feed on top of the glass melt) in a Joule-heated melter may inhibit the melting process (Bunnell, 1988). This has been reported during a pilot-scale ceramic melter run, PSCM-19, (Perez, 1985). Molten salt segregation of either sulfate or chromate is also hazardous to the waste vitrification process. Excessive (Cr, Fe, Mn, Ni) spinel crystal formation in molten glass can also be detrimental to melter operation.

Li, H.; Langowskim, M.H.; Hrma, P.R.; Schweiger, M.J.; Vienna, J.D.; Smith, D.E.

1996-02-01

117

Kinetics of Cold-Cap Reactions for Vitrification of Nuclear Waste Glass Based on Simultaneous Differential Scanning Calorimetry - Thermogravimetry (DSC-TGA) and Evolved Gas Analysis (EGA)  

SciTech Connect

For vitrifying nuclear waste glass, the feed, a mixture of waste with glass-forming and modifying additives, is charged onto the cold cap that covers 90-100% of the melt surface. The cold cap consists of a layer of reacting molten glass floating on the surface of the melt in an all-electric, continuous glass melter. As the feed moves through the cold cap, it undergoes chemical reactions and phase transitions through which it is converted to molten glass that moves from the cold cap into the melt pool. The process involves a series of reactions that generate multiple gases and subsequent mass loss and foaming significantly influence the mass and heat transfers. The rate of glass melting, which is greatly influenced by mass and heat transfers, affects the vitrification process and the efficiency of the immobilization of nuclear waste. We studied the cold-cap reactions of a representative waste glass feed using both the simultaneous differential scanning calorimetry thermogravimetry (DSC-TGA) and the thermogravimetry coupled with gas chromatography-mass spectrometer (TGA-GC-MS) as complementary tools to perform evolved gas analysis (EGA). Analyses from DSC-TGA and EGA on the cold-cap reactions provide a key element for the development of an advanced cold-cap model. It also helps to formulate melter feeds for higher production rate.

Rodriguez, Carmen P. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); ; Pierce, David A. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); ; Schweiger, Michael J. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); ; Kruger, Albert A. [USDOE Office of River Protection, Richland, WA (United States); Chun, Jaehun [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); ; Hrma, Pavel R. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States);

2013-12-03

118

Nuclear magnetic resonance studies of alkaline earth phosphosilicate and aluminoborosilicate glasses  

Microsoft Academic Search

The 11B, 27Al, 29Si and 31P magic angle spinning (MAS) NMR spectra of MO–P2O5, MO–SiO2–P2O5 and MO(M?2O)–SiO2–Al2O3–B2O3 (M=Mg, Ca, Sr and Ba, M?=Na) glasses were examined. In binary MO–P2O5 (M=Ca and Mg) glasses, the distributions of the phosphate sites, P(Qn), can be expressed by a theoretical prediction that P2O5 reacts quantitatively with MO. In the ternary 0.30MO–0.05SiO2–0.65P2O5 glasses, the 6-coordinated

Hiroshi Yamashita; Hidetake Yoshino; Keishi Nagata; Hyuma Inoue; Takeshi Nakajin; Takashi Maekawa

2000-01-01

119

Development and testing of matrices for the encapsulation of glass and ceramic nuclear-waste forms  

NASA Astrophysics Data System (ADS)

The results of research on the matrix encapsulation of high level wastes over the past few years are discussed. The demonstrations and tests described were designed to illustrate how the waste materials are effected when encapsulated in an inert matrix. Candidate materials evaluated for potential use as matrices for encapsulation of pelletized ceramics or glass marbles were categorized into four groups: metals, glasses, ceramics, and graphite. Two processing techniques, casting and hot pressing, were investigated as the most promising methods of formation or densification of the matrices. The major results deal with the development aspects. However, chemical durability tests (leach tests) of the matrix materials themselves and matrix-waste form composites are also reported. Matrix waste forms can provide a low porosity, waste-free barrier resulting in increased leach protection, higher impact strength and improved thermal conductivity compared to unencapsulated glass or ceramic waste materials.

Wald, J. W.; Brite, D. W.; Gurwell, W. E.; Buckwalter, C. Q.; Bunnell, L. R.; Gray, W. J.; Blair, H. T.; Rusin, J. M.

1982-02-01

120

Deuteron NMR (Nuclear Magnetic Resonance) in relation to the glass transition in polymers  

NASA Technical Reports Server (NTRS)

H-2NMR is introduced as a tool for investigating slow molecular motion in the glass transition region of amorphous polymers. In particular, we compare H-2 spin alignment echo spectra of chain deuterated polystyrene with model calculations for restricted rotational Brownian motion. Molecular motion in the polyztyrene-toluene system has been investigated by analyzing H-2NMR of partially deuterated polystyrene and toluene, respectively. The diluent mobility in the mixed glass has been decomposed into solid and liquid components where the respective average correlation times differ by more than 5 decades.

Roessler, E.; Sillescu, H.; Spiess, H. W.; Wallwitz, R.

1983-01-01

121

An Investigation into the Oxidation State of Molybdenum in Simplified High Level Nuclear Waste Glass Compositions  

E-print Network

for glasses containing a full simulated HLW stream are that the formation of detrimental crystalline phases containing Mo6+ upon heat treatment may be avoided by reducing the oxidation state of Mo during melting and the vitrification process should be optimised in order to minimise its formation. Experiments were performed using

Sheffield, University of

122

New functionality of chalcogenide glasses for radiation sensing of nuclear wastes.  

PubMed

Data about gamma radiation induced effects in Ge40Se60 chalcogenide thin films and radiation induced silver diffusion within these are presented. Blanket films and devices were created to study the structural changes, diffusion products, and device performance. Raman spectroscopy, X-ray diffraction, current vs. voltage (I-V) and impedance measurements expound the behavior of Ge40Se60 glass and silver diffusion within this glass under radiation. Raman study shows that there is a decrease in the area ratio between edge shared and corner shared structural units revealing structural reorganization occurring in the glasses as a result of gamma radiation. X-ray diffraction studies revealed that with sufficiently radiation dose it is also possible to create Ag2Se in selenium-depleted systems. Oxidation of the Ge enriched chalcogenide backbone is confirmed through the electrical performance of the sensing elements based on these films. Combination of these structural and diffusion products influences the device performance. The I-V behavior is characterized by increase in current and then stabilization as a function of radiation dose. Additionally, device modeling is also presented using Silvaco software and analytical methods to shed light on the device behavior. This type of sensor design and material characterizations facilitate in improving the radiation sensing capabilities of silver containing chalcogenide glass thin films. PMID:24332317

Ailavajhala, M S; Gonzalez-Velo, Y; Poweleit, C D; Barnaby, H J; Kozicki, M N; Butt, D P; Mitkova, M

2014-03-30

123

ANNUAL REPORT. IRON PHOSPHATE GLASSES: AN ALTERNATIVE FOR VITRIFYING CERTAIN NUCLEAR WASTES  

EPA Science Inventory

The two multifaceted objectives of this research project are to (1) investigate the feasibility of vitrifying 2 or 3 high priority wastes, as identified by the Tank Focus Area group, using iron phosphate glasses (i.e., determine chemical durability as a function of waste loading,...

124

CORROSION OF NUCLEAR WASTE GLASSES IN NON-SATURATED CONDITIONS: TIME-TEMPERATURE BEHAVIOUR  

E-print Network

term natural tests. These demonstrated diminishing of release rates of radionuclides by time. Corrosion by the congruent dissolution of glass controlled by hydrolysis. The transition from one mechanism of corrosion may corrode in actual conditions both via ion exchange/interdiffusion and dissolution depending

Sheffield, University of

125

Effect of Alumina Source on the Rate of Melting Demonstrated with Nuclear Waste Glass Batch  

SciTech Connect

The melting behaviors of three glass batches formulated to vitrify high-level waste were compared. These batches, otherwise identical, differed in the alumina source: one was prepared with corundum (Al2O3), another with gibbsite [Al(OH)3], and the other with boehmite [AlO(OH)]. Batch samples, in the form of loose batches or pressed pellets, were heated at 5°C/min up to 1200°C. The expansion of pellets was monitored photographically. Quenched samples of batches, heated in crucibles, were thin-sectioned, investigated with optical microscopy, and analyzed with X-ray diffraction to quantify crystalline phases. Finally, batch-to-glass conversion was investigated with thermal analysis. Corundum was still present in one batch up to 900°C whereas gibbsite and boehmite dissolved below 500°C. In the batch with corundum, quartz, the source of silica, dissolved marginally earlier than in the batches with gibbsite and boehmite. Unlike the batch with corundum that exhibited considerable foaming, the batches with gibbsite and boehmite did not produce primary foam and made a more homogeneous glass. The occurrence of primary foam in the batch with corundum is a likely cause of a low rate of melting within the cold cap of a large-scale electric melter.

Pierce, David A.; Hrma, Pavel R.; Marcial, Jose; Riley, Brian J.; Schweiger, Michael J.

2012-03-30

126

Development of a device for helium thermal diffusion investigations by IBA in self-irradiated nuclear glass  

NASA Astrophysics Data System (ADS)

To minimize the amount of nuclear waste issuing from the nuclear power plants, the solution adopted in France consists in the reprocessing of spent fuel to isolate long lived and high level radioactive waste (minor actinides and fission products). They are incorporated into a glassy matrix in order to be placed in dedicated long-term disposal repository. The confinement of the radioelements depends strongly on the integrity of the glassy matrix which could be damaged by the radiations and the generation of helium produced by ?-decays of the minor actinides. In the past few years, several studies were conducted in order to understand the behaviour of helium, especially its thermal diffusion into the glassy matrix [1-3]. However none were conducted on self-irradiated samples and a validation on radioactive glasses and in the temperature range of the repository conditions is still needed. For this purpose, a specific setup was developed on the analysis chamber of the nuclear microprobe dedicated to radioactive samples in Saclay [4]. The temperature of the sample is controlled during all the experiment, in the range from 143 to 323 K; 3He ions are implanted at low temperature. Helium profiles are measured at low temperature using the 3He(d,p)4He reaction, as-implanted and after several stages of annealing. We will present the developed setup and show the preliminary results of the measurements made on non-active samples.

Raepsaet, C.; Peuget, S.; Khodja, H.; Gutierrez, G.; Hoarau, J.; Sauvage, T.

2014-07-01

127

Direct conversion of surplus fissile materials, spent nuclear fuel, and other materials to high-level-waste glass  

SciTech Connect

With the end of the cold war the United States, Russia, and other countries have excess plutonium and other materials from the reductions in inventories of nuclear weapons. The United States Academy of Sciences (NAS) has recommended that these surplus fissile materials (SFMs) be processed so they are no more accessible than plutonium in spent nuclear fuel (SNF). This spent fuel standard, if adopted worldwide, would prevent rapid recovery of SFMs for the manufacture of nuclear weapons. The NAS recommended investigation of three sets of options for disposition of SFMs while meeting the spent fuel standard: (1) incorporate SFMs with highly radioactive materials and dispose of as waste, (2) partly burn the SFMs in reactors with conversion of the SFMs to SNF for disposal, and (3) dispose of the SFMs in deep boreholes. The US Government is investigating these options for SFM disposition. A new method for the disposition of SFMs is described herein: the simultaneous conversion of SFMs, SNF, and other highly radioactive materials into high-level-waste (HLW) glass. The SFMs include plutonium, neptinium, americium, and {sup 233}U. The primary SFM is plutonium. The preferred SNF is degraded SNF, which may require processing before it can be accepted by a geological repository for disposal.

Forsberg, C.W.; Elam, K.R.

1995-01-31

128

Quantitative fluid inclusion gas analysis of airburst, nuclear, impact and fulgurite glasses.  

SciTech Connect

We present quantitative fluid inclusion gas analysis on a suite of violently-formed glasses. We used the incremental crush mass spectrometry method (Norman & Blamey, 2001) to analyze eight pieces of Libyan Desert Glass (LDG). As potential analogues we also analyzed trinitite, three impact crater glasses, and three fulgurites. The 'clear' LDG has the lowest CO{sub 2} content and O{sub 2}/Ar ratios are two orders of magnitude lower than atmospheric. The 'foamy' glass samples have heterogeneous CO{sub 2} contents and O{sub 2}/Ar ratios. N{sub 2}/Ar ratios are similar to atmospheric (83.6). H{sub 2} and He are elevated but it is difficult to confirm whether they are of terrestrial or meteoritic origin. Combustion cannot account for oxygen depletion that matches the amount of CO{sub 2} produced. An alternative mechanism is required that removes oxygen without producing CO{sub 2}. Trinitite has exceedingly high CO{sub 2} which we attribute to carbonate breakdown of the caliche at ground zero. The O{sub 2}/Ar ratio for trinitite is lower than atmospheric but higher than all LDG samples. N{sub 2}/Ar ratios closely match atmospheric. Samples from Lonar, Henbury and Aouelloul impact craters have atmospheric N{sub 2}/Ar ratios. O{sub 2}/Ar ratios at Lonar and Henbury are 9.5 to 9.9 whereas the O{sub 2}/Ar ratio is 0.1 for the Aouelloul sample. In most fulgurites the N{sub 2}/Ar ratio is higher than atmospheric, possibly due to interference from CO. Oxygen ranges from 1.3 to 19.3%. Gas signatures of LDG inclusions neither match those from the craters, trinitite nor fulgurites. It is difficult to explain both the observed depletion of oxygen in the LDG and a CO{sub 2} level that is lower than it would be if the CO{sub 2} were simply a product of hydrocarbon combustion in air. One possible mechanism for oxygen depletion is that as air turbulently mixed with a hot jet of vaporized asteroid from an airburst and expanded, the atmospheric oxygen reacted with the metal vapor to form metal oxides that condensed. This observation is compatible with the model of Boslough & Crawford (2008) who suggest that an airburst incinerates organic materials over a large area, melting surface materials that then quench to form glass. Bubbles would contain a mixture of pre-existing atmosphere with combustion products from organic material and products of the reaction between vaporized cosmic materials (including metals) and terrestrial surface and atmosphere.

Parnell, John (University of Aberdeen, Aberdeen, UK); Newsom, Horton E. (University of New Mexico, Albuquerque, NM); Blamey, Nigel J. F. (New Mexico Tech, Socorro, NM); Boslough, Mark Bruce Elrick

2010-10-01

129

Lithium, boron and beryllium in volcanic glasses and minerals studied by nuclear microprobe  

Microsoft Academic Search

The detection of lithium, boron and beryllium was performed using a nuclear microprobe. The ?-emission yields have been measured for the most favourable nuclear reactions: 7Li(?, ???)7Li, 7Li(p, p??)7Li, 10B(p, ??)7Be and 7Li(p, n?)7Be. The possible interferences and the minimum detection limits (MDL) are presented, at different energies and for a total integrated charge of 1 ?C. Lithium and boron,

S. Rio; N. Métrich; M. Mosbah; P. Massiot

1995-01-01

130

Pr{sup 3+}-doped fluoro-oxide lithium glass as scintillator for nuclear fusion diagnostics  

SciTech Connect

Experimental results are presented on the neutron scintillating properties of a custom-designed Pr3+(praseodymium)-doped lithium (Li) glass. Luminescence was observed at 278 nm wavelength, originating from the 5d-4f transition. Time-resolved measurements yielded about 20 ns decay times for ultraviolet and x-ray excitation while much faster decay times of about 6 ns were observed for alpha particle and neutron excitation. Actual time-of-flight data in laser fusion experiments at the GEKKO XII facility of the Institute of Laser Engineering, Osaka University reveal that it can clearly discriminate fusion neutrons from the much stronger x-rays signals. This material can promise improved accuracy in future scattered neutron diagnostics.

Arikawa, Yasunobu; Yamanoi, Kohei; Nakazato, Tomoharu; Estacio, Elmer Surat; Shimizu, Toshihiko; Sarukura, Nobuhiko; Nakai, Mitsuo; Norimatsu, Takayoshi; Azechi, Hiroshi [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Murata, Takahiro [Department of Chemistry, School of Science, Tokai University, Kawayou, Minamiaso, Aso, Kumamoto 869-1404 (Japan); Fujino, Shigeru [Department of Materials Process Engineering, Graduate School of Engineering, Kyushu University, 744 Nishikyo Motooka, Fukuoka 819-0395 (Japan); Yoshida, Hideki [Ceramic Research Center of Nagasaki, Hiekoba, Hasami, Higashisonogi, Nagasaki 859-3726 (Japan); Kamada, Kei; Usuki, Yoshiyuki [Furukawa Co., Ltd., Kannondai, Tsukuba, Ibaraki 1-25-13 (Japan); Suyama, Toshihisa [Tokuyama Corporation Shibuya, 3-3-1, Shibuya, Tokyo 150-8383 (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoyou, Sendai, Miyagi 980-8577 (Japan); Sato, Nakahiro; Kan, Hirofumi [Central Research Laboratory, Hamamatsu Photonics K. K., 5000 Hiraguchi, Hamakitaku, Hamamatsu, Shizuoka 434-8601 (Japan)

2009-11-15

131

CHEMICAL DECOMPOSITION OF HIGH-LEVEL NUCLEAR WASTE STORAGE/DISPOSAL GLASSES UNDER IRRADIATION  

EPA Science Inventory

The Offices of Energy Research and Environmental Management are immediately concerned with the development of storage/immobilization media for high-level nuclear wastes and excess weapons plutonium. These media must be stable and free of risk to the public or to the environment f...

132

Effect of nuclear quadrupole interactions on the dynamics of two-level systems in glasses.  

PubMed

The standard tunneling model describes quite satisfactorily the properties of amorphous solids at temperatures T < 1K in terms of an ensemble of two-level systems including the logarithmic temperature dependence of the dielectric constant. Yet, experiments have shown that at ultralow temperatures T< 5 mK such a temperature behavior breaks down and the dielectric constant becomes temperature independent (plateau effect). In this Letter we suggest an explanation of this behavior exploiting the effect of the nuclear quadrupole interaction on tunneling. We also predict that the application of a sufficiently large magnetic field B> 10T should restore the logarithmic dependence because of the suppression of the nuclear quadrupole interaction. PMID:16486595

Burin, A L; Polishchuk, I Ya; Fulde, P; Sereda, Y

2006-01-20

133

Radioisotope generators for nuclear medicine based on Fajans adsorption on glass microspheres  

SciTech Connect

Several radioisotope generator systems exist in which the carrier-free daughter product would precipitate if present in macro amounts at pH levels at which the parent is soluble. Included among these are the {sup 68}Ge/{sup 68}Ga, {sup 90}Sr/{sup 90}Y, and {sup 47}Ca/{sup 47}Sc pairs. This paper reveals that in these systems, chemical separation can be achieved by Fajans adsorption of the radiocolloidal daughter products onto surfaces such as activated glass microspheres at an appropriate pH. This is followed by washing to remove the parent solution and desorption of the daughter crop by acid washes. Investigation of the Ge/Ga and Sr/Y systems demonstrated that this solid-phase extraction method is erratic, but can give daughter yields as high at 89% with separation factors up to {approximately} 10,000 form parent isotope. This method has the potential for producing daughter isotopes with a minimum of metal and organic impurities for labeling cells, receptor binding ligands, and antibodies for diagnostic and radiotherapeutic purposes.

Ehrhardt, G.J.; Symes, S.; Guimon, R.K.; Zinn, K.R. (Univ. of Missouri, Research Reactor, Columbia, MO (US))

1992-04-01

134

Quasicrystalline Approach to Prediting the Spinel-Nepheline Liquidus: Application to Nuclear Waste Glass Processing  

SciTech Connect

The crystal-melt equilibria in complex fifteen component melts are modeled based on quasicrystalline concepts. A pseudobinary phase diagram between acmite (which melts incongruently to a transition metal ferrite spinel) and nepheline is defined. The pseudobinary lies within the Al{sub 2}O{sub 3}-Fe{sub 2}O{sub 3}-Na{sub 2}O-SiO{sub 2} quaternary system that defines the crystallization of basalt glass melts. The pseudobinary provides the partitioning of species between the melt and the primary liquidus phases. The medium range order of the melt and the melt-crystal exchange equilibria are defined based on a constrained mathematical treatment that considers the crystallochemical coordination of the elemental species in acmite and nepheline. The liquidus phases that form are shown to be governed by the melt polymerization and the octahedral site preference energies. This quasicrystalline liquidus model has been used to prevent unwanted crystallization in the world's largest high level waste (HLW) melter for the past three years while allowing >10 wt% higher waste loadings to be processed.

Jantzen, Carol

2005-10-10

135

Thermal Conductivity of Glasses Induced by Nuclear Quadrupole Interaction at Ultra Low Temperatures  

NASA Astrophysics Data System (ADS)

It is investigated how nuclear degrees of freedom of tunneling system (TS) inherent in amorphous solids influence its acoustic properties. It was shown in our previous papers that below 10 mK nuclear quadrupole interaction breaks down the coherent tunneling. This phenomenon results in appearance of the quasi-gap in the distribution function for the tunneling amplitude splitting. The quasi-gap is responsible for the plateau in the temperature dependence of the real part of a dielectric permittivity or speed of sound. In this paper we are interested in ultrasonic absorption and thermal conductivity which are intimately connected. We demonstrate that there exists a temperature interval in a millikelvin region where the sound absorption behavior changes drastically from the behavior predicted by the standard tunneling model (STM). In particular, the sound absorption increases approximately by an order of magnitude. Since in the millikelvin region the heat transport is due to acoustic phonons, the thermal conductivity also should demonstrate a strong increase as compared to standard tunneling model. The application of a strong magnetic field is known to restore the coherent tunneling and the standard distribution for the tunneling splitting amplitude. Thus, one can expect that in a strong magnetic field the thermal conductivity should drop in the temperature interval where the coherent tunneling was initially destroyed.

Polishchuk, I. Y.; Burin, A. L.

2011-03-01

136

Micro-fluidics and integrated optics glass sensor for in-line micro-probing of nuclear samples  

SciTech Connect

We study the miniaturisation of Thermal Lens Spectrometry (TLS) towards Lab-on-chip integration in order to reduce the volume of fluid assays in nuclear process control. TLS is of great interest in this context since it combines the advantages of optical detection methods with an inherent suitability for small-scale samples. After validating the experimental principle in a classical thermal lens crossed-beam setup, we show the integration of a Young-interferometer with a microcapillary on a glass substrate, reducing the necessary sample size to 400 nl. The interferometer translates the photo-thermally induced refractive index change in the fluid to a phase shift of the fringe pattern, which can then be detected by a camera. Measurements of Co(II) in ethanol yield a detection limit of c = 5 x 10{sup -4} M for the crossed-beam setup and c = 6x10{sup -3} M for the integrated sensor. At an interaction length of 10 {mu}m, it detects a minimum absorbance of AU = 6 x 10{sup -5} in a probed volume of 10 pl. (authors)

Schimpf, A. [Institut de Microelectronique, Electromagnetisme et Photonique IMEP-LAHC Minatec, Batiment INP Grenoble, 3, parvis Louis Neel, BP 257, 38016 Cedex 1 (France); Canto, F. [Commissariat a l'Energie Atomique CEA de Marcoule, DEN - DRCP - SEAA - LAMM, BP17171, 30207 Bagnols sur Ceze Cedex (France); Bucci, D. [Institut de Microelectronique, Electromagnetisme et Photonique IMEP-LAHC Minatec, Batiment INP Grenoble, 3, parvis Louis Neel, BP 257, 38016 Cedex 1 (France); Magnaldo, A.; Couston, L. [Commissariat a l'Energie Atomique CEA de Marcoule, DEN - DRCP - SEAA - LAMM, BP17171, 30207 Bagnols sur Ceze Cedex (France); Broquin, J. E. [Institut de Microelectronique, Electromagnetisme et Photonique IMEP-LAHC Minatec, Batiment INP Grenoble, 3, parvis Louis Neel, BP 257, 38016 Cedex 1 (France)

2011-07-01

137

Micro-fluidics and integrated optics glass sensor for in-line micro-probing of nuclear samples  

SciTech Connect

We study the miniaturization of Thermal Lens Spectrometry (TLS) towards Lab-on-chip integration in order to reduce the volume of fluid assays in nuclear process control. TLS is of great interest in this context since it combines the advantages of optical detection methods with an inherent suitability for small-scale samples. After validating the experimental principle in a classical thermal lens crossed-beam setup, we show the integration of a Young-interferometer with a microcapillary on a glass substrate, reducing the necessary sample size to 400 nl. The interferometer translates the photo-thermally induced refractive index change in the fluid to a phase shift of the fringe pattern, which can then be detected by a camera. Measurements of Co(II) in ethanol yield a detection limit of c = 5 x 10{sup -4} M for the crossed-beam setup and c = 6 x 10{sup -3} M for the integrated sensor. At an interaction length of 10 m, it detects a minimum absorbance of K = 1.2 x 10{sup -4} in a probed volume of 14 pl. (authors)

Schimpf, A.; Bucci, D.; Broquin, J.E. [Minatec, Inst Microelect Electromagnetisme et Photon IMEP L, F-38016 Grenoble 1, (France); Canto, F.; Magnaldo, A.; Couston, L. [Commissariat Energie Atom Marcoule, DEN-DRCP, F-30207 Bagnols Sur Ceze, (France)

2012-08-15

138

Local structures of mesoporous bioactive glasses and their surface alterations in vitro: inferences from solid-state nuclear magnetic resonance  

PubMed Central

We review the benefits of using 29Si and 1H magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy for probing the local structures of both bulk and surface portions of mesoporous bioactive glasses (MBGs) of the CaO–SiO2?(P2O5) system. These mesoporous materials exhibit an ordered pore arrangement, and are promising candidates for improved bone and tooth implants. We discuss experimental MAS NMR results from three MBGs displaying different Ca, Si and P contents: the 29Si NMR spectra were recorded either directly by employing radio-frequency pulses to 29Si, or by magnetization transfers from neighbouring protons using cross polarization, thereby providing quantitative information about the silicate speciation present in the pore wall and at the MBG surface, respectively. The surface modifications were monitored for the three MBGs during their immersion in a simulated body fluid (SBF) for intervals between 30 min and one week. The results were formulated as a reaction sequence describing the interconversions between the distinct silicate species. We generally observed a depletion of Ca2+ ions at the MBG surface, and a minor condensation of the silicate-surface network over one week of SBF soaking. PMID:22349247

Gunawidjaja, Philips N.; Mathew, Renny; Lo, Andy Y. H.; Izquierdo-Barba, Isabel; García, Ana; Arcos, Daniel; Mattias Edén, María Vallet-Regí

2012-01-01

139

Phosphorus oxynitride glasses  

Microsoft Academic Search

The properties and structural role of nitrogen in phosphorus oxynitride glasses are reported. Properties summarized for several compositions include the dissolution rate in water, thermal expansion coefficient, viscosity and refractive index. The bonding and coordination number of nitrogen in the glass network has been deduced from nuclear magnetic resonance, X-ray photoelectron spectroscopy and Raman spectroscopy. The existing evidence shows that

Mary R. Reidmeyer; Delbert E. Day

1995-01-01

140

Glass science tutorial: Lecture No. 7, Waste glass technology for Hanford  

SciTech Connect

This paper presents the details of the waste glass tutorial session that was held to promote knowledge of waste glass technology and how this can be used at the Hanford Reservation. Topics discussed include: glass properties; statistical approach to glass development; processing properties of nuclear waste glass; glass composition and the effects of composition on durability; model comparisons of free energy of hydration; LLW glass structure; glass crystallization; amorphous phase separation; corrosion of refractories and electrodes in waste glass melters; and glass formulation for maximum waste loading.

Kruger, A.A.

1995-07-01

141

Material interactions relating to long-term geologic disposal of nuclear waste glass. [After 300 to 1000 years  

Microsoft Academic Search

This review paper systematizes the additional interactions that materials in a geologic repository will impose on the borosilicate glass waste form-groundwater interactions. These materials are the steel canister that holds the glass, the steel overpack over the canister, backfill materials that may be used, and last, the repository host rock. The repository geologies reviewed are tuff, salt, basalt, and granite.

N. E. Bibler; C. M. Jantzen

1986-01-01

142

INTERNATIONAL STUDIES OF ENHANCED WASTE LOADING AND IMPROVED MELT RATE FOR HIGH ALUMINA CONCENTRATION NUCLEAR WASTE GLASSES  

SciTech Connect

The goal of this study was to determine the impacts of glass compositions with high aluminum concentrations on melter performance, crystallization and chemical durability for Savannah River Site (SRS) and Hanford waste streams. Glass compositions for Hanford targeted both high aluminum concentrations in waste sludge and a high waste loading in the glass. Compositions for SRS targeted Sludge Batch 5, the next sludge batch to be processed in the Defense Waste Processing Facility (DWPF), which also has a relatively high aluminum concentration. Three frits were selected for combination with the SRS waste to evaluate their impact on melt rate. The glasses were melted in two small-scale test melters at the V. G. Khlopin Radium Institute. The results showed varying degrees of spinel formation in each of the glasses. Some improvements in melt rate were made by tailoring the frit composition for the SRS feeds. All of the Hanford and SRS compositions had acceptable chemical durability.

Fox, K; David Peeler, D; James Marra, J

2008-09-11

143

Intrinsic dosimetry of glass containers used to transport nuclear materials: Potential implications to the fields of waste management and nuclear forensics  

SciTech Connect

Thermoluminescence (TL) and Electron Paramagnetic Resonance (EPR) dosimetry were used to measure dose effects in borosilicate glass with time, from 10 min to w60 days following exposure to a dose of up to 100 Gy. TL and EPR results were consistent and performed similarly, with both techniques capable of achieving an estimated limit of detection of between 0.5 and 1 Gy. Three peaks were identified in the TL glow curve at roughly 110 C, 205 C, and 225 C. The intensity of the 205 C peak was the dominant peak over the time period of this study. The stability of all of the peaks with time since irradiation increased with their corresponding temperature and no significant variation was observed in the glow curve response to a specified total dose attained at different dose rates. The intensity of the 205 C peak decreased logarithmically with time regardless of total dose. Based upon a conservative limit of detection of 3.3 Gy, a 100 Gy dose would still be detected 2.7E3 years after exposure. Here, we introduce the concept of intrinsic dosimetry, the measurement of the total absorbed dose received by the walls of a container containing radioactive material. The foreseen advantage of intrinsic dosimetry comes from considering the measured absorbed dose received by containers in concert with the characteristics (amount, type) of the source of that dose, the radioactive material contained within the walls of the container, in order to provide enhanced information about the history of an unknown sample in question. Three hypothetical scenarios are presented to introduce this method and to illustrate how intrinsic dosimetry might benefit the fields of nuclear forensics and waste management.

Schwantes, Jon M.; Miller, Steve D.; Piper, Roman K.; Murphy, Mark K.; Amonette, James E.; Bonde, Steven E.; Duckworth, Douglas C.

2009-04-12

144

A 25-year laboratory experiment on French SON68 nuclear glass leached in a granitic environment - First investigations  

NASA Astrophysics Data System (ADS)

We have investigated a 25.75-year old leaching experiment to improve our understanding of the mechanisms controlling glass dissolution in geological disposal conditions. A SON68 glass block was leached in slowly renewed synthetic groundwater (at 90 °C, 100 bar) in contact with some pieces of granite and Ni-Cr-Mo alloy as environmental storage materials. One hundred and sixty-three samplings were carried out over the entire duration of the experiment and were used to calculate the mean thickness of the altered glass (28 (±9) ?m) and the glass dissolution rate. After few months, the rate remained very constant at 6 × 10 -3 g m -2 d -1 which is about 20 times higher than the residual rate measured in a batch reactor at the same temperature. At the end of the experiment, mainly SEM analyses were performed on the entire glass block. Surprisingly, the glass alteration layer has neither a homogeneous thickness, nor a homogeneous morphology. The location of the sampling valve (at half height of the glass block) seems to divide the glass block into two parts. In the upper half (above the sampling valve), the general morphology of the alteration layer consists in a relatively simple and uniform gel and some secondary phases which are rare-earth phosphates. The mean measured thickness of this alteration layer is 6.7 (±0.3) ?m. However, in the lower half of the glass block, the gel is globally larger and frequently contains rounded shapes which are rare-earth phosphates. This section is edged by secondary phases bearing Mg, Na, Zn and Ni. The mean measured thickness is 81.3 (±1.1) ?m in the lower half. In this experiment, the flow rate which leads to the hydrodynamic transport of the soluble species must be a key factor for the local glass alteration process. We have also shown that this unexpected behavior is likely due to heterogeneities of the chemistry of the solution. This conclusion is supported by the behavior of Mg. This element, supplied by the inlet solution, precipitates with Si and forms clay minerals and therefore weakens the passivating properties of the gel. Mg-rich clay minerals are only observed in the lower half of the glass block. Further investigations are necessary to better understand the coupling between the hydrodynamics and chemistry in this experiment. However, based on this study, we can conclude that glass in disposal should be very sensitive to the water renewal near the glass surface.

Guittonneau, C.; Gin, S.; Godon, N.; Mestre, J. P.; Dugne, O.; Allegri, P.

2011-01-01

145

Secondary phase formation and the microstructural evolution of surface layers during vapor phase alteration of the French SON 68 nuclear waste glass at 200{degrees}C  

SciTech Connect

The SON 68 inactive {open_quotes}R7T7{close_quotes} composition is the French reference glass for the LWR nuclear waste glass. Vapor phase alteration was used to accelerate the reaction progress of glass corrosion and to develop the characteristic suite of secondary, alteration phases. Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six inactive R7T7 waste glasses which were altered in the presence of saturated water vapor (200{degrees}C) for 91, 241, 908, 1000, 1013, and 1021 days. The AEM samples were examined in cross-section (lattice-fringe imaging, micro-diffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered with a thin altered rind. The layer became thicker with time: 0.5 {mu}m for 22 days; 4 {mu}m for 91 days; 6 {mu}m for 241 days; 10 {mu}m for 908 days; 26 {mu}m for 1013 days; and <35 {mu}m for 1021 days. The composite alteration layer of the SON 68 samples is at least four time less thick than that of the SRL 131 glass composition. Six distinctive zones, based on phase chemistry and microstructure, were distinguished within the well-developed surface layers. Numerous crystalline phases such as analcime, tobermorite, apatite, and weeksite were identified on the surfaces of the reacted glasses as precipitates. Two crystalline phases, Ag{sub 2}TeO{sub 3} and (Ca,Sr)Mo{sub 3}O{sub 9}(OH){sub 2}, were found within the inner zones of surface layers, and they must have nucleated in situ, indicating that Ag, Te, Sr, and Mo can be retained within the surface layer. The majority of the surface layer volume is composed of two morphologically and chemically different structures: one consists of well-crystallized fibrous smectite aggregates occurring along with cavities, the A-domain; and the other consists of poorly-crystallized regions containing needle-like smectite (montmorillonite) crystallites, a silica-rich amorphous matrix, and possibly ZrO{sub 2} particles, the B-domain.

Gong, W.L.; Ewing, R.C.; Wang, L.M. [Univ. of New Mexico, Albuquerque, NM (United States)] [and others

1995-12-31

146

Application of EQ3/6 to modeling of nuclear waste glass behavior in a tuff repository  

SciTech Connect

Modeling of glass degradation based on sound geochemical principles appears to be possible with revisions to EQ3/6. Realistic source terms for several repository scenarios may be generated with such a model. One scenario which appears very likely and which is also amenable to modeling using EQ3/6 is that in which an intact but perforated canister holds water in contact with waste glass. The water overflows continuously or periodically, allowing radionuclides to come in contact with repository rock. This isolated-type scenario will be the first realistic modeling effort because it limits complex interactions between rock and glass. However, EQ3/6 modeling should be possible even for very complicated scenarios if sufficient experimental data are available on rates and thermodynamics. This will be the limiting factor in progress toward modeling the complete system.

Aines, R.D.

1986-05-01

147

DEVELOPMENT OF GLASS COMPOSITIONS TO IMMOBILIZE ALKALI, ALKALINE EARTH, LANTHANIDE AND TRANSITION METAL FISSION PRODUCTS FROM NUCLEAR FUEL REPROCESSING  

SciTech Connect

The Advanced Fuel Cycle Initiative (AFCI) waste management strategy revolves around specific treatment of individual or groups of separated waste streams. A goal for the separations processes is to efficiently manage the waste to be dispositioned as high level radioactive waste. The Advanced Fuel Cycle Initiative (AFCI) baseline technology for immobilization of the lanthanide (Ln) and transition metal fission product (TM) wastes is vitrification into a borosilicate glass. A current interest is to evaluate the feasibility of vitrifying combined waste streams to most cost effectively immobilize the wastes resulting from aqueous fuel reprocessing. Studies showed that high waste loadings are achievable for the Ln only (Option 1) stream. Waste loadings in excess of 60 wt % (on a calcined oxide basis) were demonstrated via a lanthanide borosilicate (LaBS) glass. The resulting glasses had excellent relative durability as determined by the Product Consistency Test (PCT). For a combined Ln and TM waste stream glass (Option 2), noble metal solubility was found to limit waste loading. However, the measured PCT normalized elemental releases for this glass were at least an order of magnitude below that of Environmental Assessment (EA) glass. Current efforts to evaluate the feasibility of vitrifying combined Ln, TM, alkali (Cs is the primary radionuclide of concern) and alkaline earth (Sr is the primary radionuclide of concern) wastes (Option 3) have shown that these approaches are feasible. However, waste loading limitations with respect to heat load (Cs/Sr loading), molybdenum solubility and/or noble metal solubility will likely be realized and must be considered in determining the cost effectiveness of these approaches.

Marra, James C.; Billings, Amanda Y.; Crum, Jarrod V.; Ryan, Joseph V.; Vienna, John D.

2010-02-26

148

The behavior of silicon and boron in the surface of corroded nuclear waste glasses : an EFTEM study.  

SciTech Connect

Using electron energy-loss filtered transmission electron microscopy (EFTEM), we have observed the formation of silicon-rich zones on the corroded surface of a West Valley (WV6) glass. This layer is approximately 100-200 nm thick and is directly underneath a precipitated smectite clay layer. Under conventional (C)TEM illumination, this layer is invisible; indeed, more commonly used analytical techniques, such as x-ray energy dispersive spectroscopy (EDS), have failed to describe fully the localized changes in the boron and silicon contents across this region. Similar silicon-rich and boron-depleted zones were not found on corroded Savannah River Laboratory (SRL) borosilicate glasses, including SRL-EA and SRL-51, although they possessed similar-looking clay layers. This study demonstrates a new tool for examining the corroded surfaces of materials.

Buck, E. C.; Smith, K. L.; Blackford, M. G.

1999-11-23

149

Glass Works  

NSDL National Science Digital Library

This website is about glass and glass-making in Canada and it is presented by the Canadian Museum of Civilization. The site teaches visitors about natural glass, Canadian glass, practical glass, industrial glass, and inspirational glass. Before delving into the different ways glass is used in society, the website provides a thorough answer to the question "What is glass?" It is a mixture of sand, soda, and lime which is heated to extremely high temperatures, then cooled. Visitors will learn the benefits of glass, such as the fact that it is recyclable, inexpensive to produce from common materials, non-corrosive, and it also possesses the ability to be rolled, molded, blown, or cast. The "Making Glass" link shows visitors images of a glassworks furnace, an early 1900s automatic bottle-blowing machine, and a recipe for 2,000 pounds of amber-colored glass from the Dominion Glass Company. The "Practical Glass" link has photos of several objects such as a canning jar, goblet, flytrap, all of which are quite beautiful.

150

Glass Ceramic Formulation Data Package  

Microsoft Academic Search

A glass ceramic waste form is being developed for treatment of secondary waste streams generated by aqueous reprocessing of commercial used nuclear fuel (Crum et al. 2012b). The waste stream contains a mixture of transition metals, alkali, alkaline earths, and lanthanides, several of which exceed the solubility limits of a single phase borosilicate glass (Crum et al. 2009; Caurant et

Jarrod V. Crum; Carmen P. Rodriguez; John S. McCloy; John D. Vienna; Chul-Woo Chung

2012-01-01

151

Waste glass weathering  

SciTech Connect

The weathering of glass is reviewed by examining processes that affect the reaction of commercial, historical, natural, and nuclear waste glass under conditions of contact with humid air and slowly dripping water, which may lead to immersion in nearly static solution. Radionuclide release data from weathered glass under conditions that may exist in an unsaturated environment are presented and compared to release under standard leaching conditions. While the comparison between the release under weathering and leaching conditions is not exact, due to variability of reaction in humid air, evidence is presented of radionuclide release under a variety of conditions. These results suggest that both the amount and form of radionuclide release can be affected by the weathering of glass.

Bates, J.K.; Buck, E.C.

1993-12-31

152

Glass Artworks  

NASA Technical Reports Server (NTRS)

Several NASA technologies have played part in growth and cost containment of studio glass art, among them a foam type insulation developed to meet a need for lightweight material that would reduce flame spread in aircraft fire. Foam comes in several forms and is widely used by glass artists, chiefly as an insulator for the various types of ovens used in glass working. Another Spinoff is alumina crucibles to contain molten glass. Before alumina crucibles were used, glass tanks were made of firebrick which tended to erode under high temperatures and cause impurities; this not only improved quality but made the process more cost effective. One more NASA technology that found its way into glass art working is a material known as graphite board, a special form of graphite originally developed for rocket motor applications. This graphite is used to exact compound angles and creates molds for poured glass artworks of dramatic design.

1988-01-01

153

Glass Wings  

NSDL National Science Digital Library

Glass Wings has now opened its doors onto the electronic frontier. This Australian site covers a wide range of interests including news, games, entertainment, humour, travel, books and magazines, the environment, human rights, food, health, the educational, sexuality, the arts and a writers forum. Glass Wings is a companion project of Xanadu Australia.

154

Frosty Glasses  

NSDL National Science Digital Library

In this activity, learners explore why frost forms. They create their own frost using a solution of ice water and salt in a glass. The salt allows the temperature of the water to drop below the normal freezing point, so that water vapor in the air turns directly into solid ice on the surface of the glass.

Cosi

2009-01-01

155

Metallic glasses  

Microsoft Academic Search

This paper surveys the present state of knowledge concerning the production, stability and structure of metallic glasses made by rapid quenching from the melt, and outlines their principal magnetic, electrical and mechanical properties. Emphasis is placed on the influence of annealing, at temperatures below the glass transition, on a range of properties. The prospect for practical applications is examined, with

R. W. Cahn

1980-01-01

156

Glass-An Environmental Protector  

SciTech Connect

From asbestos abatement to lead paint removal to nuclear waste stabilization and even to heavy metal removal using microorganisms, glass has great potential as a solution to many environmental problems. The ability to accommodate an array of chemical elements within the glass structure has facilitated the use of glass as a medium for the stabilization of numerous hazardous substances. The resulting glasses have proven to be durable enough for direct land disposal. In many cases, the stabilized forms have been deemed suitable for re-use in other applications. As recycling and hazardous material treatment become even more important in the global materials cycle, it is a certainty that glass will assume a prominent role.

MARRA, JAMES

2004-11-01

157

Failure analysis of the lithium battery: A study of the header deposit on the cell top and diffusion within the electrode glass seal using nuclear microanalysis and FFTIR spectroscopy  

NASA Astrophysics Data System (ADS)

The Solid Rocket Booster Range Safety System (SRBRSS) uses a lithium/poly-carbon monofluoride primary battery as a source of electrical power. After cell fabrication and activation, some battery cells have shown self discharge. One possible source of this cell discharge has been suggested to be the formation and growth of a conducting crystallized chemical compound across the glass bead insulator, electrically shorting the glass bead to the casing. This laboratory has begun an analysis of this compound, the glass seal holding the cathode into place, and the cell electrolyte, using Fast Fourier Transform Infrared (FFTIR) Analysis, Rutherford Backscattering Spectroscopy (RBS), and Nuclear Reaction Microanalysis. Preliminary measurements have confirmed the existence of lithium, nitrogen, fluorine, and oxygen on a reddish-brown deposit covering parts of the glass seal holding the positive electrode in place. Cells using Li metal electrodes, have many advantages over conventional primary batteries. One principal disadvantage of using Li batteries on a commercial basis would be the environmental impact of the fluorocarbon material. Another would be the relatively high expense of (CF)n.

Hassan, Razi A.

1991-10-01

158

Failure analysis of the lithium battery: A study of the header deposit on the cell top and diffusion within the electrode glass seal using nuclear microanalysis and FFTIR spectroscopy  

NASA Technical Reports Server (NTRS)

The Solid Rocket Booster Range Safety System (SRBRSS) uses a lithium/poly-carbon monofluoride primary battery as a source of electrical power. After cell fabrication and activation, some battery cells have shown self discharge. One possible source of this cell discharge has been suggested to be the formation and growth of a conducting crystallized chemical compound across the glass bead insulator, electrically shorting the glass bead to the casing. This laboratory has begun an analysis of this compound, the glass seal holding the cathode into place, and the cell electrolyte, using Fast Fourier Transform Infrared (FFTIR) Analysis, Rutherford Backscattering Spectroscopy (RBS), and Nuclear Reaction Microanalysis. Preliminary measurements have confirmed the existence of lithium, nitrogen, fluorine, and oxygen on a reddish-brown deposit covering parts of the glass seal holding the positive electrode in place. Cells using Li metal electrodes, have many advantages over conventional primary batteries. One principal disadvantage of using Li batteries on a commercial basis would be the environmental impact of the fluorocarbon material. Another would be the relatively high expense of (CF)n.

Hassan, Razi A.

1991-01-01

159

Glass microspheres  

SciTech Connect

This patent describes a glass microsphere having a diameter of about 54 micrometers or less and adapted for radiation therapy of a mammal. The glass consists of essentially an yttrium oxide-aluminosilicate glass composition lying substantially within a quadrilateral region of the ternary composition diagram of the yttria-alumina-silica system, the quadrilateral region being defined by its four corners having the following combination of weight proportions of the components: 20% silica, 10% alumina, 70% yttria; 70% silica, 10% alumina, 20% yttria; 70% silica, 20% alumina, 10% yttria; and 20% silica, 45% alumina, 35% yttria, the glass having a chemical durability such that subsequent to irradiation and administration of the microsphere to the mammal, the mircosphere will not release a significant amount of yttrium-90 into the mammal's system.

Day, D.E.; Ehrhardt, G.J.

1988-12-06

160

Nuclear  

NSDL National Science Digital Library

What part does nuclear energy play in satisfying energy demands? This informational piece, part of a series about the future of energy, introduces students to the uranium atom as an energy source. Here students read about the history of nuclear energy, how energy is derived from uranium, and benefits of nuclear energy. Information is also provided about limitations, particularly disposal problems and radioactivity, and geographical considerations of nuclear power in the United States. Thought-provoking questions afford students chances to reflect on what they've read about the uses of nuclear power. Articles and information on new nuclear plant design and nuclear accidents are available from a sidebar. Five energy-related PBS NewsHour links are provided. A web link to the U.S. Nuclear Regulatory Commission is included. Copyright 2005 Eisenhower National Clearinghouse

Iowa Public Television. Explore More Project

2004-01-01

161

The use of glass matrices for solidification of radioactive wastes  

SciTech Connect

The physico-chemical aspects of the solidification of nuclear wastes have been studied at the Institute of Physical Chemistry of the Russian Academy of Sciences for a number of years. This method is viewed as the most reliable method of storage of nuclear wastes. Various glass systems have been studied, including phosphate, borosilicate glasses etc. The data obtained allow optimal glass compositions to be chosen for solidification of various nuclear wastes.

Gromov, V.V.; Minaev, A.A. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Physical Chemistry

1993-12-31

162

Weathering of glasses for solar applications  

Microsoft Academic Search

The weathering of several glasses being considered for solar applications has been studied by a number of surface characterization techniques including optical spectroscopy, optical and scanning electron microscopy, sputter-through Auger analysis, ESCA, SIMS, dye penetration testing, surface profile measurements and resonant nuclear reaction profiling. Significant weathering effects were observed only for the soda-lime-silicate glasses. For soda-lime-silicate glasses, the results indicate

J. E. Shelby; J. Vitko Jr.; C. G. Pantano

1980-01-01

163

Durability of Silicate Glasses: An Historical Approach  

SciTech Connect

We present a short review of current theories of glass weathering, including glass dissolution, and hydrolysis of nuclear waste glasses, and leaching of historical glasses from an XAFS perspective. The results of various laboratory leaching experiments at different timescales (30 days to 12 years) are compared with results for historical glasses that were weathered by atmospheric gases and soil waters over 500 to 3000 years. Good agreement is found between laboratory experiments and slowly leached historical glasses, with a strong enrichment of metals at the water/gel interface. Depending on the nature of the transition elements originally dissolved in the melt, increasing elemental distributions are expected to increase with time for a given glass durability context.

Farges, Francois; /Museum Natl. Hist. Natur. /Stanford U., Geo. Environ. Sci.; Etcheverry, Marie-Pierre; /Marne la Vallee U.; Haddi, Amine; /Marne la Valle U.; Trocellier,; /Saclay; Curti, Enzo; /PSI, Villigen; Brown, Gordon E., Jr.; /SLAC, SSRL

2007-01-02

164

Weathering of glasses for solar applications  

NASA Astrophysics Data System (ADS)

The weathering of several glasses being considered for solar applications has been studied by a number of surface characterization techniques including optical spectroscopy, optical and scanning electron microscopy, sputter-through Auger analysis, ESCA, SIMS, dye penetration testing, surface profile measurements and resonant nuclear reaction profiling. Significant weathering effects were observed only for the soda-lime-silicate glasses. For soda-lime-silicate glasses, the results indicate that the first stage of weathering is the formation of a low-density anti-reflection film on the glass surface. Growth of this film eventually results in spalling of the glass surface and severe degradation of the optical quality of the glass. Float glasses exhibit significantly better weathering resistance on their tin-rich surface than on the tin-poor surface.

Shelby, J. E.; Vitko, J., Jr.; Pantano, C. G.

1980-09-01

165

Prediction of glass durability as a function of environmental conditions  

SciTech Connect

A thermodynamic model of glass durability is applied to natural, ancient, and nuclear waste glasses. The durabilities of over 150 different natural and man-made glasses, including actual ancient Roman and Islamic glasses (Jalame ca. 350 AD, Nishapur 10-11th century AD and Gorgon 9-11th century AD), are compared. Glass durability is a function of the thermodynamic hydration free energy, ..delta..G/sub hyd/, which can be calculated from glass composition and solution pH. The durability of the most durable nuclear waste glasses examined was /approximately/10/sup 6/ years. The least durable waste glass formulations were comparable in durability to the most durable simulated medieval window glasses of /approximately/10/sup 3/ years. In this manner, the durability of nuclear waste glasses has been interpolated to be /approximately/10/sup 6/ years and no less than 10/sup 3/ years. Hydration thermodynamics have been shown to be applicable to the dissolution of glass in various natural environments. Groundwater-glass interactions relative to geologic disposal of nuclear waste, hydration rind dating of obsidians, andor other archeological studies can be modeled, e.g., the relative durabilities of six simulated medieval window glasses have been correctly predicted for both laboratory (one month) and burial (5 years) experiments. Effects of solution pH on glass dissolution has been determined experimentally for the 150 different glasses and can be predicted theoretically by hydration thermodynamics. The effects of solution redox on dissolution of glass matrix elements such as SI and B have shown to be minimal. The combined effects of solution pH and Eh have been described and unified by construction of thermodynamically calculated Pourbaix (pH-Eh) diagrams for glass dissolution. The Pourbaix diagrams have been quantified to describe glass dissolution as a function of environmental conditions by use of the data derived from hydration thermodynamics. 56 refs., 7 figs.

Jantzen, C.M.

1988-01-01

166

Phase Stability Determinations of DWPF Waste Glasses  

SciTech Connect

Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. To fulfill this requirement, glass samples were heat treated at various times and temperatures. These results will provide guidance to the repository program about conditions to be avoided during shipping, handling and storage of DWPF canistered waste forms.

Marra, S.L.

1999-10-22

167

Glass Ceramic Formulation Data Package  

SciTech Connect

A glass ceramic waste form is being developed for treatment of secondary waste streams generated by aqueous reprocessing of commercial used nuclear fuel (Crum et al. 2012b). The waste stream contains a mixture of transition metals, alkali, alkaline earths, and lanthanides, several of which exceed the solubility limits of a single phase borosilicate glass (Crum et al. 2009; Caurant et al. 2007). A multi-phase glass ceramic waste form allows incorporation of insoluble components of the waste by designed crystallization into durable heat tolerant phases. The glass ceramic formulation and processing targets the formation of the following three stable crystalline phases: (1) powellite (XMoO4) where X can be (Ca, Sr, Ba, and/or Ln), (2) oxyapatite Yx,Z(10-x)Si6O26 where Y is alkaline earth, Z is Ln, and (3) lanthanide borosilicate (Ln5BSi2O13). These three phases incorporate the waste components that are above the solubility limit of a single-phase borosilicate glass. The glass ceramic is designed to be a single phase melt, just like a borosilicate glass, and then crystallize upon slow cooling to form the targeted phases. The slow cooling schedule is based on the centerline cooling profile of a 2 foot diameter canister such as the Hanford High-Level Waste canister. Up to this point, crucible testing has been used for glass ceramic development, with cold crucible induction melter (CCIM) targeted as the ultimate processing technology for the waste form. Idaho National Laboratory (INL) will conduct a scaled CCIM test in FY2012 with a glass ceramic to demonstrate the processing behavior. This Data Package documents the laboratory studies of the glass ceramic composition to support the CCIM test. Pacific Northwest National Laboratory (PNNL) measured melt viscosity, electrical conductivity, and crystallization behavior upon cooling to identify a processing window (temperature range) for melter operation and cooling profiles necessary to crystallize the targeted phases in the waste form.

Crum, Jarrod V.; Rodriguez, Carmen P.; McCloy, John S.; Vienna, John D.; Chung, Chul-Woo

2012-06-17

168

Prediction of glass durability as a function of glass composition and test conditions: Thermodynamics and kinetics  

SciTech Connect

The long-term durability of nuclear waste glasses can be predicted by comparing their performance to natural and ancient glasses. Glass durability is a function of the kinetic and thermodynamic stability of glass in solution. The relationship between the kinetic and thermodynamic aspects of glass durability can be understood when the relative contributions of glass composition and imposed test conditions are delineated. Glass durability has been shown to be a function of the thermodynamic hydration free energy which can be calculated from the glass composition. Hydration thermodynamics also furnishes a quantitative frame of reference to understand how various test parameters affect glass durability. Linear relationships have been determined between the logarithmic extent of hydration and the calculated hydration free energy for several different test geometries. Different test conditions result in different kinetic reactivity parameters such as the exposed glass surface area (SA), the leachant solution volume (V), and the length of time that the glass is in the leachant (t). Leachate concentrations are known to be a function of the kinetic test parameter (SAV)t. The relative durabilities of glasses, including pure silica, obsidians, nuclear waste glasses, medieval window glasses, and frit glasses define a plane in three dimensional ..delta..G/sub hyd/-concentration-(SAV)t space. At constant kinetic conditions, e.g., test geometry and test duration, the three dimensional plane is intersected at constant (SAV)t and the ..delta..G/sub hyd/-concentration plots have similar slopes. The slope represents the natural logarithm of the theoretical slope, (12.303 RT), for the rate of glass dissolution. 53 refs., 4 figs.

Jantzen, C.M.

1988-01-01

169

Surface reactions of natural glasses  

SciTech Connect

Reactions at natural glass surfaces are important in studies involving nuclear waste transport due to chemical control on ground water in host rocks such as basalt and tuff, to potential diffusion into natural hydrated glass surfaces and as natural analogs for waste glass stability. Dissolution kinetics can be described by linear surface reaction coupled with cation interdiffusion with resulting rates similar to those of synthetic silicate glasses. Rates of Cs diffusion into hydrated obsidian surfaces between 25{sup 0} and 75{sup 0}C were determined by XPS depth profiles and loss rates from aqueous solutions. Calculated diffusion coefficients were ten others of magnitude more rapid than predicted from an Arrhenius extrapolation of high temperature tracer diffusion data due to surface hydration reactions.

White, A.F.

1986-12-31

170

Pinhole Glasses  

NASA Astrophysics Data System (ADS)

Eye aberrations are commonly corrected by lenses that restore vision by altering rays before they pass through the cornea. Some modern promoters claim that pinhole glasses are better than conventional lenses in correcting all kinds of refractive defects such as myopia (nearsighted), hyperopia (farsighted), astigmatisms, and presbyopia. Do pinhole glasses really give better vision? Some ways to use this question for motivation in teaching optics have been discussed. For this column we include a series of experiments that students can complete using a model of the eye and demonstrate issues related to pinhole vision correction.

Colicchia, Giuseppe; Hopf, Martin; Wiesner, Hartmut; Zollman, Dean

2008-01-01

171

Effects of glass composition on the liquidus surfaces of high zirconia containing waste glasses  

NASA Astrophysics Data System (ADS)

Waste glasses must meet a variety of requirements for processing and product performance. Processing property constraints such as liquidus temperature (TL) and viscosity, and the product performance constraints such as durability have to be considered when formulating glass for waste immobilization. In this study, TL, glass transition temperature (Tg, and chemical durability of borosilicate waste glasses containing ZrO 2 concentrations from 6--12 mole% were determined. The concentrations of SiO2, ZrO2, Al2O3, B2 O3, Li2O, Na2O, and CaO were varied using a modified extreme vertices approach. Fifty-three statistically designed glasses were hatched and fabricated. Of the 53 glasses, 19 were not fully characterized due to the presence of undissolved solids (i.e., inhomogeneous glass) although extremely high melt temperatures were utilized (>1500°C). Liquidus temperature, glass transition temperature, and durability of the remaining glasses were examined. Liquidus temperatures (TL) were measured using a series of isothermal heat treatments to narrow the TL to within +/-10°C. The primary crystalline phases were identified using optical microscopy and XRD. The three primary phase fields of Parakeldyshite (Na 2ZrSi2O7) Zircon (ZrSiO4), and Baddeleyite (ZrO2) were encountered for the glass composition region evaluated. Glasses with Parakeldyshite as a primary phase were found to have lower liquidus temperatures, than those glasses having, Zircon or Baddeleyite as the primary phase field. Glass transition temperatures and crystallization temperature were determined using DTA. Glass transition temperatures of glass compositions containing higher percentages of alkali were often lower than those with lower percentages of alkali. This is primary due to a reduction in the connectivity of the glass network. Chemical durability was determined using the Product Consistency Test. The most durable glasses were glasses with lower Na2O content and contained both Al2O3 and CaO. This study showed that the effects of oxide components on glass properties were extremely important for selecting a glass formulation with maximum waste loading. The principles of glass structure such as bridging and nonbridging oxygens and polarizability concept were used to understand the effects. Empirical models were developed based on measured data which related liquidus temperature, glass transition temperature, and durability to glass composition. The experimental data was compared to the predicted data of the model. The purpose of these models were to assist in selecting glasses that offer a maximum ZrO2 waste loading for nuclear waste glasses.

Jiemsirilers, Sirithan Bulpakdi

172

Hot isostatically-pressed aluminosilicate glass-ceramic with natural crystalline analogues for immobilizing the calcined high-level nuclear waste at the Idaho Chemical Processing Plant  

SciTech Connect

The additives Si, Al, MgO, P{sub 2}O{sub 5} were mechanically blended with fluorinelsodium calcine in varying proportions. The batches were vacuum sealed in stainless steel canisters and hot isostatically pressed at 20,000 PSI and 1000 C for 4 hours. The resulting suite of glass-ceramic waste forms parallels the natural rocks in microstructural and compositional heterogeneity. Several crystalline phases ar analogous in composition and structure to naturally occurring minerals. Additional crystalline phases are zirconia and Ca-Mg borate. The glasses are enriched in silica and alumina. Approximately 7% calcine elements occur dissolved in this glass and the total glass content in the waste forms averages 20 wt%. The remainder of the calcine elements are partitioned into crystalline phases at 75 wt% calcine waste loading. The waste forms were tested for chemical durability in accordance with the MCC1-test procedure. The leach rates are a function of the relative proportions of additives and calcine, which in turn influence the composition and abundances of the glass and crystalline phases. The DOE leach rate criterion of less than 1 g/m{sup 2}-day is met by all the elements B, Cs and Na are increased by lowering the melt viscosity. This is related to increased crystallization or devitrification with increases in MgO addition. This exploratory work has shown that the increases in waste loading occur by preferred partitioning of the calcine components among crystalline and glass phases. The determination of optimum processing parameters in the form of additive concentration levels, homogeneous blending among the components, and pressure-temperature stabilities of phases must be continued to eliminate undesirable effects of chemical composition, microstructure and glass devitrification.

Raman, S.

1993-12-01

173

Metallic Glasses  

Microsoft Academic Search

The novel internal structures of metallic glasses lead to exceptional strength, corrosion resistance, and ease of magnetization. Combined with low manufacturing costs, these properties make glassy ribbons attractive for many applications. These materials also have scientific fascination because their compositions, structures, and properties have unexpected features.

John J. Gilman

1980-01-01

174

Structure of rhenium-containing sodium borosilicate glass  

SciTech Connect

A series of sodium borosilicate glasses were synthesized with increasing fractions of KReO4 or Re2O7, to 10000 ppm (1 mass%) target Re in glass, to assess the effects of large concentrations of rhenium on glass structure and to estimate the solubility of technetium, a radioactive component in typical low active waste nuclear waste glasses. Magic angle spinning nuclear magnetic resonance (MAS-NMR), Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy were performed to characterize the glasses as a function of Re source additions. In general, silicon was found coordinated in a mixture of Q2 and Q3 structural units, while Al was 4-coordinated and B was largely 3-coordinate and partially 4-coordinated. The rhenium source did not appear to have significant effects on the glass structure. Thus, at the up to the concentrations that remain in dissolved in glass, ~3000 ppm Re by mass maximum. , the Re appeared to be neither a glass-former nor a strong glass modifier., Rhenium likely exists in isolated ReO4- anions in the interstices of the glass network, as evidenced by the polarized Raman spectrum of the Re glass in the absence of sulfate. Analogous to SO42-¬ in similar glasses, ReO4- is likely a network modifier and forms alkali salt phases on the surface and in the bulk glass above solubility.

Goel, Ashutosh; McCloy, John S.; Windisch, Charles F.; Riley, Brian J.; Schweiger, Michael J.; Rodriguez, Carmen P.; Ferreira, Jose M.

2013-03-01

175

IMPACT STRENGTH OF GLASS AND GLASS CERAMIC  

SciTech Connect

Strength of glass and glass ceramic was measured with a bar impact technique. High-speed movies show regions of tensile and compressive failure. The borosilicate glass had a compressive strength of at least 2.2 GPa, and the glass ceramic at least 4 GPa. However, the BSG was much stronger in tension than GC. In ballistic tests, the BSG was the superior armor.

Bless, S.; Tolman, J. [Institute for Advanced Technology, University of Texas at Austin, Austin, TX 78759 (United States)

2009-12-28

176

Gaseous Sulfate Solubility in Glass: Experimental Method  

SciTech Connect

Sulfate solubility in glass is a key parameter in many commercial glasses and nuclear waste glasses. This report summarizes key publications specific to sulfate solubility experimental methods and the underlying physical chemistry calculations. The published methods and experimental data are used to verify the calculations in this report and are expanded to a range of current technical interest. The calculations and experimental methods described in this report will guide several experiments on sulfate solubility and saturation for the Hanford Waste Treatment Plant Enhanced Waste Glass Models effort. There are several tables of sulfate gas equilibrium values at high temperature to guide experimental gas mixing and to achieve desired SO3 levels. This report also describes the necessary equipment and best practices to perform sulfate saturation experiments for molten glasses. Results and findings will be published when experimental work is finished and this report is validated from the data obtained.

Bliss, Mary

2013-11-30

177

Analytical electron microscopy study of surface layers formed on the french SON68 nuclear waste glass during vapor hydration at 200{degree}C.  

SciTech Connect

Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six SON68 (inactive R7T7) waste glasses which were altered in the presence of saturated water vapor (200{sup o}C) for 22, 91, 241, 908, 1000, 1013, and 1021 days. The samples were examined by AEM in cross-section (lattice-fringe imaging, micro-diffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered by a thin altered rind, and the surface layer thickness increased with increasing time of reaction, ranging from 0.5 to 30 {mu}m in thickness. Six distinctive zones, based on phase chemistry and microstructure, were distinguished within the well-developed surface layers. Numerous crystalline phases such as analcime, gyrolite, tobermorite, apatite, and weeksite were identified on the surfaces of the reacted glasses as precipitates. The majority of the surface layer volume was composed of two basic structures that are morphologically and chemically distinct: The A-domain consisted of well-crystallized fibrous smectite aggregates; and the B-domain consisted of poorly-crystallized regions containing smectite, possibly montmorillonite, crystallites and a ZrO{sub 2}-rich amorphous silica matrix. The retention of the rare-earth elements, Mo, and Zr mostly occurred within the B-domain; while transition metal elements, such as Zn, Cr, Ni, Mn, and Fe, were retained in the A-domain. The element partitioning among A-domains and B-domains and recrystallization of the earlier-formed B-domains into the A-domain smectites were the basic processes which have controlled the chemical and structural evolution of the surface layer. The mechanism of surface layer formation during vapor hydration are discussed based on these cross-sectional AEM results.

Gong, W. L.; Wang, L. M.; Ewing, R. C.; Vernaz, E.; Bates, J. K.; Ebert, W. L.; Chemical Engineering; Univ. of New Mexico; CEA-VALRHO

1998-04-01

178

Analytical electron microscopy study of surface layers formed on the French SON68 nuclear waste glass during vapor hydration at 200°C  

NASA Astrophysics Data System (ADS)

Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six SON68 (inactive R7T7) waste glasses which were altered in the presence of saturated water vapor (200°C) for 22, 91, 241, 908, 1000, 1013, and 1021 days. The samples were examined by AEM in cross-section (lattice-fringe imaging, micro-diffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered by a thin altered rind, and the surface layer thickness increased with increasing time of reaction, ranging from 0.5 to 30 ?m in thickness. Six distinctive zones, based on phase chemistry and microstructure, were distinguished within the well-developed surface layers. Numerous crystalline phases such as analcime, gyrolite, tobermorite, apatite, and weeksite were identified on the surfaces of the reacted glasses as precipitates. The majority of the surface layer volume was composed of two basic structures that are morphologically and chemically distinct: The A-domain consisted of well-crystallized fibrous smectite aggregates; and the B-domain consisted of poorly-crystallized regions containing smectite, possibly montmorillonite, crystallites and a ZrO 2-rich amorphous silica matrix. The retention of the rare-earth elements, Mo, and Zr mostly occurred within the B-domain; while transition metal elements, such as Zn, Cr, Ni, Mn, and Fe, were retained in the A-domain. The element partitioning among A-domains and B-domains and recrystallization of the earlier-formed B-domains into the A-domain smectites were the basic processes which have controlled the chemical and structural evolution of the surface layer. The mechanism of surface layer formation during vapor hydration are discussed based on these cross-sectional AEM results.

Gong, W. L.; Wang, L. M.; Ewing, R. C.; Vernaz, E.; Bates, J. K.; Ebert, W. L.

1998-04-01

179

Electron Spin Resonance Study of Fe3+ and Mn2+ Ions in 17-Year-Old Nuclear-Waste-Glass Simulants Containing PuO2 with Different Degrees of 238Pu Substitution  

SciTech Connect

Three samples of a model nuclear waste glass, DRG-P1, P2, and P3, were prepared at PNNL in 1982 with identical chemical compositions but were respectively batched with 0.0, 0.1, and 0.9 wt% of 238PuO2 (half life 87.8 years) partially replacing the 1.0 wt% 239PuO2 present in DRG-P1. In 1999, samples of these glasses were sent to the Naval Research Laboratory for electron spin resonance (ESR) measurements. No radiation-induced point defects were observed. Profound alpha decay-induced changes in the ESR spectra of the batched iron-group ions were found. The spectra recorded for DRG-P1 were shown by absolute spin counts to have ESR intensities equivalent to ~85% of the sum of the batched 8.28 mole% Fe3+ and 2.79 mole% Mn2+, assuming all of those ions to behave as paramagnetic S=5/2 states at room temperature. Separate experiments and calculations ruled out the possibility of precipitated magnetite-like precipitates comprising even so much as 0.01% of the total iron. A relatively weak ESR spectral feature observed at g=4.3 is the known signature of dilute Fe3+ in glasses. However, the strongest ESR signal was found to be characterized by a first-derivative zero crossing at g=2.06 and a peak-to-peak derivative linewidth of ~150 mT, which is virtually invariant in shape with both measurement temperature and alpha-decay dose. It was discovered that these broad line shapes could be accurately simulated as weighted sums of Lorentzian shape functions of differing widths but having the same g value. The absence of any measurable anisotropy in the broad line, coupled with the temperature invariance of its width, imply the existence of extremely strong exchange interactions within clusters of Fe3+, Fe2+, Mn2+, and Ni2+ ions characterized by extremely short-range magnetic order. The result is a speromagnetic system rather than exhibiting a distinct Néel temperature. The most evident ESR effect of 17 years of 238Pu decay is the (irreversible) lowering of the intensity of the "broad line" in rough proportion to the amount of 238Pu in the sample, with concomitant increases in the amplitude of the g=4.3 feature. It was additionally observed that cooling these glasses to successively lower temperatures gives rise to reversible lowering of the broad-line intensity and increasing of the strength of the g=4.3 feature when compared with theoretical expectation for non-interacting paramagnets. The truly remarkable observation that the broad lines could be simulated as weighted sums of pure Lorentzian functions of differing widths fortuitously opened the way for high precision measurements of the ESR intensities of experimental spectra that are far broader than the magnetic field range of the available laboratory electromagnets. The areas under the simulated absorption curves fitted to the experimental spectra in the manner described provided an empirical measure of the degrees to which the present model nuclear waste glasses had been affected by alpha-decay self irradiation. Specifically, the broad-line ESR integrated-intensity data as a function of 238Pu alphadecay dose (proportional to the 238Pu doping level in these fixed-time experiments) proved to be accurately fitted by a simple saturating exponential function asymptotic to zero for infinite-time self irradiation. This result promises a precise means of extrapolating thousands of years into the future the process of "super-vitrification" that results from the creation and rapid quenching of thermal spikes due to alpha decay in glasses immobilizing 239Pu and other actinide elements. In addition, because the ESR spectra of several very different candidate high-level nuclear waste (HLW) glass compositions containing even higher amounts of Fe2O3 are also shown here to be decomposable into sums of pure Lorentzians, the analytical method we describe should be applicable to these and many other HLW glasses containing both iron-group oxides and radionuclides.

Griscom, David L.; Weber, William J.

2011-03-01

180

A simple method for tuning the glass transition process in inorganic phosphate glasses  

PubMed Central

The physical modification of glass transition temperature (Tg) and properties of materials via blending is a common practice in industry and academia and has a large economic advantage. In this context, simple production of hitherto unattainable new inorganic glass blends from already existing glass compositions via blending raises much hope with the potential to provide new glasses with new and improved properties, that cannot be achieved with classical glass synthesis, for a plethora of applications such as computers screens, glass-to-metal seals, and storage materials for nuclear wastes. Here, we demonstrate that blends of the specific glass compositions studied are miscible in all proportions, an unreported phenomenon in hard condensed matter like glass. Interestingly, excellent agreement was found between the obtained data and calculated Tgs from theoretical equations (Supplementary information) for predicting the composition dependence of Tg for miscible blends with weak but significant specific interactions between the blend components. That this blending method is at present not applied to inorganic glasses reflects the fact that water and chemically resistant phosphate glasses with relatively low Tgs have become available only recently. PMID:25666949

Fulchiron, René; Belyamani, Imane; Otaigbe, Joshua U.; Bounor-Legaré, Véronique

2015-01-01

181

A simple method for tuning the glass transition process in inorganic phosphate glasses.  

PubMed

The physical modification of glass transition temperature (Tg) and properties of materials via blending is a common practice in industry and academia and has a large economic advantage. In this context, simple production of hitherto unattainable new inorganic glass blends from already existing glass compositions via blending raises much hope with the potential to provide new glasses with new and improved properties, that cannot be achieved with classical glass synthesis, for a plethora of applications such as computers screens, glass-to-metal seals, and storage materials for nuclear wastes. Here, we demonstrate that blends of the specific glass compositions studied are miscible in all proportions, an unreported phenomenon in hard condensed matter like glass. Interestingly, excellent agreement was found between the obtained data and calculated Tgs from theoretical equations (Supplementary information) for predicting the composition dependence of Tg for miscible blends with weak but significant specific interactions between the blend components. That this blending method is at present not applied to inorganic glasses reflects the fact that water and chemically resistant phosphate glasses with relatively low Tgs have become available only recently. PMID:25666949

Fulchiron, René; Belyamani, Imane; Otaigbe, Joshua U; Bounor-Legaré, Véronique

2015-01-01

182

Ultrastable metallic glass.  

PubMed

A new metallic glass, which was created by vapour deposition at an appropriately high substrate temperature, shows exceptional thermal stability, and enhanced glass transition temperature and elastic modulus. Comparing this new material with other organic glasses prepared by similar routes and known as ultrastable glasses demonstrates the formation of ultrastable glassy materials correlates to the important concept of fragility. PMID:23956053

Yu, Hai-Bin; Luo, Yuansu; Samwer, Konrad

2013-11-01

183

Nanocrystallization of metallic glasses  

Microsoft Academic Search

The paper summarizes briefly the current status of research in the field of nanocrystallization of metallic glasses especially highlighting the influence of glass composition and conditions of devitrification process on size, morphology and composition of crystallization products. Conventional crystallization creates a nanocrystalline structure only in glasses with particular compositions. Any metallic glass, decomposing in a primary crystallization process, can be

Tadeusz Kulik

2001-01-01

184

DEVELOPMENT OF GLASS MATRICES FOR HLW RADIOACTIVE WASTES  

SciTech Connect

Vitrification is currently the most widely used technology for the treatment of high level radioactive wastes (HLW) throughout the world. Most of the nations that have generated HLW are immobilizing in either borosilicate glass or phosphate glass. One of the primary reasons that glass has become the most widely used immobilization media is the relative simplicity of the vitrification process, e.g. melt waste plus glass forming frit additives and cast. A second reason that glass has become widely used for HLW is that the short range order (SRO) and medium range order (MRO) found in glass atomistically bonds the radionuclides and governs the melt properties such as viscosity, resistivity, sulphate solubility. The molecular structure of glass controls contaminant/radionuclide release by establishing the distribution of ion exchange sites, hydrolysis sites, and the access of water to those sites. The molecular structure is flexible and hence accounts for the flexibility of glass formulations to waste variability. Nuclear waste glasses melt between 1050-1150 C which minimizes the volatility of radioactive components such as Tc{sup 99}, Cs{sup 137}, and I{sup 129}. Nuclear waste glasses have good long term stability including irradiation resistance. Process control models based on the molecular structure of glass have been mechanistically derived and have been demonstrated to be accurate enough to control the world's largest HLW Joule heated ceramic melter in the US since 1996 at 95% confidence.

Jantzen, C.

2010-03-18

185

Laboratory work in support of West Valley glass development  

SciTech Connect

Over the past six years, Pacific Northwest Laboratory (PNL) has conducted several studies in support of waste glass composition development and testing of glass compositions suitable for immobilizing the nuclear wastes stored at West Valley, New York. As a result of pilot-scale testing conducted by PNL, the glass composition was changed from that originally recommended in response to changes in the waste stream, and several processing-related problems were discovered. These problems were solved, or sufficiently addressed to determine their likely effect on the glass melting operations to be conducted at West Valley. This report describes the development of the waste glass composition, WV-205, and discusses solutions to processing problems such as foaming and insoluble sludges, as well as other issues such as effects of feed variations on processing of the resulting glass. An evaluation of the WV-205 glass from a repository perspective is included in the appendix to this report.

Bunnell, L.R.

1988-05-01

186

Glasses in the D'Orbigny angrite  

NASA Astrophysics Data System (ADS)

The angrites are a small and heterogeneous group of achondritic meteorites with highly unusual chemical and mineralogical features. The abundant presence of glasses in D'Orbigny makes this rock a unique member of the angrite group. Glasses fill open spaces, form pockets, and occur as inclusions in olivines. Their physical settings exclude an incorporation from an external source. Major and trace element (rare earth elements [REE], Li, B, Be, transition elements, N and C) contents of these glasses and host olivines were measured combining laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), secondary-ion mass spectrometry (SIMS), Nuclear Reaction Analysis (NRA), and EMP techniques. Based on the major element composition, glasses filling voids could represent either a melt formed by melting an angritic rock or a melt from which angrites could have crystallized. Trace element contents of these glasses strongly indicate a direct link to the D'Orbigny bulk meteorite. They are incompatible with the formation of the glasses by partial melting of a chondritic source rock or by shock melting. The refractory elements (e.g., Al, Ti, Ca) have about 10 × CI abundances with CaO/TiO 2 and FeO/MnO ratios being approximately chondritic. Trace element abundances in the glasses appear to be governed by volatility and suggest that the refractory elements in the source had chondritic relative abundances. Although the glasses (and the whole rock) lack volatile elements such as Na and K, they are rich in some moderately volatile elements such as B, V, Mn, Fe (all with close to CI abundances), and Li (about 3-5 × CI). These elements likely were added to the glass in a sub-solidus metasomatic elemental exchange event. We have identified a novel mechanism for alteration of glass and rock compositions based on an exchange of Al and Sc for Fe and other moderately volatile elements in addition to the well-known metasomatic exchange reactions (e.g., Ca-Na and Mg-Fe). Because glass inclusions in olivine were partly shielded from the metasomatic events by the host crystal, their chemical composition is believed to be closer to the original composition than that of any other glasses. The relative trace element abundances in glasses of glass inclusions in olivine and glass pockets are also unfractionated and at the 10 to 20 × CI level. These glasses are chemically similar to the common void-filling glasses but show a much wider compositional variation. Inclusion glasses demonstrate that at least olivine grew with the help of a liquid. In analogy to olivines in carbonaceous chondrites, initial formation could also have been a vapor-liquid-solid condensation process. At that time, the glass had a purely refractory composition. This composition, however, was severely altered by the metasomatic addition of large amounts of FeO and other moderately volatile elements. The presence of volatile elements such as carbon and nitrogen in glasses of glass inclusions is another feature that appears to give these glasses a link with those hosted by olivines of carbonaceous chondrites. All these features point to an origin from a vapor with relative abundances of condensable elements similar to those in the solar nebula.

Varela, Maria Eugenia; Kurat, Gero; Zinner, Ernst; Métrich, Nicole; Brandstätter, Franz; Ntaflos, Theodoros; Sylvester, Paul

2003-12-01

187

Photoluminescence in glasses and glass ceramics  

NASA Astrophysics Data System (ADS)

Photoluminescence in the UV-VIS region is a very sensitive analytical method and also an important optical property of glasses and glass ceramics for different applications which depends strongly on active centers, surrounding host glass composition and their interactions. Fluoride, phosphate, and silicate glasses of high intrinsic UV transmission and high purity doped with active luminescent ions of different electronic configurations (s2: As3+, Sb3+, Sn2+, Pb2+; d0: Ti4+, Nb+, Mo6+, Ta5+, W6; d10: Zn2+, Ag+ and Cu+, d5: Mn2+, fn like Sm3+, Eu3+, Eu2+, Tb3+) were investigated. Some glasses were transformed in glass ceramics. Distribution of coordination and change in the case of Zn2+ and Mn2+ were detected. Mn2+ can substitute Zn2+ in glass and also in crystal phases, Zn2SiO4 (willemite) and ZnAl2O4 (gahnite). But the larger RE ions cannot do it. So, the luminescence can be increased or decreased by the transformation of glasses in glass ceramics. Blue, green and red photoluminescence emission with various lifetimes, ?e ~ 1 ?s to 25 ms, were registered.

Ehrt, Doris

2009-07-01

188

Reaction cured glass and glass coatings  

NASA Technical Reports Server (NTRS)

The invention relates to reaction cured glass and glass coatings prepared by reacting a compound selected from the group consisting of silicon tetraboride, silicon hexaboride, other boron silicides, boron and mixtures with a reactive glass frit composed of a porous high silica borosilicate glass and boron oxide. The glassy composites of the present invention are useful as coatings on low density fibrous porous silica insulations used as heat shields and for articles such as reaction vessels that are subjected to high temperatures with rapid heating and cooling and that require resistance to temperature and repeated thermal shock at temperatures up to about 1482C (2700PF).

Goldstein, H. E.; Leiser, D. B.; Katvala, V. W. (inventors)

1978-01-01

189

Retention of Halogens in Waste Glass  

SciTech Connect

In spite of their potential roles as melting rate accelerators and foam breakers, halogens are generally viewed as troublesome components for glass processing. Of five halogens, F, Cl, Br, I, and At, all but At may occur in nuclear waste. A nuclear waste feed may contain up to 10 g of F, 4 g of Cl, and ?100 mg of Br and I per kg of glass. The main concern is halogen volatility, producing hazardous fumes and particulates, and the radioactive iodine 129 isotope of 1.7x10^7-year half life. Because F and Cl are soluble in oxide glasses and tend to precipitate on cooling, they can be retained in the waste glass in the form of dissolved constituents or as dispersed crystalline inclusions. This report compiles known halogen-retention data in both high-level waste (HLW) and low-activity waste (LAW) glasses. Because of its radioactivity, the main focus is on I. Available data on F and Cl were compiled for comparison. Though Br is present in nuclear wastes, it is usually ignored; no data on Br retention were found.

Hrma, Pavel R.

2010-05-01

190

WASTE GLASS MELTER PROCESS MONITORING WITH MILLIMETER WAVES  

EPA Science Inventory

Millimeter-wave technologies can provide novel and reliable online monitoring capability for many important parameters inside nuclear waste glass melters, including temperature, emissivity, density, and viscosity. The physical and analytical basis for millimeter-wave monitoring o...

191

Oxynitride glass fibers  

NASA Technical Reports Server (NTRS)

Research at the Army Materials Technology Laboratory (AMTL) and elsewhere has shown that many glass properties including elastic modulus, hardness, and corrosion resistance are improved markedly by the substitution of nitrogen for oxygen in the glass structure. Oxynitride glasses, therefore, offer exciting opportunities for making high modulus, high strength fibers. Processes for making oxynitride glasses and fibers of glass compositions similar to commercial oxide glasses, but with considerable enhanced properties, are discussed. We have made glasses with elastic moduli as high as 140 GPa and fibers with moduli of 120 GPa and tensile strengths up to 2900 MPa. AMTL holds a U.S. patent on oxynitride glass fibers, and this presentation discusses a unique process for drawing small diameter oxynitride glass fibers at high drawing rates. Fibers are drawn through a nozzle from molten glass in a molybdenum crucible at 1550 C. The crucible is situated in a furnace chamber in flowing nitrogen, and the fiber is wound in air outside of the chamber, making the process straightforward and commercially feasible. Strengths were considerably improved by improving glass quality to minimize internal defects. Though the fiber strengths were comparable with oxide fibers, work is currently in progress to further improve the elastic modulus and strength of fibers. The high elastic modulus of oxynitride glasses indicate their potential for making fibers with tensile strengths surpassing any oxide glass fibers, and we hope to realize that potential in the near future.

Patel, Parimal J.; Messier, Donald R.; Rich, R. E.

1991-01-01

192

Room temperature corrosion of museum glass: an investigation using low-energy SIMS  

NASA Astrophysics Data System (ADS)

Glass is often regarded as a stable durable material and the wide range of contemporary applications of glass reinforces this belief. There is nothing inherent in the glassy state, however, that confers stability, and the problem of glass corrosion has been well documented since the 17th century. Glass corrosion still affects commercial float glass production and glasses used to contain high level nuclear waste, but one area in particular where glass corrosion is very common is in the museum environment. In order to conserve these artefacts it is essential to understand fully both the composition of the corroded glass and the corrosion mechanism. In this study, the application of low-energy SIMS for the depth profiling of corroded glass is studied with the aim of finding a suitable environment for the safe storage of glass objects in a museum.

Fearn, Sarah; McPhail, David S.; Oakley, Victoria

2004-06-01

193

Alice through Looking Glass after Looking Glass  

E-print Network

Alice through Looking Glass after Looking Glass: The Mathematics of Mirrors and Kaleidoscopes Roe back in time for tea. #12;Alice's Kaleidoscope Problem: · Kaleidoscope: Arrangement of n mirrors (hyperplanes through 0) in n-dimensional Euclidean space · Kaleidoscope Condition: Multiple reflections

Goodman, Roe

194

FOAM GLASS INSULATION FROM WASTE GLASS  

EPA Science Inventory

Waste glass has proven to be effective for the production of foam glass insulation both in the bulk or rigid board form and pellet form. Problems inherent with the use of water, carbon black and calcium carbonate as the foaming agents, have been identified and many have been solv...

195

High-Temperature Studies of Glass Dissolution Rates Close to Saturation  

SciTech Connect

Most long-lived radionuclides associated with an underground nuclear test are incorporated into a melt glass and are released by glass dissolution to become part of the hydrologic source term (HST) (Pawloski et al., 2001). Although the rates of rhyolite glass dissolution are well known under conditions where the fluid is far from saturation with respect to glass, the rates are not well known under conditions where the fluid approaches saturation. These rates are commonly much lower than the far-fromsaturation rates, often by a factor greater than 100. In recent HST simulations (Pawloski et al., 2001; Pawloski et al., 2000; Tompson et al., 1999), we conservatively estimated steady-state release rates based on a far-from-saturation fluid conditions. In recent CHESHIRE near-field simulations (Pawloski et al., 2001), it was predicted that {approx}30% of the nuclear melt glass dissolved over 1000 years. Although the ''far-from-saturation rate'' approach provides a conservative estimate of glass dissolution, it may greatly overestimate the rates of melt glass dissolution. At CHESHIRE, less conservative estimates suggest that only {approx}1% of the nuclear melt glass will dissolve in 1000 years. Lower glass dissolution rates result in lower radionuclide release rates from nuclear melt glass. The following report documents glass dissolution experiments performed to measure glass dissolution rates close to saturation.

Zavarin, M; Roberts, S; Zhao, P; Williams, R; Rose, T; Rainer, A; Pawloski, G

2004-06-14

196

Glass in Class  

ERIC Educational Resources Information Center

Glass is reviewed from fabrication to application, laying emphasis on the wide-ranging physics involved. This begins with liquids and solids and the way in which glasses are defined and can be demonstrated in the classroom. At the atomic level the regular structure of crystals and their irregular counterparts in glasses are explained through…

Greaves, Neville

2005-01-01

197

Nanocrystalline glass ceramics: Structural, physical and optical properties  

NASA Astrophysics Data System (ADS)

Four different transition metals contained nanocrystalline glass ceramics are synthesized by melting and quenching technique. The transition metal oxides play as former, modifier or both the roles depending on their oxidation states, field strength and covalent characteristics. The optical band gaps are observed in the range of 3.2-5.5 eV. The presence of nano-crystalline phases dominates the optical band gap. The softening temperature (Ts) is mainly affected by the residual glass in glass ceramics. These glass ceramics can be used as shielding materials for nuclear waste.

Singh, Satwinder; Singh, K.

2015-02-01

198

Radiation coloration resistant glass  

DOEpatents

A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10.sup.7 rad, the coloration resistant glass does not lose transparency.

Tomozawa, Minoru (Troy, NY); Watson, E. Bruce (Troy, NY); Acocella, John (Troy, NY)

1986-01-01

199

Radiation coloration resistant glass  

DOEpatents

A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10[sup 7] rad, the coloration resistant glass does not lose transparency. 3 figs.

Tomozawa, M.; Watson, E.B.; Acocella, J.

1986-11-04

200

Application of the hydration thermodynamic model for glass durability under saturated tuff repository conditions  

SciTech Connect

The effects of tuff repository groundwater on glass dissolution and surface layer formation was examined utilizing the hydration thermodynamic model. A 28 day MCC-1 monolithic durability test was performed on the following glasses: SiO{sub 2}, obsidian, basalt, medieval window glasses, frit glass, and simulated nuclear waste glass. Silica dissolution was compared with the pH corrected free energy of hydration and shown to have the theoretical slope, ln(1/2.303RT), in agreement with MCC-1 tests using deionized water. X-ray diffraction and scanning electron microscopy identified clays of the saponite family and carbonates, on the glass surfaces leached in tuff groundwater. 31 refs.

Ramsey, W.G. [Clemson Univ., SC (USA); Jantzen, C.M. [Westinghouse Savannah River Co., Aiken, SC (USA)

1990-12-31

201

Acoustics of glass harmonicas  

NASA Astrophysics Data System (ADS)

Glass musical instruments are probably as old as glassmaking. At least as early as the 17th century it was discovered that wine glasses, when rubbed with a wet finger, produced a musical tone. A collection of glasses played in this manner is called a glass harp. Another type of glass harmonica, called the armonica by its inventor Benjamin Franklin, employs glass bowls or cups turned by a horizontal axle, so the performer need only touch the rim of the bowls as they rotate to set them into vibration. We discuss the modes of vibration of both types of glass harmonica, and describe the different sounds that are emitted by rubbing, tapping, or bowing them. Rubbing with a wet finger tends to excite only the (2,0) mode and its harmonics through a ``stick-slip'' process, while tapping excites the other modes as well.

Rossing, Thomas D.

2001-05-01

202

Scanning Auger microscopy study of lanthanum partitioning in sphene-based glass?ceramics  

Microsoft Academic Search

Glass-ceramics are being investigated as possible hosts for the radioactive wastes that would result from recycling irradiated nuclear fuels. For a glass?ceramic to be a superior waste form to a single-phase glass, some of the long-lived actinides and fission products must be preferentially incorporated into the lattice of the crystalline phase. The partitioning of lanthanum in sphene-based glass?ceramics has been

W. H. Hocking; P. J. Haywaed; D. G. Watson; G. C. Allen

1984-01-01

203

Random pinning glass model  

PubMed Central

Glass transition, in which viscosity of liquids increases dramatically upon decrease of temperature without any major change in structural properties, remains one of the most challenging problems in condensed matter physics despite tremendous research efforts in past decades. On the other hand, disordered freezing of spins in magnetic materials with decreasing temperature, the so-called “spin glass transition,” is understood relatively better. A previously found similarity between some spin glass models and the structural glasses inspired development of theories of structural glasses based on the scenario of spin glass transition. This scenario, although it looks very appealing, is still far from being well established. One of the main differences between standard spin systems and molecular systems is the absence of quenched disorder and the presence of translational invariance: it often is assumed that this difference is not relevant, but this conjecture still needs to be established. The quantities, which are well-defined and characterized for spin models, are not easily calculable for molecular glasses because of the lack of quenched disorder that breaks the translational invariance in the system. Thus the characterization of the similarity between spin and the structural glass transition remains an elusive subject. In this study, we introduced a model structural glass with built-in quenched disorder that alleviates this main difference between the spin and molecular glasses, thereby helping us compare these two systems: the possibility of producing a good thermalization at rather low temperatures is one of the advantages of this model. PMID:23382186

Karmakar, Smarajit; Parisi, Giorgio

2013-01-01

204

Diamond turning of glass  

SciTech Connect

A new research initiative will be undertaken to investigate the critical cutting depth concepts for single point diamond turning of brittle, amorphous materials. Inorganic glasses and a brittle, thermoset polymer (organic glass) are the principal candidate materials. Interrupted cutting tests similar to those done in earlier research are Ge and Si crystals will be made to obtain critical depth values as a function of machining parameters. The results will provide systematic data with which to assess machining performance on glasses and amorphous materials

Blackley, W.S.; Scattergood, R.O.

1988-12-01

205

Helium diffusion in curium-doped borosilicate waste glass  

NASA Astrophysics Data System (ADS)

The isothermal release of helium from 244Cm-doped borosilicate glass has been studied as a function of time at different annealing temperatures. Helium measurements were performed using a micro gas chromatograph coupled to a furnace installed in a hot cell at ATALANTE nuclear research facility. Plane-parallel glass samples were prepared from glass discs that had been stored for 5.1 years at room temperature, accumulating around 10 19 alpha decays per gram of glass, a level that will be reached in current nuclear glass packages several thousand years after disposal. The experimental helium release data were simulated using a 3D numerical model to determine the helium diffusion coefficients. The extracted diffusion coefficients follow the Arrhenius law with an activation energy of 0.61 ± 0.03 eV and a pre-exponential factor of (5.7 ± 1.6) × 10 -3 cm 2 s -1. The results were compared with literature data on damaged and undamaged glasses to assess the effect of glass damage on helium release. The helium release results are consistent with a thermal diffusion mechanism involving only one population of helium atoms. The helium diffusion coefficients were unaffected by the glass alpha damage.

Fares, T.; Peuget, S.; Bouty, O.; Deschanels, X.; Magnin, M.; Jégou, C.

2011-09-01

206

Drugstore Reading Glasses  

NASA Astrophysics Data System (ADS)

The occasion for this paper was my reading of a paper in the February 2005 issue of TPT. As one gets older the near point of the eye begins to recede.2 This is called presbyopia.3 An alternative to purchasing glasses from an optometrist is to purchase an inexpensive pair of reading glasses in a pharmacy. The pharmacy has these glasses ordered by diopters corresponding to the strength of the lens needed for a particular presbyopic eye. The glasses are, of course, not available for myopic eyes.

Erlichson, Herman

2006-03-01

207

Glass--Sand + Imagination  

NASA Astrophysics Data System (ADS)

Glass is older than recorded history, and yet it is as new as tomorrow! How, when, or where man first learned to make glass is not known, but we do know that the ancient Egyptians were making glass articles as early as 2,600 B.C.E. (The making of glass beads may have begun as much as 3000 years earlier.) They used it to make jewelry and luxury items, such as decorative bowls and perfume bottles, available only to the wealthy.

Kolb, Kenneth E.; Kolb, Doris K.

2000-07-01

208

Rare Earth Phosphate Glass and Glass-Ceramic Proton Conductors  

SciTech Connect

The structure and conductivity of cerium and lanthanum phosphate glasses and glass-ceramics were investigated. The effects of varying the metal to phosphate ratio in the glasses, doping LaP3O9 glasses with Ce, and recrystallization of CeP3O9 glasses, on the glasses' microstructure and total conductivity were investigated using XRD, SEM, and AC impedance techniques. Strong increases in conductivity occurred when the glasses were recrystallized: the conductivity of a cerium metaphosphate glass increased conductivity after recrystallization from 10-7.5 S/cm to 10-6 S/cm at 400oC.

De Jonghe, Lutgard C.; Ray, Hannah L.; Wang, Ruigang

2008-12-03

209

Development and characterization of basalt-glass ceramics for the immobilization of transuranic wastes  

SciTech Connect

Basalt-based waste forms were developed for the immobilization of transuranic (TRU) contaminated wastes. The specific waste studied is a 3:1 blend of process sludge and incinerator ash. Various amounts of TRU blended waste were melted with Pomona basalt powder. The vitreous products were subjected to a variety of heat treatment conditions to form glass ceramics. The total crystallinity of the glass ceramic, ranging from 20 to 45 wt %, was moderately dependent on composition and heat treatment conditions. Three parent glasses and four glass ceramics with varied composition and heat treatment were produced for detailed phase characterization and leaching. Both parent glasses and glass ceramics were mainly composed of a continuous, glassy matrix phase. This glass matrix entered into solution during leaching in both types of materials. The Fe-Ti rich dispersed glass phase was not significantly degraded by leaching. The glass ceramics, however, exhibited four to ten times less elemental releases during leaching than the parent glasses. The glass ceramic matrix probably contains higher Fe and Na and lower Ca and Mg relative to the parent glass matrix. The crystallization of augite in the glass ceramics is believed to contribute to the improved leach rates. Leach rates of the basalt glass ceramic are compared to those of other TRU nuclear waste forms containing /sup 239/Pu.

Lokken, R.O.; Chick, L.A.; Thomas, L.E.

1982-09-01

210

Breaking Glass with Sound  

NSDL National Science Digital Library

This video from MIT TechTV demonstrates how to break a glass using sound. The demonstrator determines the resonant frequency of the glass and plays a tone of that frequency with a function generator. The video page has a description of the phenomenon beneath the video.

2009-11-16

211

Disappearing Glass Rods  

NSDL National Science Digital Library

In this optics activity, learners discover how they can make glass objects "disappear." Learners submerge glass objects like stirring rods into a beaker of Wesson™ oil to explore how the principles of reflection and refraction affect what we see. Use this activity as a demonstration or allow learners to experiment on their own.

2011-12-05

212

Stained Glass Glue  

NSDL National Science Digital Library

In this activity on page 6 of the PDF, learners use glue instead of glass to create artwork that can be hung in a window. Discover how the chemicals in various materials mix together to make a colorful, translucent "stained glass" creation.

Society, American C.

2001-01-01

213

Surface Conductive Glass.  

ERIC Educational Resources Information Center

Discusses the properties of surface-conducting glass and the chemical nature of surface-conducting stannic (tin) oxide. Also provides the procedures necessary for the preparation of surface-conducting stannic oxide films on glass substrates. The experiment is suitable for the advanced inorganic chemistry laboratory. (JN)

Tanaka, John; Suib, Steven L.

1984-01-01

214

Glass ionomer restoratives.  

PubMed

This article gives an overview of the new hybrid (light-cured) glass ionomers, which are a combination of auto-cured glass ionomer and light-cured composite resin. The characteristics of these materials and the different brands available are discussed. A clinical technique for restoration of cervical lesions with these materials is presented. PMID:8040719

Berry, E A

1993-01-01

215

Bulk metallic glasses  

Microsoft Academic Search

In the last decade metallic glasses have regained considerable interest due to the fact that new glass-forming compositions have been found that have a critical cooling rate of less than 100 K\\/s and can be made glassy with dimensions of 1 cm or more. The development of such alloys with a very high resistance to crystallization of the undercooled melt

Jörg F. Löffler

2003-01-01

216

Defense HLW Glass Degradation Model  

SciTech Connect

The purpose of this report is to document the development of a model for calculating the release rate for radionuclides and other key elements from high-level radioactive waste (HLW) glasses under exposure conditions relevant to the performance of the repository. Several glass compositions are planned for the repository, some of which have yet to be identified (i.e., glasses from Hanford and Idaho National Engineering and Environmental Laboratory). The mechanism for glass dissolution is the same for these glasses and the glasses yet to be developed for the disposal of DOE wastes. All of these glasses will be of a quality consistent with the glasses used to develop this report.

D. Strachan

2004-10-20

217

Sodium and hydrogen analysis of room temperature glass corrosion using low energy Cs SIMS  

NASA Astrophysics Data System (ADS)

Corrosion affects commercial float glass production and glasses used to contain high level nuclear waste. In order to prevent the corrosion it is necessary to understand the composition of the corroded glass and the corrosion mechanism taking place. SIMS depth profiling lends itself well to monitoring the compositional changes that occur during the corrosion process. However, most studies have analysed glass that has been corroded using accelerated ageing conditions. In this work a soda-lime glass has been aged at room temperature under known atmospheric humidity for increasing periods of time. The aged glass has then been depth profiled using a low energy (1 keV) Cs beam monitoring both the sodium and hydrogen signals concurrently. The depth profiles show that in the region directly below the glass surface that is severely depleted in sodium, there is an increased level of hydrogen compared to the bulk glass indicating an increase in the water content within this region.

Fearn, S.; McPhail, D. S.; Morris, R. J. H.; Dowsett, M. G.

2006-07-01

218

Engineering Glass Passivation Layers -Model Results  

SciTech Connect

The immobilization of radioactive waste into glass waste forms is a baseline process of nuclear waste management not only in the United States, but worldwide. The rate of radionuclide release from these glasses is a critical measure of the quality of the waste form. Over long-term tests and using extrapolations of ancient analogues, it has been shown that well designed glasses exhibit a dissolution rate that quickly decreases to a slow residual rate for the lifetime of the glass. The mechanistic cause of this decreased corrosion rate is a subject of debate, with one of the major theories suggesting that the decrease is caused by the formation of corrosion products in such a manner as to present a diffusion barrier on the surface of the glass. Although there is much evidence of this type of mechanism, there has been no attempt to engineer the effect to maximize the passivating qualities of the corrosion products. This study represents the first attempt to engineer the creation of passivating phases on the surface of glasses. Our approach utilizes interactions between the dissolving glass and elements from the disposal environment to create impermeable capping layers. By drawing from other corrosion studies in areas where passivation layers have been successfully engineered to protect the bulk material, we present here a report on mineral phases that are likely have a morphological tendency to encrust the surface of the glass. Our modeling has focused on using the AFCI glass system in a carbonate, sulfate, and phosphate rich environment. We evaluate the minerals predicted to form to determine the likelihood of the formation of a protective layer on the surface of the glass. We have also modeled individual ions in solutions vs. pH and the addition of aluminum and silicon. These results allow us to understand the pH and ion concentration dependence of mineral formation. We have determined that iron minerals are likely to form a complete incrustation layer and we plan to look more closely at Vivianite [Fe3(PO4)2-8(H2O)] and Siderite [FeCO3] in the next stage of the project.

Skorski, Daniel C.; Ryan, Joseph V.; Strachan, Denis M.; Lepry, William C.

2011-08-08

219

The fate of silicon during glass corrosion under alkaline conditions: A mechanistic and kinetic study with the International Simple Glass  

NASA Astrophysics Data System (ADS)

International Simple Glass - a six oxide borosilicate glass selected by the international nuclear glass community to improve the understanding of glass corrosion mechanisms and kinetics - was altered at 90 °C in a solution initially saturated with respect to amorphous 29SiO2. The pH90°C, was fixed at 9 at the start of the experiment and raised to 11.5 after 209 d by the addition of KOH. Isotope sensitive analytical techniques were used to analyze the solution and altered glass samples, helping to understand the driving forces and rate limiting processes controlling long-term glass alteration. At pH 9, the corrosion rate continuously drops and the glass slowly transforms into a uniform, homogeneous amorphous alteration layer. The mechanisms responsible for this transformation are water penetration through the growing alteration layer and ion exchange. We demonstrate that this amorphous alteration layer is not a precipitate resulting from the hydrolysis of the silicate network; it is mostly inherited from the glass structure from which the most weakly bonded cations (Na, Ca and B) have been released. At pH 11.5, the alteration process is very different: the high solubility of glass network formers (Si, Al, Zr) triggers the rapid and complete dissolution of the glass (dissolution becomes congruent) and precipitation of amorphous and crystalline phases. Unlike at pH 9 where glass corrosion rate decreased by 3 orders of magnitude likely due to the retroaction of the alteration layer on water dynamics/reactivity at the reaction front, the rate at pH 11.5 is maintained at a value close to the forward rate due to both the hydrolysis of the silicate network promoted by OH- and the precipitation of CSH and zeolites. This study provides key information for a unified model for glass dissolution.

Gin, Stéphane; Jollivet, Patrick; Fournier, Maxime; Berthon, Claude; Wang, Zhaoying; Mitroshkov, Alexandre; Zhu, Zihua; Ryan, Joseph V.

2015-02-01

220

CCMR: Study of Mixed Glass Former Phenomena in Glasses  

NSDL National Science Digital Library

Water concentration in varying compositions of sodium borosilicate glass was studied by Fourier Transform Infrared Spectroscopy. This is to further explore the Mixed Glass Former Effect (MGFE) in glasses with two or more network formers. Previous data shows that the water concentration increases with time.1 Thick and thin sample analysis was carried out on the glass to validate this data.

Clark, Braeden

2009-08-15

221

Infrared spectroscopy and hydrogen isotope geochemistry of hydrous silicate glasses  

SciTech Connect

The focus of this project is the combined appication of infrared spectroscopy and stable isotope geochemistry to the study of hydrogen-bearing species dissolved in silicate melts and glasses. We are conducting laboratory experiments aimed at determining the fractionation of D and H between melt species (OH and H{sub 2}O) and hydrous vapor and the diffusivities of these species in glasses and melts. Knowledge of these parameters is critical to understanding the behavior of hydrogen isotopes during igneous processes and hydrothermal processes. These results also could be valuable in application of glass technology to development of nuclear waste disposal strategies.

Epstein, S.; Stolper, E.

1992-01-01

222

Experimental hydration studies of natural and synthetic glasses  

SciTech Connect

The results of a series of hydration experiments on natural glasses (Hawaiian basalt, obsidian) and the nuclear waste glass WV-44 done to examine laboratory methods of accelerating reaction processes are summarized. The glasses were reacted in hydrothermal solution and in saturated vapor water. It was found that different reaction rates and processes were found using the differing conditions, and that laboratory efforts to accelerate and duplicate natural processes must amount for the physical processes that occur naturally. 18 refs., 5 figs., 1 tab.

Bates, J.K.; Abrajano, T.A. Jr.; Ebert, W.L.; Mazer, J.J.; Gerding, T.J.

1988-01-01

223

Slow Dynamics in Glasses  

E-print Network

Minimalist theories of complex systems are broadly of two kinds: mean-field and axiomatic. So far all theories of complex properties absent from simple systems and intrinsic to glasses are axiomatic. Stretched Exponential Relaxation (SER) is the prototypical complex temporal property of glasses, discovered by Kohlrausch 150 years ago, and now observed almost universally in microscopically homogeneous, complex non-equilibrium materials, including luminescent electronic (Coulomb) glasses. Critical comparison of alternative axiomatic theories with both numerical simulations and experiments strongly favors dynamical trap models over static percolative or energy landscape models. PACS: 61.20.Lc; 67.40.Fd

J. C. Phillips

2005-05-18

224

Phase coexistence in proton glass  

SciTech Connect

Proton glasses are crystals of composition M{sub 1{minus}x}(NW{sub 4}){sub x}W{sub 2}AO{sub 4}, where M = K,Rb, W = H,D, A = P,As. For x = 0 there is a ferroelectric (FE) transition, while for x = 1 there is an antiferroelectric (AFE) transition. In both cases, the transition is from a paraelectric (PE) state of tetragonal structure with dynamically disordered hydrogen bonds to an ordered state of orthorhombic structure. For an intermediate x range there is no transition, but the hydrogen rearrangements slow down, and eventually display nonergodic behavior characteristic of glasses. The authors and other have shown from spontaneous polarization, dielectric permittivity, nuclear magnetic resonance, and neutron diffraction experiments that for smaller x there is coexistence of ferroelectric and paraelectric phases, and for larger x there is coexistence of antiferroelectric and paraelectric phases. The authors present a method for analytically describing this coexistence, and the degree to which this coexistence is spatial or temporal.

Schmidt, V.H. [Montana State Univ., Bozeman, MT (United States). Physics Dept.; Trybula, Z. [Polish Academy of Sciences, Poznan (Poland). Inst. of Molecular Physics; Pinto, N.J. [Univ. of Puerto Rico, Humacao (Puerto Rico); Shapiro, S.M. [Brookhaven National Lab., Upton, NY (United States). Physics Dept.

1996-11-01

225

Molecular Mobility in Sugar Glasses  

Microsoft Academic Search

Glasses are liquids that exhibit solid state behavior as a result of their extremely high viscosity. Regarding their application to foods, glasses play a role in the preservation of foods, due to their high viscosity and the concomitant low molecular mobility. This thesis focuses on sugar glasses. Sugar glasses are relevant as model systems for foods that contain sugars and

Dries van den I. J

2000-01-01

226

Pourbaix diagram for the prediction of waste glass durability in geologic environments  

SciTech Connect

Dissolution of nuclear waste glass occurs by corrosion mechanisms similar to those of metallurgical and mineralogic systems albeit on different time scales. The effects of imposed pH and oxidation potential (Eh) conditions existing in natural environments on metals and minerals have been quantitatively and phenomenologically described in compendiums of Pourbaix (pH-potential) diagrams. Construction of Pourbaix diagrams to quantify the response of nuclear waste glasses to repository specific pH and Eh conditions is demonstrated. The expected long-term effects of groundwater contact on the durability of nuclear waste glasses can then be unified. 40 refs., 4 figs., 1 tab.

Jantzen, C.M.

1987-01-01

227

Super ionic conductive glass  

DOEpatents

An ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A.sub.1+x D.sub.2-x/3 Si.sub.x P.sub.3-x O.sub.12-2x/3, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

Susman, Sherman (Park Forest, IL); Volin, Kenneth J. (Fort Collins, CO)

1984-01-01

228

Nanostructure of metaphosphate glasses  

NASA Astrophysics Data System (ADS)

Glassy metaphosphates of one, two, and three valence metals were studied by Rayleigh and Mandel'shtam-Brilllouin scattering (RMBS) spectroscopy and high temperature ultrasonic (HTUS) measurements in glass melts. Ratios of Rayleigh scattering intensities to the Mandel'shtam-Brilllouin scattering ones (Landau-Placzek ratios) were measured. Results are discussed in terms of density, concentration, and anisotropy fluctuations "freezing" when the melt is being cooled to solid glass state. Combined application of RMBS and HTUS made it possible to independently estimate the contributions of "frozen-in" density and concentration fluctuations into Rayleigh scattering. It was found that in most cases about half Rayleigh scattering intensity is caused by chemical nanoinhomogeneities of a glass, that is the "frozen-in" concentration fluctuations. Comparison of RMBS, HTUS and small angle X ray scattering (SAXS) data led to the conclusion that NaPO3 and Ba(PO3)2 glasses were characterized by the highest chemical homogeneity on nanometer scale.

Maksimov, L. V.; Anan'ev, A. V.; Bogdanov, V. N.

2011-06-01

229

THE COLOR GLASS CONDENSATE.  

SciTech Connect

The Color Glass Condensate is a state of high density gluonic matter which controls the high energy limit of hadronic interactions. Its properties are important for the initial conditions for matter produced at RHIC.

MCLERRAN,L.

2001-08-26

230

CCMR: Water in Glass  

NSDL National Science Digital Library

Water uptake for various compositions of the model glass (Fe2O3)0.01(B2O3)0.048(Na2O)0.142(SiO2)0.8x(Al2O3)0.8(1âx) under fixed annealing conditions was studied via FTIR. Glasses of this formulation were found to take up water at both 300 and 380 °C. The time dependence of their water uptake entails that the governing kinetics are determined by the diffusion of water molecules in the glass network. The experimental approach used was validated by confirming previous water concentration results regarding glasses of the composition (Na2O)0.2[(BO1.5)x(SiO2)1âx]0.8.

Harrell, Stuart

2010-08-15

231

Seeing Glass Contractors Clearly.  

ERIC Educational Resources Information Center

Offers seven tips for finding and working with an effective glass contractor. For example, schools should consider the company's reputation and longevity of service, and whether it has in-house engineering capabilities. (EV)

Deliberato, Jerry

2003-01-01

232

8.G Glasses  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: The diagram shows three glasses (not drawn to scale). The measurements are all in centimeters. The bowl of glass 1 is cylindrical. The inside diameter ...

233

Metallic glass composition  

DOEpatents

A metallic glass alloy that is either iron-based or nickel-based or based on a mixture of iron and nickel, containing lesser amounts of elements selected from the group boron, silicon carbon and phosphorous to which is added an amount of a ductility enhancing element selected from the group cerium, lanthanum, praseodymium and neodymium sufficient to increase ductility of the metallic glass upon annealing.

Kroeger, Donald M. (Knoxville, TN); Koch, Carl C. (Raleigh, NC)

1986-01-01

234

Glass fiber insulation  

SciTech Connect

A composition for a glass fiber insulation is described comprising a loose mat of glass fibers having at least a portion of the surface coated with a water insoluble, non-hygroscopic, amorphous aluminum phosphate polymer having a molar ratio of Al[sub 2]O[sub 3] to P[sub 2]O[sub 5] of less than 1 and providing a substantial thermal resistance.

Griffith, E.J.; Ngo, T.M.

1993-06-29

235

Ductile Bulk Metallic Glass  

Microsoft Academic Search

We report on experimental evidence of pronounced global plasticity measured in monolithic Pt57.5Cu14.7Ni5.3P22.5 bulk metallic glass under both bending and unconfined compression loading conditions. A plastic strain of 20% is measured, never before seen in metallic glasses. Also, permanent deformation and a strain exceeding 3% before failure is observed during bending of 4mm thick samples. To date, no monolithic metallic

Jan Schroers; William L. Johnson

2004-01-01

236

Containerless synthesis of interesting glasses  

NASA Technical Reports Server (NTRS)

One aspect of containerless glass experimentation was thoroughly examined: glass forming ability. It is argued that although containerless processing will abet glass formation, other ground-based methods can do the job better. However, these methods have limitations, such as sample dimensions and concomitant ability to make property measurements. Most importantly, perhaps, is the observation that glass properties are a function of preparation procedure. Thus, it seems as though there still is an argument for use of containerless processing for glass forming.

Weinberg, Michael C.

1990-01-01

237

Towards ultrastrong glasses.  

PubMed

The development of new glassy materials is key for addressing major global challenges in energy, medicine, and advanced communications systems. For example, thin, flexible, and large-area glass substrates will play an enabling role in the development of flexible displays, roll-to-roll processing of solar cells, next-generation touch-screen devices, and encapsulation of organic semiconductors. The main drawback of glass and its limitation for these applications is its brittle fracture behavior, especially in the presence of surface flaws, which can significantly reduce the practical strength of a glass product. Hence, the design of new ultrastrong glassy materials and strengthening techniques is of crucial importance. The main issues regarding glass strength are discussed, with an emphasis on the underlying microscopic mechanisms that are responsible for mechanical properties. The relationship among elastic properties and fracture behavior is also addressed, focusing on both oxide and metallic glasses. From a theoretical perspective, atomistic modeling of mechanical properties of glassy materials is considered. The topological origin of these properties is also discussed, including its relation to structural and chemical heterogeneities. Finally, comments are given on several toughening strategies for increasing the damage resistance of glass products. PMID:22103001

Wondraczek, Lothar; Mauro, John C; Eckert, Jürgen; Kühn, Uta; Horbach, Jürgen; Deubener, Joachim; Rouxel, Tanguy

2011-10-18

238

Glass microsphere lubrication  

NASA Technical Reports Server (NTRS)

The harsh lunar environment eliminated the consideration of most lubricants used on earth. Considering that the majority of the surface of the moon consists of sand, the elements that make up this mixture were analyzed. According to previous space missions, a large portion of the moon's surface is made up of fine grained crystalline rock, about 0.02 to 0.05 mm in size. These fine grained particles can be divided into four groups: lunar rock fragments, glasses, agglutinates (rock particles, crystals, or glasses), and fragments of meteorite material (rare). Analysis of the soil obtained from the missions has given chemical compositions of its materials. It is about 53 to 63 percent oxygen, 16 to 22 percent silicon, 10 to 16 percent sulfur, 5 to 9 percent aluminum, and has lesser amounts of magnesium, carbon, and sodium. To be self-supporting, the lubricant must utilize one or more of the above elements. Considering that the element must be easy to extract and readily manipulated, silicon or glass was the most logical choice. Being a ceramic, glass has a high strength and excellent resistance to temperature. The glass would also not contaminate the environment as it comes directly from it. If sand entered a bearing lubricated with grease, the lubricant would eventually fail and the shaft would bind, causing damage to the system. In a bearing lubricated with a solid glass lubricant, sand would be ground up and have little effect on the system. The next issue was what shape to form the glass in. Solid glass spheres was the only logical choice. The strength of the glass and its endurance would be optimal in this form. To behave as an effective lubricant, the diameter of the spheres would have to be very small, on the order of hundreds of microns or less. This would allow smaller clearances between the bearing and the shaft, and less material would be needed. The production of glass microspheres was divided into two parts, production and sorting. Production includes the manufacturing of the microspheres, while sorting entails deciphering the good microspheres from the bad ones. Each process is discussed in detail.

Geiger, Michelle; Goode, Henry; Ohanlon, Sean; Pieloch, Stuart; Sorrells, Cindy; Willette, Chris

1991-01-01

239

Fabrication and characterization of MCC approved testing material - ATM12 glass  

Microsoft Academic Search

The Materials Characterization Center (MCC) Approved Testing Material ATM-12 is a borosilicate glass that incorporates elements typical of high-level waste (HLW) resulting from the reprocessing of commercial nuclear reactor fuels. The composition has been adjusted to match that predicted for HLW type 76-68 glass at an age of 300 y. Radioactive constituents contained in this glass include depleted uranium, Tc,

Wald

1985-01-01

240

Failure analysis of the lithium battery: A study of the header deposit on the cell top and diffusion within the electrode glass seal using nuclear microanalysis and FFTIR spectroscopy  

Microsoft Academic Search

The Solid Rocket Booster Range Safety System (SRBRSS) uses a lithium\\/poly-carbon monofluoride primary battery as a source of electrical power. After cell fabrication and activation, some battery cells have shown self discharge. One possible source of this cell discharge has been suggested to be the formation and growth of a conducting crystallized chemical compound across the glass bead insulator, electrically

Razi A. Hassan

1991-01-01

241

Glass matrix armor  

DOEpatents

An armor system which utilizes glass. A plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile-receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the inside surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material consisting of glass and a ceramic material and, in certain embodiments, a polymeric material. The glass may be in monolithic form or particles of ceramic may be dispersed in a glass matrix. The ceramic material may be in monolithic form or may be in the form of particles dispersed in glass or dispersed in said polymer.

Calkins, Noel C. (Los Alamos, NM)

1991-01-01

242

Sol-Gel Glasses  

NASA Technical Reports Server (NTRS)

Multicomponent homogeneous, ultrapure noncrystalline gels/gel derived glasses are promising batch materials for the containerless glass melting experiments in microgravity. Hence, ultrapure, homogeneous gel precursors could be used to: (1) investigate the effect of the container induced nucleation on the glass forming ability of marginally glass forming compositions; and (2) investigate the influence of gravity on the phase separation and coarsening behavior of gel derived glasses in the liquid-liquid immiscibility zone of the nonsilicate systems having a high density phase. The structure and crystallization behavior of gels in the SiO2-GeO2 as a function of gel chemistry and thermal treatment were investigated. As are the chemical principles involved in the distribution of a second network former in silica gel matrix being investigated. The procedures for synthesizing noncrystalline gels/gel-monoliths in the SiO2-GeO2, GeO2-PbO systems were developed. Preliminary investigations on the levitation and thermal treatment of germania silicate gel-monoliths in the Pressure Facility Acoustic Levitator were done.

Mukherjee, S. P.

1985-01-01

243

Prediction of radioactive waste glass durability by the hydration thermodynamic model: Application to saturated repository environments  

SciTech Connect

The effects of groundwater chemistry on glass durability were examined using the hydration thermodynamic model. The relative durabilities of SiO{sub 2}, obsidians, basalts, nuclear waste glasses, medieval window glasses, and a frit glass were determined in tuffaceous groundwater, basaltic groundwater, WIPP-A brine, and Permian-A brine using the monolithic MCC-1 durability test. For all the groundwaters, the free energy of hydration, calculated from the glass composition and the final experimental pH, was linearly related to the logarithm of the measured silica concentration. The linear equation was identical to that observed previously for these glasses during MCC-1 testing in deionized water. In the groundwater-dominated MCC-1 experiments, the pH values for all the glasses tested appeared to be buffered by the groundwater-precipitate chemistry. The behavior of poorly durable glasses demonstrated that the silica release is a function of the ionic strength of the solution. The ionic strength, in turn, reflects the effect of the groundwater chemistry on the pH. Using the hydration thermodynamic model, nuclear waste glass durability in saturated repository environments can be predicted from the glass composition and the groundwater and the groundwater pH. 47 refs., 3 figs. 1 tab.

Jantzen, C.M. (Westinghouse Savannah River Co., Aiken, SC (USA)); Ramsey, W.G. (Clemson Univ., SC (USA). Dept. of Ceramic Engineering)

1989-01-01

244

THE INFLUENCE OF RADIATION AND MULTIVALENT CATION ADDITIONS ON PHASE SEPARATION AND CRYSTALLIZATION OF GLASS  

EPA Science Inventory

Recent reviews which have dealt with critical issues regarding the suitability of glasses for nuclear waste disposal have identified liquid-liquid immiscibility and crystallization processes as having the potential to alter significantly storage behavior, especially chemical corr...

245

Porous vycor glass tube joined to borosilicate glass  

NASA Astrophysics Data System (ADS)

Porous glass can absorb various size of molecules with large surface area even in high temperature. However, it is difficult to use porous glass tubes at high-temperature, for example as a separation membrane for hydrogen condensation, because adhesives at joining sites could be damaged. In this study, welding of a porous glass tube and a glass tube was attempted to develop a gas separation membrane used at 500 C. Since forms present in porous glass may cause crack at high temperature, it is necessary to remove such forms by heat processing. Such porous glass is called to be porous vycor glass, which contains quartz 6 percents, and can be joined with a quartz tube. As a result, a gas separator with porous glass membrane which is joined by this process could endure high temperature up to 600 C and could maintain high vacuum.

Abe, Shinichi; Kikuchi, Takemitsu; Onodera, Shinji

1992-09-01

246

Laser zone texturing on glass and glass-ceramic substrates  

Microsoft Academic Search

A RF driven CO2 laser is used to create laser bumps on glass and glass-ceramic substrates. The resulting bump height is found to be a function of laser parameters such as pulse width, spot size, and pulse energy. Composition, structure and chemical strengthening of the substrates also affect the laser bump topography. Laser bumps on glass-ceramic, non-strengthened glass, or strengthened

David Kuo; Stan D. Vierk; O. Rauch; Don Polensky

1997-01-01

247

Parametric effects on glass reaction in the unsaturated test method  

SciTech Connect

The Unsaturated Test Method has been applied to study glass reaction under conditions that may be present at the potential Yucca Mountain site, currently under evaluation for storage of reprocessed high-level nuclear waste. The results from five separate sets of parametric experiments are presented wherein test parameters ranging from water contact volume to sensitization of metal in contact with the glass were examined. The most significant effect was observed when the volume of water, as controlled by the water inject volume and interval period, was such to allow exfoliation of reacted glass to occur. The extent of reaction was also influenced to a lesser extent by the degree of sensitization of the 304L stainless steel. For each experiment, the release of cations from the glass and alteration of the glass were examined. The major alteration product is a smectite clay that forms both from precipitation from solution and from in-situ alteration of the glass itself. It is this clay that undergoes exfoliation as water drips from the glass. A comparison is made between the results of the parametric experiments with those of static leach tests. In the static tests the rates of release become progressively reduced through 39 weeks while, in contrast, they remain relatively constant in the parametric experiments for at least 300 weeks. This differing behavior may be attributable to the dripping water environment where fresh water is periodically added and where evaporation can occur.

Woodland, A.B.; Bates, J.K.; Gerding, T.J.

1991-12-01

248

Attenuation of Glass Dissolution in the Presence of Natural Additives  

NASA Technical Reports Server (NTRS)

The study described here explored the dissolution kinetics of glasses in aqueous environments in systems which included a variety of natural crystalline solids in addition to the glass itself and the aqueous phase. The results demonstrated the possibility of a dramatic decrease in the rate of dissolution of silicate glass in the presence of certain varieties of olivine-based materials. This decrease in dissolution rate was shown to be due to the fact that these additives consist mostly of Mg-based material but also contain minor amounts of Al and Ca. The combined presence of Mg with these minor species affected the corrosion rate of the glass as a whole, including its most soluble components such as boron. The study has potentially important implications to the durability of glasses exposed to natural environments. The results may be relevant to the use of active backfill materials in burial sites for nuclear waste glasses as well as to better understanding of the environmental degradation of natural and ancient glasses.

Sang, Jing C.; Barkatt, Aaron; OKeefe, John A.

1993-01-01

249

Glass ceramic toughened with tetragonal zirconia  

DOEpatents

A phase transformation-toughened glass ceramic and a process for making it are disclosed. A mixture of particulate network-forming oxide, network-modifying oxide, and zirconium oxide is heated to yield a homogeneous melt, and this melt is then heat treated to precipitate an appreciable quantity of tetragonal zirconia, which is retained at ambient temperature to form a phase transformation-toughened glass ceramic. Nuclearing agents and stabilizing agents may be added to the mixture to facilitate processing and improve the ceramic's properties. Preferably, the mixture is first melted at a temperature from 1200 to 1700/sup 0/C and is then heat-treated at a temperature within the range of 800 to 1200/sup 0/C in order to precipitate tetragonal ZrO/sub 2/. The composition, as well as the length and temperature of the heat treatment, must be carefully controlled to prevent solution of the precipitated tetragonal zirconia and subsequent conversion to the monoclinic phase.

Keefer, K.D.

1984-02-10

250

Transient nucleation in glasses  

NASA Technical Reports Server (NTRS)

Nucleation rates in condensed systems are frequently not at their steady state values. Such time dependent (or transient) nucleation is most clearly observed in devitrification studies of metallic and silicate glasses. The origin of transient nucleation and its role in the formation and stability of desired phases and microstructures are discussed. Numerical models of nucleation in isothermal and nonisothermal situations, based on the coupled differential equations describing cluster evolution within the classical theory, are presented. The importance of transient nucleation in glass formation and crystallization is discussed.

Kelton, K. F.

1991-01-01

251

Examination of glass-silicon and glass-glass bonding techniques for microfluidic systems  

NASA Astrophysics Data System (ADS)

We report here on the results of experiments concerning particular bonding processes potentially useful for ultimate miniaturization of microfluidic systems. Direct anodic bonding of continuous thin pyrex glass of 250 micrometers thickness to silicon substrates gives multiple, large voids in the glass. Etchback of thick glass of 1200 micrometers thickness bonded to silicon substrates gives thin continuous glass layers of 189 micrometers thickness without voids over areas of 5 cm X 12 cm. Glass was also successfully bonded to glass by thermal bonding at 800 degrees C over a 5 cm X 7 cm area. Anticipated applications include microfabricated DNA sequencing, flow injection analysis, and liquid and gas chromatography microinstruments.

Raley, Norman F.; Davidson, J. Courtney; Balch, Joseph W.

1995-09-01

252

Neutron-sensing scintillating glass optical fiber detectors  

SciTech Connect

Pacific Northwest Laboratory (PNL) has developed and tested the highest-transmission neutron-sensing glass fibers reported in the open literature to date. By developing glass compositions specifically for fiber drawing and by using superior oxidationstate controls and rapid quenching, PNL produces, fiber with useful lengths in excess of 200 cm. These long fibers can be used in detectors. Test results on the fibers used as a form-fitting detector around a small storage container containing neutron and gamma ray sources are reported. Excellent neutron-gamma ray discrimination has been achieved. These neutron-sensing glass optical fibers provide for new methods for monitoring the inventory of, preventing the diversion of, and detecting the unauthorized transport of sensitive nuclear materials. As such, it represents a significant potential element in countering the threat of nuclear terrorism.

Bliss, M.; Reeder, P.L.; Craig, R.A.

1994-07-01

253

On the strength of glass  

NASA Astrophysics Data System (ADS)

Glass has been ignored by most of the structural engineering community because of its brittle nature. Glass is an indispensable material in optical systems and sometimes safety, even human safety, depends upon optical glass elements to behave in a structurally reliable manner. One such occasion is to accommodate survey cameras in transport-class aircraft. Fortunately, glass has reliable structural properties and the methods for structural analysis and testing for glass have been well developed. Unfortunately, the glass suppliers have not chosen to publish the appropriate strength properties for many of their glasses. This paper describes the physics of the strength of glass and the engineering application of that physics to an airborne survey aircraft for the safety of its inhabitants.

Hatheway, Alson E.

2013-09-01

254

Containerless processing of fluoride glass  

NASA Technical Reports Server (NTRS)

Ground-based experiments on glass formation, crystallization, surface tension, vaporization, and chemical durability of a zirconium-barium-lanthanum (ZBL) fluoride glass are summarized. In a container large, columnar grains grew out from the container-glass interface during cooling. The main crystalline phase was alpha BaZrF6. A ZBL glass sphere was levitated acoustically during Shuttle flight STS-11. The glass was melted and then cooled while being levitated (containerless). Crystallization in the recovered sample was very fine and mainly beta BaZr2F10, showing the influence of the container on the nucleation and microstructure of crystallization in the glass. Glass formation should be easier for a containerless glass than in a container.

Doremus, Robert H.

1990-01-01

255

THE DEVELOPMENT OF RADIOACTIVE GLASS SURROGATES FOR FALLOUT DEBRIS  

SciTech Connect

The production of glass that emulates fallout is desired for the nuclear forensics community for training and measurement exercises. The composition of nuclear fallout is complex varying isotopic compositions . As the gaseous cloud traverses from hotter to cooler regions of the atmosphere, the processes of condensation and nucleation entrain environmental materials, vaporized nuclear materials and fission products. The elemental and isotopic composition of the fission products is altered due to chemical fractionation (i.e. the fission product composition that would be expected from fission of the original nuclear material is altered by differences in condensation rates of the elements); the fallout may be enriched or depleted in volatile or refractory fission products. This work describes preliminary results to synthesize, irradiate and fractionate the fission product content of irradiated particulate glass using a thermal distillation two hours after irradiation. The glass was synthesized using a solution-based polymerization of tetraethyl orthosilicate. Uranium was incorporated into the glass particulate at trace concentrations during polymerization. The particulate was subjected to a short thermal neutron irradiation then heated to 1273 K approximately 2 hours after the end of irradiation. Fission products of 133, 134, 135I, 132, 134Te, 135Xe, 138Cs and 91, 92Sr were observed to be distilled from the particulate. The results of these preliminary studies are discussed.

Martha R. Finck; Leigh R. Martin; Russel R. Lewis; Kevin P. Carney; Christopher A. McGrath

2014-01-01

256

Yesterday's Trash Makes Tomorrow's "Glass"  

ERIC Educational Resources Information Center

In this article, the author describes a glass art project inspired by Dale Chihuly. This project uses two-liter plastic soda bottles which are cut apart and trimmed. Applying heat using a hair dryer, the plastic curls and takes an uneven blown-glass quality. The "glass" is then painted using acrylic paint. (Contains 2 resources and 1 online…

Wayne, Dale

2010-01-01

257

The Color Glass Condensate  

E-print Network

We provide a broad overview of the theoretical status and phenomenological applications of the Color Glass Condensate effective field theory describing universal properties of saturated gluons in hadron wavefunctions that are extracted from deeply inelastic scattering and hadron-hadron collision experiments at high energies.

F. Gelis; E. Iancu; J. Jalilian-Marian; R. Venugopalan

2010-02-01

258

Stained-Glass Pastels  

ERIC Educational Resources Information Center

The author has always liked the look of stained-glass windows. Usually the designs are simplified and the shapes are easier for younger students to draw. This technique seemed to be the perfect place for her fifth-graders to try their hand at color mixing. The smaller spaces and simple shapes were just what she needed for this group. Her students…

Laird, Shirley

2009-01-01

259

Nanostructure of metaphosphate glasses  

Microsoft Academic Search

Glassy metaphosphates of one, two, and three valence metals were studied by Rayleigh and Mandel'shtam-Brilllouin scattering (RMBS) spectroscopy and high temperature ultrasonic (HTUS) measurements in glass melts. Ratios of Rayleigh scattering intensities to the Mandel'shtam-Brilllouin scattering ones (Landau-Placzek ratios) were measured. Results are discussed in terms of density, concentration, and anisotropy fluctuations \\

L. V. Maksimov; A. V. Anan'ev; V. N. Bogdanov

2011-01-01

260

Glass-matrix biocomposites.  

PubMed

CaO-SiO(2) base glass-matrix/Ti particle biocomposite coatings on Ti6Al4V substrates have been prepared by means of Vacuum Plasma Spray. The base glass is considered bioactive, because, when soaked in a fluid that simulates the inorganic ion concentration of human plasma (SBF), it develops a bonelike apatite layer on its surface. The aim of this research activity was to toughen this brittle bioactive material and to broaden its biomedical applications. Pure titanium was chosen as toughening phase because of its well-known biocompatibility, and Ti6Al4V alloy as substrate because of both its biocompatibility and its mechanical reliability. At first the composites were prepared as bulk materials, by means of a simple sintering process. Then, by ball-milling the sintered composite, the as-obtained "composite powders" were sprayed by Vacuum Plasma Spray (VPS) on the substrate. By means of Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC), the characteristic temperatures of the base glasses were determined. The thermal properties of mixtures of glass powders and different vol% Ti particles were studied by means of DTA, DSC, hot-stage microscopy, and dilatometry, with the aim of optimizing the sintering conditions. Both the bulk and the coated samples have been characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), compositional analysis (EDS), Vickers indentations, and leaching tests after soaking in a simulated body fluid (SBF). PMID:10898882

Verné, E; Brovarone, C V; Milanese, D

2000-01-01

261

Laser damage in glasses  

Microsoft Academic Search

Results are described which suggest that a laser beam focused inside a sample of glass produces a superheated liquid, and that the resulting internal pressure can only be released by internal fracturing, and, in some cases, also by fragmentation of the sample. The evidence is that the Brillouin scattered energy, demonstrated by Chiao, Townes, and Stoicheff is necessary, but not

D W Harper

1965-01-01

262

Triad ''Metal – Enamel – Glass''  

NASA Astrophysics Data System (ADS)

This article shows how to change the color of metal and glass. Both these materials are self–sufficient, but sometimes used together. For example, enameling. In this case, the adhesion between metal substrate and stekloobraznae enamel layer, which was conducted on a stretching and a bend, was tested.

Mukhina, T.; Petrova, S.; Toporova, V.; Fedyaeva, T.

2014-10-01

263

Volcanic glass as a natural analog for borosilicate waste glass  

SciTech Connect

Obsidian and basaltic glass are opposite end-members of natural volcanic glass compositions. Syngenetic and diagenetic tensile failure in basaltic glass (low silica glass) is pervasive and provides abundant alteration fronts deep into the glass structure. Perlitic fracturing in obsidian (high silica glass) limits the alteration zones to an {open_quotes}onion skin{close_quotes} geometry. Borosilicate waste glass behaves similarly to the natural analog of basaltic glass (sideromelane). During geologic time, established and tensile fracture networks form glass cells (a three-dimensional reticulated pattern) where the production of new fracture surfaces increases through time by geometric progression. This suggests that borosilicate glass monoliths will eventually become rubble. Rates of reaction appear to double for every 12C{degrees} of temperature increase. Published leach rates suggest that the entire inventory of certain radionuclides may be released during the 10,000 year regulatory time period. Steam alteration prior to liquid attack combined with pervasive deep tensile failure behavior may suggest that the glass waste form is not license defensible without a metallic- and/or ceramic-type composite barrier as an overpack.

Morgenstein, M.E.; Shettel, D.L. [Geosciences Management Institute, Inc., Boulder City, NV (United States)

1994-12-31

264

Apollo 12 ropy glasses revisited  

NASA Technical Reports Server (NTRS)

We analyzed ropy glasses from Apollo 12 soils 12032 and 12033 by a variety of techniques including SEM/EDX, electron microprobe analysis, INAA, and Ar-39-Ar-40 age dating. The ropy glasses have potassium rare earth elements phosphorous (KREEP)-like compositions different from those of local Apollo 12 mare soils; it is likely that the ropy glasses are of exotic origin. Mixing calculations indicate that the ropy glasses formed from a liquid enriched in KREEP and that the ropy glass liquid also contained a significant amount of mare material. The presence of solar Ar and a trace of regolith-derived glass within the ropy glasses are evidence that the ropy glasses contain a small regolith component. Anorthosite and crystalline breccia (KREEP) clasts occur in some ropy glasses. We also found within these glasses clasts of felsite (fine-grained granitic fragments) very similar in texture and composition to the larger Apollo 12 felsites, which have a Ar-39-Ar-40 degassing age of 800 +/- 15 Ma. Measurements of 39-Ar-40-Ar in 12032 ropy glass indicate that it was degassed at the same time as the large felsite although the ropy glass was not completely degassed. The ropy glasses and felsites, therefore, probably came from the same source. Most early investigators suggested that the Apollo 12 ropy glasses were part of the ejecta deposited at the Apollo 12 site from the Copernicus impact. Our new data reinforce this model. If these ropy glasses are from Copernicus, they provide new clues to the nature of the target material at the Copernicus site, a part of the Moon that has not been sampled directly.

Wentworth, S. J.; Mckay, D. S.; Lindstrom, D. J.; Basu, A.; Martinez, R. R.; Bogard, D. D.; Garrison, D. H.

1994-01-01

265

The formation of crystals in glasses containing rare earth oxides  

NASA Astrophysics Data System (ADS)

Korean spent nuclear fuel will reach the capacity of the available temporary storage by 2016. Pyroprocessing and direct disposal seems to be an alternative way to manage and reuse spent nuclear fuel while avoiding the wet reprocessing technology. Pyroprocessing produces several wastes streams, including metals, salts, and rare earths, which must be converted into stabilized form. A suitable form for rare earth immobilization is borosilicate glass. The borosilicate glass form exhibits excellent durability, allows a high waste loading, and is easy to process. In this work, we combined the rare earths waste of composition (in wt%) 39.2Nd2O3-22.7CeO2-11.7La2O3-10.9PrO2-1.3Eu2O3-1.3Gd2O3-8.1Sm2O3-4.8Y2O3 with a baseline glass of composition 60.2SiO2-16.0B2O3-12.6Na2O-3.8Al2O3-5.7CaO-1.7ZrO2. Crystallization in waste glasses occurs as the waste loading increases. It may produce complicate glass processing and affect the product quality. To study crystal formation, we initially made glasses containing 5%, 10% and 15% of La2O3 and then glasses with 5%, 10% and 15% of the complete rare earth mix. Samples were heat-treated for 24 hours at temperatures 800°C to 1150°C in 50°C increments. Quenched samples were analyzed using an optical microscope, scanning electron microscope with energy dispersive spectroscopy, and x-ray diffraction. Stillwellite (LaBSiO5) and oxyapatite (Ca2La8Si6O26) were found in glasses containing La2O3, while oxyapatite (Ca2La8Si6O26 and NaNd9Si6O26) precipitated in glasses with additions of mixed rare earths. The liquidus temperature (TL) of the glasses containing 5%, 10% and 15% La2O3 were 800°C, 959°C and 986°C, respectively; while TL was 825°C, 1059°C and 1267°C for glasses with 5%, 10% and 15% addition of mixed rare earth oxides. The component coefficients TB2O3, TSiO2, TCaO, and TRE2O3 were also evaluated using a recently published study.

Fadzil, Syazwani Mohd; Hrma, Pavel; Crum, Jarrod; Siong, Khoo Kok; Ngatiman, Mohammad Fadzlee; Said, Riduan Mt

2014-02-01

266

Production of glass or glass-ceramic to metal seals with the application of pressure  

DOEpatents

In a process for preparing a glass or glass-ceramic to metal seal comprising contacting the glass with the metal and heat-treating the glass and metal under conditions whereby the glass to metal seal is effected and, optionally, the glass is converted to a glass-ceramic, an improvement comprises carrying out the heat-treating step using hot isostatic pressing.

Kelly, Michael D. (West Alexandria, OH); Kramer, Daniel P. (Dayton, OH)

1987-11-10

267

Production of glass or glass-ceramic to metal seals with the application of pressure  

DOEpatents

In a process for preparing a glass or glass-ceramic to metal seal comprising contacting the glass with the metal and heat-treating the glass and metal under conditions whereby the glass to metal seal is effected and, optionally, the glass is converted to a glass-ceramic, an improvement comprises carrying out the heat-treating step using hot isostatic pressing.

Kelly, M.D.; Kramer, D.P.

1985-01-04

268

Profiles in garbage glass containers  

SciTech Connect

Glass containers are made from sand, limestone, soda ash, cullet (crushed bottles), and various additives, including those used to color brown, green, or blue bottles. Sixty percent of the glass used in the US is clear (flint) and one-fourth is brown (amber). Almost half of the green bottles are imported wind and beer bottles. Other glass products include flat glass such as windows; fiberglass insulation; and glassware. These products use different manufacturing processes and different additives than container glass. This profile covers only container glass. Glass bottles are commonly collected in curb-side programs. Losses due to breakage and the abrasiveness of glass during collection and processing offset their low collection and processing costs. Breakage solutions include installation of interior baffles or nets in the collection trucks, special glass-only truck compartments, and limiting the number of times glass is transferred after collection before final processing. Ten states require deposits on glass bottles for beer and soft drinks and related items.

Miller, C. [Environmental Industry Associations, Washington, DC (United States)

1997-09-01

269

Interactions of silicate glasses with aqueous environments under conditions of prolonged contact and flow  

NASA Technical Reports Server (NTRS)

This paper discusses mechanisms involving saturation and reactions that lead to the formation of altered phases in silicate glasses considered for use in geologic repositories for nuclear waste. It is shown that the rate of dissolution of silicate glasses exposed to a broad range of contact times, leachant compositions, and surface-to-volume ratios is strongly affected by the presence of reactive species such as Al, Mg, and Fe. The reactive materials may originate in the leachant or, under conditions of high surface-to-volume ratio, in the glass itself. The effects of glass composition on the course of the corrosion process can be viewed in terms of the formation of a surface layer on the leached glass; the type, composition, and structure of this layer control the dissolution behavior of the glass.

Barkatt, Aaron; Saad, E. E.; Adiga, R. B.; Sousanpour, W.; Barkatt, AL.; Feng, X.; O'Keefe, J. A.; Alterescu, S.

1988-01-01

270

Molten Glass for Thermal Storage: Advanced Molten Glass for Heat Transfer and Thermal Energy Storage  

SciTech Connect

HEATS Project: Halotechnics is developing a high-temperature thermal energy storage system using a new thermal-storage and heat-transfer material: earth-abundant and low-melting-point molten glass. Heat storage materials are critical to the energy storage process. In solar thermal storage systems, heat can be stored in these materials during the day and released at night—when the sun is not out—to drive a turbine and produce electricity. In nuclear storage systems, heat can be stored in these materials at night and released to produce electricity during daytime peak-demand hours. Halotechnics new thermal storage material targets a price that is potentially cheaper than the molten salt used in most commercial solar thermal storage systems today. It is also extremely stable at temperatures up to 1200°C—hundreds of degrees hotter than the highest temperature molten salt can handle. Being able to function at high temperatures will significantly increase the efficiency of turning heat into electricity. Halotechnics is developing a scalable system to pump, heat, store, and discharge the molten glass. The company is leveraging technology used in the modern glass industry, which has decades of experience handling molten glass.

None

2012-01-01

271

Ductile Bulk Metallic Glass  

NASA Astrophysics Data System (ADS)

We report on experimental evidence of pronounced global plasticity measured in monolithic Pt57.5Cu14.7Ni5.3P22.5 bulk metallic glass under both bending and unconfined compression loading conditions. A plastic strain of 20% is measured, never before seen in metallic glasses. Also, permanent deformation and a strain exceeding 3% before failure is observed during bending of 4mm thick samples. To date, no monolithic metallic material has exhibited such a combination of high strength, extensive ductility, and high elastic limit. The large plasticity is reflected in a high Poisson ratio of 0.42, which causes the tip of a shear band to extend rather than initiate a crack. This results in the formation of multiple shear bands and is the origin of the observed large global ductility and very high fracture toughness, approximately 80 MPa m-1/2.

Schroers, Jan; Johnson, William L.

2004-12-01

272

Ductile bulk metallic glass.  

PubMed

We report on experimental evidence of pronounced global plasticity measured in monolithic Pt57.5Cu14.7Ni5.3P22.5 bulk metallic glass under both bending and unconfined compression loading conditions. A plastic strain of 20% is measured, never before seen in metallic glasses. Also, permanent deformation and a strain exceeding 3% before failure is observed during bending of 4 mm thick samples. To date, no monolithic metallic material has exhibited such a combination of high strength, extensive ductility, and high elastic limit. The large plasticity is reflected in a high Poisson ratio of 0.42, which causes the tip of a shear band to extend rather than initiate a crack. This results in the formation of multiple shear bands and is the origin of the observed large global ductility and very high fracture toughness, approximately 80 MPa m(-1/2). PMID:15697909

Schroers, Jan; Johnson, William L

2004-12-17

273

CCMR: Water in Glass  

NSDL National Science Digital Library

Water uptake for various compositions of the model glass (CaO·Al2O3)x (2 SiO2)1-x under fixed annealing conditions was studied via FTIR. The water saturation concentration increased with time for certain sample sets, suggesting slow equilibration of the surface with the annealing atmosphere, while the water diffusion coefficient exhibited no appreciable time dependence. The saturation concentration and diffusion coefficient were not found to vary significantly with composition.

Uspal, William

2005-08-17

274

Structure and Chemistry in Halide Lead-Tellurite Glasses  

SciTech Connect

A series of TeO2-PbO glasses were fabricated with increasing fractions of mixed alkali, alkaline earth, and lanthanide chlorides. The glass and crystal structure was studied with Raman spectroscopy, nuclear magnetic resonance (NMR), X-ray diffraction, and electron microscopy. As the chloride fraction increased, the medium-range order in the glass decreased up to a critical point (~14 mass% of mixed chlorides), above which the glasses became phase-separated. Resulting phases are a TeO2/PbO-rich phase and a crystalline phase rich in alkali chlorides. The 125Te NMR indicates, contrary to previous studies, that Te site distribution did not change with increased concentrations of M+, M2+, and M3+ cations, but rather is controlled by the Te/Pb molar ratio. The 207Pb NMR shows that two Pb species exist and their relative concentration changes nearly linearly with addition of the mixed chlorides, indicating that the additives to the TeO2-PbO glass are accommodated by changing the Pb species. The 23Na and 35Cl NMR indicate that Na and Cl are distributed in the single-phase glass phase up to the critical point, and at higher concentrations partition to crystalline phases. Transmission electron microscopy shows that the sample at the critical point contains ~10 nm seed nuclei that increase in size and concentration with exposure to the electron beam.

McCloy, John S.; Riley, Brian J.; Lipton, Andrew S.; Windisch, Charles F.; Washton, Nancy M.; Olszta, Matthew J.; Rodriguez, Carmen P.

2013-02-11

275

Incorporation and Speciation of Sulphur in Glasses for Waste Immobilization  

SciTech Connect

The incorporation and speciation of sulphur in glass compositions relevant to the immobilisation of nuclear and toxic wastes has been investigated; and for the first time we present a detailed analysis of S-bearing phosphate glasses. Sulphur K edge x-ray absorption near edge structure (XANES) has provided detailed information on the oxidation state of sulphur. It confirms that in phosphate glasses prepared under oxidising conditions, sulphur is present as sulphate, SO{sub 4}{sup 2-}. Linear relationships have been identified linking log[SO{sub 3}] (mol%) with the oxygen ion activity, which can be represented by the normalised cation field strength index {Sigma}(z/s{sup 2}). When prepared under oxidising conditions only basic, highly depolymerised phosphate glasses for which {Sigma}(z/a{sup 2})<{approx}1{center_dot}2 can incorporate levels of sulphur that would be considered useful from a waste immobilisation perspective. When glasses are evaluated within familial limits, this methodology provides a useful tool for predicting sulphur capacity and designing new glass compositions that can safely incorporate greater levels of sulphur.

Bingham, P.; Connelly, A; Hand, R; Hyatt, N; Northrup, P

2009-01-01

276

Structure, biodegradation behavior and cytotoxicity of alkali-containing alkaline-earth phosphosilicate glasses.  

PubMed

We report on the effect of sodium on the structure, chemical degradation and bioactivity of glasses in the CaO-MgO-SiO2-P2O5-CaF2 system. The (29)Si and (31)P magic angle spinning-nuclear magnetic resonance spectroscopy of melt-quenched glasses with varying Na2O/MgO ratios exhibit a silicate glass network with the dominance of Q(2)(Si) units and phosphorus mainly forming orthophosphate species. Sodium incorporation in the glasses did not induce a significant structural change in the silicate network, while it did influence the phosphate environment due to its lower ionic field strength in comparison with that of magnesium. The apatite forming ability of glasses has been investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1h and 7 days while their chemical degradation has been studied in Tris-HCl in accordance with ISO-10993-14. Increasing Na(+)/Mg(2+) ratio caused a decrease in the chemical durability of glasses and in the apatite forming ability especially during initial steps of interaction between glass and SBF solution. The cellular responses were observed in vitro on bulk glass samples using mouse-derived pre-osteoblastic MC3T3-E1 cell line. The preliminary study suggested that the increasing alkali-concentration in glasses led to cytotoxicity in the cell culture medium. PMID:25280692

Kansal, Ishu; Reddy, AlluAmarnath; Muñoz, Francisco; Choi, Seong-Jun; Kim, Hae-Won; Tulyaganov, Dilshat U; Ferreira, José M F

2014-11-01

277

Cluster-assembled metallic glasses  

PubMed Central

A bottom-up approach to nanofabricate metallic glasses from metal clusters as building blocks is presented. Considering metallic glasses as a subclass of cluster-assembled materials, the relation between the two lively fields of metal clusters and metallic glasses is pointed out. Deposition of selected clusters or collections of them, generated by state-of-the-art cluster beam sources, could lead to the production of a well-defined amorphous material. In contrast to rapidly quenched glasses where only the composition of the glass can be controlled, in cluster-assembled glasses, one can precisely control the structural building blocks. Comparing properties of glasses with similar compositions but differing in building blocks and therefore different in structure will facilitate the study of structure–property correlation in metallic glasses. This bottom-up method provides a novel alternative path to the synthesis of glassy alloys and will contribute to improving fundamental understanding in the field of metallic glasses. It may even permit the production of glassy materials for alloys that cannot be quenched rapidly enough to circumvent crystallization. Additionally, gaining deeper insight into the parameters governing the structure–property relation in metallic glasses can have a great impact on understanding and design of other cluster-assembled materials. PMID:23899019

2013-01-01

278

Cluster-assembled metallic glasses.  

PubMed

A bottom-up approach to nanofabricate metallic glasses from metal clusters as building blocks is presented. Considering metallic glasses as a subclass of cluster-assembled materials, the relation between the two lively fields of metal clusters and metallic glasses is pointed out. Deposition of selected clusters or collections of them, generated by state-of-the-art cluster beam sources, could lead to the production of a well-defined amorphous material. In contrast to rapidly quenched glasses where only the composition of the glass can be controlled, in cluster-assembled glasses, one can precisely control the structural building blocks. Comparing properties of glasses with similar compositions but differing in building blocks and therefore different in structure will facilitate the study of structure-property correlation in metallic glasses. This bottom-up method provides a novel alternative path to the synthesis of glassy alloys and will contribute to improving fundamental understanding in the field of metallic glasses. It may even permit the production of glassy materials for alloys that cannot be quenched rapidly enough to circumvent crystallization. Additionally, gaining deeper insight into the parameters governing the structure-property relation in metallic glasses can have a great impact on understanding and design of other cluster-assembled materials. PMID:23899019

Kartouzian, Aras

2013-01-01

279

Bioactive glass in tissue engineering  

PubMed Central

This review focuses on recent advances in the development and use of bioactive glass for tissue engineering applications. Despite its inherent brittleness, bioactive glass has several appealing characteristics as a scaffold material for bone tissue engineering. New bioactive glasses based on borate and borosilicate compositions have shown the ability to enhance new bone formation when compared to silicate bioactive glass. Borate-based bioactive glasses also have controllable degradation rates, so the degradation of the bioactive glass implant can be more closely matched to the rate of new bone formation. Bioactive glasses can be doped with trace quantities of elements such as Cu, Zn and Sr, which are known to be beneficial for healthy bone growth. In addition to the new bioactive glasses, recent advances in biomaterials processing have resulted in the creation of scaffold architectures with a range of mechanical properties suitable for the substitution of loaded as well as non-loaded bone. While bioactive glass has been extensively investigated for bone repair, there has been relatively little research on the application of bioactive glass to the repair of soft tissues. However, recent work has shown the ability of bioactive glass to promote angiogenesis, which is critical to numerous applications in tissue regeneration, such as neovascularization for bone regeneration and the healing of soft tissue wounds. Bioactive glass has also been shown to enhance neocartilage formation during in vitro culture of chondrocyte-seeded hydrogels, and to serve as a subchondral substrate for tissue-engineered osteochondral constructs. Methods used to manipulate the structure and performance of bioactive glass in these tissue engineering applications are analyzed. PMID:21421084

Rahaman, Mohamed N.; Day, Delbert E.; Bal, B. Sonny; Fu, Qiang; Jung, Steven B.; Bonewald, Lynda F.; Tomsia, Antoni P.

2011-01-01

280

Density of Vibrational States of a Hyperquenched Glass  

SciTech Connect

The vibrational density of states of a hyperquenched and an annealed glass has been measured using nuclear inelastic scattering. The hyperquenched sample shows a higher number of vibrational states in the low-energy region with respect to the annealed glass. It reveals, however, lower density and sound velocity and, therefore, smaller Debye energy. After rescaling the energy axes in Debye energy units and area renormalization, the density of states of both samples becomes identical. Thus, the effect of quenching is described by the transformation of the continuous medium.

Monaco, A.; Chumakov, A.I.; Monaco, G.; Crichton, W.A.; Rueffer, R. [European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble (France); Yue, Y.-Z. [Section of Chemistry, Aalborg University, DK-9000 Aalborg (Denmark); Comez, L.; Fioretto, D. [INFM CRS-SOFT, c/o Universita di Roma 'La Sapienza', P.A. Moro 2, I-00185 Rome (Italy); Dipartimento di Fisica, Universita di Perugia, I-06123 Perugia (Italy)

2006-05-26

281

Atomic dynamics of tin nanoparticles embedded into porous glass  

SciTech Connect

The method of resonant nuclear inelastic absorption of synchrotron radiation has been used to study the phonon spectrum for tin nanoparticles (with a natural isotope mixture) embedded into a porous glassy (silica) matrix with an average pore diameter of 7 nm in comparison to the analogous spectrum of bulk tin enriched with {sup 119}Sn isotope. Differences between the spectra have been observed, which are related to both the dimensional effects and specific structural features of the porous glass-tin nanocomposite. Peculiarities in the dynamics of tin atoms embedded into nanopores of glass are interpreted in terms of a qualitative model of the nanocomposite structure.

Parshin, P. P.; Zemlyanov, M. G., E-mail: zeml@isssph.kiae.ru; Panova, G. Kh.; Shikov, A. A. [Russian Research Centre Kurchatov Institute (Russian Federation); Kumzerov, Yu. A.; Naberezhnov, A. A. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Sergueev, I.; Crichton, W. [European Synchrotron Radiation Facility (France); Chumakov, A. I. [Russian Research Centre Kurchatov Institute (Russian Federation); Rueffer, R. [European Synchrotron Radiation Facility (France)

2012-03-15

282

Mixed polyanion glass cathodes: Iron phosphate vanadate glasses  

SciTech Connect

Mixed polyanion (MP) glasses have been investigated for use as cathodes in lithium ion batteries. MP glass cathodes are similar in composition to theoretically promising crystalline polyanionic (CP) cathodes (e.g., lithium cobalt phosphate, lithium manganese silicate), but with proper polyanion substitution, they can be designed to overcome the key shortcomings of CP cathodes, such as poor electrical conductivity and irreversible phase changes. Iron phosphate/vanadate glasses were chosen as a first demonstration of the MP glass concept. Polyanion substitution with vanadate was shown to improve the intercalation capacity of an iron phosphate glass from almost zero to full theoretical capacity. In addition, the MP glass cathodes also exhibited an unexpected second high-capacity electrochemical reaction. X-ray absorption near-edge structure (XANES) and x-ray diffraction (XRD) of cathodes from cells having different states of charge suggested that this second electrochemical reaction is a glass-state conversion reaction. With a first demonstration established, MP glass materials utilizing an intercalation and/or glass-state conversion reaction are promising candidates for future high-energy cathode research.

Kercher, Andrew K [ORNL; Ramey, Joanne Oxendine [ORNL; Carroll, Kyler J [Massachusetts Institute of Technology (MIT); Kiggans Jr, James O [ORNL; Veith, Gabriel M [ORNL; Meisner, Roberta [Oak Ridge National Laboratory (ORNL); Boatner, Lynn A [ORNL; Dudney, Nancy J [ORNL

2014-01-01

283

Fracture mechanics of cellular glass  

NASA Technical Reports Server (NTRS)

The fracture mechanics of cellular glasses (for the structural substrate of mirrored glass for solar concentrator reflecting panels) are discussed. Commercial and developmental cellular glasses were tested and analyzed using standard testing techniques and models developed from linear fracture mechanics. Two models describing the fracture behavior of these materials were developed. Slow crack growth behavior in cellular glass was found to be more complex than that encountered in dense glasses or ceramics. The crack velocity was found to be strongly dependent upon water vapor transport to the tip of the moving crack. The existence of a static fatigue limit was not conclusively established, however, it is speculated that slow crack growth behavior in Region 1 may be slower, by orders of magnitude, than that found in dense glasses. Previously announced in STAR as N82-11209

Zwissler, J. G.; Adams, M. A.

1983-01-01

284

Fracture mechanics of cellular glass  

NASA Technical Reports Server (NTRS)

The fracture mechanics of cellular glasses (for the structural substrate of mirrored glass for solr concentrator reflecting panels) are discussed. Commercial and developmental cellular glasses were tested and analyzed using standard testing techniques and models developed from linear fracture mechanics. Two models describing the fracture behavior of these materials were developed. Slow crack growth behavior in cellular glass was found to be more complex than that encountered in dense glasses or ceramics. The crack velocity was found to be strongly dependent upon water vapor transport to the tip of the moving crack. The existence of a static fatigue limit was not conclusively established, however, it is speculated that slow crack growth behavior in Region 1 may be slower, by orders of magnitude, than that found in dense glasses.

Zwissler, J. G.; Adams, M. A.

1981-01-01

285

Method for heating a glass sheet  

DOEpatents

A method for heating a glass sheet includes the steps of heating a glass sheet to a first predetermined temperature and applying microwave energy to the glass sheet to heat the glass sheet to at least a second predetermined temperature to allow the glass sheet to be formed. 5 figs.

Boaz, P.T.

1998-07-21

286

Method for heating a glass sheet  

DOEpatents

A method for heating a glass sheet includes the steps of heating a glass sheet to a first predetermined temperature and applying microwave energy to the glass sheet to heat the glass sheet to at least a second predetermined temperature to allow the glass sheet to be formed.

Boaz, Premakaran Tucker (Livonia, MI)

1998-01-01

287

Silver Valence and Local Environments in Borosilicate and Calcium Aluminoborate Waste Glasses as determined from X-ray Absorption Spectroscopy  

SciTech Connect

Silver K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data were collected and analyzed to characterize silver (Ag) environments in borosilicate and Ca-aluminoborate glass formulations developed as potential candidates for the immobilization of certain nuclear wastes. Silver is found in some nuclear waste streams and must be encapsulated in glass during waste vitrification processes. A related concern deals with phase separation within these glasses and whether colloidal silver would be present in the glass melt, which could present processing issues, or in the waste glass product. Characterization of the silver environments provides useful information for optimizing the silver incorporation ability of such glasses. Data were also gathered on four crystalline standards: Ag-foil, Ag{sub 2}O, argentojarosite (AgFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}), and AgO. XANES data indicate Ag{sup +} as the dominant species in the glasses. XANES and EXAFS data show that the average Ag environment in the Ca-aluminoborate glass is different compared with those in the two borosilicate glasses investigated. EXAFS analyses show that Ag in the borosilicate glasses is coordinated by two oxygens in a similar environment to that in crystalline Ag{sub 2}O, except that the associated Ag-O distances are approximately 0.10 Angstroms longer in the glass. Silver in the Ca-aluminoborate glass may be within one highly disordered site, or possibly, several different sites, where the average Ag-O distance, coordination number, and Debye-Waller factor are larger than those determined for the borosilicate glasses. Despite their relatively high silver contents, there is no evidence from XANES or EXAFS of colloidal silver in the glasses investigated.

McKeown,D.; Gan, H.; Pegg, I.

2005-01-01

288

Glass rupture disk  

DOEpatents

A frangible rupture disk and mounting apparatus for use in blocking fluid flow, generally in a fluid conducting conduit such as a well casing, a well tubing string or other conduits within subterranean boreholes. The disk can also be utilized in above-surface pipes or tanks where temporary and controllable fluid blockage is required. The frangible rupture disk is made from a pre-stressed glass with controllable rupture properties wherein the strength distribution has a standard deviation less than approximately 5% from the mean strength. The frangible rupture disk has controllable operating pressures and rupture pressures.

Glass, S. Jill (Albuquerque, NM); Nicolaysen, Scott D. (Albuquerque, NM); Beauchamp, Edwin K. (Albuquerque, NM)

2002-01-01

289

Combined Experimental and Computational Approach to Predict the Glass-Water Reaction  

SciTech Connect

The use of mineral and glass dissolution rates measured in laboratory experiments to predict the weathering of primary minerals and volcanic and nuclear waste glasses in field studies requires the construction of rate models that accurately describe the weathering process over geologic timescales. Additionally, the need to model the long-term behavior of nuclear waste glass for the purpose of estimating radionuclide release rates requires that rate models be validated with long-term experiments. Several long-term test methods have been developed to accelerate the glass-water reaction [drip test, vapor hydration test, product consistency test B, and pressurized unsaturated flow (PUF)], thereby reducing the duration required to evaluate long-term performance. Currently, the PUF test is the only method that mimics the unsaturated hydraulic properties expected in a subsurface disposal facility and simultaneously monitors the glass-water reaction. PUF tests are being conducted to accelerate the weathering of glass and validate the model parameters being used to predict long-term glass behavior. A one-dimensional reactive chemical transport simulation of glass dissolution and secondary phase formation during a 1.5-year-long PUF experiment was conducted with the Subsurface Transport Over Reactive Multiphases (STORM) code. Results show that parameterization of the computer model by combining direct bench scale laboratory measurements and thermodynamic data provides an integrated approach to predicting glass behavior over the length of the experiment. Over the 1.5-year-long test duration, the rate decreased from 0.2 to 0.01 g/(m2 day) based on B release for low-activity waste glass LAWA44. The observed decrease is approximately two orders of magnitude higher than the decrease observed under static conditions with the SON68 glass (estimated to be a decrease by four orders of magnitude) and suggests that the gel-layer properties are less protective under these dynamic conditions.

Pierce, Eric M.; Bacon, Diana H.

2011-10-01

290

POROUS WALL, HOLLOW GLASS MICROSPHERES  

SciTech Connect

Hollow Glass Microspheres (HGM) is not a new technology. All one has to do is go to the internet and Google{trademark} HGM. Anyone can buy HGM and they have a wide variety of uses. HGM are usually between 1 to 100 microns in diameter, although their size can range from 100 nanometers to 5 millimeters in diameter. HGM are used as lightweight filler in composite materials such as syntactic foam and lightweight concrete. In 1968 a patent was issued to W. Beck of the 3M{trademark} Company for 'Glass Bubbles Prepared by Reheating Solid Glass Particles'. In 1983 P. Howell was issued a patent for 'Glass Bubbles of Increased Collapse Strength' and in 1988 H. Marshall was issued a patent for 'Glass Microbubbles'. Now Google{trademark}, Porous Wall, Hollow Glass Microspheres (PW-HGMs), the key words here are Porous Wall. Almost every article has its beginning with the research done at the Savannah River National Laboratory (SRNL). The Savannah River Site (SRS) where SRNL is located has a long and successful history of working with hydrogen and its isotopes for national security, energy, waste management and environmental remediation applications. This includes more than 30 years of experience developing, processing, and implementing special ceramics, including glasses for a variety of Department of Energy (DOE) missions. In the case of glasses, SRS and SRNL have been involved in both the science and engineering of vitreous or glass based systems. As a part of this glass experience and expertise, SRNL has developed a number of niches in the glass arena, one of which is the development of porous glass systems for a variety of applications. These porous glass systems include sol gel glasses, which include both xerogels and aerogels, as well as phase separated glass compositions, that can be subsequently treated to produce another unique type of porosity within the glass forms. The porous glasses can increase the surface area compared to 'normal glasses of a 1 to 2 order of magnitude, which can result in unique properties in areas such as hydrogen storage, gas transport, gas separations and purifications, sensors, global warming applications, new drug delivery systems and so on. One of the most interesting porous glass products that SRNL has developed and patented is Porous Wall, Hollow Glass Microspheres (PW-HGMs) that are being studied for many different applications. The European Patent Office (EPO) just recently notified SRS that the continuation-in-part patent application for the PW-HGMs has been accepted. The original patent, which was granted by the EPO on June 2, 2010, was validated in France, Germany and the United Kingdom. The microspheres produced are generally in the range of 2 to 100 microns, with a 1 to 2 micron wall. What makes the SRNL microspheres unique from all others is that the team in Figure 1 has found a way to induce and control porosity through the thin walls on a scale of 100 to 3000 {angstrom}. This is what makes the SRNL HW-HGMs one-of-a-kind, and is responsible for many of their unique properties and potential for various applications, including those in tritium storage, gas separations, H-storage for vehicles, and even a variety of new medical applications in the areas of drug delivery and MRI contrast agents. SRNL Hollow Glass Microspheres, and subsequent, Porous Wall, Hollow Glass Microspheres are fabricated using a flame former apparatus. Figure 2 is a schematic of the apparatus.

Sexton, W.

2012-06-30

291

Solution of naturally-ocurring glasses in the geological environment  

NASA Technical Reports Server (NTRS)

As part of a study to investigate the feasibility of putting nuclear wastes in glass containers and burying them on land or dumping them in the ocean, the amount of solution experience by naturally occurring glasses from two land sites and thirty-four deep sea sites was studied. The glasses are microtektites from three strewn fields and from the Zhamanshin impact crater. The microtektites range in age from 0.7 to 35 m.y. and have a wide range in composition. The weight percent SiO2, for example, ranges from 44.8 to 81.7. Although several criteria for determining the amount of solution were considered, most of the conclusions are based on two criteria: (1) width of cracks, and (2) elevation of silica rich inclusions above the adjacent microtektite surface. All the measurements were made on scanning electron microscope photomicrographs of the microtektites.

Glass, B. P.

1982-01-01

292

CHEMICAL ANALYSIS OF SIMULATED HIGH LEVEL WASTE GLASSES TO SUPPORT SULFATE SOLUBILITY MODELING  

SciTech Connect

The U.S. Department of Energy (DOE), Office of Environmental Management (EM) is sponsoring an international, collaborative project to develop a fundamental model for sulfate solubility in nuclear waste glass. The solubility of sulfate has a significant impact on the achievable waste loading for nuclear waste forms both within the DOE complex and to some extent at U.K. sites. The development of enhanced borosilicate glass compositions with improved sulfate solubility will allow for higher waste loadings and accelerated cleanup missions. Much of the previous work on improving sulfate retention in waste glasses has been done on an empirical basis, making it difficult to apply the findings to future waste compositions despite the large number of glass systems studied. A more fundamental, rather than empirical, model of sulfate solubility in glass, under development at Sheffield Hallam University (SHU), could provide a solution to the issues of sulfate solubility. The model uses the normalized cation field strength index as a function of glass composition to predict sulfate capacity, and has shown early success for some glass systems. The objective of the current scope is to mature the sulfate solubility model to the point where it can be used to guide glass composition development for DOE waste vitrification efforts, allowing for enhanced waste loadings and waste throughput. A series of targeted glass compositions was selected to resolve data gaps in the current model. SHU fabricated these glasses and sent samples to the Savannah River National Laboratory (SRNL) for chemical composition analysis. SHU will use the resulting data to enhance the sulfate solubility model and resolve any deficiencies. In this report, SRNL provides chemical analyses for simulated waste glasses fabricated SHU in support of sulfate solubility model development. A review of the measured compositions revealed that there are issues with the B{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} concentrations missing their targeted values by a significant amount for several of the study glasses. SHU is reviewing the fabrication of these glasses and the chemicals used in batching them to identify the source of these issues. The measured sulfate concentrations were all below their targeted values. This is expected, as the targeted concentrations likely exceeded the solubility limit for sulfate in these glass compositions. Some volatilization of sulfate may also have occurred during fabrication of the glasses. Measurements of the other oxides in the study glasses were reasonably close to their targeted values

Fox, K.; Marra, J.

2014-08-14

293

Mechanical failure and glass transition in metallic glasses  

SciTech Connect

The current majority view on the phenomenon of mechanical failure in metallic glasses appears to be that it is caused by the activity of some structural defects, such as free-volumes or shear transformation zones, and the concentration of such defects is small, only of the order of 1%. However, the recent results compel us to revise this view. Through molecular dynamics simulation it has been shown that mechanical failure is the stress-induced glass transition. According to our theory the concentration of the liquid-like sites (defects) is well over 20% at the glass transition. We suggest that the defect concentration in metallic glasses is actually very high, and percolation of such defects causes atomic avalanche and mechanical failure. In this article we discuss the glass transition, mechanical failure and viscosity from such a point of view.

Egami, Takeshi [ORNL

2011-01-01

294

ConcepTest: Glass-Rock Analogy  

NSDL National Science Digital Library

Glass is made by melting silica-rich sand. The molten glass is then formed into shapes as it cools. Glass making could be seen as an analog for the formation of a. igneous rock b. metamorphic rock c. sedimentary ...

295

Aspects of the mechanics of metallic glasses  

E-print Network

Metallic glasses are amorphous materials that possess unique mechanical properties, such as high tensile strengths and good fracture toughnesses. Also, since they are amorphous, metallic glasses exhibit a glass transition, ...

Henann, David Lee

2011-01-01

296

Iodine valence and local environments in borosilicate waste glasses using X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

The radioisotope 129I, a fission product in spent nuclear fuel, has a long half-life, and can be highly mobile in the environment. Iodine K-edge X-ray absorption spectra were collected to characterize the iodine valence and coordination environment in simulated Hanford low activity waste glasses. Both iodine XANES and EXAFS data for eleven borosilicate glasses indicate iodide-like environments within the glass structure, where I- has Na or Li nearest-neighbors, and where the nearest-neighbor cation-type correlates to the most common network-modifying cation in the glass. This is further supported by the systematic increase of iodine incorporation with the combined Na2O + Li2O content in the glass. EXAFS analyses determined I-Na distances near 3.04 Å with coordination numbers near 4.0 and I-Li distances near 2.80 Å with coordination numbers near 3.0. I-Na environments determined for the glasses are similar to the tetrahedral INa4 coordination found in NaI-sodalite. These weakly bound iodine-alkali configurations may be the only pathways for iodine to be retained in the glass. These environments may be precursors to NaI-sodalite crystallization in Na-rich glass. Iodine also shows distinct differences from chlorine in terms of the preferred sites in the glass structure.

McKeown, David A.; Muller, Isabelle S.; Pegg, Ian L.

2015-01-01

297

Refractory Glass Seals for SOFC  

SciTech Connect

One of the critical challenges facing planar solid oxide fuel cell (SOFC) technology is the need for reliable sealing technology. Seals must exhibit long-term stability and mechanical integrity in the high temperature SOFC environment during normal and transient operation. Several different approaches for sealing SOFC stacks are under development, including glass or glass-ceramic seals, metallic brazes, and compressive seals. Among glass seals, rigid glass-ceramics, self-healing glass, and composite glass approaches have been investigated under the SECA Core Technology Program. The U.S. Department of Energy's Pacific Northwest National Laboratory (PNNL) has developed the refractory glass approach in light of the fact that higher sealing temperatures (e.g., 930-1000 degrees C) may enhance the ultimate in-service bulk strength and electrical conductivity of contact materials, as well as the bonding strength between contact materials and adjacent SOFC components, such as interconnect coatings and electrodes. This report summarizes the thermal, chemical, mechanical, and electrical properties of the refractory sealing glass.

Chou, Y. S.; Stevenson, Jeffry W.

2011-07-01

298

Colorimetry in the glass industry  

Microsoft Academic Search

Recent knowledge of the glassy state has enabled the theories of modern colour chemistry to be applied to glass, and developments in colorimetric technique have put the design and performance of coloured glasses on a quantitative basis. The methods of colour measurement particularly suited to transparent media are described, together with rapid approximate methods of calculation. The properties of the

J G Holmes

1947-01-01

299

Method of determining glass durability  

DOEpatents

A process is described for determining one or more leachate concentrations of one or more components of a glass composition in an aqueous solution of the glass composition by identifying the components of the glass composition, including associated oxides, determining a preliminary glass dissolution estimator, {Delta}G{sub p}, based upon the free energies of hydration for the component reactant species, determining an accelerated glass dissolution function, {Delta}G{sub a}, based upon the free energy associated with weak acid dissociation, {Delta}G{sub a}{sup WA}, and accelerated matrix dissolution at high pH, {Delta}G{sub a}{sup SB} associated with solution strong base formation, and determining a final hydration free energy, {Delta}G{sub f}. This final hydration free energy is then used to determine leachate concentrations for elements of interest using a regression analysis and the formula log{sub 10}(N C{sub i}(g/L))=a{sub i} + b{sub i}{Delta}G{sub f}. The present invention also includes a method to determine whether a particular glass to be produced will be homogeneous or phase separated. The present invention is also directed to methods of monitoring and controlling processes for making glass using these determinations to modify the feedstock materials until a desired glass durability and homogeneity is obtained. 4 figs.

Jantzen, C.M.; Pickett, J.B.; Brown, K.G.; Edwards, T.B.

1998-12-08

300

Method of determining glass durability  

DOEpatents

A process for determining one or more leachate concentrations of one or more components of a glass composition in an aqueous solution of the glass composition by identifying the components of the glass composition, including associated oxides, determining a preliminary glass dissolution estimator, .DELTA.G.sub.p, based upon the free energies of hydration for the component reactant species, determining an accelerated glass dissolution function, .DELTA.G.sub.a, based upon the free energy associated with weak acid dissociation, .DELTA.G.sub.a.sup.WA, and accelerated matrix dissolution at high pH, .DELTA.G.sub.a.sup.SB associated with solution strong base formation, and determining a final hydration free energy, .DELTA.G.sub.f. This final hydration free energy is then used to determine leachate concentrations for elements of interest using a regression analysis and the formula log.sub.10 (N C.sub.i (g/L))=a.sub.i +b.sub.i .DELTA.G.sub.f. The present invention also includes a method to determine whether a particular glass to be produced will be homogeneous or phase separated. The present invention is also directed to methods of monitoring and controlling processes for making glass using these determinations to modify the feedstock materials until a desired glass durability and homogeneity is obtained.

Jantzen, Carol Maryanne (Aiken, SC); Pickett, John Butler (Aiken, SC); Brown, Kevin George (Augusta, GA); Edwards, Thomas Barry (Aiken, SC)

1998-01-01

301

Making a Better Beer Glass.  

ERIC Educational Resources Information Center

A class activity is detailed in which alternative designs for glasses are examined. The goal is to design a glass which is built tilted, so that beer can be poured in without creating a foam problem. The activity is viewed as one leading to interesting questions. (MP)

Hoffer, Alan R.

1982-01-01

302

Metallic glasses as structural materials  

Microsoft Academic Search

The potential of metallic glasses as structural materials is assessed. A wide-ranging comparison with conventional engineering materials shows metallic glasses to be restricted to niche applications, but with outstanding properties awaiting wider application, for example in micro electro-mechanical systems devices.

M. F. Ashby; A. L. Greer

2006-01-01

303

Radiation Effects in Nuclear Waste Materials  

SciTech Connect

The objective of this project is to develop a fundamental understanding of radiation effects in glasses and ceramics, as well as the influence of solid-state radiation effects on aqueous dissolution kinetics, which may impact the performance of nuclear waste forms and stabilized nuclear materials.

William j. Weber; Lumin Wang; Jonathan Icenhower

2004-07-09

304

Glass Nanofiber Fabrication and Devices  

NASA Astrophysics Data System (ADS)

We have integrated electric field assisted spinning (electrospinning) of polymeric materials with photolithography for the fabrication of glass nanostructures. We incorporated spin on glass (SOG) dielectric coating with poly-vinyl-pyrrolidone (PVP) and spun this solution over trenches etched in silicon. A calcination eliminated the PVP polymer from these fibers, while cross-linking the SOG, leaving silica glass fibers with diameters as small as 70 nm. We demonstrated the operation of these fibers as nanomechanical oscillators. We also spun heat depolymerizable polycarbonate (HDPC) fibers over silicon trenches. These fibers were coated with glass by chemical vapor deposition or sputtering, followed by thermal elimination of the polymer core. This yielded suspended glass channels of elliptical cross sections, with inner major and minor axes as small as 75 and 50 nm. These nanochannels offer a low background option for doing fluorescence detection, as demonstrated by single molecule detection, using a confocal microscope, of cellulase enzymes in these channels.

Verbridge, Scott; Edel, Joshua

2005-03-01

305

Nanophase Glass Ceramics for Capacitive Energy Storage.  

E-print Network

??Glass ceramics are candidate dielectric materials for high energy storage capacitors. Since energy density depends primarily on dielectric permittivity and breakdown strength, glass ceramics with… (more)

Rangarajan, Badri

2009-01-01

306

Product consistency testing of West Valley Compositional Variation Glasses  

SciTech Connect

Nuclear waste glass produced by the West Valley Demonstration Project (WVDP) must meet the requirements of the Waste Acceptance Preliminary Specification (WAPS) as developed by the US Department of Energy (DOE). To assist WVDP in complying with WAPS, the Materials Characterization Center (MCC) at Pacific Northwest Laboratory (PNL) used the Product Consistency Test (PCT) to evaluate 44 West Valley glasses that had previously been tested in FY 1987 and FY 1988. This report summarizes the results of the PCTs. The glasses tested, which were fabricated as sets of Compositional Variation Glasses for studies performed by the West Valley Support Task (WVST) at PNL during FY 1987 and FY 1988, were doped with Th and U and were variations of West Valley reference glasses. In addition, Approved Reference Material-1 (ARM-1) was used as a test standard (ARM-1 is supplied by the MCC). The PCT was originated at Westinghouse Savannah River Company (WSRC) by C. M. Jantzen and N. R. Bibler (Jantzen and Bibler 1989). The test is a seven-day modified MCC-3 test that uses crushed glass in the size range -100 +200 mesh with deionized water in a Teflon container. There is no agitation during the PCT, and no attempt to include CO{sub 2} from the test environment. Based on B and Li release, the glasses performed about the same as in previous modified MCC-3 testing performed in FY 1987 and FY 1988 (Reimus et al. 1988). The modified MCC-3 tests performed by Reimus et al. were similar to the PCT containers and the exclusion of CO{sub 2} from the tests.

Olson, K.M.; Marschman, S.C.; Piepel, G.F.; Whiting, G.K.

1994-11-01

307

Silicate glass alteration enhanced by iron: origin and long-term implications.  

PubMed

Silicate glasses are used as containment matrices for deep geological disposal of nuclear waste arising from spent fuel reprocessing. Understanding the dissolution mechanisms of glasses in contact with iron, an element present in large amounts in the immediate environment (overpack, claystone, etc.) would be a major breakthrough toward predicting radionuclide release in the geosphere after disposal. Two different reacted glass-iron interfaces-a short-term nuclear system and a long-term archeological system-were examined using a multiscale and multianalytical approach including, for the first time on samples of this type, STXM under synchrotron radiation. Comparisons revealed remarkable similarities between the two systems and shed light on Fe-Si interactions, including migration of iron within a porous gel layer and precipitation of Fe-silicates that locally increase short-term glass alteration and are sustainable over the long-term. PMID:23237387

Michelin, A; Burger, E; Rebiscoul, D; Neff, D; Bruguier, F; Drouet, E; Dillmann, P; Gin, S

2013-01-15

308

Structure, surface reactivity and physico-chemical degradation of fluoride containing phospho-silicate glasses  

SciTech Connect

We report on the structure, apatite-forming ability and physicochemical degradation of glasses along fluorapatite [FA; Ca5(PO4)3F] - diopside (Di; CaMgSi2O6) join. A series of glasses with varying FA/Di ratio have been synthesised by melt-quenching technique. The amorphous glasses could be obtained only for compositions up to 40 wt.% of FA. The detailed structural analysis of glasses has been made by infra-red spectroscopy (FTIR), Raman spectroscopy and magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR). Silicon was predominantly present as Q2 (Si) species while phosphorus was found in orthophosphate type environment in all the investigated glasses. The apatite forming ability of glasses was investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1 h – 28 days. An extensive precipitation of calcite (CaCO3) after immersion in SBF was found in all the glasses which considerably masked the formation of hydroxyapatite [HA; Ca5(PO4)3OH] as depicted by X-ray diffraction (XRD) and FTIR. The possible mechanism favouring formation of calcite instead of HA has been explained on the basis of experimental results obtained for structure of glasses, leaching profile of glass powders in SBF solution and pH variation in SBF solution. Further, physico-chemical degradation of glasses has been studied in accordance with ISO 10993-14 “Biological evaluation of medical devices – Part 14: Identification and quantification of degradation products from ceramics” in Tris HCl and citric acid buffer. All the FA containing glasses exhibited a weight gain (instead of weight loss) after immersion in citric acid buffer due to the formation of different crystalline products.

Kansal, Ishu; Goel, Ashutosh; Tulyaganov, Dilshat U.; Santos, Luis F.; Ferreira, Jose M.

2011-03-28

309

Thermo-physical and structural studies of sodium zinc borovanadate glasses in the region of high concentration of modifier oxides  

SciTech Connect

Highlights: ? Highly modified sodium zinc borovanadate glasses. ? Structural model for borovanadate glasses. ? Network forming tendency of ZnO in borovanadate glasses. ? Fragility can be limited to NBO concentration in borovanadate glasses. -- Abstract: This paper reports investigation of Na{sub 2}O and ZnO modified borovanadate glasses in the highly modified regime of compositions. These glasses have been prepared by microwave route. Ultraviolet (UV) and visible, infrared (IR), Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) and Electron Paramagnetic Resonance (EPR) spectroscopies have been used to characterize the speciation in the glasses. Together with the variation of properties such as molar volume and glass transition temperatures, spectroscopic data indicate that at high levels of modification, ZnO tends to behave like network former. It is proposed that the observed variation of all the properties can be reasonably well understood with a structural model. The model considers that the modification and speciation in glasses are strongly determined by the hierarchy of group electronegativities. Further, it is proposed that the width of the transitions of glasses obtained under same condition reflects the fragility of the glasses. An empirical expression has been suggested to quantify fragility on the basis of width of the transition regions.

Chethana, B.K. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012 (India)] [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012 (India); Reddy, C. Narayana [Maharani's Science College for Women, Bangalore 560 001 (India)] [Maharani's Science College for Women, Bangalore 560 001 (India); Rao, K.J., E-mail: kalyajrao@yahoo.co.in [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012 (India)

2012-07-15

310

Effect of tin on the relationship between composition, structure, and properties of soda-lime-silicate glasses  

NASA Astrophysics Data System (ADS)

The effect of tin on the properties of soda-lime-silicate glass was investigated using laboratory and commercial glasses. The commercial materials were float glasses, while the model glasses with nominal soda-lime-silicate commercial compositions were synthesized in the laboratory with tin concentrations ranging from 0--3 mol%. In one set of the modeled glasses, melt processing was used to drive the tin into the reduced state. Mossbauer spectroscopy was used to determine the presence and relative amounts of Sn2+ and Sn4+ in the glasses. The glasses were also examined using nuclear magnetic resonance (NMR) to gain insight into the effect of substituting tin for sodium on the number of silica Q4 species present in the glass structure. Dilatometry experiments revealed the effects of tin on the coefficient of thermal expansion, dilatometric softening temperature, and glass transition temperature. Beam-bending viscosity experiments were used to measure the viscosity as a function of tin, and from the viscosity curves, strain and annealing temperatures were determined. Sonic resonance, ultrasonic pulse, and nanoindentation experiments were performed to determine the role of tin on elastic modulus of the glass. The results of these experiments, along with the NMR and Mossbauer experiments, suggested that the substitution of tin for sodium results in an increase in the network connectivity of the glass structure. This increased network connectivity correlated with an increased in the ratio of Sn 4+/Sn2+ suggesting that Sn4+ plays a direct role in cross-linking the silicate structure.

Krohn, Matthew H.

311

Energetics of glass fragmentation: Experiments on synthetic and natural glasses  

NASA Astrophysics Data System (ADS)

Natural silicate glasses are an essential component of many volcanic rock types including coherent and pyroclastic rocks; they span a wide range of compositions, occur in diverse environments, and form under a variety of pressure-temperature conditions. In subsurface volcanic environments (e.g., conduits and feeders), melts intersect the thermodynamically defined glass transition temperature to form glasses at elevated confining pressures and under differential stresses. We present a series of room temperature experiments designed to explore the fundamental mechanical and fragmentation behavior of natural (obsidian) and synthetic glasses (Pyrex™) under confining pressures of 0.1-100 MPa. In each experiment, glass cores are driven to brittle failure under compressive triaxial stress. Analysis of the load-displacement response curves is used to quantify the storage of energy in samples prior to failure, the (brittle) release of elastic energy at failure, and the residual energy stored in the post-failure material. We then establish a relationship between the energy density within the sample at failure and the grain-size distributions (D-values) of the experimental products. The relationship between D-values and energy density for compressive fragmentation is significantly different from relationships established by previous workers for decompressive fragmentation. Compressive fragmentation is found to have lower fragmentation efficiency than fragmentation through decompression (i.e., a smaller change in D-value with increasing energy density). We further show that the stress storage capacity of natural glasses can be enhanced (approaching synthetic glasses) through heat treatment.

Kolzenburg, S.; Russell, J. K.; Kennedy, L. A.

2013-11-01

312

Database and Interim Glass Property Models for Hanford HLW Glasses  

SciTech Connect

The purpose of this report is to provide a methodology for an increase in the efficiency and a decrease in the cost of vitrifying high-level waste (HLW) by optimizing HLW glass formulation. This methodology consists in collecting and generating a database of glass properties that determine HLW glass processability and acceptability and relating these properties to glass composition. The report explains how the property-composition models are developed, fitted to data, used for glass formulation optimization, and continuously updated in response to changes in HLW composition estimates and changes in glass processing technology. Further, the report reviews the glass property-composition literature data and presents their preliminary critical evaluation and screening. Finally the report provides interim property-composition models for melt viscosity, for liquidus temperature (with spinel and zircon primary crystalline phases), and for the product consistency test normalized releases of B, Na, and Li. Models were fitted to a subset of the screened database deemed most relevant for the current HLW composition region.

Hrma, Pavel R.; Piepel, Gregory F.; Vienna, John D.; Cooley, Scott K.; Kim, Dong-Sang; Russell, Renee L.

2001-07-24

313

Structure of zinc polyphosphate glasses studied by two-dimensional solid and liquid state NMR  

NASA Astrophysics Data System (ADS)

A series of 10 binary zinc phosphate glasses with composition xZnO+(1- x)P 2O 5 (0.35? x?0.80) is studied by means of two-dimensional (2D) solid and liquid state 31P nuclear magnetic resonance (NMR). Double quantum (DQ) filtering method is used to probe 31P- 31P connectivities through dipolar interactions in solid samples. Similar information is obtained using the correlation spectroscopy (COSY) experiment in solution. It is shown that these 2D NMR methods are capable of scrutinizing the evolution of glass structure versus x with improved precision. Varied relative concentrations of dimers, short or long branched chains and ring structures are found in glasses with different composition. Average chain length in the glasses is determined from the NMR results and compared with HPLC data and theoretical predictions. Finally, the evolution of glass structure is studied as a function of the synthesis temperature.

Wiench, J. W.; Tischendorf, B.; Otaigbe, J. U.; Pruski, M.

2002-01-01

314

Simulation of cooling and solidification of three-dimensional bulk borosilicate glass: effect of structural relaxations  

SciTech Connect

Abstract The modeling of the viscoelastic stress evolution and specific volume relaxation of a bulky glass cast is presented in this article and is applied to the experimental cooling process of an inactive nuclear waste vitrification process. The concerned borosilicate glass is solidified and cooled down to ambient temperature in a stainless steel canister, and the thermomechanical response of the package is simulated. There exists a deviant compression of the liquid core due to the large glass package compared to standard tempered glass plates. The stress load development of the glass cast is finally studied for different thermal load scenarios, where the cooling process parameters or the final cooldown rates were changed, and we found a great influence of the studied cooldown rates on the maximum stress buildup at ambient temperature.

Barth, N.; George, D.; Ahzi, Said; Remond, Y.; Joulaee, N.; Khaleel, Mohammad A.; Bouyer, F.

2014-02-28

315

Fabrication and characterization of MCC approved testing material - ATM-12 glass  

SciTech Connect

The Materials Characterization Center (MCC) Approved Testing Material ATM-12 is a borosilicate glass that incorporates elements typical of high-level waste (HLW) resulting from the reprocessing of commercial nuclear reactor fuels. The composition has been adjusted to match that predicted for HLW type 76-68 glass at an age of 300 y. Radioactive constituents contained in this glass include depleted uranium, {sup 99}Tc, {sup 237}Np, {sup 239}Pu, and {sup 241}Am. The glass was produced by the MCC at the Pacific Northwest Laboratory (PNL). ATM-12 glass ws produced from July to November of 1984 at the request of the Nevada Nuclear Waste Site Investigations (NNWSI) Program and is the third in a series of glasses produced for NNWSI. Most of the glass produced was in the form of cast bars; special castings and crushed material were also produced. Three kilograms of ATM-12 glass were produced from a feedstock melted in a nitrogen-atmosphere glove box at 1150{sup 0}C in a platinum crucible, and formed into stress-annealed rectangular bars and the special casting shapes requested by NNWSI. Bars of ATM-12 were nominally 1.9 x 1.9 x 10 cm, with an average mass of 111 g each. Nineteen bars and 37 special castings were made. ATM-12 glass has been provided to the NNWSI Program, in the form of bars, crushed powder and special castings. As of August 1985 approximately 590 g of ATM-12 is available for distribution. Requests for materials or services related to this glass should be directed to the Materials Characterization Center Program Office, PNL.

Wald, J.W.

1985-10-01

316

The role of test parameters on the kinetics and thermodynamics of glass leaching. [None  

SciTech Connect

The relative durabilities of nuclear waste, natural, and ancient glasses have been assessed by standard laboratory leach tests. Different test conditions result in different glass surface areas (SA), leachant volumes (V), and test durations (t). Leachate concentrations are known to be a parabolic function of the kinetic test parameter SAV/center dot/t. Based on durability experiments of glass monoliths at low (SAV)/center dot/ glass durability has been shown to be a logarithmic function of the thermodynamic hydration free energy, ..delta..G/sub hyd/. The thermodynamic hydration free energy, ..delta..G/sub hyd/, can be calculated from glass composition and solution pH. In the repository environment high effective glass surface areas to solution volume ratios may occur as a result of slow groundwater flow rates. The application of hydration thermodynamics to crushed glass, high (SAV)/center dot/t, durability tests has been demonstrated. The relative contributions of the kinetic test parameters, (SAV)/center dot/t, and the thermodynamic parameter, ..delta..G/sub hyd/, have been shown to define a plane in ..delta..G/sub hyd/-concentration-(SAV)/center dot/t space. At constant test conditions, e.g. constant (SAV/center dot/t, the intersection with this surface indicates that all /delta G//sub hyd/-concentration plots should have similar slopes and predict the same relative durabilities for various glasses as a function of glass composition. Using this approach, the durability of nuclear waste glasses has been interpolated to be -- 10/sup 6/ years and no less than 10/sup 3/ years. 28 refs., 24 figs.

Jantzen, C M

1988-01-01

317

Combined Experimental and Computational Approach to Predict the Glass-Water Reaction  

SciTech Connect

The use of mineral and glass dissolution rates measured in laboratory experiments to predict the weathering of primary minerals and volcanic and nuclear waste glasses in field studies requires the construction of rate models that accurately describe the weathering process over geologic time-scales. Additionally, the need to model the long-term behavior of nuclear waste glass for the purpose of estimating radionuclide release rates requires that rate models are validated with long-term experiments. Several long-term test methods have been developed to accelerate the glass-water reaction [drip test, vapor hydration test, product consistency test-B, and pressurized unsaturated flow (PUF)], thereby reducing the duration required to evaluate long-term performance. Currently, the PUF test is the only method that mimics the unsaturated hydraulic properties expected in a subsurface disposal facility and simultaneously monitors the glass-water reaction. PUF tests are being conducted to accelerate the weathering of glass and validate the model parameters being used to predict long-term glass behavior. A one-dimensional reactive chemical transport simulation of glass dissolution and secondary phase formation during a 1.5-year long PUF experiment was conducted with the subsurface transport over reactive multi-phases code. Results show that parameterization of the computer model by combining direct bench-scale laboratory measurements and thermodynamic data provides an integrated approach to predicting glass behavior over the length of the experiment. Over the 1.5-year long test duration, the rate decreased from 0.2 to 0.01 g/(m2 d) base on B release. The observed decrease is approximately two orders of magnitude higher than the decrease observed under static conditions with the SON68 glass (estimated to be a decrease by 4 orders of magnitude) and suggest the gel-layer properties are less protective under these dynamic conditions.

Pierce, Eric M [ORNL; Bacon, Diana [Pacific Northwest National Laboratory (PNNL)

2011-01-01

318

Changes in surface structure of sodium aluminoborosilicate glasses during aqueous corrosion analyzed by using NMR  

NASA Astrophysics Data System (ADS)

Aqueous corrosion tests were performed for aluminoborosilicate glasses with different Na contents at 90 °C for 20 days. Multi-nuclear solid-state nuclear magnetic resonance (NMR) techniques were employed to characterize the structures of the pristine and altered glasses. 11B magic-angle spinning (MAS) NMR spectra showed the same line shape for the pristine and altered glasses, indicating that B species such as BO3 and BO4 were released into the solution congruently with the same fraction during the static dissolution experiments. The reconstruction of Si on the glass surface as hydrated phases was confirmed by the 29Si MAS and 1H ?29Si cross-polarization magic-angle spinning NMR spectra of the altered glasses. 23Na MAS and triple-quantum magic-angle spinning NMR spectra showed that part of the Na released from pristine glasses was incorporated in the hydrated phases, which can be identified by a 23Na chemical shift at ?iso = - 3.3 ppm. The availability of these structural data by employing solid-state NMR techniques can provide a better understanding of the formation of the hydrated phases and the effect of dissolution behavior on the glass composition.

Ohkubo, Takahiro; Iwadate, Yasuhiko; Deguchi, Kenzo; Ohki, Shinobu; Shimizu, Tadashi

2015-02-01

319

Are gel-derived glasses different from ordinary glasses?  

NASA Technical Reports Server (NTRS)

A review is presented of some of the previously reported differences and similarities between comparable gel glasses (and gels) and ordinary glasses. In this regard, considerations are made with respect to such factors as structure, physical and thermal properties, and phase transformation behavior. A variety of silicate glass compositions are used for illustrative purposes. The discussion is roughly divided into two sections: low and high temperature behavior. At low temperatures one anticipates that differences between gel and conventional glasses will exist, but such dissimilarities are not expected to persist to high temperatures. However, experimental evidence is presented which indicates the perpetuation of such differences to very high temperatures. A partial resolution for this anomalous behavior is offered.

Weinberg, M. C.

1986-01-01

320

Glass microspheres for medical applications  

NASA Astrophysics Data System (ADS)

Radioactive dysprosium lithium borate glass microspheres have been developed as biodegradable radiation delivery vehicles for the radiation synovectomy treatment of rheumatoid arthritis. Once injected into a diseased joint, the microspheres deliver a potent dose of radiation to the diseased tissue, while a non-uniform chemical reaction converts the glass into an amorphous, porous, hydrated dysprosium phosphate reaction product. The non-radioactive, lithium-borate component is dissolved from the glass (up to 94% weight loss), while the radioactive 165Dy reacts with phosphate anions in the body fluids, and becomes "chemically" trapped in a solid, dysprosium phosphate reaction product that has the same size as the un-reacted glass microsphere. Ethylene diamine tetraacetate (EDTA) chelation therapy can be used to dissolve the dysprosium phosphate reaction product after the radiation delivery has subsided. The dysprosium phosphate reaction product, which formed in vivo in the joint of a Sprague-Dawley rat, was dissolved by EDTA chelation therapy in <1 week, without causing any detectable joint damage. The combination of dysprosium lithium borate glass microspheres and EDTA chelation therapy provides an unique "tool" for the medical community, which can deliver a large dose (>100 Gy) of localized beta radiation to a treatment site within the body, followed by complete biodegradability. The non-uniform reaction process is a desirable characteristic for a biodegradable radiation delivery vehicle, but it is also a novel material synthesis technique that can convert a glass to a highly porous materials with widely varying chemical composition by simple, low-temperature, glass/solution reaction. The reaction product formed by nonuniform reaction occupies the same volume as the un-reacted glass, and after drying for 1 h at 300°C, has a specific surface area of ?200 m2/g, a pore size of ?30 nm, and a nominal crushing strength of ?10 MPa. Finally, rhenium glass microspheres, composed of micron-sized, metallic rhenium particles dispersed within a magnesium alumino borate glass matrix were produced by sintering ReO2 powder and glass frit at 1050°C. A 50 mg injection of radioactive rhenium glass microspheres containing 3.7 GBq of 186Re and 8.5 GBq of 188Re could be used to deliver a 100 Gy dose to a cancerous tumor, while limiting the total body dose caused by rhenium dissolution to approximately 1 mGy.

Conzone, Samuel David

321

Recent developments in laser glasses  

SciTech Connect

The past decade has witnessed a proliferation of new glass-forming compositions including oxides, halides, oxyhalides, and chalcogenides. Many of these glasses are applicable to lasers and have greatly expanded the range of optical properties and spectroscopic parameters available to the laser designer. Our knowledge and understanding of many properties of interest for laser action - transparency, linear and nonlinear refractive indices, and damage threshold of the host glass and the absorption spectrum, radiative and nonradiative transition probabilities, fluorescence wavelength, stimulated emission cross section, and spectroscopic inhomogeneities of the lasing ion Nd/sup 3 +/ - are reviewed.

Weber, M.J.

1983-01-10

322

Glass Elasticity from Particle Trajectories  

NASA Astrophysics Data System (ADS)

Using positional data from video microscopy of a two-dimensional colloidal system and from simulations of hard disks, we determine the wave-vector-dependent elastic dispersion relations in glass. The emergence of rigidity based on the existence of a well defined displacement field in amorphous solids is demonstrated. Continuum elastic theory is recovered in the limit of long wavelengths which provides the glass elastic shear and bulk modulus as a function of temperature. The onset of a finite static shear modulus upon cooling marks the fluid-glass transition in an intuitive and unique way.

Klix, Christian L.; Ebert, Florian; Weysser, Fabian; Fuchs, Matthias; Maret, Georg; Keim, Peter

2012-10-01

323

Glass elasticity from particle trajectories.  

PubMed

Using positional data from video microscopy of a two-dimensional colloidal system and from simulations of hard disks, we determine the wave-vector-dependent elastic dispersion relations in glass. The emergence of rigidity based on the existence of a well defined displacement field in amorphous solids is demonstrated. Continuum elastic theory is recovered in the limit of long wavelengths which provides the glass elastic shear and bulk modulus as a function of temperature. The onset of a finite static shear modulus upon cooling marks the fluid-glass transition in an intuitive and unique way. PMID:23215226

Klix, Christian L; Ebert, Florian; Weysser, Fabian; Fuchs, Matthias; Maret, Georg; Keim, Peter

2012-10-26

324

Continuous Fibre Reinforced Glass and Glass-Ceramic Matrix Composites  

Microsoft Academic Search

Glass and glass-ceramic matrix composites with continuous fibre reinforcement are considered in this Chapter, covering aspects\\u000a of their fabrication, microstructural characterisation, properties and applications. The great variety of composite systems\\u000a developed during the last 30 years is discussed and their outstanding thermomechanical properties and high technological potential\\u000a are highlighted. These composites constitute a new family of high-temperature capability, lightweight structural

Aldo R. Boccaccini

325

Glass-glass transition during aging of a colloidal clay.  

PubMed

Colloidal suspensions are characterized by a variety of microscopic interactions, which generate unconventional phase diagrams encompassing fluid, gel and glassy states and offer the possibility to study new phase and/or state transitions. Among these, glass-glass transitions are rare to be found, especially at ambient conditions. Here, through a combination of dilution experiments, X-ray photon correlation spectroscopy, small angle X-ray scattering, rheological measurements and Monte Carlo simulations, we provide evidence of a spontaneous glass-glass transition in a colloidal clay. Two different glassy states are distinguished with evolving waiting time: a first one, dominated by long-range screened Coulombic repulsion (Wigner glass) and a second one, stabilized by orientational attractions (Disconnected House of Cards glass), occurring after a much longer time. These findings may have implications for heterogeneously charged systems out-of-equilibrium and for applications where a fine control of the local order and/or long term stability of the amorphous materials are required. PMID:24887086

Angelini, Roberta; Zaccarelli, Emanuela; de Melo Marques, Flavio Augusto; Sztucki, Michael; Fluerasu, Andrei; Ruocco, Giancarlo; Ruzicka, Barbara

2014-01-01

326

Glass-glass transition during aging of a colloidal clay  

NASA Astrophysics Data System (ADS)

Colloidal suspensions are characterized by a variety of microscopic interactions, which generate unconventional phase diagrams encompassing fluid, gel and glassy states and offer the possibility to study new phase and/or state transitions. Among these, glass-glass transitions are rare to be found, especially at ambient conditions. Here, through a combination of dilution experiments, X-ray photon correlation spectroscopy, small angle X-ray scattering, rheological measurements and Monte Carlo simulations, we provide evidence of a spontaneous glass-glass transition in a colloidal clay. Two different glassy states are distinguished with evolving waiting time: a first one, dominated by long-range screened Coulombic repulsion (Wigner glass) and a second one, stabilized by orientational attractions (Disconnected House of Cards glass), occurring after a much longer time. These findings may have implications for heterogeneously charged systems out-of-equilibrium and for applications where a fine control of the local order and/or long term stability of the amorphous materials are required.

Angelini, Roberta; Zaccarelli, Emanuela; de Melo Marques, Flavio Augusto; Sztucki, Michael; Fluerasu, Andrei; Ruocco, Giancarlo; Ruzicka, Barbara

2014-06-01

327

Stress Corrosion and Static Fatigue of Glass  

Microsoft Academic Search

Stress corrosion cracking of six glasses was studied using fracture mechanics techniques. Crack velocities in water were measured as a function of applied stress intensity factor and temperature, and apparent activation energies for crack mo- tion were obtained. Data were consistent with the universal fatigue curve for static fatigue of glass, which depended on glass composition. Of the glasses tested,

S. M. WIEDERHORN; L. H. BOLZ

1970-01-01

328

Potential and challenges of interdisciplinary research on historical window glass, stained glass and reverse glass paintings  

NASA Astrophysics Data System (ADS)

The interdisciplinary study of ancient materials has become an increasingly common strategy, mainly because it has proved to be a highly rewarding approach to studying the age, provenance and production of archaeological objects. The results of such an approach sometimes also provide answers to questions relating not only to socio-cultural, economic or technological developments in a particular region or period (trade, innovation, production etc.), but also the conservation of the materials or artefacts in question. A number of analytical methods, ranging from microscopic to elementary analyses, have been successfully applied to determine the nature of materials and technologies used in the production, as well as to identify the provenance of ancient glass. As far as window glass and stained glass is concerned, the study of architectural context and art history - as well as the technological characteristics of materials - has proved to be most helpful in determining history, production and artistic importance of the objects under study. This paper discusses some of the multidisciplinary studies that the Vitrocentre Romont has conducted on early medieval window glass, stained glass and reverse glass paintings and illustrates the potential of a holistic approach in solving questions about materials, techniques, window design and conservation. It also addresses the limitations of the approach, which are often related to finding appropriate (i.e. non-destructive and possibly portable) methods for the analysis of sometimes extremely fragile stained glass windows.

Trümpler, Stefan; Wolf, Sophie; Kessler, Cordula; Goll, Jürg

329

Waste glass leaching and alteration under conditions of open site tests  

SciTech Connect

The behavior of waste glass was investigated under open site disposal conditions. This glass was produced by vitrification of intermediate level radioactive waste from nuclear power plants. Two types of borosilicate glasses were obtained for two different reactor wastes, WWER and RBMK. Leaching and alteration mechanisms are discussed as well as the data processing technique used for these long term tests. The decay of radionuclides was accounted for in order to obtain correct results. The leaching factors obtained can be used for the assessment of radionuclide retention. Discontinuous leaching of Cs-137 has been observed during more than 8 years testing time. The fluctuating leaching rate depends on glass composition. The average leaching rate remains within (0.4--4){micro}g/sq.sm{center_dot}day. Alteration of waste glass includes the formation of surface layers and cracks on the glass surface. SEM analysis of glass was used to show these surface layers. The thickness of the layers was determined to be within 2--6 {micro}m. The structure of these layers depends on glass composition and the interfacing environment.

Sobolev, I.A.; Ojovan, M.I.; Batyukhnova, O.G.; Ojovan, N.V.; Scherbatova, T.D. [Scientific and Industrial Association Radon, Moscow (Russian Federation)

1997-12-31

330

X-ray absorption studies of bismuth valence and local environments in borosilicate waste glasses  

NASA Astrophysics Data System (ADS)

X-ray absorption spectra (XAS) were collected and analyzed to characterize bismuth (Bi) environments in borosilicate glass formulations developed for the immobilization of high level nuclear wastes (HLW), from the bismuth phosphate process. Therefore, the structural role of Bi in these glasses is of interest; in addition in the present study, more particular interest in Bi originated from unusual foaming that was observed during melt cooling, where it was initially suspected that Bi 3+ reduction to Bi 0 may generate oxygen that caused the foaming. Observations from scanning electron microscopy of some HLW glass samples indicated a Bi-phosphate association. Bi L III XAS of 13 Bi-containing waste glass formulations of various compositions were measured that exhibited varying degrees of melt foaming. The Bi XAS are similar for all glasses investigated, and indicate Bi 3+O 3 nearest-neighbor environments with Bi-O distances near 2.13 Å. This environment is similar to the most localized Bi coordination characteristics in the crystalline Bi-silicates, eulytite (Bi 4Si 3O 12) and bismutoferrite (BiFe 2Si 2O 8OH). However, the Bi-environments in the glasses are distinctly different from the Bi-site in crystalline BiPO 4; therefore, XAS indicates no evidence of Bi-phosphate domains in the glasses measured. No XAS evidence was observed in any of the glasses investigated for Bi clustering, such as metallic Bi, or Bi-O-Bi bonding. Since the local Bi environments look similar for all glasses investigated, Bi XAS data and analyses show no association of the melt foaming problems with changes of Bi environments in the corresponding glass. The foaming may be dependent on chromate or phosphate behavior in the glass structure.

McKeown, David A.; Gan, Hao; Pegg, Ian L.

2012-01-01

331

Ion implantation in silicate glasses  

SciTech Connect

This review examines the effects of ion implantation on the physical properties of silicate glasses, the compositional modifications that can be brought about, and the use of metal implants to form colloidal nanosize particles for increasing the nonlinear refractive index.

Arnold, G.W.

1993-12-01

332

Dispersion of barium gallogermanate glass.  

PubMed

Gallogermanate glasses are the subject of intense study as a result of their unique combination of physical and optical properties, including transmission from 0.4 to beyond 5.0 microm. These glasses can be easily made into large optics with high-index homogeneity for numerous U.S. Department of Defense and commercial visible-IR window applications such as reconnaissance, missile domes, IR countermeasures, avionics, and collision avoidance on automobiles. These applications require a knowledge of the refractive index of glass throughout the region of transmission. Consequently, we have measured the refractive index of BaO-Ga2O3-GeO2 glass from 0.4 to 5.0 microm and calculated the Sellmeier coefficients required for optical device design. PMID:11900015

Zelmon, David E; Bayya, Shyam S; Sanghera, Jasbinder S; Aggarwal, Ishwar D

2002-03-01

333

High Tech Art: Chameleon Glass  

NASA Technical Reports Server (NTRS)

Dichroic Glass is a technology wherein extremely thin films of metal are vacuum deposited on a glass surface. The coated glass shields spacecraft instruments from cosmic radiation and protects human vision from unfiltered sunlight in space. Because the coating process allows some wavelengths of light and color to reflect and others to pass through, a chameleon effect is produced. Murray Schwartz, a former aerospace engineer, has based his business KROMA on this NASA optical technology. He produces dichroic stained glass windows, mobiles and jewelry. The technique involves deposition of super thin layers of metal oxides applied one layer at a time in a specific order and thickness for the desired effect. His product line is unique and has been very successful.

1993-01-01

334

2012 Problem 13: Misty Glass  

NASA Astrophysics Data System (ADS)

Based on diffraction theory, we propose a model to explain the formation of colorful rings created by a misty glass. The model is verified by examining the relation between the size of the ring and size of the droplets.

Huang, Shan; Li, Xiao; Gao, Wenli; Zhou, Huijun

2015-10-01

335

Fiber glass pulling. [in space  

NASA Technical Reports Server (NTRS)

Experiments were conducted to determine the viability of performing containerless glass fiber pulling in space. The optical transmission properties and glass-forming capabilities of the heavy metal fluorides are reviewed and the acoustic characteristics required for a molten glass levitation system are examined. The design limitations of, and necessary modifications to the acoustic levitation furnace used in the experiments are discussed in detail. Acoustic levitator force measurements were performed and a thermal map of the furnace was generated from thermocouple data. It was determined that the thermal capability of the furnace was inadequate to melt a glass sample in the center. The substitution of a 10 KW carbon monoxide laser for the original furnace heating elements resulted in improved melt heating.

Workman, Gary L.

1987-01-01

336

Chalcogenide glass based integrated photonics  

NASA Astrophysics Data System (ADS)

Chalcogenide glasses, namely the amorphous compounds containing sulfur, selenium, and/or tellurium, have emerged as a promising material candidate for integrated photonics given their wide infrared transparency window, low processing temperature, almost infinite capacity for composition alloying, as well as high linear and nonlinear indices. Here we present the fabrication and characterization of chalcogenide glass based photonic devices integrated on silicon as well as on flexible polymer substrates for sensing, optical interconnect and nonlinear optics applications.

Li, Lan; Lin, Hongtao; Zou, Yi; Ogbuu, Okechukwu; Danto, Sylvain; Musgraves, J. David; Richardson, Kathleen; Hu, Juejun

2012-11-01

337

Gene activation by bioactive glasses  

Microsoft Academic Search

Bioactive glasses have been shown to regulate gene expression in both hard and soft tissue repair. New resorbable bioactive\\u000a glass constructs are now being developed that can influence gene expression in the local environment by manipulating material\\u000a properties such as the surface chemistry, topography and the release of dissolution ions. The success of these scaffolds,\\u000a however, may depend upon a

G. Jell; M. M. Stevens

2006-01-01

338

Luminescence of powdered uranium glasses  

NASA Technical Reports Server (NTRS)

Measurement of cathodoluminescence and photoluminescence efficiencies in powdered borosilicate glasses having different particle size and different uranium content. Excitation with 100 to 350 keV electrons and with 253.7 nm light was found to produce identical absolute radiant exitance spectra in powdered samples. The most efficient glass was one containing 29.4 wt% B2O3, 58.8 wt% SiO2, 9.8 wt% Na2O and 2.0 wt% UO2.

Eubanks, A. G.; Mcgarrity, J. M.; Silverman, J.

1974-01-01

339

High Verdet constant Faraday rotator glasses  

Microsoft Academic Search

Faraday rotator glasses with high Verdet constants are used for optical isolators and sensors. Based on the Tb2O3 -B2O3-Al2O3- SiO2 system and the effect of each component on glass formation, glass compositions were selected for development of new Faraday rotator glasses. Devitrification of Tb-glass was studied by microscopic morphology to establish the production process. Dispersion of Verdet constant and the

Yasi Jiang; Michael J. Myers; Daniel L. Rhonehouse

1993-01-01

340

Durability of simulated DWPF annealed glasses  

SciTech Connect

Simulated high-level waste glass samples of the DWPF projected compositions were annealed at various times and temperatures in order to develop time-temperature-transformation diagrams. These heat treated glasses were subjected to the Product Consistency Test (PCT) to evaluate glass durability. The B, Li, and Na concentrations in the leachate (the PCT results) were compared to the PCT results of the Environmental Assessment benchmark glass. Durability as a function of glass composition and crystallinity was also examined.

Andrews, M.K.; Cicero, C.A.; Marra, S.L.; Beam, D.C.

1993-03-01

341

Durability of simulated DWPF annealed glasses  

SciTech Connect

Simulated high-level waste glass samples of the DWPF projected compositions were annealed at various times and temperatures in order to develop time-temperature-transformation diagrams. These heat treated glasses were subjected to the Product Consistency Test (PCT) to evaluate glass durability. The B, Li, and Na concentrations in the leachate (the PCT results) were compared to the PCT results of the Environmental Assessment benchmark glass. Durability as a function of glass composition and crystallinity was also examined.

Andrews, M.K.; Cicero, C.A.; Marra, S.L.; Beam, D.C.

1993-01-01

342

Fabrication of glass microspheres with conducting surfaces  

DOEpatents

A method for making hollow glass microspheres with conducting surfaces by adding a conducting vapor to a region of the glass fabrication furnace. As droplets or particles of glass forming material pass through multiple zones of different temperature in a glass fabrication furnace, and are transformed into hollow glass microspheres, the microspheres pass through a region of conducting vapor, forming a conducting coating on the surface of the microspheres.

Elsholz, William E. (Acampo, CA)

1984-01-01

343

Fabrication of glass microspheres with conducting surfaces  

DOEpatents

A method for making hollow glass microspheres with conducting surfaces by adding a conducting vapor to a region of the glass fabrication furnace. As droplets or particles of glass forming material pass through multiple zones of different temperature in a glass fabrication furnace, and are transformed into hollow glass microspheres, the microspheres pass through a region of conducting vapor, forming a conducting coating on the surface of the microspheres.

Elsholz, W.E.

1982-09-30

344

Glass Membrane For Controlled Diffusion Of Gases  

DOEpatents

A glass structure for controlled permeability of gases includes a glass vessel. The glass vessel has walls and a hollow center for receiving a gas. The glass vessel contains a metal oxide dopant formed with at least one metal selected from the group consisting of transition metals and rare earth metals for controlling diffusion of the gas through the walls of the glass vessel. The vessel releases the gas through its walls upon exposure to a radiation source.

Shelby, James E. (Alfred Station, NY); Kenyon, Brian E. (Pittsburgh, PA)

2001-05-15

345

Metallic Glass Cooling  

NASA Technical Reports Server (NTRS)

A sample of advanced metallic glass alloy cools down during an experiment with the TEMPUS furnace on STS-94, July 7, 1997, MET:5/23:35 (approximate). The sequence shows the sample glowing, then fading to black as scientists began the process of preserving the liquid state, but lowering the temperature below the normal solidification temperature of the alloy. This process is known as undercooling. (10 second clip covering approximately 50 seconds.) TEMPUS (stands for Tiegelfreies Elektromagnetisches Prozessiere unter Schwerelosigkeit (containerless electromagnetic processing under weightlessness). It was developed by the German Space Agency (DARA) for flight aboard Spacelab. The DARA project scientist was Igon Egry. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). DARA and NASA are exploring the possibility of flying an advanced version of TEMPUS on the International Space Station. (354KB JPEG, 2700 x 2038 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300189.html.

2003-01-01

346

BNFL Report Glass Formers Characterization  

SciTech Connect

The objective of this task was to obtain powder property data on candidate glass former materials, sufficient to guide conceptual design and estimate the cost of glass former handling facilities as requested under Part B1 of BNFL Technical and Development Support. Twenty-nine glass forming materials were selected and obtained from vendors for the characterization of their physical properties, durability in caustic solution, and powder flow characteristics. A glass former was selected based on the characterization for each of the ten oxide classes required for Envelope A, B, and C mixtures. Three blends (A, B, and C) were prepared based on formulations provided by Vitreous State Laboratory and evaluated with the same methods employed for the glass formers. The properties obtained are presented in a series of attached Tables. It was determined that five of the ten glass formers, (kyanite, iron oxide, titania, zircon, and zinc oxide) have the potential to cause some level of solids f low problems. The problems might include arching or ratholing in the silo/hopper. In addition, all of the blends may require consideration for their handling.

Schumacher, R.F.

2000-07-27

347

BNFL Report Glass Formers Characterization  

SciTech Connect

The objective of this task was to obtain powder property data on candidate glass former materials, sufficient to guide conceptual design and estimate the cost of glass former handling facilities as requested under Part B1 of BNFL Technical and Development Support. Twenty-nine glass forming materials were selected and obtained from vendors for the characterization of their physical properties, durability in caustic solution, and powder flow characteristics. A glass former was selected based on the characterization for each of the ten oxide classes required for Envelope A, B, and C mixtures. Three blends (A, B, and C) were prepared based on formulations provided by Vitreous State Laboratory and evaluated with the same methods employed for the glass formers. The properties obtained are presented in a series of attached Tables. It was determined that five of the ten glass formers, (kyanite, iron oxide, titania, zircon, and zinc oxide) have the potential to cause some level of solids f low problems. In addition, all of the blends may require consideration for their handling. A number of engineering considerations and recommendations were prepared based on the experimental findings, experience, and other process considerations. Recommendations for future testing are included. In conjunction with future work, it is recommended that a professional consultant be engaged to guide and assist with testing and design input.

Schumacher, R.F.

2000-07-27

348

Space processing of chalcogenide glass  

NASA Technical Reports Server (NTRS)

The manner in which the weightless, containerless nature of in-space processing can be successfully utilized to improve the quality of infrared transmitting chalcogenide glasses was investigated. The following conclusions were reached: (1) Laboratory experiments have established the techniques, processes and equipment necessary for the production of high purity chalcogenide glasses. (2) Processing techniques have been successfully adopted for Ge28Sb12Se60 glass in a 1-g environment. (3) The Ge28Sb12Se60 glasses that have been processed have optical transmission around 63% (5 mm thick). (4) Laboratory experiments have established that the use of precursor materials in powdered form increases the oxygen contamination of the processed glass. This indicates that high purity precursor materials in bar or pellet form should be used. (5) Modifications were made on the MSFC acoustic levitator in an attempt to improve levitation stability during long-time experiments. Room temperature experiments on As2S3 glasses and high temperature experiments on polystyrene were conducted.

Ali, M. A.; Larsen, D. C.

1976-01-01

349

Long-term modeling of alteration-transport coupling: Application to a fractured Roman glass  

NASA Astrophysics Data System (ADS)

To improve confidence in glass alteration models, as used in nuclear and natural applications, their long-term predictive capacity has to be validated. For this purpose, we develop a new model that couples geochemical reactions with transport and use a fractured archaeological glass block that has been altered for 1800 years under well-constrained conditions in order to test the capacity of the model. The chemical model considers three steps in the alteration process: (1) formation of a hydrated glass by interdiffusion, whose kinetics are controlled by a pH and temperature dependent diffusion coefficient; (2) the dissolution of the hydrated glass, whose kinetics are based on an affinity law; (3) the precipitation of secondary phases if thermodynamic saturation is reached. All kinetic parameters were determined from experiments. The model was initially tested on alteration experiments in different solutions (pure water, Tris, seawater). It was then coupled with diffusive transport in solution to simulate alteration in cracks within the glass. Results of the simulations run over 1800 years are in good agreement with archaeological glass block observations concerning the nature of alteration products (hydrated glass, smectites, and carbonates) and crack alteration thicknesses. External cracks in direct contact with renewed seawater were altered at the forward dissolution rate and are filled with smectites (400-500 ?m). Internal cracks are less altered (by 1 or 2 orders of magnitude) because of the strong coupling between alteration chemistry and transport. The initial crack aperture, the distance to the surface, and sealing by secondary phases account for these low alteration thicknesses. The agreement between simulations and observations thus validates the predictive capacity of this coupled geochemical model and increases more generally the robustness and confidence in glass alteration models to predict long-term behavior of nuclear waste in geological disposal or natural glass in the environment.

Verney-Carron, Aurélie; Gin, Stéphane; Frugier, Pierre; Libourel, Guy

2010-04-01

350

Spheroidization of glass powders for glass ionomer cements.  

PubMed

Commercial angular glass powders were spheroidized using both the flame spraying and inductively coupled radio frequency plasma spraying techniques. Spherical powders with different particle size distributions were obtained after spheroidization. The effects of spherical glass powders on the mechanical properties of glass ionomer cements (GICs) were investigated. Results showed that the particle size distribution of the glass powders had a significant influence on the mechanical properties of GICs. Powders with a bimodal particle size distribution ensured a high packing density of glass ionomer cements, giving relatively high mechanical properties of GICs. GICs prepared by flame-spheroidized powders showed low strength values due to the loss of fine particles during flame spraying, leading to a low packing density and few metal ions reacting with polyacrylic acid to form cross-linking. GICs prepared by the nano-sized powders showed low strength because of the low bulk density of the nano-sized powders and hence low powder/liquid ratio of GICs. PMID:15046893

Gu, Y W; Yap, A U J; Cheang, P; Kumar, R

2004-08-01

351

A Cosmic Magnifying Glass  

NASA Technical Reports Server (NTRS)

Scanning the heavens for the first time since the successful December 1999 servicing mission, NASA's Hubble Space Telescope imaged a giant, cosmic magnifying glass, a massive cluster of galaxies called Abell 2218. This 'hefty' cluster resides in the constellation Draco, some 2 billion light-years from Earth. The cluster is so massive that its enormous gravitational field deflects light rays passing through it, much as an optical lens bends light to form an image. This phenomenon, called gravitational lensing, magnifies, brightens, and distorts images from faraway objects. The cluster's magnifying powers provides a powerful 'zoom lens' for viewing distant galaxies that could not normally be observed with the largest telescopes. The picture is dominated by spiral and elliptical galaxies. Resembling a string of tree lights, the biggest and brightest galaxies are members of the foreground cluster. Researchers are intrigued by a tiny red dot just left of top center. This dot may be an extremely remote object made visible by the cluster's magnifying powers. Further investigation is needed to confirm the object's identity. The color picture already reveals several arc-shaped features that are embedded in the cluster and cannot be easily seen in the black-and- white image. The colors in this picture yield clues to the ages, distances, and temperatures of stars, the stuff of galaxies. Blue pinpoints hot young stars. The yellow-white color of several of the galaxies represents the combined light of many stars. Red identifies cool stars, old stars, and the glow of stars in distant galaxies. This view is only possible by combining Hubble's unique image quality with the rare lensing effect provided by the magnifying cluster.

2000-01-01

352

Glass: Kohlrausch exponent, fragility, anharmonicity.  

PubMed

The thermodynamical and mechanical properties of (fragile and strong) glass are modeled based on a generalised activation energy relationship log( ? ) = ?G ( ? )/RTn(T') process of glass-forming liquids. This cooperative process involves 1/n(T') elementary ? motions of activation Gibbs energy ?G ( ? ) dependent on the equivalent temperature T', the temperature of the liquid in equilibrium having the volume of the glass, function of temperature and aging conditions. From this modified VFT law the relaxation of any properties (V , H , stress, creep) can be calculated and approximated by the Kohlrausch function. This model predicts consistency relationships for: a) the temperature (and aging time) variation of the Kohlrausch exponent; b) the temperature dependence of the stabilisation time domain of strong and fragile glass; c) the linear relation between the activation parameters (E (*) energy, S (*) entropy, V (*) volume) of the ? and ? transition. The Lawson and Keyes (LK) relations are recalled and it is shown that these relations (somewhat equivalant to the compensation law or Meyer-Neldel rule) are observed generally in glass. Morever the (macroscopic) ratios ?H/?V observed during aging or after a temperature jump and the (microscopic) ratio E (*)/V (*) are found equal to ?? (? compressibily, ? Grüneisen parameter), in agreement with the LK predictions. From various experiments and in agreement with predictions of this model we conclude that the Grüneisen parameter ? ( B ) (pressure derivative of the bulk modulus) and the Mean Square Displacement (MSD) characterising the anharmonicity of solids (and liquids) are the main parameters which govern the relaxation properties of the glass state. Linear relations between the parameters ? ( B ), the fragility m, and the Kohlrausch exponent n ( g ) at T ( g ) are explained. These correlations underscore a strong relationship between the fragilty of glass formers and the extent of the anharmonicity in the interatomic interactions. PMID:22526977

Rault, J

2012-04-01

353

The formation of crystals in glasses containing rare earth oxides  

SciTech Connect

Korean spent nuclear fuel will reach the capacity of the available temporary storage by 2016. Pyroprocessing and direct disposal seems to be an alternative way to manage and reuse spent nuclear fuel while avoiding the wet reprocessing technology. Pyroprocessing produces several wastes streams, including metals, salts, and rare earths, which must be converted into stabilized form. A suitable form for rare earth immobilization is borosilicate glass. The borosilicate glass form exhibits excellent durability, allows a high waste loading, and is easy to process. In this work, we combined the rare earths waste of composition (in wt%) 39.2Nd{sub 2}O{sub 3}–22.7CeO{sub 2}–11.7La{sub 2}O{sub 3}–10.9PrO{sub 2}–1.3Eu{sub 2}O{sub 3}–1.3Gd{sub 2}O{sub 3}–8.1Sm{sub 2}O{sub 3}–4.8Y{sub 2}O{sub 3} with a baseline glass of composition 60.2SiO{sub 2}–16.0B{sub 2}O{sub 3}–12.6Na{sub 2}O–3.8Al{sub 2}O{sub 3}–5.7CaO–1.7ZrO{sub 2}. Crystallization in waste glasses occurs as the waste loading increases. It may produce complicate glass processing and affect the product quality. To study crystal formation, we initially made glasses containing 5%, 10% and 15% of La{sub 2}O{sub 3} and then glasses with 5%, 10% and 15% of the complete rare earth mix. Samples were heat-treated for 24 hours at temperatures 800°C to 1150°C in 50°C increments. Quenched samples were analyzed using an optical microscope, scanning electron microscope with energy dispersive spectroscopy, and x-ray diffraction. Stillwellite (LaBSiO{sub 5}) and oxyapatite (Ca{sub 2}La{sub 8}Si{sub 6}O{sub 26}) were found in glasses containing La{sub 2}O{sub 3}, while oxyapatite (Ca{sub 2}La{sub 8}Si{sub 6}O{sub 26} and NaNd{sub 9}Si{sub 6}O{sub 26}) precipitated in glasses with additions of mixed rare earths. The liquidus temperature (T{sub L}) of the glasses containing 5%, 10% and 15% La{sub 2}O{sub 3} were 800°C, 959°C and 986°C, respectively; while T{sub L} was 825°C, 1059°C and 1267°C for glasses with 5%, 10% and 15% addition of mixed rare earth oxides. The component coefficients T{sub B2O3}, T{sub SiO2}, T{sub CaO}, and T{sub RE2O3} were also evaluated using a recently published study.

Fadzil, Syazwani Mohd [Pohang University of Science and Technology (POSTECH), Pohang (Korea, Republic of); Hrma, Pavel [Pohang University of Science and Technology (POSTECH), Pohang, South Korea and Pacific Northwest National Laboratory, Richland, Washington (United States); Crum, Jarrod [Pacific Northwest National Laboratory, Richland, Washington (United States); Siong, Khoo Kok; Ngatiman, Mohammad Fadzlee; Said, Riduan Mt [National University of Malaysia, Bandar Baru Bangi, Selangor (Malaysia)

2014-02-12

354

Iron phosphate glass for immobilization of 99Tc  

SciTech Connect

Technetium-99 (99Tc) can bring serious environmental threats because of its long half-life (t1/2 = ~2.1 x 105 years), high fission yield (~6%), and high solubility and mobility in the ground water. The high volatility makes it difficult to immobilize 99Tc in continuous melters vitrifying 99Tc-containing nuclear wastes in borosilicate glasses. This work explores a possibility of incorporating a high concentration of 99Tc, surrogated by the non-radioactive Re, in an iron phosphate glass by melting mixtures of iron phosphate glass frits with 1.5-6 mass% KReO4 at ~1000 C. The retention of Re achieved was ~1.1 mass%. The normalized Re release by the 7-day Product Consistency Test was <10*2 g/m2. Surprisingly, the Re escaped from the melt within a short time of heating, especially when the temperature was increased. Therefore, 99Tc volatilization would still be a challenging task for its immobilization in iron phosphate glasses.

Xu, Kai; Hrma, Pavel R.; Um, Wooyong; Heo, Jong

2013-06-15

355

Structure and thermal properties of yttrium alumino-phosphate glasses  

NASA Astrophysics Data System (ADS)

The structure and thermal properties of yttrium alumino-phosphate glasses, of nominal composition (Y2O3)0.31-z(Al2O3)z(P2O5)0.69 with 0 \\lesssim z \\lesssim 0.31 , were studied by using a combination of neutron diffraction, 27Al and 31P magic angle spinning nuclear magnetic resonance, differential scanning calorimetry and thermal gravimetric analysis methods. The Vickers hardness of the glasses was also measured. The data are compared to those obtained for pseudo-binary Al2O3-P2O5 glasses and the structure of all these materials is rationalized in terms of a generic model for vitreous phosphate materials in which Y3+ and Al3+ act as modifying cations that bind only to the terminal (non-bridging) oxygen atoms of PO4 tetrahedra. The results are used to help elucidate the phenomenon of rare-earth clustering in phosphate glasses which can be reduced by substituting Al3+ ions for rare-earth R3+ ions at fixed modifier content.

Martin, Richard A.; Salmon, Philip S.; Carroll, Donna L.; Smith, Mark E.; Hannon, Alex C.

2008-03-01

356

Power laser application for security glass production  

NASA Astrophysics Data System (ADS)

Modern glass application needs to move from traditional tempering with only average controlled fragmentation of security glass to computerized controlled fragmentation by developing engineered stress profiles in glass article. The new treatment methods of soda-lime float glass using irradiation by power Nd:YAG laser which is moved by robot will be discussed. The transparency of glass for laser wavelength is one of the problems of glass treatment by laser. Noncontact stress control by light scattering will be shown. The two main objectives of this work will be discussed: 1. Glass treatment by power laser beam directed to secure glass production; 2. Control methods of residual stress into float glasses treated by laser.

Abashkin, Vladimir; Achimova, Elena

2009-09-01

357

Power laser application for security glass production  

NASA Astrophysics Data System (ADS)

Modern glass application needs to move from traditional tempering with only average controlled fragmentation of security glass to computerized controlled fragmentation by developing engineered stress profiles in glass article. The new treatment methods of soda-lime float glass using irradiation by power Nd:YAG laser which is moved by robot will be discussed. The transparency of glass for laser wavelength is one of the problems of glass treatment by laser. Noncontact stress control by light scattering will be shown. The two main objectives of this work will be discussed: 1. Glass treatment by power laser beam directed to secure glass production; 2. Control methods of residual stress into float glasses treated by laser.

Abashkin, Vladimir; Achimova, Elena

2010-05-01

358

Investigation of Glass Transition Temperature of Binary Tellurite Glasses  

SciTech Connect

Five series of binary Tellurite glass samples containing Sb{sub 2}O{sub 4}, WO{sub 3}, Fe{sub 2}O{sub 3}, Na{sub 2}O and ZnO{sub 2} are studied in terms of the variation of glass transition temperature (T{sub g}). It is seen that Tg increases as Tellurite concentration decreases in the case of glasses containing metal oxides Sb{sub 2}O{sub 4} WO{sub 3}, and Fe{sub 2}O{sub 3} while T{sub g} shows a decreasing trend with that of Na{sub 2}O and ZnO and the corresponding changes in the network structure are accounted to possible extent. The structural variations are analyzed using the concept of electronegativity.

Chippy, L.; Unnithan, C. Harikuttan [Solid State Physics Laboratory, D.B. College, Sasthamcotta, Kollam, Kerala-690 521 (India); Jayakumar, S. [MSM College, Kayamkulam, Kerala (India)

2011-10-20

359

Multiple reentrant glass transitions in confined hard-sphere glasses  

E-print Network

Glass forming liquids exhibit a rich phenomenology upon confinement. This is often related to the effects arising from wall-fluid interactions. Here we focus on the interesting limit where the separation of the confining walls becomes of the order of a few particle diameters. For a moderately polydisperse, densely packed hard-sphere fluid confined between two smooth hard walls, we show via event-driven molecular dynamics simulations the emergence of a multiple reentrant glass transition scenario upon a variation of the wall separation. Using thermodynamic relations, this reentrant phenomenon is shown to persist also under constant chemical potential. This allows straightforward experimental investigation and opens the way to a variety of applications in micro- and nanotechnology, where channel dimensions are comparable to the size of the contained particles. The results are in-line with theoretical predictions obtained by a combination of density functional theory and the mode-coupling theory of the glass transition.

S. Mandal; S. Lang; M. Gross; M. Oettel; D. Raabe; T. Franosch; F. Varnik

2014-06-20

360

GLASS FABRICATION AND PRODUCT CONSISTENCY TESTING OF LANTHANIDE BOROSILICATE FRIT B COMPOSITION FOR PLUTONIUM DISPOSITION  

SciTech Connect

The Department of Energy Office of Environmental Management (DOE/EM) plans to conduct the Plutonium Disposition Project at the Savannah River Site (SRS) to disposition excess weapons-usable plutonium. A plutonium glass waste form is a leading candidate for immobilization of the plutonium for subsequent disposition in a geologic repository. A reference glass composition (Lanthanide Borosilicate (LaBS) Frit B) was developed during the Plutonium Immobilization Program (PIP) to immobilize plutonium. A limited amount of performance testing was performed on this baseline composition before efforts to further pursue Pu disposition via a glass waste form ceased. Therefore, the objectives of this present task were to fabricate plutonium loaded LaBS Frit B glass and perform additional testing to provide near-term data that will increase confidence that LaBS glass product is suitable for disposal in the Yucca Mountain Repository. Specifically, testing was conducted in an effort to provide data to Yucca Mountain Project (YMP) personnel for use in performance assessment calculations. Plutonium containing LaBS glass with the Frit B composition with a 9.5 wt% PuO{sub 2} loading was prepared for testing. Glass was prepared to support Product Consistency Testing (PCT) at Savannah River National Laboratory (SRNL) and for additional performance testing at Argonne National Laboratory (ANL) and Pacific Northwest National Laboratory (PNNL). The glass was characterized using x-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) prior to performance testing. A series of PCTs were conducted at SRNL with varying exposed surface area and test durations. The leachates from these tests were analyzed to determine the dissolved concentrations of key elements. Acid stripping of leach vessels was performed to determine the concentration of the glass constituents that may have sorbed on the vessels during leach testing. Additionally, the leachate solutions were ultrafiltered to quantify colloid formation. The leached solids from select PCTs were examined in an attempt to evaluate the Pu and neutron absorber release behavior from the glass and to identify the formation of alteration phases on the glass surface. Characterization of the glass prior to testing revealed that some undissolved plutonium oxide was present in the glass. The undissolved particles had a disk-like morphology and likely formed via coarsening of particles in areas compositionally enriched in plutonium. Similar disk-like PuO{sub 2} phases were observed in previous LaBS glass testing at PNNL. In that work, researchers concluded that plutonium formed with this morphology as a result of the leaching process. It was more likely that the presence of the plutonium oxide crystals in the PNNL testing was a result of glass fabrication. A series of PCTs were conducted at 90 C in ASTM Type 1 water. The PCT-Method A (PCT-A) was conducted to compare the Pu LaBS Frit B glass durability to current requirements for High Level Waste (HLW) glass in a geologic repository. The PCT-A test has a strict protocol and is designed to specifically be used to evaluate whether the chemical durability and elemental release characteristics of a nuclear waste glass have been consistently controlled during production and, thus, meet the repository acceptance requirements. The PCT-A results on the Pu containing LaBS Frit B glass showed that the glass was very durable with a normalized elemental release value for boron of approximately 0.02 g/L. This boron release value was better than two orders of magnitude better from a boron release standpoint than the current Environmental Assessment (EA) glass used for repository acceptance. The boron release value for EA glass is 16.7 g/L.

Marra, J

2006-01-19

361

Mechanisms of Rhyolitic Glass Hydration Below the Glass Transition  

SciTech Connect

Although a great deal is known about the interaction between water and rhyolitic glasses and melts at temperatures above the glass transition, the nature of this interaction at lower temperatures is much more obscure. Comparisons between high- and low-temperature diffusion studies suggest that several factors play important roles under lower-temperature conditions that are not significant at higher temperatures. Water concentrations in rhyolitic glasses hydrated at low temperatures are significantly greater than in those hydrated at high temperatures and low pressures. Surface concentrations, which equilibrate quickly with the surrounding environment at high temperature, change far more slowly as temperature decreases, and may not equilibrate at room temperature for hundreds or thousands of years. Temperature extrapolations of high- and low-temperature diffusion data are not consistent, suggesting that a change in mechanism occurs. These differences may be due to the inability of "self-stress," caused by the in-diffusing species, to relax at lower temperature. Preliminary calculations suggest that the level of stress caused by glass-water interaction may be greater than the tensile strength of the glass. On a microstuctural scale, extrapolations of high-temperature Fourier transform infrared spectroscopy (FTIR) data to lower temperatures suggests that there should be little or no hydroxyl present in glasses hydrated at low temperature. Comparisons of low-temperature hydration results among SiO2, obsidian, and albite compositions show distinct differences, and features are present in the spectra that do not occur at high temperature. Analysis of H2O and D2O diffusion also suggest that mechanistic differences occur between low- and high-temperature diffusive processes.

Anovitz, Lawrence {Larry} M [ORNL; Cole, David R [ORNL; Fayek, Mostafa [University of Manitoba, Canada

2008-01-01

362

Fabrication and characterization of MCC approved testing material - ATM-8 glass  

SciTech Connect

The Materials Characterization Center (MCC) Approved Testing Material ATM-8 is a borosilicate glass that incorporates elements typical of high-level waste (HLW) resulting from the reprocessing of commercial nuclear reactor fuel. Its composition is based upon the simulated HLW glass type 76-68 (Mendel, J.E. et al., 1977, Annual Report of the Characteristics of High-Level Waste Glasses, BNWL-2252, Pacific Northwest Laboratory, Richland, Washington), to which depleted uranium, technetium-99, neptunium-237 and plutonium-239 have been added at moderate to low levels. The glass was requested by the Nevada Nuclear Waste Storage Investigations (NNWSI) Project. It was produced by the MCC at the Pacific Northwest Laboratory (PNL) operated for the Department of Energy (DOE) by Battelle Memorial Institute. ATM-8 glass was produced in April of 1984, and is the second in a series of testing materials for NNWSI. This report discusses its fabrication (starting materials, batch and glass preparation, measurement and testing equipment, other equipment, procedures, identification system and materials availability and storage, and characterization (bulk density) measurements, chemical analysis, microscopic examination, and x-ray diffraction analysis. 4 refs., 2 figs., 10 tabs.

Wald, J.W.

1985-10-01

363

Monte Carlo Simulations of the Corrosion of Aluminoborosilicate Glasses  

SciTech Connect

Aluminum is one of the most common components included in nuclear waste glasses. Therefore, Monte Carlo (MC) simulations were carried out to investigate the influence of aluminum on the rate and mechanism of dissolution of sodium borosilicate glasses in static conditions. The glasses studied were in the compositional range (70-2x)% SiO2 x% Al2O3 15% B2O3 (15+x)% Na2O, where 0 ? x ? 15%. The simulation results show that increasing amounts of aluminum in the pristine glasses slow down the initial rate of dissolution as determined from the rate of boron release. However, the extent of corrosion - as measured by the total amount of boron release - initially increases with addition of Al2O3, up to 5 Al2O3 mol%, but subsequently decreases with further Al2O3 addition. The MC simulations reveal that this behavior is due to the interplay between two opposing mechanisms: (1) aluminum slows down the kinetics of hydrolysis/condensation reactions that drive the reorganization of the glass surface and eventual formation of a blocking layer; and (2) aluminum strengthens the glass thereby increasing the lifetime of the upper part of its surface and allowing for more rapid formation of a blocking layer. Additional MC simulations were performed whereby a process representing the formation of a secondary aluminosilicate phase was included. Secondary phase formation draws dissolved glass components out of the aqueous solution, thereby diminishing the rate of condensation and delaying the formation of a blocking layer. As a result, the extent of corrosion is found to increase continuously with increasing Al2O3 content, as observed experimentally. For Al2O3 < 10 mol%, the MC simulations also indicate that, because the secondary phase solubility eventually controls the aluminum content in the part of the altered layer in contact with the bulk aqueous solution, the dissolved aluminum and silicon concentrations at steady state are not dependent on the Al2O3 content of the pristine aluminoborosilicate glass.

Kerisit, Sebastien N.; Ryan, Joseph V.; Pierce, Eric M.

2013-10-15

364

Monte Carlo Simulations of the Corrosion of Aluminoborosilicate Glasses  

SciTech Connect

Aluminum is one of the most common components included in nuclear waste glasses. Therefore, Monte Carlo (MC) simulations were carried out to investigate the influence of aluminum on the rate and mechanism of dissolution of sodium borosilicate glasses in static conditions. The glasses studied were in the compositional range (70 2x)% SiO2x% Al2O3 15% B2O3 (15 + x)% Na2O, where 0 x 15%. The simulation results show that increasing amounts of aluminum in the pristine glasses slow down the initial rate of dissolution as determined from the rate of boron release. However, the extent of corrosion as measured by the total amount of boron release initially increases with addition of Al2O3, up to 5 mol% Al2O3, but subsequently decreases with further Al2O3 addition. The MC simulations reveal that this behavior is due to the interplay between two opposing mechanisms: (1) aluminum slows down the kinetics of hydrolysis/condensation reactions that drive the reorganization of the glass surface and eventual formation of a blocking layer; and (2) aluminum strengthens the glass thereby increasing the lifetime of the upper part of its surface and allowing for more rapid formation of a blocking layer. Additional MC simulations were performed whereby a process representing the formation of a secondary aluminosilicate phase was included. Secondary phase formation draws dissolved glass components out of the aqueous solution, thereby diminishing the rate of condensation and delaying the formation of a blocking layer. As a result, the extent of corrosion is found to increase continuously with increasing Al2O3 content, as observed experimentally. For Al2O3 < 10 mol%, the MC simulations also indicate that, because the secondary phase solubility eventually controls the aluminum content in the part of the altered layer in contact with the bulk aqueous solution, the dissolved aluminum and silicon concentrations at steady state are not dependent on the Al2O3 content of the pristine aluminoborosilicate glass.

Kerisit, Sebastien [Pacific Northwest National Laboratory (PNNL); Ryan, Joseph V [Pacific Northwest National Laboratory (PNNL); Pierce, Eric M [ORNL

2013-01-01

365

Cation field strength effects on high pressure aluminosilicate glass structure: Multinuclear NMR and La XAFS results  

NASA Astrophysics Data System (ADS)

We examined aluminosilicate glasses containing a variety of network modifying to intermediate cations (Li, La, Sc, and Fe), quenched from melts at 1 atm to 8 GPa, to further investigate the role of cation field strength in Al coordination changes and densification. 27Al Nuclear Magnetic Resonance Spectroscopy (NMR) reveals that the mean Al coordination increases with increasing pressure in the Li-containing glasses, which can be explained by a linear dependence of fractional change in Al coordination number on cation field strengths in similar K-, Na-, and Ca-containing aluminosilicate glasses (K < Na < Li < Ca). Measured recovered densities follow a similar linear trend. In contrast, the La-containing glasses have significantly lower mean Al coordination numbers at given pressures than the cation field strength of La and glass density would predict. La L 3 X-ray absorption fine structure (XAFS) spectroscopy results indicate a significant increase with pressure in average La-O bond distances, suggesting that La and Al may be "competing" for higher coordinated sites and hence that both play a significant role in the densification of these glasses, especially in the lower pressure range. However, in Na aluminosilicate glasses with small amounts of Sc, 45Sc NMR reveals only modest Sc coordination changes, which do not seem to significantly affect the mean Al coordination values. For a Li aluminosilicate glass, 17O MAS and multiple quantum magic angle spinning (3QMAS) NMR data are consistent with generation of more highly coordinated Al at the expense of non-bridging oxygen (NBO), whereas La aluminosilicate glasses have roughly constant O environments, even up to 8 GPa. Finally, we demonstrate that useful 23Na and 27Al MAS NMR spectra can be collected for Ca-Na aluminosilicate glasses containing up to 5 wt.% Fe oxide. We discuss the types of structural changes that may accompany density increases with pressure and how these structural changes are affected by the presence of different cations.

Kelsey, Kimberly E.; Stebbins, Jonathan F.; Singer, David M.; Brown, Gordon E., Jr.; Mosenfelder, Jed L.; Asimow, Paul D.

2009-07-01

366

Preparation and characterization of special glasses for sealing and other applications  

NASA Astrophysics Data System (ADS)

Glasses find wide applications, among others, in process technologies, vacuum science and technology etc. because of their desired thermo-mechanical properties and chemical durability. In particular, hermetic glass-to-metal (GM) seals are required mainly as electrical feed through for various types of gas based and electron devices, chemical process industries, including for packaging of power devices. The physico-chemical properties of glasses play important role in forming hermetic sealing with metals/alloys. The properties like thermal expansion coefficient, glass transition temperature, micro hardness, chemical durability etc. can be tailored by varying the glass composition by adding multi alkali and alkaline earth metal oxides to the base glass and varying the process parameters. We have prepared different types of glasses for the fabrication of different types of hermetic seals. Some of these are i) Lead silicate (LS) glass having SiO2, Na2O, K2O, BaO and PbO for compression type GM seals with SS304/Inconel and AISI 446 alloy ii) Borosilicate (BS) glass containing SiO2.Na2O.K20. Al2O3.B2O3 for matched type GM seals with Mo/ Kovar alloy and for uptake of synthetic dyes like Rhodamine 6G, Methylene Blue, Uranyl ions in process industries and nuclear industry iii) Sodium alumino phosphate (NAP) glass with P2O5-Na2O-B2O3-BaO- PbO for matched type GM seals with low melting metals (Al,Cu)/alloys like Cu-Be.

Shrikhande, V. K.

2009-07-01

367

HLW Glass Studies: Development of Crystal-Tolerant HLW Glasses  

SciTech Connect

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.

Matyas, Josef; Huckleberry, Adam R.; Rodriguez, Carmen P.; Lang, Jesse B.; Owen, Antionette T.; Kruger, Albert A.

2012-04-02

368

Glass matrix composites. I - Graphite fiber reinforced glass  

NASA Technical Reports Server (NTRS)

An experimental program is described in which graphite fibers of Hercules HMS and HTS, Thornel 300, and Celanese DG-12 were used to reinforce, both uniaxially and biaxially, borosilicate pyrex glass. Composite flexural strength distribution, strength as a function of test temperature, fracture toughness and oxidative stability were determined and shown to be primarily a function of fiber type and the quality of fiber-matrix bond formed during composite fabrication. It is demonstrated that the graphite fiber reinforced glass system offers unique possibilities as a high performance structural material.

Prewo, K. M.; Bacon, J. F.

1978-01-01

369

Effects of radionuclide decay on waste glass behavior: A critical review  

SciTech Connect

This paper is an extension of a chapter in an earlier report [1] that provides an updated review on the status of radiation damage problems in nuclear waste glasses. This report will focus on radiation effects on vitrified borosilicate nuclear waste glasses under conditions expected in the proposed Yucca mountain repository. Radiation effects on high-level waste glasses and their surrounding repository environment are important considerations for radionuclide immobilization because of the potential to alter the glass stability and thereby influence the radionuclide retentive properties of this waste form. The influence of radionuclide decay on vitrified nuclear waste may be manifested by several changes, including volume, stored energy, structure, microstructure, mechanical properties, and phase separation. Radiation may also affect the composition of aqueous fluids and atmospheric gases in relatively close proximity to the waste form. What is important to the radionuclide retentive properties of the repository is how these radiation effects collectively or individually influence the durability and radionuclide release from the glass in the event of liquid water contact.

Wronkiewicz, D.J.

1993-12-01

370

The valence bond glass phase  

NASA Astrophysics Data System (ADS)

We show that a new glassy phase can emerge in the presence of strong magnetic frustration and quantum fluctuations. It is a valence bond glass (VBG). We study its properties solving the Hubbard-Heisenberg model on a Bethe lattice within the large-N limit introduced by Affleck and Marston. We work out the phase diagram that contains Fermi liquid, dimer and valence bond glass phases. This new glassy phase has no electronic or spin gap (although a pseudo-gap is observed), it is characterized by long-range critical valence bond correlations and is not related to any magnetic ordering. As a consequence, it is quite different from both valence bond crystals and spin glasses.

Tarzia, M.; Biroli, G.

2008-06-01

371

Space processing of chalcogenide glasses  

NASA Technical Reports Server (NTRS)

Chalcogenide glasses are discussed as good infrared transmitters, possessing the strength, corrosion resistance, and scale-up potential necessary for large 10.6-micron windows. The disadvantage of earth-produced chalcogenide glasses is shown to be an infrared absorption coefficient which is unacceptably high relative to alkali halides. This coefficient is traced to optical nonhomogeneities resulting from environmental and container contamination. Space processing is considered as a means of improving the infrared transmission quality of chalcogenides and of eliminating the following problems: optical inhomogeneities caused by thermal currents and density fluctuation in the l-g earth environment; contamination from the earth-melting crucible by oxygen and other elements deleterious to infrared transmission; and, heterogeneous nucleation at the earth-melting crucible-glass interface.

Larsen, D. C.; Ali, M. A.

1975-01-01

372

Librational fluctuations in protein glasses.  

PubMed

Librational motions in the region of the protein "glass" (or dynamic) transition are analysed for spin-labelled haemoglobin, serum albumin and ?-lactoglobulin by EPR spectroscopy. A discontinuity in the temperature dependence of the mean-square librational amplitude, , occurs in the region of 200K as found for the mean-square atomic displacement, , at the protein dynamic transition by Mössbauer spectroscopy and neutron scattering. The discontinuity in vs. T can be described by the Vogel-Tammann-Fulcher equation, implying a finite glass transition temperature. Above the dynamic transition, vs. 1/T can be approximated by the Arrhenius law with activation energies similar to those usually found for , and relaxation processes in glass-forming media and the hydration shells of proteins. Similar results are found for librational fluctuations of membranous Na,K-ATPase spin-labelled either on superficial SH groups or on those essential to activity. PMID:23669570

Marsh, Derek; Bartucci, Rosa; Guzzi, Rita; Sportelli, Luigi; Esmann, Mikael

2013-08-01

373

Disaster medicine through Google Glass.  

PubMed

Nontechnical skills can make a difference in the management of disasters and mass casualty incidents and any tool helping providers in action might improve their ability to respond to such events. Google Glass, released by Google as a new personal communication device, could play a role in this field. We recently tested Google Glass during a full-scale exercise to perform visually guided augmented-reality Simple Triage and Rapid Treatment triage using a custom-made application and to identify casualties and collect georeferenced notes, photos, and videos to be incorporated into the debriefing. Despite some limitations (battery life and privacy concerns), Glass is a promising technology both for telemedicine applications and augmented-reality disaster response support to increase operators' performance, helping them to make better choices on the field; to optimize timings; and finally represents an excellent option to take professional education to a higher level. PMID:25460812

Carenzo, Luca; Barra, Federico Lorenzo; Ingrassia, Pier Luigi; Colombo, Davide; Costa, Alessandro; Della Corte, Francesco

2014-11-27

374

Elastic heterogeneity in metallic glasses.  

SciTech Connect

When a stress is applied on a metallic glass it deforms following Hook's law. Therefore it may appear obvious that a metallic glass deforms elastically. Using x-ray diffraction and anisotropic pair-density function analysis we show that only about 3/4 in volume fraction of metallic glasses deforms elastically, whereas the rest of the volume is anelastic and in the experimental time scale deform without resistance. We suggest that this anelastic portion represents residual liquidity in the glassy state. Many theories, such as the free-volume theory, assume the density of defects in the glassy state to be of the order of 1%, but this result shows that it is as much as a quarter.

Dmowski, , W.; Iwashita, T.; Chuang, C.-P.; Almer, J. D; Egami, T.; X-Ray Science Division; Univ. of Tennessee; ORNL

2010-01-01

375

Elastic Heterogeneity in Metallic Glasses  

SciTech Connect

When a stress is applied on a metallic glass it deforms following Hook's law. Therefore it may appear obvious that a metallic glass deforms elastically. Using x-ray diffraction and anisotropic pair-density function analysis we show that only about 3/4 in volume fraction of metallic glasses deforms elastically, whereas the rest of the volume is anelastic and in the experimental time scale deform without resistance. We suggest that this anelastic portion represents residual liquidity in the glassy state. Many theories, such as the free-volume theory, assume the density of defects in the glassy state to be of the order of 1%, but this result shows that it is as much as a quarter.

Dmowski, Wojciech [ORNL; Iwashita, T. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Chuang, C.-P. [University of Tennessee, Knoxville (UTK); Almer, J. [Argonne National Laboratory (ANL); Egami, T. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL)

2010-01-01

376

DEVELOPMENT OF CRYSTAL-TOLERANT WASTE GLASSES  

SciTech Connect

The loading of high-level waste in borosilicate glasses is limited by crystallinity constraints that cannot prevent crystal accumulation on the melter bottom and in the glass discharge riser of the melter. Pacific Northwest National Laboratory is studying variations in composition that are designed to constrain high-level waste glass compositions and develop the crystal-tolerant high-level waste glasses. These glasses will allow high waste loading without decreasing the lifetime of the melter by keeping the small spinel crystals suspended in the molten glass. Adding ~1 wt% of NiO to the baseline glass caused large spinel crystals to form up to 210 µm in size and resulted in the highest accumulation rate, ~ 227 mm/year, of all tested glasses. Noble metals that were added to high-Ni glass prevented large spinel crystals from forming and decreased the accumulation rate ~ 8.5 times. Adding ~5 wt% of Fe2O3 to the baseline glass resulted in a high number density of ~10-?m spinel crystals that remained suspended in the glass melt even after 17 days at 850°C. The accumulation rate of spinel crystals in high-chromia crucibles was only slightly higher compared with the accumulation rate in double crucibles. Only baseline glass exhibited about 2.6 times faster accumulation rate because of increased number of bigger crystals. These crystals were the result of glass enrichment with chromium that was leached out from the walls of high-chromia crucibles.

Matyas, Josef; Vienna, John D.; Kimura, Akihiko; Schaible, Micah J.; Tate, Rachel M.

2010-10-26

377

Effects of S/V on secondary phase formation on waste glasses  

SciTech Connect

Simulated West Valley high-level nuclear waste glass, WV205, was leached with and without buffered media in both deuterated and ordinary water at glass surface area to solution volumes (S/N) of 200--6000 m{sup {minus}1}. Examination of the glass surface after testing for 14 days indicated that the S/V-induced pH change plays a dominant role in the development of the altered surface layer and the secondary phases formed. The changes due to SN-induced pH determine the rate of surface layer formation, the element distribution in the surface layer, and possibly, the identities of the secondary phases. Changes due to SN-induced elemental concentration also influence glass reaction rate in terms of the layer thickness and the elemental distribution in the surface layers.

Feng, X.; Buck, E.C.; Bates, J.K.; Gong, M.; Dietz, N.L. [Argonne National Lab., IL (United States); Pegg, I.L. [Catholic Univ. of America, Washington, DC (United States). Vitreous State Lab.

1994-05-01

378

Survey of Potential Glass Compositions for the Immobilisation of the UK's Separated Plutonium Stocks  

SciTech Connect

The Nuclear Decommissioning Authority (NDA) has taken over ownership of the majority of the UK's separated civil plutonium stocks, which are expected to exceed 100 metric tons by 2010. Studies to technically underpin options development for the disposition of these stocks, for example by immobilization or re-use as fuel, are being carried out by Nexia Solutions on behalf of NDA. Three classes of immobilization matrices have been selected for investigation by means of previous studies and stakeholder dialogue: ceramic or crystalline waste-forms, storage MOx, and vitreous or glass-based waste-forms. This paper describes the preliminary inactive experimental program for the vitrification option, with results from a wide range of glass compositions along with conclusions on their potential use for plutonium immobilization. Following review, four glass systems were selected for preliminary investigation: borosilicate, lanthanide borosilicate, aluminosilicate and phosphate glasses. A broad survey of glass properties was completed in order to allow meaningful evaluation, e.g. glass formulation, waste loading, chemical durability, thermal properties, and viscosity. The program was divided into two parts, with silicate and phosphate glasses being investigated by Nexia Solutions and the Immobilisation Science Laboratory (ISL) at the University of Sheffield respectively. (authors)

Harrison, Mike T.; Scales, Charlie R. [Nexia Solutions Ltd, The British Technology Centre, Sellafield, Seascale, CA20 1PG (United Kingdom); Bingham, Paul A.; Hand, Russell J. [Immobilisation Science Laboratory, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD (United Kingdom)

2007-07-01

379

Nuclear Weapon  

MedlinePLUS

http://emergency.cdc.gov/radiation What is a nuclear weapon? A nuclear weapon is a device that uses ... radioactive and can contaminate anything it lands on. NUCLEAR WEAPON What are the main dangers of a nuclear ...

380

Glass Transition in Confined Geometry  

NASA Astrophysics Data System (ADS)

Extending mode-coupling theory, we elaborate a microscopic theory for the glass transition of liquids confined between two parallel flat hard walls. The theory contains the standard mode-coupling theory equations in bulk and in two dimensions as limiting cases and requires as input solely the equilibrium density profile and the structure factors of the fluid in confinement. We evaluate the phase diagram as a function of the distance of the plates for the case of a hard sphere fluid and obtain an oscillatory behavior of the glass transition line as a result of the structural changes related to layering.

Lang, Simon; Bo?an, Vitalie; Oettel, Martin; Hajnal, David; Franosch, Thomas; Schilling, Rolf

2010-09-01

381

Manufacturing unique glasses in space  

NASA Technical Reports Server (NTRS)

An air suspension melting technique is described for making glasses from substances which to date have been observed only in the crystalline condition. A laminar flow vertical wind tunnel was constructed for suspending oxide melts that were melted using the energy from a carbon dioxide laser beam. By this method it is possible to melt many high-melting-point materials without interaction between the melt and crucible material. In addition, space melting permits cooling to suppress crystal growth. If a sufficient amount of under cooling is accompanied by a sufficient increase in viscosity, crystallization will be avoided entirely and glass will result.

Happe, R. P.

1976-01-01

382

Glass-Derived Superconductive Ceramic  

NASA Technical Reports Server (NTRS)

Critical superconducting-transition temperature of 107.2 K observed in specimen made by annealing glass of composition Bi1.5Pb0.5Sr2Ca2Cu3Ox for 243 h at 840 degrees C. PbO found to lower melting temperature and viscosity of glass, possibly by acting as fluxing agent. Suggested partial substitution of lead into bismuth oxide planes of crystalline phase having Tc of 110 K stabilizes this phase and facilitates formation of it.

Bansal, Narottam P.; Farrell, D. E.

1992-01-01

383

Antiferromagnetic inclusions in lunar glass  

NASA Technical Reports Server (NTRS)

The magnetic susceptibility of eleven glass spherules from the Apollo 15, 16, and 17 fines and two specimens of a relatively large glass spherical shell were studied as a function of temperature from room temperature to liquid helium temperatures. All but one specimen showed the presence of antiferromagnetic inclusions. Closely spaced temperature measurements of the magnetic susceptibility below 77 K on five of the specimens showed antiferromagnetic temperature transitions (Neel transitions). With the exception of ilmenite in one specimen, these transitions did not correspond to any transitions in known antiferromagnetic compounds.

Thorpe, A. N.; Senftle, F. E.; Alexander, C.; Briggs, C.

1974-01-01

384

Antiferromagnetic inclusions in lunar glass  

USGS Publications Warehouse

The magnetic susceptibility of 11 glass spherules from the Apollo 15, 16, and 17 fines and two specimens of a relatively large glass spherical shell were studied as a function of temperature from room temperature to liquid helium temperatures. All but one specimen showed the presence of antiferromagnetic inclusions. Closely spaced temperature measurements of the magnetic susceptibility below 77 K on five of the specimens showed antiferromagnetic temperature transitions (Ne??el transitions). With the exception of ilmenite in one specimen, these transitions did not correspond to any transitions in known antiferromagnetic compounds. ?? 1974.

Thorpe, A.N.; Senftle, F.E.; Briggs, C.; Alexander, C.

1974-01-01

385

Structure glass technology : systems and applications  

E-print Network

Glass cannot compete with steel in terms of strength or durability, but it is the only structural material that offers the highly sought after qualities of translucency and transparency. The use of glass has evolved from ...

Leitch, Katherine K. (Katherine Kristen)

2005-01-01

386

High modulus high temperature glass fibers  

NASA Technical Reports Server (NTRS)

The search for a new high-modulus, high-temperature glass fiber involved the preparation of 500 glass compositions lying in 12 glass fields. These systems consisted primarily of low atomic number oxides and rare-earth oxides. Direct optical measurements of the kinetics of crystallization of the cordierite-rare earth system, for example, showed that the addition of rare-earth oxides decreased the rate of formation of cordierite crystals. Glass samples prepared from these systems proved that the rare-earth oxides made large specific contributions to the Young's modulus of the glasses. The best glasses have moduli greater than 21 million psi, the best glass fibers have moduli greater than 18 million psi, and the best glass fiber-epoxy resin composites have tensile strengths of 298,000 psi, compressive strengths of at least 220,000 psi, flexural strengths of 290,000 psi, and short-beam shear strengths of almost 17,000 psi.

Bacon, J. F.

1973-01-01

387

7 CFR 2902.30 - Glass cleaners.  

Code of Federal Regulations, 2011 CFR

...Designated Items § 2902.30 Glass cleaners. (a) Definition. Cleaning products designed specifically for use in cleaning glass surfaces, such as windows, mirrors, car windows, and computer monitors. (b) Minimum biobased...

2011-01-01

388

7 CFR 2902.30 - Glass cleaners.  

Code of Federal Regulations, 2010 CFR

...Designated Items § 2902.30 Glass cleaners. (a) Definition. Cleaning products designed specifically for use in cleaning glass surfaces, such as windows, mirrors, car windows, and computer monitors. (b) Minimum biobased...

2010-01-01

389

7 CFR 3201.30 - Glass cleaners.  

...Designated Items § 3201.30 Glass cleaners. (a) Definition. Cleaning products designed specifically for use in cleaning glass surfaces, such as windows, mirrors, car windows, and computer monitors. (b) Minimum biobased...

2014-01-01

390

7 CFR 3201.30 - Glass cleaners.  

Code of Federal Regulations, 2013 CFR

...Designated Items § 3201.30 Glass cleaners. (a) Definition. Cleaning products designed specifically for use in cleaning glass surfaces, such as windows, mirrors, car windows, and computer monitors. (b) Minimum biobased...

2013-01-01

391

7 CFR 3201.30 - Glass cleaners.  

Code of Federal Regulations, 2012 CFR

...Designated Items § 3201.30 Glass cleaners. (a) Definition. Cleaning products designed specifically for use in cleaning glass surfaces, such as windows, mirrors, car windows, and computer monitors. (b) Minimum biobased...

2012-01-01

392

Transparent oxyhalide glass and glass ceramics for gamma-ray detection  

NASA Astrophysics Data System (ADS)

Nuclear radiation detection is continuously becoming more important for today's society. Conventional scintillator based gamma-ray detectors use single crystal materials such as NaI:Tl, LaBr3:Ce, which provide excellent radiation detection properties, but suffer from their environment-related fluctuation, high cost and size limitation. The incorporation of nanophosphors or quantum dots (QD) into a transparent host matrix has been studied recently as a cost-saving alternative that may solve the scalability and stability problems while still providing considerable optical performance. In this work, a new glass based detecting material with promising gamma-ray detection performance is reported. Transparent alumino-silicate glasses containing cerium-doped gadolinium halide nanocrystals were prepared by a melt-quench method followed by annealing to form nanocrystal precipitates. Samples were cast and polished for optical and radiation characterization. The preliminary results indicated a similar gamma-ray detection efficiency compared to a conventional NaI:Tl detector and a gamma-ray peak resolution of ~27% at 662 KeV from some of these samples. By controlling elemental composition and ratio of the in-situ precipitated nanoparticles, radiation detection performance is expected to be improved.

Han, Chenlu; Barta, Meredith; Dorn, Max; Nadler, Jason; Rosson, Robert; Wagner, Brent; Kahn, Bernd; Kang, Zhitao

2011-09-01

393

IR, Raman, and NMR studies of the short-range structures of 0.5Na2S + 0.5[xGeS2 + (1-x)PS(5/2)] mixed glass-former glasses.  

PubMed

A nonlinear and nonadditive composition-dependent change of the ionic conductivity in mixed glass-former (MGF) glasses when one glass former, such as PS(5/2), is replaced by a second glass former, such as GeS2, at constant alkali modifier concentrations, such as Na2S, is known as the mixed glass-former effect (MGFE). Alkali ion conducting glasses are of particular interest for use as solid electrolytes in alkali-based all-solid-state batteries because sulfide amorphous materials have significantly higher alkali ion conductivities than their oxide glass counterparts. In this study of the ternary MGF system Na2S + GeS2 + PS(5/2), we report the careful structural characterization of these glasses using a combination of vibrational, infrared (IR), Raman, and nuclear magnetic resonance (NMR) spectroscopies. Our measurements of the 0.5Na2S + 0.5[xGeS2 + (1-x)PS(5/2)] MGF system show that this glass system exhibits a strongly negative MGFE and non-Arrhenius ionic conductivities. While this negative MGFE in the Na(+) ion conductivity makes these glasses less attractive for use in solid-state Na batteries, the structural origin of this effect is important to better understand the mechanisms of ion conduction in the glassy state. For these reasons, we have examined the structures of ternary 0.5Na2S + 0.5[xGeS2 + (1-x)PS(5/2)] glasses using Raman, IR, and (31)P MAS NMR spectroscopies. In these studies, it is found that the substitution of PS(5/2) by GeS2, that is, increasing x, leads to unequal sharing of the Na(+) in these glasses. Thus, in all MGF compositions, phosphorus groups are associated with a disproportionately larger fraction, f(Na(P)) > 0.5(1 - x), of the Na(+) ions while the germanium groups are found to be Na(+)-deficient relative to the total amount of Na(+) present in the glass, that is, f(Na(Ge)) < 0.5x. From the spectroscopic study of these glasses, a short-range order (SRO) structural model is developed for these glasses and is based on the germanium and phosphorus SRO groups in these glasses as a first step in understanding the unique negative MGFE and non-Arrhenius behavior in the Na(+) ion conductivity in these glasses. PMID:24447260

Bischoff, Christian; Schuller, Katherine; Dunlap, Nathan; Martin, Steve W

2014-02-20

394

Properties of a radioactive waste pellet package using cement-glass  

Microsoft Academic Search

This paper reports on radioactive waste slurry generated from nuclear power plants which is dried and compressed into pellets. These pellets are dropped in a polymer-impregnated concrete (PIC) barrier and solidified with cement-glass, which is a mixture of sodium silicate and cement. The mechanical strength of the PIC barrier is about three times higher than that of ordinary portland cement

K. Funabashi; K. Chino; M. Kikuchi; S. Horiuchi; H. Tsuchiya

1991-01-01

395

MANIFESTATION OF THE COLOR GLASS CONDENSATE IN PARTICLE PRODUCTION AT RHIC.  

SciTech Connect

In this paper we discuss the experimental signatures of the new form of nuclear matter--the Color Glass Condensate (CGC) in particle production at RHIC. We show that predictions for particle production in p(d)A and AA collisions derived from these properties are in agreement with data collected at RHIC.

TUCHIN,K.

2004-07-26

396

X-ray absorption studies of borosilicate glasses containing dissolved actinides or surrogates  

Microsoft Academic Search

The solubility of actinides and actinide surrogates in a nuclear borosilicate glass was studied with cerium, hafnium, neodymium, thorium and plutonium. Cerium is a possible surrogate for tetravalent and trivalent actinides such as plutonium, hafnium for tetravalent actinide such as thorium, and neodymium for trivalent actinides such as curium or americium. X-ray absorption spectroscopy was used to obtain data on

C Lopez; X Deschanels; C Den Auwer; J-N Cachia; S Peuget; J-M Bart

2005-01-01

397

X-Ray Absorption Studies of Borosilicate Glasses Containing Dissolved Actinides Or Surrogates  

Microsoft Academic Search

The solubility of actinides and actinide surrogates in a nuclear borosilicate glass was studied with cerium, hafnium, neodymium, thorium and plutonium. Cerium is a possible surrogate for tetravalent and trivalent actinides such as plutonium, hafnium for tetravalent actinide such as thorium, and neodymium for trivalent actinides such as curium or americium. X-ray absorption spectroscopy was used to obtain data on

C. Lopez; X. Deschanels; C. Den Auwer; J.-N. Cachia; S. Peuget; J.-M. Bart

2006-01-01

398

A spinning thermometer to monitor microwave heating and glass transitions in dynamic  

E-print Network

A spinning thermometer to monitor microwave heating and glass transitions in dynamic nuclear in potassium bromide (KBr) allows one to deter- mine the temperature of a spinning sample. We propose to adapt the original design by using a compact KBr tablet placed at the bottom of the magic angle spinning rotor

399

Alice through Looking Glass after Looking Glass: The Mathematics of Mirrors and Kaleidoscopes  

Microsoft Academic Search

1. ALICE AND THE MIRRORS. Let us imagine that Lewis Carroll stopped con- densing determinants long enough to write a third Alice book called Alice Through Looking Glass After Looking Glass. The book opens with Alice in her chamber in front of a peculiar cone-shaped arrangement of three looking glasses. She steps through one of the looking glasses and finds

Roe Goodman

2004-01-01

400

Crystallization of a barium-aluminosilicate glass  

NASA Technical Reports Server (NTRS)

The crystallization of a celsian glass composition was investigated as a possible high-temperature ceramic matrix material. Heat treatments invariably resulted in crystallization of the hexaclesian phase unless a flux, such as lithia, was added or a nucleating agent used (e.g., celsian seeds). TEM analysis revealed complex microstructures. Glasses with Mo additions contained hexacelsian, mullite, and an Mo-rich glass. Li2O additions stabilized celsian but mullite and Mo-rich glass were still present.

Drummond, C. H., III; Lee, W. E.; Bansal, N. P.; Hyatt, M. J.

1989-01-01

401

Friction behavior of glass and metals in contact with glass in various environments  

NASA Technical Reports Server (NTRS)

Sliding friction experiments have been conducted for heat-resistant glass and metals in contact with glass. These experiments were conducted in various environments including vacuum, moist air, dry air, octane, and stearic acid in hexadecane. Glass exhibited a higher friction force in moist air than it did in vacuum when in sliding contact with itself. The metals, aluminum, iron, and gold, all exhibited the same friction coefficient when sliding on glass in vacuum as glass sliding on glass. Gold-to-glass contacts were extremely sensitive to the environment despite the relative chemical inertness of gold.

Buckley, D. H.

1973-01-01

402

Heating-induced glass-glass and glass-liquid transformations in computer simulations of water  

SciTech Connect

Water exists in at least two families of glassy states, broadly categorized as the low-density (LDA) and high-density amorphous ice (HDA). Remarkably, LDA and HDA can be reversibly interconverted via appropriate thermodynamic paths, such as isothermal compression and isobaric heating, exhibiting first-order-like phase transitions. We perform out-of-equilibrium molecular dynamics simulations of glassy water using the ST2 model to study the evolution of LDA and HDA upon isobaric heating. Depending on pressure, glass-to-glass, glass-to-crystal, glass-to-vapor, as well as glass-to-liquid transformations are found. Specifically, heating LDA results in the following transformations, with increasing heating pressures: (i) LDA-to-vapor (sublimation), (ii) LDA-to-liquid (glass transition), (iii) LDA-to-HDA-to-liquid, (iv) LDA-to-HDA-to-liquid-to-crystal, and (v) LDA-to-HDA-to-crystal. Similarly, heating HDA results in the following transformations, with decreasing heating pressures: (a) HDA-to-crystal, (b) HDA-to-liquid-to-crystal, (c) HDA-to-liquid (glass transition), (d) HDA-to-LDA-to-liquid, and (e) HDA-to-LDA-to-vapor. A more complex sequence may be possible using lower heating rates. For each of these transformations, we determine the corresponding transformation temperature as function of pressure, and provide a P-T “phase diagram” for glassy water based on isobaric heating. Our results for isobaric heating dovetail with the LDA-HDA transformations reported for ST2 glassy water based on isothermal compression/decompression processes [Chiu et al., J. Chem. Phys. 139, 184504 (2013)]. The resulting phase diagram is consistent with the liquid-liquid phase transition hypothesis. At the same time, the glass phase diagram is sensitive to sample preparation, such as heating or compression rates. Interestingly, at least for the rates explored, our results suggest that the LDA-to-liquid (HDA-to-liquid) and LDA-to-HDA (HDA-to-LDA) transformation lines on heating are related, both being associated with the limit of kinetic stability of LDA (HDA)

Chiu, Janet; Giovambattista, Nicolas [Department of Physics, Brooklyn College of the City University of New York, Brooklyn, New York 11210 (United States)] [Department of Physics, Brooklyn College of the City University of New York, Brooklyn, New York 11210 (United States); Starr, Francis W. [Department of Physics, Wesleyan University, Middletown, Connecticut 06459 (United States)] [Department of Physics, Wesleyan University, Middletown, Connecticut 06459 (United States)

2014-03-21

403

Modeling the glass forming ability of metals  

Microsoft Academic Search

A design protocol for the discovery of novel metallic glass compositions has been developed using a multi-model approach. By using a series of modeling criteria, all aspects of vitrification in metals can be simultaneously analyzed, and optimum compositions for metallic glass formation can be accurately determined. The modeling tools used focus on three aspects common among good glass forming alloy:

Justin Lee Cheney

2007-01-01

404

Turning of glass with abrasive waterjet  

Microsoft Academic Search

This article reports research results on abrasive waterjet (AWJ) turning of glass. Glass rods, 25 mm in diameter, were turned by using AWJ to investigate the effects of several process parameters on the surface quality of the machined glass surfaces. The parameters studied are rotational speed, stand-off distance, water pressure, nozzle traverse speed, and abrasive flow rate. The results were also

Z. W. Zhong; Z. Z. Han

2002-01-01

405

Field Assisted Glass-Metal Sealing  

Microsoft Academic Search

A new process is described which permits the sealing of metals to glass and other insulators at temperatures well below the softening point of the glass. Sealing is accomplished in about 1 min by applying a dc voltage in excess of a few hundred volts between the glass and the metal in such a way that the former is at

George Wallis; Daniel I. Pomerantz

1969-01-01

406

History of the Glass Industry Committee  

Microsoft Academic Search

THE IEEE Glass Industry Committee history parallels the glass industry developments of the past quarter century. During this period, process improvements, increased computer use, and sophisticated control developments, documented by IEEE papers, led the industry to its present position. The stimulation of glass industry electrical engineers by IEEE participation, encouraged by individual corporate management, resulted in the improvement of the

Robert L. Smith

1984-01-01

407

Modeling gain saturation in neodymium laser glasses  

Microsoft Academic Search

Gain saturation in neodymium laser glasses was modeled using a simplified treatment of the spectroscopic inhomogeneities and experimental parameters obtained from broadband- and laser-excited fluorescence spectroscopy. The predicted large-signal gain behavior for two silicate and two phosphate glasses agrees with measured gain saturation within the experimental uncertainties. The results are extended to treat saturation of other Nd-doped glasses.

D. W. Hall; M. J. Weber

1984-01-01

408

Grinding Glass Disks On A Belt Sander  

NASA Technical Reports Server (NTRS)

Small machine attached to table-top belt sander makes possible to use belt sander to grind glass disk quickly to specified diameter within tolerance of about plus or minus 0.002 in. Intended to be used in place of production-shop glass grinder. Held on driveshaft by vacuum, glass disk rotated while periphery ground by continuous sanding belt.

Lyons, James J., III

1995-01-01

409

Diffusion in metallic glasses and supercooled melts  

Microsoft Academic Search

Amorphous metallic alloys, also called metallic glasses, are of considerable technological importance. The metastability of these systems, which gives rise to various rearrangement processes at elevated temperatures, calls for an understanding of their diffusional behavior. From the fundamental point of view, these metallic glasses are the paradigm of dense random packing. Since the recent discovery of bulk metallic glasses it

Franz Faupel; Werner Frank; Michael-Peter Macht; Helmut Mehrer; Volkmar Naundorf; Klaus Rätzke; Herbert R. Schober; Suman K. Sharma; Helmar Teichler

2003-01-01

410

The properties of glass resistive plate chambers made of different glasses  

NASA Astrophysics Data System (ADS)

Glass resistive plate chambers (GRPCs) have been proposed as the basic element for the JUNO top tracker detector. With good uniform performance and low cost, GRPCs are well suited for large area experiments. Glass RPCs used in underground experiments require specially designed cassette and gas flow systems, since the glass is fragile and easily corroded by acid generated by water entering the gas-filled chamber. High-strength and chemical-resistant glasses have been proposed for underground experiments. We present here the test results of four GRPC chambers made of different glasses: normal thin glass, two high-strength glasses, and a chemical-resistant glass. The chemical-resistant and high-strength glasses have good surface quality, but their volume resistivities are higher. Higher resistivities lead to a higher required voltage to reach plateau operation, meaning that these glasses can only work in a very low rate experiment.

Han, R.; Shi, Z.; Laktineh, I.; Chen, Y.; Zhang, J.; Qian, S.; Ning, Z.

2014-09-01

411

Analysis of early medieval glass beads - Glass in the transition period  

NASA Astrophysics Data System (ADS)

Glass beads from graves excavated in Slovenia and dated archaeologically to the 7th-10th century AD were analysed by the combined PIXE-PIGE method. The results indicate two groups of glass; natron glass made in the Roman tradition and glass made with alkalis from the ash of halophytic plants, which gradually replaced natron glass after c. 800 AD. The alkalis used in the second group of glass seem to be in close relation to a variant of the Venetian white glass that appeared several centuries later. The origin of this glass may be traced to glass production in Mesopotamia and around the Aral Sea. All the mosaic beads with eye decoration, as well as most of the drawn-segmented and drawn-cut beads analysed, are of plant-ash glass, which confirms their supposed oriental origin.

Šmit, Žiga; Knific, Timotej; Jezeršek, David; Isteni?, Janka

2012-05-01

412

Yielding of binary colloidal glasses  

E-print Network

The rheological response, in particular the non-linear response, to oscillatory shear is experimentally investigated in colloidal glasses. The glasses are highly concentrated binary hard-sphere mixtures with relatively large size disparities. For a size ratio of 0.2, a strong reduction of the normalized elastic moduli, the yield strain and stress and, for some samples, even melting of the glass to a fluid is observed upon addition of the second species. This is attributed to the more efficient packing, as indicated by the shift of random close packing to larger total volume fractions. This leads to an increase in free volume which favours cage deformations and hence a loosening of the cage. Cage deformations are also favoured by the structural heterogeneity introduced by the second species. For a limited parameter range, we furthermore found indications of two-step yielding, as has been reported previously for attractive glasses. In samples containing spheres with more comparable sizes, namely a size ratio of 0.38, the cage seems less distorted and structural heterogeneities on larger length scales seem to become important. The limited structural changes are reflected in only a small reduction of the moduli, yield strain and stress.

T. Sentjabrskaja; E. Babaliari; J. Hendricks; M. Laurati; G. Petekidis; S. U. Egelhaaf

2013-01-31

413

Glass-to-Metal Seals  

Microsoft Academic Search

The problems of sealing are adhesion and strain. The simplest, but perhaps not the only means of adhesion is a firm layer of metal oxide. Strains can be avoided if, and only if the thermal expansions of metal and glass are the same. This postulate is thoroughly tested. Equations are derived for the stresses in cylindrical seals, in terms of

Albert W. Hull; E. E. Burger

1934-01-01

414

Inhomogeneous deformation in metallic glasses  

Microsoft Academic Search

The present study provides a theoretical framework for the inhomogeneous deformation in metallic glasses. The free volume concentration is adopted as the order parameter, which is a function of position and time. The three processes that can change the local free volume concentration are diffusion, annihilation, and stress-driven creation. The rate functions for free volume generation and plastic flow depend

R. Huang; Z. Suo; J. H. Prevost; W. D. Nix

2002-01-01

415

Structure and properties of strontium-doped phosphate-based glasses  

PubMed Central

Owing to similarity in both ionic size and polarity, strontium (Sr2+) is known to behave in a comparable way to calcium (Ca2+), and its role in bone metabolism has been well documented as both anti-resorptive and bone forming. In this study, novel quaternary strontium-doped phosphate-based glasses, containing 1, 3 and 5?mol% SrO, were synthesized and characterized. 31P magic angle spinning (MAS) nuclear magnetic resonance results showed that, as the Sr2+ content is increased in the glasses, there is a slight increase in disproportionation of Q2 phosphorus environments into Q1 and Q3 environments. Moreover, shortening and strengthening of the phosphorus to bridging oxygen distance occurred as obtained from FTIR. The general broadening of the spectral features with Sr2+ content is most probably due to the increased variation of the phosphate–cation bonding interactions caused by the introduction of the third cation. This increased disorder may be the cause of the increased degradation of the Sr-containing glasses relative to the Sr-free glass. As confirmed from elemental analysis, all Sr-containing glasses showed higher Na2O than expected and this also could be accounted for by the higher degradation of these glasses compared with Sr-free glasses. Measurements of surface free energy (SFE) showed that incorporation of strontium had no effect on SFE, and samples had relatively higher fractional polarity, which is not expected to promote high cell activity. From viability studies, however, the incorporation of Sr2+ showed better cellular response than Sr2+-free glasses, but still lower than the positive control. This unfavourable cellular response could be due to the high degradation nature of these glasses and not due to the presence of Sr2+. PMID:18826914

Abou Neel, Ensanya A.; Chrzanowski, Wojciech; Pickup, David M.; O'Dell, Luke A.; Mordan, Nicola J.; Newport, Robert J.; Smith, Mark E.; Knowles, Jonathan C.

2008-01-01

416

Dynamics of glass relaxation at room temperature.  

PubMed

The problem of glass relaxation under ambient conditions has intrigued scientists and the general public for centuries, most notably in the legend of flowing cathedral glass windows. Here we report quantitative measurement of glass relaxation at room temperature. We find that Corning® Gorilla® Glass shows measurable and reproducible relaxation at room temperature. Remarkably, this relaxation follows a stretched exponential decay rather than simple exponential relaxation, and the value of the stretching exponent (?=3/7) follows a theoretical prediction made by Phillips for homogeneous glasses. PMID:23848901

Welch, Roger C; Smith, John R; Potuzak, Marcel; Guo, Xiaoju; Bowden, Bradley F; Kiczenski, T J; Allan, Douglas C; King, Ellyn A; Ellison, Adam J; Mauro, John C

2013-06-28

417

Dynamics of Glass Relaxation at Room Temperature  

NASA Astrophysics Data System (ADS)

The problem of glass relaxation under ambient conditions has intrigued scientists and the general public for centuries, most notably in the legend of flowing cathedral glass windows. Here we report quantitative measurement of glass relaxation at room temperature. We find that Corning® Gorilla® Glass shows measurable and reproducible relaxation at room temperature. Remarkably, this relaxation follows a stretched exponential decay rather than simple exponential relaxation, and the value of the stretching exponent (?=3/7) follows a theoretical prediction made by Phillips for homogeneous glasses.

Welch, Roger C.; Smith, John R.; Potuzak, Marcel; Guo, Xiaoju; Bowden, Bradley F.; Kiczenski, T. J.; Allan, Douglas C.; King, Ellyn A.; Ellison, Adam J.; Mauro, John C.

2013-06-01

418

Induced charge signal of a glass RPC detector  

NASA Astrophysics Data System (ADS)

A gas detector glass resistivity plate chamber (GRPC) is proposed for use in the hadron calorimeter (HCAL). The read-out system is based on a semi-digital system and, therefore, the charge information from GRPC is needed. To better understand the charge that comes out from the GRPC, we started from a cosmic ray test to get the charge distribution. We then studied the induced charge distribution on the collection pad. After successfully comparing it with the prototype beam test data at CERN (European Council for Nuclear Research), the process was finally implanted into the Geant4 based simulation for future study.

Han, Ran

2014-04-01

419

Nuclear diffractive structure functions at high energies  

E-print Network

A future high-energy electron-ion collider would explore the non-linear weakly-coupled regime of QCD, and test the Color Glass Condensate (CGC) approach to high-energy scattering. Hard diffraction in deep inelastic scattering off nuclei will provide many fundamental measurements. In this work, the nuclear diffractive structure function F_{2,A}^D is predicted in the CGC framework, and the features of nuclear enhancement and suppression are discussed.

C. Marquet; H. Kowalski; T. Lappi; R. Venugopalan

2008-05-30

420

Nuclear waste programs; Semiannual progress report, October 1991--March 1992  

SciTech Connect

This document reports on the work done by the Nuclear Waste Programs of the Chemical Technology Division (CMT), Argonne National Laboratory, in the period October 1991-March 1992. In these programs, studies are underway on the performance of waste glass and spent fuel in projected nuclear repository conditions to provide input to the licensing of the nation`s high-level waste repositories

Bates, J.K.; Bradley, C.R.; Buck, E.C.; Dietz, N.L.; Ebert, W.L.; Emery, J.W.; Feng, X.; Finn, P.A.; Gerding, T.J.; Hoh, J.C. [and others

1993-11-01

421

Nuclear Waste Programs semiannual progress report, April--September 1992  

SciTech Connect

This document reports on the work done by the Nuclear Waste Programs of the Chemical Technology Division (CMT), Argonne National Laboratory, in the period April--September 1992. In these programs, studies are underway on the performance of waste glass and spent fuel in projected nuclear repository conditions to provide input to the licensing of the nation`s high-level waste repositories.

Bates, J.K.; Bradley, C.R.; Buck, E.C. [and others

1994-05-01

422

PREFACE: International Seminar on Science and Technology of Glass Materials (ISSTGM-2009)  

NASA Astrophysics Data System (ADS)

The progress of the human race is linked with the development of new materials and also the values they acquired in the course of time. Though the art of glass forming has been known from Egyptian civilization, the understanding and use of these glasses for technological applications only became possible once the structural aspects were revealed by the inspiring theories proposed by William H Zachariasen. Glass and glass ceramics have become the essential materials for modern technology. The applications of these materials are wide and cover areas such as optical communication, laser host, innovative architecture, bio-medical, automobile and space technology. As we master the technology, we must also learn to use it judiciously and for the overall development of all in this global village. The International Seminar on Science and Technology of Glass Materials (ISSTGM-2009) is organized to bring together scientists, academia and industry in order to discuss various aspects of the technology and to inspire young scholars to take up fruitful research. Various topics such as glass formation and glass-ceramics, glass structure, applications of glass and glass ceramics in nuclear waste management, radiation dosimetry, electronics and information technology, biotechnological applications, bulk metallic glasses, glasses containing nano-particles, hybrid glasses, novel glasses and applications in photonics, Non-linear optics and energy generation were discussed. In this volume, 59 research articles covering 18 invited talks, 10 oral presentations and 31 poster presentations are included. We hope these will serve as a valuable resource to all the scientists and scholars working with glass materials. Acharya Nagarjuna University, established in 1976, is named after the great Buddhist preceptor and philosopher, Acharya Nagarjuna, who founded a university on the banks of river Krishna some centuries ago. The University is situated between Vijayawada and Guntur, the famous commercial and academic centers of Andhra Pradesh, India. The Departments of Physics of Acharya Nagarjuna University and the Nuzvid Campus have existed since the inception of the University. For the past decade and a half, these Departments have been actively involved in research on glass materials. More than 200 research articles have been published by staff members of these departments exclusively on glass materials. A number of Major Research Projects are being carried out by the staff members of these Departments. The organizing committee is indebted to all the scientists and scholars for their active participation in the seminar and their contribution to this proceedings. The committee expresses its gratitude to the authorities of Acharya Nagarjuna University (The Vice-Chancellor, The Rector and The Registrar), Department of Atomic Energy, Board of Research in Nuclear Sciences, Department of Science and Technology, Council of Scientific and Industrial Research, Defence Research and Development Organization and AP State Council of Science and Technology for their financial support. The committee thanks the IOP: Conference Series publisher for publishing this proceedings which added value to the seminar. Professor N Veeraiah Convener and Editor-in-Chief Professor D Krishna Rao Co-Convener

Veeraiah, N.

2009-07-01

423

Relations between a liquid and its glasses  

SciTech Connect

Ideas developed to describe the simulated glass transition in simple models, like hard spheres, are applied to real materials in which temperature, rather than density, is the important variable. The free energy of a liquid is expressed in terms of the free energy of all the glasses that it samples. The assumption that all glasses of the same substance have the same heat capacity allows an estimate of the number of glasses that it can form and the distribution of their enthalpies, from heat capacity measurements on the liquid and an experimental glass. The results suggest a thermodynamic glass transition underlying the experimental kinetic transition. The same ideas explain the relation between thermodynamic and kinetic measures of fragility in liquids, and they show that the fragility of a liquid is directly related to the total number of glasses that the material can form.

Speedy, R.J. [Princeton Univ., NJ (United States). Dept. of Chemical Engineering] [Princeton Univ., NJ (United States). Dept. of Chemical Engineering

1999-05-20

424

glass chemistry: structure-property relationships  

NASA Astrophysics Data System (ADS)

Pyrex® glass was one of the first commercial boroaluminosilicate glass compositions, selected in 1915 from thousands of compositions due to its ability to sustain mechanical and thermal shock. While the microscopic structure of Pyrex® glass has recently been investigated, the microscopic origins of its macroscopic properties are not well understood, i.e., the atomic scale foundation of the original empirical invention of Pyrex® glass has yet to be established. In this work, we have tackled this problem by investigating the effects of varying Si/Al and Na/B ratios on the boron and aluminum speciation and a range of physical and rheological properties in the Pyrex® glass family. We show that the canonical Pyrex® boroaluminosilicate composition is indeed optimal for attaining relatively high values of glass transition temperature and elastic moduli and a low coefficient of thermal expansion, while simultaneously maintaining a high glass-forming ability.

Smedskjaer, Morten M.; Youngman, Randall E.; Mauro, John C.

2014-08-01

425

Neutron diffraction studies of natural glasses  

SciTech Connect

A neutron diffraction investigation has been carried out of the structures of several naturally occurring glasses, viz. Libyan Desert glass, a Fulgurite, Wabar glass, Lechatelierite from Canon Diablo, a Tektite, Obsidian (3 samples), and Macusani glass. Libyan Desert sand has also been examined, together with crystalline ..cap alpha..-quartz and ..cap alpha..-cristobalite. A comparison of data for the natural glasses and synthetic vitreous silica (Spectrosil B) in both reciprocal and real space allows a categorisation into Silicas, which closely resemble synthetic vitreous silica, and Silicates, for which the resemblance to silica is consistently less striking. The data support the view that Libyan Desert glass and sand have a common origin, while the Tektite has a structure similar to that of volcanic glasses.

Wright, A.C.; Erwin Desa, J.A.; Weeks, R.A.; Sinclair, R.N.; Bailey, D.K.

1983-08-01

426

Pressurized heat treatment of glass ceramic  

DOEpatents

A method of producing a glass-ceramic having a specified thermal expansion value is disclosed. The method includes the step of pressurizing the parent glass material to a predetermined pressure during heat treatment so that the glass-ceramic produced has a specified thermal expansion value. Preferably, the glass-ceramic material is isostatically pressed. A method for forming a strong glass-ceramic to metal seal is also disclosed in which the glass-ceramic is fabricated to have a thermal expansion value equal to that of the metal. The determination of the thermal expansion value of a parent glass material placed in a high-temperature environment is also used to determine the pressure in the environment.

Kramer, D.P.

1984-04-19

427

Recirculation bubbler for glass melter apparatus  

DOEpatents

A gas bubbler device provides enhanced recirculation of molten glass within a glass melter apparatus. The bubbler device includes a tube member disposed within a pool of molten glass contained in the melter. The tube member includes a lower opening through which the molten glass enters and upper slots disposed close to (above or below) the upper surface of the pool of molten glass and from which the glass exits. A gas (air) line is disposed within the tube member and extends longitudinally thereof. A gas bubble distribution device, which is located adjacent to the lower end of the tube member and is connected to the lower end of the gas line, releases gas through openings therein so as to produce gas bubbles of a desired size in the molten glass and in a distributed pattern across the tube member.

Guerrero, Hector (Evans, GA); Bickford, Dennis (Folly Beach, SC)

2007-06-05

428

Glasses, ceramics, and composites from lunar materials  

NASA Technical Reports Server (NTRS)

A variety of useful silicate materials can be synthesized from lunar rocks and soils. The simplest to manufacture are glasses and glass-ceramics. Glass fibers can be drawn from a variety of basaltic glasses. Glass articles formed from titania-rich basalts are capable of fine-grained internal crystallization, with resulting strength and abrasion resistance allowing their wide application in construction. Specialty glass-ceramics and fiber-reinforced composites would rely on chemical separation of magnesium silicates and aluminosilicates as well as oxides titania and alumina. Polycrystalline enstatite with induced lamellar twinning has high fracture toughness, while cordierite glass-ceramics combine excellent thermal shock resistance with high flexural strengths. If sapphire or rutile whiskers can be made, composites of even better mechanical properties are envisioned.

Beall, George H.

1992-01-01

429

Combinatorial development of bulk metallic glasses.  

PubMed

The identification of multicomponent alloys out of a vast compositional space is a daunting task, especially for bulk metallic glasses composed of three or more elements. Despite an increasing theoretical understanding of glass formation, bulk metallic glasses are predominantly developed through a sequential and time-consuming trial-and-error approach. Even for binary systems, accurate quantum mechanical approaches are still many orders of magnitude away from being able to simulate the relatively slow kinetics of glass formation. Here, we present a high-throughput strategy where ?3,000 alloy compositions are fabricated simultaneously and characterized for thermoplastic formability through parallel blow forming. Using this approach, we identified the composition with the highest thermoplastic formability in the glass-forming system Mg-Cu-Y. The method provides a versatile toolbox for unveiling complex correlations of material properties and glass formation, and should facilitate a drastic increase in the discovery rate of metallic glasses. PMID:24728462

Ding, Shiyan; Liu, Yanhui; Li, Yanglin; Liu, Ze; Sohn, Sungwoo; Walker, Fred J; Schroers, Jan

2014-05-01

430

Laser cleaving of glass fibers and glass fiber arrays  

Microsoft Academic Search

An ultraviolet (UV)-excimer-laser-based cleaving procedure for silica fiber has been developed that enables automated cleaving for high-volume production of fiber-optic assemblies. A selective ablation of the glass in the form of a small rectangular cavity serves as a fracture initiator when the fiber is put under stress. The position of the UV-excimer-laser-induced scratch is very precise. The system provides high-quality

G. Van Steenberge; Peter Geerinck; S. Van Put; J. Watte; Heidi Ottevaere; Hugo Thienpont; P. Van Daele

2005-01-01

431

Nuclear sabotage  

Microsoft Academic Search

The psychology of attacks on nuclear facilities is considered. The following information is given in tabular form: attacks on nuclear installations and facilities; hoaxes and threats to nuclear installations or facilities; vandalism and sabotage at nuclear facilities; security breaches at nuclear installations and facilities; and U.S. companies fined for non-compliance with security regulations. (LK)

1976-01-01

432

Probing the glass transition from structural and vibrational properties of zero-temperature glasses  

E-print Network

We find that the density dependence of the glass transition temperature of Lennard-Jones (LJ) and Weeks-Chandler-Andersen (WCA) systems can be predicted from properties of the zero-temperature ($T=0$) glasses. Below a crossover density $\\rho_s$, LJ and WCA glasses show different structures, leading to different vibrational properties and consequently making LJ glasses more stable with higher glass transition temperatures than WCA ones. Above $\\rho_s$, structural and vibrational quantities of the $T=0$ glasses show scaling collapse. From scaling relations and dimensional analysis, we predict a density scaling of the glass transition temperature, in excellent agreement with simulation results. We also propose an empirical expression of the glass transition temperature using structural and vibrational properties of the $T=0$ glasses, which works well over a wide range of densities.

Lijin Wang; Ning Xu

2014-02-10

433

Spin glasses on the hypercube  

NASA Astrophysics Data System (ADS)

We present a mean field model for spin glasses with a natural notion of distance built in, namely, the Edwards-Anderson model on the diluted D -dimensional unit hypercube in the limit of large D . We show that finite D effects are strongly dependent on the connectivity, being much smaller for a fixed coordination number. We solve the nontrivial problem of generating these lattices. Afterward, we numerically study the nonequilibrium dynamics of the mean field spin glass. Our three main findings are the following: (i) the dynamics is ruled by an infinite number of time sectors, (ii) the aging dynamics consists of the growth of coherent domains with a nonvanishing surface-volume ratio, and (iii) the propagator in Fourier space follows the p4 law. We study as well the finite D effects in the nonequilibrium dynamics, finding that a naive finite size scaling ansatz works surprisingly well.

Fernández, L. A.; Martin-Mayor, V.; Parisi, G.; Seoane, B.

2010-04-01

434