scholarly journals Glass as a Waste Form for the Immobilization of Plutonium

1995 ◽  
Vol 412 ◽  
Author(s):  
J. K. Bates ◽  
A. J. G. Ellison ◽  
J. W. Emery ◽  
J. C. Hoh
Keyword(s):  
Silicate Glass ◽  
Neutron Absorber ◽  
Test Conditions ◽  
Rate Of Reaction ◽  
Processing Facility ◽  
Surface Alteration ◽  
Reaction With Water ◽  
Tin Silicate ◽  
Static Corrosion

AbstractSeveral alternatives for disposal of surplus plutonium are being considered. One method is incorporating Pu into glass and in this paper we discuss the development and corrosion behavior of an alkali-tin-silicate glass and update results in testing Pu doped Defense Waste Processing Facility (DWPF) reference glasses. The alkali-tin-silicate glass was engineered to accommodate a high Pu loading and to be durable under conditions likely to accelerate glass reaction. The glass dissolves about 7 wt% Pu together with the neutron absorber Gd, and under test conditions expected to accelerate the glass reaction with water, is resistant to corrosion. The Pu and the Gd are released from the glass at nearly the same rate in static corrosion tests in water, and are not segregated into surface alteration phases when the glass is reacted in water vapor. Similar results for the behavior of Pu and Gd are found for the DWPF reference glasses, although the long-term rate of reaction for the reference glasses is more rapid than for the alkalitin-silicate glass.

scholarly journals The Release of Technetium from Defense Waste Processing Facility Glasses

1995 ◽  
Vol 412 ◽  
Author(s):  
W. L. Ebert ◽  
S. F. Wolf ◽  
J. K. Bates
Keyword(s):  
Glass Surface ◽  
Laboratory Tests ◽  
Water Solution ◽  
Waste Processing ◽  
Glass Dissolution ◽  
Test Conditions ◽  
Processing Facility ◽  
Nitrite Nitrate ◽  
Solution Volume

AbstractLaboratory tests are being conducted using two radionuclide-doped Defense Waste Processing Facility (DWPF) glasses (referred to as SRL 131A and SRL 202A) to characterize the effects of the glass surface area/solution volume (SN) ratio on the release and disposition of Tc and several actinide elements. Tests are being conducted at 90°C in a tuff ground water solution at S/V ratios of 10, 2000, and 20,000 m−1 and have been completed through 1822 days. The formation of certain alteration phases in tests at 2000 and 20,000 m−1 results in an increase in the dissolution rates of both glasses. The release of Tc parallels that of B and Na under most test conditions and its release increases when alteration phases form. However, in tests with SRL 202A glass at 20,000 m−1, the Tc concentration in solution decreases coincidentally with an increase in the nitrite/nitrate ratio that indicates a decrease in the solution Eh. This may have occurred due to radiolysis, glass dissolution, the formation of alteration phases, or vessel interactions. Technetium that was reduced from Tc(VII) to Tc(IV) may have precipitated, though the amount of Tc was too low to detect any Tc-bearing phases. These results show the importance of conducting long-term tests with radioactive glasses to characterize the behavior of radionuclides, rather than relying on the observed behavior of nonradioactive surrogates.

Examination of some microbiological and biochemical parameters and tests of product quality used in a long-term fertilization trial

1998 ◽  
Vol 13 (3) ◽  
pp. 138-144 ◽  
Author(s):  
Joachim Raupp
Keyword(s):  
Food Storage ◽  
Optimal Conditions ◽  
Social Psychological ◽  
Optimal Test ◽  
Test Conditions ◽  
Environmental Criteria ◽  
Degradation Tests ◽  
Reliable Parameter ◽  
Chemical Contents

AbstractOn the basis of investigations with samples from a fertilization trial started in 1980, some parameters of food storage ability are evaluated. Microbial infestation of the product during incubation seems to be the most reliable parameter, but the circumstances of infestation and the optimal test conditions are unknown. There are no reliable correlations among the results of degradation tests, storage tests under optimal conditions, and chemical contents of the product. The concept of product vitality (a product-oriented quality referring to a product full of vigor) is based on results of degradation tests. Ultimately, however, food quality standards are based on human priorities (human-oriented). Therefore, not only product characteristics, but also social, psychological, and environmental criteria should be considered.

Photosensitive erbium doped tin-silicate glass

2002 ◽  
Vol 311 (3) ◽  
pp. 217-222 ◽  
Author(s):  
N Chiodini ◽  
A Paleari ◽  
G Spinolo ◽  
A Chiasera ◽  
M Ferrari ◽  
...  
Keyword(s):  
Silicate Glass ◽  
Erbium Doped ◽  
Tin Silicate

Tracing Fluid Flow in Flooded Chalk under Long Term Test Conditions

2013 ◽  
Author(s):  
R.I. Korsnes ◽  
U. Zimmermann ◽  
M.V. Madland ◽  
S.A.R. Bertolino ◽  
T. Hildebrand-Habel ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Test Conditions

Ocular Surface Alteration after Long-term Treatment with an Antiglaucomatous Drug

Ophthalmology ◽  
1992 ◽  
Vol 99 (7) ◽  
pp. 1082-1088 ◽  
Author(s):  
José M. Herreras ◽  
J. Carlos Pastor ◽  
Margarita Calonge ◽  
Victor M. Asensio
Keyword(s):  
Ocular Surface ◽  
Term Treatment ◽  
Long Term Treatment ◽  
Surface Alteration

Nd- and Ce-doped ceramic-glass composites: chemical durability under aqueous conditions and Surface alteration in a moist clay medium at 90°C

2000 ◽  
Vol 663 ◽  
Author(s):  
P.J. Mcglinn ◽  
T. Advocat ◽  
E. Loi ◽  
G. Leturcq ◽  
J.P. Mestre
Keyword(s):  
Chemical Durability ◽  
Powdered Sample ◽  
Leaching Behavior ◽  
Glass Composites ◽  
Geological Repository ◽  
Trivalent Actinides ◽  
Surface Alteration ◽  
Ceramic Glass ◽  
Aqueous Conditions

ABSTRACTZirconolite-glass and sphene -glass specimens, doped with REE as simulants for trivalent actinides, were leached under two conditions. The first was a solubility test using a powdered sample in deionized water at an SA/V ratio of 200 cm−1, to examine the long-term leaching behavior of the composite materials. The other test was carried out in the presence of moist clay, to assess the degree of surface alteration of the composites in the presence of potential geological repository materials. Both tests were carried out at 90°C.

scholarly journals Glass-Sensors: Assessment of Complex Corrosive Stresses in Conservation Research

1990 ◽  
Vol 185 ◽  
Author(s):  
Dieter R. Fuchs ◽  
Hannelore RÖmich ◽  
Helmut Schmidt
Keyword(s):  
Chemical Composition ◽  
Ir Spectroscopy ◽  
Environmental Stress ◽  
Silicate Glass ◽  
New Method ◽  
Stained Glass ◽  
Stress Situation ◽  
Conservation Research ◽  
Combined Impact

AbstractGlass sensors, based on K-Ca-silicate glass chips, with a low durability against corrosive stresses, offer a new method for assessing the complex environmental stress situation of monuments and pieces of art. The easy-tohandle technique is able to detect the combined impact of climatic stresses, pollution and microbiological effects as well as synergetic interactions.The chemical composition of the sensitive glasses enables judgements within few months. This way long-term estimates can be obtained without costly long-term investigations.The corrosion progress is determined by microscopy and IR-spectroscopy of the weathered glass sensor surfaces. The sensors are already operating in the field of stained glass window preservation. They monitor the efficiency of different kinds of external protective glazings and the remaining stresses from the in-door environment of cathedrals.

Gate Oxide Long-Term Reliability of 4H-SiC MOS Devices

2010 ◽  
Vol 645-648 ◽  
pp. 805-808 ◽  
Author(s):  
Liang Chun Yu ◽  
Kin P. Cheung ◽  
Greg Dunne ◽  
Kevin Matocha ◽  
John S. Suehle ◽  
...  
Keyword(s):  
High Field ◽  
Field Data ◽  
Gate Oxide ◽  
Early Prediction ◽  
Accelerated Test ◽  
Mos Capacitors ◽  
Mos Devices ◽  
Test Conditions ◽  
Oxide Reliability

Reliability of the gate oxide on SiC is a pressing concern for deploying SiC MOS-based devices in real systems. While good projected oxide reliability was obtained recently under highly accelerated test conditions, indication that such projection may not be valid at lower operating fields was also reported. In this work, results from long-term TDDB stress (over 7 months) at 6 MV/cm and 300 °C on 4H-SiC MOS capacitors is reported. We confirm that lifetime projection from high-field data continues to be valid and no change in field acceleration factor is observed. The discrepancy between our results and the early prediction of poor reliability is examined.

scholarly journals Aem Analyses of SRL 131 Glass Altered as a Function of SA/V

1991 ◽  
Vol 257 ◽  
Author(s):  
James J. Mazer ◽  
John K. Bates ◽  
Bruce M. Biwer ◽  
C. R. Bradley
Keyword(s):  
Experimental Studies ◽  
Volume Ratio ◽  
Scaling Factor ◽  
Experimental Results ◽  
Geologic Repository ◽  
Short Term ◽  
Natural Systems ◽  
Test Conditions ◽  
Solution Volume

Experimental studies of silicate glass/water reactions at low temperatures have previously identified the glass surface area-to-solution volume ratio (SA/V) as a significant rate determining parameter [1-4]. The value produced when SA/V is multiplied by reaction time, hereafter referred to as SVT, has been proposed as a scaling factor for comparing experimental results collected under different test conditions and for extrapolating short-term results to longer periods of time. Developing an understanding of the effect of SAN is needed for modeling experimental results where SA/V ranges in value or may vary during experiments. It is also useful to understand the effect of SA/V for modeling natural systems where this value almost certainly varies, such as during the hydrothermal diagenesis of natural glasses or projecting the long-term reaction of water and borosilicate nuclear waste glass in a geologic repository.

Pd-Ge-Au Ohmic Contacts to GaAs: Reliability and Failure Analysis.

1990 ◽  
Vol 181 ◽  
Author(s):  
T. E. Kazior ◽  
H. Hieslmair ◽  
R. C. Brooks
Keyword(s):  
Failure Analysis ◽  
Ohmic Contacts ◽  
Temperature Stability ◽  
Conventional Furnace ◽  
Test Conditions ◽  
Contact Stability ◽  
Bias Temperature Stress ◽  
Graphite Susceptor ◽  
Temperature Storage

ABSTRACTWe report on experiments that were performed to evaluate the temperature stability and long term reliability of non-alloyed Pd-Ge-Au ohmic contacts on N-type GaAs. Low resistance contacts (≈1×10−6Ωcm2) were obtained for samples that were sintered in a conventional furnace or flash sintered in a graphite susceptor. Elevated temperature storage (≈4000 hours at 280°C) showed improved contact stability when compared to Ni-AuGe-Ni-Au control samples. Gateless MESFETs subjected to bias temperature stress measurements (Ids ≈300-350mA/mm, 2000–4000 hours at 200°C) showed no significant change in device current. This result is in contrast to devices with Ni-AuGe-Ni-Au ohmic contacts which exhibited a 6–27% decrease in current under the same test conditions. Failure analysis reveals significant electromigration and Au diffusion in the drain fingers of devices with Ni-AuGe-Ni-Au contacts. In contrast, devices with Pd-Ge-Au contacts show no electromigration or Au diffusion in the GaAs.

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