Glasses for Nuclear Waste Immobilization. Effect of Lutetium Addition on Yttrium Aluminosilicate Glass Crystallization Kinetics

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
D. C. Lago ◽  
M. B. Bortot ◽  
M. O. Prado
Keyword(s):  
Crystallization Kinetics ◽  
Term Treatment ◽  
Silicate Glasses ◽  
Aluminosilicate Glass ◽  
Radioactive Material ◽  
Glass Crystallization ◽  
Long Term Treatment ◽  
Order Of Magnitude ◽  
Yttrium Disilicate ◽  
Nuclear Waste Immobilization

Glasses have emerged as alternative materials that can be used for long-term treatment and management of radioactive waste. Specifically, glasses can be used as a matrix to immobilize the radioactive material. Within the glass industry, silicate glasses are the most widely used due to their properties and to the large knowledge existent about them. Alkaline free silicate glasses are particularly corrosion resistant. Due to the latter, rare earth aluminosilicate glasses are good candidates for actinides immobilization, especially, yttrium aluminosilicate (YAS) glasses. The crystallization kinetics of YAS glasses on heating has been already studied, and this work is focused on the effect of lutetium addition on the YAS glass crystallization kinetics. The presence of a small amount of lutetium in a YAS glass decreases the surface density of nucleation sites (Ns) by about 1 order of magnitude and significantly decreases the crystal growth rate (U). In this work, it was observed that lutetium additions on the order of 0.2 (wt %) to a YAS glass dramatically decreased Ns, for example, at 1000 °C from 1011 to 109 nuclei/m2. Additionally, U for yttrium disilicate phase decreased from (8.21 ± 0.28) μm/h to (0.54 ± 0.04) μm/h at the same temperature.

Changes in Glomerular Filtration Rate during Long-Term Treatment with Propranolol in Patients with Arterial Hypertension

1973 ◽  
Vol 44 (2) ◽  
pp. 129-134 ◽  
Author(s):  
H. Ibsen ◽  
P. Sederberg-Olsen
Keyword(s):  
Blood Flow ◽  
Glomerular Filtration Rate ◽  
Arterial Hypertension ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Term Treatment ◽  
Long Term Treatment ◽  
Order Of Magnitude ◽  
51Cr Edta

1. Glomerular filtration rate was determined from 51Cr—EDTA clearance in twenty hypertensive subjects treated with propranolol. 2. A significant mean decrease of 13% in the glomerular filtration rate was found during treatment, and an increase of the same order of magnitude after withdrawal of propranolol. 3. It is suggested that these changes are related to a reduction in the renal blood flow. 4. No significant changes were found in plasma volume.

Crystallization of an Yttrium Aluminosilicate Glass for Nuclear Waste Immobilization

2012 ◽  
Vol 1475 ◽  
Author(s):  
Diana Carolina Lago ◽  
Diana Garcés ◽  
Miguel Oscar Prado
Keyword(s):  
Particle Size ◽  
Cross Sections ◽  
Glass Particle ◽  
Aluminosilicate Glass ◽  
Glassy Matrix ◽  
Borosilicate Glasses ◽  
Aluminosilicate Glasses ◽  
Waste Immobilization ◽  
Yttrium Disilicate ◽  
Nuclear Waste Immobilization

ABSTRACTSiO2-Al2O3-Y2O3 glasses exhibit high glass transition temperatures, water corrosion resistance and good mechanical properties. These properties suggest that yttrium aluminosilicate glasses could potentially replace the borosilicate glasses usually used for immobilization of nuclear wastes. At the same time, yttrium can be used to simulate actinides.During waste immobilization, crystallization of the glassy matrix must be avoided or at least controlled, thus, the understanding of glass crystallization kinetics is essential.We found by XRD that the crystalline phases present on heat treatments are yttrium disilicate and sillimanite/mullite. By optical microscopy on polished cross-sections we could only identify highly yttrium enriched crystals which we associate with yttrium disilicate crystals.In this paper we measure the surface density of nucleation sites Ns in as obtained splat cooled pieces obtaining values of about 1.5 · 1011 nucleus · m-2. Crystal growth rate U in the temperature range 1000-1040 oC varies in the range 8-13 μm · h-1. These data are useful for designing sintering or melting thermal paths of YAS glasses in order to control their microstructure. We show the effect of glass particle size on DTA results: crystallization peaks moves towards lower temperatures for smaller particle size, which confirms that mainly surface nucleation is taking place on heating.

Ionic Conductivity of Hydrous Silicate Glasses

2006 ◽  
Vol 46 ◽  
pp. 89-92
Author(s):  
Sara Fanara ◽  
Harald Behrens ◽  
Regina Kappes
Keyword(s):  
Ionic Conductivity ◽  
Proton Conductivity ◽  
Water Distribution ◽  
Silicate Glasses ◽  
Aluminosilicate Glass ◽  
Karl Fischer Titration ◽  
Oh Groups ◽  
Infrared Microspectroscopy ◽  
Hydrous Silicate ◽  
Order Of Magnitude

Hydrous silicate glasses with different compositions (LiAlSi4O10, CaMgSi2O6, CaMgSi2O6 - CaAl2Si2O8 and (Ca,Ba,Sr)O – SiO2) containing up to 3 wt% H2O were synthesized in platinum capsules at high temperature and pressures from 100 to 500 MPa in an internally heated gas pressure vessel. The water content of the glasses was analyzed by Karl-Fischer titration. Using infrared microspectroscopy the homogeneity of water distribution in the samples was checked and concentrations of OH- groups and H2O molecules were estimated. Frequency-dependent ionic conductivity of the glasses was investigated using impedance spectroscopy. It is shown that the proton conductivity is usually orders of magnitude lower than the partial conductivity of alkalis in silicate glasses. Proton conductivity in hydrous barium silicate glass was found to be more than one order of magnitude higher than in an aluminosilicate glass, supporting that the concentration of non-bridging oxygen is crucial for proton conduction in glasses.

Hypnotherapy is effective in the long-term treatment of functional dyspepsia

2001 ◽  
Vol 120 (5) ◽  
pp. A115-A115 ◽  
Author(s):  
E CALVERT ◽  
L HOUGHTON ◽  
P COOPER ◽  
P WHORWELL
Keyword(s):  
Functional Dyspepsia ◽  
Term Treatment ◽  
Long Term Treatment

1608: Long-Term Treatment with High Doses of Sildenafil Does Not Up-Regulate the Levels of Phosphodiesterase 5 (Pde5) in the Rat Penis

2004 ◽  
Vol 171 (4S) ◽  
pp. 424-424 ◽  
Author(s):  
Monica G. Ferrini ◽  
Eliane G. Valente ◽  
Jacob Rajfer ◽  
Nestor F. Gonzalez-Cadavid
Keyword(s):  
Term Treatment ◽  
Long Term Treatment ◽  
High Doses ◽  
Phosphodiesterase 5

Long-Term Treatment Outcomes for Heroin Dependence: The 11-Year Follow-Up of the ATOS Study

2013 ◽  
Author(s):  
Christina Marel ◽  
Maree Teesson ◽  
Shane Darke ◽  
Katherine Mills ◽  
Joanne Ross ◽  
...  
Keyword(s):  
Treatment Outcomes ◽  
Term Treatment ◽  
Heroin Dependence ◽  
Long Term Treatment
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