Long-Term Release from High Level Waste Glass - Part IV: The Effect of Leaching Mechanism

1984 ◽  
Vol 44 ◽  
Author(s):  
Eberhard Freude ◽  
Bernd Grambow ◽  
Werner Lutze ◽  
Harald Rabe ◽  
Rodney C. Ewing
Keyword(s):  
Linear Time ◽  
High Surface ◽  
High Level Waste ◽  
Corrosion Mechanism ◽  
Surface Areas ◽  
One Year ◽  
The Stability ◽  
High Level ◽  
Long Term Behavior

During the past ten years extensive data have been determined for the corrosion of nuclear waste forms in short-term laboratory experiments (usually less than one year). The long-term behavior of glass has been inferred by: (1) the acceleration of corrosion rates at high temperatures [1]; (2) the use of high surface areas of the glass to small volumes of solution [1]; and the analysis of natural glasses altered over long periods of geologic time [2, 3]. The most recent efforts have concentrated on understanding the mechanisms of corrosion [1, 4, 5]. The corrosion mechanism may be used to make long-term extrapolations of the “stability” of the waste form. In this paper, we consider a linear time dependence for the corrosion under near saturation conditions and use a rate equation in the QTERM code [6, 7, 8] to model the long-term behavior of the German glass, C-31−3EC [9], JSS A [10, 11] and SRL TDS 131 [1]. The data base for C-31−3EC has been published elsewhere [9, 12, 13, 14], and we include experimental work completed by Rabe for boron and silica, at 200°C.

Analysis of reacted nuclear-waste glass using electron beams

1994 ◽  
Vol 52 ◽  
pp. 656-657
Author(s):  
E. C. Buck ◽  
N. L. Dietz ◽  
J. K. Bates
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Waste Glass ◽  
High Level Waste ◽  
Secondary Phases ◽  
Surface Areas ◽  
Transmission Electron ◽  
High Level ◽  
Long Term Behavior

When waste glass reacts with water, secondary phases may form, which will effect the distribution of radionuclides formally contained within the glass. In order to determine the long term behavior of waste glass, the secondary phases formed need to be identified. Analytical electron microscopy (AEM) is being used to characterize the secondary phases. Glasses have been reacted in test vessels at different surface areas to leachate volumes (S/V) and for periods in excess of 700 days. Increasing the S/V permits one to accelerate the reaction. Samples of the reacted waste forms are embedded in epoxy and thin sectioned by ultramicrotomy for observation in the transmission electron microscopy (TEM). Examinations were performed in a JEOL 2000FXII TEM operated at 200 kV. This abstract describes two types of glass tests, a high level waste sludge based glass and a low level waste glassy slag. Many hundreds of glass tests have been performed and examined by TEM to determine layer thickness, morphology of the leach layer, and identification of secondary phases.

The Long-Term Corrosion and Modelling of Two Simulated Belgian Reference High-Level Waste Glasses - Part II

1989 ◽  
Vol 176 ◽  
Author(s):  
J. Patyn ◽  
P. Van Iseghem ◽  
W. Timmermans
Keyword(s):  
Pure Water ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
High Level Waste ◽  
Final State ◽  
Leach Rate ◽  
Enhanced Dissolution ◽  
High Level

ABSTRACTThe long term corrosion of two reference Belgian high-level waste glasses (SAN60 and SM58) were investigated in pure water. The corrosion was studied using powdered glass at a high surface area to volume ratio and temperatures of 90 and 120°C. The experimental data at 90°C reveal a “final” leach rate which decreases with time. At 120°C this “final” state is transient and followed by an enhanced dissolution, which was correlated with extensive surface crystallization. Modelling using the PHREEQE and GLASSOL computer codes described the initial corrosion, but was unable to account for the enhanced dissolution at 120°C.

scholarly journals An Assessment of Mesoporous Silica Nanoparticle Architectures as Antigen Carriers

Pharmaceutics ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 294 ◽  
Author(s):  
Xinyue Huang ◽  
Helen E Townley
Keyword(s):  
Mesoporous Silica ◽  
Mesoporous Silica Nanoparticles ◽  
High Surface ◽  
Silica Nanoparticle ◽  
Storage Conditions ◽  
Surface Areas ◽  
Antigen Complex ◽  
The Stability ◽  
And Storage ◽  
Storage Temperatures

Mesoporous silica nanoparticles (MSNPs) have the potential to be used as antigen carriers due to their high surface areas and highly ordered pore network. We investigated the adsorption and desorption of diphtheria toxoid as a proof-of-concept. Two series of nanoparticles were prepared—(i) small pores (SP) (<10 nm) and (ii) large pores (LP) (>10 nm). SBA-15 was included as a comparison since this is commercially available and has been used in a large number of studies. External diameters of the particles ranged from 138 to 1509 nm, surface area from 632 to 1110 m2/g and pore size from 2.59 to 16.48 nm. Antigen loading was assessed at a number of different ratios of silica-to-antigen and at 4 °C, 20 °C and 37 °C. Our data showed that protein adsorption by the SP series was in general consistently lower than that shown by the large pore series. Unloading was then examined at 4 °C, 20 °C and 37 °C and a pH 1.2, 4.5, 6.8 and 7.4. There was a trend amongst the LP particles towards the smallest pores showing the lowest release of antigen. The stability of the MSNP: antigen complex was tested at two different storage temperatures, and storage in solution or after lyophilization. After 6 months there was negligible release from any of the particles under any of the storage conditions. The particles were also shown not to cause hemolysis.

scholarly journals The Disposal of Radioactive Waste in Ice Sheets

1977 ◽  
Vol 19 (81) ◽  
pp. 607-617 ◽  
Author(s):  
K. Philberth
Keyword(s):  
Radioactive Waste ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Climatic Changes ◽  
High Level Waste ◽  
Depth Range ◽  
The Stability ◽  
High Level ◽  
The Antarctic ◽  
Green Land

AbstractThe waste containers should be retrievable for a few centuries until further research has solved all problems and 90Sr and 137Cs have decayed to less than 0.1%. Safe and fairly cheap retrievability can be guaranteed without container mooring. The paper presents an example: The high-level waste of the whole world for the next 30 years could be put in to 3 × 107 spherical containers with 0.2 m radius and disposed of in an area with 15 km radius and a depth range of 20–100 m under the surface of either the Antarctic or the Green land ice sheet. The deposit does not affect the stability of the sheet. Even the most upsetting natural ice-sheet instabilities and/or climatic changes could not cause radioactive contamination.

Long-term changes in rumen fermentation in defaunated sheep

1991 ◽  
Vol 1991 ◽  
pp. 77-77
Author(s):  
P.P. Frumholtz ◽  
R.J. Wallace ◽  
C.J. Newbold ◽  
E.R. Ørskov
Keyword(s):  
Animal Species ◽  
Fish Meal ◽  
Jugular Vein ◽  
Rumen Fermentation ◽  
Bacteria And Fungi ◽  
One Year ◽  
The Stability ◽  
Ciliate Protozoa

The removal of ciliate protozoa, or defaunation, results in the establishment of a new ecosystem in the rumen, consisting only of bacteria and fungi. Although extensive research has been done on ciliate-free ruminants, the role of protozoa in the rumen still provokes considerable debate. The diversity of experimental design, such as animal species, defaunation method, and diet could account for many of the differences observed between defaunation studies. Also it is important to examine the stability of the ciliate-free ecosystem. The aim of this study was to investigate changes in rumen fermentation of ciliate-free sheep over a period of one year.Eight male castrated sheep, weighing 60-70 kg, received twice daily 700 g of a diet of hay, barley, molasses, fish meal and vitamins/minerals (500, 299.5, 100, 91 and 9.5 g/kg DM respectively). Four sheep were defaunated by the rumen washing technique (Jouany and Senaud, 1979) and kept in isolated pens while the other four were left faunated with a mixed type A ciliate protozoa population. Rumen samples were withdrawn via the rumen cannula and blood samples were taken from the jugular vein -1, 0, 1, 2, 4 and 6 h after feeding. There were three sampling periods: one month, six months and one year after defaunation.

scholarly journals Effect of Fe2O3 on the Immobilization of High-Level Waste with Magnesium Potassium Phosphate Ceramic

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Hailin Yang ◽  
Mingjiao Fu ◽  
Bobo Wu ◽  
Ying Zhang ◽  
Ruhua Ma ◽  
...  
Keyword(s):  
Sintering Temperature ◽  
Potassium Phosphate ◽  
High Level Waste ◽  
Radioactive Nuclide ◽  
Hydration Reaction ◽  
Sintering Process ◽  
Positive Role ◽  
Ceramic Structure ◽  
High Level

For the proposed novel procedure of immobilizing HLW with magnesium potassium phosphate cement (MKPC), Fe2O3 was added as a modifying agent to verify its effect on the solidification form and the immobilization of the radioactive nuclide. The results show that Fe2O3 is inert during the hydration reaction. It slows down the hydration reaction and lowers the heat release rate of the MKPC system, leading to a 3°C-5°C drop in the mixture temperature during hydration. Early comprehensive strength of Fe2O3 containing samples decreased slightly while the long-term strength remained unchanged. For the sintering process, Fe2O3 played a positive role, lowering the melting point and aiding the formation of ceramic structure. CsFe(PO4)2, or CsFePO4, was generated by sintering at 900°C. These products together with the ceramic structure and absorption benefit the immobilization of Cs+. The optimal sintering temperature for heat treatment is 900°C; it makes the solidification form a fired ceramic-like structure.

Flow Barrier System for Long-Term High-Level-Waste Isolation: Experimental Results

1998 ◽  
Vol 124 (1) ◽  
pp. 88-100 ◽  
Author(s):  
James L. Conca ◽  
Michael J. Apted ◽  
Wei Zhou ◽  
Randolph C. Arthur ◽  
John H. Kessler
Keyword(s):  
Experimental Results ◽  
High Level Waste ◽  
High Level
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