Diffusion of Colloids and Other Waste Species in Brine–Saturated Backfill Materials

1983 ◽  
Vol 26 ◽  
Author(s):  
E. J. Nowak
Keyword(s):  
Colloidal Gold ◽  
Diffusion Theory ◽  
Distribution Coefficients ◽  
Low Density ◽  
Sorption Data ◽  
Simple Diffusion ◽  
Diffusion Cells ◽  
Backfill Materials ◽  
Cylindrical Diffusion ◽  
Waste Repositories

ABSTRACTThe diffusion of plutonium (IV) and pertechnetate and the migration of colloidal gold in brine-saturated bentonite was measured. High ionic strength brine characterizes potentially intruding groundwater for radioactive waste repositories in salt. Plastic diffusion cells containing cylindrical diffusion columns were used for low density bentonite. Metal diffusion cells constructed entirely from Hastelloy C-276 were used for the diffusion of pertechnetate in highly compacted bentonite. Apparent distribution coefficients calculated from plutonium diffusion in two columns of low density bentonite are 2 m3/kg and 3 m3/kg. These values are in good agreement with the value of 3m3/kg that was calculated from previous batch sorption data. Pertechnetate anions migrated out of a brine-saturated high density bentonite diffusion column at rates that are too large to be rationalized with a simple diffusion theory. Additional measurements that take into account possible channeling of pertechnetate are required. Colloidal gold was excluded from low density brine-saturated bentonite, but colloidal gold may have channeled between the bentonite and the wall of the diffusion cell. These results support the effectiveness of brine-saturated bentonite as an engineered barrier to plutonium. The results also highlight the need for additional measurements of pertechnetate and gold transport in bentonite. Needs for transport measurements that take into account site-specific materials interactions are also described.

Diffusion of Radionuclides in Brine-Saturated Backfill Barrier Materials

1982 ◽  
Vol 15 ◽  
Author(s):  
E. J. Nowak
Keyword(s):  
Sodium Titanate ◽  
Distribution Coefficients ◽  
Barrier Materials ◽  
Compacted Bentonite ◽  
Metal Diffusion ◽  
Diffusion Cells ◽  
Linear Sorption ◽  
Backfill Materials ◽  
Cylindrical Diffusion ◽  
Apparent Distribution

ABSTRACTThe diffusion of cesium(I), strontium(II), pertechnetate and europium in brine-saturated backfill materials was measured. Plastic diffusion cells containing cylindrical diffusion columns were used for low density backfill materials. The diffusion of gamma-emitters was followed by a gamma scanning technique. Metal diffusion cells constructed entirely from Hastelloy C-276 were used for the diffusion of pertechnetate in highly compacted bentonite. Apparent distribution coefficients calculated from diffusion data are (a) 0.02 m3 /kg for cesium(I) in 40 wt.% mordenite and 60 wt.% bentonite; (b) 0.04 m3/kg for strontium(II) in 10 wt.% sodium titanate and 90 wt.% bentonite; (c) 0.5 m3/kg for pertechnetate in 70 wt.% charcoal and 30 wt.% bentonite; and (d) 3 m3/kg for europium in 100% bentonite. Backfill effectiveness estimates based on batch sorption measurements were supported by these results;however, the diffusion results for europium did not agree well with a model for diffusion retarded by linear sorption. First measurements of pertechnetate diffusion in highly compacted bentonite suggest that anion exclusion may play a role in reducing mass transport rates of anions in this material. Needs for diffusion measurements that take into account site-specific materials interactions are described.

Intralysosomal Accumulation of Colloidal Gold-Low Density Lipoprotein Conjugates in Chloroquine-Treated Fibroblasts

1985 ◽  
Vol 43 ◽  
pp. 546-547 ◽  
Author(s):  
Dean A. Handley ◽  
Cynthia M. Arbeeny ◽  
Larry D. Witte
Keyword(s):  
Colloidal Gold ◽  
Cultured Cells ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Coated Vesicle ◽  
Low Density ◽  
Cholesterol Esters ◽  
Cultured Fibroblasts ◽  
Surface Receptors ◽  
Ldl Particles

Low density lipoproteins (LDL) are the major cholesterol carrying particles in the blood. Using cultured cells, it has been shown that LDL particles interact with specific surface receptors and are internalized via a coated pit-coated vesicle pathway for lysosomal catabolism. This (Pathway has been visualized using LDL labeled to ferritin or colloidal gold. It is now recognized that certain lysomotropic agents, such as chloroquine, inhibit lysosomal enzymes that degrade protein and cholesterol esters. By interrupting cholesterol ester hydrolysis, chloroquine treatment results in lysosomal accumulation of cholesterol esters from internalized LDL. Using LDL conjugated to colloidal gold, we have examined the ultrastructural effects of chloroquine on lipoprotein uptake by normal cultured fibroblasts.

Optical Limiting with Lithium Niobate

1999 ◽  
Vol 597 ◽  
Author(s):  
Gary Cook ◽  
David C. Jones ◽  
Craig J. Finnan ◽  
Lesley L. Taylor ◽  
Tony W. Vere ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Diffusion Theory ◽  
Photovoltaic Effect ◽  
Optical Gain ◽  
Optical Limiting ◽  
Dark Conductivity ◽  
Simple Diffusion ◽  
Beam Coupling ◽  
Coupling Equations ◽  
Focusing Lens

AbstractIron doped lithium niobate (Fe:LiNbO3) in a simple focal plane geometry has demonstrated efficient optical limiting through two-beam coupling. The performance is largely independent of the total Fe concentration and the oxidation state of the Fe ions, providing the linear optical transmission of uncoated crystals is between 30% and 60%. Fe has been found to be the best dopant for LiNbO3, giving the widest spectral coverage and the greatest optical limiting. Optical limiting in Fe:LiNbO3 has been shown to be very much greater than predicted by simple diffusion theory. The reason for this is a higher optical gain than expected. It is suggested that this may be due to an enhancement of the space-charge field arising from the photovoltaic effect. The standard two-beam coupling equations have been modified to include the effects of the dark conductivity. This has produced a theoretical intensity dependence on the ΔOD which closely follows the behaviour observed in the laboratory. A further modification to the theory has also shown that the focusing lens f-number greatly affects the optical limiting characteristics of Fe:LiNbO3. A lens f-number of approximately 20 gives the best results.

Study on Grout Permeation Model of an Equipment for Grouting in Roller Compacted Concrete

2011 ◽  
Vol 287-290 ◽  
pp. 2840-2843 ◽  
Author(s):  
Wei Ping Peng ◽  
Xiong Zhao ◽  
Zhao Liu
Keyword(s):  
Permeability Coefficient ◽  
Diffusion Theory ◽  
Power Station ◽  
Construction Time ◽  
Hydraulic Power ◽  
Roller Compacted Concrete ◽  
Rcc Dam ◽  
Grouting Pressure ◽  
Cylindrical Diffusion ◽  
The Relationship

Based on cylindrical diffusion theory and characteristics of enriched vibrated Roller Compacted Concrete (RCC), a model of grout permeation was established. According to this model and generalized Darcy’s law, a formula was deduced, which shows the relationship among diffusion radius of grout, grouting pressure, radius of grouting pipe, construction time, viscosity of grout, permeability coefficient of RCC, porosity of RCC and rheological index of grout, computing steps by this formula were presented, and results of computing grout diffusion radius for an equipment of grouting in Roller Compacted Concrete was given, which was developed for construction of RCC dam at Tingzikou hydraulic power station.

Experimental investigation on buffer/backfill materials for radioactive waste repository downward facing sorption additivity of cesium, strontium and cobalt with different concentrations

Kerntechnik ◽  
2021 ◽  
Vol 86 (5) ◽  
pp. 375-381
Author(s):  
C.-P. Lee ◽  
Y. Hu ◽  
Y. Sun ◽  
Y. Shi ◽  
N.-C. Tien ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Distribution Coefficients ◽  
Test Method ◽  
Radioactive Waste Disposal ◽  
Batch Test ◽  
Backfill Materials ◽  
Mixing Proportion ◽  
Synthetic Groundwater ◽  
Waste Repository ◽  
Sorption Characteristics

Abstract Buffer/backfill materials for radioactive waste disposal sites consist of pure bentonite or bentonite-rock mixtures. In this study, the batch test method was used to obtain the sorption characteristics of important radionuclides such as Cs, Sr and Co on buffer/backfill materials; i. e., mixing Wyoming MX-80 bentonite or local Taiwanese Zhi-Shin bentonite with possible host rock (argillite and granite) in different proportions (0∼100%). The distribution coefficients (Kd) for Cs, Sr and Co were obtained from the experiments. The distribution coefficient for the bentonite-rock mixtures were found, with more than 50% of mixing proportion of bentonite to argillite or granite, to have very similar values to that of pure bentonite. Furthermore, it was clearly found that the sorption of Cs, Sr and Co to bentonite-rock mixtures is decreased as ionic strength of the liquid phase is increased from 0.001M to 1M for NaCl solutions. According to the experimental results, in synthetic groundwater, it is quite convenient and helpful to assess the distribution coefficients (Kd) of Cs, Sr and Co for buffer/backfill materials using batch sorption experiments with bentonite-rock mixtures of fixed mixing proportions.

Sign in / Sign up

Export Citation Format

Share Document