Diffusion Measurements in Concrete and Compacted Bentonite

1982 ◽  
Vol 15 ◽  
Author(s):  
A. Muurinen ◽  
J. Rantanen ◽  
R. Ovaskainen ◽  
O.J. Heinonen
Keyword(s):  
Cylindrical Sample ◽  
Laboratory Method ◽  
Theoretical Curve ◽  
Concentration Profiles ◽  
Sodium Bentonite ◽  
Diffusion Data ◽  
Compacted Bentonite ◽  
Measured Profile

ABSTRACTA laboratory method for measurement of diffusion of radionuclides inconcretes and compacted bentonite has been developed. In this method a tracer is introduced through one end into the cylindrical sample closed in a tube and preequilibrated with water. After the introduction period of the tracer the tube is sealed hermetically and the concentration profiles of the radionuclides are measured periodically from the outside of the sample using a collimated detector. Diffusivities are calculated from the activity profiles by fitting the theoretical curve with the measured profile. The paper will give diffusion data for Co, Sr and Cs in some concrete products and for Co and Cs in compacted sodium bentonite.

Influence of Operational Conditions on Retardation Parameters Measured by Diffusion Experiment in Compacted Bentonite

2010 ◽  
Vol 1265 ◽  
Author(s):  
Ishii Yasuo ◽  
Yoshimi Seida ◽  
Yukio Tachi ◽  
Hideki Yoshikawa
Keyword(s):  
Mass Transfer ◽  
Ionic Strength ◽  
Test Solution ◽  
Test Method ◽  
Diffusion Experiment ◽  
Mass Transfer Resistance ◽  
Transfer Resistance ◽  
Operational Conditions ◽  
Diffusion Data ◽  
Compacted Bentonite

AbstractInfluence of operation factors in diffusion test of compacted bentonite (such as agitation of test solution in the reservoir, feed rate of the test solution and mass transfer resistance in the filter) on the diffusion data was examined by reservoir depletion (RD) test method using Cs+. The influence of these factors on the diffusion data was also analyzed based on the mathematical sorption-diffusion model which considered the feed of test solution and mass transfer resistance in the filter as well. The reservoir depletion data showed some remarkable influences of these operational conditions, especially in the system with low ionic strength. Change in mass transfer resistance at filter-compacted bentonite due to the operational conditions was found to be potential factor which disturb the diffusion data. The influence was reduced in the system with high ionic strength of solution.

Diffusion Mecflanisms of Srrontium and Cesium in Compacrtd Sodium Bentonite

1986 ◽  
Vol 84 ◽  
Author(s):  
Armo Muurinen ◽  
Pirkkd Penitä-Hiltunen ◽  
Juba Rantanen
Keyword(s):  
Stationary State ◽  
Effective Diffusivity ◽  
Radioactive Tracer ◽  
Pore Diffusion ◽  
Batch Experiments ◽  
Diffusion Measurement ◽  
Sodium Bentonite ◽  
Compacted Bentonite ◽  
Effective Diffusivities

AbstractIn this research the diffusion of strontium and cesium through bento- nite slabs in stationary state has been measured. The measurement gives directly the transport through the sample and the corresponding effective diffusivity. The apparent diffusivity, diffusivity of the sorbed ions as well as the sorption factors can also be evaluated on the basis of the same diffusion measurement. The sorption on the coxmpacted bentonite has also been measured in a special sorption test where a radioactive tracer has been allowed to diffuse into compacted bentonite until equilibrium was reached.The measured effective diffusivities were clearly higher than they would be in the case of pure pore diffusion. The effective diffusivities also increase with K and the apparent diffusivities are almost independent on KD. This supports the theory that also the sorbed ions diffuse in their own phase. The sorption factors of the compacted bentonite correspond to the values of the batch experiments.

Swelling Pressures of Compacted Bentonite/Sand Mixtures

1984 ◽  
Vol 44 ◽  
Author(s):  
M. N. Gray ◽  
S. C. H. Cheung ◽  
D. A. Dixon
Keyword(s):  
Threshold Value ◽  
Deionized Water ◽  
Silica Sand ◽  
Dry Density ◽  
Sodium Bentonite ◽  
Compacted Bentonite ◽  
Bentonitic Clay ◽  
Soil Fabric ◽  
Nuclear Fuel Waste ◽  
Limiting Value

AbstractCompacted bentonitic clay/sand mixtures are being considered for use as buffer materials in the Canadian concept for nuclear fuel waste disposal. This paper describes a laboratory study of the swelling pressures that develop in statically compacted, air-dry specimens of mixtures of sodium bentonite and silica sand as they are saturated with double-distilled, deionized water. The results are interpreted with the aid of scanning electron microscope observations of the soils' structures.It is shown that the sand acts as an inert filler material, and swelling pressures are controlled by a parameter termed the effective clay dry density, γC, defined as the ratio of the mass of clay to the combined volume of the claq plus voids in the mixture. A threshold value of γC exists below which swelling pressures can be expected to be isotropic. Above the threshold value of γC, pressures parallel to the axis of compaction can be expected to be greatgr than those perpendicular to it. This is related to a change in soil fabric as γC is increased above the threshold value. For the Canadian disposal concept, γC would probably be below the limiting value and swelling pressures of 2.5 MPS or less are expected. The swelling pressures are likely to be isotropic within a saturated buffer mass.

Seismic anisotropy in sedimentary rocks, part 1: A single‐plug laboratory method

Geophysics ◽  
2002 ◽  
Vol 67 (5) ◽  
pp. 1415-1422 ◽  
Author(s):  
Zhijing Wang
Keyword(s):  
Seismic Anisotropy ◽  
Transverse Isotropy ◽  
Transversely Isotropic ◽  
Cylindrical Sample ◽  
Laboratory Method ◽  
Piezoelectric Transducers ◽  
Low Permeability ◽  
Seismic Velocities ◽  
Fluid Displacement ◽  
Fluid Saturation

A single‐plug method for measuring seismic velocities and transverse isotropy in rocks has been rigorously validated and laboratory tested. The method requires only one sample to measure the velocities needed to derive the five independent elastic constants for transversely isotropic materials. In this method, piezoelectric transducers are fitted to the top, bottom, and sides of the cylindrical sample. Laboratory velocity and anisotropy can be measured as functions of pressure, temperature, fluid saturation, and fluid displacement. Because this method uses a horizontal core plug that has much higher permeability than a vertical core plug, it is especially suitable for low‐permeability shale measurements. It reduces the sample preparation and velocity measurement time by more than two‐thirds.

A SIMPLE METHOD FOR TESTING THE FRACTAL DIMENSION OF COMPACTED BENTONITE IMMERSED IN SALT SOLUTION

2017 ◽  
Vol 24 (03) ◽  
pp. 1750040 ◽  
Author(s):  
GUOSHENG XIANG ◽  
YONGFU XU ◽  
SHENGHUA XIE ◽  
YUAN FANG
Keyword(s):  
Fractal Dimension ◽  
Salt Solution ◽  
Void Ratio ◽  
Nitrogen Adsorption ◽  
Laboratory Method ◽  
Nacl Solution ◽  
Simple Method ◽  
Sodium Chloride Solutions ◽  
Compacted Bentonite ◽  
Deformation Test

This study employs swelling deformation test for estimating the fractal dimension of salt-modified bentonite soil by measuring the void ratio of montmorillonite ([Formula: see text]) and the effective stress ([Formula: see text]). For the compacted Tsukinuno bentonite, a typical Na-montmorillonite, the fractal dimension is tested by the swelling deformation test conducted in sodium chloride solutions with different concentrations. According to the results, the fractal dimension of the specimens is essentially constant irrespective of the concentration of inundating NaCl solution. The strong correlation of the results from the swelling deformation test with those from the nitrogen adsorption test indicates that the swelling deformation test is an effective laboratory method for testing the fractal dimension of compacted bentonite in salt solution.

scholarly journals Numerical Simulation of Alteration of Sodium Bentonite by Diffusion of Ionic Groundwater Components

1987 ◽  
Vol 112 ◽  
Author(s):  
J. S. Jacobsen ◽  
C. L. Carnahan
Keyword(s):  
Numerical Simulation ◽  
Ion Exchange ◽  
Nuclear Waste ◽  
Chemical Properties ◽  
Sodium Bentonite ◽  
Compacted Bentonite ◽  
Transport Code ◽  
Complexation Reactions ◽  
Aqueous Complexation ◽  
Calcium Bentonite

AbstractBecause of its ability to retard the movement of radionuclides, sodium bentonite is being considered as a packing and backfilling material in a number of nuclear waste isolation programs. Few studies, however, have considered how the chemical properties of the bentonite backfill will vary with distance from the canister and change in time as groundwater constituents diffuse through the bentonite. Of particular importance is the conversion of sodium bentonite to calcium bentonite by ion exchange, which will in turn affect the migration of cationic radionuclides, such as Cs+ and Sr2+, leaking from a waste canister.Experiments measuring the movement of trace amounts of radionuclides through compacted bentonite have typically used unaltered bentonite. Models based on experiments such as these may not lead to accurate predictions of the migration through altered or partially altered bentonite of radionuclides that undergo ion exchange. To address this problem, we have modified an existing transport code to include ion exchange and aqueous complexation reactions. The code is thus able to simulate the diffusion of major ionic groundwater components through bentonite and reactions between the bentonite and groundwater. Numerical simulations have been made to investigate the conversion of sodium bentonite to calcium bentonite for a reference groundwater characteristic of deep granitic formations.

Diffusion Measurements in Compacted Bentonite

1981 ◽  
Vol 6 ◽  
Author(s):  
B. Torstenfelt ◽  
K. Andersson ◽  
H. Kipatsi ◽  
B. Allard ◽  
U. Olofsson
Keyword(s):  
Bentonite Clay ◽  
Concentration Profiles ◽  
Diffusion Cell ◽  
Compacted Bentonite ◽  
Order Of Magnitude ◽  
Very High

ABSTRACTThe diffusion of Cs, Sr, Am and Tc in compacted bentonite clay has been studied, using a diffusion cell where diffusion takes place axially from the center of a cylinder of the clay. The effect of addition of potential radionuclide getters to the clay (apatite for Am, pyrite, olivine, and Fe(s) for Tc) as well as using complexed (acetate) or colloidal Am has been studied.The diffusivities obtained for Cs and Sr were very high − 9.0×10−13 m2/s and 2.6×10−12 m2/s, considering that if the effect of sorption on the clay 9is 2 substracted the diffusivities would be 1.8×10−9 m2/s and 3.1×10−8 m2 /s. These diffusivities are, however, maximum values as the concentration profiles do not follow the theoretical form for these nuclides. A small amount of the ions seems to migrate very fast, while the rest moves slower.For Tc, that may be expected I b2 anionic and thus poorly sorbed, a diffusivity of 5.3×10−11 m2/s was obtained. Addition of Fe(s) decreases the diffusivity by one order of magnitude while olivine and pyrite have no measurable influence during the present contact times (2-3 months). Americium is practically immobile.

Productivity of corn hybrids of different fao groups depending on microfertilizers and growth stimulants under irrigation in the south of Ukraine

2016 ◽  
Vol 3 (1) ◽  
pp. 55-60
Author(s):  
Yu. Lavrynenko ◽  
R. Vozhegova ◽  
O. Hozh
Keyword(s):  
Grain Quality ◽  
Laboratory Method ◽  
The South ◽  
Corn Hybrids ◽  
Early Maturity ◽  
Effi Ciency ◽  
Grain Moisture ◽  
Grain Productivity ◽  
The Impact

The purpose of the research is to identify effi cient microfertilizers and growth stimulants considering biologi- cal features of new corn hybrids of different FAO groups under irrigation conditions in the South of Ukraine and trace their impact on grain productivity of the plants. The methods of the research are the fi eld method – to study the interaction of the research object with experimental factors of the natural environment, to register the yield and evaluate the biometrical indices; the laboratory method – to measure soil moisture, grain moisture content and grain quality indices; the statistical method – to evaluate the reliability of the obtained results; the calculation methods – for economic and energetic assessment of the growing techniques used. The results of the research. The paper defi nes the impact of microfertilizers and growth stimulants on the yield and grain quality of the corn hybrids of different maturity groups and on the economic effi ciency of growing them. The conclusions of the research. Under irrigation conditions of the Southern Steppe of Ukraine it is recommended that the following hybrids should be grown in dark-chestnut soils: early maturity DN Pyvykha, medium-early Skadovskyi, medium maturity Kakhovskyi and medium-late Arabat, using the growth stimulants – treating the seeds with Sezam-Nano and fertilizing with Grainactive at the stage of 7–8 leaves.

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