Some Aspects on the Use of Iron Canisters for HLW

1985 ◽  
Vol 50 ◽  
Author(s):  
Ivars Neretnieks
Keyword(s):  
Bentonite Clay ◽  
Potential Effect ◽  
Hydrogen Gas ◽  
Lithostatic Pressure ◽  
Equilibrium Pressure ◽  
Capillary Suction ◽  
Compacted Bentonite ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Rock Overburden

AbstractIron canisters for high level nuclear waste embedded in compacted bentonite in deep geologic repositories will corrode forming hydrogen gas. The equilibrium pressure (when corrosion would stop) has been estimated to be between 500 and 1000 atm. under repository conditions. As this is much higher than the lithostatic pressure (weight of rock overburden) the gas must be allowed to escape before it disrupts the repository. Escape by diffusion alone is not sufficient but recent experiments have demonstrated that the larger pores in the bentonite are blown free of water and let the gas escape before excessive pressures build up.The potential effect of a capillary breaking layer (CBL) has been explored. A fine layer nearest the canister (e.q. quartz sand) would have much lower capillary suction pressures than the bentonite clay and would keep the water out as long as there is sufficient overpressure. As long as the CBL is void of liquid water no radionuclides can escape, even if the canister is penetrated.

Bentonites -

2021 ◽  
Author(s):  
Wen-An Chiou ◽  
Helmut Coutelle ◽  
Andreas Decher ◽  
Michael Dörschug ◽  
Reiner Dohrmann ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Bentonite Clay ◽  
Drilling Mud ◽  
Uptake Capacity ◽  
Water Uptake Capacity ◽  
High Level Nuclear Waste ◽  
And Performance ◽  
Swelling Clay Minerals ◽  
High Level ◽  
And Control

<p><b>Bentonites</b> are rocks mostly consisting of swelling clay minerals. They were first described from the Cretaceous Benton Shale near Rock River, Wyoming, USA. </p> <p> Because of their useful properties (e.g. highly adsorbent, cation exchanging, swelling), bentonites have many uses, in industry (among them as drilling mud, purification agent, binder, adsorbent, paper production), culture (for e.g. pottery) and medicine/cosmetics/cat litter, civil engineering, and in the future even in the disposal of high-level nuclear waste. </p> <p> Particular chemical characteristics of bentonite clay minerals are rather variable but critically determine their suitability for a particular application. </p> <p> The 15 specialist authors discuss bentonite terminology, classification and genesis and use in eight chapters. Individual chapters deal with the methods bentonites are analysed with, their properties and performance in terms of parameters such as cation exchange capactiy, rheology, coagulation concentraion, water uptake capacity, free swelling, and electrical resistivity (amongst others). </p> <p> A chapter is dedicated to the sources of bentonites, the technology employed to produce them, and how quality control is carried out both in the mine and the laboratory. A further chapter is dedicated to methods of processing the mined material, different activation methods, drying, grinding, and purification. </p> <P> Use cases for bentonites are discussed in a chapter of its own. References, a section on norms and standards, and a list of abbreviations complete the text. </p> <p> The volume addresses students, researchers, and professionals in the mineral industry dealing with bentonite and their clay-mineral constituents, quality assessement and control, and persons that use bentonites in their products. </p>

scholarly journals Response of compacted bentonite to hyperalkalinity and thermal history

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rohini C. Kale ◽  
Bhanwariwal Kapil ◽  
K. Ravi
Keyword(s):  
Thermal History ◽  
Dry Density ◽  
Distilled Water ◽  
Cement Concrete ◽  
Compacted Bentonite ◽  
Concrete Layer ◽  
Geological Repository ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Swell Pressure

AbstractThe use of compacted bentonite around the high-level nuclear waste canister (HLW) inside the deep geological repository (DGR) ensures the prevention of entry of active radionuclides in the atmosphere due to its noteworthy large swelling ability. In the eventual repository, the waste canister has a high (100 °C–200 °C) temperature initially, and it reduces over a vast period, which induces a thermal history over the compacted bentonite layer. The cement/concrete layer is constructed as a bulkhead or in the vaults or to support the access of galleries between a buffer and the host rock, and it degrades over the period. The hyperalkaline fluid is created when it percolates through the cement/concrete layer and comes in contact with the compacted bentonite. The contact of hyperalkaline fluid to compacted bentonite induced with thermal history can hamper the swell pressure characteristic of the bentonite. Therefore to determine the combined effect of hyperalkalinity to the thermal history induced compacted bentonite, swell pressure testing has been conducted on two compacted Barmer bentonites (B1 and B2) specimens with an initial dry density of 1.5 Mg/m3, 1.75 Mg/m3, and 2.0 Mg/m3 and saturated with distilled water as well as with hyperalkaline cement water (W/C = 1 und pH = 12.5) and heated to 110 °C and 200 °C. When the specimens were saturated with hyperalkaline cement water, the swell pressure exerted by both bentonites was noticeably reduced compared to specimens saturated with distilled water. Nevertheless, the time taken to full saturation was longer than distilled water for samples saturated with hyperalkaline cement water. Also, the decrease in swell pressure was observed in the samples subjected to thermal history than samples, which were tested without inducing thermal history in both the cases of hyperalkaline cement water and distilled water. The microstructural observations through XRD, FESEM and EDX revealed the clogging of pores due to the presence of non-swelling minerals.

Prediction for swelling characteristics of compacted bentonite

1996 ◽  
Vol 33 (1) ◽  
pp. 11-22 ◽  
Author(s):  
Hideo Komine ◽  
Nobuhide Ogata
Keyword(s):  
Prediction Method ◽  
Swelling Pressure ◽  
Ion Concentration ◽  
Diffuse Double Layer ◽  
Compacted Bentonite ◽  
Laboratory Test Results ◽  
Swelling Characteristics ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Waste Repositories

Compacted bentonites are attracting greater attention as back-filling (buffer) materials for high-level nuclear waste repositories. For this purpose, it is very important to quantitatively evaluate the swelling characteristics of compacted bentonite. New equations for evaluating the relationship between the swelling deformation of compacted bentonite and the distance between two montmorillonite layers are derived. New equations for evaluating the ion concentration of pore water and the specific surface of bentonite, which significantly influence the swelling characteristics of compacted bentonite, are proposed. Furthermore, a prediction method for the swelling characteristics of compacted bentonite is presented by combining the new equations with the well-known theorectical equations of repulsive and attractive forces between two montmorillonite layers. The applicability of this method was investigated by comparing the predicted results with laboratory test results on the swelling deformation and swelling pressure of compacted bentonites. Key words: bentonite, diffuse double-layer theory, van der Waals force, nuclear wastes disposal, swelling deformation, swelling pressure.

Mcc Corrosion Tests at Reference Testing Conditions for A27 Cast steel in Hanford Ground Water

1986 ◽  
Vol 84 ◽  
Author(s):  
M.D. Merz ◽  
F. Gerber ◽  
R. Wang
Keyword(s):  
Pacific Northwest ◽  
Pressure Vessel ◽  
Static Pressure ◽  
Cast Steel ◽  
Statistical Treatment ◽  
Testing Conditions ◽  
Corrosion Tests ◽  
Corrosion Rates ◽  
High Level Nuclear Waste ◽  
High Level

AbstractThe Materials Characterization Center (MCC) at Pacific Northwest Lab- oratory is performing three kinds of corrosion tests for the Basalt Waste Isolation Project (BWIP) to establish the interlaboratory reproducibility and uncertainty of corrosion rates of container materials for high-level nuclear waste. The three types of corrosion tests were selected to address two distinct conditions that are expected in a repository constructed in basalt. An air/steam test is designed to address corrosion during the operational period and static pressure vessel and flowby tests are designed to address corrosion under conditions that bound the condi ring the post-closure period of the repository.The results of tests at reference testing conditions, which were defined to facilitate interlaboratory comparison of data, are presented. Data are reported for the BWIP/MCC-105.5 Air/Steam Test, BWIP/MCC-105.1 Static Pressure Vessel, and BWIP/MC-105.4 Flowby Test. In those cases where data are available from a second laboratory, a statistical analysis of interlaboratory results is reported and expected confidence intervals for mean corrosion rates are given. Other statistical treatment of data include analyses of the effects of vessel-to-vessel variations, test capsule variations for the flowby test, and oven-to-oven variations for air/steam tests.

Conductivity Behavior of Salt Deposits on the Surface of Engineered Barrier Materials for the Potential High-Level Nuclear Waste Repository at Yucca Mountain, Nevada

2004 ◽  
Vol 824 ◽  
Author(s):  
Lietai Yang ◽  
Miriam R. Juckett ◽  
Roberto T. Pabalan
Keyword(s):  
Electrical Conductance ◽  
Yucca Mountain ◽  
Nuclear Waste Repository ◽  
Conductivity Measurements ◽  
Barrier Materials ◽  
Salt Mixtures ◽  
High Level Nuclear Waste ◽  
Waste Repository ◽  
High Level ◽  
Conductivity Behavior

AbstractThe electrical conductance or conductivity of three salt mixtures, Na-K-Cl-NO3, Ca-K-Cl and Ca-Na-Cl, were measured at 25, 50 and 70°C [77, 122, and 158 °F] as a function of relative humidity (RH). Mutual deliquescence and efflorescence RH (MDRH and MERH) values were determined based on the conductivity measurements. It was found that the conductivity of the three salt mixtures started to increase at RH values that are approximately 40 % of their MDRH and increased by 1to 2 orders of magnitude just before reaching the MDRH. At the MDRH, a significant increase in conductivity was observed. The MDRH and MERH for the Ca-K-Cl and Ca-Na-Cl mixtures were found to be approximately 15 % in the temperature range of 50 to 70 °C [122 to 158 °F]. The MDRH and MERH for the Na-K-Cl-NO3system were found to be approximately 54 % at 50 °C [122 °F] and decreased significantly with an increase in temperature.

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