Coprecipitation of Sr, Ni and U with CaCO3: An Experimental Study

1995 ◽  
Vol 412 ◽  
Author(s):  
Torbjörn Carlsson ◽  
Hannu Aalto
Keyword(s):  
Experimental Study ◽  
Trace Elements ◽  
Nuclear Waste ◽  
Room Temperature ◽  
Nuclear Waste Repository ◽  
Experimental Conditions ◽  
Waste Repository ◽  
Solid Phases ◽  
Titration Vessel ◽  
Made In

AbstractAt the Finnish candidate sites for a nuclear waste repository, calcite (CaCO3) is a common fracture mineral that may participate in coprecipitation processes. The objective of this preliminary work was to study the coprecipitation of the trace elements Sr, Ni, and U with CaCO3 under controlled conditions. The experiments were made in a titration vessel at room temperature under pure N2 or a 0.1 % CO 2/N2 mixture. The water phase contained CaCl2 (0.01M) and NaCl (0.05 M) to which trace amounts of Ni2+, Sr2+ and UO22+ were initially added. CaCO3 was precipitated by the addition of Na2CO3 and the use of CaCO3 seed crystals. When about 10−4 mol of precipitate had formed, the solution and solid phases were analysed with ICPMS. The results seem to indicate that Ni coprecipitated with CaCO3 under the experimental conditions, while U did not. In the case of Sr, further data are needed in order to make any conclusions from the experiments.

Coprecipitation of Ni With Calcite: An Experimental Study

1997 ◽  
Vol 506 ◽  
Author(s):  
T. Carlsson ◽  
H. Aalto
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Nuclear Waste ◽  
Liquid Scintillation Counting ◽  
Liquid Scintillation ◽  
Solid Phase ◽  
Scintillation Counting ◽  
Nuclear Waste Repository ◽  
Eds Analysis ◽  
Waste Repository

ABSTRACTAt the Finnish candidate sites for a nuclear waste repository calcite (CaCO3) is a common fracture mineral, that may participate in coprecipitation processes. The objective of this work was to study the coprecipitation of the trace element Ni with CaCO3 under controlled conditions. The experiments were carried out at 30 °C in vessels closed to the atmosphere. Calcite-saturated 0.05 M NaCI solutions containing trace amounts of Ni2+ were contacted with calcite for periods of up to 42 days. The experimental data indicate that Ni coprecipitates with calcite as a result of recrystallization. The amounts of coprecipitated Ni and recrystallized calcite were determined using liquid scintillation counting and the isotopes 63Ni and 45Ca. The results are supported by a complementary SEM/EDS analysis of the solid phase.

Strontium Isotopic Study of Fracture Filling Minerals in the Grande Ronde Basalt, Washington

1983 ◽  
Vol 26 ◽  
Author(s):  
D. G. Brookins ◽  
M. T. Murphy ◽  
H. A. Wollenberg
Keyword(s):  
Trace Elements ◽  
Isotopic Composition ◽  
Nuclear Waste ◽  
Isotopic Analysis ◽  
Nuclear Waste Repository ◽  
Vertical Flow ◽  
Isotopic Study ◽  
Hanford Site ◽  
Chemical Studies ◽  
Waste Repository

An important issue for assessing the feasibility of a nuclear waste repository located in basalt at the Hanford Site, Washington, is whether or not waters can percolate vertically through the rocks at the BWIP site. Flow in well defined horizontal, interbed units is well known, but vertical flow has not been fully investigated. Because vertical fractures are common, it is possible that some waters could penetrate the basalts and move normal to the horizontal flow layers. To investigate this, we have chosen to examine the chemistry and isotopics of minerals found in the fractures. These minerals may have originated earlier in the basalt history, i.e. deuteric, in which case their chemistry and isotopic composition should reflect that of the basalt. Alternately, they may have formed late in the basalt's history, in which case their chemistry may be a reflection of material deposited from percolating waters. Thirdly, they may represent a mixing of the basalt and groundwater reservoirs. We examined this issue by determining the strontium isotopic composition of the various reservoirs, supported by other chemical studies. In this fashion we have carefully investigated the origin of the strontium and other trace elements in the fracture filling minerals. To date, waters from surface or subsurface reservoirs at Hanford have not been provided for isotopic analysis, although we plan to run these as soon as they are available. Our conclusions on the strontium isotopic work are therefore qualitative to semi-quantitative at best, but the results can be directly applied to the source of the strontium in the fracture filling minerals.

Chemical, Physical and Engineering Characterization Of Candidate Backfill Clays and Clay Admixtures for a Nuclear Waste Respository-Part I

1981 ◽  
Vol 6 ◽  
Author(s):  
Sudesh K. Singh
Keyword(s):  
Nuclear Waste ◽  
Morphological Changes ◽  
Deionized Water ◽  
Engineering Properties ◽  
Nuclear Waste Repository ◽  
Exchange Cation ◽  
Mineral Components ◽  
Waste Repository ◽  
Mineralogical Compositions

ABSTRACTFourteen Canadian clays and clay admixtures were subjected to simulated nuclear waste repository environments. The present work is concerned with the montmorillonite-dominant materials only. The montmorillonite-dominant samples showed significant leaching on interaction with deionized water. On heating the samples at 200°C for 500 hours, montmorillomites lost intermicellar water completely and acquired cusp-like to cylindrical morphologies. The loss of water and the morphological changes in montmorillonites significantly altered the engineering characteristics. Permeability, shrinkage limits, compactability and shear strength varied in response to the dominant exchange cation in the structure of montmorillonites and the presence of other mineral components in the materials. The synthetic granite water reacted with montmorillonites and led to changes in chemical and mineralogical compositions, crystalline state and engineering properties.

Modelling of thermal rock mass properties at the potential sites of a Swedish nuclear waste repository

2009 ◽  
Vol 46 (6) ◽  
pp. 1042-1054 ◽  
Author(s):  
Jan Sundberg ◽  
Pär-Erik Back ◽  
Rolf Christiansson ◽  
Harald Hökmark ◽  
Märta Ländell ◽  
...  
Keyword(s):  
Rock Mass ◽  
Nuclear Waste ◽  
Nuclear Waste Repository ◽  
Rock Mass Properties ◽  
Mass Properties ◽  
Waste Repository
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