Thermodynamic Sorption Modelling in Support of Radioactive Waste Disposal Safety Cases : NEA Sorption Project Phase III /
Organisation for Economic Co-operation and Development and Nuclear Energy Agency
Bok Engelsk 2012 Organisation for Economic Co-operation and Development.,· Electronic books.
| Utgitt | Paris : : OECD Publishing, , 2012.
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| Omfang | 1 online resource (155 p.)
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| Opplysninger | Description based upon print version of record.. - Table of contents; List of figures; List of tables; Overview and purpose; 1. Thermodynamic sorption models and radionuclide migration; 1.1. Sorption and radionuclide migration; 1.1. Sensitivity of Kd for U(VI) sorption on geochemical conditions; 1.2. Applications of TSMs in radioactive waste disposal studies; 1.2. Generic radioactive waste disposal concept; 1.3. Requirements for a scientifically defensible, calibrated TSM applicable to radioactive waste disposal; 1.4. Current status of TSMs in radioactive waste management; 2. Theoretical basis of TSMs and options in model development. - 2.1. Conceptual building blocks of TSMs and integration with aqueous chemistry2.2. The TSM representation of sorption and relationship with Kd values; 2.3. Theoretical basis of TSMs; 2.1. Inner sphere and outer sphere surface complexes on a metal oxidesurface are distinguished by the types of chemical bonding between the aqueousion and the surface site; 2.2: Illustration of the co-ordination of hydroxyl groups on a particular (110)surface of goethite; 2.3: Schematic representation of a 2:1 clay mineral platelet with surface sites indicated; 2.4. Example of TSM for uranyl sorption. - 2.1: Summary of surface reactions of uranium sorption on ferrihydrite2.5. Options in TSM development; 2.4: Model of U(VI) sorption on ferrihydrite, showing the computation of both(a) percentage sorbed and (b) Kd using a TSM approach; 2.5: Schematic representation of sources of uncertainty; 2.6. Illustration of TSM development and effects of modelling choices; 2.6: Generalised decision tree for TSM modelling choices; 2.2: Summary of model choices applied to Np(V) sorption onto hematite; 2.7: Results from five different TSM fitting strategies. - 2.7. Summary: TSMs for constraining Kd values - impact of modelling choices3. Determination of parameters for TSMs; 3.1. Overview of experimental determination of TSM parameters; 3.1: Number of additional EDL parameters required to describe surfaceproperties in contact with a 1:1 electrolyte; 3.1: Sorption edge data for Zn measured on Na-montmorilloniteat 0.1 M NaClO4; 3.2: A typical range of system properties considered in the numerical optimisation process; 3.2. Theoretical estimation methods of selected model parameters; 3.2: LFERs for cation adsorption on clays. - 3.3. Case study: sorption modelling of trivalent lanthanides/ actinides on illite3.3: Titration data for Na-illite carried out in 0.01 M, 0.1 M and 0.5 M NaClO4; 3.4: Eu(III)/Am(III) sorption edges on Na-illite measured in 0.1 M NaClO4; 3.5: Sorption isotherm of Eu(III) (labelled with 241Am) on Na-illitein 0.1 M NaClO4 at pH 6.1; 3.4. Indicative values for certain TSM parameters; 3.5. Parameter uncertainty; 3.3: Indicative values for some TSM parameters of important minerals ormineral groups (marked by *), uncertainties represent 2σ (95% confidence level). - 3.6: SSA histogram for amorphous mineral coatings (upper), clay minerals(central) and for crystalline oxides (lower). - A central safety function of radioactive waste disposal repositories is the prevention or sufficient retardation of radionuclide migration to the biosphere. Performance assessment exercises in various countries, and for a range of disposal scenarios, have demonstrated that one of the most important processes providing this safety function is the sorption of radionuclides along potential migration paths beyond the engineered barriers. Thermodynamic sorption models (TSMs) are key for improving confidence in assumptions made about such radionuclide sorption when preparing a repository's safety case. This report presents guidelines for TSM development as well as their application in repository performance assessments. They will be of particular interest to the sorption modelling community and radionuclide migration modellers in developing safety cases for radioactive waste disposal.
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| ISBN | 92-64-17782-5
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