Use of thermodynamic adsorption models to describe geochemical processes under deep geological repository environments
Deep geological repositories are the most widely accepted international solution to dispose of high activity radioactive wastes. This solution requires an exhaustive analysis of the different containment barriers that will have to isolate these radionuclides for thousands of years so that they are n...
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| Tipo de recurso: | tesis de maestría |
| Fecha de publicación: | 2022 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/369903 |
| Acceso en línea: | https://hdl.handle.net/2117/369903 |
| Access Level: | acceso abierto |
| Palabra clave: | Radioactive waste disposal in the ground Residus radioactius--Eliminació dins el sòl Àrees temàtiques de la UPC::Enginyeria química |
| Sumario: | Deep geological repositories are the most widely accepted international solution to dispose of high activity radioactive wastes. This solution requires an exhaustive analysis of the different containment barriers that will have to isolate these radionuclides for thousands of years so that they are not released into the biosphere prematurely. The last barrier is the geological environment and one of the most important properties that this barrier has is its capacity to retain radionuclides through sorption processes. On the other hand, transuranic elements such as americium or curium are one of the radionuclides with the longest life and radiotoxicity. However, studying these elements is neither easy nor cheap, so the sorption of these elements is usually studied using other more common ones that serve as an analog, europium being the most used. The models used today to describe radionuclide sorption are usually complex, which makes them very sensitive and specific to the conditions used in the experiments, as well as, in some cases, requiring large computational capabilities. Throughout this work we have tried to see how far the sorption models can be simplified. To this aim, we have developed PHREQC-based sorption models capable of explaining europium sorption in illite mineral matrices. As a result, three models have been obtained. Two of which allow simulating some experimental cases without the presence of carbonates within pH ranges between 4 and 10, as well as in concentrations less than 10-6M of europium dissolved in the medium. The last model makes possible to reproduce the sorption of europium in the presence of carbonates within a pH range between 6 and 10, as well as in concentrations less than 10-6M of europium dissolved in the medium. |
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