Recrystallization and Uptake of <sup>226</sup>Ra into Ba-Rich (Ba,Sr)SO<sub>4</sub> Solid Solutions
<sup>226</sup>Ra is an important contributor to naturally occurring radioactive materials (NORM) and also considered in safety cases related to the disposal of spent nuclear fuel in a deep geological repository. Recrystallization and solid solution formation with sulfates is regarded as...
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MDPI AG
2020-09-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/10/9/812 |
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| author | Felix Brandt Martina Klinkenberg Jenna Poonoosamy Dirk Bosbach |
| author_facet | Felix Brandt Martina Klinkenberg Jenna Poonoosamy Dirk Bosbach |
| author_sort | Felix Brandt |
| collection | DOAJ |
| description | <sup>226</sup>Ra is an important contributor to naturally occurring radioactive materials (NORM) and also considered in safety cases related to the disposal of spent nuclear fuel in a deep geological repository. Recrystallization and solid solution formation with sulfates is regarded as an important retention mechanism for <sup>226</sup>Ra. In natural systems sulfates often occur as (Ba,Sr)SO<sub>4</sub>. Therefore, we have chosen this solid solution at the Ba-rich end for investigations of the <sup>226</sup>Ra uptake. The resulting <sup>226</sup>Ra-solubility in aqueous solution was assessed in comparison with a thermodynamic model of the solid solution-aqueous solution system (Ba,Sr,Ra)SO<sub>4</sub> + H<sub>2</sub>O. The temperature and composition of the initial (Ba,Sr)SO<sub>4</sub> solid solution were varied. Measurements of the solution composition were combined with microscopic observations of the solid and thermodynamic modeling. A complex recrystallization behavior of the solid was observed, including the dissolution of significant amounts of the solid and formation of metastable phases. The re-equilibration of Ba-rich (Ba,Sr)SO<sub>4</sub> to (Ba,Sr,Ra)SO<sub>4</sub> leads to a major reconstruction of the solid. Already trace amounts of Sr in the solid solution can have a significant impact on the <sup>226</sup>Ra solubility, depending on the temperature. The experimental findings confirm the thermodynamic model, although not all solids reached equilibrium with respect to all cations. |
| first_indexed | 2024-03-10T16:19:48Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-10T16:19:48Z |
| publishDate | 2020-09-01 |
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| series | Minerals |
| spelling | doaj.art-a59063d31b3c40498cb250a103d88cfa2023-11-20T13:46:30ZengMDPI AGMinerals2075-163X2020-09-0110981210.3390/min10090812Recrystallization and Uptake of <sup>226</sup>Ra into Ba-Rich (Ba,Sr)SO<sub>4</sub> Solid SolutionsFelix Brandt0Martina Klinkenberg1Jenna Poonoosamy2Dirk Bosbach3Institute of Energy and Climate Research (IEK-6)-Nuclear Waste Management and Reactor Safety, Forschungszentrum Jülich GmbH, 52425 Jülich, GermanyInstitute of Energy and Climate Research (IEK-6)-Nuclear Waste Management and Reactor Safety, Forschungszentrum Jülich GmbH, 52425 Jülich, GermanyInstitute of Energy and Climate Research (IEK-6)-Nuclear Waste Management and Reactor Safety, Forschungszentrum Jülich GmbH, 52425 Jülich, GermanyInstitute of Energy and Climate Research (IEK-6)-Nuclear Waste Management and Reactor Safety, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany<sup>226</sup>Ra is an important contributor to naturally occurring radioactive materials (NORM) and also considered in safety cases related to the disposal of spent nuclear fuel in a deep geological repository. Recrystallization and solid solution formation with sulfates is regarded as an important retention mechanism for <sup>226</sup>Ra. In natural systems sulfates often occur as (Ba,Sr)SO<sub>4</sub>. Therefore, we have chosen this solid solution at the Ba-rich end for investigations of the <sup>226</sup>Ra uptake. The resulting <sup>226</sup>Ra-solubility in aqueous solution was assessed in comparison with a thermodynamic model of the solid solution-aqueous solution system (Ba,Sr,Ra)SO<sub>4</sub> + H<sub>2</sub>O. The temperature and composition of the initial (Ba,Sr)SO<sub>4</sub> solid solution were varied. Measurements of the solution composition were combined with microscopic observations of the solid and thermodynamic modeling. A complex recrystallization behavior of the solid was observed, including the dissolution of significant amounts of the solid and formation of metastable phases. The re-equilibration of Ba-rich (Ba,Sr)SO<sub>4</sub> to (Ba,Sr,Ra)SO<sub>4</sub> leads to a major reconstruction of the solid. Already trace amounts of Sr in the solid solution can have a significant impact on the <sup>226</sup>Ra solubility, depending on the temperature. The experimental findings confirm the thermodynamic model, although not all solids reached equilibrium with respect to all cations.https://www.mdpi.com/2075-163X/10/9/812radium uptakerecrystallization(Ba,Sr,Ra)SO<sub>4</sub> solid solutionbaritecelestinenuclear waste management |
| spellingShingle | Felix Brandt Martina Klinkenberg Jenna Poonoosamy Dirk Bosbach Recrystallization and Uptake of <sup>226</sup>Ra into Ba-Rich (Ba,Sr)SO<sub>4</sub> Solid Solutions Minerals radium uptake recrystallization (Ba,Sr,Ra)SO<sub>4</sub> solid solution barite celestine nuclear waste management |
| title | Recrystallization and Uptake of <sup>226</sup>Ra into Ba-Rich (Ba,Sr)SO<sub>4</sub> Solid Solutions |
| title_full | Recrystallization and Uptake of <sup>226</sup>Ra into Ba-Rich (Ba,Sr)SO<sub>4</sub> Solid Solutions |
| title_fullStr | Recrystallization and Uptake of <sup>226</sup>Ra into Ba-Rich (Ba,Sr)SO<sub>4</sub> Solid Solutions |
| title_full_unstemmed | Recrystallization and Uptake of <sup>226</sup>Ra into Ba-Rich (Ba,Sr)SO<sub>4</sub> Solid Solutions |
| title_short | Recrystallization and Uptake of <sup>226</sup>Ra into Ba-Rich (Ba,Sr)SO<sub>4</sub> Solid Solutions |
| title_sort | recrystallization and uptake of sup 226 sup ra into ba rich ba sr so sub 4 sub solid solutions |
| topic | radium uptake recrystallization (Ba,Sr,Ra)SO<sub>4</sub> solid solution barite celestine nuclear waste management |
| url | https://www.mdpi.com/2075-163X/10/9/812 |
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