This title appears in the Scientific Report :
2019
The Uptake of 226Ra during the Recrystallization of Barite: Effect of Ionic Strength, Sraq and Temperature
The Uptake of 226Ra during the Recrystallization of Barite: Effect of Ionic Strength, Sraq and Temperature
In recent safety cases for the deep geological disposal of spent nuclear fuel, 226Ra is regarded as a relevant radionuclide. Therefore, retention mechanisms e.g. sorption or uptake in solid solutions are studied, aiming at a more realistic thermodynamic description of the fate of 226Ra under reposit...
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Personal Name(s): | Klinkenberg, Martina (Corresponding author) |
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Brandt, Felix / Poonoosamy, Jenna / Weber, Juliane / Bosbach, Dirk | |
Contributing Institute: |
Nukleare Entsorgung; IEK-6 |
Imprint: |
2019
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Conference: | Goldschmidt 2019, Barcelona (Spain), 2019-08-18 - 2019-08-23 |
Document Type: |
Poster |
Research Program: |
Nuclear Waste Management |
Publikationsportal JuSER |
In recent safety cases for the deep geological disposal of spent nuclear fuel, 226Ra is regarded as a relevant radionuclide. Therefore, retention mechanisms e.g. sorption or uptake in solid solutions are studied, aiming at a more realistic thermodynamic description of the fate of 226Ra under repository relevant conditions. Due to the presence of Ba in spent nuclear fuel which may be released during corrosion and sulfate in many groundwaters, the uptake of 226Ra and the thermodynamics of the(Ra,Ba)SO4 solid are currently studied. Despite the presence of strontium in many groundwaters, so far little is known about the effect of aqueous Sr concentrations (Sraq) on the recrystallization and 226Ra uptake process as well as about the effect of ionic strength. were, we present new experimental data on the recrystallization of barite to unravel the effect of Sraq and ionic strength on the 226Ra uptake kinetics and solubility. Final Ra concentrations (Raaq) are interpreted based on a recent thermodynamic model for the (Ba,Sr,Ra)SO4 solid solution. With higher ionic strength, the final 226Ra concentrations are close to predicted values for low solid/liquid (S/L) ratios whereas at high S/L further kinetically driven Ra-uptake was observed. In contrast to ionic strength, the presence of Sraq can have a significant inhibiting effect on the 226Ra-uptake into barite which depends on temperature and the S/L ratio. In the extreme case of low S/L ratio and ambient temperature conditions, a complete inhibition of Ra-uptake into barite was observed. At higher temperatures the uptake kinetics were affected by the presence of Sr, the final Raaq were close to the predicted thermodynamic equilibrium[1]. [1] Brandt et al.(2018) Minerals 8(11), 520. |