Effect of gamma-irradiation on adsorption properties of Slovak bentonites |
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Authors: | M Galamboš M Daňo O Rosskopfová F Šeršeň J Kufčáková R Adamcová P Rajec |
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Institution: | 1. Department of Nuclear Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská Dolina, 842 15, Bratislava, Slovak Republic 2. Institute of Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská Dolina, 842 15, Bratislava, Slovak Republic 3. Department of Engineering Geology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská Dolina, 842 15, Bratislava, Slovak Republic
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Abstract: | One of the basic prerequisites for the use of bentonite as engineering barrier in deep geological repositories for radioactive
waste and spent nuclear fuel is their stability against ionizing radiation stemming from radionuclides present in radioactive
waste and spent nuclear fuel. The aim of this study was to compare the changes in the adsorption properties of selected Slovak
bentonites in relation to uranium fission products (137Cs and 90Sr), prior to and after irradiation of bentonites with a 60Co γ-source and specifying the changes in the structure of Slovak bentonites induced by γ-radiation. The changes in irradiated
natural forms of Slovak bentonites and the changes in their natrified analogues and fractions with different grain sizes were
studied from five Slovak deposits: Jelšovy potok, Kopernica, Lastovce, Lieskovec and Dolná Ves. The EPR spectra of bentonites
from deposits Jelšovy potok and Lieskovec with absorbed doses of 104 and 105 Gy γ-rays showed no changes in the structure of the studied Slovak bentonites. The changes, which in terms of structure destabilization
can be considered insignificant, occurred only in bentonites with absorbed doses of γ-radiation as much as 1 MGy. The absorbed
dose of 1 MGy γ-radiation did not have an effect on the adsorption of cesium on every studied bentonite. Changes that can
also be regarded as insignificant occurred only during strontium adsorption, especially on Fe–bentonite from deposit Lieskovec
and Ca–Mg–bentonite from deposit Jelšovy potok, when an increase in the adsorption capacity occurred. Attention should be
paid in further research of this topic which would require carrying out experiments on bentonite samples with absorbed doses
higher by several orders of magnitude. |
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