Implications of Analcime Hydrothermally Formed from Na-alumino-borosilicate Glasses Containing Cs and Sr for the Stability of High-level Radioactive Waste Form |
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| Authors: | Wook Sohn Tetsuya Shoji Hiroaki Kaneda Teruaki Ishii |
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| Institution: | Department of Geosystem Engineering, School of Engineering, The University of Tokyo, 7–3-1 Hongo, Bunkyo-ku, Tokyo 113–8656, Japan;Department of Environment Systems, School of Frontier Sciences, The University of Tokyo, 7–3-1 Hongo, Bunkyo-ku, Tokyo 113–0033, Japan;Division of Ocean Floor Geotectonics, Ocean Research Institute, The University of Tokyo, 1–15–1 Minamidai, Nakano-ku, Tokyo 164–8639, Japan |
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| Abstract: | Abstract. In order to know the behaviors of radioactive elements such as cesium and strontium during a hydrothermal alteration of borosilicate glass of radioactive waste, some alumino-borosilicate glasses belonging to the systems Na2O-Al2O3-B2O3-SiO2-SrO, Na2O-Al2O3-B2O3-SiO2-Cs2O and Na2O-Al2-O3-B2O3-SiO2-SrO-Cs2O have been treated hydrothermally at 200 C under a vapor pressure of 1.54 MPa. The result shows that all glasses are changed into crystalline phases with running time up to 60 days, and that analcime-type zeolite is formed as a major product. The formed zeolite is shown to contain cesium and/or strontium. Considering the fact that natural zeolite occurs in wide physicochemical conditions including hydrothermal one, the analcime-type zeolite is expected to fix stably the radioactive elements in the disposal site. Since aluminum is necessary for the formation of the analcime-type zeolite, the waste glass should have aluminum as one of major components. |
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| Keywords: | radioactive waste borosilicate glass alteration analcime-type zeolite cesium strontium |
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