1986 Fiscal Year Final Research Report Summary
Mineralogical Study of Devitrification of Silicate Glasses
| Project/Area Number |
60850115
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
資源開発工学
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| Research Institution | Faculty of Engineering, University of Tokyo |
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Principal Investigator |
TAKENOUCHI Sukune Faculty of Engineering,University of Tokyo, Professor, 工学部, 教授 (30010739)
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| Co-Investigator(Kenkyū-buntansha) |
KANEDA Hiroaki Faculty of Engineering, University of Tokyo, Assistant, 工学部, 助手 (90010892)
SHOJI Tetsuya Faculty of Engineering, University of Tokyo, Associate Professor, 工学部, 助教授 (40011093)
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| Project Period (FY) |
1985 – 1986
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| Keywords | Devitrification / borosilicate glass / high level radioactive wastes / 地層処分 / ガラス固化体 |
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| Research Abstract |
In connection with the terrestrial disposal of high level radioactive wastes, the devitrification of borosilicates was studied under the hydrothermal condition of 200゜C and 15.3 bars, in order to obtain basic data for the evaluation of stability of glass materials. The <SiO_2> - <B_2> <O_3> - <Al_2> <O_3> - <Na_2> O glasses which contained Cs, Sr or Cs+Sr, were heated with water and the beginning of devitrification and the behavior of Cs and Sr at the decomposition of glasses were investigated. The effect of <K_2> O, CaO and <Fe_2> <O_3> to the devitrification was also studied. The crystallization of glasses in the first stage of devitrification was identified on the glass surface as aggregates of micro-crystallites, but the beginning of crystallization differs depending on the composition of glasses. The products of devitrification consist mainly of the crystals of analcite group and various borates. Cs is mainly included in pollucite(analcite group) but Sr is partly trapped in analcite but mostly in borates. Searlesite, quartz and mordenite as an intermediate product were identified. Addition of <Fe_2> <O_3> increased the stability of glasses but <K_2> O decreased it remarkably. The effect of CaO was inbetween that of <Fe_2> <O_3> and <K_2> O. Heating for a half of year at dry condition did not yield any change in glasses. It is concluded that the leached Cs and Sr from devitrified glasses will be trapped in analcites and borates and kept in the system if the amount of invaded water is not too much compared to the glass.
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