| Project/Area Number |
18540307
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics I
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| Research Institution | Tohoku University |
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Principal Investigator |
INOUE Koji Tohoku University, Tohoku University, Institute for Materials Research, Research Associate (50344718)
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| Co-Investigator(Kenkyū-buntansha) |
NAGAI Yasuyoshi Tohoku University, Institute for Materials Research, Associate Professor (10302209)
HATAKEYAMA Masahiko Tohoku University, Institute for Materials Research, Research Associate (30375109)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,670,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥270,000)
Fiscal Year 2007: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2006: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | positronium / glass / Nanovoids / first-principles calculation |
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| Research Abstract |
High-level radioactive nuclear waste is are immobilised by mixing it with glass to be stored safely for a long time more than 1000 years. These radioactive nuclides are confined in the intrinsic structural nanovoids of the radioactive waste glasses (RWG), usually SiO_2-B2O_3 based glasses. Thus it is very important to study haw the nanovoids are occupied by the radioactive nuclide atoms (ions) and stable under the irradiation environment during the long-term storage.
Many kinds of SiO_2 based model glasses were prepared. We employed two independent experimental methods of positronium (Ps) formed in the nanovoids to obtain average radius of the nanovoids, the average radii are obtained from pick off annihilation hSetime of Ps using Tao-Eldrup-Nakanishi-Wang-Jean model and from two-dimensional angular correlation of positron annihilation (2D-ACAR) momentum distribution using a zero-point bubbles model.
In SiO_2 based model glasses, the average radii from the two experiments agree well with each other except fix slightly smaller radii from the pick-off lifetimes in the glasses containing Fe impurities. The average radius of the nanovoids decreases rapidly with increasing the mole fraction of the doped oxides which belong to the network modifiers (Li, Na and K)because the cation of the oxides occupy nanovoids in the order of the size of them The radius show sluggish and linear change with the fraction. Of the network loaner oxides (B_2O_3, Al_2O_3), which exhibits that the network firmer oxides are incorporated at the glass structural. Networks but not within nanovoids. These findings give us useful into oration on the structural nanovoids and suggest a promising tool for the study of the stability of the RWG during the long-term storage.
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