| Project/Area Number |
03808027
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Nuclear engineering
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
ASANO Mitsuru Kyoto University, Institute of Atomic Energy, Professor, 原子エネルギー研究所, 教授 (80027127)
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| Co-Investigator(Kenkyū-buntansha) |
MIZUTANI Yasuo Kyoto University, Institute of Atomic Energy, Instructor, 原子エネルギー研究所, 助手 (70027134)
HARADA Toshio Kyoto University, Institute of Atomic Energy, Instructor, 原子エネルギー研究所, 助手 (50027132)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1992: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1991: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Fusion reactor / Tritium breeding material / High temperature / Reducing atmosphere / Vaporization / Mass spectrometry / Thermodynamics / Graphite / 還元雰囲気 / 生成エンタルピ- |
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| Research Abstract |
Tritium release behavior from solid breeding materials in fusion reactors is very influenced by the composition of a sweep gas. Lower oxygen potential is essential for larger desorption rate and leads to good compatibility between the breeding materials and stainless steel claddings. For this reason, gas species including oxygen and their partial pressures in equilibrium with many breeding candidate materials existing with graphite were studied by a mass-spectrometric Knudsen effusion method. In addition, the chemical stability of the breeding materials was studied thermodynamically in the reducing atmosphere with the coexistence of graphite. The results are summarized as follows.
1. Enthalpies of formation for Li_2ZrO_3, Li_6Zr_2O_7 and Li_8ZrO_6 in the Li_2O-ZrO_2 system were determined from the data of partial pressures over them. Generally, complex oxides with less Li_2O content are more stable in the Li_2O-MO_X(M=Al, Fe, Mo, Si, Sn, Ti and Zr).
2. The enthalpy of formation for Li_2SnO_3 from constituent oxides is greater than that for Li_2SiO_3; it seems that the value increases in keeping with the atomic number in the IVB group. On the contrary, in the IVA group the enthalpy of formation for Li_2ZrO_3 is smaller than that for Li_2TiO_3.
3. Computer simulation shows that under the reducing condition the ratio of T_2O/T_2 released from the breeding materials becomes small, leading to the large desorption rate. Furthermore, reactions between the breeding materials and the claddings are suppressued markedly.
4. The oxygen partial pressure in the Li_2ZrO_3-graphite system is eight orders of magnitude lower than that in the Li_2ZrO_3-platinum system; that is, the presence of graphite is very useful for the reduction of the oxygen partial pressure.
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