1998 Fiscal Year Final Research Report Summary
TRITIUM TRAPPING IN MULTI-LAYER PLASMA FACING MATERIALS
| Project/Area Number |
09680489
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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 |
Nuclear fusion studies
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| Research Institution | TOYAMA UNIVERSITY |
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Principal Investigator |
SHU Wei Min Toyama Univ., Hydrogen Isotope Research.Center, A.P.(1997), 水素同位体機能研究センター, 助教授 (70192953)
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| Co-Investigator(Kenkyū-buntansha) |
HATANO Yuji Toyama Univ., Hydrogen Isotope Research.Center, A.P.(1998), 水素同位体機能研究センター, 助教授 (80218487)
MATSUYAMA Masao Toyama Univ., Hydrogen Isotope Research.Center, P., 水素同位体機能研究センター, 教授 (90135004)
WATANABE Kuniaki Toyama Univ., Hydrogen Isotope Research.Center, P., 水素同位体機能研究センター, 教授 (50001326)
ASHIDA Kan Toyama Univ., Hydrogen Isotope Research.Center, A.P.(1998) (70192953)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Nuclear Fusion Reactor / Plasma Facing Materials / Tritium / Multi-Layer Structure / Permeation / Inventory / Erosion / Radiation Damage |
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| Research Abstract |
The permeation and inventory of tritium in a multi-layer divertor were examined under ITER condition by an analytic model taking into account temperature gradient and erosion effect. The erosion accelerated the tritium permeation for both Be/Cu and W/Cu options. Its effect on tritium inventory was, however, significantly different between the former and the latter. In the case of the Be/Cu option1 the tritium inventory in the Be layer dominated the total, and hence the decrease of Be layer thickness due to the erosion resulted in the reduction of the total inventory, In the case of W/Cu option, the tritium inventory gradually decreased initially with the progression of erosion and increased sharply. This distinct behavior was ascribed to the difference in relative magnitude of tritium solubility between Be and Cu, and between W and Cu.
The influence of damaged surface layer on the permeation and inventory of hydrogen was also examined experimentally. The upstream surface of a vanadium membrane (0.1 mm in thickness) was exposed to hydrogen gas at 640 Pa and 673 K, and the steady state of the permeation was attained. Then. the downstream surface of the membrane was irradiated with He ions. No significant variation of the permeation rate was observed in the initial stage of irradiation. The permeation rate, however, started to decrease at the fluence of 10^<21> m^<-2> with further irradiation. This was attributed to the trapping effect on hydrogen diffusion by radiation defects. The irradiation of He ions was intermitted when the permeation rate decreased to a half of the initial value, and then the ion beam was switched on and off repeatedly. The permeation rate increased promptly by the switching-on and decreased by the switching-off These results clearly indicated that the trapping effect under irradiation is small compared with that in the absence of irradiation.
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Research Products
(4 results)
