# Plasma and Fusion Research

## Volume 7, 2405074 (2012)

# Regular Articles

- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan

### Abstract

Clarification of tritium transfer in blanket is an important issue for realizing fusion reactor.
We perform an experiment of simultaneous H and D permeation through Li_{17}Pb_{83} by means of an unsteady permeation method in order to clarify the interactions and isotope effects between H and D atoms.
The experiment is conducted under the condition where the Sieverts' law holds.
As a result, it is found that (i) H and D atoms permeate independently regardless of the H/D component ratio in the upstream gas and (ii) diffusion process is the rate-determining step in the overall permeation process.
The diffusivity of H is around 1.4 times larger than that of D.
The solubility of H is close to that of D.
We estimate two vibration modes at an absorption site and a saddle point of H in Li_{17}Pb_{83} based on the ratio of isotope effect.
It is considered that the zero-point vibration energy of H at the absorption site in Li_{17}Pb_{83} is around 0.173 eV and that at the saddle point is around 0.235 eV.
The ratio of isotope effect is almost in proportion to the square root of mass ratio of D to H.
The diffusivity of T can be estimated as 1/1.7 times of H.

### Keywords

lithium-lead, liquid blanket, diffusivity, solubility, isotope effect, zero-point vibration energy

### Full Text

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This paper may be cited as follows:

Makoto OKADA, Yuki EDAO, Hiroaki OKITSU and Satoshi FUKADA, Plasma Fusion Res. 7, 2405074 (2012).