Analysis of Simultaneous H and D Permeation through Lithium-Lead

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.

Hydrogen solubility and electrical resistivity measurements of hydrogenated Pb-Li

“…Among the others, the transport properties of the hydrogen isotopes in breeders materials are of interest for the tritium control and confinement. In the last 20 years, a large work has been carried out in order to determine the tritium diffusivity and solubility in the Pb-Li alloys [1][2][3][4][5][6][7][8][9]. A recent review work reported the incoherence of the literature data about the hydrogen isotopes solubility [10].…”