Isotope Effects of Hydrogen Isotope Absorption and Diffusion in Li_0.17Pb_0.83 Eutectic Alloy

Abstract

Rates and amounts of absorption and desorption of hydrogen and deuterium in a Li_0.17Pb_0.83 eutectic alloy are determined under the conditions of temperature of 400-700°C and the upstream H₂ or D₂ partial pressure of 10³Pa-10⁵ Pa by using a one-dimensional permeation pot. Because of small interaction between the alloy and dissolved atoms of hydrogen isotopes, the temperature dependence of the Sieverts’ solubility constant for the Li_0.17Pb_0.83 -H or -D system, i.e., the enthalpy change of absorption or desorption, is small, and the absolute value of D solubility is higher than that of H. The isotope effect of diffusivity between H and D is very small. The generation rate and inventory of tritium (T) in a fusion blanket is estimated under an assumption of one-dimensional Li_0.17Pb_0.83 blanket system with a constant and uniform neutron flux.