  The present work intend to be a first step towards the understanding and
quantification of the hydrogen isotope complex phenomena in liquid metals for
nuclear technology. Liquid metals under nuclear irradiation in,e.g., breeding
blankets of a nuclear fusion reactor would generate tritium which is to be
extracted and recirculated as fuel. At the same time that tritium is bred,
helium is also generated and may precipitate in the form of nano bubbles. Other
liquid metal systems of a nuclear reactor involve hydrogen isotope absorption
processes, e.g., tritium extraction system. Hence, hydrogen isotope absorption
into gas bubbles modelling and control may have a capital importance regarding
design, operation and safety.
  Here general models for hydrogen isotopes transport in liquid metal and
absorption into gas phase, that do not depend on the mass transfer limiting
regime, are exposed and implemented in OpenFOAMR CFD tool for 0D to 3D
simulations. Results for a 0D case show the impact of a He dispersed phase of
nano bubbles on hydrogen isotopes inventory at different temperatures as well
as the inventory evolution during a He nucleation event. In addition, 1D and 2D
axisymmetric cases are exposed showing the effect of a He dispersed gas phase
on hydrogen isotope permeation through a lithium lead eutectic alloy and the
effect of vortical structures on hydrogen isotope transport at a backward
facing step. Exposed results give a valuable insight on current nuclear
technology regarding the importance of controlling hydrogen isotope transport
and its interactions with nucleation event through gas absorption processes.
  Keywords: hydrogen isotopes, permeation, two-phase flow, nucleation, CFD
