A 2D finite element modelling of tritium permeation for the HCLL DEMO blanket module

A local finite element modelling of the tritium permeation through the HCLL breeder unit cooling plates is presented. The tritium concentration in the helium and in the lithium lead are evaluated by solving partial differential equations governing the tritium balance, the thermal field and the lithium lead velocity field in a simplified 2D-geometrical representation of the breeder unit at the mid-equatorial plan. Using a factorial design at two levels as numerical experiments it is shown that the magnetic field and the natural convection are not relevant for the estimation of the permeation. Moreover, numerical analyses showed a developed concentration boundary layer acting as a mass transfer resistance which is equivalent to a PRF of 30.