AbstractThe fully established flow in the ducts of the outboard segment breeding modules is described as a combination of many sub-channels aligned with the magnetic field and bounded by the cooling tubes. Velocities of the order of kϱG/σB2 are predicted, with k of the order of 10, depending on the subchannel. Much higher velocities are likely to be observed in some regions like the jet flows at the entry, or the 180° bends. An estimation of the turbulence level and of its effects is also proposed.