The maximum fraction of 3He recoverable from deuterium-based plasmas (to fuel D-3He fusion reactors) is investigated, and optimal plasma conditions are identified. The upper bound to the fraction of 3He recoverable from ignited plasmas is ∼80%, corresponding to one 3He atom per 50 MeV of fusion energy, but recovery efficiency is very sensitive to the plasma energy balance. Effects of enhanced radiation losses, tritium assistance, ion/electron temperature split, plasma temperature and density profiles, and external plasma heating are examined. It appears possible to recover ∼70% of the 3He produced in realistic driven semi-catalyzed deuterium (SCD) plasmas, at 70 MeV per atom. This suggests interesting possibilities for the symbiosis of SCD synfuel factories with satellite D-3He reactors for the generation of electricity.