Reactor-permeator for reduction of tritium oxide on iron

Tritiated water (Q2O) is produced during fusion fuel purification or air detritiation. Before recovering the tritium by isotope separation, the Q2O needs to be reduced to form Q2 gas. The reduction of tritiated water on iron is an alternative to electrolysis and gas-shift reactors. It allows a simple, compact, configuration with low tritium inventory. The reactor design incorporates a palladium alloy permeator which extracts the Q2. Tests on a commercial iron-based catalyst showed a high reactivity and no degradation with repeated cycling. The optimum temperature for water reduction was 375-395 degree C, and for iron regeneration using hydrogen, 470-495 degree C. The first prototype reactor-permeator decomposed 9.5 g water in 8 hrs using 210 g iron. The time needed for iron regeneration was reduced to 16 hrs by recirculating the hydrogen. A pilot-scale reactor permeator is now under development: it should be capable of reducing 35 kg of water per year, operating at 1 bar. Attention to the choice of structural materials will minimize tritium carryover into the water produced during regeneration. 7 refs., 2 figs