Sensitivity Analysis and Dimensioning of Reactor-Scale Pd/Ag Permeators for the Tritium Extraction and Removal System of the EU-HCPB Blanket

One of the reference technologies for the fuel cycle of fusion machines is Pd/Ag membranes. This technology is proposed to be implemented in tritium recovery systems because of their exclusive selectivity toward molecular hydrogen isotopes (Q = H, D, T). To perform scaling-up studies for the Tritium Extraction and Removal System of the European DEMOnstration fusion power reactor (DEMO) with a solid blanket, a one-dimensional simulation code was recently developed and successfully validated with experiments. This code relies on different operational (e.g., feed pressure and temperature), geometrical (e.g., permeator length), and membrane-intrinsic (e.g., Q₂ permeability) parameters given as input. The main outcome is the Q₂ permeation efficiency, defined as the Q₂ permeate–to–feed flow ratio. Because of the low concentrations of Q₂ expected at the He stream purging the solid blanket, the surface effects are expected to be important, decreasing the separation efficiency of the Pd/Ag permeators. In this paper the role of surface effects on the permeation efficiency is studied for a DEMO-relevant scenario (feeding mixture: HT/H₂/He). Moreover, a sensitivity study is also given demonstrating the high impact of the permeation area, temperature, and feed pressure on the permeation efficiency of HT.