The ITER Tokamak Exhaust Processing (TEP) system relies on palladium membrane reactors (PMRs) for tritium recovery. The PMR consists of a palladium/silver membrane permeator filled with a catalyst, that can be used to recover hydrogen species (most importantly tritium) from methane and water impurities present in fusion reactor exhaust emissions. Two superimposed phenomena simultaneously occur inside the PMR: a chemical reaction onto the catalyst liberating hydrogen contained in molecules and permeation of this molecular hydrogen through the membrane. Applying a vacuum on the permeate side allows recovery of pure hydrogen from the molecules (including tritium). The inside-out configuration of the PMR improves vacuum conditions at the permeate side, thus enhancing decontamination factor and tritium recovery performances.
This paper presents the design, construction and initial commissioning of a newly erected test rig at UKAEA to perform experiments with protium on an inside-out PMR prototype in support of the ITER TEP. The efficiency of the PMR is assessed by both measuring flowrate through the permeate gas stream and analysing the composition of the retentate gas stream using gas chromatography. Permeation rate is assessed for protium for flowrates between 10 and 100 ml/min. The methane/water ratio, crucial for methane steam reforming tests, is assessed to optimise decontamination of hydrogen and minimise coking of the PMR. The hydrogen recovery fraction and decontamination factor are assessed for methane and water from flow rates of 10 to 60 ml/min.