Plasma Enhancement Gases (PEGs) separation through inorganic membranes

The exhaust gas in the tokamak demonstration reactor (DEMO) consists of more than 80% of unburned fuel gas (D and T) and with the balance being He, plasma enhancement gases (PEGs), and impurities. Plasma enhancement gases (PEGs) (such as: nitrogen, neon, argon and other inert gases) are injected into the plasma to reduce the power load over the plasma facing component. In the demonstration reactor (DEMO), it is foreseen that it will be necessary to recover the fuel gas (D and T) and PEGs. For the DEMO exhaust processing system, the use of inorganic membranes has been recently taken into consideration. The research focuses on the removal of PEGs from He and the fuel gas using inorganic membranes at a fusion reactor plant. Hence, the heart of the research is to test potential inorganic membranes to achieve this goal. Several inorganic membranes have been acquired and tested after having contacted various universities and industries all around the world. A permeation test rig built by dr. E. Serra in ENEA Casaccia has been used to test porous membranes and verify their gas separation efficiency. The best PEG separation and recovery results were obtained with a carbon molecular sieve membrane (CMS) at 250 °C. The measured permeances and selectivities of gases can be used for the conceptual design of the PEGs purification system. Finally, gas transport mechanisms through porous membranes are investigated.