Gas separation by a Pd-plated alumina membrane for a small-scale emergency atmospheric detritiation system

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I conducted an experiment of the hydrogen and water vapor separation by a Pd-plated alumina membrane for a small-scale emergency atmospheric detritiation system (ADS) and carried out numerical simulations of an integrated ADS.The following results were obtained.(1) Water vapor and hydrogen separation characteristics were numerically simulated for the case of an integrated ADS partially replaced by the gas separation membrane. The counter-current flow was found to be the most promising among the cross flow, counter-current flow, co-current flow and complete mixing flow from a viewpoint of the gas separation efficiency of ADS.Water vapor preferentially permeated near the inlet of the gas separation membrane for the case of the three-component system of water vapor, tritium and nitrogen. The best cut condition was determined.(2) The water vapor and hydrogen permeabilities of a cellulose-acetate membrane and a polyimido membrane agreed with values reported in the past elsewhere. This results shows a good performance of the experimental apparatus built here.(3) Electroless Pd plating on Zr_2Fe particles was conducted for the investigation of the hydrogen permeation performance of a Pd film. The Pd plating was stable even in heating up to 800ﾟC.Hydrogen effectively permeated through the Pd film at around room temperature in oxygen free atmospheres, while hydrogen gas changed to water vapor on Pd film in atmospheres including oxygen.(4) Mist formation occurred in gas streams at the critical supersaturation condition when water vapor permeating through the gas separation membrane of ADS was cooled for desublimation from the streams.In order to establishe a small-scale emergency atmospheric detritiation system, the gas separation membrane, the electroless Pd plating technique and the vapor desublimation system was integrally investigated and each system component was proved to perform expected characteristics.