EVALUATION OF HYDROGEN ISOTOPES SEPARATION BY CATALYSED ISOTOPIC EXCHANGE IN LIQUID PHASE

摘要

Due to its high separation factor, the catalytic hydrogen isotopic exchange process between hydrogen gas and liquid water is one of the most desirable processes of tritium separation from gaseous and liquid effluents, produced in fusion and fission reactors. The author's extensive hands-on experience and the thorough literature review provide the foundation for this paper which is an updated overview of the R&D work related to the LPCE development and its application to deuterium and tritium separation technologies. During LPCE process, tritium from tritiated water is transferred to hydrogen gas by the following successive reactions: HTO_((L)) + H_2O_((V)) ?HTO_((V)) + H_2O_((L)) (1) HTO_((V)) + H_(2(G))? HT_((G)) + H_2O_((V)) (2) HTO_((L))+ H_(2(G))? HT_((G)) + H_2O_((L)) (3) The first reactions is in fact a conventional water distillation process that requires the presence of an efficient contact element (hydrophilic packing). The second reaction is only possible in the presence of a hydrophobic catalyst that, while repelling liquid water, allows both gases (H_2) and vapours to reach the active catalytic centres and / thus speeding up the isotopic transfer process. This hydrophilic packing-catalyst mixture labelled as "mixed catalytic packing" is usually used with in LPCE columns under various structures, geometries and ratios. 1. Based on the LPCE process several countries (i.e. Canada, Korea and Romania) developed their own tritium removal facilities while other countries are in the process of developing and implementing similar technologies. The main overview goals are: 1.1 to setup and develop a database to design the best suited mixed catalytic packing; 1.2 o evaluate and propose new ways to improve the LPCE process efficiency; 2. The overview is focused on: 2.1 methods and conditions of hydrophobic catalyst manufacture; 2.2 main types and characteristics of hydrophilic packing; 2.3 structure and internal geometry of mixed catalytic packing; 2.4 water distribution and operation parameters; The present paper proposes several conclusions and general recommendations aimed at the selection of the best suited mixed catalytic packing and operating parameters to improve of the overall efficiency of the LPCE process.