The influence of the extraction of gas/liquid samples on the isotopic separation regime of the CECE process

At National R&D Institute for Cryogenics and Isotopic Technologies (ICSI), in the framework of a research project within the national research program "Core", an experimental installation was created and put into operation for the development of the CECE (Combined Electrolysis Catalytic Exchange) process, both for the separation of tritium in view of waste decontamination and its recovery, and for the separation of deuterium for its recovery in various technological applications. The experimental installation based on the CECE process was made with a Proton Exchange Membrane (PEM) type hydrogen generator (electrolyzer), produced by Hogen company, and a Liquid Phase Catalytic Exchange (LPCE) column equipped with mixed catalytic package manufactured by ICSI. To evaluate the CECE process, several experiments were carried out with a reduced deuterium content (∼2 %) and the tritium concentration around 1000 Bq/l. The isotopic concentrations in the gas and liquid phases were measured at the points of interest of the technological installation during the operating period, by means of sampling extractions on the liquid/gas phase. Since, the isotopic separation process is mainly a non-stationary process, we considered necessary to developed a theoretical analysis regarding the influence of sample extraction frequency on the isotopic separation regime in order to optimize the extraction of gas/liquid samples necessary for monitoring the isotopic separation process. For this, the mathematical model was developed considering also the extractions of samples in the liquid and gas phase at the points where these samples are taken (liquid and gas from the electrolyzer, liquid from bottom of the LPCE column and gas samples at several points along the LPCE column). Experimental data from previous tests were used as well.