Operational Characterization of a Combined Electrolysis Catalytic Exchange Process

Abstract

Many current CECE systems, which are used to extract harmful tritium from heavy water nuclear reactors, operate with inefficient alkaline electrolyzers that contain dangerous caustic chemicals. Thus the Hydrogen Isotope Branch at Chalk River Laboratories developed and integrated a safer and more efficient PEM electrolyzer to replace the alkaline electrolyzer. In this research, a bench-scale CECE system with a PEM type electrolyzer at Chalk River Laboratories was tested at LPCE column temperatures of 20°C, 40°C and 60°C to determine baseline operational parameters and conditions for optimal isotopic exchange. Increased operational temperature led to greater isotopic exchange across the PEM electrolyzer but not the LPCE column, an irregularity likely caused by an insufficient amount of catalyst in the column. Increased LPCE temperature also led to a decrease in overall system flow stability. Finally, the PEM electrolyzer voltage exhibited an unusual sharp rise throughout testing, indicating the membrane's susceptibility to damage if used without proper conditioning. Research conclusions will be taken into consideration in setting up a new bench-scale CECE process that more accurately models tritium extraction using a PEM electrolyzer.