In nuclear reactors and spent fuel reprocessing plants, the production of tritiated light water is unavoidable, amounting to thousands of tons annually. The direct discharge of this byproduct into the environment poses significant ecological risks. Consequently, strict tritium emission standards have been established worldwide, propelling the development of detritiation technologies. Among these, combined electrolysis and catalytic exchange (CECE) technology stands out because of its high detritiation factor and mild operating conditions, positioning it as a focal point in global research. This study explores the current state of CECE technology, highlights the three key technologies that underpin it, and addresses the challenges faced in its engineering application, thereby promoting its practical implementation.

CECE technology comprises liquid-phase catalytic exchange (LPCE), electrolysis, and hydrogen-oxygen recombination processes. LPCE technology is instrumental in the operation of CECE technology. The LPCE column, a critical component, operates on complicated principles, and its efficiency is influenced by various factors such as temperature, pressure, and packing material. Research conducted over the years has shed light on the effect of these elements on the performance of LPCE columns. Electrolysis technology serves as the bottom reflux mechanism within the CECE, with alkaline electrolyzers and proton exchange membrane (PEM) electrolyzers as the main devices. Alkaline electrolyzers, characterized by their limited liquid inventory, good tritium radiation resistance, and high operational stability, are widely regarded as mature technologies. Efforts are currently being directed toward increasing gas production capabilities. PEM electrolyzers represent a new area of development. Compared to alkaline electrolyzers, their notable advantage lies in the absence of alkaline electrolytes. However, their susceptibility to tritium poses significant challenges to their widespread application. Hydrogen-oxygen recombination technology is the top reflux technology of the CECE technology, with the recombiner device playing a pivotal role. Recent advancements have seen a transition from hydrophilic to hydrophobic catalysts within the recombiners, coupled with a reduction in the reaction temperature by over 100℃ while maintaining an efficiency rate exceeding 99.9%. Concurrently, theoretical simulations of CECE technology have evolved with the development of models such as two-film mass transfer and three-fluid models, alongside simulation programs such as FLOSHEET and EVIO. These tools have been instrumental in guiding the design of the CECE process by combining theoretical simulations and experimental analyses. With the development of theoretical simulations and key technologies underpinning CECE, several countries have designed processing schemes to remove tritium from tritiated light water using CECE technology. This study details the process proposed by Canada and Japan.

Advances in the key technologies of CECE demonstrate significant advantages in removing tritium from tritiated light water. Moreover, there is substantial potential for further development in engineering applications. Furthermore, the efficiency and cost-effectiveness of CECE technology can be further improved in several ways: the development of more efficient and economical catalysts, the enhancement of PEM electrolyzers to offer better resistance to tritium irradiation, increased gas production, and advancements in hydrogen fuel cell technology.