Tritium measurement techniques for a metal tritide bed in hydrogen isotope storage and delivery system

Nuclear fusion is one of the major alternative energy sources for future society. For this reason, many basic researches have been conducted over half a century, and now seven countries including Korea are carrying out the International Thermo-nuclear Experimental Reactor (ITER) project to evaluate scientific-technologicaleconomic feasibility and effectiveness [1, 2]. The hydrogen isotope storage and delivery system (SDS), which is one of Korea’s procurement packages, must have the function to deliver fusion fuel up to 200 Pa∙m∙s depending on the ITER operating scenario, which changes from time to time. In addition, it should be possible to measure the amount of tritium with an error of ± 3% for 8 to 12 h. Therefore, tritium accounting technologies have been continuously studied and developed for an SDS bed [3, 4]. The pressure, volume, temperature, and concentration method (PVT-c) is a standard tritium accounting procedure. It requires tritium in a gaseous form. It is necessary to heat the SDS bed to keep the tritium in a gaseous form. The tritium release and penetration probabilities might increase if the tritium is kept in a gaseous form. Therefore, tritium accounting technologies without any heating processes have been recommended. Calorimetry, used in the measurement of chemical energy, nuclear half-life, and nuclear material, is one of these techniques. It has been applied to some tritium facilities, providing robust and reasonable results. However, it is difficult to apply typical calorimetry into the SDS bed for ITER because the technique requires an additional SDS bed attaching/detaching system and a thermal measurement facility with large thermal insulation [5]. In this paper, as the tritium measurement techniques without any heating processes, static calorimetry, flowing gas calorimetry, and a radiation measurement were introduced and evaluated to employ into the SDS bed. In addition, our progress on tritium accountability and thermal-hydraulic code application into the SDS is presented.