Experimental evaluation of tritium oxidation efficiency in the room temperature recombiner

Abstract

To enhance public acceptance of a nuclear fusion reactor, the realization of passive detritiation system is a technical challenge taking hypothetic extraordinary situations occurred in a nuclear fusion facility into consideration. To achieve passive tritium oxidation with a room temperature recombiner (RTR), the hydrophobic platinum catalyst has been realized and data on kinetics have been accumulated. Since the efficiency of hydrogen oxidation at room temperature decreases with a decrease in hydrogen concentration, the worst condition of the process gas for RTR is the lowest hydrogen in the process gas. To overcome this condition, we have proposed to add hydrogen intentionally to be 100 ppm at the inlet of RTR. In this study, the dynamic behavior of a tritium leakage in a 12 m3 simulated room and the detritiation with a RTR was demonstrated to confirm the effectiveness of our proposal considering the worst condition for RTR. Initial tritium concentration in the containment was 1.0 GBq/m3. The flow rate was set to 1.8 Nm3/h. The volume of the hydrophobic platinum catalyst was 1000 cm3. Tritium concentration in the containment smoothly decreased one order magnitude after processing for 900 min. We obtained a prospect that a sufficient hydrogen conversion rate can be secured by adding hydrogen of about 100 ppm. From the kinetics point of view, the required amount of catalyst for a RTR is estimated to be three times that for a heated reactor at 473 K in order to obtain the same conversion efficiency of tritium.