Exothermic characteristics evaluation of the Pt coated α-Al2O3 catalyst in bed for passive airborne radioactive material reduction system under forced flow conditions

After the severe accident at the Fukushima nuclear power plant, there has been heightened interest in the development of severe accident countermeasures. As part of these efforts, a passive filtration system capable of passive operation during power loss is under development. This paper focuses on evaluating the performance of a catalyst-filled bed designed to create a temperature gradient through exothermic reactions between combustible gases generated during accidents and a catalyst. The temperature gradient facilitates the formation of natural convection within the system, enabling passive operation. The catalytic bed is designed in a bed-type configuration filled with exothermic catalysts. To ensure physical and chemical stability under severe accident conditions, heat resistance tests were conducted using inorganic materials as a base to select an optimized exothermic catalyst. A test apparatus was designed for unit evaluation testing of the catalyst-filled bed equipped with the catalytic bed. Exothermic characteristics evaluation tests were conducted by varying the hydrogen volume fraction and face velocity, measuring heat generation in the catalytic bed under each condition. The correlation between these variables and the heat generation performance of the catalytic bed was determined. These findings will be utilized to inform the design parameters of the passive airborne radioactive material reduction system.