DEVELOPMENT OF HYDROGEN TREATMENT SYSTEM IN SEVERE ACCIDENT (3) STUDY OF REACTANT DIAMETER EFFECT ON HYDROGEN TREATMENT

摘要

The hydrogen treatment system has been developed in order to prevent the overpressure of the primary containment vessel (PCV) caused by a large amount of hydrogen generated by the metal-water reaction in severe accidents (SAs) of Light Water Reactor. In previous studies, we evaluated the hydrogen treatment rate using a couple of metal oxides, and confirmed that MnO_2, CuO, and Co_3O_4 were effective for the hydrogen oxidation under the oxygen-free condition, then we selected them as reactants[l]. Although the reactants were granulated with a diameter of 2 mm for application to the system, the hydrogen treatment rate has not been scarcely evaluated for the granulated MnO_2 which is expected to treat the hydrogen around 120 °C [2]. Thus, we made the diameter of the granulated MnO_2 smaller, and found that the hydrogen treatment was occurred by the granulated MnO_2 with a diameter below 1.0 mm. The granules with a diameter below 1.0 mm were also acceptable for the system from the point of view of decreasing the differential pressure (DP). Moreover, the experiments using a test section simulating a reactor of the system had been conducted under the hydrogen condition simulating typical condition of a SA, by loading the granulated CuO with a diameter of 2mm onto the granulated MnO_2 with a diameter of 1mm. As a result, the hydrogen treatment was markedly accelerated by supplying enough reaction heat from the granulated MnO_2 to the granulated CuO.