Development of new type passive autocatalytic recombiner. Part 1. Characterization of monolithic catalyst

For hydrogen mitigation, a new type passive autocatalytic recombiner has been developed, as one of safety accident managements at a nuclear power plant. This new recombiner has an automotive monolithic substrate catalyst in order to reduce weight and to improve hydrogen treating capacity, environmental resistance, and product quality. The activation energy has been experimentally estimated at 5.75 kJ/mol with stoichiometric composition gas flow. The fed hydrogen and oxygen to the monolithic catalyst were immediately recombined in both the dry and the humid atmospheres. Moreover, it has been found that gamma-ray irradiation up to 1.0 MGy could promote catalytic activity, because the specific area of the catalyst and the surface area of the precious metals increased. In addition, no significant difference was observed in the compositional distribution in the monolithic catalyst by EPMA. As the result, an automotive monolithic catalyst is applicable to practical installation of PAR into NPPs. (author)