Supported Pd nanoclusters for the hydrogen mitigation application in severe accidents

Abstract Accidents at TMI, USA and Fukushima, Japan have emphasized the need for hydrogen mitigation during nuclear plant accidental conditions, especially during severe accidents which will be no power, massive hydrogen, high temperature, long-term operation, and poisoning environment. Passive autocatalytic recombiners with catalyst sheets are the promising way to deal with the situation in severe accidents. Here we report a new kind of catalyst sheets based on stainless steel supported Pd nanoclusters prepared by electroless deposition route. The catalyst sheets were characterised for morphology and composition of surface by SEM and EDS. The catalytic activity of the catalyst sheets has been evaluated under the conditions of higher temperature, long-term operation and poisoning environments. The catalyst sheets showed high activity and good stability either operating above 500 °C for 24 h or continuous operating for 25 days. For the obtained catalyst sheets after exposed to methanal, iodine vapor and BaSO 4 aerosol respectively with corresponding concentrations higher than SA conditions, the start-up time for H 2 -O 2 recombination reaction was less than 1 min and the catalytic efficiency was more than 90%. These results indicate the potential application of this type of catalyst sheets for hydrogen mitigation in severe accidents.