Development of Pt/ASDBC catalyst for room temperature recombiner of atmosphere detritiation system

Abstract

A combined catalytic reactor and water absorber system has been applied in the field of nuclear fusion to control the tritium release into the environment as low as reasonably achievable. Efficient tritium oxidation performance at room temperature has been strongly required taking a severe accident in a facility into consideration. We have developed hydrophobic Pt catalysts applicable for tritium oxidation in the presence of saturated water vapor at room temperature. A new type of hydrophobic catalyst, Pt/ASDBC, has been prepared by dipositting platinum on alkyl-styrene diviyl-benzene copolymer (ASDBC). Tritium oxidation tests of the catalysts using 3 GBq/m 3 of tritium were performed in the absence/presence of saturated water vapor at room temperature. The overall reaction rate constant for Pt/ASDBC catalyst in the ambient temperature range was considerably larger than that for the traditionally applied Pt/Al 2O 3 catalyst. Oxidation reaction on the catalyst surface is the rate-controlling step in the ambient temperature range. The overall reaction rate constant in the ambient temperature range was dependent on the space velocity and hydrogen concentration in carrier. Values of the overall reaction rate constant in the ambient temperature range were correlated to k overall = 1.60 × 10 5exp(−33.0 (kJ/mol)/ R g/T) (s −1) at the space velocity of 5556 h −1 under the dry condition.