Treatment of tritium in off-gas by catalytic oxidation

The gaseous tritium (HT, DT or T2) is contained in off-gas from research reactors, nuclear power plants that use heavy water and tritium-handling facilities. This off-gas has been usually released to the environment without removal of tritium because the tritium concentration is low enough to satisfy the permissible release concentration specified in regulation. However, as the regulation tends to be strengthened for increasing the safety more and as the generation of offgas containing relatively high concentration of tritium is also expected due to the expansion of the use of tritium in nuclear industry, it is recently being recognized that the treatment of off-gas containing tritium is important. The tritium in off-gas is usually treated by two steps. It is first oxidized to tritiated water vapor by a catalyst and then the vapor is adsorbed in a molecular sieve drier. Conventionally the oxidation is carried out by using catalyst in a temperature range of 150∼200 .deg. C. which is high to adsorb directly the tritiated water vapor in molecular sieve. And other approaches have been employed to oxidize the tritium in off-gas at ambient temperature. In the experiments, as a preliminary study of the treatment of tritium in off-gas, the oxidation of hydrogen in air is investigated at room temperature by using two kinds of catalysts which are a precise metal catalyst supported on polymer and another precise metal catalyst supported on alumina