Conversion of Low-Concentration Tritium Gas to Tritiated Water

The conversion reaction of tritium gas (T₂) to tritiated water was studied experimentally at initial tritium concentrations between 9.6 × 10⁻³ and 48 GBq · m⁻³ (2.6 × 10⁻⁴ and 1.3 Ci · m⁻³) in air. Effects of water vapor and catalysts on the conversion reaction were also examined. Stainless steel, copper, paint, and platinum black were used as potential catalytic surfaces. First-order rate constants for the reaction in air are found to be independent of initial tritium concentration, and there is no effect from water vapor on the reaction. The conversion is insensitive to the presence or absence of stainless steel and copper. Paint sorbs T₂ and HTO, but the latter is desorbed from the paint by heating. Platinum black produces the expected increase in the rate of reaction.