Conversion of Tritium Gas to Tritiated Water by Cement Materials

The catalytic conversion of tritium gas (HT) to tritiated water (HTO) by cement materials is studied by using mortars made of ordinary Portland cement and Portland blast furnace slag cement exposed to HT at concentrations of 3 to 6 × 10⁹ Bq/m³ in air. Within the experimental conditions, no significant difference in the conversion rate is found between the two types of cement. Extended experiments are carried out by using mortars made of ordinary Portland cement to evaluate the catalytic effect of cement materials. The experimental results are explained by a model that assumes that the conversion is dependent on the geometric surface area of the mortars. The mortar surface is found to play an important role in the conversion. The capacity coefficient in mass transfer on the mortar surface and its standard deviation are found to be (4.3 ± 1.4) × 10⁻¹¹ m/s. The mechanism of the conversion reaction is uncertain in this study. The conversion rate of the catalytic effect by the cement materials is compared with the conversion rate by the radioactive decay of T₂. The HTO produced by the conversion is retained in the pore water of the cement materials.