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 Portl and cement and Portland blast furnace slag cement exposed to HT at con centrations of 3 to 6 x 10(9) Bq/m(3) 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 cata lytic effect of cement materials. The experimental results are explain ed by a model that assumes that the conversion is dependent on the geo metric surface area of the mortars. The mortar surface is found to pla y an important role in the conversion. The capacity coefficient in mas s transfer on the mortar surface and its standard deviation are found to be (4.3 +/- 1.4) x 10(-11) m/s. The mechanism of the conversion rea ction is uncertain in this study. The conversion rate of the catalytic effect by the cement materials is compared with the conversion rate b y the radioactive decay of T-2 The HTO produced by the conversion is r etained in the pore water of the cement materials.