高温におけるトリウムと黒鉛の反応に関する研究

抄録

The reaction of thorium metal with graphite was studied in the temperature range of 900°∼1600°C. It was found that the reaction rate was parabolic, and the activaion energy for the reaction was 53 kcal/mole below 1200°C. Marker experiments showed that the growth of carbide film was caused mainly by the migration of carbon. From these results,the rate determining process of the reaction seems to be the diffusion of carbon in the carbide film formed on the metal surface. Hydrocarbons, yielded by hydrolysis of the carbide film, were analysed by gas chromatographic method, from which the ratio of ThC/ThC₂ in the carbide film was determined. The film formed below 1200°C was composed of ThC only. However, in the film formed above 1300°C the ratio of ThC/ThC₂ decreased with increasing temperature. The activation energy for ThC₂ formation was 140 kcal/mole. The diffusion coefficient of carbon in ThC was calculated from the parabolic rate constants. The amount of thorium carbide, which would form in a thorium blanket of graphite matrix fuel reactor, was estimated.