Experimental Investigation on the Gasification Kinetics of Irradiated A3-3 Matrix Graphite

Abstract Thermal treatment in the atmosphere of carbon dioxide is proved to be a more promising approach to selectively separate C-14, which contributes substantially to the radioactivity of irradiated graphite even after thousands of years, from the bulk of irradiated graphite. Some key factors such as the origin of graphite, the type of reactor and the atmosphere during treatment play significant roles in the thermal treatment. In this paper, irradiated A3-3 graphite was selected to study the gasification reaction kinetics in a range of CO2/Ar/CO gas mixtures. In the absence of CO, the results of gasification reaction rate in different CO2 partial pressure and temperature were presented. In the CO2/Ar/CO mixed gas, the gasification reaction rate in different CO partial pressure was also examined. According to the results of experimental studies, the activation energy value and pre-exponential factor of the global reaction and elementary reactions were obtained. As a conclusion, it is inferred that uniform gas-solid reactions occur on the surface of irradiated A3-3 matrix graphite particles within the temperature range of 975 to 1045°C. The results might be beneficial for the future design of thermal treatment for the selective separation of C-14 from irradiated A3-3 matrix graphite.