Experimental study of friction coefficient of graphite for high-temperature gas-cooled reactors

Abstract

High-temperature gas-cooled reactors, as highly regarded fourth-generation reactors, extensively utilize graphite materials. It is necessary to perform a study of the characteristics of the graphite materials aiming at optimizing the structural design and neutron physics calculation for the reactor. Thus, the investigation of the graphite friction coefficient is a crucial aspect of the research. This paper presents experiments on the graphite friction coefficient conducted using a specially designed experimental device that closely replicates the operational conditions of high-temperature gas-cooled reactors. The experimental data on the graphite friction coefficients under various atmospheric and temperature conditions are obtained. The graphite friction coefficient under a helium atmosphere demonstrates an initial increase followed by a decrease with rising temperature, reaching a maximum value of 0.17 at 200 °C. However, beyond 400 °C, the friction coefficient stabilizes gradually and fluctuates within the range of 0.03 to 0.06. Under a nitrogen atmosphere, the graphite friction coefficient exhibits the same temperature-dependent pattern as observed in helium. The peak value likewise occurs at 200 °C, measuring 0.23. At temperatures below 400 °C, the graphite friction coefficients in a nitrogen atmosphere surpass those in helium. While beyond 400 °C, the friction coefficients in a nitrogen atmosphere likewise fluctuate within the range of 0.03 to 0.06.