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

• Published in: Nuclear engineering and design 2024-07, Vol.423, p.113162, Article 113162
• Main Authors: Chen, Zeliang, Gui, Nan, Sun, Yanfei, Yang, Xingtuan, Tu, Jiyuan, Jiang, Shengyao
• Format: Article
• Language: English
• Subjects: Friction coefficient; Graphite; Helium; High temperature; HTGR; Pebble flow
• ISSN: 0029-5493
• DOI: 10.1016/j.nucengdes.2024.113162

•A special facility is designed to imitate environment in HTGR at high temperature.•The friction coefficient of graphite in He and N2 is obtained from the experiments.•In He atmosphere, the friction coefficient of graphite is 0.03–0.17 for T = 25–1100 °C.•In N2 atmosphere, the friction coefficient of graphite is 0.03–0.23 for T = 25–900 °C. 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.