Influence of graphitization degree of nuclear graphite on HTGR reactor physics calculation

Abstract Nuclear graphite is widely used in traditional and advanced nuclear reactors. Especially in High Temperature Gas-cooled Reactors (HTGRs), nuclear graphite is the main composition of fuel element and reflector. The graphite cross section data libraries used in practical reactor physics calculations are generally evaluated from ideal single crystal graphite material. However, the actual nuclear graphite is not ideal but contains a certain proportion of amorphous carbon, which is measured as graphitization degree. By this short paper, it is shown that the graphitization degree of nuclear graphite has a considerable influence on HTGR reactor physics calculation. The observation would be important for the engineering design of various types of graphite reactors.