Development of cross-section calculation module for high-temperature gas-cooled reactor engineering simulator system using an optimal model tree algorithm

•A more accurate cross-section calculation model is required for real-time simulation.•A machine-learning-based cross-section calculation model is proposed.•The proposed method produced accurate cross-section and reactor physics results.•It also met the engineering simulator system real-time calculation requirements.•Under different operating conditions it conformed to the reactor laws of physics.