NECP-panda: A neutronics and thermal-hydraulic analysis code for pebble-bed high temperature gas-cooled reactor

As one of the fourth-generation nuclear energy systems, the Pebble-Bed High Temperature Gas-cooled Reactor (PB-HTGR) shows promising prospects. Aiming to address the emerging requirements in the design analysis and technological improvement of the PB-HTGR core, the Nuclear Engineering Computational Physics (NECP) Laboratory of Xi'an Jiaotong University is autonomously developing a neutronics and thermal–hydraulic analysis code named NECP-Panda. The development work pertaining to the steady-state neutronics calculations for the reactor core has been successfully completed. This paper presents the computational framework of NECP-Panda, focusing on the theories and methodologies of neutronics calculation. Based on the model of the High Temperature Reactor Pebble-Bed Module (HTR-PM) in China, NECP-Panda conducted initial fuel loading calculations and absorber worth calculations. Numerical results demonstrate a high consistency between NECP-Panda's critical loading height prediction for HTR-PM and the Monte Carlo (MC) continuous energy calculation results, with the number of loading pebbles at criticality closely approximating experimental result. Moreover, reactivity worth for various absorber combinations and control rod integral worth curves show satisfactory agreement. NECP-Panda demonstrates exceptional computational capabilities, accuracy and acceptable efficiency in neutronics calculations for the PB-HTGR, laying a solid foundation for the subsequent development of other modules.