A Status Update and the Development Progress of the HTR Code Package

As a critical component of the energy sector, the high-temperature gas-cooled reactor (HTR) system plays an important role on the road to carbon neutrality. As a flagship of the safety analysis codes, the HTR code package (HCP) has been developed to provide a comprehensive modeling and simulation platform of the HTR system under operational and accidental conditions, especially for pebble bed reactors. A variety of individual legacy HTR computer codes were integrated into a consistent code package using flexible and efficient programing techniques and standards, and the know-how gained over decades in HTR safety studies was preserved. This paper gives a state-of-the-art overview in HTR studies and presents the new flexible curtain-based control rod system that has been recently implemented. This method involves flexible manipulation of isotope concentrations and utilizes C++ object-oriented programing principles while incorporating the legacy codes. Comparative analyses with established codes such as Serpent and ATHLET underscore the precision and reliability of the HCP, thereby enhancing its applicability in HTR design and safety evaluations. Finally, the paper outlines prospective avenues for further advancing the HCP, underscoring its evolving role in shaping the future of HTR development and analysis.