Lule, Senem SenturkSayin, SefaKutbay, FerideBircan, Muhammed MustafaColak, Uner2026-04-252026-04-2520260306-45491873-2100https://doi.org/10.1016/j.anucene.2025.111965https://hdl.handle.net/11486/8252High Temperature Gas Cooled Reactors (HTGRs) offer wide range of applications besides electricity generation therefore different designs are under development with multi-physics modeling. Although neutronic calculations of block type HTGRs are quite straight forward, thermal-hydraulic calculations are challenging due to complex heat transfer mechanism in the core. In addition, if high fidelity is applied, the computational power and time requirement is quite high. The high fidelity, loose, and explicit coupling multi-physics approach with Monte Carlo and computational fluid dynamics codes was proposed in this study that minimizes the computational power need without losing accuracy. The proposed methodology was tested with Holos Quad Core microreactor. The calculations showed that both neutronic and thermal-hydraulic simulation results of the proposed methodology are within 4% difference level with the results given for Holos microreactor therefore showing the proposed methodology's reliability.eninfo:eu-repo/semantics/closedAccessHTGRMulti-physicsHigh fidelityLoose couplingMont CarloCFDArticle22710.1016/j.anucene.2025.1119652-s2.0-105029773502Q1WOS:001611905100001Q10000-0001-8440-6443