Multi-scale Thermal-hydraulics Methodology and its Application to Marine Small Nuclear Reactor

[Purpose] This study develops a multi-scale analysis method for systematically evaluating thermal-hydraulic behavior and safety of marine SMRs under dynamic marine conditions. [Methods] First, system, subchannel, and CFD codes were modified for marine-specific factors impacting system behavior, component heat transfer, and fuel bundle analysis.

Then, targeted methods for system-level, component-level, and fuel bundle scales were established, with a cross-scale data transmission mechanism enabling multi-scale simulation. [Results] Analysis reveals significant thermal-hydraulic changes under marine conditions, especially periodic oscillations in thermodynamic parameters and enhanced heat transfer coefficients under oscillatory conditions. The study further demonstrates that coupling CFD with system and subchannel codes enhances cross-scale accuracy and data coherence.