Two-way coupling of subchannel T/H code CUPID-RV with neutronics and fuel performance codes for multi-physics simulations of pin-wise PWR core analysis

Recent efforts have focused on developing high-fidelity, multi-physics safety analysis methods to better assess realistic safety margins. However, conservatism remains due to simplified safety analysis, such as applying hot-pin conditions uniformly across the core. This study presents a two-way coupled code for pin-wise reactor analysis by integrating the subchannel-scale thermal-hydraulics code CUPID-RV, the neutron kinetics code MASTER, and the fuel performance code GIFT. The objective is to generate accurate pin-wise fuel rod conditions during normal operation and provide realistic initial conditions for transient analysis. The coupled framework enables detailed thermal-hydraulic analysis with fuel deformation and simulates realistic power distributions with coolant and fuel temperature feedback. The three codes were integrated using socket communication and a dynamic link library (DLL), and a practical steady-state simulation was performed for an OPR1000-type reactor during its first cycle. A control rod ejection transient analysis was then conducted using the pin-wise fuel rod conditions produced by the coupled code. The results show that incorporating detailed fuel rod information, including irradiation history, improves DNBR prediction by 0.01% and enhances the reliability of safety evaluations.