An internal parallel coupling method based on NECP-X and CTF and analysis of the impact of thermal-hydraulic model to the high-fidelity calculations

An internal parallel coupling scheme was developed for the coupling between high-fidelity neutronics code NECP-X and the sub-channel thermal-hydraulic code CTF. A new coupling iteration scheme is proposed based on NECP-X/CTF, in which CTF will run after each transport sweep of NECP-X. The interface is developed for both CTF and NECP-X to transfer data via memory rather than files. Based on the newly developed high-fidelity neutronics/thermal-hydraulic coupling system NECP-X/CTF, the impact of the hydraulic cross-flow model, heat conduction model and gap conductance model was studied by calculating the VERA hot full power assembly and core cases. The numerical results show that the internal parallel coupling method is an effective approach for reactor core coupling simulation for the steady state calculation, the new coupling iteration method is more efficient than the traditional Picard iteration method. The sensitivity analysis demonstrates that the cross-flow and gap conductance are very important in coupling for the neutronics and thermal-hydraulic coupling.