Dynamics analysis of the graphite-moderated channel-type molten salt reactors based on Serpent/NTH3D-MSR

The special characteristic of the Molten Salt Reactors (MSR) is that the liquid molten salt mixtures, acting like a coolant and fuel, are flowing through the core and the primary circuit. The delayed neutron precursors are driven by the fuel flow, which results in unique neutron dynamics characteristics of the MSR. The coupled neutronics and thermal-hydraulics code for MSR named NTH3D-MSR has been developed in this paper to simulate the dynamics characteristics of the MSR. In this code, the Predictor-Corrector Improved Quasi-Static (PC-IQS) method and the Nodal Green's Function Method (NGFM) were adopted to solve the neutron kinetics equation and neutron diffusion equation respectively, and the multi-channel thermal hydraulic model is developed to consider the thermal feedback. In addition, the few-group constants of the graphite-moderated channel-type molten salt reactor are generated by the continuous-energy Monte-Carlo code Serpent which can provide remarkable geometry flexibility against the deterministic lattice transport codes. In order to verify the NTH3D-MSR code, the experimental data collected in the European project MOST are adopted to validate the coupled neutronics and thermal-hydraulics model of the NTH3D-MSR code. The numerical results indicate that the Serpent/NTH3D-MSR code has the capability for the dynamics analysis for the graphite-moderated channel-type molten salt reactors.