Development of steady analysis model for molten salt fast reactor

Molten salt reactor (MSR), one of the six Generation-IV reactor types in the Generation-IV International Forum, adopts fluoride salt like UF4 or ThF4 as both fuel and coolant simultaneously. A concept of fast-spectrum MSR, molten salt fast reactor (MSFR), was proposed for burning transuranium element. The unique features, such as long neutron free path, weak effect of local-wise resonance self-shielding, delayed neutron precursors movement and strong coupling between neulronics and thermal hydraulics, require new modeling method for MSFR. In this study, a coupled neulronics and thermal hydraulics code named MANTIS was developed by combining Monte Carlo method and deterministic method. MANTIS adopts traditional "two-step" scheme for the neulronics calculation. A Monte Carlo code OpcnMC was used to generate few-group cross section due to its geometric modelling flexibility and arbitrary definition of energy group structure. Multi-group diffusion equations were solved by the variational nodal method, and axial movement of delayed neutron precursor was considered by introducing a convection term to delayed neutron precursor balance equation. Multi-channel thermal hydraulics method was employed for thermal hydraulics calculation. The verification results of ID and 3D model proved that 3D homogenization model satisfied the requirement of MSFR neulronics analysis. Finally, some neulronics parameters of MSFR were calculated based on MANTIS code.