Performance of radial fuel shuffling sodium cooled Breed and Burn reactor core

Highlights: • Assembly parameters were optimized from neutronics and thermal-hydraulics. • Core physical properties of different fuel shuffling strategy were compared. • Preliminary thermal-hydraulic analysis of the equilibrium cycle was performed. - Abstract: In this paper, performance of radial fuel shuffling of sodium cooled Breed and Burn reactor core is investigated. Neutronics and depletion calculations are carried out by MCORE based on the ENDF/B-VII data library. Thermal-hydraulic analysis is performed based on a self-developed parallel channels model steady-state code SAST. First of all, the assembly parameters are optimized from neutronics and thermal-hydraulics. The results show that assembly with 127 fuel rods and P/D of 1.12 is the best design. Secondly, the core critical features and radial power peaking factors of the inward and outward fuel shuffling strategy under different fuel shuffling periods are carried out. The results show that k_eff of the beginning of equilibrium cycle (BOEC) and end of equilibrium cycle (EOEC) of both the inward and outward fuel shuffling strategy parabolically vary with the fuel shuffling period. Power peaking factor of the inward fuel shuffling strategy decreases with the increase of fuel shuffling period exponentially, while that of the outward fuel shuffling strategy increases with the fuel shuffling period exponentially. The outward fuel shuffling strategy with shuffling period of 500 days performs better in core critical features and radial power peaking factors. Reactivity coefficients of the optimized core are calculated. Finally, preliminary thermal-hydraulic analysis of the optimized core is performed. The results show that maximum cladding interface temperature and maximum fuel temperature are all within the acceptable limits.