Abstract: [Background] Compared with the molten fluoride salt reactor, the molten chloride salt fast reactor (MCFR) has outstanding advantages in terms of transuranics (TRU) solubility, neutron spectrum and melting point, so it is very crucial to study neutron performances of the MCFR to evaluate its feasibility. [Purpose] This study aims to optimize the composition and reprocessing method of the molten salt to enhance the breeding and burnup performance of MCFR. [Methods] Based on the molten salt reactor reprocessing sequence (MSR-RS), the effect of different carrier salt and starting fuel on burnup performance are analyzed and the composition of molten salt is optimized. Then, off-line batch reprocessing and on-line continuous reprocessing are introduced to improve burnup performance. [Results] After a series of optimization, the burnup-time is extended to 31 a, the burnup level is increased to 210GW·d·t^-1, the production of ²³³U is 8300 kg, and finally 12000 kg of TRU is consumed corresponding to transmutation rate of 62.1%. [Conclusion] NaCl is a more suitable carrier salt for MCFR, and minor actinides (MA) in the TRU also helps to improve the breeding performance. Batch reprocessing can not only achieve great burnup performance but also reduces the requirement for the reprocessing system.

Key words: MCFR, Thorium uranium fuel cycle, Burnup