Preliminary analysis of fuel cycle performance for a small modular heavy water-moderated thorium molten salt reactor

Heavy water-moderated molten salt reactors(HWMSRs)are novel molten salt reactors that adopt heavy water rather than graphite as the moderator while employing liquid fuel.Owing to the high moderating ratio of the heavy water moderator and the utilization of liquid fuel,HWMSRs can achieve a high neutron economy.In this study,a large-scale small modular HWMSR with a thermal power of 500 MWth was proposed and studied.The criticality of the core was evaluated using an in-house critical search calculation code(CSCC),which was developed based on Standardized Computer Analyses for Licensing Evaluation,version 6.1.The preliminary fuel cycle performances(initial conversion ratio(CR),initialfissile fuel loading mass,and temperature coefficient)were investigated by varying the lattice pitch(P)and the molten salt volume fraction(VF).The results demonstrate that the temperature coefficient can be negative over the range of investigated Ps and VFs for both 233U-Th and LEU-Th fuels.A core with a P of 20 cm and a VF of 20%is recommended for 233U-Th and LEU-Th fuels to achieve a high performance of initial CR and fuel loading.Regarding TRU-Th fuel,a core with a smaller P(~5 cm)and larger VF(~24%)is recommended to obtain a negative temperature coefficient.

新型重水慢化熔盐堆堆芯优化设计

采用液态燃料及重水慢化剂的重水慢化熔盐堆(Heavy Water moderated Molten Salt Reactor,HWMSR)具有高中子经济性,但堆芯出口温差较大,将会导致堆芯顶部管道构件热疲劳。本文旨在优化HWMSR堆芯设计,降低堆芯出口温差。采用中子学-热工耦合程序以及堆芯临界搜索程序,深入分析了具有不同熔盐通道半径堆芯的功率分布、熔盐出口温度分布、初始易裂变核素233U装载量及钍铀增殖等性能。结果表明:增大堆芯内区熔盐通道尺寸将降低燃料熔盐功率密度峰值及最大出口温度,而对钍铀增殖比及^(233)U初始装载量影响非常有限。本研究为优化重水慢化熔盐堆堆芯设计提供参考。