熔盐燃料对加速器驱动的次临界堆中子学性能的影响

Study of the neutronics performance of molten salt fuel in an accelerator driven subcritical reactor

加速器驱动的次临界熔盐堆(Accelerator-Driven Subcritical Molten Salt Reactor,ADS-MSR)结合了熔盐堆与ADS的许多优点,在先进核燃料利用方面有独特的优势。为了研究熔盐燃料的使用对ADS系统堆芯的中子学性能的影响,基于MCNP(Monte Carlo N Particle Transport Code)程序,分别计算并分析了熔盐燃料对加速器驱动的次临界堆的外源质子效率、中子能谱以及钍铀转换比等参数的影响。结果表明:相较于氧化物燃料,熔盐燃料的使用将会增加对外源中子和裂变中子的慢化,并且会提高堆芯的入射质子效率。同时,由于熔盐燃料的慢化效应,FLi Be和FLi熔盐燃料燃耗初期的钍铀转换比(CR)分别为1.023和1.062,略低于氧化物燃料的1.068。另一方面,熔盐燃料的在线处理会极大降低燃耗过程中的反应性损失。通过在线燃料处理和在线添料,FLi熔盐和FLi Be熔盐燃料的CR分别在燃耗运行的第1年和第3年超过氧化物燃料,并且能够长期稳定在1.06和1.00左右。

[Background] Accelerator-driven subcritical molten salt reactor（ADS-MSR） has many unique advantages and features for advanced nuclear fuel utilization. [Purpose] This study aims to analyze the influence of neutronics performance of the molten salt fuel in ADS. [Methods] In this work, the Monte Carlo N particle transport code（MCNP） program was employed to calculate the proton source efficiency, the neutron spectrum and the Th-U breeding in an accelerator driven subcritical molten salt reactor. [Results] Molten salt fuels will enhance the moderation to spallation neutrons and fission neutrons while improving the proton source efficiency. The moderating effect of molten salt reduces the Th-U breeding capability at the beginning of burnup, and the CR of FLi, FLi Be and oxide fuel were 1.023, 1.062 and 1.068 respectively. On the other side,with on-line refueling and fuel processing, the CR of FLi and FLi Be salt become higher than oxide fuel in the first year and 3 rd year of the burnup, and can stabilize around 1.06 and 1.00 for a long period of time, respectively. [Conclusion] Compared to the oxide fuel, the FLi molten salt fuel has the better performance on Th-U breeding in an accelerator driven subcritical reactor.