熔盐堆临界能谱与通量分布的仿真计算

Simulation of Critical Energy Spectra and Flux Distribution of Molten Salt Reactor

研究熔盐反应堆在临界工况下的堆芯中子能量和中子通量分布。由于熔盐反应堆的几何结构与目前的热中子反应堆存在很大差异,导致热中子反应堆能谱的求解方法在对熔盐堆进行计算时存在几何处理上的困难。针对上述问题,提出采用具有任意几何处理能力的中子输运计算软件MCNP对熔盐堆堆芯结构进行建模,采用能量区间上的平均通量代替该区间内通量分布的方法,计算了两种熔盐堆在临界工况下的堆芯中子能谱。结果表明,MSBR堆芯能谱为典型的热堆能谱;MOSART堆芯能谱介于快堆能谱和热堆能谱之间。结果能够作为堆芯扩散计算中能量分群方法的依据。同时分析了堆芯内中子通量分布情况,结果表明熔盐堆中子通量分布具有中间高、四周低的特点。

The critical neutron energy spectrum and flux distribution are researched. For the huge difference in structure, the calculation methods of thermal neutron reactor are failed in solving energy spectrum of molten salt reac- tor because of the difficulty in geometry. To solve this problem, this paper puts forward a modeling method by using MCNP, which can solve the problem with complex geometry. Neutron energy spectrums of two types of molten salt re- actor are calculated by using average flux instead of the flux distribution on the energy interval. The result indicates that the energy spectrum in MSBR is a typical energy spectrum of thermal reactor, and the energy spectrum in MOSART is between the energy spectrums of thermal reactor and fast reactor. The result can be used as the basis of multi -group method. And neutron flux distribution is also analyzed. The result shows that the neutron flux distribution of molten salt reactor is large at the center of the core, and small at the edge.