钍基液态燃料熔盐实验堆氙毒分析

Xenon analysis of thorium molten salt experiment reactor-liquid fuel

熔盐堆作为第四代核能系统堆型之一,液态燃料形态的特点使其可以实现在线处理和在线添料。为了提高中子经济性可以利用在线处理的氦鼓泡法,将氦气通入反应堆一回路,去除堆芯内的裂变气体(如Xe、Kr)。基于钍基熔盐液态堆(Thorium Molten Salt Reactor-Liquid Fuel1,TMSR-LF1)概念设计,结合熔盐实验堆(Molten Salt Reactor Experiment,MSRE)氙毒模型,分析了鼓泡法去除氙毒中^(135)Xe扩散规律和去除效率对氙毒的影响,并给出了对应的初始有效增殖因子的变化规律。分析结果表明,虽然存在^(135)Xe会大量向石墨扩散的可能性,但是鼓泡法仍然可以有效去除TMSR-LF1堆芯内的^(135)Xe,减小堆芯毒性,提高反应性。

Background： Thorium molten salt reactor-liquid fuel （TMSR-LF） is a thermal molten salt reactor （MSR） with on-line reproeessing to extract waste and poison elements. Helium bubbling technique is considered to extract waste gas i.e., Xe, Kr, from the reactor core in order to improve neutron economics. Purpose： This study aims to implement the MSRE 135Xe poison model, and apply it on TMSR-LF1 of Shanghai Institute of Applied Physics （SINAP） to estimate xenon poison and effective multiplication factor. Methods： A 135Xe poison model with helium bubbling technique was built based on the molten salt reactor experiment （MSRE） research conducted at the Oak Ridge National Laboratory （ORNL） in the 1960s. Compared with present simulation which ignores the 135Xe diffusion behaviors in the fluid salt and graphite, this model provides a better description for a MSR. The nuclear reaction from Scale6.1 and diffusion process on the MATLAB platform were combined for 135Xe analysis in TMSR-LF1. Results： The result shows that helium bubbling technique can remove 135Xe and reduce xenon poison effectively. Most of 135Xe will stay in graphite. Conclusion： Xenon poison model considering 135Xe diffusion and flow effect is reasonable.