ThorCon堆氚产额分析研究

Issues in the calculation of the tritium production in the ThorCon reactors

ThorCon堆是一种以熔融氟盐(Na F-Be F2-Th F4-UF4)作为燃料及冷却剂、石墨为慢化剂的小型模块化熔盐反应堆。在热中子的照射下熔盐中的Be、F以及屏蔽层和石墨中的B会发生核反应产生氚。氚在高温下具有很强的渗透能力,能够影响金属构件的力学性能,减少其使用寿命。进入环境的氚在高温下易氧化为氚化水。氚化水进入人体后会形成内照射,对操作人员健康造成影响。根据产氚反应的性质及中间产物个数可将产氚反应分为三类:直接产氚反应、有中间产物的产氚反应、三裂变产氚反应。并对这三类反应分别建立相应的计算方程。计算结果表明,ThorCon堆年产氚约为5.444 g。其中Be反应产氚是最主要的氚来源,88.5%的氚来源于Be。如能降低Be含量,将大幅降低氚的产额。

[Background] ThorCon reactor is a thermal reactor using molten salt （NaF-BeF2-ThF4-UF4） as fuel and coolant and graphite as moderator. Tritium would be produced by nuclear reaction of Be, F in NaF-BeF2-ThF4-UF4 and B graphite, which has strong penetration ability at high temperature, affecting the mechanical properties of the structure and reduce its life. And the tritium is easily changed into trialed water, which may enter the human body, causing internal radiation. [Purpose] This paper aims to predict the production of tritium and its main reaction. [Methods] The tritium production reaction was divided into three types based on the number of intermediate products in the reaction channel, such as producing tritium by nuclear reactions with or without intermediate products and by ternary fission. Three corresponding equations were set up accordingly. [Results] The results showed that the annual tritium production was about 5.444 g, and 88.5% of tritium came from Be. [Conclusion] If the amount of Be can be reduced, the yield of tritium will be greatly reduced.