【作者】 范芳丽； 王洁茹； 杨帆； 秦芝；

【Author】 Fang-Li Fan;Jie-Ru Wang;Fang Yang;Zhi Qin;Institute of Modern Physics, Chinese Academy of Sciences;Xiamen Institute of Rare-earth Materials, Haixi Institute, Chinese Academy of Sciences;

【机构】 中国科学院近代物理研究所； 中国科学院海西研究院厦门稀土材料研究所；

【摘要】 乏燃料中的裂变产物稀土元素对热中子俘获截面特别大,在反应堆中随著量的积累会消耗大量的中子,成为中子毒物。此外稀土元素在燃料元件中还会降低二氧化铀的导热率。为了更好地利用乏燃料,提高二氧化铀的导热率,有必要将这些稀土元素除去。目前在乏燃料的后处理过程中,都是通过溶剂萃取的方法除去稀土元素,但是这样会产生大量的废液,同时还需要对Pu转换提供严格的防护措施。为了提高乏燃料的使用率,减少核废物的处置,本课题提出利用固-固相分离替代传统的液相分离,将乏燃料中的稀土元素有效除去,为乏燃料的后处理提供了另一种技术路线选择。。我们计划通过两种技术路线来实现乏燃料中的中子毒物（稀土元素）的分离。1)高温氧化分离:利用稀土元素和氧化铀在高温下重新结晶产生的颗粒大小和形貌不同,用筛分、空气分离、沉积等技术将富稀土相的小颗粒和贫稀土相的大颗粒分开。2)离子液体浮选分离:选择油酸和离子液体作为浮选介质,其中油酸相溶解了可捕捉稀土化合物的捕捉剂,经过多次浮选分离后,U₃O₈处于下层,稀土氧化物处于上层,从而达到从氧化铀粉末中分离稀土元素的目的。更多还原

【Abstract】 As a major fission product generated by nuclear reactions, rare earth elements, were neutron poison due to their large neutron absorption cross-section. Because they can absorb neutrons in nuclear reactors, their accumulation will have an impact on the continual operation of nuclear reactors. Hence, it is necessary to remove these rare earth elements from spent nuclear fuel for advanced nuclear fuel cycling. In this work, two methods were introduced to remove rare earth elements from simulated spent nuclear fuel. One is oxidation separation at high temperature. This process results in the segregation of the spent fuel into a rare earth-rich phase and a rare earth-poor U3O8 phase. The other method is flotation process. Flotation system was constituted by suitable ionic liquid, oil acid and capture agents for rare earths oxide. U3O8 and rare earths oxide will not be dissolved in these liquids during the flotation experiment. Rare earths oxide will be removed from the mixture and the amount will be minimized after several flotation cycles. The more detail experiments are ongoing in our laboratory.更多还原