基于柱塞/叠片混合流的放射性微流体萃取——反萃原位耦合系统

The spent fuel reprocessing is a key process of the nuclear power development, in which it is a challenging problem and cries for a solution to selectively separate some valuable nuclides from radioactive liquids. A device to be used to solve the problem must has characteristics such as passive operation, small volume, efficient mass transfer, anti-disturbance, and in-situ coupling of extraction and back-extraction. However, no any device can meet these characteristics to date. In this application, a novel microextractor coupled with back-extraction in situ is designed. A new idea is proposed to establish the novel in-situ coupling system, in which a slug-lamination hybrid flow is formed depended on a partition wall and other structures. The slug-lamination hybrid flow can reduce effects of Kelvin-Helmholtz instability on the continuous interface, and enhance the mass transfer by chaotic advection. The major studies include: (1) effects of microchannel architecture, operating conditions, and physical properties of liquid, and further determination of optimal conditions and flow patterns, (2) performance of mass transfer in the in-situ coupling system, and (3) modelling of the in-situ coupling system. This application aims at a mass transfer equipment available for extreme conditions such as radioactivity and microscale. The research results can solve the key problem in fields of basic research for the spent fuel reprocessing, and consequently has extensive application and broad prospects.

乏燃料后处理是影响我国核电发展的关键环节，其中放射性液体中贵重核素的选择性分离是目前极具挑战和迫切需要解决的难题。解决该难题需要处理设备具有被动式、极小容积、高效传质、抗扰动、萃取——反萃原位耦合这些关键特征，但迄今还没有一种设备能够完全满足。为克服该难题，本申请力求建立新的微流体萃取——反萃原位耦合系统并对其进行研究。新思路为：通过隔离墙等结构创新性地形成柱塞/叠片混合流，降低KH不稳定性对界面的影响并通过混沌对流强化传质。研究内容为：（1）微通道结构、操作条件、物性等的影响规律，确定优化条件和流型分区图；（2）微流体萃取——反萃原位耦合系统的传质性能规律；（3）原位耦合模型研究。本申请提出的微流体萃取——反萃原位耦合系统属于放射性、微尺寸这样的极端和非常规条件下的萃取传质规律和设备研究，是我国乏燃料后处理基础研究领域亟需解决的关键环节，在基础研究和实际生产方面都有广泛的应用前景。

乏燃料后处理是影响我国核电发展的关键环节，其中放射性液体中贵重核素的选择性分离是目前极具挑战和迫切需要解决的难题。解决该难题需要处理设备具有被动式、极小容积、高效传质、抗扰动、萃取/反萃原位耦合这些关键特征，但迄今还没有一种设备能够完全满足。本项目首创了柱塞-叠片混合流，并据此成功地构建了微萃取/反萃原位耦合系统。研究结果为：（1）新型柱塞-叠片流和微萃取/反萃原位耦合系统构建方法；（2）研究了微通道结构、操作条件、物性等的影响规律，确定了优化条件和流型分区图；（3）传质性能规律研究——柱塞-叠片流微萃取/反萃原位耦合系统性能显著高于支撑液膜及三层叠片流系统，并成功示范了柱塞-叠片流系统在Ce、Pr、Cs、Sr四种金属离子的选择性分离中的适用性，进一步证明了该系统在核素样品制备领域的潜力；（4）柱塞-叠片流流场和混合细节的CFD模拟研究——发现柱塞-叠片流的流场存在非对称性，并采用粒子追踪的方法证明了该非对称流场有促进柱塞内部物质交换的作用。柱塞-叠片混合流在乏燃料后处理领域的放射性样品制备、极少量核素选择性回收以及其它化工、生物制药等领域具有极大的应用潜力。