用聚氨酯固化废闪烁液及固化体的组成、结构和性能研究

The disposal of radioactive waste is one of the key problems for the development of nuclear power. One of the most difficult tasks is to dispose of radioactive organic liquid wastes. The used cocktail for liquid scintillation counting (LSC) is a common kind of radioactive organic liquid waste. At present there is no proper method for the treatment of used LSC cocktails, which have been accumulating more and more, so it is urgent to find an effective method to deal with the used LSC cocktails. This project is planning to present a method of plastic solidification for the used LSC cocktail using polyurethane which has more special properties. The solidification of a common cocktail, which is available commercially, will be studied with the so-called "liquid polyurethane in situ solidification" method. The study will focus on the interrelationships among the compositions of polyurethane, the structures of solidified waste and their basic properties such as mechanical properties, anti-leaching properties, and anti-aging properties. Based on the investigation into the microscopic distribution of LSC cocktail embedded in polyurethane, this project will explore the aging mechanism of the solidified waste and aging effects on the structures and properties of the solidified waste. This project is aiming to establish a solidification method for used LSC cocktail with polyurethane, to reveal the interrelationships among the compositions of polyurethane, the structures of solidified waste and their basic properties. It is expected to clarify the aging mechanism of the solidified waste, to lay a good foundation for further research on solidification of real used LSC cocktail with polyurethane, and to provide a train of thought for the treatment of other kinds of radioactive organic wastes.

放射性废物处理是核能发展所面临的关键问题，其中放射性有机废液是最难处理的废物之一。废闪烁液是一类常见的放射性有机废液，由于目前暂无妥善的处理方法，而且废闪烁液已越积越多，因此如何有效处理废闪烁液已成为亟待解决的问题。本项目拟利用聚氨酯的特有性能，采用"液态聚氨酯原位固化"方法，针对目前常见的商品闪烁液，开展废闪烁液塑料固化基础研究，主要研究聚氨酯组成-固化体结构-固化体性能（机械性能、抗浸出性能、抗老化性能等）之间的关系，研究闪烁液包覆于聚氨酯中的微观分布状态，探索固化体的老化机理及其对固化体结构和性能的影响规律。通过本项目研究，建立一套用聚氨酯固化废闪烁液的方法，揭示聚氨酯组成-固化体结构-固化体性能之间的相互关系，并有望阐明固化体老化机理，为将来进一步研究用聚氨酯固化实际废闪烁液打好基础，同时也为其它放射性有机废液的处理提供一条思路。

放射性废物处理是核能发展所面临的关键问题，其中放射性有机废液是最难处理的废物之一。废闪烁液是一类常见的放射性有机废液，由于目前暂无妥善的处理方法，而且废闪烁液已越积越多，因此如何有效处理废闪烁液已成为亟待解决的问题。. 针对目前常见的商品闪烁液OptiPhase HiSafe 3，本项目采用“液态聚氨酯原位固化”方法，开展了废闪烁液塑料固化基础研究。首先研究了固化配方和固化工艺，在此基础上确定了用聚氨酯固化废闪烁液的三个步骤：70℃预聚（MDI和PTMG-650）、常温预混（废闪烁液、BDO和TEOA）、常温聚合（前两步得到的混合物料）。其次，重点研究了不同固化条件下固化体的抗浸出性能和机械性能。再次，通过Co-60辐照对部分固化体进行加速老化，研究了固化体抗老化性能。最后，研究了废闪烁液包覆于聚氨酯中的微观分布状态。. 结果表明，采用合适固化条件得到的聚氨酯固化体具有牢固的网状结构，而废闪烁液以微液滴的形式均匀分散在这些网状结构中。聚氨酯固化废闪烁液的机理包括物理作用（机械固封、物理吸附）和化学作用（配位作用与化学吸附）两个方面。机械固封的作用体现在两个层次上：第一个层次，阻止浸出剂与网状结构内的包容物接触；第二个层次，当网状结构内的包容物已暴露于浸出剂中时，仍然能阻止废闪烁液微液滴进入到浸出剂中。在常温水介质中，聚氨酯的网状结构不易被破坏，可以有效阻止固化体中Nd、Sr、Cs等元素的浸出。当老化程度与1.01E+06 Gy辐照剂量相当时，固化体老化对固化体抗浸出性能没有明显不利影响。. 本项目研究结果揭示了聚氨酯组成-固化体结构-固化体性能之间的相互关系，为将来进一步研究用聚氨酯固化实际废闪烁液打下了良好基础，同时也为其它放射性有机废液的处理提供一条思路。