放射性废树脂水泥固化放热效应调控及固化体性能研究

Radioactive waste resin cementation is one of the most concerned key issues in radioactive wastes treatment research field. Framework-filler structure of Sulfoaluminate cement matrix is beneficial to resin particles immobilization; however, high hydration heat of Sulfoaluminate cement and concentrated exothermic phenomenon during cementation results in poor stability of waste forms of large dimension. It is urgent to develop efficient technology for radioactive resin cementation, control the exothermic effect during cementation, and improve the stability and strength of waste forms. In this project, basing on radioactive waste resin cementation using Sulfoaluminate cement blended with activated kaolinite and naphthalene-based water reducer, the cementation formula will be optimized, exothermic effect will be controlled and the core temperature of waste forms will be reduced. The longterm stability of waste forms in disposal environment will be assessed, and cementation mechanism and the leaching mechanism of typical nuclides will be expounded. The research will improve the stability of solidified waste forms, reduce nuclides leachability, and increase the resin loading of waste forms, which will provide theoretical proofs as well as technology fundament for efficient cementation and safe disposal of radioactive waste resin.

放射性废树脂固化技术是放射性废物处理领域关注的热点课题。硫铝酸盐水泥固化体的骨架-填充结构有利于对树脂颗粒的包容固定，但硫铝酸盐水泥水化热高、放热集中，导致其大尺寸固化体安定性不良。因此，亟需开发针对放射性废树脂的高效固化技术，调控固化过程放热效应，改善固化体安定性，保证固化体的强度和长期稳定性。本项目拟采用硫铝酸盐水泥掺加热活化高岭石和萘系高效减水剂固化放射性废树脂，系统优化固化配方，调控固化放热效应，降低固化体中心温度；评价处置环境中固化体的长期稳定性，阐明固化机理；揭示固化体中典型核素的浸出特性和浸出机制。项目将改善放射性废树脂硫铝酸盐水泥固化体的安定性，降低核素浸出，提高废树脂包容量；为废树脂的高效固化及安全处置提供理论支撑和技术支持。

放射性废树脂固化技术是放射性废物处理领域的重要课题，本项目针对普通硅酸盐水泥固化放射性废树脂时包容量低、固化体稳定性差的问题，提出了采用硫铝酸盐水泥掺加热活化高岭石和萘系高效减水剂作为固化基材，用于放射性废树脂的高效固化。研究表明，通过混料设计结合满意度函数法可以实现固化配方的多目标优化，得到的优化配方之一为模拟放射性废树脂：硫铝酸盐水泥：热活化高岭石：萘系减水剂=40：55.8：2.2：2，其水胶比为0.44，模拟废物包容量达到了64%。热活化高岭石中的活性Al2O3和SiO2在水化环境下生成钙矾石、水化硅酸钙和水化铝酸钙等水化产物，有利于固化体的骨架-填充结构的强度发展。铝硅酸盐矿物-硫铝酸盐水泥固化体系促进了对放射性核素的吸附，模拟核素Cs(I)的表观扩散系数De的数量级为10-8 cm2/s，浸出指数L大于6，表明了固化体对核素较好的滞留能力。项目还开展了模拟废树脂进行电化学预处理，可大幅减小树脂体积，有利于后续固化操作。本项目目前发表研究论文六篇，其中SCI收录论文三篇，申请发明专利七项，授权五项；参加国际学术会议六次；培养硕士生八名，其中已有四名获得学位。