Park Hwan-Seo, Kim In-Tae, Kim Hwan-Young, Ryu Seung-Kon, Kim Joon-Hyung
Nuclear Fuel Cycle R&D Group, Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon, 305-353, Korea.
Environ Sci Technol. 2007 Feb 15;41(4):1345-51. doi: 10.1021/es0615472.
The volatilization of radionuclides during the stabilization/solidification of radioactive wastes at high temperatures is one of the major problems to be considered in choosing suitable wasteforms, process, material systems, etc. This paper reports a novel method to convert volatile wastes into nonvolatile compounds via a sol-gel process, which is different from the conventional method using metal-alkoxides and organic solvents. The material system was designed with sodium silicate (Si) as a gelling agent, phosphoric acid (P) as a catalyst/stabilizer, aluminum nitrate (Al) as a property promoter, and H20 as a solvent. A novel structural model for the chemical conversion of molten salt waste, named RPRM (Reaction Product in Reaction Module), was established, and the waste could be solidified with glass matrix via a simple procedure. The leached fraction of Cs and Sr by a PCT leaching method was 0.72% and 0.014%, respectively. In conclusion, the RPRM model isto converttargetwastes into stable and manageable products, not to obtain a specific crystalline product for each radionuclide. This paper suggested a new stabilization/solidification method for salt wastes by establishing the gel-forming material system and showing a practical example, not a new synthesis method of stable crystalline phase. This process, named "gel-route stabilization/solidification (GRSS)", will be a prospective alternative with stable chemical process on the immobilization of salt wastes and various mixed radioactive waste for final disposal.
在高温下对放射性废物进行稳定化/固化过程中，放射性核素的挥发是选择合适的废物固化形式、工艺、材料体系等时需要考虑的主要问题之一。本文报道了一种通过溶胶 - 凝胶工艺将挥发性废物转化为非挥发性化合物的新方法，该方法不同于使用金属醇盐和有机溶剂的传统方法。所设计的材料体系以硅酸钠（Si）作为胶凝剂，磷酸（P）作为催化剂/稳定剂，硝酸铝（Al）作为性能促进剂，水（H₂O）作为溶剂。建立了一种用于熔盐废物化学转化的新型结构模型，称为RPRM（反应模块中的反应产物），通过简单的程序可将废物与玻璃基质固化。采用PCT浸出法时，Cs和Sr的浸出分数分别为0.72%和0.014%。总之，RPRM模型是将目标废物转化为稳定且易于管理的产物，而非针对每种放射性核素获得特定的结晶产物。本文通过建立凝胶形成材料体系并给出实例，提出了一种盐废物稳定化/固化的新方法，而非稳定结晶相的新合成方法。这个过程，称为“凝胶途径稳定化/固化（GRSS）”，将是一种在盐废物和各种混合放射性废物固定化最终处置方面具有稳定化学过程的前瞻性替代方法。
