Radioactive Waste Treatment Using Cement-Glass Solidification Technique

摘要

A new radioactive waste treatment system has been developed from the viewpoint of minimizing the volume and then solidifying the waste into a stable form. Emphasis has been placed on long term stability in the final disposal environment by solidification using a new inorganic agent (cement-glass). The primary components of the cement-glass are sodium silicate and phosphorous silicate. The mixing of cement-glass powder and water initiates a polymerization reaction by silicates, resulting in a three-dimensional structure of O-Si-O. Since all the materials used for cementglass are naturally produced from clay containing montmorillonite, low cost as well as superiority in long term stability are obtained. Cement-glass is superior to ordinary cement in such points as lower viscosity (about 1/4) and higher adsorption capability of Cs and Sr (about 1060). Many kinds of waste, which have different chemical characteristics, can be solidified by cement-glass due to its inertness towards the waste. The solidification system using cement-glass has been adopted by one BWR and one PWR plants, and the first plant started commercial operation in 1991.