Versatile chemical handling to confine radioactive cesium as stable inorganic crystal

Abstract

The present paper describes an extremely efficient, reproducible and inexpensive chemical handling method for converting the nuclear wastes contaminated by radioactive cesium to stable inorganic crystal, pollucite (CsAlSi2O6), which is promising as a form of the final storage. In this processing, the clays are used as a source for aluminum and silicon, and it is important to get a well-mixed homogenous solution by the aid of some heat and pressure. The present method proposes the use of ethylene glycol as a solvent, rather than water. It has been found that one can obtain crystalline pollucite by heating up to 350 °C in a high-pressure container (~15 MPa), mixed with montmorillonite – an abundant natural clay and ethylene glycol. It has been found that the reduction of the amount of water helps to achieve very high confinement rate in a reasonable time of few~20 h. This will be fairly important in processing contaminated water in the nuclear power plant. The influence of seawater has been also examined.