Crystalline Silicotitanate (CST) is an ion exchange material shown to be highly effective for the separation of radioactive cesium from aqueous tank waste.
Office of Environmental Management
February 10, 2023
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Crystalline Silicotitanate (CST) is an ion exchange material shown to be highly effective for the separation of radioactive cesium from aqueous tank waste. This material has been extensively studied in the DOE complex for the past few decades resulting in a wealth of knowledge regarding the performance and characteristics of the material supporting ultimate disposition. The years of research ultimately resulted in recent deployment of the media at both the Savannah River and Hanford sites for treatment of aqueous tank waste, generating a low-level waste effluent that can be immobilized in either the Saltstone Production Facility at SRS or vitrified as low activity waste (LAW) at the Hanford LAW facility. With the recent deployment of these two systems there is a need to further understand the gaps in the knowledge base related to the characterization of the spent media, particularly as it relates to changes that may occur during storage of the media as it awaits final disposition.
This document summarizes what is known about CST properties that may impact storage, retrieval, and disposal, and identifies areas where additional information is needed related to the characterization of this media. Technology areas discussed include cesium loading, laboratory scale column testing, large scale testing, technology demonstrations, computer modeling, cesium desorption and media decomposition, impact of non-target species, gas generation, dry storage, rheological properties, grinding, retrieval from columns, media vitrification, column design, fullscale column operation and performance, and hydrogen generation during storage. At the end of each descriptive section, any technology gaps are identified. The gaps identified are also summarized and ranked based on priority at the end of the document.