Schematic of Cesium Removal
Demonstration Unit


The Operational Unit

Treatment and disposal options for Department of Energy (DOE) underground storage tank waste at Hanford, Savannah River, and Oak Ridge National Laboratory (ORNL) are limited by high gamma radiation fields produced by cesium in the waste. Treatment methods are needed to remove and concentrate cesium into high-activity, remote-handled waste forms. The remaining liquid could then be processed and disposed of by more cost-effective means with less radiation exposure to workers.

A full-scale demonstration of cesium removal technology, funded jointly by DOE's Offices of Science and Technology (OST) and Environmental Management (EM), was conducted at ORNL. The demonstration system is composed of three compact, skid-mounted modules, one for collecting feed liquids, one for the ion-exchange treatment, and one for dewatering the cesium ion-exchanger. Each module has secondary containment and modular radiation shielding. The effectiveness of the ion exchange material, crystalline silicotitanate (CST), was established in laboratory tests and was developed through a Cooperative Research and Development Agreement between DOE and private industry.

• Ability of CST to selectively remove cesium from acidic to alkaline pH
• Ability to remove trace levels of cesium from 7M NaNO₃
• Modular design for easy setup and remote control operation
• Physical and chemical stability of CST
• Elimination of secondary waste from ion-exchange regeneration
• Cesium-loaded CST can be disposed of at the Nevada Test Site

   Accomplishments include:

• New highly-selected sorbent was developed jointly by the Department of Energy, universities, and private industry
• Successfully took process from laboratory development (10 mL tests) to full scale operation in 2 years
• Successfully demonstrated process by removing 1,000 curies of cesium from 30,000 gal of 5M NaNO₃ using 70 gal of CSTs
• The DOE Savannah River Site successfully vitrified the loaded sorbent for disposal
• Successful demonstration resulted in implementation at ORNL and Savannah River. The process is expected to save over $500M in reduced treatment and waste disposal costs.