Development of the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) Process for Cesium Removal from High-Level Tank Waste

Conference · Sat Jan 01 04:00:00 EST 2011

OSTI ID:1024251

Moyer, Bruce A ^[1]; Bonnesen, Peter V ^[1]; Delmau, Laetitia Helene ^[1]; Williams, Neil J ^[1]; Birdwell, Jr, Joseph F ^[1]; Lee, Denise L ^[1]; Leonard, Ralph ^[2]; Fink, Samuel D ^[3]; Peters, Thomas B. ^[3]; Geeting, Mark W ^[4]

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1. ORNL
2. Argonne National Laboratory (ANL)
3. Savannah River National Laboratory (SRNL)
4. Savannah River Remediation Company

This paper describes the chemical performance of the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) process in its current state of development for removal of cesium from the alkaline high-level tank wastes at the Savannah River Site (SRS) in the US Department of Energy (USDOE) complex. Overall, motivation for seeking a major enhancement in performance for the currently deployed CSSX process stems from needs for accelerating the cleanup schedule and reducing the cost of salt-waste disposition. The primary target of the NG-CSSX development campaign in the past year has been to formulate a solvent system and to design a corresponding flowsheet that boosts the performance of the SRS Modular CSSX Unit (MCU) from a current minimum decontamination factor of 12 to 40,000. The chemical approach entails use of a more soluble calixarene-crown ether, called MaxCalix, allowing the attainment of much higher cesium distribution ratios (DCs) on extraction. Concurrently decreasing the Cs-7SB modifier concentration is anticipated to promote better hydraulics. A new stripping chemistry has been devised using a vitrification-friendly aqueous boric acid strip solution and a guanidine suppressor in the solvent, resulting in sharply decreased DCs on stripping. Results are reported herein on solvent phase behavior and batch Cs distribution for waste simulants and real waste together with a preliminary flowsheet applicable for implementation in the MCU. The new solvent will enable MCU to process a much wider range of salt feeds and thereby extend its service lifetime beyond its design life of three years. Other potential benefits of NG-CSSX include increased throughput of the SRS Salt Waste Processing Facility (SWPF), currently under construction, and an alternative modular near-tank application at Hanford.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: EM USDOE - Environmental Restoration and Waste Management (EM)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1024251
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BORIC ACID
CESIUM
CHEMISTRY
CONSTRUCTION
DECONTAMINATION
FLOWSHEETS
GUANIDINES
HYDRAULICS
IMPLEMENTATION
LIFETIME
Nuclear waste treatment
PERFORMANCE
REMOVAL
SAVANNAH RIVER PLANT
SOLVENT EXTRACTION
SOLVENTS
TANKS
TARGETS
WASTE MANAGEMENT
WASTE PROCESSING
calixarene
cesium
flowsheet
tank waste