Canyon Solvent Cleaning with Activated Alumina

Solvent extraction processes are used to recover usable nuclear materials from unwanted fission products at the Savannah River Plant. During use, the tri-n-butyl phosphate in an n-paraffm hydrocarbon solvent is degraded due to hydrolysis and radiolysis, forming materials that influence product losses, product decontamination, and separation efficiencies. The solvent is recycled after cleaning with a sodium carbonate solution. Savannah River Laboratory work has shown that carbonate washing does not remove more solvent-soluble binding ligands (formed by solvent degradation), which extract fission products into the solvent. Activated alumina treatment of carbonate-washed solvent removes binding ligands and significantly improves recycled solvent performance. A laboratory-developed, side-stream-activated alumina process was scaled up to clean 16500 gal of first-cycle solvent. The improved solvent fission product rejection returned the Savannah River Plant Canyon process to normal productivity and reduced process salt waste by increasing the solvent wash solution use-life.