Development of a cobalt dicarbollide/polyethylene glycol solvent extraction process for separation of cesium and strontium to support advanced aqueous reprocessing

A chlorinated cobalt dicarbollide (CCD)/polyethylene glycol (PEG) based solvent extraction process is being developed for the separation of Cs and Sr from leached spent light water reactor (LWR) fuel as part of the Advanced Fuel Cycle Initiative (AFCI). The separation of Cs and Sr would significantly reduce the heat generation of spent nuclear fuel requiring geologic disposal. A solvent composition for this process has been verified, and the distribution coefficient acid dependency for Cs, Sr, Am, and Eu have been measured for the CCD/PEG solvent. Leached spent fuel simulant, traced with ¹³⁷Cs, ⁸⁵Sr, ²⁴¹Am, and ¹⁵⁴Eu, was used to perform batch contact flowsheet experiments for the extraction, scrub, and strip sections of the CCD/PEG process. Additionally, the effects of acetohydroxamic acid and its decomposition products, as well as the effects of the uranium extraction (UREX) process solvent, on the extraction of Cs and Sr with the CCD/PEG process were evaluated.