Radiochemical separation and purification of 144Ce from Purex high-level waste

A solvent extraction technique has been developed for the radiochemical separation and purification of Ce-144 from Purex high-level waste (HLW). The feed solution initially was in contact with granulated ammonium molybdophosphate for the selective removal of cesium to reduce the gamma dose during the subsequent process. In the next step, uranium and plutonium were removed quantitatively by using 20% 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate (KSM-17) in dodecane. The trivalent cerium present in the cesium-, uranium-, and plutonium-depleted raffinate was oxidized to its tetravalent state by using K2Cr2O7 and was extracted into KSM-17. The loaded cerium from the organic phase was stripped with 0.5 M nitric acid. Final decontamination from trace impurities such as Ru-106 and Sb-125 could be achieved by an additional cerium-extraction step with KSM-17 at pH 2, followed by its stripping with 0.5 M HNO3. About 10 mCi of cerium was separated from Purex HLW by using this technique. This method is amenable for automation and scale up.