Radiochemical Separation and Purification of ¹⁴⁴Ce from Purex High-Level Waste

ABSTRACT

A solvent extraction technique has been developed for the radiochemical separation and purification of ¹⁴⁴Ce 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 ¹⁰⁶Ru and ¹²⁵Sb 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.

Key Words::

• Radiochemical separation
• ¹⁴⁴Ce
• Purex HLW
• KSM-17