Selective separation of radium and actinium from bulk thorium target material on strong acid cation exchange resin from sulfate media

This work presents a complete scheme for the selective separation of actinium and radium isotopes from bulk 232Th target material, in a process that may be applied in a separation scheme for the production of 225Ac by proton spallation on thorium. Thorium metal is dissolved in sulfuric acid with small amounts of HF. Actinium and radium are retained on cation exchange resin from the sulfate medium, while neutral and anionic thorium sulfate complexes are rejected. Following rinsing steps to remove residual thorium, actinium and radium are recovered from the cation exchange resin using 5 M HNO3. Further separations of actinium via extraction chromatography with UTEVA and DGA resins yield actinium in >92% yield, while providing additional decontamination from thorium and other spallation byproducts. The radium fraction can be further processed following ingrowth of 225Ac from 225Ra to produce additional 225Ac free from any potential 227Ac impurity.