Retrieval and purification of an aged 231Pa source from its decay daughters

Abstract

Abstract The retrieval and purification of a macroscopic aged sample of protactinium-231 is described. The 231Pa was separated from its decay daughters using a precipitation based method. The method exploits the hydrolytic behavior and insolubility of protactinium rather than attempting to avoid it by way of concentrated hydrofluoric and sulfuric acids, which have been shown to vitiate separations using ion-exchange and solvent extraction based methods. Based on alpha spectrometry the source was previously separated in 1959–1960, consistent with the Harwell Pa separations program. The method described here achieved 98% recovery of the 231Pa with a final alpha-radiopurity of 93.75% in contrast to the 20.25% radiopurity of the starting material.