Fig. 9.

Comparison of LLNL’s (a) standard operating procedure for Pa separations on pure U metals [29] and (b) the modified procedure for depleted U–Nb alloys. LLNL’s standard operating procedure for Pa separations involves two columns of AG 1-X8, followed by one silica gel column. For depleted U–Nb alloys, LLNL added two additional AG 1-X8 columns to the beginning of the standard operating procedure. In the schematic, the taller columns represent Environmental Express columns (5.5 mL volume) and shorter columns represent Bio-Rad Poly-Prep columns (2 mL volume). In the eluates, colors represent the elution of Th (green) and Pa (red), with changing opacity representing sequential improvements to the purity of each element (i.e., dark red represents a more purified Pa solution). To highlight the differences between the two procedures, certain steps such as resin cleaning, column conditioning, acid washes, and the application of H₃BO₃ as a fluoride scavenger have been abridged or omitted from this schematic; please refer to Treinen et al. (2018) [29] and the Supplementary Materials of this article for complete descriptions of the standard and modified procedures