[en] When high-burnup LWR fuels are reprocessed, fission products cause solids formation during solvent extraction. Several methods for clarifying LWR dissolver solutions have been evaluated. Chemical treatment as well as centrifugation will be necessary to provide clarified feed for solvent extraction. Addition of an organic flocculant is the most promising method. The best flocculant tested, Primafloc C-3, clarified dissolver solutions noticeably even at flocculant concentrations of only 0.2 ppM. Unlike observed behavior of some other flocculants, even at the highest concentration tested (8300 ppM) no redispersion or flotation of solids were observed. The standard Purex MnO₂ treatment clarified test solutions adequately, but significantly added to the solids content of the aqueous wastes. No fission product decontamination was obtained and there was evidence of dissolution of fission product PuO₂ during MnO₂ precipitation