Cold War plutonium production activities created complex wastes. Vitrifying the waste for final storage is complicated by aluminum from nuclear fuel reprocessing. Knowing how aluminum particles behave in highly radioactive liquids is vital. Here, research focused on humid particles suggest that the particles’ bulk properties do not change substantially upon radiolysis. Gamma radiolysis led to the formation of hydrogen from the adsorbed water with the oxygen atoms remaining on the surface or intercalating into the bulk.