Approximately 4.3 kg of slurry from Hanford Tank AZ- 101 were evaluated by the pretreatment processes of cross-flow filtration, washing, caustic leaching, and rinsing. The filterability was measured with a 0.1- mum sintered metal filter using a single-element, cross-flow filtration system. During testing, the permeate flux and slurry axial velocity, pressure, and temperature were monitored every 10min. The slurry temperature was maintained at 25degreesC +/- 5degreesC, except during the elevated-temperature leaching step. The test results show that cross-flow filtration provides excellent separation of solids and liquids, as evidenced by the permeate flux and the measured activity of nearly insoluble Am-241. The average permeate flux measured was higher than the Waste Treatment Plant target of 0.014gpm/ft(2), and the average decontamination factor for Am-241 was 985,000 during testing.