A reverse osmosis process has been found to be effective for the separation of radiocontaminants from ammonium diuranate effluents in a uranium metal plant. Pilot-plant-scale experiments were conducted using cellulosic membranes in a plate module system and actual plant effluents containing more than about 40,000. ppm of ammonium and nitrate species and having radiocontaminants corresponding to specific activities of about 10(-3) Ci/m3 beta/gamma emitters. The results indicated that more than 95% by volume of the treated effluents were within disposal limits, while the remaining contained the concentrate, which can be treated for possible containment.