Significant Results in Low-level Waste Treattvents at ORNL

Abstract

Operating experience with the 500,000 gal/day waste treatment plant at Oak Ridge National Laboratory has demonstrated that plant efficiency exceeds the design specifications of 50% removal of gross radionuclides. An average of 85-- 90% of the Sr/sup 90/ and Cs/sup 137/ are removed. However, the full potential of the treatment plant can be realized only by modifying the process or by adding to the facility. A number of laboratory experiments were performed to investigate the effect of priraary coagulants, of coagulant aids, and the use of natural minerals, on the removal oi strontium and cesium. By optimizing the comrbination of lime, soda ash, and clay, removal of strontium and cesiunr was increased to 96 and 92%, respectively. Both supplemental phosphate addition to lime-soda softening and aluminum phosphate coagulation removed 98% of the strontium. Coagulant acids reduced the tarbidity in treated waste and resulted in improved efficiency. Vermiculite (grade BO-4), one of the most promising of the minerals investigated, exhibited distribution coefficients for strontium and cesium in excess of 5000 for a solution typical of the effluent from the waste treatment plant. Process changes and possible addition to the plant were evaluated by direct application to the operating plant or bymore » pilotscale tests. (auth)« less