LOW-RADIOACTIVITY-LEVEL WASTE TREATMENT. PART I. LABORATORY DEVELOPMENT OF A SCAVENGING-PRECIPITATION ION-EXCHANGE PROCESS FOR DECONTAMINATION OF PROCESS WATER WASTES

A scavenging-precipitation ion-exchange process using phenolic resins was developed to decontaminate lowradioactivity-level process water waste prior to discharge to the environment. In laboratory and small engineeringscale tests, greater than 99.9% of the cesium and strontium, the principal biological hazards were removed from ORNL low-level waste, and the total activity level was lowered to less than the maximum permissible concentration recommended for populations in the neighborhood of atomic energy installations. The water was treated by a scavenging-precipitation with sodium hydroxide, pH 11.7, and ferrous sulfate, copperas-5 ppm Fe, to remove suspended solids and soluble hardness, clarified, and then passed through a carboxylic-phenolic ion-exchange resin to sorb the remaining radionuclides. After passage of 1,500 to 2,000 resin-bed volumes, the resin was eluted with 10 volumes of 0.5 M HNO/sub 3/. Sodium carbonate can be added in the precipitation step to aid the quantitative precipitation of calcium for wastes that contain small amounts of phosphates, or alternatively, an extra ion-exchange column of carboxylic resin can be used to remove calcium and thus conserve the capacity of the phenolic resin for cesium and strontium. Three kinds of studies were made: batch laboratory-scale studies, continuous nonradioactive runs at 15 liters/hr, and runs with radioactive waste at 60 liters/ hr. These studies led to a pilot-plant demonstration of the process. The process is similar to that reported in ORNL-3036, which describes the use of a sulfonic-phenolic resin and a 5 M HCl regenerant. (auth