Methodology for the characterization of low-level radioactive waste at the Oak Ridge National Laboratory

Low-level liquid radioactive waste originates from a number of different source facilities at the Oak Ridge National Laboratory (ORNL). Sources include reactors, radioactive fuel and target processing facilities, decontamination operations, hot cells, and analytical laboratories. Waste generated at these source facilities are collected in storage tanks distributed throughout ORNL. Many of the source facilities generate acidic nitrate wastes which are neutralized with sodium hydroxide in the collection storage tanks. The stored waste is essentially a high-pH, sodium nitrate, salt solution with smaller concentration of potassium, calcium, and magnesium cations, and sulfate chloride, fluoride, and phosphate cations. The principle radionuclides are strontium-90, cesium-137 and cobalt-60. Data on the chemical and physical form of the waste are needed to evaluate the practicality of various processing options and to analyze the resulting waste forms. Data on radiochemical concentrations are needed to predict dose rates and shielding requirements around processing equipment and waste packages and to provide a data base for leach tests and other immobilization requirements. This paper describes chemical and physical measurement techniques that have been used to characterize low-level waste at ORNL