Wastewater Triad Project: Final Summary Report

Abstract

The U.S. Department of Energy (DOE) facilities have performed nuclear energy research and radiochemical production since the early 1940s. Currently, millions of gallons of legacy radioactive liquid and sludge wastes are contained in over 300 large underground storage tanks, located primarily at Hanford, the Savannah River Site (SRS), Idaho National Engineering and Environmental Laboratory (INEEL), and Oak Ridge National Laboratory (ORNL). Plans for tank waste retrieval, treatment, and immobilization are being developed and implemented throughout the DOE complex In order to meet regulatory requirements for remediation of underground storage tanks, ORNL has developed an integrated approach to the management of its waste that has applications across the DOE complex. The integrated approach consolidates plans for remediation of inactive tanks; upgrade of the active waste collection, storage, and treatment systems; and treatment of transuranic (TRU) tank waste for disposal. Important elements of this integrated approach to tank waste management include waste retrieval of sludges from tanks, conditioning and transport of retrieved waste to active storage tanks or treatment facilities, solid/liquid separations for supernatant recycle and/or waste treatment, removal of cesium from the supernatant, volume reduction of the supernatant, and solidification of sludges and supernatant for disposal. Each unit operation of the flowsheet is interconnected and impacts the overall efficiency of the entire flowsheet. ORNL has implemented innovative but proven technologies for each of the major unit operations to accelerate clean-up. ORNL used the integrated plan to determine where developing technologies were required to create an optimized flowsheet to (1) accelerate clean-out and remediation of underground storage tanks; (2) provide significant cost avoidance and schedule reductions; (3) consolidate wastes for private-sector immobilization; (4) facilitate regulatory compliance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), Resource Conservation and Recovery Act (RCRA), and Land Disposal Restrictions (LDR) regulations; and (5) deploy state-of-the art technologies that have applications across the DOE complex. Partnerships were developed with DOE technology development agencies, private-sector companies, and other DOE sites to accomplish implementation of these technologies.