The US Department of Energy (DOE) has established the Tank Waste Remediation System (TWRS) to safely manage an dispose of the Hanford Site tank waste. Pretreatment is one of the major program elements of the TWRS. The scope of the TWRS Tank Waste Pretreatment Program is to treat tank waste to separate it into high- and low-level waste fractions and to provide additional treatment as required to feed low-level waste fractions and to provide additional treatment as required to feed low-level and high-level waste immobilization processes. The Pretreatment Program activities include technology development, design, fabrication, construction, and operation of facilities to support the pretreatment of radioactive mixed waste retrieved from 28 large underground double-shell tanks and 149 single-shell tanks.

The US Department of Energy's (DOE) Hanford Site, located in southeastern Washington State, has the most diverse and largest amount of radioactive tank waste in the US. A Tank Waste Remediation System (TWRS) Program was established in 1991 to safely store, treat, and dispose of those wastes. This paper describes the technical challenge in conducting the TWRS Program that will take more than 30 years and cost tens of billions of dollars to complete.

The US Department of Energy's Hanford Site, located in southeastern Washington State, has the most diverse and largest amount of radioactive tank the United States. High-level radioactive waste has been stored in large underground tanks since 1944. Approximately 230,000 m3 (61 Mgal) of caustic liquids, slurries, saltcakes, and sludges have accumulated in 177 tanks. In addition, significant amounts of 9°S and 137Cs were removed from the tank waste, converted to salts, doubly encapsulated in metal containers, and stored in water basins. A Tank Waste Remediation System Program was established by the US DOE Energy in 1991 to safely manage and immobilize these wastes for permanent disposal of the high-level waste fraction in a geologic repository. The technical strategy to manage and dispose of these wastes has been revised and successfully negotiated with the regulatory agencies.

The U.S. Department of Energy's Hanford Site, located in southeastern Washington State, has the most diverse and largest amount of highly radioactive waste in the United States. High-level radioactive waste has been stored in large underground tanks since 1944. Approximately 230,000 m3 (61 Mgal) of caustic liquids, slurries, saltcakes, and sludges have 137Cs accumulated in 177 tanks. In addition, significant amounts of 9°Sr and were removed from the tank waste, converted to salts, doubly encapsulated in metal containers., and stored in water basins. A Tank Waste Remediation System Program was established by the U.S. Department of Energy in 1991 to safely manage and immobilize these wastes in anticipation of permanent disposal of the high-level waste fraction in a geologic repository. Since 1991, progress has been made resolving waste tank safety issues, upgrading Tank Farm facilities and operations, and developing a new strategy for retrieving, treating, and immobilizing the waste for disposal.