A strategy for resolving high-priority Hanford Site radioactive waste storage tank safety issues

High-activity radioactive waste has been stored in large underground storage tanks at the US Department of Energy's (DOE) Hanford Site in Eastern Washington State since 1944. Since then, more than 227,000 m3 (60 Mgal) of waste have been accumulated in 177 tanks. These caustic wastes consist of many different chemicals. The waste forms include liquids, slurries, salt cakes, and sludges. A number of safety issues have been raised about these wastes, and resolution of these issues is a top priority of DOE. A Waste Tank Safety Program has been established to resolve these high-priority safety issues. This paper will deal with three of these issues. The issues described are the release of flammable vapors from single- and double-shell tanks, the existence of organic chemicals, and/or ferrocyanide ion-containing fuel-rich mixtures of nitrate and nitrite salts in single-shell tanks