Vitrification of mixed waste from uranium processing operations

Three silos at the Fernald Environmental Management Project (FEMP) in Fernald, Ohio, contain residues from the processing of pitchblende ores. Silos 1 and 2, designated as K-65, contain the depleted ore, while Silo 3 contains calcined residue from processing solutions. Silos 1 and 2 also contain a bentonite clay cap that was added to the silos to reduce the radon emanation from the waste. Previously, the initial vitrification testing, conducted as a treatability study for the Remedial Investigation/Feasibility Study (RI/FS) being performed at the FEMP, demonstrated the feasibility of vitrifying the silo residues. Various combinations of the waste materials were successfully vitrified at 1350{degree}C with waste loadings ranging from 66 percent to 89 percent. Measured volume reductions ranged from 50 to 68 percent. All of the glasses tested ``non-hazardous`` by the Toxicity Characteristic Leachate Procedure (TCLP), and Product Consistency Test (PCT) testing showed the durability of the glasses to be equal to or better than typical high-level waste glasses. The radon emanation rate from the glass has been measured at less than 0.1 pCi/m{sup 2}/s, more than two orders of magnitude below the EPA limit of 20 pCi/m{sup 2}/s and about the same level as natural, ``non-radioactive`` building materials suchmore » as brick or concrete. This level represents a reduction in the emanation rate of more than 500,000 times from the non-vitrified residue. Although the initial treatability testing demonstrated the applicability of vitrification to these wastes, some areas requiring further work were identified.« less