Vitrification of mixed waste from uranium processing operations

摘要

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 such 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.