OPTIMIZATION OF MAGNETITE CARRIER PRECIPITATION PROCESS FOR PLUTONIUMWASTE REDUCTION

Transuranic (TRU) waste that is being generated at Argonne National La boratory has a TRU activity ranging from 10(2) to 10(7) nCi/g with a w ide variety of chemical compositions. Currently, the waste is stored i n highly acidic solutions that must be neutralized for intermediate st orage. A magnetite carrier precipitation process has been adapted to c oncentrate TRU isotopes in a noncorrosive solid phase. In this paper, we report the results of a series of laboratory tests done to optimize the process. The parameters we optimized included (1) magnetite conce ntration used to precipitate plutonium from solution, (2) formation of magnetite (in situ or ex situ), (3) processing pH, and (4) temperatur e and mixing time of the carrier precipitation. We also studied the ef fects of anions, cations, and complexing agents in the waste solutions on the carrier precipitation and the effect of magnetite solids loadi ng on the filtration equipment. An overview is given of the planned fu ll-scale process, which will be operated in a glovebox.