PNNL

Abstract

Multiple tests of a co-decontamination (CoDCon) tributyl phosphate (TBP) based solvent extraction flowsheet are being performed to determine the uncertainties associated with maintaining a target U/Pu ratio in the Pu-containing product. The first two flowsheet tests used simple dissolved fuel simulants containing only U and Pu, but increasingly more complex simulants will but used in subsequent tests, with the ultimate goal of performing tests with irradiated fuel. The flowsheet is designed so as not to create a purified Pu stream, but rather a mixture of U and Pu with a U/Pu mass ratio of 7/3. Uranium and Pu are first co-extracted into the TBP solvent, and then U(IV) is used to strip the Pu from the loaded solvent. A fresh TBP solvent stream is introduced at the same stage the Pu-containing aqueous stream exits. The flowrate of the fresh TBP solvent stream is adjusted so that sufficient U bleeds over into the Pu product to produce the desired U/Pu ratio. The system is monitored in real time using optical spectroscopy, which allows for control of the U/Pu ratio through adjustment of the fresh TBP solvent flowrate. This paper will describe the results of the first two CoDCon flowsheet tests.