Plutonium and Neptunium Conversion Using Modified Direct Denitration

Plutonium and Neptunium Conversion Using Modified Direct Denitration
L. K. Felker, R. J. Vedder, R. R. Brunson, and E. D. Collins

Nuclear Science and Technology Division

Oak Ridge National Laboratory

P. O. Box 2008

Oak Ridge, TN 37831-6384
ABSTRACT
The processing of spent nuclear fuel through the various stages of separations yields a number of product and waste streams, typically in nitric acid solutions that require conversion to a solid form for recycle, storage, or disposal. One of the product streams of interest is the separated plutonium and neptunium product, which if successfully converted to an oxide product, could be blended with uranium oxide for recycle and further transmutation as a mixed-oxide fuel. Another option would be the coconversion of the uranium/plutonium/neptunium nitrate steam to an oxide. The desire is for the conversion process to generate an oxide product with the proper ceramic properties (particle size, density, surface area) for blending and fuel fabrication without further processing steps. While direct denitration yields an oxide product, the ceramic properties of the oxide produced are poor and subsequent processing steps would be necessary to obtain the desired properties for fuel fabrication. The modified direct denitration process was developed mainly for uranyl nitrate conversion and has been demonstrated on a pilot scale to produce oxides having the desired ceramic properties. The purpose of this study was to investigate the use of the modified direct denitration process to convert a separated plutonium/neptunium stream to an oxide product with favorable ceramic properties for blending and mixed-oxide fuel fabrication. A laboratory-scale unit was installed in an alpha-containment glove box for testing the modified direct denitration process on a number of possible processing streams. Initial testing with cerium nitrate solutions to establish operating parameters, and initial results on the conversion of purified plutonium/neptunium solutions and uranium/plutonium/neptunium solutions from irradiated fuel processing will be presented.