Fig. 11-2 Four-group Partitioning Process Under Development

Fig. 11-3 Equipment Installed in NUCEF for the Partitioning Test

High-level waste (HLW) generated from nuclear fuel reprocessing contains transuranic elements (TRU), most of which have half-lives longer than one million years; Sr and Cs, which are the main heat-generating and radiation- emitting elements; and Tc and platinum group metals (PGM), which are valuable elements. Partitioning is the separation process for these elements based on their radiological toxicity and chemical properties. This enables the transmutation of TRU and the utilization of some valuable elements or isotopes. JAERI has been developing the Four-group Partitioning Process (Fig.11-2). In the TRU separation step, diisodecylphosphoric acid (DIDPA) is used as an extractant. It provides a very high recovery of TRU. An experiment with actual HLW resulted in 99.99% recovery of Am. Np in simulated HLW was recovered with a yield of 99.95%. DIDPA can also be applied to the separation of Am and Cm from rare earths (RE). This is one of the most important applications for DIDPA. Equipment for a test of the partitioning process with an actual HLW (Fig.11-3) has just been installed in a hot cell in NUCEF, a new facility at JAERI. A study from a chemical engineering point of view will be performed to provide the knowledge needed to design and operate an actual partitioning plant.

Reference M. Kubota et al., Development of a Partitioning Process for the Management of High-Level Waste, Proc. of Intern. Conf. and Technol. Exposition on Future Nuclear Systems: Emerging Fuel Cycles and Waste Disposal Options-Global '93, Sep. 12-17, Seattle, WA. USA. 588.

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