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Abstract
A U-Pu co-crystallization reprocessing system is proposed for light water reactor fuels and its flowsheet study is carried out. This reprocessing system is based on experimental evidence indicating that Pu(VI) in a nitric acid solution is co-crystallized with uranyl nitrate, whereas it is not crystallized when uranyl nitrate is not present in the solution. The system consists of five steps: dissolution of spent fuel, Pu oxidation, U-Pu co-crystallization, re-dissolution of the crystals, and U re-crystallization. The proposed system does not require the use of organic solvents, resulting in a relative increase in safety and cost-effectiveness. The system requires recycling of the mother liquor from the U-Pu co-crystallization step to recover almost the entire amount of U and Pu at this step. The appropriate recycling ratio is determined, such that satisfactory decontamination is achieved. A consistent ratio of Pu to U in the mother liquor from the U re-crystallization is maintained by regulating the temperature, suggesting that the quality of the liquor, which can be a source of mixed oxide fuels, can be controlled despite differences in the composition of the spent fuel. The size of a plant utilizing the proposed system is estimated to be about 30% less than that of the PUREX system.
