Reprocessing of simulated voloxidized uranium–oxide SNF in the CARBEX process

Abstract

The concept of a new method, the CARBEX (CARBonate EXtraction) process, was proposed for reprocessing of spent uranium oxide fuel. The proposed process is based on use of water solutions of Na2CO3 or (NH4)2CO3 and solvent extraction (SE) by the quaternary ammonium compounds for selective recovery and purification of U from the fission products (FPs). Applying of SE allows to reach high degree of purification of U from FPs. Carrying out the processes in poorly aggressive alkaline carbonate media leads to increasing safety of SNF's reprocessing and better selectivity of separation of lanthanides and actinides. Moreover carbonate reprocessing media allows to carry out a recycling and regeneration of reagents. We have been done laboratory scale experiments on the extraction components of simulated voloxidated spent fuel in the solutions of NaOH or Na2CO3–H2O2 and recovery of U from carbonate solutions by SE method using carbonate of methyltrioctylammonium in toluene. It was shown that the purification factors of U from impurities of simulated FPs reached values 103–105. The received results support our opinion that CARBEX after the further development can become more safe, simple and profitable method of spent fuel reprocessing. Keywords: Simulated spent nuclear fuel, Simulated fission products, Oxidative dissolution, Solvent extraction, Quaternary ammonium compounds