New approach to the nuclear fuel reprocessing in non-acidic aqueous solutions

A new nuclear fuel reprocessing method based on the anodic dissolution of s pent fuels in aqueous alkaline solutions (Na2CO3-NaHCO3) has been proposed. Experiments of the anodic dissolution were performed by using a simulated spent fuel in a Na2CO3-NaHCO3 solution. Uranyl ions produced anodically wer e present in the solution as stable carbonato complexes, and at the same ti me, most of the simulated fission products (FP) were precipitated as hydrox o or carbonate compounds. Under this condition, Cs of an alkali metal group was dissolved in the solution and precipitated by adding sodium tetrapheny lborate. Uranyl ion was recovered as hydroxo compounds by adding NaOH to th e solution after removing precipitates of the simulated FP. In view of wast e disposal, Tc-99 having a long half-life should be removed. Precipitation behavior of Tc(VII) was examined by using Re(VII) as a simulant of Tc(VII). It was found that Re(VII) species are completely removed as a precipitate by adding tetraphenylphosphonium chloride. A large amount of Na used in the present method was recovered as NaHCO3 by blowing CO2 into alkaline soluti ons. As a result, it was clarified that the proposed method is fundamentall y possible as a new reprocessing method.