Optimization of flow sheet for scrubbing of ruthenium in reprocessing of fast reactor spent fuel

Ruthenium and zirconium are identified as two most troublesome fission products that would determine the extraction flow sheet for the reprocessing of short cooled fast reactor fuels. Hence presence of these two fission products together in a feed solution complicates process as the solvent chemistry is entirely different at a given nitric acid concentration. To establish a sound flow sheet, it is necessary to determine the distribution ratios accurately. This paper describes effect of concentration of nitric acid in feed and uranium loading in organic solvent on distribution ratio of Ru. The solvent extraction chemistry of ruthenium is very complex due to the presence of different nitro, nitrate, nitrosyl species of ruthenium in the dissolver solution. These species have different extractability. As the determination of these complexes is very difficult, it is decided to spike the ruthenium with the non radioactive ruthenium and generate the equilibrium data. As ruthenium sample is taken from the actual dissolver solution, this will represent the behaviour of ruthenium under plant condition