Simulation studies to develop an alternative off gas scrubbing method for removal of nitrogen oxides during dissolution of spent fuel

Uranium dioxide (UO₂), mixed uranium plutonium carbide (MC) and mixed uranium plutonium dioxide (MOx, (U,Pu)O₂) are important nuclear reactor fuels. During the reprocessing of these irradiated fuels, they are dissolved in nitric acid to produce a dissolver solution, which is suitable for the solvent extraction chemical separation process. Due to the chemical conditions that prevail in a typical PUREX process, only NO and NO₂ gases gets generated during dissolution. The composition of these NOX gases depends on the initial concentration of the nitric acid. Nitrogen dioxide (NO₂/N₂O₄) is a brown gas that poses health hazards at levels above 15 ppm. Additionally, the presence of NO₂ in the stack off gas creates a visible plume. These are issues of serious concern to any reprocessing plant. Hence, dissolver off gases has to be treated to scrub or absorb NOx gases via dissolver off gas treatment, before releasing into the environment. The dissolver off gas passes through reflux condenser, three scrubbers in series with a demister. The gas outlet from demister is connected to the suction of booster ejector and discharge of the ejector is connected to VOG system before releasing to stack