Recent Sodium Technology Development for the Decommissioning of the Rapsodie and Superphénix Reactors and the Management of Sodium Wastes

The Commissariat à lʹEnergie Atomique (CEA) has recently developed and/or conducted experiments on several processes in support of the decommissioning of two French liquid-metal fast reactors (LMFRs), Rapsodie and Superphénix, as well as on the treatment of CEA sodium wastes. CEA has demonstrated that it is possible to define appropriate and efficient processes to meet the different situations encountered in decommissioning LMFRs. Mechanical techniques derived from standard technologies have been successfully applied to fast reactor decommissioning to complete primary vessel draining from sodium. In addition, specific chemical processes have been developed to deal safely with metallic sodium reactivity. Sodium-contaminated equipment has been successfully cleaned by reacting sodium with water mist in an atmosphere with carbon dioxide to form inert sodium carbonate. Bulk sodium has been successfully converted into aqueous caustic soda by injection of liquid-metallic sodium into sodium hydroxide solution. Several processes were also defined to deal with specific sodium wastes. In all cases the principle is based on a sodium/water chemical reaction where the released hydrogen and heat are controlled. With the development of a wide variety of processes, all steps in the decommissioning of LMFRs are assumed to be now properly mastered