The Treatment Technology of Radioactive Sodium in the Frame of Fast Reactors Decommissioning

A number of sodium fast reactors around the world have been shut down permanently, most of which use sodium as coolant in liquid form. Owing to the extremely high chemical reactivity of sodium, radioactive sodium waste arising during decommissioning reactors requires unique treatment technologies. The paper introduces various technologies about treatment of radioactive sodium, as follows: drained bulk radioactive sodium treatment, polluted radioactive sodium treatment. By comparing the discussed technologies in the following aspect of advantages, disadvantages, limitations, industry experiences, hazards, and final waste products, the paper concludes with recommendations about the preferential treatment technology of radioactive sodium.

35 Years of Operating Experience of PHENIX NPP Sodium Cooled Fast Reactor

Design features: Reactor core. The reactor block is of an integrated design (pool) except for a few auxiliary circuits. The entire primary sodium system, containing 800 tons of radioactive sodium, is enclosed in the main reactor vessel, which is 11.8 m in diameter (Fig. 1).

ATENA: Project of Storage and Disposal Plant for Radioactive Sodium Wastes

CEA, in the framework of its research and development activities in support of Liquid Metal Fast Reactors (LMFR), has developed experimental or demonstration plants, now at end of life, which are potential or existing sources of wastes containing sodium. The sodium waste management of CEA forecasts the disposal of the sodium contained in these wastes by water and soda processes, with existing means for the non radioactive sodium, and with a specific plant, to be built, for radioactive sodium. The project ATENA (Atelier de Traitement et d’Entreposage du Na Actif, Workshop for Processing and Storage of radioactive Na) answers to this need of central processing plant for radioactive sodium wastes generated by CEA. It concerns only the wastes: • containing radioactive sodium, • transportable, • which could not be processed by Phénix and Superphénix facilities for treatment of large primary or secondary sodium volumes, presently in project. FRAMATOME ANP direction NOVATOME, French LMFR engineering, is chosen as project manager for ATENA. ATENA will be a new plant with: • a storage module, able to be a central storage for wastes held at present by several of CEA’s plants, • a process module: disposal of sodium with several processes, • a packaging module for wastes resulting from these treatments: packaging of soda and metallic pieces in solid ultimate wastes. The three chosen disposal processes are existing and are validated. They apply to several wastes to be processed according to the activity of the contained sodium, to the capability of the sodium to be liquified or separated from its container: • continuous and controlled injection of liquid sodium in soda (NOAH process), • treatment of solid sodium aggregated with metallic pieces, by controlled and continuous spray of water (Enceinte de Lavage en Actif, Active Washing Enclosure), • treatment of solid and very radioactive sodium, aggregated or not with metallic pieces, by non-controlled immersion in water (Autoclave). We present the general concepts of ATENA plant, the process options and safety principles as chosen after the basic design phase.

Problems of Radioactive Sodium Removal and Disposal From Decommissioning LMFR Equipment

ABSTRACTPreparing for safe disposal of the LMFR primary circuit equipment and sodium reprocessing for storage and burial with minimum volume of radioactive wastes resulted in testing of radionuclide sorption trapping, distillation and rinsing with water under vacuum used for safe sodium removal and decontamination of equipment.