Development of a Safe Technology for the Treatment of Sodium Waste: Early Experience

SCK-CEN carried out several experiments involving molten sodium as coolant, mainly to qualify fuel elements for fast breeder reactors. At the end of the campaigns the fuel bundles were provisionally stored, lacking an effective process for the safe treatment of contaminated sodium. Years ago SCK started to look for an efficient and safe technology for this waste resulting in a waste form which is ready for further conditioning. Direct controlled oxidation with water or with an alcohol was considered to be inadequate for our purposes mostly for safety reasons and because of possible complications during the further immobilization of the produced waste. Recently we started the development of a simple and safe batch process to meet safety requirements and which would render the sodium into a non-reactive form, compatible with further conditioning of the waste into an acceptable form.During this process no hydrogen is formed, while the turbulent conditions guarantee a complete conversion of the metal and excellent heat transfer capabilities, eliminating explosion risks. After initial testing of the process on lab scale, a small pilot installation was constructed to demonstrate the process with non-active sodium in batches of about 5 kg Na.