[en] At the Belgian Nuclear Research Centre SCK-CEN, several experiments concerning safety aspects of Liquid Metal Fast Breeder reactors were carried out. During these experiments, an important amount of sodium containing waste was produced. In view of the treatment of this waste, a literature study was performed and third parties were contacted to find a solution. This document summarizes the results of this study. The sodium waste has been characterized by a theoretical study and by radiological measurements. The waste consists mainly of metallic sodium contaminated with corrosion activation products, fission products and even fuel particles. The sodium might also be contaminated with oxidation and reduction products like Na₂O and NaH. The most important contaminant is ¹³⁷Cs. Several third parties, with experience in treating sodium, were contacted and they proposed a treatment of the sodium based on its reaction with water or alcohol. From a safety point of view, these reactions are not satisfactory because they are all exothermic and lead to flammable products or even make use of flammable reactants. Therefore, all the parties foresee extensive and expensive studies prior to the treatment. The urgent nature of the issues together with the important safety aspects were the incentives for the Research and Development group of the Radioactive Waste and Cleanup to look for alternatives. For this purpose, a research programme has been started with the aim to define, test, demonstrate and finally apply a safe process for the treatment of contaminated sodium by oxidation on a fluidized bed followed by vitrification. The collected information confirms that the oxidation of sodium vapour can be carried out safely, leading to the formation of sodium peroxide and oxide