On possibility of the murataite fusion temperature lowering for radioactive waste immobilisation

Abstract

The problem of radioactive waste management is extremely important for the nuclear energy development. The global strategy for safe handling of all types of radioactive waste consists is aimed at reducing volumes by concentrating and entering into radionuclides inside stable solid matrices. The most dangerous components of high-level radioactive waste are supposed to be immobilized in mineral-like matrices with their further safe disposal in geological formations. The solution can be glass-ceramic matrix materials, in particular, obtained by direct melting: resistant as crystal matrices and a simple method of preparation - like glass. The most promising from the point of view of the process of obtaining and the range of included nuclides is murataite. Ceramics can be obtained by melting the initial composition of powders with HLW components at a temperature of 1350°C. The authors of this work previously showed the fundamental independence of the quality of the ceramics obtained from the exposure time in a liquid state. In this work, the possibility of obtaining fused murataite at a low synthesis temperature with the introduction of fluxing agents was experimentally shown. The decrease in temperature does not prevent the formation of murataite under the condition of the presence of a liquid phase. A significant influence of the quality of the preparation of powder and tablets on the resulting structure of ceramics has been established. Also demonstrated is the possibility of obtaining murataite without the addition of a fluxing agent with the introduction of fluorides MnF2 and FeF3 into the initial mixture of murataite instead of corresponding oxides.