Використання технологій опріснення морської води для попереднього упарювання рідких радіоактивних відходів

Abstract

Processing of liquid radioactive waste (LRW) includes evaporation followed by vitrification. Reducing the energy consumption of evaporation of LRW is an urgent task. In the article, an attention is paid to the fact that similar technical and economic problems are solved with the desalination of seawater. It is proposed to use well-developed seawater desalination technologies for preliminary evaporation of LRW. For a detailed analysis, desalination technology with mechanical vapor compression (MVC) was selected. This technology is energy-saving because it implements the heat pump principle. MVC technology is highly efficient, simple, and does not lead to the generation of secondary radioactive waste. A mathematical model of a single-stage desalination plant with MVC has been developed, taking into account that the thermodynamic cycle of this process is open. Since there are no data on the physical properties of LRW in the literature, the properties of sea water were used. The design and operational parameters were optimized in order to reduce the cost of 1 m3 of evaporated water. It has been established that the main design parameters affecting the cost of evaporated water are the degree of vapor compression in the compressor and the heat exchange surface area of the evaporatorcondenser. The influence of these parameters on capital and operating costs is shown. The optimal combinations of these parameters are determined. To ensure the optimal operating mode of the installation, it is necessary to maintain the optimum salt content of boiling brine, which is determined by the rate of consumption of the source water. The optimal values of these parameters are calculated in a wide range of salt content of the source water. It is shown that, at low salinity of the initial LRW, evaporation is advisable to be carried out in a multi-stage installation. As a result of the calculations, it was found that the specific cost of evaporation of liquid radioactive waste with an initial salt concentration of 10% to a salt content of 20% using the desalination technology with mechanical vapor compression is 0.843 USD/m3.