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The possibility of concentrating liquid radwastes by evaporation from the surface of porous plates is examined. It is shown by means of tests of a laboratory setup and an experimental stand that liquid radwastes can be concentrated to salt content 319 g/liter at a temperature far below the evaporation temperature of water and with specific energy consumption 20 times lower that the specific heat of vaporization of water. The results of the tests of the experimental setup with capacity up to 43 kg/h with respect to the evaporated water are described; this setup has been incorporated in the EKO mobile modular water purification complex used at the MosNPO Radon for reprocessing radioactive water from various organizations.When liquid radwastes are purified by, for example, evaporation, membrane separation followed by regeneration, and other methods, secondary wastes which are often represented by liquid concentrates are always formed. It is obvious that their volume must be decreased to a minimum, since the costs of concentrating the wastes and then storing them for a long time are very high. Evaporation of water (thermal or natural) [1,2] or membrane concentration of water impurities [2, 3] are ordinarily used for this purpose.The main drawbacks of thermal evaporation are high complexity and high metal content of the equipment, high specific energy consumption, temperature close to the boiling point of water, and often elevated pressure in the channels of the evaporation apparatus. Natural evaporation requires dry air and large-size equipment (water-cooling towers, ponds, or evaporation vessel). Membrane methods likewise are not devoid of substantial drawbacks. The pressure in reverseosmosis apparatus reaches 8 MPa, and the salt content of the concentrates is rarely greater than 50 g/liter. In concentration by electro-osmosis, the salt content of the brine can reach 250 g/liter but in such apparatus hydrogen or corrosive gases are often the products of electrode reactions. Membrane distillation [4] makes it possible to attain a concentrate with salt content 500 g/liter, but if surfactants are present in the solution than this method rapidly becomes ineffective. The process is characterized by low specific capacity and overgrowth in the capillaries during the concentration process.The objective of the present work was to develop a technology for concentrating liquid radioactive wastes at a temperature much lower than the boiling point of water and a mobile facility for implementing this process. Building and testing the facility were also part of the problem considered in this work.The crux of the technology is that the liquid wastes are fed from above into a press-filter type evaporation chamber assembled from porous, channeled, hydrophyllic plates and air with relative moisture content 100% is passed through the channels formed in the plates (Fig. 1). The radioactive solution flows down along the plates under gravity. In the process, water is continually removed from the solution by evaporation and therefore the r...

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