[en] H/D and ¹⁶O/¹⁸O isotope effects of water permeation with phase transition have been determined and their mechanism discussed. The special designed and build laboratory installation has been used for experiments. The isotope effects of permeation have been compared with isotope effects of vaporization. It has been found out that H/D effect of permeation exceeds the vapour pressure effect 1.5 times while the ¹⁶O/¹⁸O effect of permeation was 7 times as large as vapour pressure effect. The cascade installation for water enrichment in D₂O and H₂¹⁸O has been also designed. It has been proved that permeation method on hydrophobic membranes could be competitive for the other methods used for D₂O and H₂¹⁸O production on industrial scale

[en] Reverse osmosis is used were complete rejection of all dissolved compounds is required; it needs pre-treatment of the waste by microfiltration, ultrafiltration or other conventional technique to avoid the membrane blockage by colloids and suspensions. Recently the nanofiltration membranes are often used to separate monovalent ions from multivalent. Ultrafiltration apart of pre-treatment stage is used to separate colloids, which usually are formed by compounds of ⁵⁴Mn, ⁵⁵Fe. ⁶⁰Co and ¹²⁵Sb. Microfiltration found application for solid wastes dewatering before final disposal. A novel technology is membrane distillation proposed by researches from INCT for concentration of liquid radioactive waste. (author)

[en] Membrane permeation combined with complexation was tested for radioactive wastes processing purpose. The results of experiments with MEMBRALOX and CeRAM INSIDE filtering elements are presented in the paper. The pore size of ceramic membranes was in 1kD-100 nm range. The experiments were performed with non-active and with radioactive model solutions and original radioactive waste samples. To achieve high decontamination factors the process was enhanced by chemical complexation. Such complexants as poly(acrylic) acid and polyacrylic)acid salts of different crosslinking, polyethylenimine and cyanoferrates were tested. The experiments showed the significant increase of retention and decontamination factors while before ultrafiltration macromolecular ligands were added. The effectiveness of complexation by each ligand is strongly dependent on pH and alkali metals concentration. (author)

[en] The results of studies on application of selected membrane processes, such as reverse osmosis (RO), ultrafiltration (UF) and membrane distillation (MD) in nuclear technologies and mathematical modeling were presented in the report. The classical approach basing on thermodynamics of irreversible processes was used for RO modeling. The parameters of Kedem-Katchalsky model were determined on the basis of the own experimental results concerning water desalination and radionuclides separation from liquid radioactive wastes. The results of application of polymer enhanced ultrafiltration for radioisotopes removal from water solution were presented. Ultrafiltration enables the higher flux to be achieved comparing with reverse osmosis. The good separation effect of small molecules on UF membranes has been achieved by complexation with water-soluble polymers. The concentration polarization gel model was used to determine maximum attainable solute concentration in the retentate. Membrane distillation was applied for radwastes concentrating and water desalting. The mass and heat balance equations enabled the real temperature difference and heat transfer coefficients to be determined on both sides of the membrane, as well as temperature polarization coefficients. The multistage membrane distillation systems demonstrate the significant enhancement of separation efficiency of isotopes. The analysis of cascade systems for ¹⁸O enrichment have been performed. (author)

[en] A method of radioactive waste concentration by membrane distillation is presented. The temperature gradient between membrane surfaces which are in contact with two streams, warm and cold causes water flow through a hydrophobic membrane. Radionuclides and other impurities are concentrated in the warm stream (retentate). A pilot plant equipped with spiral-wound PTFE module G 4.0-6-7 (SEP GmbH), approx. 0.03 m³/h of capacity, was built. The results of pilot plant experiments were described in the paper. (author)

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[en] The treatment of radioactive wastes is necessary taking into account the potential hazard of radioactive substances to human health and surrounding environment. The choice of appropriate technology depends on capital and operational costs, wastes amount and their characteristics, appointed targets of the process, e.g. the values of decontamination factors and volume reduction coefficients. The conventional technologies applied for radioactive waste processing, such as precipitation coupled with sedimentation, ion exchange and evaporation have many drawbacks. These include high energy consumption and formation of secondary wastes, e.g. the sludge from sediment tanks, spent ion exchange adsorbents and regeneration solutions. There are also many limitations of such processes, i.e. foaming and drop entrainment in evaporators, loses of solvents and production of secondary wastes in solvent extraction or bed clogging in ion exchange columns. Membrane processes as the newest achievement of the process engineering can successfully supersede many non-effective, out-of-date methods. But in some instances they can also complement these methods whilst improving the parameters of effluents and purification economy. This monograph presents own research data on the application of recent achievements in the area of membrane processes for solving selected problems in nuclear technology. Relatively big space was devoted to the use of membrane processing of low and intermediate radioactive liquid wastes because of numerous applications of these processes in nuclear centres over the world and also because of the interests of the author that was reflected by her recent research projects and activity. This work presents a review on the membrane methods recently introduced into the nuclear technology against the background of the other, commonly applied separation techniques, with indications of the possibilities and prospects for their further developments. Particular attention was paid to the pressure-driven processes, e.g. ultrafiltration and reverse osmosis, which were studied on a laboratory and pilot scale. Verification of the potential application of reverse osmosis on an industrial scale for treatment of liquid low- and intermediate-level radioactive wastes has been carried out with the installation particularly designed and constructed for the Department of Radioactive Waste Processing, Institute of Atomic Energy at Swierk. The thin-layer composite membranes made from a cross-linked aromatic polyamide of high retention of NaCl (99,4-99,7%) were applied in this process. It has been proved that a three-stage installation enables the radioactive waste of specific radioactivity below 10⁵ Bq/dm³ to be cleaned down to 10 Bq/dm³ in permeate, with simultaneous 7-15-fold reduction of the activity in the concentrate. The results of own studies concerning the removal of selected radionuclides from model aqueous solutions and radioactive wastes with ultra-filtration enhanced by complexation and sorption were also presented in this work. In these cases, the mineral (ceramic) porous membranes made from a-alumina, titanium and zirconium oxides were applied. These membranes exhibited a high resistance against ionizing radiation, aggressive chemical environment and high temperatures. The high effectiveness of removal of the main components of liquid radioactive waste like ¹³⁴Cs, ¹³⁷Cs, ⁶⁰Co, ¹²⁴Sb, ⁸⁵Sr, ¹⁵²Eu and ¹⁵⁴Eu with a hybrid ultrafiltration/complexation process has been experimentally proved. The effects of this type of complexing agent, its concentration and pH of the processed solution on the complexation effectiveness have been studied. Efficacy of the method was tested with real radioactive wastes. The monograph performs results of the studies on membrane distillation which has been proposed by the author for processing of liquid radioactive wastes, and the analysis of its applicability for nuclear desalination and the production of pure water for power industry purposes. The membranes made from polytetrafluoroethylene and polypropylene were used in the case of membrane distillation. It was proved that membrane distillation is an efficient process in radioactive waste processing, enabling complete purification of the effluent and high volume reduction. The flow-sheet of integrated system for the purification of low and medium level radioactive wastes, combined with nuclear desalination by the membrane distillation method for the purpose of nuclear power plant, has been elaborated. The experimental results on the application of membrane processes for tritium removal from aqueous solutions were also presented. The pressure-driven process (ultrafiltration), as well as the processes with phase transition, namely pervaporation and vacuum enhanced membrane distillation were applied in that case. The polymer membranes made from modified polysulphone and regenerated cellulose, as well as porous polytetrafluoroethylene membranes were used for the purpose of tritium separation from aqueous solutions. The prevailed contribution of the Knudsen diffusion to the observed separation effects with the application of porous polytetrafluoroethylene membranes has been proved. The final conclusions comprise the characteristics and comparison of the applied membrane methods and the evaluation of their efficiency. Both the results of the performed research and the literature studies indicate directions and opportunities of potential applications of these methods in nuclear technologies. (author)

[en] The aim of the Conference was to offer an opportunity to interchange views and experiences, as well as to present the state of the art and modern trends concerning research and applications in the field of nuclear technologies. It was hoped that the Conference may fill up the gap on the field of information about possibilities and results of the application of nuclear technologies in modern economy of the 21 century, particularly in: industry, food processing, heritage preservation, environmental protection, homeland security and health protection. One session, with invited lectures, was entirely devoted to modern nuclear technologies for power generation. Conference participants presented 7 plenary lectures, 68 oral communications in 8 sessions and 98 posters

No abstract available