[en] Membrane processes nowadays become common techniques in nuclear technologies. Various membrane methods were applied in nuclear centers in the world, including full-scale installations operated in continuous mode and cleaning different kinds of radioactive waste. The newly constructed membrane apparatus that changes the hydrodynamic conditions in the module and promotes turbulence, allows increasing efficiency of separation and reduction of the membrane fouling. The advantages of helical apparatus with porous tubular membrane are expected in: (a) simplicity of the construction in comparison with dynamic filtration by use of rotating discs; (b) high mass transfer coefficients to the membrane surface; (c) good effects of mixing, especially when the rotor is asymmetrically assembled or pulse flow is applied; (d) the possibility of replacement of the rotating shaft by spiral insert creating helical flow. It has been shown, that the apparatus can be used as a filtration stage after formation of precipitate or metal complexes, as well as a membrane contactor in the process of solvent extraction used for radioactive waste processing

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[en] Asymmetric rolling is used to modify material properties and to reduce forces and torques applied during deformation. This geometry of deformation is relatively easy to implement on existing industrial rolling mills and it can provide large volumes of a material. The results of the study of microstructure and crystallographic texture in asymmetrically rolled aluminium 6061 and titanium (grade 2) are presented in this work. These characteristics were determined using the EBSD technique and X-ray diffraction. The rolling asymmetry was realized using two identical rolls, driven by independent motors, rotating with different angular velocities. It was found that asymmetric rolling leads to microstructural refinement and texture rotation (around the transverse direction). The impact of asymmetric rolling on microstructural refinement appears also in recrystallized samples of both materials. On the other hand, texture rotation, caused by asymmetric rolling, persists after annealing in titanium but not in aluminium samples. (paper)

[en] Aluminium alloy sheets were asymmetrically rolled and annealed. Asymmetric rolling was applied by imposing different velocity ratios between the top and bottom rolls, from 1 to 1.5. After cold rolling, the microstructures of various samples were analysed by electron back scatter diffraction, whereas the mechanical properties were characterized by stress–strain curves and microhardness measurements. The asymmetrical rolling process was examined as an alternative method to obtain fine- or even ultrafine-grained aluminium. The main purpose of this paper is to describe, qualitatively and quantitatively, the influence of asymmetrical rolling on microstructure evolution. Grain size, misorientation, image quality factor and other parameters were characterized and analysed in some detail. In the present study, a unique approach has been used for the first time to examine the possibility of applying the asymmetric rolling process in the preparation of materials with controlled heterogeneity

[en] Membranes used for filtration of industrial wastes that contain particles, colloids, macromolecules, etc., are susceptive to fouling. The processing of liquid radioactive wastes involves some interim stages like precipitation, coagulation or flocculation that are followed by filtration techniques. The hybrid complexation-ultrafiltration or sorption-ultrafiltration methods used in the Institute of Nuclear Chemistry and Technology, Warsaw (PL) for radioactive wastes treatment was proved as a feasible method for separation of the main components of the wastes originating from production and application of isotopes. Model solutions and real radioactive waste samples were used in experiments. To bind small ions as the most common components of liquid radioactive wastes: Cs⁺, Co²⁺, Sr²⁺ or lanthanides, the soluble polymers like polyethylenoimine or polyacrylic acid were applied, as well as suspensions of hexacyanoferrates, manganese oxide and hydrous titanium oxide. The experiments showed that in a short time the flux decline caused by concentration polarisation appeared in all membrane systems tested. The flux decline took place until the moment when the steady-state conditions were attained and the flow rate through the membrane stabilised. In experiments with real wastes after some hours a continuous flux decline, caused by membrane fouling was observed. In several hours of operation permeate flux could decrease even in 70-80 % that corresponded with membrane clogging. Possibility to minimize membrane fouling is proposed

[en] The work focuses on the influence of moderate plastic deformation on subsequent partial recrystallization of hexagonal zirconium (Zr702). In the considered case, strain induced boundary migration (SIBM) is assumed to be the dominating recrystallization mechanism. This hypothesis is analyzed and tested in detail using experimental EBSD-OIM data and Monte Carlo computer simulations. An EBSD investigation is performed on zirconium samples, which were channel-die compressed in two perpendicular directions: normal direction (ND) and transverse direction (TD) of the initial material sheet. The maximal applied strain was below 17%. Then, samples were briefly annealed in order to achieve a partly recrystallized state. Obtained EBSD data were analyzed in terms of texture evolution associated with a microstructural characterization, including: kernel average misorientation (KAM), grain orientation spread (GOS), twinning, grain size distributions, description of grain boundary regions. In parallel, Monte Carlo Potts model combined with experimental microstructures was employed in order to verify two main recrystallization scenarios: SIBM driven growth from deformed sub-grains and classical growth of recrystallization nuclei. It is concluded that simulation results provided by the SIBM model are in a good agreement with experimental data in terms of texture as well as microstructural evolution. (paper)

[en] In some metallic materials the dominating recrystallization mechanism can be described by the oriented growth behaviour. Phenomenological laws state that in selected materials only these nuclei grow intensively which have a given misorientation relation with the deformed matrix. This description is frequently verified in f.c.c. metals and generally reported misorientations correspond approximately to 400 rotation around the <111> axis. Basing on the above ideas the recrystallization model, including the compromise condition, was formulated and applied to the study of recrystallization textures of rolled polycrystalline aluminium. (paper)

[en] Asymmetric rolling is a promising forming technique offering numerous possibilities of material properties modification and the improvement of technological process parameters. This geometry of deformation is relatively easy to implement on existing industrial rolling mills. Moreover, it can provide large volume of a material with modified properties. The study of microstructure, crystallographic texture and mechanical properties of asymmetrically rolled aluminium is presented in this work. The above characteristics were examined using EBSD technique and X-ray diffraction. The rolling asymmetry was realized using two identical rolls, driven by independent motors, rotating with different angular velocities. It was found that asymmetric rolling leads to microstructure refinement, texture homogenization and decreasing of residual stress. (paper)

[en] The qualitative and quantitative behaviour of titanium Ti40 during tensile deformation was investigated along with the effect of deformation and twins on the subsequent recrystallisation process. For this purpose, the examined material was subjected to stretching in mutually perpendicular directions. Tensile tests were performed up to 8% and 16% deformation. Subsequently, the material was examined using the electron backscatter diffraction technique. Analysis of microstructure and misorientation profiles showed that the material stretched in the transverse direction was characterised by the creation of numerous twin structures. A large number of twins {1 0 1 2}<‒1 0 1 1> was observed, whereas in the sample stretched in the rolling direction {1 1 ‒2 2}<‒1 ‒1 2 3> twin structures were rarely observed. Twin structures obtained during deformation have an impact on the process of recrystallisation, mainly on recrystallisation kinetics. This phenomenon was confirmed by the analysis of parameters such as grain orientation spread and grain sizes as a function of recrystallisation time.

[en] A new method for determining the residual stresses in two-phase material is proposed. The method is based on the diffraction measurements analysed using a model of elasto-plastic deformation. The time-of-flight neutron diffraction technique was applied to determine lattice strains and a self-consistent rate-independent model was used to predict the second-order stresses in austeno-ferritic duplex steel. As the result of analysis, the stress state and elastic energy for each polycrystalline grain was found. Finally, the influence of different parameters characterizing elastoplastic deformation on the second-order stresses was studied