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The Research Centre Řež operates the LVR-15 light-water research reactor with an operational thermal output of 10 MW. The reactor is used for experimental purposes and for the production of radioisotopes for medical and industrial applications. The system includes a storage pool B used for long-term storage of materials used in irradiation (e.g., probes or irradiation channels). In most cases, this material is made of aluminum or steel.
Water in storage pool B of the LVR 15 research reactor shows persistently elevated concentrations of iron and aluminium, caused by gradual corrosion of metallic materials stored in the basin. The aim of this work was to experimentally evaluate the potential for reducing these concentrations using pressure driven membrane filtration with polymer membranes (MCE, NYL) of various pore sizes ranging from 3.0 to 0.22 µm. Filtration was tested at three pH values (acidic, neutral, alkaline) and under conditions of artificially increased iron concentration to verify the formation of colloidal particles and their potential for more efficient separation.
The results demonstrated that filtration efficiency strongly depends on pH and on the chemical forms in which Fe and Al occur in solution. At the natural pH (~5.8), both iron and aluminium were effectively removed at pore sizes of 0.8–1.2 µm due to the presence of insoluble hydroxide species. In contrast, under acidic conditions (~2.7), both elements were present predominantly in soluble ionic forms and were therefore not retained by any of the tested membranes. In alkaline conditions (~11.3), iron removal was highly efficient, with concentrations falling nearly to zero when using 0.22 µm nylon membranes. Aluminium, however, remained primarily in stable soluble complexes under the same conditions, and even the smallest pores did not achieve significant retention. After the addition of 5 mg/L of iron, aluminium removal improved, likely due to co coagulation, while iron removal remained limited.
The study shows that membrane filtration can be an effective method for reducing iron concentrations in water from storage pool B, particularly under alkaline conditions. The efficiency for aluminium is significantly restricted by its speciation and the formation of stable soluble complexes. A combination of membrane filtration with controlled pH adjustment or coagulation processes appears to be a promising direction for further optimisation.