The paper considers filtration equipment used for coolant purification in WWER-1000 reactors, which plays an important role in providing an optimal water-chemical regime, reducing radioactive contamination of equipment and extending the service life of reactor components. The operating features of ion-exchange filters are investigated and directions for their modernization are determined. The design and characteristics of cation exchange filters are analyzed and key factors affecting their efficiency are highlighted, including the replacement of ion-exchange resins and optimization of the regeneration process. A comparative analysis of nuclear-grade ion-exchange resins, such as Lewatit MonoPlus S 108 H, Purolite® NRW100 and DIAION™ SKN1, is carried out, and their suitability for cation exchange filters modernization is evaluated. Cation exchange filter parameters are calculated for different ion-exchange resins, such as operational exchange capacity, intervals between regenerations and acid amount for filter regeneration. It was determined that Lewatit MonoPlus is the optimal resin for cation exchange filters due to its higher exchange capacity (2 g-eq/L), longer intervals between regenerations (22 regenerations per year) and lower cost.
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