Experimental Bench Tests on the Corrosion Resistance and the Environmental Safety of Structural Materials of the Cooling System of Nuclear Power Plant

Biological pollution creates significant obstacles in the operation of power plants' technical water supply cooling systems (SCS). To minimize biological pollution, methods of corrective treatment with biocides are implemented. While these biocides effectively prevent fouling of the cooling system, they can also adversely affect the environment and structural materials. By evaluating structural materials' corrosion resistance and biocides' environmental safety for the cooling water during biocide treatment, any potential issues can be identified and addressed before they become a safety or operational concern. The paper presents the results of bench tests of the corrosion resistance of structural materials SCS, corrosion aggressiveness of the biocides: sodium hypochlorite NaClO and 2, 2-dibromo-3-nitriloropionamide (DBNPA), and the results of measurements of the concentration of biocides and their decomposition products to assess compliance with environmental standards when discharging return water when applying from biocides treatment. The cooling water SCS of the Rivne NPP (Nuclear Power Plant) was chosen as the research object. Bench corrosion tests were carried out using samples of corrosion indicators from materials: steels Ст20, 08Х18Н10Т; copper alloy МНЖ-5-1 and aluminum, which are defined as analogs of structural materials of the technical water supply system of the Rivne NPP. The conditions of operation of the technical water SCS of the Rivne NPP were simulated on the test bench, and corrosion rate measurement was carried out by the gravimetric method.