Failure Reason of Metal Trash Net in a Nuclear Power Plant

The failure of the metal trash net in a nuclear power plant was analyzed. The site investigation found that the copper alloy mesh was broken and the steel buoy was damaged. The failure mechanism of the metal trash net and steel buoy was analyzed by optical microscopy and scanning electron microscopy. The results show that the composition of the failed metal trash mesh (Cu-Zn alloy) was inconsistent with the composition described by the manufacturer (Cu-Al alloy). Decomposition corrosion of Cu-Zn alloy occurred, and the corrosion accelerated under the action of stress and microorganisms, resulting in rapid fracture. The corrosion mechanism of decomposition corrosion was preferential dissolution. The damage of the steel buoy was mainly caused by galvanic corrosion. Corresponding protection measures were proposed for copper alloy trash net served in marine environment.