Specific features of corrosion-mechanical damages of primary circuit header to steam generator vessel branch welds at VVER-1000 NPPs and their impact on safety and economic efficiency during long-term operation are analysed. Measures to avoid the damages for similar zones of VVER-1200 steam generators are discussed.
The problem of premature failure of bearings is a common type of failure. In most cases, the destruction occurs due to violation of operating conditions. Since the destruction of bearings is a frequent occurrence, consideration of this special case of destruction in the future will help to avoid such problems. The object of research is the screw compressor bearings destroyed during operation. To identify the causes, a collapsed bearing was examined and a bearing that did not collapse during operation.
Lacquered copper membranes are sometimes used in operate equipment containing low aggressive corrosive water-based fluids. In some cases, the lacquer coating does not prevent the occurrence of corrosive processes leading to through damage to the product and equipment failure. In this work, a review of the most common copper corrosion mechanisms is carried out. During a visual inspection of the products, the peculiarities of the state of the membrane surfaces and corrosive damage were noted. On the basis of metallographic, X-ray structural and electrochemical studies, the assumptions put forward at the stage of visual inspection were confirmed. The conclusions contain assumptions about the reasons for the formation of pitting corrosion on copper membranes.
IAEA activities on ageing management started in 1990 are a part of NPP Units life management or License Renewal as specified in national regulatory documents of member countries. Development of digital technologies makes it possible to manage lifetime NPP Unit issues in effective manner by application of Digital Twin.
This paper presents the results of analyzing the reasons for damage to the plunger stem and cylinder of sucker rod pumps, which were operated in an environment with hydrogen sulfide. The chemical composition, mechanical properties, and hardness of the products were studied in order to assess how the material of the parts conforms to the technical documentation. Likewise, the reasons for damage were analyzed using an optical electron microscope. It was established that damage to the plunger stem happened along the first thread of the threaded connection of the rod inside the body of the adapter, while destruction to the cylinder was observed in the area of the threaded connection to the body of the pump’s suction valve. Results showed that the main reason for damage was the combination of a corrosive H2S environment and mechanical stress, which led to sulfide corroded cracking under stress. Suggestions were put forward about extending the service period of the SRP parts and reducing the likelihood of their destruction.
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