The research report of the risk assessment and treatment of PbSCC in 800 alloy heat transfer tube of NPP's steam generators

Through the study of the latest foreign experience and results, the author preliminarily determines that the probability of lead induced stress corrosion cracking (PbSCC) of 800 alloy heat transfer tubes of TQNPP's steam generators is larger. The results of simulated immersion test of 800 alloy shows that the susceptibility of PbSCC in 800 alloy heat transfer tubes is very larger. The investigation of lead sources reveals that the main source of lead is the dissolution of lead in the material of secondary circuit and the use of leaded tools or articles, the investigation also finds that there is obvious lead deposition in the steam generator secondary side. In order to solve the problem, a series of countermeasures are studied and developed to reduce the stress corrosion susceptibility of 800 alloy lead and the rupture risk of heat transfer tubes. (author)