Study On The Safety Assessment Methods For The Steam Generator Tubes In The Nuclear Power Plant

The steam generator is one of the key equipments in pressurized water reactor nuclear power plant. The localized corrosion/thinning and mechanical wear are two causes leading to the decrease in the bearing capacity reduced and the following rupture of an evaporator. If an evaporator is ruptured, it will result in a series of safety problems such as an emergency shutdown of a nuclear reactor. This paper concerns the strength of defective heat exchanger tubes in the evaporator and proposes a safety assessment method for the tubes, which is safe, reliable and easy to use. The work and the results are summarized as follows:(1) An elastic finite element analysis was carried out for Incoloy800 heat exchanger tube and was validated by comparing with the theoretical result.(2) Based on the comparison between the experiment and the numerical simulation, a set of flow stress data was reasonably determined. It shows that a conservative value for burst pressure will be obtained from FEA by using this set of flow stress data.(3) The effect of the dimensions in all directions of the volume defect on the burst pressure of the pipe was studied.(4) For Incoloy 800 heat transfer tube ofΦ22×1.22mm, the two-level defect assessment method was given. This method can be used with the current detection methods, and make the technical preparations for full use of defective heat transfer tubes.