Recently, Fangchenggang nuclear power No.1 unit steam generator by Dongfang Electric (Guangzhou) Heavy Machinery Co. Ltd. which is composed of alloy 690 U-shaped heat transfer tubes made by Baosteel successfully completes hydrostatic test before going out of factory and will be put into use. It marks that nuclear steam generator alloy 690 U-shaped heat transfer tube achieves localization and industrialization formally.
It is known that the steam generator hydrostatic test includes primary and secondary side hydrostatic test and its purpose is to conduct test on steam generator strength and tightness. Primary side hydrostatic test pressure is raised to 22.8 MPa test pressure and remain 32 minutes. Then it returns to 17.13 MPa design pressure and remain 4 hours. During pressure holding period it does inspection. In secondary side hydrostatic test, the pressure is raised to 12.8 MPa test pressure and remains for 33 minutes, then it returns to 8.5 MPa design pressure and remains for 4 hours. During pressure holding period it does inspection. During the rigorous inspection, it is found that No. 1 Unit steam generator tube and tube sheet welding seam do not have any sweating, leakage and abnormal deformation and fully meet the design requirements. Among them, steam generator key pressure part - U-shaped heat transfer tube is developed and produced by Baosteel and this is also the first time that domestic nuclear power project adopts domestic alloy 690 U-shaped heat transfer tubes.
Nuclear steam generator alloy 690 U-shaped heat transfer tube is a key nuclear component in million-kilowatt nuclear power plant steam generator. Its manufacturing process requirement is extremely demanding and manufacturing process is extremely complex. Alloy 690 U-shaped heat transfer tube developed and produced by Baosteel has a number of invention patents and innovation points, representing the top level in current international nuclear tube manufacturing. Previously, only three countries can produce it: France, Japan, Sweden.
To break foreign monopoly on nuclear power steam generator alloy 690 U-shaped heat transfer tube, in 2007, Baosteel, Jiangsu Yinhuan, China Guangdong Nuclear Power Group Co., Ltd. jointly invested and set up Baoyin Special Steel Tube Co., Ltd.. It constructed the first domestic nuclear power steam generator heat transfer alloy 690 U-shaped tube professional production line and tackled a series of technical problems such as vacuum smelting, electroslag remelting, forging, hot extrusion and molding and bending. It has obtained nuclear 1st level hot extrusion tube manufacturing license and nuclear 1st level finished U-shaped heat transfer tube manufacturing license issued by National Nuclear Security Administration.
The success of Fangchenggang nuclear power plant No. 1 unit steam generator hydrostatic test indicates that the quality of alloy 690 steel U-shaped heat transfer tube produced by Baosteel has reached or even exceeded imported tube. This is another important milestone in China's nuclear key component of localization.
