Additive manufacture of 3 inch nuclear safety class 1 valve by laser directed energy deposition

The additive manufacturing (3D printing) technique, which is feasible for customized, small-scale production, is emerging, and it will be possible to effectively and quickly maintain the industrial facilities of nuclear power plants by replacing parts via ready-made, large-scale production. The 3-inch nuclear safety class 1 valve is a typical safety-grade part used in the pressurized light water reactor. It is difficult to manufacture by conventional laser powder bed fusion (L-PBF) methods because the valve body part weighs 30 kg, has a length of 300 mm, and flow path shape is inside. Therefore, structural stability is a problem and too many non-removable supports are needed. It can be manufactured by means of L-DED with five-axis operation and CNC (Computer Numerical Control) machining, and this method shows satisfactory performance outcomes in terms of dimensional accuracy, assembly, and joining. With this successful fabrication method, mechanical performance tests specifically room-temperature/high temperature tensile, fatigue, and radiographic tests are performed and the detailed process of manufacturing prototypes is described.