July-August 2018 NPJ

Problems Encountered The original impellers were made of nickel aluminum bronze material, leaving them difficult to weld. Though stainless material would be more repairable and ideal for welding, the client desired to have the same material as the original for the new pieces. It is not easy to make an engineering change at a nuclear plant and it also would have been very expensive. The original material provided four decades of service, and the plant found that to be proof enough for continued use. Meeting Performance Requirements Through Reverse Engineering Hydro re-engineers critical pumps in a nuclear power plant to meet original design requirements Solutions Recommended To restore the impellers to their original condition, Hydraulic engineers scanned them with the ROMER absolute arm, and created 3D models. Once a casting was produced, Hydro engineers created a 3D model over the new casting. Through reverse engineering, they could compare the 3D model taken from the produced impeller to the original design in order to ensure the designed performance was established and maintained. A final hydraulic analysis confirmed that the hydraulic performance was maintained and the requirements of the plant were met. Overview One of the many issues that fall onto nuclear power plants is impeller wear. In this case, a circulating water pump had difficulties meeting performance requirements. The condensate pumps were showing end-of-life wear after four decades of continuous use. Hydro was commissioned to re-engineer and replace two of the twelve pumps at the facility. Two original impellers were sent to Hydro to start the repair process. SPECIAL ADVERTISING SECTION