Following the integration of 3D printing as part of its digital services portfolio, Siemens claims that is has completed the first installation a 3D-printed part in a nuclear power plant. The replacement part produced for the Krško nuclear power plant in Slovenia is a metallic, 108 mm diameter impeller for a fire protection pump that is in constant rotating operation. The water pump provides pressure for the fire protection system at the plant. The original impeller was in operation since the plant was commissioned in 1981; its original manufacturer is no longer in business.
Designs impossible to obtain
Obsolete, non-OEM parts are particularly well-suited for this new technology as they and their designs are virtually impossible to obtain. This technology allows mature operating plants to continue operating and achieving or, as in the Krško case, even extending, their full life expectancy. Siemens reverse-engineered and created a 'digital twin' of the part. The company's additive manufacturing (AM) facility in Finspång, Sweden, then applied its advanced AM process using a 3D printer to produce the part. Meeting the Krško NPP's stringent quality and safety assurance requirements required extensive testing that was performed jointly with the Krško operations team over several months, ensuring that the new 3D-printed part would perform safely and reliably. Further material testing at an independent institute as well as a CT scan, showed that the material properties of the 3D-printed part were superior to those of the original part.
High ranking plant
The Krško plant is among the highest-ranked of European nuclear power plants by the European Nuclear Safety Regulators Group in terms of safety according to assessments following Fukushima. It provides more than one-quarter of Slovenia's and 15% of Croatia's power, making it vitally important to the region. For over a decade, Siemens has been performing modifications and providing service on the plant's non-nuclear side, including turbine, generator and auxiliary equipment. Siemens and Krško plan to continue research and development in this area and are looking at advancing the design of parts that are most difficult to produce using classical manufacturing techniques, such as lightweight structures with improved cooling pattern.