Additive Manufacturing of Nuclear Grade Components

A direct laser metal sintering process will be developed that will enable the fabrication of complex stainless steel and Inconel alloy components for use in the cores of light water reactors directly from a digital model. Direct fabrication eliminates welding processes that place limits on component design and potentially affect the strength and corrosion resistance of the final component. The technology will enable designers to use qualified materials to rapidly integrate components into the current light water reactor fleet to improve both reliability and safety. The objective of the program is to demonstrate that stainless steel and Inconel alloy components can be fabricated by using a high power laser to sinter metallic powders. The energy output, the power density and the duration of heating will be controlled to demonstrate that materials can be produced with microstructures comparable to commercially available alloys used in nuclear systems. Further, it will be shown that by controlling the position of the laser that components can be built by a direct 3D printing strategy that eliminates the need for post processing and assembly procedures such as electron beam welding. A direct laser metal sintering process will be demonstrated for the direct fabrication of stainless steel and Inconel alloy components directly from a digital model. The microstructure of the materials will be shown to be controlled by adjusting the laser sintering parameters to produce materials with a microstructure comparable to that of in use nuclear components. The mechanical properties and corrosion resistance of the fabricated alloys will be shown to equal or exceed the properties of the alloys used in nuclear applications. Commercial Applications and Other Benefits: Successful demonstration of the direct metal laser sintering process for nuclear grade alloys will enable the fabrication of reactor core components that will improve the reliability and safety of nuclear systems. Specific applications include the fabrication of fuel cladding retainer structures that can reduce fuel cladding fretting wear and improve flow within the core to reduce the likelihood of cladding failure and the development of flow restrictions. The technology can be further applied to other exotic alloys used in aerospace and the industrial processing sectors to improve, for example, chemical/fuel mixing nozzles that will improve energy efficiency of propulsion systems.