3-D Printing of Nuclear Fuel Assembly Nozzles and End-Spacer Grids

Cost and time associated with material waste, quality control, inspection, and manufacturing of nuclear fuel assembly components can detrimental to nuclear plant design and development. Specifically, spacer grids and nozzles are prime component examples that inherently carry these issues due to their complex geometries. The design engineer must always weigh the manufacturing practices against the operational benefits. To combat this issue, the Department of Energy is highly interested in advancing methods of manufacturing for nuclear energy technologies that allow for easier engineering and commercial production of nuclear fuel assembly component. Proving that complex geometries, fuel assembly spacer grids and nozzles, can be manufactured with the same material (Inconel-718) using additive material technologies shows the nuclear industry that former manufacturing complications are no longer necessary. Additive material technologies also give the designer the option of adding beneficial features to spacer grids and nozzles during the Computer Aided Design (CAD) process that were previously impossible (due to tooling impediments). During Phase I, a 17x17 fuel rod array, composite lower spacer grid/nozzle will be modeled using Computer Aided Design, removing the need to produce two separate fuel assembly components. This new composite part will contain a novel fuel rod slip spring design and nozzle flow field. Once modeled, the lower spacer grid/nozzle will be analyzed using Finite Element Analysis (FEA) in parallel with public-domain 17x17 lower spacer grids and nozzle to compare structural integrity. Lastly, after structural and flow benefits have been optimized, the composite lower spacer grid/nozzle may be manufactured using additive material technologies. Using additive material technologies (i.e. metallic 3D-Printing) minimizes material waste and inspection time while producing fine-tolerance products – increasing quality – that frees the designers to focus on component operation, not manufacturing (welding, milling, stamping, etc). Proof-of-concept in Phase I will open the door for different fuel assembly parts to be manufactured in Phase II, and irradiation of 3-D printed components on a lead fuel assembly in a commercial reactor in Phase III. Key Words: Additive material technology, 3D-Printing, nuclear fuel assembly, spacer grids, core nozzles, advanced manufacturing