| Abstract Scope |
Metallic hydrides are gaining prominence in advanced nuclear systems due to their exceptional and unique ability to store hydrogen in a highly dense, solid form. These materials play multifaceted roles, including acting as high-density moderators in microreactors and space fission power systems. This is in addition to providing in-core hydrogen supply and lightweight radiation shielding in nuclear thermal propulsion applications. This work presents a scalable and cost-effective additive manufacturing (AM) approach for fabricating complex hydride geometries tailored for advanced reactor moderators. A custom-built liquid deposition modeling (LDM) 3D printer was used to extrude a carboxymethyl cellulose (CMC)-based hydrogel binder containing 316L stainless steel powder as a surrogate for yttrium or other suitable, non-stoichiometric-hydride-forming-metals. The surrogate powder provides a safe and flexible platform for developing and testing sintering and hydriding conditions before introducing metallic yttrium. The printer’s motion system features an XY-linear movement print bed with Z-only extruder, improving rigidity and print accuracy across the printer envelope compared to traditional gantry designs. Our approach integrates a statistical CMC-mixture design and employs eco-friendly hydrogel synthesis to enhance printability and material properties. The optimized low-cost printer configuration and mixture enabled direct printing of complex parts, the surrogate metal, and with post-printing sintering, a final part density above 2.24 g/cm^3 was achieved. Future work will incorporate yttrium powder, optimize hydriding protocols, and evaluate microstructural and mechanical performance under irradiation-relevant conditions. |