Potential and application scenarios of additive manufacturing processes in the production of SMRs and microreactors

Abstract Small Modular Reactors (SMRs) and microreactors are discussed as a low-carbon means of meeting rising electricity demand while supporting grid stability. Their economic case rests on serial factory production, high functional integration, and simplified components, goals that conventional forging, ring rolling, and welding routes can meet only with difficulty. This contribution outlines safety relevant aspects of additive manufacturing (AM) for SMR and microreactor components and presents the investigation programme of the SiFeKo junior research group at the Materials Testing Institute (MPA), University of Stuttgart. Two processes are considered: laser powder bed fusion of metals (PBF-LB/M) and wire-based directed energy deposition (DED-Arc). For PBF-LB/M, the focus is on whether functionally integrated liquid-metal heat pipes can be realized, with internal capillary structures such as lattices, grooves, or interconnected porosity built into the wall and adapted to working fluid, orientation, and local heat flux. For DED-Arc, large, thick-walled structural and pressure-vessel components are addressed, motivated by high deposition rates, efficient wire use, and the prospect of fewer weld seams; thermo-mechanical process simulation is intended to predict distortion and residual stress. For both processes the open challenges are set out: residual stress and distortion, process-induced defects such as lack of fusion, porosity, and slag inclusions, anisotropy, powder removal, and demanding non-destructive inspection and qualification. AM is also considered against historical precedents and current nuclear regulation. The work defines the open questions that future investigations must resolve before AM can be qualified for nuclear service.