US uses high-precision 3D printing for Gen IV nuclear reactor parts

The United States is pioneering the use of high-precision 3D printing to create polymer forms for concrete components in advanced nuclear reactors, marking a shift away from traditional steel or wood molds. At Kairos Power’s Oak Ridge campus in Tennessee, these 3D-printed molds are being employed for the Janus shielding demonstration, a test precursor to building parts of the Hermes Low-Power Demonstration Reactor. Hermes is notable as the first advanced reactor to receive a construction permit from the US Nuclear Regulatory Commission. The printed forms, each about 10 feet square and stacked three high, are used to cast the reactor’s bioshield—a thick concrete structure designed to absorb radiation and protect workers during operation. This additive manufacturing approach offers a cost-effective and time-efficient alternative to conventional methods, enabling the construction of complex geometries with high structural integrity under the pressure of wet concrete. The project, a collaboration involving Oak Ridge National Laboratory (ORNL), Kairos Power, and the Manufacturing Demonstration Facility (