Kairos Power has completed the initial phase of testing for its Engineering Test Unit 3 (ETU 3) reactor mockup, located at Oak Ridge, Tennessee. This unit is part of Kairos Power's iterative development approach for its fluoride salt-cooled high-temperature reactor (KP-FHR) technology. The reduced-scale non-nuclear mockup cavity includes a reactor vessel and a precast concrete shielding structure, which utilizes 3D-printed polymer composite forms developed with Oak Ridge National Laboratory’s (ORNL) Manufacturing Demonstration Facility. These components are supported by steel frames.
Each panel in the ETU 3 demonstration incorporates steel-framed openings designed to test various concrete shielding plug designs. These plugs allow process lines from the reactor to pass through the shielding structure to other plant areas. A remote handling system will be used to connect and disconnect these lines, aiming to minimize operational disruptions.
Ed Blandford, Kairos Power co-founder and Chief Technology Officer, stated that the completion of this initial demonstration at ETU 3 is an important step toward establishing a sustainable maintenance concept for the future fleet. He emphasized that demonstrating the interfaces between modular shielding structures and reactor equipment, and testing remote handling tools for component maintenance and replacement, provides a better understanding of design features that will be standardized in commercial KP-FHR deployments.
ETU 3, the third engineering test unit in the program, will inform the next iterations of the Hermes 2 reactor cavity design and serve as a training platform for future operators. Kairos Power broke ground for Hermes 2 on the former Oak Ridge Gaseous Diffusion Plant footprint in April. The Hermes Low-Power Demonstration Reactor (Hermes 1), a scaled demonstration reactor, is also under construction at Oak Ridge. Hermes 1, the first non-light-water reactor approved for construction by the US Nuclear Regulatory Commission, will not produce electricity but will provide lessons for Hermes 2.
Previous test units include ETU 1.0, a full-scale, electrically heated prototype of the Hermes reactor, which completed over 2,000 hours of pumped salt operations. This unit demonstrated the design and integration of key systems, exercised the supply chain, and established new capabilities, including the production of high-purity fluoride-lithium-beryllium (FLiBe) salt coolant. ETU 2.0, a non-power unit, followed to demonstrate modular construction methods.