US-based Kairos Power has completed design, construction, and installation of the reactor vessel for its second non-nuclear Engineering Test Unit (ETU 2.0). It is the first reactor vessel to be fabricated in-house at Kairos Power’s Manufacturing Development Campus in Albuquerque, New Mexico.
The reactor vessel is a central component of the ETU, which Kairos Power is building to advance the iterative development of its Fluoride Salt-Cooled High-Temperature Reactor (KP-FHR) technology. ETU 2.0 will demonstrate KP-FHR system integration in an optimised, fully modular design, building on lessons learned from ETU 1.0.
The ETU programme is intended to mature Kairos Power’s internal manufacturing capabilities, mitigating supply chain risk for the Hermes demonstration reactor series and Kairos Power’s commercial fleet. With ETU 2.0, the company is ramping up output of ASME U-stamped pressure vessels, advancing the production of specialised reactor components, and gaining proficiency in modular construction methods.
For the ETU 2.0 reactor vessel, Kairos Power established a dedicated shop inside its Albuquerque facility for KP-FHR vessel production, featuring large-scale plate-rolling, cutting, automated welding, and machining capabilities. The in-house engineering, procurement, and manufacturing teams collaborated closely throughout the project, enabling key learnings that will carry forward to future iterations.
Kairos Power’s goal is for 80% of ETU 2.0 costs to derive from raw materials or commercial off-the-shelf parts, following the company’s vertical integration strategy. By minimising the outsourced production of specialised components, Kairos Power expects to gain better control over product cost, quality, and schedule for the commercial fleet.
The ETU 2.0 reactor vessel is a contract milestone under Kairos Power’s Technology Investment Agreement with the US Department of Energy (DOE) for risk reduction funding through the Advanced Reactor Demonstration Program (ARDP). Under the agreement, Kairos Power receives fixed, performance-based payments from DOE by demonstrating the achievement of pre-determined project milestones. This fiscally responsible approach ensures Kairos Power only gets paid when we deliver. DOE has agreed to invest up to $303m in the Hermes reactor project through the ARDP, supplementing Kairos Power’s substantial private investment.
“We are systematically building the capabilities and know-how to self-produce major reactor components over multiple iterations – an investment that will ultimately lower costs for the commercial fleet.” Said Mike Laufer, Kairos Power co-founder & CEO
Craig Gerardi, Kairos Power Vice President of Manufacturing noted: “A little over three years ago, we identified the opportunity to vertically integrate vessel manufacturing to achieve Kairos Power’s quality, cost, and schedule goals.”
Kairos Power, founded in 2016, is headquartered in Alameda California and expanded to Albuquerque’s Mesa del Sol community in 2019 to establish its research and development engineering centre for the commercialisation of its advanced reactor technology. Kairos also has facilities in Oak Ridge (Tennessee) and Charlotte (North Carolina). In 2023, the US Nuclear Regulatory Commission issued a construction permit for Kairos Power’s Hermes demonstration reactor – the first non-water-cooled reactor to be approved for construction in the US in more than 50 years.
The Hermes design is for a 35 MWt non-power version of the company’s fluoride salt-cooled high temperature reactor, the KP-HFR. Kairos has also submitted a construction permit application for Hermes 2, a proposed two-unit demonstration plant that would build on the experience of Hermes and would produce electricity and demonstrate the complete architecture of future commercial plants. Kairos says the Hermes demonstration reactors will help to mitigate technology, licensing, supply chain, and construction risk to achieve cost certainty for KP-HFR technology. Kairos is targeting commercial deployments in the early 2030s. Hermes is to be built at Oak Ridge.
Kairos conducted salt operations at ETU 1.0 – full-scale mock-up of Hermes intended to demonstrate key systems and components of the reactor, test the supply chain, and to allow workers to gain operational experience. Kairos will build and operate a total of three ETU iterations before constructing Hermes. ETU 1.0 carried out more than 2000 hours of pumped salt operations and establish new capabilities, including the production of the high-purity fluoride-lithium-beryllium (FLiBe) salt coolant. ETU 1.0 completed operations in mid-2024.
In October 2024, Kairos broke ground on a salt production facility to produce high-purity molten salt coolant for advanced reactors at its Albuquerque campus. It also plans TRISO Development Lab at the site, where it will optimise fuel manufacturing techniques to be implemented in a new space the company is building at Los Alamos National Laboratory’s Low-Enriched Fuel Fabrication Facility. The salt coolant and TRISO (TRI-structural ISOtropic) fuel produced in these facilities will go into the Hermes demonstration reactor under construction in Tennessee.
Kairos in August 2024 began construction on the Hermes Low-Power Demonstration Reactor. Kairos contracted Barnard Construction Company to perform site work and excavation at the Hermes site in Oak Ridge. Barnard and Kairos Power have also started collaborating on construction of ETU 3 co-located in Oak Ridge that will generate supply chain, construction, and operational experience to inform the Hermes project.
Kairos has also signed an agreement with Google to support the first commercial deployment of Kairos Power’s reactor by 2030, with the aim of multiple reactors supplying electricity to Google data centres through power purchase agreements.
