The initial iteration of an engineering test system for Kairos Power’s Hermes low-power reactor, known as Engineering Test Unit 1.0 (ETU 1.0), has been decommissioned after successfully completing over 2,000 hours of pumped salt operations. Construction is underway for the next iteration, ETU 2.0, which will demonstrate the modular design of the reactor.
Largest FLiBe Molten Salt System
ETU 1.0 is the largest FLiBe molten salt system constructed to date. This accomplishment represents a significant step forward in the development of advanced nuclear reactor technology.
ETU 1.0 is the first of three systems designed to inform the development of Hermes, Kairos Power’s fluoride salt-cooled high-temperature reactor (KP-FHR).
Hermes, which receives support from the U.S. Department of Energy’s Advanced Reactor Demonstration Program (ARDP), will employ a TRISO fuel pebble bed design with molten fluoride salt coolant to achieve a thermal power level of 35 megawatts.
Rapid Iterative Development Approach
ETU 1.0 is part of Kairos Power’s “rapid iterative development” strategy, which involves designing and building multiple prototypes.
As a full-scale, electrically heated prototype of Hermes, ETU 1.0 allowed Kairos Power to strengthen its supply chain and establish new capabilities. This included the production of high-purity FLiBe and specialized reactor components.
Testing Operations and Conditions
ETU 1.0, based in Albuquerque, New Mexico, began operations in December 2023. The system was filled with 12 tons of FLiBe, produced in partnership with Materion Corporation, along with 30,000 surrogate fuel pebbles and over 300 graphite reflector blocks.
This setup simulated the conditions inside the Hermes reactor core. Over six months, the system conducted over 2,000 hours of pumped salt operations, including regular operations and tests simulating failure scenarios. It reached a peak temperature of 675°C and a salt flow rate of over 11,300 liters per minute.
Extensive Data Collection
The test unit was continuously monitored, amassing over 10 terabytes of performance data. This data, combined with analysis of salt samples and inspections of surrogate fuel pebbles, provides valuable insights for future reactor development.
Edward Blandford, Kairos Power’s Chief Technology Officer and co-founder, emphasized the importance of learning through building and highlighted the significant knowledge gained from ETU 1.0.
Construction of ETU 2.0 is underway in Albuquerque. ETU 3.0 will be built in Oak Ridge, Tennessee, near the planned Hermes reactor site. Kairos Power aims to have the Hermes reactor operational as early as 2026, paving the way for commercializing the 140 MWe KP-FHR.