Molten salt test system reaches operational milestone

Flibe is a chemically stable mixture of lithium, fluorine, and beryllium that will be used as the coolant for Kairos's fluoride salt-cooled high-temperature reactor, the KP-FHR. The company is following an iterative approach to development: the non-nuclear ETU was built at the company's testing and manufacturing facility in Albuquerque, New Mexico, to demonstrate the design and integration of key systems, structures, and components, exercise the supply chain, and accelerate the company's experience with large-scale Flibe operations.

Kairos produced 14 tonnes of Flibe for the ETU at the Molten Salt Purification Plant MSPP in Elmore, Ohio, in partnership with Materion Corporation, itself the first plant ever built to produce Flibe at an industrial scale. The Engineering Testing Unit has also catalysed the development of other critical infrastructure for Kairos Power, the company said, as well as initiating the supply chain for specialised materials and components, and so mitigating development risk.

Kairos said it was collecting "an abundance of data" from the ETU operations, which have included amongst other things the removal and inspection of surrogate fuel pebbles via the integrated Pebble Handling and Storage System to demonstrate the feasibility of online refuelling and commissioning a first-of-its-kind chemistry control system to continuously monitor the purity of the molten salt circulating inside the unit. The system is continuously monitored from two control rooms, one co-located with ETU in Albuquerque and one at the company's headquarters in Alameda, California.

"Gaining experience with Flibe production and operations is fundamental to taking risk off the table towards KP-FHR commercialisation," Kairos Power co-founder and CEO Mike Laufer said. "Iterative development with real hardware systems like ETU 1.0 is a pillar of our strategy to deliver a clean, safe, affordable technology with true cost certainty, and, when combined with in-house manufacturing, provides a unique opportunity to move quickly so we can make an impact in the fight against climate change."

The ETU began operations in the autumn and is expected to run for about five months. Once testing is complete, this first iteration of the ETU - ETU 1.0 - will be decommissioned to make way for ETU 2.0, which will demonstrate modular construction. A final iteration, ETU 3.0, will be built adjacent to the Hermes site in Oak Ridge, Tennessee.

The US Nuclear Regulatory Commission recently approved Kairos's application to build Hermes, a 35 MW (thermal) non-power version of the KP-HFR, with the company aiming to begin construction this year.

Learnings from the ETU will inform the Hermes demonstration reactor project (Video: US Department of Energy)