Kairos Power begins loading 14 tons of FLiBe into molten salt test loop

November 17, 2023, 9:30AMNuclear News
The Engineering Test Unit at KP Southwest. (Photo: Kairos Power)

In October, staff at Kairos Power’s testing and manufacturing facility in Albuquerque, N. M., began transferring 14 tons of molten fluoride salt coolant into an Engineering Test Unit (ETU)—the largest transfer of FLiBe (a mixture of lithium fluoride and beryllium fluoride) since the Molten Salt Reactor Experiment in 1969.

The work: Scaled at the same size as the Hermes demonstration reactor planned for construction in Oak Ridge, Tenn., and with similar operating parameters, the ETU is a nonnuclear prototype of Kairos Power's fluoride salt–cooled, high-temperature reactor (KP-FHR), built to demonstrate the integration of principal systems, structures, and components.

Because FLiBe is not commercially available, Kairos Power produced the salt in its custom-built Molten Salt Purification Plant in Elmore, Ohio, on the campus of the specialty materials company Materion. The last batch was trucked in solid form to the New Mexico location—known as KP Southwest—in August.

“Being the first to build and operate a plant to produce FLiBe at an industrial scale has generated a wealth of lessons that will help de-risk salt production for future iterations,” the company said in a November 16 newsletter.

In action: To load the salt into the ETU, operators must individually preheat each transport canister containing two tons of solid FLiBe. The canisters then are moved individually onto a loading station, where argon gas is used to push the molten FLiBe into the ETU’s intermediate storage tank.

Operators can monitor the system from two control rooms—one co-located with the ETU at KP Southwest and one at Kairos Power headquarters in Alameda, Calif. The control rooms display real-time data on temperatures, pressures, oxygen levels, moisture readings, and the decreasing weights of the FLiBe canisters as their contents flow into the system.

What’s next? Once all 14 tons of FLiBe are circulating in the ETU, a “multimonth testing program” will commence and “continue to provide learnings and data until the system is decommissioned to make way for the next iteration—ETU 2.0,” according to Kairos Power.

The company plans to demonstrate modular construction of the ETU 2.0 by building each subsystem as a modular skid. Those skids will allow subsystems to be tested and qualified in parallel before they are moved into the ETU enclosure for assembly, which will allow staff to move forward on construction of ETU 2.0 while ETU 1.0 operations and decommissioning are still in progress, Kairos Power said. This summer, the team began construction on the Modular Systems Facility to support ETU 2.0 subsystem development.

An ETU 3.0 is also planned, but unlike the ETU and ETU 2.0, it would be constructed on land owned by Kairos Power adjacent to the Hermes site at Heritage Center Industrial Park in Oak Ridge, Tenn.

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