Lithium Fluoride Thorium Reactor (LFTR). The founder is Kirk Sorensen who has been an evangelist for the LFTR design and Thorium fuel for years. Flibe is named after the molten salt coolant, a mixture of Lithium Fluoride and Beryllium Fluoride called Flibe (Fl Li Be). The Thorium fuel is mixed with the coolant and cycled through the reactor.
This reactor design includes a chemical treatment plant which Sorensen refers to as the “kidney” of the reactor. This removes byproducts and processes the Protactinium produced by neutron bombardment of Thorium into U233 fuel. This allows much more complete fuel usage than other designs and dramatically reduces waste products.
Despite being in business since 2011, their website doesn’t list a schedule for having a working reactor. The primary hurdle seems to be funding to further reduce the remaining technical challenges. They should benefit from the work currently being done at the Pacific Northwest National Laboratory (link).