From Antares' website, this appears to be a non-refuelable low power (100KWe -1MWe for 6+ years) reactor. The fuel design is not a new concept, pebble bead reactor designs have been for a while, and China appears to be working on one as well. The fuel design does have some advantages, such as online refueling, the ability to withstand the heat generated by the fission reaction without cooling, and in some designs the ability to disperse the fuel to shutdown the reactor. One challenge for earlier designs was the use of helium as a heat transfer medium which was hard to top from leaking past pump seals, etc. This design uses sodium/N2 loops, avoiding issues with helium. From their website, it appears they do not plan to scale it for utility use but focus on markets for small portable power that are not as cost sensitive, such as portable power for military use.