[bewaretheirs]

According to their web site at https://kairospower.com/technology/ it uses a molten fluoride salt based coolant but unlike the MSR/LFTR designs the fissionable fuel is not dissolved into the coolant; instead, the Kairos reactor design puts the fissionables in pellets that are intended to remain solid while in operation; it looks more like a pebble-bed reactor than a MSR/LFTR.

[credit_guy]

Yes, you are right, I was wrong. The Hermes design is even more conservative than the MSRE design. It is basically the same design as the helium-cooled reactor HTR-PM that China started operating two years ago, only that the helium cooling is replaced with FLiBe cooling; this achieves a higher power density plus a higher rate of passive cooling in case anything goes wrong.

This IAEA report [1] has more details about this design, and the dozens if not hundreds of other types of molten salt reactor designs. The relevant section for the Kairos Hermes design is 4.5 (pages 41-44).

[1] https://www-pub.iaea.org/MTCD/Publications/PDF/STI-DOC-010-4...