This is not the first reactor to be cooled without water. The US built the Fast Flux Test Facility (FFTF) at Hanford beginning in the mid 70’s. It was cooled by liquid sodium and and tested to perform if the pumping system quit. It was shown the the liquid sodium provided enough creep through the system to maintain cooling until reactor shutdown.
Operation of the facility also produced medical isotopes to use to fight cancers and there was hope that that mission alone would justify continued operations beyond that a purely scientific reactor research project. Alas, the sky is falling anti nuke crowd won out and the Clinton administration shut the plant down.
IIRC, the USS Seawolf used electromagnetic pumps to move the liquid sodium. Very whizzy for late 1950’s technology...