Another is the small modular SVBR-100, which is essentially civilian version of submarine reactor that could be packed onto single rail car, and has no sodium nor fluoride involved.
The problem is that since 1995 or so there was never enough funding to go to production.
Japan and India also have them.
The problem seems to be that at least the Sodium type are more expensive to operate than traditional nuclear plants, so even though the technology has been around for a while, no countries are building very many of them.