The Kemmerer Unit 1 project... would be used to demonstrate the TerraPower and General Electric-Hitachi Natrium sodium fast reactor technology. [0]
https://en.wikipedia.org/wiki/Sodium-cooled_fast_reactor
[0] https://www.nrc.gov/reactors/new-reactors/advanced/who-were-...
Nice, I like the sodium fast reactor concept. Produces less waste, can be passively cooled when shut down, and doesn't run pressurized so reactor vessel can be thinner.
Sodium leaks can be nasty, but they can be dealt with.