I believe that the Seawolf (SSN 575) was a US Nuclear Submarine with a liquid sodium core.
Problems, problems, problems.
Something about keeping it liquid all the time, interaction with water, bad zoomies, etc.
They replaced the sodium core with a regular naval nuclear core and the sub had an illustrious career doing the Blind Man’s Bluff thing.
Yes.
I can confirm and cannot deny that I worked on the Seawolf nuclear plant (the new one) during those Blind Man's Bluff years at Mare Island - which I can neither confirm or deny actually happened. 8<)