Arglebargle III posted:

Fun fact, the Russian Lyra-class subs, known to NATO as the Alfa-class, used a compact and powerful liquid-metal reactor design known as a lead-bismuth reactor. Liquid metal is a fantastic heat transfer medium, and it has the nifty safety feature that if it ever gets out of the reactor it solidifies.

Unfortunately it also means that you can literally never turn it off, because it will freeze and turn into a solid block of lead until you can get your dumb ass towed back to base and restart the reactor with an umbilical. Well, some other captain will restart the reactor, because you just got shitcanned.