Sodium melts 98°C, a bit less than the boiling point of water. For comparison, pressurized water reactors use water in a temperature range between 275°C and 315

Sodium melts 98°C, a bit less than the boiling point of water. For comparison, pressurized water reactors use water in a temperature range between 275°C and 315°C. The higher the temperature, the higher the thermal efficiency of the electricity generator. Because the critical point of water is 374°C, no pressurized water reactor can get beyond this temperature, and in fact they all stay well below it. This limits the efficiency to about 33%. Sodium stays in liquid form all the way to 883°C. They will not run the reactor that hot, for various reasons, but they can run it at more than 500°C. Still, well below lava levels. [1] https://en.wikipedia.org/wiki/Sodium-cooled_fast_reactor#Advantages https://en.wikipedia.org/wiki/Sodium-cooled_fast_reactor#Adv...