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Comment by bryanlarsen | Hacker News Reader

Using expensive electricity for an energy intensive process seems like a good way to lose money.

Nuclear puts out a lot of heat. Retooling iron/steel foundries to use that heat directly (instead of converting it into electricity and back into heat) seems like the way to go.

Color me skeptical. Waste heat from a nuke plant is very low quality compared to the extremely high heat needing to make molten steel. We aren't taking about warming potato greenhouses here.

...low quality heat? Nuclear reactors produce nothing but heat. And it's all just heat, how you transfer it is very independent of the production process

https://en.m.wikipedia.org/wiki/Energy_quality

This is very wrong. Different processes require different temperatures. Iron and steel making requires very high temperatures. Heat from nuclear reactors cannot be used for this directly, as nuclear reactors do not get that hot, because they would melt. They are kept much cooler, usually at under 500 C.

Current reactor designs cannot get that hot without melting. I bet we could design a molten salt reactor that could safely get there, especially if electricity production is not a design goal.

I seriously doubt that. What would you make the reactor of, so that it withstands temperatures that melt steel? How are you going to move that coolant around? There are hard physical limits here. In reality, nobody would bother, because you can just make electricity and use it to melt steel instead.

Nuclear lightbulb engine - but for process heat!

https://en.m.wikipedia.org/wiki/Nuclear_lightbulb

Like it was not crazy dangerous enough. ;-)

I wonder how you’d transfer the heat without exposing the steep to radiation. I assume that would be bad anyways. I wish I paid attention more in physics, would love to know how such a system could be built.

A trivial heat exchanger does that, and every nuclear power plant already has one.

Today we avoid radiating electric generation equipment by running two steam loops through a heat exchanger; one that interacts with the hot reactor and a second that spins the generators. Perhaps you could do similar with molten salt loops? Might be tough finding a material that would work as an exchanger at the required temperatures though.

Just using electricity is probably cheaper and easier; large power plants are crazy efficient already.

Thorium-based reactors famously are constrained by the lack of such material which would withstand the contact with hot molten salt, especially somewhat radioactive.

As anyone with a boat knows, salt water is insanely corrosive and gets into everything. Even large container ships have to be regularly serviced.

I can only what hot molten salt does to industrial processes.

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