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Comment by chasil | Hacker News Reader

Materials science is a great expense.

- Monocrystaline turbine blades have become required due to their ability to operate at higher temperatures than the melting points of the metals that compose their alloys. The requirement is their efficiency in power production. These are also used in aerospace, but are complex and difficult to produce.

- Common water reactors must contain insanely high pressures, enough to force water to remain liquid at 300°C or higher. This is not inexpensive.

- Molten salt reactors, where deployed, must be composed of alloys resistant to molten (negative) chloride ions and (positive) sodium ions, assuming the fluid chemically disassociates. Alloys that can withstand these conditions are also not inexpensive.

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It’s definitely an expense. But this doesn’t fully explain why nuclear is expensive.

-Current nuclear reactors aren’t nearly hot enough to need single crystal turbine blisks. We’re talking on the order of 300°C.

-Coal power plant routinely hit much higher temperatures in supercritical and ultra-supercritical (yes, that’s a real term) steam generators. We don’t have quite as bad a problem building coal power plants.

-We’re not currently building molten salt reactors for power generation.

You didn’t say anything that was wrong. I’m just don’t think this is the reason building reactors is so expensive.

Yeah, the high tech blades occur in combustion turbines.

A simple cycle combustion turbine power plant might have 5% of the capital cost per watt of a nuclear power plant.

Monocrystalline turbine blades reduce creep, they don't allow the blade to remain solid if its above the melting point.

But... isn't the melting point of the alloy far above the melting point of the constituent pure metals?

I'd ask my metalurgist friend, but I don't want to look like an idiot.

In a common example, the alloy of iron and carbon known as cast iron melts at a lower temperature than pure iron or pure carbon (or low-carbon steel).

But there are other cases where an alloy has higher melting point. Ti(88)Al(12), for example.

Film cooling and coatings are what allow operating temperatures above the melting temperature. That doesn’t mean the metal is above its melting temperature.

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