https://www.twi-global.com/technical-knowledge/published-pap...
people use stainless steel, fiberglass, teflon and other common materials. The most notorious problem is that sCO2 dissolves in hydrocarbon oils, even very heavy hydrocarbons so keeping the CO2 from exiting through the turboshaft seals is challenging, but a solved problem.
The one obnoxious thing for nuclear use is that CO2 reacts with liquid sodium! It's not that hard to contain the effects of a CO2/sodium leak because the volume of the 1500 psi section is small, so that if the coolant loop bursts the overpressure in the (still not very big) confinement structure is more like 15 psi.
What do you mean by "economic competition"? Generally speaking with current technology there is no power cheaper than nuclear power. In that sense it is the most competitive power there is.
But not for private investment funds looking to own power generation and secure huge returns in relatively short term. They'd rather see more expensive inferior dirtier climate-changing power generation they can profit from, not government owned nuclear they can't ever compete with. And in that sense no project with long term investments in science, education, infrastructure will ever be competitive for capitalists. So does it really matter then?
Luckily not everyone is fond of capitalists. Ukraine, for example, recently decided to go against certain capitalist run countries pushing it to limit nuclear and finish building new reactors, because other power is not actually economically competitive. If Ukraine can, surely most of the world can do it too.
The real hazard of the current "renewable energy" economy that is when the sun doesn't shine the backup power is generated from methane (aka 'natural gas') which has very high power density and very low capital cost compared to the steam turbine either in a coal or nuclear plant. (If the airplane was propelled by a steam turbine, the turbine would be the size of the fuselage)
Almost no coal plants have been built in the period in which no nuclear plants have been built in the U.S. for pretty much the same reason. The steam turbine is so expensive it wouldn't be worth it even if the heat was free.
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If a new power source can beat fossil fuels in direct economics it saves the planet. The job is done.
With anything that involves forcing somebody to pay somebody else to make something that is allegedly sustainable the one thing you do know is somebody will get rich on the friction, if the earth is saved is beside the point.
If you love your children's grandchildren choose wisely.
Doesn't natural gas power plants also use turbines to generate electricity? How can it be cheaper than the steam turbine portion of a coal/nuclear power plant?
CCGTs are expensive. Simple gas turbines that are used to meet daily demand peaks are relatively cheap; as GP said they're basically stationary jet engines.
To me it's kind of bizarre that money is so cheap at present, but somehow it's still too costly to use it to invest in things with a delayed payback.
The glass factories, the microchip factories, infrastructure that runs aviation, etc. are a different business which cannot start and stop production around supply interruptions.
The good news (e.g. "gospel") is that U238 + n => Pu239 and that we've mined enough uranium that is sitting above ground (so called "waste") that we've got 200 years of carbon-free fuel to run our civilization.
It can't possibly be economically competitive if it is driving a steam turbine, a huge and precision-engineered power conversion device that dwarfs the reactor and often the heat exchangers. With higher temperature materials (liquid metal or salt coolant) and this kind of turbine
https://www.powermag.com/supercritical-co2-pilot-power-plant...
we would never lack for carbon free power.