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Comment by joak | Hacker News Reader

The first sentence «Nearly all of our electricity is generated from heat powering a steam turbine» just explains why nuclear cannot scale: thermal power (including nuclear fission) needs huge amounts of water to cool down the turbine. The thermodynamic cycle needs a hot source and cold source. This is already a limitation, and France has to stop reactors in summer due to this problem.

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Yes, thermal power plants need a cold and hot end to operate, and they are designed to operate within the thermal "range" that its location can provide + some error. Now, this is not really a limitation, rather an engineering constraint. Thermal cycles can be stretched with multiple devices such a HRSG, in the case of combined cycles.

About powerplants in France shutting down because of cooling during the summer... I find it hard to believe this is a widespread issue, if an issue at all. Many of the existing nuclear reactors are reaching an age where massive maintenance schedules need to be executed. If the problem is extending the thermal range, that's relatively easy to fix.

Source: I used to build powerplants.

I think the issue is more not killing everything in the river the warmer water is released back into, so the temperature differential becomes unworkable at certain intake temperatures.

Was this due to reduced flows in the massive European drought?

I think also in hot summers - not an entirely new phenomenon and also something that happens with fossil fuel powerplants.

I agree with the intention. This has been part of the design constraints of a plant for at least 30 years... I reckon it is possible older plants didn't take steps to cool down the open water loop, but it is indeed relatively straight forward to tackle: cooling towers, open air reservoirs, and again heat exchangers...

It's not an easy thing to retrofit into an existing plant though: first of all France isn't the US and even though it's the biggest country in western Europe, it's relatively space constrained, especially in the places where plants are built, so most exiting sites are already quite cramped (even just post-Fukushima external diesel generators gave headache to my wife's colleagues in her plant site). Also in France we have a lot of reactors, on very few rivers (Rhône and Loire river have like a dozen reactor on each) so there's less margin than what we'd like.

My point is that thermal power doesn't scale well. If you need 10x more electricity (growing needs plus electrification of all energy) thermal pollution of rivers becomes a big issue.

This summer: «High river temperatures to limit French nuclear power production»

https://www.reuters.com/business/energy/high-river-temperatu...

Should we shut down all efforts to generate power that uses heat, steam, and turbines?

Yes. Even the steam turbine bit alone will make it unable to compete on price with renewables.

This is why fusion projects are looking for ways to directly generate electricity. If they run steam turbines they've lost before they even start.

Tongue in cheek, but wind turbines also need a hot and cold end in order to operate, the scale is just a little different.

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