This is just wrong. Nuclear is perfectly fine for nighttime because nighttime is highly predictable and doesn't fluctuate very much.

My state (NSW, Australia) for example uses no less then 6 GW at all times of day. Variable load is on top of that during the day.

If we had 6GW of nuclear plants, our grid would be almost completely green and they'd run at 100% utilization.

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ViewTrick1002 2 days ago | parent [-]

Now calculate what it costs running a nuclear plant only at night.

You’ll end up at $400 per MWh excluding transmissions costs, taxes etc.

Your state already has coal plants forced to become peakers or be decommissioned because no one wants their expensive electricity during the daytime. Let alone a horrifyingly expensive new built nuclear plant.

https://www.abc.net.au/news/2024-10-13/australian-coal-plant...

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XorNot a day ago | parent [-]

Not what I was responding to. Saying nuclear plants can't ramp for predictable night time demand is wrong.

Nuclear plants can't do instant demand response, but they can absolutely respond over windows of several hours.

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ViewTrick1002 a day ago | parent [-]

But not economically. And it can’t ramp twice. Once is easy.

For the French to do load following they sync their entire fleet to manage it. Letting plants take turns and spread out where they are in their fuel cycle.

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leonidasrup a day ago | parent [-]

Nuclear power plants can and do load follow.

According to the current version of the European Utility Requirements (EUR) the NPP must be capable of a minimum daily load cycling operation between 50% and 100% Pr, with a rate of change of electric output of 3-5% Pr /minute.

https://www.oecd-nea.org/nea-news/2011/29-2/nea-news-29-2-lo...

The problem with integration of solar and wind with nuclear power is that it doesn't make economical sense to build solar and wind in electric grid based on nuclear power generation. Because the fuel costs of nuclear power plants are so low and the capacity factors can be very high (nuclear power plants need only very short pauses for maintenance) building solar and wind in such electric grid doesn't lower the costs for grid customers.

This is big problem for solar and wind investors and manufacturers.

Nuclear power is a big competition also for coal and gas producers. I think coal producers in Australia are quite scary even of the idea for nuclear power production in Australia.

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ViewTrick1002 a day ago | parent [-]

Meanwhile to achieve load following in France they sync the fuel cycles of the entire fleet and then let the plants take turns across the week.

You have it the other way around. The marginal price for renewables are zero so consumers buy that first. Which means nuclear power, like the coal plant I linked, is forced to load follow. Which craters their earning potential.

Nuclear power is literally the worst combination imaginable for a grid with any amount of renewable penetration. They both compete for the same slice, the cheapest most inflexible, a competition which nucler power loses handily.

Which means, the window of opportunity for new built nuclear power is gone.

> Our analysis finds that even if, reversing the historical trend, overnight construction costs of nuclear half to 4,000 US-$2018 per kW and construction times remain below ten years, the cost-efficient share of nuclear power in European electricity generation is only around 10%. Nuclear plants must operate inflexibly and at capacity factors close to 90% to recover their investment costs, implying that operational flexibility – even if technically possible – is not economically viable.

https://www.sciencedirect.com/science/article/pii/S2211467X2...

This is a future you can't escape from. Flexibility is mandatory. It is coming from pure incentives. Lets explore them:

Why should a household or company with solar and storage buy expensive grid based nuclear power when their own installation delivers? They don't.

Why should this household's or company's neighbors buy expensive grid based nuclear powered electricity rather than the zero marginal cost surplus renewables? They don't.

EDF is already crying about renewables cratering the earning potential and increasing maintenance costs for the existing french nuclear fleet. Let alone the horrifyingly expensive new builds.

And that is France which has been actively shielding its inflexible aging nuclear fleet from renewable competition, and it still leaks in on pure economics.

https://www.bloomberg.com/news/articles/2026-02-16/edf-warns...

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leonidasrup a day ago | parent | next [-]

If you are now (in the year 2026) optimizing only for costs of producing electricity then you end with electric grid which has more or less structure of Chinese electric grid - big chunk produced with domestic fueled base-load fossil fuel power plants+nuclear power plants, as much hydro as you can build, little bit variable renewables.

If for example Germany would optimize for costs of producing electricity then they would not shut down already build and running nuclear power plants, would not import LNG, would use much more domestic coal.

If you care for CO2 emissions (which is not the case in China) then the problem of electric grid is much more complicated.

Germany is a nice example of electric grid with significant amount of variable renewable penetration (lot of solar and wind, small amount of hydropower). First they decided to phase-out nuclear power and ban construction of nuclear power plants (beginning in 2000), then they decided to replace domestic coal production with imported fossil fuels and then decide to decarbonize grid (until 2045), which is now much more expensive because nuclear phase-out.

In contrast France has already decarbonized the electric grid.

The economic situation EDF is bad because decade long taxation of EDF, the ARENH mechanism.

Under the so-called Regulated Access to Incumbent Nuclear Electricity (Accès Régulé à l’Electricité Nucléaire Historique, ARENH) mechanism set up to foster competition, rival energy suppliers could buy electricity produced by EDF's nuclear power plants located in France that were commissioned before 8 December 2010. Under such contracts, between July 2011 and December 2025, suppliers could buy up to 100 TWh - or about 25% of EDF's annual nuclear output - at a fixed price of EUR42 per MWh.

https://www.world-nuclear-news.org/Articles/Agreement-on-pos...

https://www.8advisory.com/en/2026/03/31/nuclear-power-naviga...

So no France didn't actively shielding its inflexible aging nuclear fleet from renewable competition, it was shielding renewable competition from its aging nuclear fleet.

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swiftcoder a day ago | parent | next [-]

> Chinese electric grid - big chunk produced with domestic fueled base-load fossil fuel power plants+nuclear power plants, as much hydro as you can build, little bit variable renewables

This is not an accurate representation of China's power generation mix. Yes, they are only about 40% total renewables thus far, but less than 5% of that is nuclear.

Their hydro contribution is double that of nuclear, and both wind and solar are drastically higher still.

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ViewTrick1002 a day ago | parent | prev [-]

I love the framing. "Little bit of renewables" when in China they are literally 5x in size of the nuclear production. Nuclear power in China peaked at 4.7% in 2021 and is now down to 4.3%. Entirely irrelevant.

The problem I am mentioning has nothing to do with ARENH, and the protectionism isn't the ARENH. It is not building more renewables and dragging their feet on interconnects.

	▲	leonidasrup a day ago \| parent [-]
		Electricity in People's Republic of China in 2025 58% fossil fuels 14% hydropower 11% solar 11% wind 4.6% nuclear https://lowcarbonpower.org/region/People%27s_Republic_of_Chi... For France, it doesn't make economic sense to build more wind and solar and build more interconnects. It will be interesting to see how wind and solar will evolve in Germany after changes in EEG subsidies. https://www.cleanenergywire.org/news/german-econ-min-conside... https://montel.energy/resources/blog/future-of-german-eeg-su... https://www.taylorwessing.com/en/insights-and-events/insight...

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leonidasrup a day ago | parent | prev [-]

All the new EPR builds went terribly bad, long over planned time, over budget.

Some argue thats because European Pressurised Reactor is design that merges German Konvoi reactors with French Framatome N4 design. A design that is trying to please both German and French regulators.

https://www.decouple.media/p/epr-the-reactor-that-tried-to-p...

https://www.decouple.media/p/state-of-the-atom-2025