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Comment by harrouet | Hacker News Reader

I always get touchy when someone compares the cost of nuclear MWh to the ones of solar and wind turbines, because they are essentially NOT the same MWh.

Nuclear works 24x7 on its own. Intermittent energies don't.

Intermittent energies need a whole infrastructure on their side (usually gas / coal power plants) to guarantee 24x7 electricity. This cost should be factored in.

If you are not convinced, think about your cell phone service: would you pay the same for a network that works only when it is sunny ? No. Not the same.

NB: don't even mention batteries, when the largest scale projects, very expensive, can only supply power for a few minutes at grid scale.

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Nuclear is also intermittent - ask Europeans.

During January this year, nuclear contributed about 62TWh of the electricity generated in the EU while in June this had fallen to 43.7TWh - about a 30% decrease. The deficit was largely filled by a surge of solar generation as well as burning more gas.

The drop was due to both scheduled and unscheduled downtime. There is no such thing as a non-intermittent source - even without unscheduled outages, a typical nuclear plant spends over 4 weeks offline a year. You need to be able to handle that also - i.e. with redundancy and backup.

Also because nuclear (like coal - the other thermal steam generation tech) requires huge scale to be profitable, it requires huge transmission investment. Contrast this with solar, for example, which is economic to scale down and can deployed in a more distributed pattern.

First, overall consumption is smaller in June than in January, when days are shorter and heating is on. So I don't see how comparing these 2 numbers makes a relevant argument.

Second, you can't compare technical (planned) maintenance with the uncontrolled intermittence of wind or solar. Not having sun or wind during peak demand is the actual problem. In Europe, peak demand is 6-8pm in winter: no sun, no wind.

The last problematic preventive maintenance, mandated by the supervising agency, which forced France to import MWh for a few months was in 2022. Anything human-made can have a downtime. It was actually a voluntary (although mandated) downtime in this case.

Moreover, you may not know that nuclear is forced to reduce output when intermittent energies increase their output. There is no good technical reason for this, it is just how the regulation has been made (you can imagine lobbying entities asking for it). You may have noticed more sun in June than in January, so yes nuclear may have had to reduce output. Not due to the technology.

Yes consumption varies by month but that's not why nuclear output fell by 30%.

There was wide scale unscheduled reduction in nuclear generation this Summer: in Hungary (Paks - reduced to 10% output), Romania (full shutdown of Cernavodă), France (5 plants fully shutdown, 2 curtailed) and Switzerland (Beznau operating at 50% then shutdown). All due to weather (lack of water for cooling).

I clearly distinguished scheduled from unscheduled downtime and am talking purely about nuclear intermittency caused by unscheduled downtime. And even if I didn't/wasn't, your original claim:

> Nuclear works 24x7 on its own.

simply does not stand up to any scrutiny.

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