General > General Technical Chat
Germany shutting down last nuclear power plants on April 15th
Kleinstein:
--- Quote from: Ed.Kloonk on April 22, 2023, 05:53:36 am ---
--- Quote from: Siwastaja on April 22, 2023, 05:45:13 am ---Nuclear needs fossil backup (nearly) as much as renewables do. Always been this way.
--- End quote ---
Why? What do you mean? Do they not provide continuous output?
--- End quote ---
They normally provide continuous output, but that is exactly part of the problem: they don't provide reseves for peak power and possibly too much at night.
The other point is that there is a chance that they have to shut down for safety reasons - not very likely, but it can happen, especially with many reactors of the same type and thus a possibly common weak point in the design. There have been times when multiple reactors had to shut down for urgent unplaned safty checks. A fault in one plant can thus trigger the shut down for a whole series of reactors of the same type.
Not having that option to shut down if a flaw is found is a very bad idea and would compomise safety.
With nuclear the backup is normally not needed that regular, but one still needs a plan B.
Siwastaja:
--- Quote from: Ed.Kloonk on April 22, 2023, 05:53:36 am ---
--- Quote from: Siwastaja on April 22, 2023, 05:45:13 am ---Nuclear needs fossil backup (nearly) as much as renewables do. Always been this way.
--- End quote ---
Why? What do you mean? Do they not provide continuous output?
--- End quote ---
No, they don't. Sudden unplanned SCRAM events have to be accounted for (not a massive problem in a county with dozens of reactors and good grid, though), but even more importantly, nuclear is almost always dimensioned to run at 100% power continuously while load variations are large. This is the reason why we never saw >50% nuclear in any country, but always as a mix with fossil fuels; the synergy with fossils is good as their production can be ramped up or down quickly.
Solar and wind production is similar "special snowflake", which just replaced nuclear production in Germany, and still needs supporting fossil fuels.
The big difference is, solar and wind production is so much cheaper per produced kWh to build and maintain (total cost of ownership with all true expenses) that overdimensioning them does not become such a problem overdimensioning nuclear production would have been (no one tried).
nctnico:
--- Quote from: Siwastaja on April 22, 2023, 07:14:05 am ---
--- Quote from: Ed.Kloonk on April 22, 2023, 05:53:36 am ---
--- Quote from: Siwastaja on April 22, 2023, 05:45:13 am ---Nuclear needs fossil backup (nearly) as much as renewables do. Always been this way.
--- End quote ---
Why? What do you mean? Do they not provide continuous output?
--- End quote ---
No, they don't. Sudden unplanned SCRAM events have to be accounted for (not a massive problem in a county with dozens of reactors and good grid, though), but even more importantly, nuclear is almost always dimensioned to run at 100% power continuously while load variations are large.
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That depends entirely on the type of reactors. The ones that are planned in the NL are types that can be regulated quickly. But even without that, you can convert the excess electricity into hydrogen. Keep in mind new nuclear power plants aren't build in a few years so by the time these new plants are finished, the hydrogen infrastructure and demand will be scaled up much further.
iMo:
What about those Small Modular Reactors?
https://en.wikipedia.org/wiki/Small_modular_reactor
Siwastaja:
--- Quote from: nctnico on April 22, 2023, 08:25:08 am ---The ones that are planned in the NL are types that can be regulated quickly
--- End quote ---
It's not about being technically able to do it, just about cost. If you build too much and throttle them to significantly <100% average power, TCO will be even higher than it already is. Given the always-existing fluctuations in load demand, and increased fluctuations in renewable production, the maximum cost-effective share of nuclear will only get lower and lower.
--- Quote from: iMo on April 22, 2023, 08:32:43 am ---What about those Small Modular Reactors?
https://en.wikipedia.org/wiki/Small_modular_reactor
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Was following with interest a decade ago. Except total 2 demonstration units (in China and Russia), it did not happen, no signs of happening in any meaningful scale. Like Solar Roadways, one needs to understand the difference between ideas/marketing and practical solutions. In the end, the market makes the choice. This is one of those "by all means prove me wrong" cases.
The whole idea is based on mass manufacturing bringing costs down: classically, smaller units are higher cost per energy produced, so you need to compensate somehow, and that "somehow" is supposed to be making thousands. But it's a chicken-egg problem, as the market won't buy the expensive reactors, mass manufacturing and getting the costs down will never happen.
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