General > General Technical Chat

Germany shutting down last nuclear power plants on April 15th

<< < (12/56) > >>

Siwastaja:

--- Quote from: Kleinstein on April 10, 2023, 06:29:13 pm ---Building new nuclear power plants makes relatively limited sense.

--- End quote ---

This. It's worth noting the Finnish Olkiluoto 3, which now seems kinda-sorta operational (!!!), after being 12 years late, is now the most expensive building in the whole human history; a total political disaster.

Extending the permits for old plants also comes with risks; you can't do it indefinitely.

However, Germany has had to make the choice between fossils and nuclear during the transition time to more sustainable energy policy (with the final target of using neither). The correct answer is to use sensible mix of both, on case-by-case basis. What Germany has done is use the most politically unstable forms of fossil fuels (specifically Putin's fart, which also did not come for free but required actual investments in the pipeline, there is no free lunch), and accelerate the transition away from nuclear as fast as possible. This is not sensible; it's politics driven by something else than factual analysis of what would be best for the country (and EU as a whole, too) in the long run.

The advantage of fossil fuel is, the downsides average out. Their CO2, SO2, particulates etc. average; the less you use them, the smaller the problem. Therefore supplementing uncertain renewable production with fossil fuels is not a huge problem. Political risk more than averages out; halve the use of fossil fuels, and the risk is practically totally gone as you can choose where to buy from.

But by closing the NPPs at higher-than-natural rate, Germany has had to keep the fossil fuel use relatively constant; advances in renewables have been directly removed from nuclear, not 50:50 from nuclear + fossils.

daqq:

--- Quote from: Siwastaja on April 11, 2023, 07:17:57 am ---
--- Quote from: Kleinstein on April 10, 2023, 06:29:13 pm ---Building new nuclear power plants makes relatively limited sense.

--- End quote ---

This. It's worth noting the Finnish Olkiluoto 3, which now seems kinda-sorta operational (!!!), after being 12 years late, is now the most expensive building in the whole human history; a total political disaster.

--- End quote ---
The key word being political - the incompetence of administrations is an argument against politicians, imbecilic project management and copious amounts of bureaucracy rather than nuclear as a concept. In Slovakia we too had some major delays, but again, that speaks of politics and state project management rather than nuclear.

Basically what I'm seeing here is an attitude of giving up on big projects the sort of that were done in the past with enthusiasm and looking forward. Instead we are creating overpriced pathetic workarounds and small not-fixes that can have a label with whatever virtues that the current administration wish to signal slapped on to them. Meanwhile in the background solutions (whether it's infrastructure or heavy industry) from 30-50 years ago are working overtime to compensate for the lack of will to build something new and worthwhile.

If we want to adopt an attitude where we just give up big, ambitious projects as a whole, let's just say it right here and now. And we may as well throw in the towel.

Xena E:
 ^^^ :clap: :clap: :clap: :clap: :clap: :-+ :popcorn:^^^

rf-messkopf:
To keep this at a technical level (after all, this is an engineering forum, not a political one):


--- Quote from: Someone on April 11, 2023, 01:24:49 am ---Nuclear reactors are finicky/metastable

--- End quote ---

Huh? Commercial reactors are designed to be undermoderated, i.e., an increase in fuel temperature or a reduction in moderator density leads to a power reduction. For this reason, in a PWR, slight variations in power demand up to a few percent do not require any input from power control elements. In fact, I can assure you from first hand experience that you can safely turn off all closed loop reactor power control (actually three control loops in series in a German PWR in normal at-power operation), and it will just sit there without moving (stable equilibrium). BWRs have a bit more complicated unit capacity control systems, because reactor pressure and steam voiding have a pronounced effect on reactivity, so they use a control concept in which the set generator power in part acts directly on the power control elements (recirculation pumps and control rods in a BWR). But still, they are undermoderated by design.


--- Quote from: james_s on April 11, 2023, 01:14:00 am ---Something I have always wondered about but not looked into is since the spent fuel is still active enough that it has to be kept cool, clearly there is still potential energy there so why can't it be put to use?

--- End quote ---

After a four or five years when the spent fuel assemblies are transferred to dry storage, this is just a couple of kilowatts, i.e., not worthwhile. For example, this storage cask is rated for a maximum of 39 kW total heat load.

Someone:

--- Quote from: rf-messkopf on April 11, 2023, 10:09:59 am ---
--- Quote from: Someone on April 11, 2023, 01:24:49 am ---Nuclear reactors are finicky/metastable
--- End quote ---
Huh? Commercial reactors are designed to be undermoderated, i.e., an increase in fuel temperature or a reduction in moderator density leads to a power reduction. For this reason, in a PWR, slight variations in power demand up to a few percent do not require any input from power control elements. In fact, I can assure you from first hand experience that you can safely turn off all closed loop reactor power control (actually three control loops in series in a German PWR in normal at-power operation), and it will just sit there without moving (stable equilibrium).
--- End quote ---
Sounds like an example of short term stability, not a truly stable system hence the careful choice of metastability as a description. Leaving an inherently safe/stable reactor to its own devices usually means a rapid and steady drop in reactivity (for legitimate and well thought out safety reasons) rather than continued stable operation. They are intentionally not stable, and partly because of the fuel becoming unable to sustain fission (despite having not yet used much of the available energy).

Requiring graded/designed loadings of differing fuel elements across the core to be functional is the sort of thing that makes the system finicky. It is not just a case of pouring more fuel in as it gets used up, almost everything about the nuclear fuel cycle needs really carefully designed processes to maintain operation.

You've gone off and talked around the original question like a true politician/industry spokesperson:

--- Quote from: rf-messkopf on April 11, 2023, 10:09:59 am ---
--- Quote from: james_s on April 11, 2023, 01:14:00 am ---Something I have always wondered about but not looked into is since the spent fuel is still active enough that it has to be kept cool, clearly there is still potential energy there so why can't it be put to use?
--- End quote ---
After a four or five years when the spent fuel assemblies are transferred to dry storage, this is just a couple of kilowatts, i.e., not worthwhile. For example, this storage cask is rated for a maximum of 39 kW total heat load.
--- End quote ---
Someone asks about energy, so subtly direct the discussion to power....

--- Quote from: Someone on April 11, 2023, 01:24:49 am ---
--- Quote from: james_s on April 11, 2023, 01:14:00 am ---Something I have always wondered about but not looked into is since the spent fuel is still active enough that it has to be kept cool, clearly there is still potential energy there so why can't it be put to use?
--- End quote ---
Nuclear reactors are finicky/metastable and only use a small percentage of the "available" energy in the fuel. It gets into the specifics of the particular fuel cycles
--- End quote ---
The answer is complex and multifaceted, but it is true that very very little of the available nuclear energy is used in current fuel cycles.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod